JPH03234651A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To enable high speed printing to be performed and to prevent discharge responsibility of ink, discharge efficiency and discharge stability from decreasing by a method wherein a friction head of a first ink part is made less than a friction head of a second ink path. CONSTITUTION:An ink cartridge 34 for supplementing ink to an ink supply tank 33 supplies ink to a common liquid chamber 30a of a recording head 30 by a supply tube 31 being a first ink path from the ink supply tank 33. Further, when ink is supplemented, ink can be supplemented to the ink supply tank 33 by applying a chicken feed principle from the ink cartridge 34. Furthermore, a recovery pump 35 to be used in discharge function recovery operation of the recording head 30 is interconnected to the recording head 30 with a circulating tube 32 being a second ink path. Then, a length of the supply tube 31 is approximate a half of a length of the circulating tube 32, and an inner diameter of the supply tube 31 is equal to an inner diameter of the circulating tube 32. Thereby, a friction head of the supply tube 31 becomes approx. one half of the friction head of the circulating tube 32.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording apparatus that performs recording by ejecting ink.

[Prior Art] Non-impact recording methods have recently attracted attention because the noise generated during recording is so small that it can be ignored. Among these, the inkjet recording method is an extremely powerful recording method that has the possibility of high-speed recording.

A recording head applied to an inkjet recording device generally includes a fine liquid ejection opening, a liquid flow path, an energy application section provided in a part of the liquid flow path, and a droplet forming device that acts on the liquid in the energy application section. It is equipped with an energy generation means for generating energy.

Energy generating means for generating such energy include recording methods using electromechanical transducers such as piezo elements, irradiating electromagnetic waves such as lasers, absorbing them into the liquid and generating heat, and the effect of the heat generated. There are recording methods that use energy generating means to eject and fly droplets, or recording methods that use energy generating means that heats the liquid with an electrothermal converter and ejects the liquid.

Among these, the recording head used in the jet recording method uses thermal energy to eject liquid, and has a high density array of liquid ejection ports that eject recording droplets to form flying droplets. This makes it possible to record with high resolution. Among these, a recording head that uses an electrothermal converter as an energy generating means is easy to downsize as a whole as a recording head, and is based on the IC technology and microelectronic technology, which has made remarkable advances in technology and reliability in the semiconductor field in recent years. It can take full advantage of the advantages of processing technology, and it is easy to make it long and planar (two-dimensional), so it is easy to use multi-nozzles and high-density packaging, and it can be produced in large quantities with good productivity. , it is possible to provide an inkjet recording head with low manufacturing cost. As described above, an inkjet recording head manufactured through a semiconductor manufacturing process using an electrothermal converter as an energy generating means generally has a liquid flow path corresponding to each liquid ejection port.
An electrothermal transducer is provided for each liquid flow path as a means for applying thermal energy to the liquid filling the liquid flow path and ejecting the liquid from the corresponding liquid ejection port to form flying droplets, Each liquid flow path is configured to be supplied with liquid from a common liquid chamber communicating with each liquid flow path.

An example of a recording head having such a configuration is shown in FIG.

Reference numeral 1 denotes a so-called full-line type recording head in which ink ejection ports are provided over the entire width of a recording area of a recording material (not shown). 8 is a common liquid chamber in the recording head 1, 10a
are a plurality of ink ejection ports arranged on the ink ejection surface 11a. Ink can be ejected by selectively driving heating elements provided in liquid paths (not shown) leading to the individual ink ejection ports 10a. 22 is an ink supply tank that supplies ink to the recording head 1, and from the ink supply tank 22 there is a supply pipe 25 that is a first ink path.
Accordingly, ink can be supplied to the common liquid chamber 8 of the recording head 1. Further, reference numeral 27 denotes a recovery pump used during a recovery operation to restore the ejection function of the recording head l, and this recovery pump 27 is communicated with the recording head l through a circulation pipe 26 which is a second ink path. . The lengths of the above-mentioned supply pipe 25 and circulation pipe 26 are approximately equal to each other,
Moreover, their inner diameters are also equal.

In the recording head 1 and its ink supply system and recovery system configured in this way, during recording, the ink supply tank 2
-2, the ink is replenished into the common liquid chamber 8 through the ink supply pipe 25 due to its own weight, and is guided from the common liquid chamber 8 to the ink discharge port 10a via a liquid path (not shown). In addition, during a recovery operation performed to remove air bubbles remaining in the common liquid chamber 8 and the supply system and to cool the recording head l, the recovery pump 27 is activated to supply ink to the common liquid chamber 8 through the circulation pipe 26. The ink can be returned to the ink supply tank 22 from the common liquid chamber 8 through the supply pipe 25 and circulated. Furthermore, at the time of initial filling of the liquid path, etc., the recovery pump 27 can force-feed the ink to the common liquid chamber 8 via the circulation pipe 26, and discharge the ink from the ink discharge port 10a while discharging air bubbles.

Although the above-mentioned recording head uses an electrothermal transducer as an energy generating means, an inkjet recording device equipped with an electromechanical transducer such as a piezo element or a recording head that uses electromagnetic waves such as a laser may also be used. The present invention described below can also be applied to the following.

[Problems to be Solved by the Invention] However, when using such a full-line type recording head, a large amount of ink is consumed due to the aim of high-speed recording or long-term continuous recording, so the ink supply status must be controlled. It is necessary to achieve stabilization.

However, the amount of ink supplied from the supply tube to the recording head was not sufficient to achieve high-speed recording.

The present invention has been made in view of the above-mentioned problems of the conventional technology, and even when a full-line type print head is used, there is no shortage of ink supply to the print head during printing. An object of the present invention is to provide an inkjet recording device that is capable of high-speed recording and does not deteriorate ink ejection response, ejection efficiency, and ejection stability.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a recording head and an ink supply tank storing ink to be supplied to the recording head in a first ink path and a second ink path. In the inkjet recording apparatus connected by , a friction head loss in the first ink path is smaller than a friction head loss in the second ink path.

Further, the first ink path has an ink flow direction during recording, and
The ink flow direction during the recovery operation of the recording head is the opposite direction.

Furthermore, the length of the first ink path is shorter than the length of the second ink path.

The inner diameter of the first ink path is larger than the inner diameter of the second ink path.

Further, the recording head is a full-line type recording head in which ink ejection ports are formed over the entire recording width of the recording material.

Further, the recording head ejects ink using thermal energy, and includes an electrothermal converter that generates the thermal energy.

[Operation] The friction loss head (pressure loss head) h of a circular pipe can generally be expressed by the following equation (1).

Here, λ is the tube friction coefficient, °C is the length of the circular tube, d is the inner diameter of the circular tube, ■ is the flow rate of the fluid (ink), and g is the gravitational acceleration.

The present invention solves the above equation (1) by making the length of the first ink path shorter than that of the second ink path, or by making the inner diameter of the first ink path larger than that of the second ink path. Based on this, the friction loss head of the first ink path is set smaller than that of the second ink path. As a result, during recording, the ink in the ink supply tank is
The ink is easily guided to the recording head through the ink path, and the amount of ink that is guided is ic! The amount of ink ejected by the recording head can be sufficiently compensated for. Therefore, even when using a full-line type recording head that consumes a large amount of ink, there is no shortage of ink supply.

[Example] Next, an example of the present invention will be described with reference to the drawings. In each embodiment, the same reference numerals are used for parts having the same structure.

(First Embodiment) In FIG. 1, 30 is a full-line type recording head (hereinafter referred to as a "recording head"), and 30a is a recording head 3.
A common liquid chamber 37 in 0 is a plurality of ink ejection ports arranged on the ink ejection surface 36. Therefore, the number of ink ejection ports 37 in this example is arranged to cover the entire recordable width of the target recording material (not shown), and the number of ink ejection ports 37 that are connected to each ink ejection port 37 is not shown. Ink is ejected by selectively driving heating elements provided in the liquid path, and printing can be performed without main scanning of the head itself. 33 is an ink supply tank that stores ink to be supplied to the recording head 30; 34 is an ink supply tank 3;
This is an ink cartridge for replenishing ink to the recording head 30, and the ink is supplied from the ink supply tank 33 to the common liquid chamber 30a of the recording head 30 through the supply pipe 31, which is the first ink path.
Furthermore, when replenishing ink, the ink supply tank 33 can be replenished with ink from the ink cartridge 34 by applying the principle of chicken feed. Also, 3
A recovery pump 5 is used during a recovery operation to restore the ejection function of the recording head 30, and this recovery pump 35 is communicated with the recording head 3o through a circulation pipe 32, which is a second ink path. Further, the length of the supply pipe 31 mentioned above is approximately half the length of the circulation pipe 32, and the inner diameter of the supply pipe 31 is equal to the inner diameter of the circulation pipe 32. As a result, the friction head loss in the supply pipe 31 is approximately half that of the circulation pipe 32.
become.

In the recording head 30 and its ink supply system and recovery system configured in this way, during recording, the common liquid chamber 30a is sufficiently replenished with ink from the ink supply tank 33 due to the weight of the liquid, and no ink is discharged from the common liquid chamber 30a. The ink is guided to the ink discharge port 37 via the illustrated liquid path. In addition, during a recovery operation performed to remove air bubbles remaining in the common liquid chamber 30a and the supply system and to cool the recording head 30, the recovery pump 3
5 to supply ink to the common liquid chamber 30 via the circulation pipe 32.
a, and the ink can be returned to the ink supply tank 33 from the common liquid chamber 30a through the supply pipe 31 and circulated. Furthermore, at the time of initial filling of the liquid path, etc., the recovery pump 35 can force-feed the ink to the common liquid chamber 30a through the circulation pipe 32, and discharge the ink from the ink discharge port 37 while discharging air bubbles.

In this embodiment, the friction head loss of the supply pipe 31 is about half that of the circulation pipe 32, so during recording, ink in the ink supply tank 33 is guided to the recording head 30 through the supply pipe 31. Becomes easily irritated. As a result, the amount of ink guided to the recording head 30 through the supply pipe 31 can sufficiently compensate for the amount of ink ejected by the recording head 30.
No shortage of ink supply occurs.

Next, an inkjet recording apparatus equipped with the above-described ink supply system and recovery system will be described.

42 is a part of a scanner that reads a document 46a to be copied and converts it into an electrical signal, and the signal is sent to the printer section 4.
3 as a drive signal. The paper feed cassette 45a stores recording paper as the recording material at that time, and the recording paper is sent out one by one toward the belt transport section 40 by the transport means 45b when necessary. When this recording paper passes through the belt conveying section 40, a printed image is recorded by the recording head section 38, and the paper is sent out to the tray 41 by the discharging means 46 via the fixing paper discharging section 44. Further, 39 is a recovery cap section, which has a function to maintain the recording head section 38 in a state where printing is possible at all times. On the other hand, ink cartridges 34 for each color of cyan, macenta, yellow, and black ink are provided, and ink is supplied from each of the four ink supply tanks 33 to the recording head section 38. In addition, in the figure, 46b indicates a figure number reading means.

(Second Embodiment) In this embodiment, as shown in FIG.
The inner diameter of a is approximately twice the inner diameter of the circulation pipe 32, and the other configurations are the same as those of the first embodiment.

In this embodiment, the frictional head loss of the supply pipe 31a is about one-fourth of that of the circulation pipe 32, so during recording, ink is guided from the ink supply tank 33 to the recording head 30 through the supply pipe 31a. Since the amount can more fully compensate for the amount of ink ejected from the recording head 30, insufficient supply of ink can be prevented.

In both of the above embodiments, the present invention is applied to an inkjet recording device equipped with four ink supply tanks, but the present invention is not limited to this, and the present invention is applied to an inkjet recording device equipped with one ink supply tank. You may.

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. 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. 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 acting surface of the liquid (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. It is more preferable to use this drive signal in a pulse form, since the growth and contraction of bubbles can be carried out immediately and appropriately, so that ejection of liquid (ink) with particularly excellent responsiveness can be achieved. 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 be configured using the specification. In addition, JP-A No. 123670 of 1982 discloses a configuration in which a common slit is used as a discharge part of the electrothermal converters for a plurality of electrothermal converters.
No. 138461 of 1982, which discloses a configuration in which a discharge portion has an opening that absorbs pressure waves of thermal energy.
The present invention is also effective with a configuration based on the 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. Either a configuration that satisfies the above requirements or a configuration as a single recording head formed integrally may be used, but the present invention can more effectively exhibit the above-mentioned effects.

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 in which only the mainstream color such as black is used; the recording head may be configured integrally or in combination with a plurality of recording heads; The present invention is also extremely effective for devices equipped with at least one of full colors.6 [Effects of the Invention] Since the present invention is configured as described above, it is possible to create an inkjet recording device that exhibits the effects described below. Can be provided.

During printing, the amount of ink guided from the ink supply tank to the print head through the first ink path can sufficiently compensate for the amount of ink ejected by the print head, so it is not possible to use a full-line type print head that consumes a large amount of ink. Even when used, insufficient supply of ink can be prevented, and ink ejection responsiveness, ejection efficiency, and ejection stability do not deteriorate.

[Brief explanation of drawings]

FIG. 1 is a front view of an ink supply system and an ink recovery system of a first embodiment of an inkjet recording apparatus according to the present invention;
The figure is a schematic configuration diagram of the first embodiment, FIG. 3 is a front view of the ink supply system and ink recovery system of the second embodiment of the present invention, and FIG.
The figure shows a conventional example, and is a configuration diagram of an ink supply system and an ink recovery system of an inkjet recording apparatus. 30... Recording head, 30a... Common liquid chamber, 31.31a... Supply pipe, 32... Circulation pipe, 33... Ink supply tank, 34. ...Ink cartridge, 35...
・Recovery pump, 36...Ink ejection surface, 37...Ink ejection port, 38...Record head section, 39...Recovery cap section, 40. ...Belt transport section, 41...Tray, 42...Canner part, 43...Printer section, 44...Fixing sheet discharge section , 45a...Paper feed cassette, 45b...Transporting means, 46...Ejecting means, 46a...Document, 46b...Picture number reading means.

Claims (1)

[Scope of Claims] 1. An inkjet recording apparatus in which a recording head and an ink supply tank storing ink to be supplied to the recording head are connected by a first ink path and a second ink path, comprising: An inkjet recording apparatus characterized in that a friction head loss in the path is smaller than a friction head loss in the second ink path. 2. The inkjet recording apparatus according to claim 1, wherein in the first ink path, the ink flow direction during recording is opposite to the ink flow direction during recovery operation of the recording head. 3. The inkjet recording apparatus according to claim 1 or 2, wherein the length of the first ink path is shorter than the length of the second ink path. 4. The inkjet recording apparatus according to claim 1, 2 or 3, wherein the inner diameter of the first ink path is larger than the inner diameter of the second ink path. 5. The inkjet recording apparatus according to claim 1, wherein the recording head is a full-line type recording head in which ink ejection ports are formed over the entire recording width of the recording material. 6. The recording head according to claim 1, 2, 3, 4, or 5, wherein the recording head discharges ink using thermal energy, and includes an electrothermal converter for generating the thermal energy. Inkjet recording device.