JPH03213350A - Ink jet recording device - Google Patents

Abstract

PURPOSE:To shorten the time required for refeeding ink by feeding ink to a recording head through a plurality of ink inlet and outlet ports, as feed ports, by changing over a path-changeover means in the case of a print mode and by forcibly feeding ink to said head by changing over said means in a different manner in the case of modes other than the print mode. CONSTITUTION:In the case of a print mode, a connection valve 27, valve 32 and vent value 29 are opened so that ink is fed from an ink tank 28 via ink channels 25, 26 to the opposite sides of a common liquid chamber 23. In the case of a circulation mode, the valve 27 is closed and the valves 32 and 29 are opened and a pump 31 is actuated so that the ink is sent from the tank 28 to the chamber 23 to be returned via the channel 25 to the tank 28, where bubbles are discharged into the tank 28. And in the case of a pressurizing mode, only the valve 32 is closed and the pump 31 is actuated to send the ink from the tank 28 through both feed ports 24A, 25A to the chamber 23, while the chamber 23 is pressurized to discharge the ink from a delivery port. As a result, the time required for refeeding ink can be uniformized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording device, and particularly to an inkjet recording device that is equipped with a multi-nozzle recording head, and in which circulation and pressurization of recording liquid is performed on the recording head in order to maintain performance. The present invention relates to a possible inkjet recording device.

[Prior Art] As a conventional inkjet recording apparatus of this type, there is, for example, one proposed by the applicant as disclosed in Japanese Patent Laid-Open No. 60-247564. Such a conventional inkjet recording apparatus will be explained with reference to FIG. 5. In this example, in addition to the print mode for normal recording operation, there is also a pressure mode for removing clogging in the recording head, and an inkjet recording mode for removing clogging in the recording head. The ink supply system is configured such that a circulation mode for removing air bubbles in the supply system can be set.

In FIG. 5, 101 is a recording head, 102 and 1
03 is an ink supply path to the recording head 101, 104 is a first tank, 105 is a second tank for replenishment, 106 is a pump, 107 and 108 are ink supply paths 102 and 1
03 is an on-off valve, 109 is a vent valve provided in the air vent pipe 110 of the first tank 104, and 111 is a one-way valve for replenishment. Note that the drive system for the recording head 101, the means for feeding and discharging the recording material, etc. are of general use and are not particularly illustrated.

Table 3 shows the states of the valves 107, 108, 109 and the pump 106 in various modes of the ink supply system set in the inkjet recording apparatus configured as described above.

(Margin below) Table 3 As is clear from Table 3, in the ink supply system of this example, valves 107, 108, 109 and pump 1
By operating 06, it is possible to switch to circulation, pressurization, and storage modes in addition to print mode, and expect the effects of each mode. Also, when refilling ink,
By closing the valve 108 and driving the pump 106 in the F direction, ink can be supplied from the second tank 105 to the first tank 104 via the one-way valve Ill.

[Problems to be Solved by the Invention] However, in the above-described conventional inkjet recording apparatus, in the print mode, the path for supplying ink to the recording head 101 is only on the ink supply path 102 side. In this case, there is a difference between the ejection characteristics from an ejection port (not shown) located closer to the supply port and the ejection characteristics from an ejection port (not shown) located farther from the supply port, for example, when ink is ejected. The refilling time is different as shown in Figure 6, and the refilling time TI on the side farther from the supply port is different from the refill time TI at the nozzle A on the side closer to the supply port. The refilling time T2 in nozzle B takes a long time. Therefore, the highest driving frequency when driving the recording head 101 is determined by the refilling time T2, which takes longer, and there is a drawback that the recording speed is restricted accordingly.

The purpose of the present invention is to eliminate the conventional drawbacks as mentioned above,
An object of the present invention is to provide an inkjet recording device that can shorten ink refill time in a recording head and realize high-frequency drive.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a multi-nozzle recording head having a plurality of ink inlets and outlets through which ink can flow, and a system for storing ink to be supplied to the recording head. an ink tank capable of supplying the ink from the ink tank to the recording head via the plurality of ink inlets and outlets; An ink feeding path for forcibly feeding the ink; and an ink distribution path are provided, and the supply of the ink to the plurality of ink ports can be switched to forced feeding by the ink feeding path. The device is characterized in that it has a route switching means.

[Function] According to the present invention, in the print mode, by switching the path switching means, the plurality of ink inlets and outlets are used as supply ports.
Ink can be supplied to the recording head, which reduces the delay in refilling the ink even for liquid paths that are far from the multi-nozzle meat supply port, and in other modes, it is possible to By switching the switching means to the other side, ink can be forcibly sent to the recording head, and circulation and pressurizing operations can be performed on the recording head.

[Examples] Examples of the present invention will be described below in detail and specifically based on the drawings.

FIG. 1 shows the configuration of an ink supply system as an embodiment of the present invention, and FIG. 2 shows the overall configuration of the inkjet recording apparatus of the present invention. First, in FIG. 2, reference numeral 1 denotes a bubble jet type recording head, and in this example, each of the plurality of recording heads 1 has 4736 ink ejection ports (not shown) arranged at a density of 400 dpi. In addition, each recording head l is provided with a heating resistor in order to generate ejection energy in a liquid path communicating with its ejection opening, and when energized, bubbles are generated in the ink that remains in contact with the heating resistor. Ink is ejected from the ejection port using pressure. 2
3 is a holding block that holds a plurality of recording heads, and 3 is a capping unit. During recording standby, the holding block 2 is pulled up to the position indicated by the dashed line and its ejection surface side is capped with the capping unit 3. Further, during circulation recovery, ink is sent to the recording head 1 via an ink supply system by a recovery pump (described later), and a tray serves as a receiver for waste ink discharged from the ejection ports. Note that the waste ink is led to a waste ink tank (not shown).

Reference numeral 4 denotes an endless charging adsorption belt which is disposed opposite to the ejection surface of the recording head l with a predetermined distance therebetween, and reference numeral 5 is a back platen which is arranged at a position facing the head 1 via the charging adsorption belt 4. It is. 6 is recording sheet 7 such as plain paper
A paper feed cassette is housed therein and is detachably attached to the main body. Reference numeral 8 is a pickup roller that feeds out only one recording sheet 7 on the uppermost surface. 9 is a conveyance roller that sends out the recording sheet 7 sent out from the pickup roller 8 to the conveyance path 10, and 11 is a conveyance roller disposed on the sending side of the conveyance path IO. 13 and 14 are heaters and fans that dry and fix droplets flying onto the surface of the recording sheet 7 using hot air; 15 is a discharge roller that discharges the recording sheet 7 after fixing to the outside of the apparatus; 16 is a discharged recording sheet 7
This is a tray for sequentially stocking.

Next, the operation of such an inkjet recording apparatus will be explained.

First, the recording operation will be explained. When an operation to start recording is performed, a recording sheet 7 of a specified size is sent out from the paper feed cassette 6 by a pickup roller 8. The fed recording sheet 7 is rotated in a pre-charged state by transport rollers 9 and 11 and is placed on the charged adsorption belt 4 which is held flat by the back platen 5. When the leading edge of the recording sheet 7 reaches the lower part of the head 1, it moves, and a recording processing device (not shown) operates to drive the energy generator of the head 1, and this movement causes the document information to be changed. Accordingly, droplets are ejected from the ejection ports toward the surface of the recording sheet 7, and recording is performed. Note that if the recording sheet 7 has poor hygroscopicity, the droplets adhering to the surface will not dry and will be rubbed and cause print stains, so the heater 13 and the fan 14 are used to forcefully dry the print and fix it. The recording sheet 7 that has been fixed is discharged onto a tray 16 by a discharge roller 15.

Next, the configuration of the ink supply system according to the present invention will be explained with reference to FIG.

The multi-nozzle recording head 1 has a plurality of liquid channels 22 separated by partition walls 21 and a common liquid chamber 23 that communicates with these liquid channels 22, and the individual liquid channels 22 are not shown here either. As mentioned earlier, a heating resistor is provided. 24 and 25 are first and second ink passages connected to substantially both ends of the common liquid chamber 23; 26 is the ink passage 2;
4 and 25, and 27 is a valve provided in the communicating ink passage 26 (hereinafter referred to as a communicating valve). 28
29 is an ink tank, 29 is a vent valve installed in the air vent pipe 30,
31 is a pump that sends ink from the ink tank 28 to the first ink passage 24, and 32 is a valve provided at the rising portion 25B of the second ink passage 25 from the tank 28. In addition,
These valves 27, 29 and 32 are preferably, for example, electromagnetic valves so that their opening and closing can be easily controlled.

Table 1 shows the states of the valves and pumps in each mode in the ink supply system configured as described above.

Table 1 Next, the ink distribution path in each mode will be explained according to Table 1.

(1) Print mode Note that this example shows an example applied to an on-demand type inkjet recording device. Therefore, there is no need to apply pressure to the ink supplied to the recording head 1 during recording, and the pump is stopped. has been done. In this mode, the communication valve 27, the valve 32, and the ventilation valve 29 are all open, and ink flows from the ink tank 28 through the second ink passage 25 and the communication ink passage 26 into the common liquid chamber 23. is fed by passages 24 as well as passages 25 from both sides. For this purpose, as shown in FIG. 3, the common liquid chamber 23 is refilled through the liquid paths C and D near the ink inlets and outlets (supply ports) 24A and 25A on both sides, and the liquid path E located in the middle thereof. The difference between times T1 and T3 can be small.

(2) Circulation mode By circulating the ink in the print head 1, air bubbles are removed from the print head and the ink supply system before the printing apparatus starts printing, and the ink in the ink supply system is refreshed. This mode is used to replace a new one, and is especially set when the recording device has been left unused for a long time. In this circulation mode, as shown in Table 1, the communication valve 27 is closed and the pump 3 is opened with the valve 32 and the ventilation valve 29 open.
1, the ink is sent from the ink tank 28 to the common liquid chamber 24 of the recording head 1 through the first ink passage 24, and the ink is returned to the ink tank 28 through the second ink passage 25, thereby circulating the ink. With,
Air bubbles trapped during this time can be released within the ink tank 28.

(3) Pressure mode When the liquid path 22 or ejection port of the recording head 1 becomes clogged, pressure is applied to the ink to forcibly push the ink out of the ejection port to expel the clogged foreign matter. mode. In this pressurizing mode, only the valve 32 of the second ink passage is closed and the pump 31 is driven, as shown in Table 1. In this way, the ink sucked from the ink tank 28 via the first ink passage 24 is transferred to the supply ports 24A and 25 via the communicating ink passage 26.
Ink can be fed into the common liquid chamber 23 from both sides of A and pressure can be applied, and the ink can be forcibly discharged from the ejection ports by the liquid pressure.

FIG. 4 shows the configuration of an ink supply system according to a second embodiment of the present invention. In this example, instead of providing a communication passage and a communication valve between the first ink passage 24 and the second ink passage 25, a bypass passage 36 is provided between the upstream side and the downstream side of the pump 31 of the first ink passage 24. Bypass valve 37 in bypass passage 36
It has been established.

Table 2 shows the states of the valves and pumps in each mode in the ink supply system of this embodiment.

Table 2 Note that the explanation of the operation in each mode according to this embodiment will be omitted, but this embodiment is particularly characterized by the provision of a bypass valve 37 that is closed when the pump 31 is in operation. The bypass valve 37 can be replaced by a one-way check valve that only allows flow in the direction of the arrow.

Note that although the above-described embodiment deals with the case where there are two ink passages to the recording head, the number of ink passages is not limited to two (for example, there are three ink passages for a multi-nozzle recording head). It goes without saying that the present invention can also be applied to an inkjet recording device equipped with the above ink passage.Also, the valve provided in the ink passage is not limited to a solenoid valve, but may be a valve whose opening/closing is appropriately controlled. Any valve may be used.

It should be noted that the present invention provides excellent effects particularly in bubble jet recording heads and recording apparatuses among ink jet recording systems.

This is because such a system can achieve higher recording density and higher definition, and it is expected that the fixing speed will be even slower depending on the recording pattern.

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. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, it is necessary to arrange the liquid (ink) in accordance with the sheet and liquid path that hold it. The electrothermal converter that is
Generating thermal energy in the electrothermal transducer and producing film boiling on the thermally active surface of the recording head by applying at least one drive signal that corresponds to recorded information and provides a rapid temperature rise above nucleate boiling. As a result, bubbles in the liquid (ink) can be formed in one-to-one correspondence with this drive signal, which is effective. The growth and contraction of the bubble causes liquid (ink) to be ejected through the ejection opening to form at least one droplet. If this drive signal is in the form of a pulse, bubble growth and contraction will occur immediately and appropriately.
Particularly responsive liquid (ink) ejection can be achieved,
More preferred. This pulse f+3. As the drive signal, US Pat. No. 4,463,359 and US Pat.
262 is suitable. Furthermore, if the conditions described in US Pat. No. 4,313,124 concerning the invention regarding the temperature increase rate of the heat acting surface are adopted, even more excellent recording can be performed.

As for the structure of the recording head, there is a method disclosed in Japanese Patent Application Laid-open No. 59-123670 which discloses a structure in which a common slit is used as a discharge part for a plurality of electrothermal transducers, and a method that absorbs pressure waves of thermal energy. The effects of the present invention are also effective even with a configuration based on Japanese Patent Application Laid-Open No. 138461/1983, which discloses a configuration in which the openings correspond to the discharge portions.

Furthermore, the present invention can be particularly effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium that can be recorded by a recording apparatus. Such a recording head may have a configuration in which the length is satisfied by a combination of multiple recording heads, or a configuration as a single recording head formed integrally. As for the number or number of inks, for example, only one ink may be provided corresponding to a single color ink, or a plurality of ink may be provided corresponding to a plurality of inks having different recording colors or densities.

In addition, the inkjet recording apparatus of the present invention can be used as an image output terminal for information processing equipment such as a computer, or as a copying apparatus combined with a reader or the like, or as a facsimile apparatus having a transmitting and receiving function. It may also be one that takes

[Effects of the Invention] As described above, according to the present invention, ink can be supplied to the recording head through a plurality of ink inlets and outlets by keeping the path switching means provided in the ink distribution path open. This makes it possible to prevent uneven refilling times for the multiple liquid paths in a multi-nozzle recording head, and to prevent the dots from differing in diameter in the recorded image or when ink is ejected after being left unused. It is possible to prevent the ejection characteristics from being impaired and improve reliability.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an ink supply system according to a first embodiment of the present invention, Fig. 2 is a block diagram of an inkjet recording apparatus to which the present invention is applied, and Fig. 3 is a characteristic curve diagram of ink refill time according to the present invention. , FIG. 4 is a block diagram of an ink supply system according to a second embodiment of the present invention, FIG. 5 is a block diagram of an ink supply system according to a conventional example, and FIG. 6 is a diagram showing the characteristic curve of ink refilling time according to a conventional example. It is a diagram. DESCRIPTION OF SYMBOLS 1... Recording head, 22... Liquid path, 23... Common liquid chamber, 24, 25... Ink passage, 24A, 25A... Ink (supply port) 26... Communication ink passage, 27...Communication valve, 28...Ink tank, 29...Vent valve, 31...Pump, 32...Valve, 36...Bypass passage, 37...Bypass valve. Entrance/exit, E 1 Kusame-Moon IJ O Influenza 1 Light Angle Awakening J Introduction E Tsukuda Group Arrangement 4 Fig. 5

Claims (1)

[Scope of Claims] 1) A multi-nozzle recording head having a plurality of ink inlets and outlets through which ink can flow, an ink tank that stores ink to be supplied to the recording head, and a multi-nozzle recording head having a plurality of ink inlets and outlets through which ink can flow. an ink distribution path that can supply the ink from the ink tank to the recording head; and an ink supply that forcibly supplies the ink from the ink tank to at least one of the plurality of ink ports via a pump. an inkjet recording apparatus, comprising: a path; and a path switching means provided in the ink distribution path and capable of switching the supply of the ink to the plurality of ink inlets and outlets to forced feeding through the ink feeding path. .