JP2002248779A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a low-cost ink jet recorder without a sequence complicated for controlling a driving means when driving a shut-off valve and a suction means even when the shut-off valve is set to an ink supply passage, and the suction means for sucking ink in a recording head from a discharge nozzle is set to the recorder. SOLUTION: An ink supply unit 5 to which a main tank 4 is detachably set and which has the shut-off valve 10 is connected via a supply tube 6 to the recording head 1. A recovery unit 7 for sucking the ink in the recording head 1 from the discharge nozzle 1g is provided with a suction cap 7a for covering an ink discharge face of the recording head 1, and a cam control motor 7g and a first cam 7b for moving the suction cap. The shut-off valve 10 is opened/closed by a second cam 7f, a link 7e and a lever 10d interlocking in accordance with the driving of the cam control motor 7g.

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 an ink tank to a 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 recording head 101 connected to the main tank 104 via a supply tube 106.

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.

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 of 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.

[0016]

However, in the conventional ink jet recording apparatus shown in FIG. 6, when the recording head 101 is filled with ink, the suction cap 107 is used.
a, a driving motor 107g for driving the suction pump 107c to suck ink through the suction cap 107a, and a valve 1
A solenoid 110d for opening and closing the 10a and three driving sources (driving means) are required, and there is a problem that the cost of the ink jet recording apparatus is high. Further, when there are a plurality of drive sources corresponding to each device to be driven, there is a problem that a sequence (order of operation) becomes complicated to control each drive source.

An object of the present invention is to provide an ink jet recording apparatus for supplying ink from an ink tank to a recording head through an ink supply path, providing a valve in the ink supply path, and suctioning ink in the recording head from a discharge nozzle. Even if the means is provided in the recording apparatus, the sequence for controlling the driving means of those valves and the suction means does not become complicated,
An object of the present invention is to provide a low-cost inkjet recording apparatus.

[0018]

In order to achieve the above object, the present invention provides a recording head having an ink chamber for storing ink and a discharge nozzle for discharging ink from the ink chamber. An ink supply path for supplying the ink, a valve provided in the ink supply path to open and close the path, 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 having a driving unit for driving the suction unit, wherein the opening and closing operation of the valve is performed by the driving unit.

Further, the recording head has an ink chamber for storing ink from the ink tank and connected to the discharge nozzle, and the ink jet recording apparatus is configured such that the recording head is operated by the suction means with the valve closed. Control for controlling the driving means so as to fill the ink chamber with ink from the ink tank by opening the valve by reducing the pressure in the ink chamber to a predetermined pressure by performing a suction operation of the ink in the ink chamber. It is preferable to have means.

Further, the suction means has cap means for covering an ink ejection surface of the recording head for ejecting ink, and the driving means has a cap position for bringing the cap means into close contact with the ink ejection surface. It is preferable that the cap means perform an operation of moving the cap means to a retreat position separated from the ink ejection surface and an operation of opening and closing the valve. In this case, the ink jet recording apparatus has a first cam for moving the cap unit to the cap position and the retreat position, and a second cam for opening and closing the valve, and the driving unit However, it is preferable that the first and second cams rotate on the same axis.

Further, a mounting portion to which the ink tank is removably mounted, a first liquid path connecting the ink tank mounted on the mounting portion to the valve, and a connecting portion for connecting the valve to the recording head. A second fluid path connecting the supply tube to the valve, and the valve, the state in which the supply tube and the valve are attached, and a flow path from the first fluid path to the supply tube was held. It is preferable that a supply unit detachable from the main body of the ink jet recording apparatus in the state is disposed adjacent to the suction unit in the ink jet recording apparatus.

According to the invention described above, in an ink jet recording apparatus, a valve is provided in an ink supply path for supplying ink from an ink tank to a recording head, and ink in the recording head is suctioned from a discharge nozzle by a suction means.
With a configuration in which the opening and closing operation of the valve is performed by the driving unit that drives the suction unit, it is not necessary to provide a separate driving source for the valve from the driving unit that drives the suction unit. The cost of the ink jet recording apparatus having the valve and the suction means is reduced. In addition, since it is not necessary to prepare separate driving means for the valve and the suction means, it is possible to control the driving means in a simple sequence.

As described above, when the driving means is for moving the cap means for covering the ink ejection surface of the recording head and for opening and closing the valve, the movement of the cap means is reciprocated. By making the movement of the valve element that constitutes the valve a reciprocating movement, the movements of both can be made similar, so that the driving means for moving the cap means can be used as a driving source for the valve. Be reasonable.

Further, the first cam for moving the cap means and the second cam for opening and closing the valve are rotated by the motor on the same axis by the driving means, so that
With a simple control of rotating the motor by a predetermined angle in one direction, a series of sequences of the suction means and the valve can be executed.

Further, the supply tube, the valve, and the mounting portion of the ink tank are provided separately from the suction means as a supply unit that can be detached from the main body of the recording apparatus without disassembling the flow path, and the supply unit is disposed adjacent to the suction means. By driving the valve via a cam or, for example, via a link by a driving unit for driving the suction unit, ink is prevented from leaking due to disassembly of parts during repair of the recording apparatus, It is possible to secure reliability against ink leakage or the like at the connection between the flow paths in the ink supply path.

[0026]

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

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 below 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 ejection nozzle 1g of the recording head 1 is a fine hole, and the ejection 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 again in the nozzle 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-mentioned 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 adhered 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). ing. Recording sheet S
Is a direction intersecting with the moving direction of the carriage 2 (for example, in a direction orthogonal to the direction in which the carriage 2 is moved) so that the conveying roller 3 faces the ink ejection surface of the recording head 1 and maintains a constant distance from the ink ejection surface. (In the direction of arrow A).

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.
It is detachably attached to the ink supply unit 5. The ink supply unit 5 and the recording head 1 are connected by a plurality of supply tubes 6 each corresponding to the color of the ink,
By attaching the main tank 4 to the ink supply unit 5, it is possible to independently supply the ink of each color stored in the main tank 4 to each nozzle row of the recording head 1. 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 the side 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 airtightly connected. Connector insertion slot 1a
Communicates with a sub-tank 1b formed as an ink chamber above the recording head 1 and storing a fixed 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. Sub tank part 1
b and the liquid chamber 1f are partitioned by the filter 1c, but an opening 1 is provided at the boundary between the sub tank 1b and the liquid chamber 1f.
The filter 1c has a partition 1e on which the filter d is formed, and the filter 1c is installed on the partition 1e. Therefore, the sub tank portion 1b is connected to each discharge nozzle 1g via the filter 1c, the opening 1d, and the liquid chamber 1f.

In the ink passage path inside the recording head 1, the ink supplied to the recording head 1 from the connector insertion port 1 a is supplied to the sub tank 1 by the above 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 this 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 this 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 adjusting chamber 1i is a chamber whose volume decreases as the internal negative pressure increases.
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 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 adjustment 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 ink, and suppresses the influence of 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 mounting portion of the main tank 4 is composed of the ink supply needle 5a and the air introduction needle 5b. 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 5 a is connected to the supply tube 6 via a first liquid path 5 c, a selectively openable / closable shutoff valve 10, and a fifth liquid path 5 d, and further communicates with the recording head 1. . The atmosphere introduction needle 5b communicates with the atmosphere via the liquid path 5e, the buffer chamber 5f, and the atmosphere communication port 5g. The first liquid path 5c at the lowest position in the ink supply path from the ink supply needle 5a to the supply tube 6, and the lowest position in the path from the air introduction needle 5b to the air communication port 5g. Are the same height. In the present embodiment, the ink supply needles 5a and the air introduction needles 5b use thick ones having an inner diameter of 1.6 mm in order to suppress the flow resistance of the ink, and the needle holes have a diameter of 1 to 1.5 mm. did.

The shutoff valve 10 has a diaphragm 10a made of a rubber material, and opens and closes between the first liquid passage 5c and the second liquid passage 5d by vertically displacing the diaphragm 10a. A pressing spring 1 is provided on the upper surface of the diaphragm 10a.
A cylindrical spring holder 10b for holding the inside of the diaphragm 10a is mounted, and the center of the diaphragm 10a is pressed by the pressing spring 10c to crush the diaphragm 10a.
When the opening surface of the liquid passage 5d is closed, the space between the first liquid passage 5c and the second liquid passage 5d is 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 and lifting the spring holder 10b against the spring force of the pressing spring 10c, the first liquid path 5c and the second liquid path 5c are lifted.
d communicates 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 configuration of the ink supply unit 5 described above 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)
The first liquid path 5c communicating with the first liquid path 5c is at the same height, and both the first liquid path 5c and the liquid path 5e are communicated only with ink. Become. This is determined by the relationship between the height of the ink tip 9a and the first liquid path 5c, and is not affected by the amount of the ink 9 in the main tank 4.

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 in which ink is accumulated in the buffer chamber 5f. In this case, the leading end 9a of the ink is located at a height h1 (mm) higher than the first liquid path 5c in the middle of the buffer chamber 5f in the height direction.
The pressure of c is -h1 (mmAq).

As described above, in the present 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 first liquid path 5c to the ink upper surface 9b in the sub tank portion 1b is h2 (mm) as shown in FIG.
If the height from the bottom 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 upper surface 9c in the liquid chamber 1f is h4 (mm), the lower end of the discharge nozzle 1g is Negative pressure _Pn is _Pn
≒ −9.8 × (h2−h3−h4) Pa, and in a state where the ink is accumulated in the buffer chamber 5f, P _n ≒ −9.8.
X (h2-h1-h3-h4) Pa. The value of _Pn is in the range of the negative pressure described above (−4.053 kPa to −2.
0265 kPa).

Referring again to FIG. 3, the ink supply needle 5a
A detection circuit 5h for measuring the electric resistance of the ink is connected to the air introduction needle 5b, and the presence or absence of the ink in the main tank 4 can be detected. This detection circuit 5h
In the state where ink is present in the main tank 4, an electric close is detected because a current flows through the detection circuit 5h via the ink in the main tank 4, and the ink is not present or the main tank 4 is mounted. If not, an electrical open is detected. Since the detection current is weak, it is important to insulate the ink supply needle 5a from the air introduction needle 5b. In the present embodiment, the path from the ink supply needle 5a to the recording head 1 and the atmosphere communication from the air introduction needle 5b to the atmosphere. The path to the mouth 5g is completely independent so that the electric resistance of only the ink in the main tank 4 can be measured.

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). It has a suction cap 7a as cap means and a link 7e for operating a 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 the like, and has a cap position for covering and sealing the ink ejection surface, and a retreat position separated from the recording head 1 and retracted. Between them. 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.
By driving the suction pump 7c with d, continuous suction is possible. Further, the suction amount can be changed according to the rotation amount of the pump motor 7d. In this embodiment,
The suction pump 7c capable of reducing the pressure to 0.4 atm (40.53 kPa) is used.

The first cam 7b operates the suction cap 7a by moving the suction cap 7a up and down between the above two positions. The second cam 7f operates the link 7e by a cam control motor 7g as a driving means. Are rotated synchronously on the same axis. The link 7e moves the lever 10d by sliding with the second cam 7f, thereby opening and closing the shutoff valve 10. The timing at which the positions a to c of the first cam 7b contact the suction cap 7a, respectively,
The positions of a to c of the second cam 7f coincide with the timing of contact with the link 7e. At the position a, the first cam 7b separates the suction cap 7a from the ink ejection surface of the recording head 1, and the second cam 7f pushes the link 7e to push up the lever 10d to open the shutoff valve 10. In the position b, the first cam 7b is
The second cam 7f pulls back the link 7e to close the shutoff valve. At position c,
The first cam 7b brings the suction cap 7a into close contact with the ink ejection surface, and the second cam 7f presses the link 7e to open the shutoff valve 10.

As described above, in the ink jet recording apparatus of this embodiment, the shutoff valve 10 is driven to open and close by the cam control motor 7g that drives the suction cap 7a. Therefore, the shutoff valve 10 is provided in the ink supply path, and the recording head 1
Even when the ink inside is sucked by the recovery unit 7, it is not necessary to provide a drive source for the shutoff valve 10 separately from the cam control motor 7 g, and the ink jet recording apparatus having the shutoff valve 10 and the recovery unit 7 Costs are reduced. In addition, since it is not necessary to prepare separate driving means for the shutoff valve 10 and the recovery unit 7, the movement of the suction cap 7a and the opening and closing of the shutoff valve 10, that is, the driving of the cam control motor 7g are controlled in a simple sequence. It is possible to do.

Further, as described above, the movement of the suction cap 7a is a reciprocating movement between the cap position and the retracted position, and the opening / closing operation of the shutoff valve 10 is a reciprocating movement of the central portion of the diaphragm 10a, that is, a reciprocating movement of the valve body. Since the movement is the same, both of the operations become the same, and it is reasonable to use the cam control motor 7g for moving the suction cap 7a as a drive source of the shutoff valve 10. Further, by a configuration in which the first cam 7b and the second cam 7f are rotated by the cam control motor 7g on the same axis, a simple control of rotating the cam control motor 7g by a predetermined angle in one direction. With suction cap 7a and shut-off valve 10
Can be executed. A control circuit provided as a control means in the main body of the inkjet 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 driving of the pump motor 7d and the cam control motor 7g, and the like. I have. Therefore, an operation of filling the recording head 1 with ink as described later is controlled by the control circuit.

In the recording operation, the first cam 7b and the second cam 7f are set at the position a, the suction cap 7a is separated from the ink discharge surface, the shutoff valve 10 is opened, and the ink from the discharge nozzle 1g is discharged. And supply of ink from the main tank 4 to the recording head 1 is enabled. At the time of non-operation including standby and suspension, the first cam 7b and the second cam 7f are set to the position b, and the suction cap 7a covers the ink discharge surface to prevent the discharge nozzle 1g from drying and shut off. The valve 10 is closed to prevent the ink from flowing out of the recording head 1 (especially when the apparatus itself moves, the apparatus may be tilted and the ink may flow out). The positions of c of the first cam 7b and the second cam 7f are used at the time of the ink filling operation of the recording head 1 described below.

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.

Therefore, 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 drive the first cam 7b. And the second cam 7f
Are rotated until the position of b comes into contact with 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 first cam 7b and the second cam 7f until the position c contacts the suction cap 7a and the link 7e, respectively. As a result, the shut-off valve 10 is opened while keeping the state of the ink discharge surface sealed by the suction cap 7a. 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 shut-off valve 10 is opened, ink flows into the recording head 1 under reduced pressure via the supply tube 6, and the sub-tank 1b and the liquid chamber 1f are filled with 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 sub tank 1b and the liquid chamber 1f with ink 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 to drive the first cam 7b and the second cam 7f to a
Are rotated to positions where they contact the suction cap 7a and the link 7e, respectively. As a result, the suction cap 7a is separated from the recording head 1, and again the suction pump 7c
Is driven to suck the ink remaining in the suction cap 7a. In this state, since the shut-off valve 10 is in the open state, the ink is discharged from the discharge nozzle 1g to form a state in which characters, images, and the like can be formed on the recording sheet S (see FIG. 2). During standby and rest, the cam control motor 7g is driven again to rotate the first cam 7b and the second cam 7f to positions where the position b contacts the suction cap 7a and the link 7e, respectively. Then, the ink ejection surface of the recording head 1 is sealed with the suction cap 7a, and the shutoff valve 10 is closed.

The recovery unit 7 includes a suction cap 7
Since there are many movable parts such as a and a tube connected thereto, and the conditions such as the sealing property of the suction cap 7a with respect to the ink ejection surface of the recording head 1 are severe (strict), the components of the recovery unit 7 are recording. This is the part that tends to be replaced most frequently in the equipment. Therefore, as in the present embodiment, the recovery unit 7 needs to be separated from the ink supply unit 5 having the cutoff valve 10 and the mounting portion of the main tank 4. In the present embodiment, the ink supply unit 5 can be detached from the main body of the recording apparatus with the shutoff valve 10 and the supply tube 6 attached to the ink supply unit 5, that is, the shutoff valve 10 and the supply tube 6 can be removed from the ink supply unit 5. Can be detached from the recording apparatus main body without removing it. Therefore, the ink supply needle 5
a, the first fluid path 5c, the shut-off valve 10, and the second fluid path 5
The ink supply unit 5 can be removed from the recording apparatus main body without dismantling the flow path through d to the supply tube 6. This prevents ink dripping when the components are disassembled for repairing the recording apparatus, and does not cause damage (damage) at the joint between the components due to attachment and detachment of the ink supply unit 5, thereby improving repair workability. I do. In addition, since the ink supply unit 5 can be removed without disassembling the flow path from the ink supply needle 5a to the supply tube 6 at the time of repair or the like, the leakage of the link at the connection between the flow paths in the ink supply path is achieved. Reliability can be ensured.

By disposing the ink supply unit 5 adjacent to the recovery unit 7 in the ink jet recording apparatus, the cam control motor 7g, the second cam 7f, and the link 7e makes it relatively easy to drive.

[0089]

As described above, the present invention relates to a construction in which a valve is provided in an ink supply path for supplying ink from an ink tank to a recording head, and ink in the recording head is sucked from a discharge nozzle by suction means. Also, by adopting a configuration in which the opening and closing operation of the valve is performed by the driving unit that drives the suction unit, it is not necessary to prepare a driving source separate from the driving unit for the suction unit for the valve. There is an effect that the cost of the ink jet recording apparatus having the suction means is reduced. In addition, since it is not necessary to prepare separate driving means for the valve and the suction means, it is possible to control the driving means in a simple sequence.

In the case where the driving means moves the cap means for covering the ink discharge surface of the recording head to a cap position which is in close contact with the ink discharge surface and a retracted position which is separated from the ink discharge surface, For example, by making the movement of the valve body constituting the valve a reciprocating movement, the operation of both the cap means and the valve can be made the same, so that the driving means for moving the cap means is used as a drive source for the valve. There is an effect that it is rational to do so.

Further, the first cam for moving the cap means and the second cam for opening and closing the valve are rotated by the motor on the same axis by the driving means, so that the motors become one. There is an effect that a series of sequences of the suction means and the valve can be executed by a simple control of rotating and driving at a predetermined angle in the direction.

Further, a mounting portion of the ink tank,
A valve, a supply tube for connecting the valve to the recording head, is a supply unit that can be detached from the recording apparatus main body without dismantling the flow path, separately from the suction means, and the supply unit is arranged adjacent to the suction means. By driving the valve via a cam by a driving unit for driving the suction unit, or via, for example, a link, it is possible to prevent ink from leaking due to disassembly of parts when the recording apparatus is repaired. The reliability with respect to ink leakage or the like can be ensured at the connection between the flow paths in the supply path.

[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 port 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 point 3 Transport roller 4 Main tank 4a Case 4b, 4c Rubber Stopper 5 Ink supply unit 5a Ink supply needle 5b Atmosphere introduction needle 5c First liquid path 5d Second liquid path 5e Liquid path 5f Buffer chamber 5g Atmospheric communication port 5h Detection circuit 6 Supply tube 7 Recovery unit 7a Suction cap 7b First cam 7f Second cam 7c Suction pump 7d Pump motor 7e Link 7g Cam control motor 9 Ink 9a Tip 9b Ink upper surface 9c Ink upper surface 10 Shut off valve 10a Diaphragm 10b Holder 10c Press spring 10d Lever S Recording sheet

Claims (5)

[Claims] An ink supply path for supplying ink contained in an ink tank to a recording head having a discharge nozzle for discharging ink; a valve provided in the ink supply path for opening and closing the path; In an ink jet recording apparatus having a suction unit capable of sucking ink in the recording head from the discharge nozzle only at a predetermined time, and a driving unit for driving the suction unit, the opening and closing operation of the valve is performed by the driving unit. An ink jet recording apparatus characterized by being configured as described above. 2. The recording head has an ink chamber which stores ink from the ink tank and is connected to the discharge nozzle, and a suction operation of the ink in the recording head by the suction means with the valve closed. The control means controls the driving means so as to fill the ink chamber with the ink from the ink tank by opening the valve after reducing the pressure in the ink chamber to a predetermined pressure by performing The inkjet recording apparatus according to claim 1. 3. A cap for covering the ink ejection surface of the recording head where the ejection nozzle is opened in the recording head, and the driving unit includes a cap for bringing the cap unit into close contact with the ink ejection surface. 3. The ink jet recording apparatus according to claim 1, wherein an operation of moving the cap unit to a position and a retracted position where the cap unit is separated from the ink ejection surface, and an operation of opening and closing the valve are performed. . 4. A first cam for moving the cap means to the cap position and the retreat position, and a second cam for opening and closing the valve, wherein the driving means comprises: 4. The ink jet recording apparatus according to claim 3, wherein the motor is a motor that rotates the first and second cams on the same axis. 5. A mounting portion to which the ink tank is detachably mounted, a first liquid path connecting the ink tank mounted on the mounting portion to the valve, and connecting the valve to the recording head. A second fluid path connecting the supply tube to the valve, and the valve, the state in which the supply tube and the valve are attached, and a flow path from the first fluid path to the supply tube was held. The inkjet recording apparatus according to any one of claims 1 to 4, wherein a supply unit that is detachable from a main body of the inkjet recording apparatus in a state is disposed adjacent to the suction unit in the inkjet recording apparatus.