JPH03277556A - Ink jet recording device - Google Patents

Abstract

PURPOSE:To eliminate wasteful ink consumption and ensure rapid ink supply by providing an ink pressure feed device which sends ink under pressure and a bypass route between a tank which stores ink to be fed to a recording head and the recording head. CONSTITUTION:An ink supply to a recording head unit 1 is performed by a pump 24 which is an ink pressure feed means provided in the route of a feed pipe 11 communicating with a tank 13. In addition, a bypass route which allows the feed pipe 11 to communicate with a return pipe 12 with passing through a liquid chamber 30 is provided. This bypass route is opened or closed by valves 403, 404 and during a routine recovery operation, a small quantity of ink is discharged from a discharge orifice 31 and thus the interior of the discharge orifice 31 and a head surface (not illustrated in the figure) are cleaned. Further, when the interior of a feed path communicates with an atmosphere due to the replacement of a recording head, the ink can be bypassed by opening the valves 401, 402 and closing valves 403, 404. Consequently, the ink consumption is reduced by limiting the ink ejection from the discharge orifice 31 to a minimum allowable extent.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an inkjet recording device.

(Prior Art) Inkjet recording devices that perform recording by ejecting ink onto a recording material have been known.Since this inkjet recording device is a non-impact type recording device, it produces less noise and has many advantages. It has the advantage of being easy to record color images by using colored ink, and has become rapidly popular in recent years.However, inkjet recording devices eject ink directly from fine nozzles in the recording head. In order to keep the ink in a state where it can be ejected at all times, special considerations not seen in other recording methods are required.

For example, if air enters the ink supply path from the ink tank to the recording head and new ink needs to be filled, the circulation recovery operation using normal pressurized circulation or recovery means such as suction It is configured to be carried out using

[Problem to be solved by the invention]

In the above-described conventional inkjet recording apparatus, when it is necessary to newly fill ink into the ink supply path, this is done using recovery means such as normal pressurized circulation or suction. When performing difficult work, a large amount of ink is discharged from the nozzle (discharge port), which is wasted and is time consuming. Particularly, in an inkjet printing apparatus that uses a multi-nozzle printing head, ink is ejected from each nozzle, which poses a big problem.

The present invention has been made in view of the drawbacks of the above-mentioned prior art, and an object of the present invention is to provide an inkjet recording device that can quickly fill an ink supply path with ink without wasting ink. shall be.

[Means to solve the problem]

The inkjet recording device of the present invention includes: a recording head that ejects and flies ink droplets from an ejection port; a tank that stores ink to be supplied to the recording head; and an ink that is provided between the recording head and the tank and that is stored in the tank. In an inkjet recording apparatus comprising a circulation path for circulating and supplying ink to a recording head, and an ink pressure feeding means provided in the circulation path for feeding and circulating ink under pressure, the circulation between the pressure feeding means and the recording head is provided. A bypass path is provided for bypassing the recording head.

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

[Effect]

Since the bypass path is provided, ink flows into the bypass path and the recording head depending on the ratio of the resistances of these lines. Therefore, the amount of ink supplied to the print head decreases, and the amount of ink discharged from the ejection ports also decreases. If a valve is provided in the connection between the circulation path and the print head or in the bypass path, the amount of ink supplied to the print head is further reduced by the valve, and the amount of ink discharged from the ejection ports is also further reduced.

(Example) Examples of the present invention will be described below in detail and specifically based on the drawings.

FIG. 1 is a perspective view showing the appearance of an embodiment of an inkjet recording apparatus according to the present invention, FIG. 2 is a perspective view showing the configuration of the recording head 1 in FIG. 1, and FIG. FIG. 3 is a diagram showing the configuration of a supply recovery system.

This embodiment is a case of a multicolor recording apparatus, where 1 is a plurality of recording heads IA to I configured as shown in FIG.
There is a recording head unit consisting of recording heads IA to ID, and recording liquids of different colors are ejected from the respective recording heads IA to ID. In addition, an electrothermal transducer 32 shown in FIG. 3 is provided along the liquid path of each of the recording heads IA to ID to which an applied voltage is supplied in order to generate thermal energy for ejecting the recording liquid. . 2A to 2D are each recording head 'I
Temperature detection means, such as temperature sensors such as a thermistor, thermocouple, or varistor, are attached to A to ID, respectively, and 20A to 20D are heaters attached to each of them. The temperatures detected by these temperature detection means 2A to 2D are supplied to a temperature control device as described later, and the heaters 20A to 20 are controlled to maintain a predetermined set temperature.
ON/OFF of D is controlled.

In FIG. 1, 3 is a carriage on which the recording head unit 1 is mounted and moves along a guide rail 4, 5 is a timing heald for moving the carriage 3, and 6 is 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 that cooperate with the roller 9. The sheet is fed in the direction. Reference numeral 11 in FIGS. 2 and 3 denotes a supply pipe 1 that supplies ink to the recording heads IA to ID, respectively.
2 is the recording spatula I” I Ink from A~ID to tank 1
3 (see FIG. 3), and 14 in FIGS. 1 and 3 faces the recording head unit 1 when the carriage 3 is guided to the home position H, and is used to circulate the ink under pressure. This is a non-discharge recovery device for multiple recording heads that operate.

Next, with reference to FIG. 3, the bypass route of the supply recovery system, which is the main point of the present invention, will be explained.

Ink is supplied to the recording head unit 1 by a pump 24, which is ink pressure feeding means, provided in the path of the supply pipe 11 communicating with the tank 13. Supply pipe 1
The ink injected into the liquid chamber 30 inside the recording head unit 1 through the liquid chamber 1 is returned into the tank 13 through the liquid chamber 30 and the return pipe 12 . A valve 401 is provided at the connection between the liquid chamber 30 and the return pipe 12, and a valve 402 is provided at the connection between the liquid chamber 30 and the supply pipe 11. In addition, the liquid chamber 30
A bypass path is provided to communicate the supply pipe 11 and the return pipe 12 without intervening, and the bypass path is opened and shut off by valves 403 and 404 provided near the entrance and exit portion of the bypass path.

During normal recovery operation, the recording head 1 is in pressure contact with the non-ejection recovery device 14, the two valves 403 and 404 are in the closed state, and the two valves 40. , 402 are open, so the ink is circulated by the pump 24 in the direction of the arrow. At this time, a small amount of ink is discharged from the ejection port 31, thereby cleaning the inside of the ejection port 31 and the head surface (not shown).

Next, a case will be described in which the inside of the supply system is communicated with the atmosphere due to replacement of the recording head or the like and must be filled with ink. In this case, when the ink is pumped through the supply system described above and continues to be filled, the ink passes from the tank 13 through the supply pipe 11, fills the liquid chamber 30 and the discharge port 31, and then enters the return pipe 12, where the ink enters the return pipe 12. Return to tank 13. Here, since the pump 24 performs pressure feeding until the ink returns to the ink tank from the return pipe 12 after filling the liquid chamber 30 and the discharge port 31, the ink continues to be discharged from the discharge port 31. There, the ink passes through the valve 402 and fills the liquid chamber 30 and the discharge port 31, and the ink passes through the valve 40. When the ink is reached, the valves 40□ and 402 are closed and the valves 403 and 404 are opened to bypass the ink and fill the ink supply system with ink without causing the ink to be discharged from the ejection port 31 more than necessary. I can do it.

Actual 400dpi, 256-nozzle bubble jet recording head, thread path from ink tank to liquid chamber 300+n
m, pipe diameter φ2ff1, water head difference of 50 mm between the lowest discharge port 31A and the liquid level in the ink tank, and a gear pump with a liquid volume of 10 cc/sec as the ink pressure feeding means, the ink is circulated for 1 second as shown in the arrow. The ink began to flow out from the ink tank 13 in the direction shown in FIG. Next, the valves 400 and 402 were closed, the valves 403 and 404 were opened, and one more circulation was performed, thereby completing the filling of the ink in the path of the return pipe 12. At this time, the amount of ink discharged by one ink pressurization is approximately 1 cc, so approximately 1 cc of ink was saved.

The opening/closing operations of each valve and the pumping operation of 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, and the control operation of this embodiment will be explained below with reference to FIG.

When the device user inputs an instruction to perform circulation recovery and the number of times, the control device receives the input (step 5101) and determines that the number of times circulation recovery is to be performed is 2 or more times (n times). (Step 510)
2). 2 if the circulation recovery operation only needs to be performed once.
valves40. .

402 is in the "open" state, and the two valves 403 and 40° are in the "open" state.
The entire supply path circulation operation is performed once to bring the entire supply path into the "closed" state (step 5105), and when the circulation recovery operation is performed n times, in addition to performing the above-mentioned entire supply path circulation operation once, the two valves 40 are ., 402 are in the "closed" state, and the two valves 403
, 404 are in the "open" state (n-1) times (step 5103, step 51).
04). After this, the operation ends. The above methods have saved me a lot of ink consumption. Furthermore, since the pressure applied to the ejection ports was reduced, the life of the J recording head was extended.

Note that in the embodiments described above, the ink flow path was changed by providing two valves each in the bypass section and the connection section with the liquid chamber, but the number of these valves differs from this. There is no limitation, and it may be increased or decreased depending on 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, some ink is discharged from the ejection port, but in reality, much of the ink flows to the bypass portion where the resistance of the pipe is low. Alternatively, the bypass section may be provided with only one or two valves so that it can be used like a normal recording head, or the connection section with the liquid chamber may be provided with only one or two valves. may be provided.

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

In this embodiment, a pump 25 is also provided in the return pipe 12 to pump ink to the liquid chamber 30. Since the other configurations are similar to those shown in FIG. 3, the same reference numerals are given and explanations are omitted.

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

In this embodiment, ink can be supplied to the liquid chamber 30 from both the supply pipe 11 and the return pipe 12, so this can be done more quickly than the entire supply channel circulation operation shown in the first embodiment. I was able to do it.

The present invention provides excellent effects particularly in bubble jet recording heads and recording apparatuses among ink jet recording systems.

As for typical configurations and principles thereof, it is preferable to use the basic principles disclosed in, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740,796. Is this method applicable to both the so-called on-demand type and continuous type? In particular, in the case of the on-demand type, the arrangement corresponds to the sheet holding the liquid (ink) and the liquid path. By applying at least one drive signal that corresponds to recorded information and causes a rapid temperature rise exceeding nucleate boiling to the electrothermal transducer, the electrothermal transducer generates thermal energy, and the recording head This is effective because it causes film boiling on the heat-active surface of the ink, resulting in the formation of bubbles in the liquid (ink) in one-to-one correspondence with this drive signal. The growth and contraction of the bubble causes liquid (ink) to be ejected through the ejection opening to form at least one drop. When this drive signal is in the form of a pulse, the growth and contraction of the bubbles is carried out immediately and appropriately, so that ejection of liquid (ink) with particularly excellent responsiveness can be achieved, which is more preferable. As this pulse-shaped drive signal, those described in US Pat. No. 4,463,359 and US Pat. No. 4,345,262 are suitable. Incidentally, U.S. Patent No. 43 of the invention regarding the temperature increase rate of the heat acting surface
If the conditions described in the specification of No. 13124 are adopted, even more excellent recording can be performed.

The configuration of the recording head includes, in addition to the combined configuration of ejection ports, liquid paths, and electrothermal converters (straight liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned specifications, a heat acting section. US Pat. No. 4,558,333 and US Pat. No. 4,459,600 disclose a configuration in which the
It may also be configured using the specification. In addition, JP-A No. 123 of 1982 discloses a configuration in which a common slit is used as a discharge part of a plurality of electrothermal converters.
No. 670 and Japanese Unexamined Patent Publication No. 138 of 1982, which discloses a structure in which a discharge portion is provided with an opening that absorbs pressure waves of thermal energy.
The present invention is also effective with a configuration based on the No. 461 publication.

Furthermore, 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 increased by combining multiple recording heads as disclosed in the above-mentioned specification. The present invention can more effectively exhibit the above-mentioned effects, regardless of whether the configuration satisfies the above requirements or the configuration is configured as a single recording head formed integrally.

In addition, a replaceable chip-type recording head that is attached to the device body enables electrical connection to the device body and ink supply from the device body, or a chip-type recording head that is installed 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, preliminary auxiliary means, etc. for the recording head, which are provided as a configuration of the recording apparatus of the present invention, because the effects of the present invention can be further stabilized. Specifically, these include preheating means for the recording head using a caving means, a cleaning means, a pressurizing or suction means, an electrothermal transducer or another heating element, or a combination thereof. It is also effective to perform a preliminary ejection mode in which ejection is performed separately from printing in order to perform stable printing.

Furthermore, the recording mode of the recording device is not limited to a recording mode for only mainstream colors such as black, but may also be configured by integrally configuring the recording head or by combining multiple pieces, but it is also possible to use multiple colors of different colors or by mixing colors. The present invention is also extremely effective for devices equipped with at least one full color image.

In the embodiments of the present invention described above, the ink has been explained as a liquid, but it has a tendency to solidify at room temperature or lower, and may be softened or liquid at room temperature, or in the above-mentioned inkjet, the ink itself is heated at 30°C or higher and 70°C. Generally, the temperature is controlled within a range of 0.degree. C. or less so that the viscosity of the ink is within a stable ejection range, so it is sufficient if the ink is in a liquid state when the recording signal is applied. In addition, it is possible to actively prevent temperature rise due to thermal energy by using it as energy to change the ink from a solid state to a liquid state, or to use ink that solidifies when left in order to prevent ink evaporation. Iruka,
In any case, some types of ink liquefy when thermal energy is applied in accordance with the recording signal and are ejected as liquid ink, and some types of ink that begin to solidify by the time they reach the recording medium, are liquefied only by thermal energy. It is also possible to use an ink having such properties that it can be used in the present invention. In such a case, the ink is held in a liquid or solid state in the recesses or through holes of the porous sheet, as described in JP-A-54-56847 or JP-A-60-71260. It may also be in a form that faces the electrothermal converter. In the present invention, the most effective method for each of the above-mentioned inks is to implement the above-mentioned film boiling method.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

Claim! In the device described in , a bypass path is provided to reduce the amount of ink supplied to the recording head, thereby reducing the amount of ink discharged from the ejection port of the J diary head when filling with ink. This has the effect of shortening the ink filling time. Furthermore, since the pressure applied to the finely formed ejection ports is also reduced, there is an effect that the life of the recording head can be extended.

In 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-mentioned effect can be further increased.

[Brief explanation of the drawing]

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 a supply recovery in the first embodiment. FIG. 4 is a flowchart showing the control operation of the supply recovery system shown in FIG. 3; FIG. 5 is a diagram showing the configuration of the supply recovery system in a second embodiment of the present invention. . DESCRIPTION OF SYMBOLS 1... Recording head unit, IA~ID-・Diary 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 pipe. 12--Return pipe, 13--Tank, 14--Non-discharge recovery device, 20A-20D--Heater 24.25--Pump, 30--Liquid chamber, 31--Discharge port, 31A--Lowest discharge port, 32--Electrothermal converter, 401-404--Valve, 101-S105--Step.

Claims (1)

[Claims] 1. A recording head that ejects and flies ink droplets from an ejection port, a tank that stores ink to be supplied to the recording head, and a recording head that is provided between the recording head and the tank, and that An inkjet recording apparatus comprising: a circulation path for circulating and supplying stored ink to a recording head; and an ink pressure feeding means provided in the circulation path for feeding and circulating ink under pressure; An inkjet recording apparatus characterized in that a circulation path between the head and the head is provided with a bypass path that bypasses the recording head. 2. The inkjet recording apparatus according to claim 1, wherein a valve is provided at a connection between the circulation path and the recording head. 3. The inkjet recording apparatus according to claim 1 or 2, wherein a valve is provided in the bypass path. 4. The ink jet recording according to claim 1, 2 or 3, wherein the recording head is a full line type in which ejection ports are formed over the entire width of the recording area of the recording sheet. Device. 5. Claim 1, wherein the recording head discharges ink using thermal energy, and is equipped with an electrothermal converter for generating the thermal energy.
4. The inkjet recording apparatus according to item 2, item 3, or item 4.