JP2752495B2 - Ink jet recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording apparatus that performs recording by discharging ink.

2. Description of the Related Art The non-impact recording method has recently attracted attention in that noise during recording is extremely small to a negligible level. Among them, an ink jet recording method capable of performing recording with a possibility of high-speed recording is an extremely effective recording method.

The recording head applied to the ink jet recording apparatus includes:
In general, there are provided a fine liquid discharge port, a liquid flow path, an energy action section provided in a part of the liquid flow path, and energy generation means for generating droplet forming energy to act on the liquid in the energy action section. .

As an energy generating means for generating such energy, a recording method using an electromechanical transducer such as a piezo element, irradiating an electromagnetic wave such as a laser, absorbing the liquid there to generate heat, and acting by the heat generation To eject droplets,
There is a recording method using an energy generating means for flying, or a recording method using an energy generating means for heating a liquid by an electrothermal converter to discharge the liquid. Among them, a recording head used in an ink jet recording method that uses a thermal energy to discharge a liquid has a high density of liquid discharge ports for discharging a recording liquid droplet and forming a flying liquid droplet. This makes it possible to record at a high resolution. Among them, a recording head using an electrothermal transducer as an energy generating means can easily be made compact as a recording head as a whole, and has recently achieved remarkable advances in technology in the field of semiconductors, such as IC technology and microtechnology. It is possible to make full use of the advantages of processing technology, and it is easy to make it multi-nozzle and high-density mounting because it is easy to make it longer and more planar (two-dimensional). In addition, it is possible to provide an ink jet recording head whose production cost is low. in this way,
Using an electrothermal transducer for the energy generating means, an ink jet recording head manufactured through a semiconductor manufacturing process is generally provided with a liquid flow path corresponding to each liquid ejection port,
An electrothermal converter is provided for each of the liquid flow paths as a means for applying thermal energy to the liquid filling the liquid flow path to discharge the liquid from the corresponding liquid discharge port to form a droplet for flight. Liquid is supplied to each liquid flow path from a common liquid chamber communicating with each liquid flow path.

 FIG. 4 shows an example of a recording head having such a configuration.

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. The ink can be ejected by selectively driving a heating element provided in a liquid path (not shown) communicating with each ink ejection port 10a. Reference numeral 22 denotes an ink supply tank that supplies ink to the recording head 1. The ink can be supplied from the ink supply tank 22 to the common liquid chamber 8 of the recording head 1 by a supply pipe 25 that is a first ink path. Also, 27
A recovery pump 27 is used at the time of a recovery operation for recovering the ejection function of the recording head 1.
Is connected to the recording head 1 by a circulation pipe 26 as a second ink path. The lengths of the supply pipe 25 and the circulation pipe 26 are substantially equal to each other, and their inner diameters are also equal.

In the recording head 1 and its ink supply system and recovery system configured as described above, the ink supply tank
Ink is supplied to the common liquid chamber 8 from the common liquid chamber 8 via the ink supply pipe 25 by its own weight from the liquid 22, and is guided from the common liquid chamber 8 to the ink discharge port 10a via a liquid path (not shown). Also, the common liquid chamber 8
During the recovery operation performed to cool the recording head 1 together with the removal of air bubbles remaining in the supply system and the supply system, the recovery pump 27 is used.
Is started, the ink is sent to the common liquid chamber 8 by the circulation pipe 26, and the ink is returned from the common liquid chamber 8 to the ink supply tank 22 by the supply pipe 25 to be circulated. Further, at the time of initial filling of the liquid path and the like, the ink can be pressure-fed to the common liquid chamber 8 via the circulation pipe 26 by the recovery pump 27, and the ink can be discharged from the ink discharge port 10a together with the discharge of the bubbles.

Although the above-described recording head using an electrothermal converter for energy generation means has been described in detail, an inkjet recording apparatus including a recording head using an electromagnetic wave such as an electromechanical converter such as a piezo element or a laser or the like may be used. Also, the present invention described below can be applied.

[Problems to be Solved by the Invention] However, when such a full-line type recording head is used, a large amount of ink is consumed in order to achieve high-speed printing or continuous printing for a long time. Stabilization must be achieved.

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

The present invention has been made in view of the problems of the above-described conventional technology, and even when using a full-line type recording head, at the time of recording, there is no shortage of ink supply to the recording head, It is an object of the present invention to provide an ink jet recording apparatus which can perform high-speed recording and does not deteriorate the ejection response, ejection efficiency and ejection stability of ink.

Means for Solving the Problems To achieve the above object, the present invention provides a recording head comprising:
An ink supply tank for storing ink to be supplied to the recording head is connected by a first ink path and a second ink path, and a pump is provided in the second ink path; In a non-operating state of the pump, an ink supply flow from the ink supply tank to the recording head via the first ink path occurs, and at the time of the recovery operation of the recording head, the operation of the pump causes the ink supply tank to return from the ink supply tank. An ink jet recording apparatus in which an ink circulation flow which reaches the recording head via a second ink path and further returns to the ink supply tank via the first ink path occurs, wherein a frictional loss head of the first ink path is: The friction loss head of the second ink path is smaller than the head.

Further, 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.

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

Here, λ is the pipe friction coefficient, l is the length of the circular pipe, d is the inner diameter of the circular pipe, v is the flow velocity of the fluid (ink), and g is the gravitational acceleration.

According to the present invention, the length of the first ink path is made shorter than that of the second ink path, or the inner diameter of the first ink path is made larger than that of the second ink path. , The frictional loss head of the first ink path is set smaller than that of the second ink path. This makes it easier for the ink in the ink supply tank to be guided to the print head through the first ink path during printing,
The amount of ink guided can sufficiently supplement the amount of ink ejected by the recording head. Therefore, even when a full line type recording head that consumes a large amount of ink is used, there is no shortage of ink supply. Furthermore, when the recovery operation is performed, a good ink circulating flow without ink stagnation in the print head can be formed, and excessive inflow of ink into the print head can be prevented, so that ink is wasted from the ink discharge ports. Does not leak to

Example Next, an example of the present invention will be described with reference to the drawings. The same reference numerals are used for those having the same structure in each embodiment.

(First Embodiment) In FIG. 1, reference numeral 30 denotes a full-line type recording head (hereinafter, referred to as a “recording head”), reference numeral 30 a denotes a common liquid chamber in the recording head 30, and reference numeral 37 denotes a plurality of ink ejection surfaces 36. Are the ink ejection ports. Thus, the ink ejection port 37 of this example is
The number of ink ejection ports is arranged over the entire recordable width of a target recording material (not shown).
By selectively driving a heating element provided in a liquid path (not shown) leading to 37, ink can be ejected, and printing can be performed without main scanning of the head itself. Reference numeral 33 denotes an ink supply tank for storing ink to be supplied to the recording head 30, and reference numeral 34 denotes an ink cartridge for replenishing the ink supply tank 33 with ink.
The ink is supplied to the common liquid chamber 30a of the recording head 30 from the supply pipe 31 which is the first ink path, and at the time of ink replenishment, the principle of chicken feed is applied from the ink cartridge 34 to the ink supply tank 33. Ink can be replenished. A recovery pump 35 is used at the time of a recovery operation performed for recovering the ejection function of the recording head 30. The recovery pump 35 is a circulation pipe 32 serving as a second ink path.
Through the recording head 30. The length of the supply pipe 31 is approximately half the length of the circulation pipe 32,
Is equal to the inner diameter of the circulation pipe 32. As a result, the friction loss head of the supply pipe 31 is about one half that of the circulation pipe 32.

In the recording head 30 and its ink supply system and recovery system configured as described above, the ink supply tank
The ink is sufficiently supplied to the common liquid chamber 30a by the weight of the liquid from the liquid 33, and is guided from the common liquid chamber 30a to the ink discharge port 37 via a liquid path (not shown). Further, at the time of the recovery operation performed to cool the recording head 30 together with the removal of the air bubbles remaining in the common liquid chamber 30a and the supply system, the recovery pump 35 is activated to supply the ink to the common liquid chamber 30a by the circulation pipe 32. The ink is supplied from the common liquid chamber 30a to the ink supply tank 3 by the supply pipe 31.
It can be returned to 3 and circulated. Furthermore, at the time of initial filling of the liquid path and the like, ink can be pressure-fed to the common liquid chamber 30a via the circulation pipe 32 by the recovery pump 35, and the ink can be discharged from the ink discharge port 37 together with the discharge of bubbles.

In this embodiment, the friction loss head of the supply pipe 31 is the circulation pipe.
Since it is about one half of that of 32, at the time of recording, the ink in the ink supply tank 33 is easily guided to the recording head 30 through the supply pipe 31. 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, so that insufficient ink supply does not occur. When the recovery operation is performed in the present embodiment, the pump operates to reach the recording head from the ink supply tank via the second ink path, to take in bubbles and the like in the recording head into the ink, and further to the first ink path. Circulates back to the ink supply tank. Then, the bubbles are removed from the ink by flowing upward in the ink supply tank. In this recovery operation, if the amount of ink flowing from the ink supply tank to the recording head via the second ink path is too large, not only does the ink flow through the recording head to the first ink path, but also from the ink discharge port to the outside. And may be wasted. However, according to the present invention, since the frictional head of the second ink path is large, it is possible to prevent the ink from excessively flowing into the recording head during the recovery operation. Further, since the frictional loss head in the first ink path is small, the flow of the ink returning from the recording head to the ink supply tank is smooth, and there is no possibility that the ink stagnates in the recording head and overflows from the ink ejection port. Therefore, wasteful consumption of ink is hindered. Further, as described above, at the time of recording, a sufficient amount of ink can be supplied to the recording head via the first ink path having a small frictional loss head. Since the pump does not operate at the time of recording, the ink is slightly supplied from the ink supply tank to the recording head via the second ink path. However, sufficient ink is supplied by the ink supply from the first ink path. Therefore, the magnitude of the frictional loss head in the second ink path hardly affects the ink supply during recording.

Next, an ink jet recording apparatus having the above-described ink supply system and recovery system will be described.

Reference numeral 42 denotes a scanner unit which reads a document 46a to be copied and converts it into an electric signal. The signal is supplied as a drive signal to a recording head unit 38 of a printer unit 43. The recording paper as a recording material at that time is stored in the paper feed cassette 45a, and the recording paper is sent out to the belt conveyance unit 40 one by one as needed by the conveyance means 45b. When the recording paper passes through the belt transport unit 40, a print image is recorded by the recording head unit 38, and the recording paper is discharged through a fixing discharge unit 44.
It is sent to the tray 41 by 46. Reference numeral 39 denotes a recovery cap unit, which has a function of keeping the recording head unit 38 in a printable state at all times. On the other hand, an ink cartridge 34 for ink of each color of cyan, magenta, yellow, and black is provided, and ink is supplied to the recording head unit 38 from four ink supply tanks 33. In the figure, 46
b indicates a drawing number reading means.

(Second embodiment) In this embodiment, as shown in FIG.
The inside diameter of “a” is about twice the inside diameter of the circulation pipe 32, and the other structure is the same as the structure of the first embodiment.

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

In both of the above embodiments, the present invention is applied to an ink jet recording apparatus having four ink supply tanks. However, the present invention is not limited to this, but may be applied to an ink jet recording apparatus having one ink supply tank. May be.

The present invention provides 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 sharp 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 corresponding 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.

It is preferable to add recovery means for the printhead, preliminary auxiliary means, and the like, which are provided as components of the printing apparatus of the present invention, since the effects of the present invention can be further stabilized. To be more specific, a capping unit, a cleaning unit, a pressure or suction unit, a preheating unit using an electrothermal converter, another heating element, or a combination thereof, for the recording head. 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 the printing mode of only the mainstream color such as black, but may be a printing head integrally formed or a combination of a plurality of printing heads. The present invention is extremely effective for an apparatus having at least one of the full colors.

[Effects of the Invention] Since the present invention is configured as described above, it is possible to provide an ink jet recording apparatus having the following effects.

At the time of recording, the amount of ink guided from the ink supply tank to the recording head through the first ink path can sufficiently compensate for the amount of ink ejected by the recording head, so that a full line type recording head consuming a large amount of ink In this case, the shortage of ink supply can be prevented, and the ink ejection response, ejection efficiency, and ejection stability do not decrease.
Further, when the recovery operation is performed, it is possible to form a good ink circulation flow without ink stagnation in the recording head,
Since excessive inflow of ink to the print head can be prevented,
Ink does not leak from the ink ejection port wastefully,
An ink jet recording apparatus without waste of ink can be provided.

[Brief description of the drawings]

FIG. 1 is a front view of an ink supply system and an ink recovery system of a first embodiment of an ink jet recording apparatus according to the present invention.
FIG. 3 is a schematic configuration diagram of a first embodiment, FIG. 3 is a front view of an ink supply system and an ink recovery system of a second embodiment of the present invention, and FIG.
FIG. 1 shows a conventional example, and is a configuration diagram of an ink supply system and an ink recovery system of an ink jet recording apparatus. 30 ... print 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: Recording head section, 39: Recovery cap section, 40: Belt transport section, 41: Tray, 42: Canner section, 43: Printer section, 44: ... Fixed paper discharge unit, 45a ... Paper cassette, 45b ... Conveying means, 46 ... Discharge means, 46a ... Document, 46b ... Drawing number reading means.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masatoshi Katai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yasushi Murayama 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Setsu Uchida, inventor 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Masaharu Nemura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yasuyuki Takanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-60-196351 (JP, A) JP-A-1-258958 (JP, A)

Claims (4)

(57) [Claims] An ink supply tank for storing ink to be supplied to the printhead, the ink supply tank being connected by a first ink path and a second ink path;
A pump is provided in the ink path. During recording, an ink supply flow from the ink supply tank to the recording head via the first ink path occurs in a non-operating state of the pump. During the recovery operation,
An ink jet recording apparatus, wherein the operation of the pump generates an ink circulating flow from the ink supply tank to the recording head via the second ink path and further to the ink supply tank via the first ink path. An ink jet recording apparatus, wherein a head of friction loss of the first ink path is smaller than a head of friction loss of the second ink path. 2. The ink jet recording apparatus according to claim 1, wherein the length of the first ink path is shorter than the length of the second ink path. 3. The ink jet recording apparatus according to claim 1, wherein an inner diameter of the first ink path is larger than an inner diameter of the second ink path. 4. The recording head according to claim 1, wherein said recording head is a full line type having ink discharge ports formed over the entire recording width of a recording material, and an electrothermal transducer for discharging ink using thermal energy. The inkjet recording apparatus according to claim 1, further comprising: