JP2002248782A - Ink jet recording device - Google Patents

Abstract

(57) [Problem] To prevent air from entering the ink supply path when replacing an ink tank or a recording head. SOLUTION: An ink supply unit 5 to which a main tank 4 is detachably attached and which has a shut-off valve 10 is provided.
Then, the carriage 2 on which the recording head 1 connected to the unit via the supply tube 6 is mounted is covered with the exterior 12 to which the tank cover 12a and the carriage cover 12e are attached. Replacement of main tank 4
Except for the replaceable state, the state is blocked by the tank cover 12a except for the state where the shut-off valve 10 is closed or the state where the recording operation is stopped. The recording head 1 is replaced according to the position of the carriage 2 except for a state where there is no ink in the supply tube 6 or a state where the shut-off valve 10 is closed, for example, except for a state where the recording head 1 can be replaced. Has been blocked by

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus configured to supply ink from a replaceable ink tank to a replaceable recording head through an ink supply path formed by a tube or the like.

[0002]

2. Description of the Related Art Among recording methods of printers and the like, an ink jet recording method of forming a character or an image on a recording medium by discharging ink from a discharge port (nozzle) to perform recording is a low-noise non-recording method. In recent years, since high-density and high-speed recording operation is possible by the impact recording method, it is widely used in recent years.

[0003] A general ink jet recording apparatus is provided with means for driving a carriage on which an ink jet recording head is mounted, conveying means for conveying a recording medium such as recording paper, and control means for controlling these. I have. Such a device that performs a printing operation while moving the carriage is called a serial type. On the other hand, a device that performs a recording operation only by transporting a recording medium without moving an inkjet recording head is called a line type. In the line type ink jet recording apparatus, the ink jet recording head has a number of nozzles arranged over the entire width of the recording medium in the width direction.

[0004] The ink jet recording head has an energy generating means for generating a discharge energy applied to the ink in the nozzle in order to discharge the ink droplet from the nozzle. As the energy generating means, one that presses ink using an electromechanical transducer element such as a piezo element, an electromagnetic wave mechanical transducer element that irradiates an electromagnetic wave such as a radio wave or a laser and converts the electromagnetic wave into mechanical vibration or heat, or There is a type using an electromagnetic wave heat conversion element, and a type using an electrothermal conversion element having a heating resistor or the like to heat and foam a liquid. Among them, the method of ejecting ink droplets by using thermal energy enables high-density recording because nozzles can be arranged at a high density. In particular, an ink jet recording head using an electrothermal transducer element as an energy generating element,
It is easier to miniaturize than the one using electromechanical transducer elements, and it makes full use of its advantages by applying IC technology and micro-machining technology, which have made remarkable advances in technology and reliability in recent semiconductor manufacturing fields. By doing so, there is an advantage that high-density mounting is easy and the manufacturing cost can be reduced.

As a method of supplying ink to the ink jet recording head, a so-called head tank integrated method in which an ink tank containing ink is integrated with the ink jet recording head, a so-called tube supply in which the ink tank and the ink jet recording head are connected by a tube. Method, and separately provide an ink tank and an ink jet recording head, move the ink jet recording head to the position of the ink tank as needed, connect them, and supply ink from the ink tank to the ink jet recording head during that time There is a so-called pit-in system.

If the capacity of the ink tank is increased in order to reduce the frequency of replacing the ink tank, the weight of the ink tank increases, so that in a serial type ink jet recording apparatus, the weight applied to the carriage increases. In consideration of this, a serial type ink jet recording apparatus using a large-capacity ink tank often employs a tube supply method or a pit-in method. In particular, in the pit-in system, it is necessary to stop the recording operation during the supply of ink, and thus a tube supply system capable of continuous recording for a long time is often used.

Hereinafter, an ink supply system of a tube supply type ink jet recording apparatus will be described with reference to FIG.

The ink supply system shown in FIG.
And a main tank 104 via a supply tube 106 serving as an ink supply path.
4 and a recording head 101 connected thereto.

The recording head 101 is of a type that discharges ink droplets by using thermal energy. The recording head 101 has a plurality of discharge nozzles 101g arranged to form an ink discharge section. The hole is formed. Each of the ejection nozzles 101g is arranged so that an opening surface (ejection port) thereof faces downward, and ink is ejected downward from each of the ejection nozzles 101g. Each discharge nozzle 101g has no particular valve mechanism.
By keeping the inside of g at a negative pressure, a meniscus of ink is stretched at the tip of the nozzle, thereby preventing ink leakage from the ejection nozzle 101g and entry of air from the atmosphere. The ink is ejected by extruding the ink from the ejection nozzle 101g by the film boiling energy of the heater arranged near the ejection nozzle 101g. After ejecting the ink,
A cycle in which the nozzle is filled with ink again by the capillary force of the discharge nozzle 101g is repeated, and the ink is sucked up from the main tank 104 via the supply tube 106 as needed.

[0010] Inside the recording head 101, a filter 101c having a fine mesh structure for preventing dust from being caught in a fine hole of the discharge nozzle 101g;
sub tank 101b for storing a fixed amount of ink upstream of c
And a narrow flow path 101f that connects the inside of the sub tank 101b to the discharge nozzle 101g via the filter 101c. The ink from the main tank 104 is supplied to the supply tube 106, the sub tank 101b, the filter 10
1c, and each discharge nozzle 101 through the flow path 101f.
g. In the middle of the supply tube 106, there is provided a valve 110a capable of switching its flow path between a shut-off state and a communication (open) state.
Driven by 0d. The supply tube 106 has a liquid connector 106a at the base of the recording head 101 side.
06 is detachable from the liquid connector 101a provided on the recording head 101, that is, the recording head 1
01 has a replaceable structure. Supply tube 10
One end of 6 communicates with the inside of the sub tank 101b by connecting the liquid connectors 106a and 101a. on the other hand,
The main tank 104 is formed of a flexible bag, and has a liquid connector 104a to which the other end (lower end) 105a of the supply tube 106 is connected. The other end 10 of the supply tube 106 is
The supply tube 106 communicates with the inside of the main tank 104 by detachably attaching 5 a to the main tank 104. Therefore, the main tank 104 can be exchanged for the ink jet recording apparatus.

A pressure adjusting chamber 101i is provided above the sub tank 101b by an elastic member 101h. The pressure adjustment chamber 101i stabilizes the pressure in the print head 101 by changing its volume in response to a change in the pressure in the sub tank 101b, and is mainly used when printing suddenly consumes ink during a printing operation. This is to alleviate a rise in pressure in the head 101.

In such an ink jet recording apparatus, when a thickened substance of the ink is clogged in the ejection nozzle 101g, or when air dissolved in the ink of the ejection nozzle 101g is accumulated to form bubbles. In general, a suction means 107 for sucking ink from each of the ejection nozzles 101g at a predetermined time to remove them is provided. The suction means 107 is provided with a suction cap 107 a that faces the opening surface (ejection port surface) of the nozzle of the recording head 101 and caps the opening surface, and a suction cap 107 a.
a and a suction pump 107c connected to the
7c, a driving means 107b such as a cam mechanism for bringing the suction cap 107a into or out of contact with the recording head 101, and a driving motor 107g for driving the suction cap 107a. The opening surface of the nozzle of the recording head 101 is set to the suction cap 107a.
The suction pump 107c is driven by the pump motor 107d in a state where the ink is capped, and the ink or air in the recording head 101 is forcibly sucked from each of the ejection nozzles 101g, so that the thickened ink and extra air bubbles of the ink are ejected from the ejection nozzle. Remove from 101 g.

In this ink jet recording apparatus, when the recording head 101 is initially filled with ink, or when the ink in the sub tank 101b decreases due to the accumulation of air in the sub tank 101b, the sub tank 101b is refilled with ink. For example, an operation of filling the recording head 101 with ink is performed.

In the ink filling operation, first, the discharge port surface of the recording head 101 is capped with a suction cap 107a, and with the valve 110a closed, ink or air is suctioned from a discharge nozzle 101g by a suction pump 107c. The pressure inside the sub tank 101b is reduced. When the pressure in the sub tank 101b reaches a predetermined pressure, the valve 110
Open a. Then, the depressurized sub tank 101b
The air inside contracts, and the ink from the main tank 104 is introduced into the sub tank 101b through the supply tube 106 and filled. Thereafter, when the suction cap 107a is separated from the recording head 101, the ink jet recording apparatus is ready for recording.

In the main tank 104, a rewritable nonvolatile memory element 104m for writing the amount of ink ejected from the main body of the ink jet recording apparatus as information and managing the remaining amount of ink in the main tank 104 is mounted. And the main tank 104 are detachably attached to the ink jet recording apparatus main body.

Although the conventional ink supply system has been described by taking the tube supply system as an example, the head-integrated system and the pit-in system also differ only in the structure relating to the ink supply path from the ink tank to the recording head. The structure below the filter of the recording head is basically the same as the tube supply system.

[0017]

However, in the conventional ink jet recording apparatus shown in FIG. 6, if the main tank 104 is detached from the apparatus main body while the ink is being ejected from the recording head 101 in the recording operation, the ink jet recording apparatus is not suitable. Is supplied to the recording head 101 at any time, so that there is a problem that air enters the supply tube 106 from the lower end of the supply tube 106 which is open to the atmosphere.
When air enters the supply tube 106 every time the main tank 104 is replaced, the amount of ink in the sub tank 101b decreases, and the print head 101 becomes in a state where printing is not possible. Further, when air enters the thin supply tube 106, a meniscus is formed at the boundary between ink and air in the tube, and the flow path resistance increases. Therefore, if the main tank 104 is removed during the printing operation, the above-described ink filling operation is executed every time the main tank 104 is replaced with safety. In the ink filling operation, the ink is consumed every time, so that the running cost of the ink increases, and the amount of the waste ink sucked increases, so that a large amount of waste ink tank is generated.

During the ink filling operation or when the supply tube 106
With the valve 110a in the middle of the opening, the suction cap 1
Even in a general suction operation in which the clogging of the ejection nozzle 101g is eliminated by sucking the ink through 07a, if the main tank 104 is pulled out during these operations, the same problem as described above occurs.

Even after the printing operation is completed, immediately after printing an image with a large amount of ink consumption, the pressure adjusting chamber 101
Since i has a small volume, the pressure adjustment chamber 101i may be trying to return to the original shape by sucking up ink from the main tank 104 into the sub tank 101b. In this case, when the main tank 104 is pulled out, air is drawn in from the lower end of the supply tube 106,
This causes the same problem as described above.

Further, when the recording head 101 is not connected to the supply tube 106,
When the recording head 101 and the main tank 104 are detached from the recording apparatus while the recording head 101 and the main tank 104 are attached to the recording apparatus, the main tank 1 is passed through the supply tube 106 from the upper end thereof.
Air is taken into 04. Thereafter, even if the recording head 101 is attached and the ink is filled into the recording head 101, the air in the main tank 104 sometimes enters the supply tube 106, causing the same problem as described above.

Recording head 101 and main tank 10
4 is normally attached to the recording apparatus main body, and the supply tube 10
When the recording head 6 is filled with ink and the recording head 101 is removed after the main tank 104 is removed and removed, the ink in the supply tube 106 leaks from the lower end thereof.

Further, if the main tank 104 is removed while information is being written to the memory element 104m attached to the main tank 104, the memory element 104m is also removed from the recording device together with the main tank 104. Therefore, there is a problem that the memory element 104m is broken.

An object of the present invention is to provide an ink jet recording apparatus configured to supply ink from a replaceable ink tank to a replaceable recording head through an ink supply path, when replacing an ink tank or a recording head.
Provided is an ink jet recording apparatus in which air does not enter the ink supply path in a state where a recording operation after replacement is possible and a memory attached to an ink tank is not destroyed when the tank tank is replaced. Is to do.

[0024]

In order to achieve the above object, the present invention is to supply ink contained in a replaceable ink tank to a recording head having ejection nozzles, and to supply the ink to the ink tank and the ejection tank. An ink supply path for applying a negative pressure to the ink in the discharge nozzles due to a difference in nozzle height, a valve provided in the ink supply path to open and close the path, An ink jet recording apparatus having only a suction means capable of sucking from the discharge nozzle is provided with a tank replacement preventing means for preventing the ink tank from being replaced except in a state where the ink tank can be replaced.

Further, according to the present invention, the ink contained in the ink tank is supplied to a replaceable recording head having a discharge nozzle, and the height difference between the ink tank and the discharge nozzle causes the ink in the discharge nozzle to be changed. An ink supply path for applying a negative pressure to the ink, a valve provided in the ink supply path to open and close the path, and suction means capable of suctioning the ink in the recording head from the discharge nozzle only at a predetermined time. In an inkjet recording apparatus having
The image forming apparatus further comprises a head replacement preventing unit for preventing the recording head from being replaced except when the recording head can be replaced.

Further, according to the present invention, the ink stored in the replaceable ink tank is supplied to a replaceable recording head having a discharge nozzle, and the height of the ink tank and the discharge nozzle is changed based on the height difference between the ink tank and the discharge nozzle. An ink supply path for applying a negative pressure to the ink in the ink cartridge, a valve provided in the ink supply path to open and close the ink supply path, and suction capable of sucking the ink in the recording head from the discharge nozzle only at a predetermined time. Means for preventing the ink tank from being replaced except when the ink tank is replaceable, and replacing the printhead except when the printhead is replaceable. And a head replacement preventing means for preventing the change.

The replaceable state of the ink tank includes, specifically, a state in which the valve is closed, a state in which the recording head is mounted on the ink jet recording apparatus, and a state in which the ink in the recording head is sucked by the suction means. Is a state in which the suction operation is stopped, and a state in which the discharge operation of the ink from the discharge nozzle is stopped.

The replaceable state of the recording head is, specifically, a state where there is no ink in the ink supply path or a state where the valve is closed.

Further, an ink chamber for storing the ink supplied from the ink tank is provided in the recording head, and the ink jet recording apparatus performs a suction operation by the suction means with the valve closed. It is preferable that the ink chamber has control means for filling the ink chamber with ink from the ink tank by opening the valve when the pressure in the ink chamber is reduced to a predetermined pressure.

Further, in the above-described ink jet recording apparatus, when the recording head and the ink tank are both detached, the inhibition of the exchange of the recording head by the head exchange preventing means is released, and the mounting of the recording head is performed. It is preferable that a control means is provided for preventing the exchange of the recording head by the head exchange preventing means and canceling the inhibition of the ink tank exchange by the tank exchange preventing means.

Further, the above-mentioned ink jet recording apparatus has control means for controlling the operation of the ink jet recording apparatus, and operation input means for inputting a signal for controlling the operation of the ink jet recording apparatus to the control means. Wherein the control means closes the valve in response to a signal from the operation input means and releases the ink exchange tank from being prevented from being replaced by the tank replacement preventing means, or a signal from the input means. It is preferable that the valve be closed in accordance with the input signal, and the prevention of the recording head from being replaced by the head replacement preventing means is released. Further, after the control means terminates the recording operation by the recording head in response to a signal from the operation input means, or after the recording operation is completed, the tank replacement preventing means controls the ink tank by the tank replacement inhibiting means. After the recording operation by the recording head is completed or after the recording operation is completed, the recording is stopped by the head replacement preventing unit in accordance with a signal from the exchange input or the signal from the operation input unit. It is preferable to release the inhibition of head replacement. Further, after the control means completes the suction operation of the ink in the recording head by the suction means in response to a signal from the operation input means, the tank replacement prevention means prevents the ink tank from being replaced. , Or in accordance with a signal from the operation input means, cancels the inhibition of the ink tank exchange by the tank exchange inhibition means, and releases the ink supply after the ink tank is removed from the ink supply path. Preferably, after the ink in the path is extracted by the suction operation of the suction unit, the prevention of the replacement of the recording head by the head replacement prevention unit is released.

Further, the ink jet recording apparatus may include:
A rewritable nonvolatile memory element mounted on the ink tank for managing the remaining amount of ink in the ink tank; and a memory provided on a recording apparatus main body on which the ink tank is replaceably mounted. A contact which comes into contact with an element, and a memory writing circuit provided in the recording apparatus main body and which writes the remaining amount of ink in the ink tank to the memory element as information, wherein the tank replacement preventing means comprises a memory writing circuit. It is preferable to prevent replacement of the ink tank during access to the memory element from the printer.

Further, the ink jet recording apparatus may include:
It is preferable that a driving unit for driving the suction unit be provided, and the tank replacement preventing unit be driven by the driving unit.

Further, the tank replacement preventing means has a cover member for covering the ink tank, and a lock means for locking the cover member so that the cover member is not opened when the cover member is closed, It is preferable that the ink jet recording apparatus has a release unit that releases the lock of the cover member by the lock unit when the ink tank is replaceable.

Further, the head replacement preventing means has a cover member for covering the recording head above the recording head when the carriage mounted with the recording head and moving moves to a predetermined position, Preferably, the recording head is allowed to be replaced by opening the cover member only when the recording head is stopped at the predetermined position.

In the invention as described above, the ink-jet recording apparatus is provided with the tank replacement preventing means for preventing the ink tank from being replaced except for the state where the ink tank can be replaced. For example, a state in which a valve provided in the ink supply path is closed,
The state where the ink ejection operation of the attached print head is stopped, the state where the suction operation of the ink in the print head by the suction unit is stopped, the state where the memory element attached to the ink tank is not accessed, and the like. In this case, by releasing the tank replacement prevention means, air does not enter the ink supply path when replacing the ink tank, and the memory element of the ink tank can be destroyed when replacing the tank tank. Disappears. In addition, since the ink jet printing apparatus is provided with a head replacement preventing unit for preventing the replacement of the print head except for the replaceable state of the print head, the replaceable state of the print head, for example,
In a state where there is no ink in the ink supply path or a state where the valve provided in the ink supply path is closed, the head replacement prevention means is released to enable a printing operation after the replacement of the print head. It is possible to replace the recording head so that air does not enter the ink supply path. When replacing the ink tank or the print head in a state other than those described above, the operation being performed is terminated, and then the tank replacement prevention means or the head replacement prevention means is released. Problems such as entry of air into the supply path can be reliably eliminated.

When newly installing both the recording head and the ink tank, in order to eliminate the above-mentioned problem, the operation of each exchange preventing means is controlled so that the recording head and the ink tank are mounted in this order. When removing the print head, first remove the ink tank, then suction and discharge the ink in the ink supply path by the suction means, and then remove each print prevention head so that the print head is removed. By controlling, the above problem is avoided.

For example, the head replacement preventing means enables the recording head to be replaced only when the carriage on which the recording head is mounted is stopped at a predetermined replacement position, and replaces the recording head at a position other than the replacement position. Can be used. Further, as the tank replacement preventing means, a means may be used in which a cover for covering the ink tank is provided above the ink tank, and the opening and closing of the cover is normally locked, and the lock is released at the time of replacement. The unlocking of the cover for the ink tank utilizes the driving of the suction means, thereby realizing a countermeasure against the above problem without increasing the cost of the recording apparatus.

[0039]

Next, embodiments of the present invention will be described with reference to the drawings.

Hereinafter, an ink jet supply system for supplying ink to an ink jet recording head via a tube in the ink jet recording apparatus of the present invention will be described with reference to FIGS.

FIG. 1 is a diagram for explaining the basic principle of ink supply in an ink jet recording apparatus according to one embodiment of the present invention. First, a general basic principle of ink supply in an ink jet recording apparatus will be described with reference to FIG.

As shown in FIG. 1, in the ink jet recording apparatus, the recording head 1 and the main tank 4 communicate with each other through a supply tube 6, and a flow path from the main tank 4 to each discharge nozzle 1g of the recording head 1 is formed. Filled with ink. The ejection nozzle 1g of the recording head 1 is disposed at a position higher than the liquid level of the ink contained in the main tank 4 by a height H, and the pressure in the recording head 1 is reduced to the negative pressure of the head difference of the height H. It is in a state of being kept. A fixed amount of ink 9 is stored in the recording head 1.

In the ink jet recording system, the discharge nozzle 1g of the recording head 1 is a fine hole, and the discharge nozzle 1g has no particular valve mechanism. By maintaining the inside of the discharge nozzle 1g at a negative pressure, a meniscus of ink is stretched at the tip of the nozzle, thereby preventing ink leakage from the discharge nozzle 1g and entry of air from the atmosphere into the discharge nozzle 1g. . The ink is ejected by extruding the ink in the ejection nozzle 1g by the film boiling energy of a heater (not shown) arranged near the ejection nozzle 1g. After the discharge of the ink, a cycle of filling the ink in the nozzle again by the capillary force of the discharge nozzle 1g is repeated, and the ink is sucked up again from the main tank 4 to the recording head 1 through the supply tube 6.

The ink jet recording apparatus described in the present embodiment is based on the above-described principle, and further has another configuration.

FIG. 2 is a perspective view showing a schematic configuration of an ink jet recording apparatus according to one embodiment of the present invention.

In the ink jet recording apparatus shown in FIG. 1, a reciprocating movement (main scanning) of the recording head 1 in the main scanning direction and sub-scanning of a recording sheet S such as general recording paper, special paper, OHP film, etc. at a predetermined pitch are performed. The ink is selectively ejected from the recording head 1 and attached to the recording sheet S while synchronizing with these movements while repeating conveyance (sub-scanning) in the direction, thereby forming characters, symbols, images, and the like. This is a serial type recording device.

In FIG. 1, a recording head 1 is detachably mounted on a carriage 2 slidably supported by two guide rails and reciprocated along the guide rails by driving means such as a motor (not shown). It is installed in. The recording sheet S faces the ink ejection surface of the recording head 1 by the transport roller 3 and intersects with the moving direction of the carriage 2 so as to maintain a constant distance from the ink ejection surface (for example, It is transported in the direction of arrow A which is a direction orthogonal to the direction.

The recording head 1 has a plurality of nozzle rows for ejecting inks of different colors. Each of these nozzle arrays extends in a direction substantially orthogonal to the main scanning direction of the recording head 1. A plurality of independent main tanks 4 correspond to the colors of ink ejected from the recording head 1.
The ink supply unit 5 is detachably mounted, that is, exchangeable. The ink supply unit 5 and the recording head 1
By connecting the main tank 4 to the ink supply unit 5 by connecting a plurality of supply tubes 6 corresponding to the colors of the inks, ink of each color stored in the main tank 4 is supplied to each nozzle row of the recording head 1. Can be supplied independently. The main tank 4, the ink supply unit 5, and the supply tube 6 constitute an ink supply path for supplying ink to the recording head 1.

Within the reciprocating range of the recording head 1 and
In a non-recording area, which is an area outside the passing range of the recording sheet S, a recovery unit 7 adjacent to the ink supply unit 5
Are arranged so as to face the ink ejection surface of the recording head 1. The recovery unit 7 is a mechanism for forcibly sucking ink or air in each of the discharge nozzles 1g of the recording head 1 from an opening end thereof, and cleaning the discharge nozzles 1g and filling the recording head 1 with ink, which will be described later. It is.

Next, a detailed configuration of the ink supply system of the ink jet recording apparatus will be described with reference to FIG. FIG. 3 is a sectional view of the inkjet recording apparatus shown in FIG.
FIG. 4 is a diagram for explaining an ink supply path for a color component. FIG. 4 is a view for explaining the behavior of air and ink in the liquid path of the ink supply unit when air is introduced into the main tank in the ink supply path shown in FIG. FIG. 5 is a diagram illustrating the pressure due to the head difference applied to the nozzles in the ink supply path shown in FIG.

First, the recording head 1 will be described.

An electric board 1j is attached to a side surface of the recording head 1. When the recording head 1 is mounted on the carriage 2, the electric board 1 j connects to a contact 2 a provided on the carriage 2. A plurality of terminals such as a terminal for supplying power from the printing apparatus main body and a terminal for exchanging signals between the printing apparatus main body and the recording head 1 are formed on the electric board 1j. Some of these terminals have two terminals short-circuited. On the recording apparatus main body side, if the contact 2a corresponding to those terminals is open,
It is determined that there is no head in a state where the recording head 1 is not mounted. If the head is closed, it is determined that there is a head in a state where the recording head 1 is mounted on the carriage 2. If it is determined that there is a head, then power is supplied to the recording head 1 and the recording apparatus main body and the recording head 1
Start signal exchange with

The recording head 1 is supplied with ink from a connector insertion port 1a to which a liquid connector provided at the tip of a supply tube 6 is detachably and air-tightly connected. The connector insertion opening 1a communicates with a sub-tank 1b formed as an ink chamber above the recording head 1 and storing a predetermined amount of ink. A liquid chamber 1f for directly supplying ink to a nozzle portion having a plurality of discharge nozzles 1g arranged in parallel is formed below the sub-tank portion 1b in the direction of gravity. The sub-tank 1b and the liquid chamber 1f are partitioned by a filter 1c. The filter 1c has a partition 1e having an opening 1d at the boundary between the sub-tank 1b and the liquid chamber 1f. 1e.

In the ink passage inside the recording head 1, the ink supplied to the recording head 1 from the connector insertion opening 1 a is supplied to the sub tank 1 by the above-described configuration.
b, the filter 1c, and the liquid chamber 1f, and are supplied to each discharge nozzle 1g. The space from the connector insertion opening 1a to the discharge nozzle 1g is kept airtight with respect to the atmosphere.

An opening is formed in the upper surface of the sub tank portion 1b, and the opening is covered with a dome-shaped elastic member 1h fixed to the upper surface of the recording head 1. The space (pressure adjustment chamber 1i) surrounded by the elastic member 1h communicates with the inside of the sub-tank section 1b through the opening, and the volume changes according to the pressure in the sub-tank section 1b. In this way, it has a function of adjusting the pressure in the sub tank portion 1b.

The discharge nozzle 1g has a fine cylindrical structure with a cross section width of about 20 μm, and discharges ink by applying discharge energy to the ink in the discharge nozzle 1g.
g, and after the ink is discharged, the ink is filled in the discharge nozzle 1g by the capillary force of the discharge nozzle 1g. Normally, this ejection is repeated at a cycle of 20 kHz or more, and fine and high-speed image formation is performed. Discharge nozzle 1
In order to give ejection energy to the ink in g, the recording head 1 has an energy generating means for each ejection nozzle 1g. In the present embodiment, as the energy generating means,
A heating resistor element for heating the ink in the ejection nozzle 1g is used, and the heating resistor element is selectively driven by a command from a head control unit (not shown) for controlling the driving of the recording head 1, and a desired ejection nozzle is provided. 1 g of the ink is boiled,
Discharge nozzle 1g using pressure of bubble generated by this
Is ejected from the printer.

As described above, the ejection nozzles 1g are arranged with the tip for ejecting ink facing downward, but there is no valve mechanism for closing the tip, and the ink is discharged in a state where a meniscus is formed. It satisfies the discharge nozzle 1g. Therefore, the inside of the recording head 1, especially the inside of the ejection nozzle 1g, is kept in a negative pressure state. However, if the negative pressure is too small, when foreign matter or ink adheres to the tip of the ejection nozzle 1g, the meniscus of the ink may collapse and the ink may leak from the ejection nozzle 1g. On the other hand, if the negative pressure is too large, the force of pulling the ink back into the ejection nozzle 1g becomes stronger than the energy given to the ink at the time of ejection, resulting in ejection failure. Therefore, the negative pressure in the discharge nozzle 1g is kept in a certain range slightly lower than the atmospheric pressure. The range of the negative pressure varies depending on the number of the nozzles 1g, the sectional area, the performance of the heating resistance element, and the like. However, according to the experimental results of the present inventors, -40 mm
Aq (about -0.0040 atm = -4.053 kPa)
~ -200 mmAq (about -0.0200 atm = -2.
0265 kPa) (however, the specific gravity of the ink / the specific gravity of water) is preferable.

The filter 1c is for preventing foreign matter that may clog the discharge nozzle 1g from flowing out of the sub tank portion 1b to the liquid chamber 1f.
And a metal mesh having fine pores of 10 μm or less smaller than the cross-sectional width of. The filter 1c is a filter 1
When the ink comes into contact with only one surface of c, a meniscus of the ink is formed in each of the fine holes due to the capillary force, and the ink easily permeates but the air flow is difficult. The smaller the size of the micropores, the higher the strength of the meniscus and the more difficult it is to pass air.

In the filter 1c used in the present embodiment, the pressure required to transmit air is 0.1 atm.
(10.1325 kPa) (experimental value). Therefore, if air exists in the liquid chamber 1f located downstream of the filter 1c with respect to the direction of movement of the ink in the recording head 1, the air cannot pass through the filter 1c with the buoyancy of the air itself. The air inside is the liquid chamber 1f
Stay within. In the present embodiment, this phenomenon is utilized, and the liquid chamber 1f is not filled with ink, and an air layer exists between the ink in the liquid chamber 1f and the filter 1c. A predetermined amount of ink is stored in the liquid chamber 1f so as to separate the ink from the filter 1c.

The amount of ink stored in the liquid chamber 1f is at least the amount required to fill the discharge nozzle 1g with ink. When the air from the liquid chamber 1f enters the discharge nozzle 1g, the ink is not replenished to the discharge nozzle 1g after the ink is discharged, and a discharge failure occurs. Therefore, the discharge nozzle is provided below the liquid chamber 1f for storing a certain amount or more of ink. Place 1g downward,
The inside of the discharge nozzle 1g must always be filled with ink so that air does not enter the discharge nozzle 1g.

On the upper surface of the filter 1c, a sub tank 1b is provided.
The area in contact with the ink is the effective area of the filter 1c. Filter 1c
Is dependent on the effective area of the filter 1c. The area of the filter 1c is set so that the pressure loss is equal to or less than an allowable value. The pressure loss increases as the mesh of the filter 1c becomes finer and the flow rate of ink increases. Conversely, it is inversely proportional to the area of the filter 1c. In recent high-speed, multi-nozzle, small dot printers, the pressure loss tends to be high, and the size of the filter is 10 × 20 m.
m, which requires a sub-tank section upstream of the filter and a liquid chamber space downstream. In the present embodiment, the filter 1c is arranged so as to be horizontal when the recording head 1 is used, and the ink is brought into contact with the entire upper surface of the filter 1c to maximize the effective area of the filter and reduce the pressure loss. .

The pressure adjustment chamber 1i is a chamber whose volume decreases as the internal negative pressure increases, and
When this is constituted by the elastic member 1h as in the present embodiment, a rubber material or the like is preferably used as the elastic member 1h. Moreover, you may comprise with the combination of a plastic sheet and a spring other than the elastic member 1h. The volume of the pressure adjustment chamber 1i is set according to the environmental temperature at which the recording head 1 is used, the volume of the sub tank 1b, and the like.
In this embodiment, the volume is about 0.5 ml.

When the pressure adjusting chamber 1i is not provided, the pressure in the sub tank portion 1b is directly affected by the resistance due to the pressure loss when the ink passes through the main tank 4, the ink supply unit 5, and the supply tube 6. Therefore, in the case of a so-called high duty in which ink is ejected at a high rate, such as ejecting ink from all the ejection nozzles 1g, the pressure in the sub tank portion 1b is controlled by the supply tube 6, the ink supply unit 5, and the main tank 4. Since the ink is subjected to resistance due to pressure loss when passing therethrough, the amount of ink supplied to the recording head 1 becomes insufficient with respect to the ejected ink, and the negative pressure rapidly increases. The negative pressure of the discharge nozzle 1g is -200 mmAq (about-
If the pressure exceeds 2.0265 kPa), the ejection becomes unstable, which is inconvenient for image formation.

In the serial type recording apparatus as in the present embodiment, there is a state in which after forming an image with a high duty, the ejection of ink is interrupted when the carriage 2 (see FIG. 2) is reversed. I do. In this case, the pressure adjustment chamber 1
i plays a role of a capacitor, such as reducing the volume during ejection of ink to mitigate a rise in negative pressure in the sub-tank portion 1b and restoring the ink at the time of inversion.

For example, the rate of change of the negative pressure with respect to the reduction of the volume of the pressure adjusting chamber 1i is expressed as K = −1.01325 kPa /
Assuming that the volume of the sub tank 1b is V _s = 2 ml, the supplied ink is ΔV
= Consider the case of 0.05 ml shortage. In this case, if there is no pressure adjustment chamber 1i, the principle of "PV = constant"
The change in the negative pressure in the sub tank portion 1b is ΔP = V _s / (V _s +
ΔV) -1 = −2.270 kPa, which exceeds the above-mentioned limit value, so that the ejection becomes unstable. On the other hand, if there is a pressure adjustment chamber 1i, ΔP = K × ΔV = −0.
507 kPa, and a rise in negative pressure is suppressed, so that stable ejection can be performed.

As described above, the pressure adjustment chamber 1 i stabilizes the ejection of the ink and suppresses the influence of the pressure loss in the ink supply path from the main tank 4 to the recording head 1. For this reason, the supply tube 6 driven by the carriage 2 can also be used with a small diameter, which contributes to a reduction in the load of movement of the carriage 2.

Next, the ink supply unit 5 and the main tank 4 will be described. The main tank 4 is detachable from the ink supply unit 5, and has two rubber stoppers 4b under the rigid case 4a. 4c is attached. The main tank 4 is a sealed container by itself, and the ink 9 is stored in the main tank 4 in a liquid state.

On the other hand, the ink supply unit 5 has an ink supply needle 5a for taking out the ink 9 from the main tank 4.
And an air introduction needle 5b for introducing air into the main tank 4. The ink supply needle 5a and the air introduction needle 5b are both hollow needles, and are arranged with their needles facing upward corresponding to the positions of the ink supply port and the air introduction port of the main tank 4. By being attached to the ink supply unit 5, the ink supply needle 5a and the air introduction needle 5b penetrate the rubber stoppers 4b and 4c, respectively, and enter the inside of the main tank 4. Thereby, the flow path in the main tank 4 and the flow paths in each needle can be communicated.

The ink supply needle 5a is connected to the supply tube 6 via a path of a liquid path 5c, a selectively openable / closable shutoff valve 10, and a liquid path 5d, and further communicates with the recording head 1. The air introduction needle 5b is connected to the liquid path 5e, the buffer chamber 5
f, It communicates with the atmosphere through the air communication port 5g. A liquid path 5c at the lowest position in the ink supply path from the ink supply needle 5a to the supply tube 6, and an air introduction needle 5b.
And the liquid path 5e at the lowest position in the path from the path to the air communication port 5g is the same height. In the present embodiment, the ink supply needle 5a and the air introduction needle 5b are:
In order to suppress the flow resistance of the ink, a thick one having an inner diameter of 1.6 mm is used.
5 mm.

The shutoff valve 10 has a diaphragm 10a made of a rubber material, and opens and closes the two liquid paths 5c and 5d by vertically displacing the diaphragm 10a. On the upper surface of the diaphragm 10a, a cylindrical spring holder 10b holding a pressing spring 10c inside is attached, and the pressing spring 10c causes the diaphragm 10a.
When the opening of the liquid passage 5d is closed by the lower surface of the diaphragm 10a by pressing the central portion of the diaphragm 10a to crush the diaphragm 10a, the liquid passages 5c and 5d are shut off.
The spring holder 10b has a flange with which a lever 10d operated by a link 7e of the recovery unit 7 described later engages. By operating the lever 10d, the pressing spring 10c
By lifting the spring holder 10b against the spring force, the liquid paths 5c and 5d communicate with each other. The shut-off valve 10 is opened when the recording head 1 is ejecting ink, closed during standby and pause, and is opened and closed at the same time as the recovery unit 7 during an ink filling operation described later.

The structure of the above-described ink supply unit 5 is as follows.
Except for the lever 10d, it is provided for each main tank 4, that is, for each ink of black, cyan, magenta, and yellow. The lever 10d is common to all colors, and simultaneously opens and closes the shutoff valves 10 for all colors. That is, there is one lever 10d, and the spring holder 1 of the shutoff valve 10 of each color is provided at the point of action of the lever 10d.
0b, and all the shut-off valves 10 are simultaneously opened and closed by one lever 10d.

With the above configuration, when the ink in the recording head 1 is consumed, the ink is supplied from the main tank 4 to the recording head 1 via the ink supply unit 5 and the supply tube 6 as needed due to the negative pressure. You. At this time, the same amount of air as the ink supplied from the main tank 4 is introduced into the main tank 4 through the air communication port 5g, the buffer chamber 5f, and the air introduction needle 5b.

The buffer chamber 5f is a space for temporarily holding ink flowing out of the main tank 4 due to expansion of air in the main tank 4, and the lower end of the air introduction needle 5b is located at the bottom of the buffer chamber 5f. are doing. When the air in the main tank 4 expands, for example, when the ambient temperature rises or the outside air pressure drops while the inkjet recording apparatus is on standby or stopped, the shut-off valve 10 is closed. The ink flows from the air introduction needle 5b to the buffer chamber 5f via the liquid path 5e. Conversely, when the air in the main tank 4 contracts due to, for example, a decrease in the environmental temperature, the ink flowing out into the buffer chamber 5f is removed from the main tank 4.
Return to When ink is ejected from the recording head 1 while ink is present in the buffer chamber 5f, first,
After the ink in the buffer chamber 5f returns to the main tank 4 and the ink in the buffer chamber 5f runs out, air is introduced into the main tank 4.

The volume _Vb of the buffer chamber 5f is set so as to satisfy the use environment of the product. For example, 5 ° C. (278
K) If the product is intended for use within the temperature range of 35 ° C. (308 K), the capacity of the main tank 4 is set to 100 m.
Assuming l, V _b = 100 × (308-278) / 30
8 = 9.7 ml or more.

Here, the basic head of the main tank 4 and the behavior of air and ink in the liquid path of the ink supply unit 5 when air is introduced into the main tank 4 will be described.
This will be described with reference to FIG.

FIG. 4A shows a normal state in which ink can be supplied from the main tank 4 to the recording head 1 (see FIG. 3). In this state, since the inside of the main tank 4 is airtight except for the buffer chamber 5f, the inside of the main tank 4 is maintained at a negative pressure, and the leading end 9a of the ink remains in the middle of the liquid passage 5e. The pressure at the tip 9a of the ink is atmospheric pressure (= 0 mmAq) because it is in contact with the atmosphere. Liquid path 5e where ink tip 9a is located and supply tube 6 (see FIG. 3)
Is the same height as the fluid path 5c communicating with the
Since the space between 5e is communicated only with the ink, the pressure in the liquid passage 5c also becomes the atmospheric pressure. This is the ink tip 9a and the liquid path 5
The height of the main tank 4
It is not affected by the amount of the ink 9 inside.

When the ink in the main tank 4 is consumed, as shown in FIG. 4B, the leading end 9a of the ink gradually moves toward the air introduction needle 5b and reaches just below the air introduction needle 5b. At this point, as shown in FIG. 4 (c), the air bubbles float in the air introduction needle 5 b and are introduced into the main tank 4. Instead, the ink in the main tank 4 enters the air introduction needle 5b, and the leading end 9a of the ink returns to the original state shown in FIG.

FIG. 4D shows a state where ink is accumulated in the buffer chamber 5f. In this case, the leading end 9a of the ink is h1 higher than the liquid path 5c, which is located in the middle of the buffer chamber 5f in the height direction.
(Mm), and the pressure in the liquid passage 5c is -h1 (mmAq).

As described above, in this embodiment, the pressure due to the head difference applied to the discharge nozzle 1g (see FIG. 3) is as shown in FIG.
The height from the liquid path 5c to the ink upper surface 9b in the sub tank portion 1b is h2 (mm), and the height from the filter 1c to the ink upper surface 9b in the sub tank portion 1b is h3.
(Mm), and the height from the lower end of the discharge nozzle 1g to the ink top surface 9c of the liquid chamber 1f and h4 (mm), the negative pressure P _n of the discharge nozzle 1g lower end, in the normal state, P _n ≒ −
9.8 × (h2−h3−h4) Pa, and _Pn ≒ −9.8 × Pa in a state where ink is accumulated in the buffer chamber 5f.
(H2-h1-h3-h4) Pa. The value of P _n is
The aforementioned negative pressure range (−4.053 kPa to −2.02)
65 kPa).

The main tank 4 has a rewritable nonvolatile memory element 4m mounted thereon. Memory element 4m
Is used to manage the remaining amount of ink in the main tank 4, and the amount of ink consumed in the ink jet recording apparatus is written into the memory element 4m as needed. A contact 5h is provided on the ink supply unit 5, that is, the recording apparatus main body, and the memory element 4m contacts the contact 5h on the recording apparatus main body side with the main tank 4 mounted on the ink supply unit 5. When the main tank 4 is detached from the ink supply unit 5, the memory element 4m is also detached from the contact 5h. Among the plurality of terminals provided in the memory element 4m, there are those in which two terminals are short-circuited. On the recording apparatus main body side, if the contact 5h corresponding to those terminals is open, the main tank 4 is in ink. Supply unit 5
It is determined that there is no tank in which the main tank 4 is not attached to the ink supply unit 5 if the tank is closed. Further, the main body of the recording apparatus is provided with a memory writing circuit for writing information such as the remaining amount of ink in the main tank 4 into the memory element 4m.

Next, the recovery unit 7 will be described.

The recovery unit 7 sucks ink and air from the discharge nozzle 1g and opens and closes the shutoff valve 10, and caps the ink discharge surface of the recording head 1 (the surface where the discharge nozzle 1g is open). A suction cap 7a,
And a link 7e for operating the lever 10d of the shutoff valve 10. The suction cap 7a, the suction pump 7c, the pump motor 7d, and the like constitute a suction unit that suctions the ink in the recording head 1 from the discharge nozzle 1g only at a predetermined time.

The suction cap 7a has at least a portion in contact with the ink ejection surface made of an elastic member such as rubber, and is provided movably between a position for sealing the ink ejection surface and a position retracted from the recording head 1. ing. A tube having a tube pump type suction pump 7c having a plurality of rollers at an intermediate portion is connected to the suction cap 7a, and continuous suction is possible by driving the suction pump 7c by a pump motor 7d. Further, the suction amount can be changed according to the rotation amount of the pump motor 7d. In the present embodiment, 0.4 atm (40.53 kP
The suction pump 7c capable of reducing the pressure up to a) is used.

The cam 7b operates by moving the suction cap 7a up and down between the above two positions. The cam 7b is rotated by a cam control motor 7g as driving means in synchronization with a cam 7f for operating the link 7e. You. Link 7e
Moves the lever 10d by sliding with the cam 7f, thereby opening and closing the shutoff valve 10. The power of the cam control motor 7g is transmitted to the cam 7b via the pendulum gear 7h.
And 7f. Pendulum gear 7h
Is supported so that it can swing between a gear 7m for rotating the cams 7b and 7f and a gear 7n for rotating the unlocking cam 7j so as to control the operation of the cover lock 11 as described later. Have been. Cam control motor 7
g, the pendulum gear 7h swings to the gear 7m side and meshes with the gear 7m, so that the cam control motor 7g
Is transmitted to the cams 7b and 7f. On the other hand, in the reverse drive of the cam control motor 7g, the pendulum gear 7
The power of the cam control motor 7g is transmitted to the lock release cam 7j by the h swinging toward the gear 7n and meshing therewith.

The timing at which the positions a to c of the cam 7b come into contact with the suction cap 7a are determined by the timings a to c of the cam 7f.
At the timing of contact with the link 7e. In the position a, the cam 7b is
a from the ink discharge surface of the recording head 1 and the cam 7
f pushes the link 7e to push up the lever 10d,
The shutoff valve 10 is opened. In the position b, the cam 7b brings the suction cap 7a into close contact with the ink ejection surface, and the cam 7f pulls back the link 7e to close the shutoff valve. At the position c, the cam 7b brings the suction cap 7a into close contact with the ink ejection surface, and the cam 7f presses the link 7e to open the shut-off valve 10.

At the time of the recording operation, the cams 7b and 7f are set at the position a, the suction cap 7a is separated from the ink discharge surface, the shut-off valve 10 is opened, the ink is discharged from the discharge nozzle 1g, and the main tank 4 is discharged. To supply ink to the recording head 1. During non-operation including standby and rest, the cams 7b and 7f are set to the position b, the ink ejection surface is covered by the suction cap 7a to prevent the ejection nozzle 1g from drying, and the shutoff valve 10 is closed to close the recording head. 1 to prevent the ink from flowing out (especially when the device itself moves, the device may be tilted and the ink may flow out). The position of c of the cams 7b and 7f will be described below.
It is used when the recording head 1 is filled with ink.

On the other hand, when the cam control motor 7g is driven in the reverse direction, the pendulum gear 7h swings and meshes with the gear 7n,
The unlocking cam 7j is rotated via those gears. During one rotation of the lock release cam 7j, the cover lock 11 is slid one reciprocation so as to release the lock of the tank cover 12a by the cover lock 11 as described later. Therefore, the unlocking cam 7j
Is a release means for releasing the lock of the tank cover 12a by the cover lock 11, and the release of the lock of the tank cover 12a is driven by a cam control motor 7g which is a drive means of the recovery unit 7.

The ink supply path from the main tank 4 to the recording head 1 has been described above. However, in the configuration shown in FIG. 2, air is accumulated in the recording head 1 over a long period of time.

In the sub-tank portion 1b, air penetrating through the supply tube 6 and the elastic member 1h, and air dissolved in the ink are accumulated. As for the air passing through the supply tube 6 and the elastic member 1h, a material having a high gas barrier property may be used as a constituent material thereof, but a material having a high gas barrier property is expensive and mass-produced consumer equipment. In this case, a high-performance material cannot be easily used due to cost reasons. In this embodiment,
The supply tube 6 is a low-cost, highly flexible and easy-to-use polyethylene tube, and the elastic member 1h is made of butyl rubber.

On the other hand, in the liquid chamber 1f, the discharge nozzle 1
When the ink is ejected from the ink g, bubbles generated by the film boiling of the ink break up and return to the liquid chamber 1f, or fine bubbles dissolved in the ink gather due to a rise in the temperature of the ink in the ejection nozzle 1g. The air gradually accumulates due to the large bubbles. According to experiments performed by the inventors,
In the configuration shown in the present embodiment, the sub tank portion 1b
The amount of accumulated air in the chamber is about 1 ml per month,
The amount of air accumulated in the chamber was about 0.5 ml per month.

If the accumulated amount of air in the sub tank 1b and the liquid chamber 1f is large, the sub tank 1b and the liquid
The amount of ink stored in each of f decreases. In the sub-tank portion 1b, when the ink is insufficient, the filter 1c is exposed to the air and the effective area of the filter 1c decreases, and as a result, the pressure loss of the filter 1c increases,
In the worst case, ink cannot be supplied to the liquid chamber 1f. On the other hand, in the liquid chamber 1f, when the upper end of the discharge nozzle 1g is exposed to air, ink supply to the discharge nozzle 1g becomes impossible. As described above, a critical problem arises when neither the sub-tank portion 1b nor the liquid chamber 1f contains a certain amount of ink.

Accordingly, the sub-tank unit 1 is provided at predetermined intervals.
By filling each of b and the liquid chamber 1f with an appropriate amount of ink, the ink discharge function can be stably maintained for a long period of time without using a material having high gas barrier properties. For example, in the case of the present embodiment, the sub-tank portion 1b and the liquid chamber 1f may be filled with the amount of air accumulated per month plus the variation at the time of filling each month.

The sub tank 1b and the liquid chamber 1f are filled with ink by using the suction operation of the recovery unit 7. That is, the suction pump 7c is driven while the ink ejection surface of the recording head 1 is sealed with the suction cap 7a,
This is performed by sucking the ink in the recording head 1 from the ejection nozzle 1g. However, if the ink is simply sucked from the discharge nozzle 1g, substantially the same amount of ink as the ink sucked from the discharge nozzle 1g flows into the liquid chamber 1f from the sub-tank portion 1b, and similarly to the ink flowing out from the sub-tank portion 1b. Only the same amount of ink flows from the main tank 4 to the sub tank portion 1b, and the situation is almost the same as before suction.

Therefore, in this embodiment, the filter 1
In order to fill each of the sub-tank portion 1b and the liquid chamber 1f partitioned by c with an appropriate amount of ink, the pressure in the sub-tank portion 1b and the liquid chamber 1f is reduced to a predetermined pressure by using the shut-off valve 10.

The operation of filling the sub tank 1b and the liquid chamber 1f with ink will be described below.

In the ink filling operation, first, the carriage 2 (see FIG. 2) is moved to a position where the recording head 1 faces the suction cap 7a, and the cam control motor 7g of the recovery unit 7 is driven to rotate in the normal direction to drive the cams 7b and 7b. 7f is rotated until the position of b contacts the suction cap 7a and the link 7e, respectively. As a result, the ink ejection surface of the recording head 1 is sealed by the suction cap 7a, and the shutoff valve 10 is in a state where the ink supply path from the main tank 4 to the recording head 1 is closed.

In this state, the pump motor 7d is driven, and suction is performed from the suction cap 7a by the suction pump 7c.
By this suction, the ink and air remaining in the print head 1 are sucked through the discharge nozzle 1g, and the pressure inside the print head 1 is reduced. When the amount of suction by the suction pump 7c reaches a predetermined amount, the suction pump 7c is stopped,
The cam control motor 7g is driven to rotate the cams 7b and 7f until the position of c contacts the suction cap 7a and the link 7e. Thereby, the shut-off valve 10 is kept in a state where the ink ejection surface is closed by the suction cap 7a.
Is opened. The suction amount by the suction pump 7c is a suction amount at which the pressure in the recording head 1 becomes a predetermined pressure necessary for filling the sub-tank portion 1b and the liquid chamber 1f with an appropriate amount of ink. Etc.

When the shutoff valve 10 is opened, the ink flows into the depressurized recording head 1 via the supply tube 6, and the sub tank 1b and the liquid chamber 1f are filled with the ink. The amount of ink to be filled is a volume required for the depressurized sub-tank portion 1b and the liquid chamber 1f to return to substantially atmospheric pressure.
It is determined by the volume and pressure of f.

The filling of the ink into the sub tank 1b and the liquid chamber 1f is completed in about one second after the shut-off valve 10 is opened. When the ink filling is completed, the cam control motor 7
g is rotated forward to rotate the cams 7b and 7f to positions where the position of a contacts the suction cap 7a and the link 7e, respectively. Thereby, the suction cap 7a is separated from the recording head 1, and the suction pump 7c is driven again to suck the ink remaining in the suction cap 7a. In this state, the shut-off valve 10 is in the open state, so that the discharge nozzle 1
g, and a state in which characters, images, and the like can be formed on the recording sheet S (see FIG. 2) by ink ejection is obtained. During standby and rest, the cam control motor 7g is driven again to move the cams 7b and 7f to the respective positions of the suction cap 7b.
Then, the print head 1 is rotated to a position where it comes into contact with the link 7e and the link 7e.

Next, the exterior of the ink jet recording apparatus will be described.

The exterior 12 of the ink jet recording apparatus surrounds the entire apparatus main body and protects the mechanism inside the apparatus.
A tank cover 12a that covers the main tank 4 is provided on the top surface of the exterior 12 so as to be rotatable around its end. A lock claw 12c is provided to lock the lock 12a. A lock claw 11c with which a lock claw 12c is engaged is provided at a distal end portion of the cover lock 11 opposite to the lock release cam 7j. When the lock claws 11c and 12c are engaged, the tank cover 12a is locked by the cover lock 11 so that the tank cover 12a is not opened when it is closed.

[0102] The tank cover 12a is
Slides, the lock claw 12c is disengaged from the lock claw 11c and is opened by the elastic force of the spring 12d. When the tank cover 12a is opened, the main tank 4 can be attached and detached. After the attachment and detachment of the main tank 4 is completed, the tank cover 12a
Is manually closed, the lock claws 12c are caught by the lock claws 11c of the cover lock 11, so that the tank cover 12a cannot be opened. Therefore, the tank cover 12a is a tank replacement preventing unit that prevents the main tank 4 from being replaced, that is, to be detached and attached by closing the tank cover 12 at an arbitrary time. The tank cover 12a prevents the replacement of the main tank 4 except for the replaceable state of the main tank 4, and the replaceable state of the main tank 4 includes a state in which the shut-off valve 10 is closed and A state in which the recording head 1 is mounted on the ink jet recording apparatus, a state in which the ink suction operation in the recording head 1 by the recovery unit 7 is stopped, and a state in which the ink discharging operation from the discharge nozzle 1g is stopped. It is. Inside the exterior 12, there is a cover sensor 13 for detecting the open or closed state of the tank cover 12a. Based on the detection signal from the cover sensor 13, the control circuit of the recording apparatus monitors the open / close state of the tank cover 12a. are doing.

The exterior 12 has a head replacement hole 12f located above the carriage 2 when the carriage 2 moves to a specific position in the main scanning direction. The specific position of the carriage is an exchange position for exchanging the recording head 1 on the carriage 2 through the head exchange hole 12f. A carriage cover 12e for covering the head replacement hole 12f is attached to the exterior 12 so as to be rotatable around its end. The operation of attaching and detaching the recording head 1 to and from the carriage 2 such as exchanging the recording head 1 can be performed only when the carriage 2 is directly below the head exchange hole 12f. The exterior 12, the carriage cover 12e, the carriage 2, and the like constitute a head replacement prevention unit that prevents the recording head 1 from being replaced, that is, removed, except in a state where the recording head 1 can be replaced. The head replacement preventing means allows the recording head 1 to be replaced by opening the carriage cover 12e only when the carriage 2 is stopped at the predetermined replacement position. The replaceable state of the recording head 1 is, specifically, the main tank 4
This is a state where there is no ink in the ink supply path from to the recording head 1 and a state where the shut-off valve 10 is closed. Exterior 12
Is provided with a cover sensor 14 for detecting the open or closed state of the carriage cover 12e. Based on a detection signal from the cover sensor 14, a control circuit of the recording apparatus main body monitors the open / closed state of the carriage cover 12e. ing.

The exterior 12 is provided with operation buttons 12g for opening and closing a switch 15 as operation input means. The operation button 12g is pressed when an operator (user) desires a predetermined operation of the ink jet recording apparatus, and inputs a request signal to a control circuit of the recording apparatus main body through the switch 15. A plurality of operation buttons 12g and switches 15 corresponding to specific operations among various operations of the inkjet recording apparatus are provided.
The control circuit provided as control means in the main body of the ink jet recording apparatus controls the operation of the recording apparatus, that is, the operation of the recording head 1, the movement of the carriage 2, the pump motor 7 and the like.
d and the drive of the cam control motor 7g are controlled. Therefore, the above-described ink filling operation and the following exchange operation of the main tank 4 and the recording head 1 are controlled by the control circuit.

Next, the replacement operation of the main tank 4 will be described.

First, in a state where the tank cover 12a is closed and the replacement of the main tank 4 is prevented, when the operator presses the operation button 12g corresponding to the replacement operation of the main tank 4, the recording operation is performed. Stops its operation, and during the operation of filling the recording head 1 with ink or during the operation of writing information from the memory writing circuit to the memory element 4m, that is, during the access to the memory element 4m, until the operation is completed. After waiting, the cam control motor 7g is driven to rotate forward, and the cams 7b and 7f are rotated until the position of b comes into contact with the suction cap 7a and the link 7e.
Then, the shutoff valve 10 is closed, and the flow path from the main tank 4 to the recording head 1 is shut off.

Subsequently, the cam control motor 7g is driven to rotate in the reverse direction to rotate the unlocking cam 7j once, and the tank cover 12
Open a. When the operator replaces the main tank 4 by attaching and detaching it and then closes the tank cover 12a, the cover sensor 13 detects that the tank cover 12a has been closed, and checks whether the memory element 4m is connected to the contact 5h. If the main tank 4 is connected to the ink supply unit 5 and the main tank 4 is connected, the replacement operation of the main tank 4 is completed. At this time, since the shutoff valve 10 is closed when the main tank 4 is removed, the ink in the ink supply needles 5a and the liquid paths 5c does not move. There is no need to worry about air entering the ink supply path.

Next, the operation of replacing the recording head 1 will be described.

In the operation of removing the recording head 1 from the carriage 2, first, the operation buttons 12 corresponding to the operation are removed.
g, if the printing operation is in progress, the operation is stopped. In addition, during the ink filling operation into the print head 1 or the information writing operation to the memory element 4m, the operation waits until the operation is completed. When the control motor 7g is driven to rotate forward, the cams 7b,
7f is rotated until the position of b contacts the suction cap 7a and the link 7e, respectively. Then, shut-off valve 1
0 is closed and the flow path from the main tank 4 to the recording head 1 is shut off. Subsequently, the cam control motor 7g is driven to rotate in the reverse direction to rotate the lock release cam 7j once, and the tank cover 12a is opened. When the operator removes the main tank 4 and closes the tank cover 12a, the cover sensor 13
Detects that the tank cover 12a is closed, confirms whether the memory element 4m is connected to the contact 5h, and confirms that the memory element 4m is not connected. , 7f are rotated until the position of c contacts the suction cap 7a and the link 7e, respectively. Then, the shut-off valve 10 is opened, and the ink ejection surface of the recording head 1 is sealed by the suction cap 7a.
This sucks ink from the discharge nozzle 1g.

When the ink is sucked for a predetermined time, all the ink from the ink supply needle 5a to the inside of the recording head 1 is sucked through the suction cap 7a. When the ink suction is completed and the carriage cover 12e is opened, the opening of the carriage cover 12e is detected by the cover sensor 14, and the cam control motor 7g is driven to rotate forward based on the detection result.
The positions of the cams 7b and 7f are a
a and the link 7e until it contacts. As a result, the suction cap 7a is separated from the ink ejection surface of the recording head 1, and subsequently, the carriage 2 is moved to a position directly below the head replacement hole 12f, so that the inhibition of the replacement operation of the recording head 1 is released. The head 1 is set in a removable state.

According to the above procedure, the recording head 1 cannot be removed earlier than the main tank 4, and the ink does not flow back to the main tank 4. Further, since all the ink in the ink supply path has been removed, even if the recording head 1 is removed, the ink does not leak from the ink supply needle 5a. As another method, the recording head 1 can be removed with the shut-off valve 10 closed.

When the recording head 1 and the main tank 4 are mounted, if the above state is satisfied,
A new recording head 1 is attached to the carriage 2 as it is. First, in a state where the recording head 1 and the ink tank 4 are both removed in this manner, the carriage 2 is positioned at the replacement position of the recording head 1 so that the recording head 1 can be replaced. When the recording head 1 is attached to the carriage 2 and the carriage cover 12e is closed to prevent the recording head 1 from being replaced, the cover sensor 14 detects that the recording head 1 is closed, and the contact 2a on the carriage 2 detects the closed state. The presence or absence of the recording head 1 is checked. When it is detected that the recording head 1 is present, the carriage 2 moves to a position for performing a suction operation by the recovery unit 7, that is, a position for performing a capping operation by the suction cap 7a, and moves the cam control motor 7g forward. The cams 7b and 7f are rotated to rotate until the position of b contacts the suction cap 7a and the link 7e. As a result, the shutoff valve 10 is closed, and the suction cap 7a is in a state in which the ink ejection surface of the recording head 1 is sealed.

Subsequently, the cam control motor 7g is driven to rotate in the reverse direction to rotate the unlocking cam 7j once, and the tank cover 12
Open a. When the operator mounts the main tank 4 on the ink supply unit 5 and closes the tank cover 12a, the cover sensor 13 detects that the cover is closed, and checks whether the memory element 4m is connected to the contact 5h. If it is connected and the main tank 4 is attached to the ink supply unit 5, the above-described ink filling operation is performed, and the mounting operation is completed. Even in this case, the recording head 1 is moved to the carriage 2
The main tank 4 is not attached to the ink supply unit 5 in a state where the ink supply unit 5 is not attached thereto, and air is introduced from the ink supply needle 5a in the main tank 4 and ink does not flow backward to the buffer chamber 5f.

Further, in such a configuration, since the operation of unlocking the tank cover 12a is performed by the reverse rotation of the cam control motor 7g constituting the recovery unit 7, the drive for unlocking the lock is performed. There is no need to provide means separately from the cam control motor 7g. Therefore,
There is no need to add a motor for unlocking the tank cover 12a or a control circuit therefor, and the above effects can be obtained without increasing the cost.

As described above, in the ink jet recording apparatus of this embodiment, the ink tank can be replaced, for example, the valve provided in the ink supply path is closed, or the ink of the attached recording head can be replaced. If the ejection operation of the ink is stopped, the suction operation of the ink in the print head by the suction unit is stopped, or the memory element attached to the ink tank is not accessed, the tank replacement is prevented. By releasing the means, air does not enter the ink supply path when the ink tank is replaced, and the memory element of the ink tank is not destroyed when the tank tank is replaced. In addition, when the recording head can be replaced, for example, when there is no ink in the ink supply path, or when a valve provided in the ink supply path is closed, the recording is canceled by releasing the head replacement prevention means. The recording head can be replaced so that air does not enter the ink supply path in a state where the recording operation after the head replacement is possible. When replacing the ink tank or the print head in a state other than those described above, the operation being performed is terminated, and then the tank replacement prevention means or the head replacement prevention means is released. Problems such as entry of air into the supply path can be reliably eliminated.

[0116]

As described above, according to the present invention, the ink supply is provided by providing the ink jet recording apparatus with a tank replacement preventing means for preventing the ink tank from being replaced except when the ink tank can be replaced. The state in which the valve provided in the path is closed, the state in which the recording head is not performing the recording operation, the state in which the suction operation of the ink in the recording head by the suction means is stopped, the memory element attached to the ink tank When the ink tank is not being accessed, the replacement prevention means is released, and when the ink tank is replaced in any other state, the operation being performed is terminated, and then the tank replacement prevention is released. Problems such as air entering the ink supply path when replacing the ink tank and the memory element of the ink tank being destroyed when replacing the tank tank No.

Further, by providing the ink jet recording apparatus with a head replacement preventing means for preventing the recording head from being replaced except in a state where the recording head can be replaced, it is possible to prevent the ink from being supplied in the ink supply path or the ink supply. When the valve provided in the path is closed or the like, the head replacement prevention means is released to allow ink to leak from the ink supply path when the print head is replaced, or to perform a printing operation after the print head is replaced. It is possible to replace the recording head without the problem that air enters the ink supply path in a state where the printing is possible.

When both the recording head and the ink tank are newly installed, the above-mentioned problem can be eliminated by controlling the operation of each exchange preventing means so that the recording head and the ink tank are installed in this order. Becomes
When removing the print head, first remove the ink tank, then suction and discharge the ink in the ink supply path by the suction means, and then remove each print prevention head so that the print head is removed. By controlling, the above problem is avoided.

Further, as the head replacement preventing means, a means for permitting the replacement of the recording head by opening the cover member covering the recording head only when the carriage on which the recording head is mounted is stopped at a predetermined position is used. As a blocking means, a cover for covering the ink tank is provided above the ink tank, and the cover is normally locked for opening and closing, and is unlocked at the time of replacement. The unlocking of the ink tank cover is performed by suction. By using the driving of the means, the countermeasure against the above problem can be realized without increasing the cost of the recording apparatus.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a basic principle of ink supply in an ink jet recording apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating a schematic configuration of an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 3 is a diagram for explaining an ink supply path for one color in the ink jet recording apparatus shown in FIG.

FIG. 4 is a diagram illustrating the behavior of air and ink in a liquid path of an ink supply unit when air is introduced into a main tank in the ink supply path shown in FIG. 2;

FIG. 5 is a diagram illustrating pressure due to a head difference between nozzles in the ink supply path shown in FIG. 2;

FIG. 6 is a diagram of an ink supply system in a conventional tube supply type ink jet recording apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording head 1a Connector insertion opening 1b Sub tank part 1c Filter 1d Opening 1e Partition part 1f Liquid chamber 1g Discharge nozzle 1h Elastic member 1i Pressure adjustment chamber 1j Electric board 2 Carriage 2a Contact 3 Transfer roller 4 Main tank 4a Case 4b, 4c Rubber Stopper 4m Memory element 5 Ink supply unit 5a Ink supply needle 5b Atmosphere introduction needle 5c, 5d, 5e Liquid path 5f Buffer chamber 5g Atmospheric communication port 5h Contact 6 Supply tube 7 Recovery unit 7a Suction cap 7b, 7f Cam 7c Suction pump 7d Pump Motor 7e Link 7g Cam control motor 7h Pendulum gear 7j Unlocking cam 7m, 7n Gear 9 Ink 9a Tip 9b Ink upper surface 9c Ink upper surface 10 Shutoff valve 10a Diaphragm 10b Holder 10c Press spring 10d Lever 11 Cover lock 11c, 12c Lock claw 12 Exterior 12a Tank cover 12c Lock claw 12e Carriage cover 12f Head replacement hole 12g Operation buttons 13, 14 Cover sensor 15 Switch S Recording sheet

Claims (21)

[Claims] An ink stored in a replaceable ink tank is supplied to a recording head having a discharge nozzle, and a negative pressure is applied to the ink in the discharge nozzle by a difference in height between the ink tank and the discharge nozzle. An ink supply path for supplying ink, a valve provided in the ink supply path to open and close the path, and suction means capable of sucking ink in the recording head from the discharge nozzle only at a predetermined time. The apparatus according to claim 1, further comprising a tank replacement preventing unit that prevents replacement of the ink tank except for a state where the ink tank can be replaced. 2. A method according to claim 1, wherein the ink contained in the ink tank is supplied to an exchangeable recording head having a discharge nozzle, and a negative pressure is applied to the ink in the discharge nozzle by a difference in height between the ink tank and the discharge nozzle. An ink supply path for supplying ink, a valve provided in the ink supply path to open and close the path, and suction means capable of sucking ink in the recording head from the discharge nozzle only at a predetermined time. The apparatus according to claim 1, further comprising a head replacement preventing unit configured to prevent replacement of the recording head except for a replaceable state of the recording head. 3. An ink stored in a replaceable ink tank is supplied to a replaceable recording head having a discharge nozzle, and an ink in the discharge nozzle is formed by a difference in height between the ink tank and the discharge nozzle. An ink supply path for applying a negative pressure to the ink, a valve provided in the ink supply path to open and close the path, and a suction unit capable of suctioning the ink in the recording head from the discharge nozzle only at a predetermined time. An ink jet recording apparatus, comprising: a tank replacement preventing unit for preventing replacement of the ink tank except for a replaceable state of the ink tank; and preventing replacement of the print head except for a replaceable state of the print head. An ink jet recording apparatus comprising: a head replacement preventing unit. 4. The replaceable state of the ink tank is as follows.
4. The ink jet recording apparatus according to claim 1, wherein the valve is in a closed state. 5. The replaceable state of the ink tank is as follows.
The inkjet recording apparatus according to claim 1, wherein the recording head is mounted on the inkjet recording apparatus. 6. The replaceable state of the ink tank is as follows.
4. The ink jet recording apparatus according to claim 1, wherein a suction operation of the ink in the recording head by the suction unit is stopped. 5. 7. The replaceable state of the ink tank is as follows.
4. The ink jet recording apparatus according to claim 1, wherein a discharge operation of the ink from the discharge nozzle is stopped. 5. 8. The replaceable state of the recording head is a state in which there is no ink in the ink supply path.
Or the inkjet recording apparatus according to 3. 9. The ink jet recording apparatus according to claim 2, wherein the exchangeable state of the recording head is a state in which the valve is closed. 10. An ink chamber for storing ink supplied from the ink tank is provided in the recording head, and a suction operation is performed by the suction means in a state where the valve is closed. The ink jet recording apparatus according to any one of claims 1 to 9, further comprising control means for opening the valve when the pressure is reduced to a pressure to fill the ink chamber with ink from the ink tank. 11. In a state in which both the recording head and the ink tank are removed, inhibition of the exchange of the recording head by the head exchange inhibiting means is released.
4. The ink jet recording according to claim 3, further comprising control means for preventing the exchange of the recording head by the head exchange preventing means after the mounting of the recording head and canceling the inhibition of the exchange of the ink tank by the tank exchange preventing means. apparatus. 12. A control unit for controlling an operation of the ink jet recording apparatus, and an operation input unit for inputting a signal for controlling an operation of the ink jet recording apparatus to the control unit, wherein the control unit The ink jet recording apparatus according to claim 1, wherein, in response to a signal from the operation input unit, the valve is closed, and inhibition of the exchange of the ink tank by the tank exchange inhibition unit is released. 13. A control unit for controlling the operation of the ink jet recording apparatus, and an operation input unit for inputting a signal for controlling the operation of the ink jet recording apparatus to the control unit, wherein the control unit 4. The ink jet recording apparatus according to claim 2, wherein the valve is closed in accordance with an input signal from the input unit, and the inhibition of the exchange of the recording head by the head exchange inhibiting unit is released. 14. A control means for controlling the operation of the ink jet recording apparatus, and an operation input means for inputting a signal for controlling the operation of the ink jet recording apparatus to the control means, wherein the control means However, after terminating the recording operation by the recording head according to a signal from the operation input unit,
4. The ink jet recording apparatus according to claim 1, wherein, after the recording operation is completed, the inhibition of the replacement of the ink tank by the tank exchange inhibiting means is released. 15. An ink jet recording apparatus comprising: control means for controlling the operation of the ink jet recording apparatus; and operation input means for inputting a signal for controlling the operation of the ink jet recording apparatus to the control means. However, after terminating the recording operation by the recording head according to a signal from the operation input unit,
4. The ink jet recording apparatus according to claim 2, wherein after the recording operation is completed, the prevention of the replacement of the recording head by the head replacement preventing unit is released. 5. 16. A control unit for controlling an operation of the ink jet recording apparatus, and an operation input unit for inputting a signal for controlling an operation of the ink jet recording apparatus to the control unit, wherein the control unit However, in accordance with a signal from the operation input means, after the suction operation of the ink in the recording head by the suction means is completed, the inhibition of the ink tank exchange by the tank exchange inhibition means is released. The inkjet recording apparatus according to claim 1 or 3. 17. A control unit for controlling an operation of the ink jet recording apparatus, and an operation input unit for inputting a signal for controlling the operation of the ink jet recording apparatus to the control unit, Releases the inhibition of the ink tank replacement by the tank replacement prevention means in response to a signal from the operation input means, and removes the ink in the ink supply path after the ink tank is removed from the ink supply path. 4. The ink jet recording apparatus according to claim 3, wherein after the ink is extracted by the suction operation of the suction unit, the inhibition of the exchange of the recording head by the head exchange inhibition unit is released. 18. A rewritable nonvolatile memory element mounted on the ink tank for managing the remaining amount of ink in the ink tank, and a recording apparatus main body on which the ink tank is replaceably mounted. A contact provided with the memory element, and a memory writing circuit provided in the recording apparatus main body and writing the remaining amount of ink in the ink tank into the memory element as information; 4. The ink jet recording apparatus according to claim 1, wherein replacement of the ink tank is prevented while the memory writing circuit accesses the memory element. 19. The ink jet recording apparatus according to claim 1, further comprising a driving unit for driving the suction unit, wherein the tank replacement preventing unit is driven by the driving unit. 20. The tank replacement preventing means has a cover member for covering the ink tank, and a lock means for locking the cover member so that the cover member is not opened when the cover member is closed, 4. The ink jet recording apparatus according to claim 1, further comprising a release unit that releases the lock of the cover member by the lock unit when the ink tank is replaceable. 21. The head replacement prevention means, comprising: a cover member that covers the recording head above the recording head when the carriage on which the recording head is mounted and moves moves to a predetermined position; 4. The ink jet recording apparatus according to claim 2, wherein the cover is opened only when the recording head is stopped at the predetermined position, thereby allowing the recording head to be replaced.