JP2003237097A - Ink tank and inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To propose a foam type ink tank equipped with a part to be detected which can correctly detect that ink runs out by a simple constitution. <P>SOLUTION: A sub ink chamber 30 is formed between a main ink tank 5 and an ink take-out hole 7 of the foam type ink tank 100. When an amount of the air entering the sub ink chamber increases, reflecting faces 52a and 52b of a rectangular prism 52 which have been an ink interface return to reflecting faces and can accordingly detect an ink end. A member 110 having a surface repellency is set in the sub ink chamber 30. Bubbles generated in the sub ink chamber 30 burst through contact with the member 110 and gather into a large bubble to disappear eventually. Since an amount of bubbles in the sub ink chamber 30 is made small, such trouble can be eliminated that rear faces of the reflecting faces 52a and 52b are kept covered with the ink held between the bubbles and a reflecting state of the reflecting faces 52a and 52b is unchanged in spite of a decrease in an ink level S, resulting in a detection failure of the ink end. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink tank provided with a foam that absorbs and holds ink, and more particularly to an ink tank provided with a detected portion capable of accurately detecting a state where ink is exhausted (ink end). It is a thing. The present invention also relates to an inkjet printer using such an ink tank as an ink supply source.

[0002]

2. Description of the Related Art Foam type ink tanks are known as ink tanks for ink jet printers. This foam-type ink tank has a foam storage section that stores a foam that absorbs and holds ink, an ink outlet that communicates with this foam storage section, and a vent that opens the foam storage section to the atmosphere. is doing. When the ink is sucked from the ink take-out hole by the ejection pressure of the ink jet head, the air corresponding to the sucked ink amount flows into the foam storage portion from the vent hole.

In the case of a foam type ink tank, the presence or absence of ink is detected based on the number of ink dots ejected from the ink jet head, the ink suction amount of an ink pump sucking ink from the ink jet head, and the like. The amount of the ejected ink is counted, and the counting is performed based on the count result.

Generally, a state in which the ink in the ink tank is almost exhausted is called "real end", and a state in which the remaining amount of ink in the ink tank is less than a certain amount is called "near end". However, the “ink end” used in the present specification includes both unless otherwise specified.

[0005]

However, the ink end detection method for detecting the ink end by counting the ink usage amount has the following problems. Since the amount of ink ejected from the inkjet head and the amount of ink sucked by the ink pump vary, the amount of ink used, which is counted based on these amounts, greatly varies from the actual amount of ink used. Therefore, it is necessary to provide a large margin in order to determine the ink end. As a result, a large amount of ink may remain at the time when the ink end is detected, and the ink is often wasted.

Therefore, the back surface of the prism reflection surface is used as an ink interface, and when the ink is exhausted, the prism end reflection surface returns to the original reflection surface. It is possible to detect it. A detection system using a prism reflection surface is disclosed in, for example, Japanese Patent Laid-Open No. 10-323993 and US Pat. No. 5,616,929.

However, in the case of a foam type ink tank, since the ink is absorbed and held in the foam, the detection system disclosed in the above publication cannot be applied as it is.

The object of the present invention is to solve the above problems.
An ink tank having a detected portion capable of accurately detecting an ink end in a foam type ink tank by utilizing a reflection surface whose back surface is an ink interface, and an inkjet printer using the ink tank as an ink supply source. To propose.

[0009]

In order to solve the above-mentioned problems, an ink tank of the present invention comprises a foam in which ink is absorbed and held, a main ink chamber in which the foam is stored and which is open to the atmosphere. An auxiliary ink that is formed between the ink outlet and the main ink chamber and the ink outlet, and is capable of introducing ink and bubbles from the side of the main ink by the ink suction force acting on the ink outlet. Chamber and a detected portion capable of optically detecting whether or not ink has run out based on the amount of air that has entered the sub ink chamber from the main ink chamber, and the detected portion is the sub ink chamber. In the above, the back surface is provided with a reflection surface serving as an ink interface, and the reflection surface back surface serving as the ink interface is characterized by being subjected to a water repellent treatment.

According to the present invention, the sub-ink chamber is formed between the main ink chamber and the ink take-out hole, and when the ink remaining in the main ink chamber becomes small, the main ink chamber is supplied every time the ink is supplied from the ink take-out hole. From this, bubbles come into the sub ink chamber. When the ink in the main ink chamber is used up, the amount of ink remaining in the ink tank is substantially only the amount of ink stored in the sub ink chamber. When the amount of remaining ink in the sub ink chamber becomes small, the back surface of the reflecting surface, which is the ink interface, is exposed from the ink liquid surface, and the reflecting state of the reflecting surface changes. That is, the reflecting surface, which did not function as a reflecting surface when the back surface was covered with ink, gradually regained the reflecting function as the ink liquid level decreased. Therefore, it is possible to detect the state in which the remaining amount of ink is equal to or less than the predetermined amount based on the amount of light reflected by the reflecting surface. Therefore, if the volume of the sub ink chamber is made sufficiently small, the ink end can be detected when the remaining amount of ink is substantially exhausted.

In addition to this, in the present invention, since the back surface of the reflecting surface, which is the ink interface, is a water-repellent treated surface, bubbles do not adhere to the back surface of the reflecting surface and adhere to the back surface of the reflecting surface. The generated bubbles burst and disappear due to the water repellency of the back surface of the reflecting surface. Therefore, it is possible to avoid a situation in which the bubbles generated in the sub-ink chamber adhere to the back surface of the reflecting surface or float in the vicinity thereof and the reflecting surface is covered with the ink held between the bubbles.

As a result, even though the liquid level of the ink in the sub ink chamber is lower than that of the reflecting surface, the reflecting surface remains covered with the ink held between the air bubbles, and the reflecting state of the reflecting surface is changed. It is possible to avoid the adverse effect that the ink end cannot be detected without changing.

Here, if at least a part of the inner surface of the sub ink chamber adjacent to the back surface of the reflection surface is also a water-repellent surface, the bubbles generated in the sub ink chamber will be the back surface of the reflection surface. It can be prevented from adhering to or floating in the vicinity thereof. Further, it is possible to more reliably eliminate the bubbles floating near the back surface of the reflecting surface.

Next, in the present invention, the surface subjected to the water repellent treatment may be a surface coated with a water repellent material. In this case, a fluorine-based coating material can be used as the water repellent material. Further, as the fluorine-based coating material, a fluoroolefin-based polymer or a fluorine-containing acrylic coating material can be used.

On the other hand, in the present invention, the reflecting surface may be a pair of prism reflecting surfaces orthogonal to each other.

Next, in order to allow bubbles to be introduced from the main ink chamber into the sub ink chamber by the ink suction force acting on the ink outlet, the main ink communicating with the sub ink chamber is connected to the main ink chamber. A first filter may be attached to the chamber side communication port, and the first filter may be formed of a porous material through which air bubbles can pass by the ink suction force acting on the ink outlet.

In this case, in order to prevent bubbles generated in the sub ink chamber from being discharged to the ink take-out hole side, the take-out hole side communication port communicating the sub-ink chamber and the ink take-out hole is A second filter may be attached and the second filter may be formed of a porous material having a smaller pore size than the first filter.

Next, the ink tank of the present invention comprises a foam in which ink is absorbed and held, a main ink chamber in which this foam is stored, which is open to the atmosphere, and an ink outlet hole.
A sub-ink chamber formed between the main ink chamber and the ink take-out hole, capable of introducing ink and bubbles from the side of the main ink chamber by an ink suction force acting on the ink take-out hole; A detected portion capable of optically detecting whether or not ink has run out based on the amount of air that has entered the sub-ink chamber from the ink chamber; and a surface water-repellent member disposed in the sub-ink chamber, The part to be detected is characterized by having a reflection surface whose back surface is an ink interface in the sub ink chamber.

Also in the ink tank of the present invention, when the sub ink chamber is formed between the main ink chamber and the ink take-out hole and the amount of ink remaining in the main ink chamber becomes small, ink is supplied from the ink take-out hole every time. Bubbles come into the sub ink chamber from the main ink chamber. When the ink in the main ink chamber is used up, the amount of ink remaining in the ink tank is substantially only the amount of ink stored in the sub ink chamber. When the amount of remaining ink in the sub ink chamber becomes small, the back surface of the reflecting surface, which is the ink interface, is exposed from the ink liquid surface, and the reflecting state of the reflecting surface changes. That is, the reflecting surface, which did not function as a reflecting surface when the back surface was covered with ink, gradually regained the reflecting function as the ink liquid level decreased. Therefore, it is possible to detect the state in which the remaining amount of ink is equal to or less than the predetermined amount based on the amount of light reflected by the reflecting surface. Therefore, if the volume of the sub ink chamber is made sufficiently small, the ink end can be detected when the remaining amount of ink is substantially exhausted.

Further, since the surface water-repellent member is disposed in the sub ink chamber, when the air bubbles in the sub ink chamber come into contact with the surface water repellent member, the bubbles of the ink having a thin bubble surface are formed. The film pops up on the surface of the water-repellent member and collects into larger bubbles. When the bubbles become larger than a certain amount, the interfacial tension of the thin ink film becomes smaller than the internal pressure of the bubbles, and the bubbles burst and disappear. Therefore, it is possible to avoid a situation in which the bubbles generated in the sub-ink chamber adhere to the back surface of the reflecting surface or float in the vicinity thereof and the reflecting surface is covered with the ink held between the bubbles.

As a result, even though the liquid level of the ink in the sub ink chamber is lower than that of the reflecting surface, the reflecting surface remains covered with the ink held between the bubbles, and the reflecting state of the reflecting surface is changed. It is possible to avoid the adverse effect that the ink end cannot be detected without changing.

Here, as the surface water-repellent member,
A polytetrafluoroethylene-based member or a polypropylene-based foam can be used.

Further, if the surface water-repellent member is placed in the sub ink chamber so as to be able to float on the ink liquid surface, it floats on the ink liquid surface in the sub ink chamber as the ink is consumed. The surface water-repellent member is being lowered along with the ink surface. Therefore, the bubbles filled in the space above the ink surface can be efficiently eliminated.

Next, the reflecting surface in the present invention may be a pair of prism reflecting surfaces which are orthogonal to each other.

On the other hand, in order to allow bubbles to be introduced from the main ink chamber into the sub ink chamber by the ink suction force acting on the ink outlet, the main ink chamber communicating with the sub ink chamber A first filter may be attached to the side communication port, and the first filter may be formed of a porous material through which air bubbles can pass by the ink suction force acting on the ink outlet.

In this case, in order to prevent the air bubbles generated in the sub ink chamber from being discharged to the ink take-out hole side, the take-out hole side communication port communicating the sub ink chamber and the ink take-out hole is A second filter may be attached and the second filter may be formed of a porous material having a smaller pore size than the first filter.

Next, the present invention relates to an ink jet printer using the ink tank of the above construction as an ink supply source, and is characterized in that it is provided with a detection section capable of detecting a detected section of the ink tank. In the inkjet printer according to the present invention, the ink end of the ink tank can be reliably detected.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an ink tank to which the present invention is applied will be described below with reference to the drawings. The following embodiments are examples in which the present invention is applied to an ink tank that is detachably attached to a tank attachment portion of an inkjet printer. However, the present invention can be similarly applied to an ink tank that is previously arranged in an inkjet printer.

[First Embodiment] (Overall Structure) FIGS. 1A and 1B are a plan view and a front view showing a foam type ink tank according to a first embodiment of the present invention, and FIG. FIG. 4 is a perspective view of the ink tank when viewed from the bottom side, and FIG. 3 is an exploded perspective view of the ink tank.

The ink tank 1 of this embodiment is detachably attached to a tank attachment portion (not shown) formed in an ink jet printer (not shown) for use.
The ink tank 1 has a rectangular parallelepiped container body 2 having an open upper side, and a container lid 4 that closes the upper opening 3, and a main ink chamber 5 is formed inside them.
A rectangular parallelepiped form 6 that accommodates the ink is stored.

An ink take-out hole 7 is formed on the bottom surface of the container body 2, and a disk-shaped rubber packing 8 is attached to the ink take-out hole 7, and a through hole 8a opened at the center thereof takes out the ink. It is said to be a mouth. A valve 9 capable of closing the ink outlet 8a is arranged in a portion of the ink outlet 7 that is deeper than the rubber packing 8, and the valve 9 is constantly pressed by the coil spring 10 against the rubber gasket 8 to remove the ink. The mouth 8a is closed.

The main ink chamber 5 communicates with the ink take-out hole 7 through the sub ink chamber 30 partitioned by the first filter 11 and the second filter 12. Further, the atmosphere is opened to the atmosphere through an atmosphere communication hole 13 formed in the container lid 4. Therefore, when the ink absorbed and held in the foam 6 mounted in the main ink chamber 5 is sucked through the ink take-out hole 7, the air corresponding to the sucked ink is mainly discharged from the atmosphere communication port 13. Enter the ink chamber 5.

The atmosphere communication hole 13 of the container lid 4 is connected to a curved groove 13a carved on the surface of the container lid, and the end 13b of the groove 13a extends to the vicinity of the edge of the container lid 4. . At the time of shipping the ink tank 1, a seal 14 is attached to a portion of the container lid 4 where the atmosphere communication hole 13 and the groove 13a are formed.
A part 1 of the seal 14 along the cutting line 14a of 4
By peeling off 4b, the end 13b of the groove 13a is exposed and the atmosphere communication hole 13 is opened to the atmosphere.

A seal 15 is also attached to the ink outlet 8a on the bottom of the container, and the ink tank 1
When the ink jet needle is attached to the tank attachment portion of the ink jet printer, the ink supply needle attached to the tank attachment portion (see FIG.
The reference (see (b)) breaks the seal 15 and is inserted into the ink outlet 8a, so that the ink tank 1 is in the mounted state.

Next, FIGS. 4A and 4B are a sectional view and a partially enlarged sectional view of the ink tank 1 taken along line IV-IV in FIG. 1, and FIG. −
FIG. 3 is a cross-sectional view of the ink tank 1 taken along the line V,
FIG. 6 is a sectional view of the ink tank 1 taken along the line VI-VI in FIG.

With reference to these figures, the ink extraction hole 7
The structure of the ink passage portion including the sub ink chamber 30 formed between the main ink chamber 5 and the main ink chamber 5 will be described. First, in the bottom plate portion 21 of the container body 2, a tubular frame 22 having a rectangular cross section penetrates the bottom plate portion 21 and extends vertically vertically. A rectangular communication port 25 (main ink chamber side communication port) is formed at the upper end of the upper cylindrical frame portion 23 of the cylindrical frame 22 which stands upright in the main ink chamber 5. This communication port 25
A rectangular first filter 11 is attached to the.

The lower end opening of the lower tubular frame portion 24 vertically projecting downward from the container bottom plate portion 21 of the tubular frame 22 is closed by a frame bottom plate portion 24a formed integrally therewith, A cylindrical projecting portion 26 is integrally formed in a substantially central portion of the frame bottom plate portion 24a so as to extend vertically upward. The central hole of the protruding portion 26 is an ink passage 27 communicating with the ink take-out hole 7. The rubber packing 8, the valve 9 and the coil spring 10 are attached to the ink passage 27, and the spring bearing 28 of the coil spring 10 is attached. It is integrally formed on the inner peripheral surface of the protruding portion 26.

The projecting portion 26 extends to a position below the first filter 11 by a predetermined distance,
The second filter 12 is attached to the circular communication port 29 (mounting hole side communication port) formed at the upper end thereof.

The first filter 11 of this example is made of a porous material that allows air bubbles to pass therethrough by the ink suction force acting on the ink outlet 7 while allowing the ink to pass therethrough. That is, it is made of a porous material having a pore size that causes a capillarity to destroy the meniscus by the ink suction force. The first filter 11 is formed of, for example, a mesh filter.

On the other hand, the second filter 12 is made of a porous material that allows the ink to pass through but prevents bubbles from passing through due to the ink suction force acting on the ink outlet. That is, it is made of a porous material having a fine pore size that acts as a capillary force that does not destroy the meniscus due to the ink suction force. Further, the second filter 12 has a pore size capable of capturing foreign matter mixed in the ink. This second filter 12 can also be formed from a mesh filter.

Here, the ink suction force is the ink suction force that acts on the ink extraction hole 7 by the ink discharge pressure of the ink jet head (not shown) to which the ink is supplied.

Next, a cup-shaped cap 31 for sucking ink is arranged in the sub ink chamber 30 of this example.
The cup-shaped cap 31 sucks up the ink accumulated in the bottom of the sub ink chamber 30 to the communication port 29 to which the second filter 12 located above is attached.

FIGS. 7A and 7B are a perspective view and a sectional view showing the cup-shaped cap 31. Explaining with reference to FIGS. 4 to 7, the cup-shaped cap 31 includes a cylindrical body portion 32 and a top plate portion 33 that closes the upper end opening, and the lower end opening 34 has a circular shape. On the end surface 35, a plurality of protrusions formed at predetermined angular intervals vertically project. In this example, four protrusions 36 having the same height are formed at intervals of 90 degrees. The inner peripheral surface of the cylindrical body portion 32 has a lower end-side inner peripheral surface portion 37 and a tapered inner peripheral surface portion 3 which continuously protrudes inward from the upper peripheral portion 37.
8 and a small-diameter upper end side inner peripheral surface portion 39 continuous to the upper side.

The cup-shaped cap 31 of this shape is attached to the cylindrical protruding portion 26 formed in the ink chamber 30 in a capped state from the upper side. The outer peripheral surface of the projecting portion 26 has a slightly larger large diameter outer peripheral surface portion 41 on the lower end side, and a smaller diameter outer peripheral surface portion 42 on the upper end side, and an annular step surface 43 is formed therebetween. There is. As shown in FIG. 6, the small-diameter outer peripheral surface portion 4
Ribs 44 protruding outward are formed at 2 at predetermined angular intervals. In this example, four ribs 44 are formed at intervals of 90 degrees, and these ribs 44 have the same protrusion amount and have a predetermined length in the vertical direction. The amount of protrusion of these ribs 44 is such that they are cup-shaped caps 31.
It is set so as to fit exactly into the outer peripheral surface portion 39 of the upper end.

When the cup-shaped cap 31 is capped on the protruding portion 26, the cup-shaped cap 31 is positioned by the four ribs 44, and four cups are provided between the inner peripheral surface of the cup-shaped cap 31 and the outer peripheral surface of the protruding portion 26. A gap 45 having an arcuate cross section for ink suction is formed. Further, the height dimension from the lower surface of the protrusion 36 formed on the circular end surface 35 at the lower end of the cup-shaped cap 31 to the back surface of the top plate portion 33 is set to be larger than the height dimension of the protruding portion 26 by a predetermined amount. . Therefore, in the capping state, a gap 46 for ink passage is formed at a predetermined interval between the second filter 12 attached to the upper end of the protruding portion 26 and the back surface of the top plate portion 33 of the cup-shaped cap 31. The gap 46 communicates with the gap 45. Further, in the capping state, four gaps 47 having a constant width and having an arc-shaped cross section are formed between the four protrusions 36 formed at the lower end of the cup-shaped cap 31. This arcuate cross section gap 4
7 communicates with the above-mentioned gap 45 having an arcuate cross section.

Here, by setting the gaps 45, 46, and 47 to appropriate widths, ink is sucked up from the gap 47 through the gap 45 and passes through the gap 46 and the second filter 12. As a result, an ink suction passage reaching the communication port 29 at the upper end of the protruding portion can be formed. By doing so, even when the amount of ink accumulated in the sub ink chamber 30 is reduced and the liquid level thereof is lower than that of the second filter 12, the ink in the sub ink chamber 30 is kept in the second state.
Suck up to the position of the filter 12 of the ink passage 27
Can be supplied to the ink extraction hole 7.

Further, in this example, the outer peripheral surface 32a of the cup-shaped cap 31 forms the sub-ink chamber 30, and the cylindrical frame 2 is formed.
The second inner side surface 22a is separated from the inner side surface 22a by a predetermined width. Outer peripheral surface 32a of cup-shaped cap 31
When the ink comes into contact with the inner side surface 22a of the cylindrical frame 22, the inside of the sub ink chamber 30 is divided into left and right with the contact position as a boundary, and the ink accumulated in the sub ink chamber 30 cannot be sucked up efficiently. There is a risk. In this example, the cup-shaped cap 31 can efficiently suck up the ink accumulated in the sub ink chamber 30.

(Detection Unit) Next, the ink tank 1 of this example is provided with a right-angle prism 51 used for optically detecting whether or not the ink tank 1 is mounted in the mounting portion of the ink jet printer. ing. Further, a right-angle prism 52 used for optically detecting that the amount of ink remaining in the sub ink chamber 30 has fallen below a predetermined amount is arranged.

Referring to FIGS. 3, 5 and 6, a horizontally long rectangular plate 54 is adhesively fixed to the lower end portion of the side plate portion 53 of the container body 2, and the inner surface of the rectangular plate 54 is fixed. The right-angled prisms 51 and 52 are integrally formed at a fixed interval. These right angle prisms 51 and 52 are a pair of orthogonal reflecting surfaces 51a, 51b and 52, respectively.
a and 52b.

One of the right-angled prisms 51 faces the side plate portion 53 of the container body 2 via an air layer 55 having a constant gap. That is, the side plate portion 53 is formed with the concave portion 56 having a shape corresponding to the right-angle prism 51, whereby the reflecting surfaces 51a and 51b are provided on the side plate portion 53 of the main ink chamber 5 via the air layer 55 having a constant gap. They are facing each other.

On the other hand, the other rectangular prism 52
Is exposed to the inside of the sub ink chamber 30 directly through an opening 22b formed in the cylindrical frame 22 forming the sub ink chamber 30. That is, the pair of prism reflecting surfaces 52a, 52
The back surface of b is the ink interface. Therefore, when the ink surface of the sub ink chamber 30 is above the mounting position of the right-angled prism 52, the reflection surfaces 52a, 52 are formed.
b does not function as a reflecting surface in contact with ink. However, when the ink surface drops downward, the reflection surfaces 52a, 5
2b gradually regains its function as an original reflecting surface.

Next, as shown in FIG. 6, the ink tank 1
Reflective optical sensors 57 and 58 are attached to the side of the ink jet printer (not shown) to which is attached. These optical sensors 57 and 58 are the light emitting elements 5
7a and 58a and light receiving elements 57b and 58b.
The optical sensor 57 allows the light emitted from the light emitting element 57a to enter the reflecting surface 51a at an angle of 45 degrees, and the return light reflected by the reflecting surface 51a and the reflecting surface 51b can be received by the light receiving element 57b. So that its position is set. Similarly, in the optical sensor 58, the light emitted from the light emitting element 58a is incident on the reflecting surface 52a at an angle of 45 degrees, and the return light reflected by the reflecting surface 52a and the reflecting surface 52b can be received by the light receiving element 58b. So that its position is set.

Here, the back surfaces of the reflecting surfaces 52a and 52b of the rectangular prism 52 of this example are water-repellent treated surfaces. For example, the surface is coated with a water repellent material. As the water repellent material, a transparent fluorine-based coating material, for example, a fluoroolefin polymer or a fluorine-containing acrylic coating material can be used.

(Detection Operation) Detection of whether or not the ink tank 1 of this example is mounted in the mounting portion of the ink jet printer, and detection of the ink end of the ink tank 1 are performed as follows.

When the ink tank 1 is mounted in the mounting portion of the ink jet printer, as shown in FIG. 4B, the tip portion of the ink supply needle 61 arranged on the side of the ink jet printer ejects the ink from the ink tank 1. Hole 7
The valve 9 located in the ink passage 27 is pushed up by penetrating the through hole 8a of the rubber packing 8 attached to the.

As a result, since the ink take-out hole 7 is opened, the ink absorbed and held in the foam 6 in the main ink chamber 5 of the ink tank 1 is absorbed by the first filter 1.
First, the ink can flow into the ink passage 27 through the sub ink chamber 30, pass through the ink supply needle 61, and can be supplied to the inkjet head on the inkjet printer side. Since such an ink supply mechanism is known, further description will be omitted.

When the ink tank 1 is mounted in this manner, the rectangular prism 51 formed on the side surface of the ink tank 1 faces the optical sensor 57 on the ink jet printer side. Therefore, the light emitted from the optical sensor 57 is
The light is reflected by the reflection surfaces 51a and 51b of the right-angle prism 51 and received by the optical sensor 57, whereby it is detected that the ink tank 1 is attached.

Next, when the ink jet head is driven and ink is ejected, an ink suction force acts on the ink ejection hole 7 by the ink ejection pressure and ink is supplied toward the ink jet head. When the ink is supplied and the amount of the ink retained in the foam 6 is reduced, air is introduced into the main ink chamber 5 through the atmosphere communication port 13 accordingly. As shown by the chain double-dashed line in FIG. 4A, the ink impregnated in the foam 6 gradually decreases as the ink is consumed, and instead, bubbles enter the foam 6. When the amount of ink remaining in the foam 6 becomes small, air enters the sub ink chamber 30 through the first filter 11 to generate bubbles in the sub ink chamber 30. Since the second filter 12 that partitions the space between the sub ink chamber 30 and the side of the ink take-out hole 7 does not allow air bubbles to pass through, the air bubbles gradually accumulate inside the sub ink chamber 30.

When the amount of remaining ink is further reduced, the liquid level of the ink stored in the main ink chamber 5 and the sub ink chamber 30 is gradually lowered, and a pair of prisms of the right-angle prism 52 exposed in the sub ink chamber 30 are provided. Reflective surface 52a, 52b
Is gradually exposed from the ink surface. As a result, the pair of reflecting surfaces 52a and 52b gradually start functioning as reflecting surfaces. When the ink liquid level of the sub ink chamber 30 falls below a predetermined liquid level position (for example, the position L shown in FIG. 5), the light receiving amount of the light receiving element 58b of the optical sensor 58 exceeds the predetermined light receiving amount. Based on the increase in the amount of light received by the light receiving element 58b,
It is detected that the ink in the ink tank 1 is exhausted (ink end).

If the volume of the sub ink chamber 30 is made sufficiently small, the ink end is detected when the remaining ink amount becomes small, so the ink end is detected when the remaining ink amount is as small as possible. It is possible to suppress waste of ink. If this state is regarded as near end and the following processing is performed, waste of ink can be further eliminated. That is, after the near end of ink is detected by the optical sensor 58, the amount of ink used thereafter is counted, and when the value reaches the amount corresponding to the amount of ink stored in the sub ink chamber 30, the real end is set. If confirmed, the ink can be used until the time when the remaining amount of ink is substantially exhausted.

In particular, in this example, the cup-shaped cap 31 is used to form an ink suction mechanism for sucking the ink accumulated in the bottom portion of the sub ink chamber 30 to the position of the second filter 12. Therefore, when the ink amount used is counted from the near end detection of the ink by the optical sensor 58 to perform the real end detection, substantially all the ink accumulated in the sub ink chamber 30 is sucked up, and the ink ejection hole 7 causes the ink jet head to come out. Is supplied to the sub ink chamber 30, the real end of the ink can be detected when the ink is substantially exhausted in the sub ink chamber 30, and the detection accuracy of the real end detection can be improved.

Here, in the ink tank 1 of this example, the back surfaces of the reflecting surfaces 52a and 52b of the rectangular prism 52 are water-repellent treated surfaces. With this configuration, the following operational effects can be obtained.

That is, when air enters the sub ink chamber 30 and bubbles are generated as the remaining ink amount decreases, the space above the ink surface in the sub ink chamber 30 is filled with bubbles. The ink liquid level drops in this state. For this reason, the ink surface is the reflection surface 52.
In a state in which the a and 52b gradually decrease from the upper ends, bubbles are floating near the reflecting surfaces 52a and 52b exposed from the ink surface. Therefore, as shown in FIG. 8B, even if the ink surface becomes lower than the reflection surfaces 52a and 52b, the reflection surfaces 52a and 52b are still retained by the ink held between the air bubbles floating in the vicinity thereof. There is a risk that the back of the car will be covered. In this state, since the reflecting surfaces 52a and 52b do not function as reflecting surfaces, ink end detection cannot be performed.

However, in this example, the water-repellent material 60 is applied to the back surfaces of the reflecting surfaces 52a and 52b, which are the ink interfaces in the sub ink chamber 30 as described above, as shown in FIG. 8 (a). It has a water-repellent surface. Therefore, the bubble B does not adhere to the back surfaces of the reflecting surfaces 52a and 52b. When the bubbles B adhere to the back surfaces of the reflection surfaces 52a and 52b, the bubbles B are bounced off by the water repellency of the reflection surfaces. As a result, when the liquid surface of the ink drops and the reflecting surfaces 52a and 52b are exposed, the reflection state of the reflecting surface changes, and the ink end can be reliably detected.

(Effects of Embodiment) As described above, in the ink tank 1 of this embodiment, the sub ink chamber 30 having a small volume is formed between the main ink chamber 5 and the ink take-out hole 7, and the main ink chamber 5 is formed. The bubbles can be introduced from the side of the sub ink chamber 30 to the side of the ink take-out hole 7 from the sub ink chamber 30, and the back surface of the sub ink chamber 30 is an ink interface. The ink end is detected based on the amount of light reflected by 52a and 52b. Therefore, as compared with the case where the ink end of the ink tank 1 is detected based on the result of counting the number of ink ejections from the ink tank 1 and the ink suction amount by the ink pump,
The ink end can be detected extremely accurately. Therefore, the remaining amount of ink in the ink tank at the time of ink end detection can be reduced, and waste of ink can be suppressed.

Further, in this example, the prism reflecting surface 52a for detecting the ink end, which is exposed in the sub ink chamber 30,
The back surface of 52b is a water-repellent surface. Since the back surfaces of the reflection surfaces 52a and 52b, which are the ink interfaces, are treated to be water-repellent, the back surfaces of the reflection surfaces 52a and 52b are wrapped by the bubbles generated in the sub ink chamber 30, and the ink held between the bubbles is used. It is possible to avoid the adverse effect that the back surfaces of the reflection surfaces 52a and 52b are covered and the reflection state thereof does not change even if the ink liquid level is lowered. Therefore, it is possible to reliably perform the ink end detection with an extremely simple configuration in which the back surfaces of the reflecting surfaces 52a and 52b are subjected to the water repellent treatment.

Next, in this example, the ink passage 27 communicating with the ink outlet 7 is projected inside the sub ink chamber 30 to make the constituent parts for detecting the ink end compact. Therefore, there is an advantage that an increase in the installation space of the ink tank can be suppressed. Further, since the valve 9 and the coil spring 10 that close the ink outlet 7 are arranged in the ink passage 27, the ink outlet can be made compact.

(Modification of Example 1) In this example, the reflecting surface 5
Although the back surfaces of the sub-ink chambers 2a and 52b are subjected to the water repellent treatment, the inner surface portions of the sub ink chambers 30 adjacent to the reflecting surfaces 52a and 52b may be subjected to the water repellent treatment. By doing so, it is possible to more reliably move the bubbles away from the vicinity of the back surfaces of the reflecting surfaces 52a and 52b.

Further, in this example, the cup-shaped cap 31 is attached, but this can be omitted.

Further, when the cup-shaped cap 31 is arranged, it is possible to omit the second filter 12 attached to the communication port 29 of the sub ink chamber 30 and the ink take-out hole 7.

[Embodiment 2] In the above-mentioned Embodiment 1, by applying water repellent treatment to the back surface (ink interface) of the reflecting surface of the rectangular prism, the ink held between the bubbles is kept away from the reflecting surface. This avoids the adverse effect that the reflection surface is covered by. Instead, a member having a surface water repellency is arranged in the sub-ink chamber, the member causes the bubbles in the sub-ink chamber to disappear, and the reflection surface is covered with the ink held between the bubbles. Can be avoided.

FIG. 9 is a schematic view showing an example of an ink tank in which a member having surface water repellency is arranged in the sub ink chamber. Since the main configuration of the ink tank 100 of this example is the same as that of the ink tank 1, the corresponding parts will be denoted by the same reference numerals and detailed description thereof will be omitted.

The ink tank 100 of this example is also provided with the main ink chamber 5, the sub ink chamber 30, the ink take-out hole 7, the atmosphere communication port 13, and the right-angle prism 52 for detecting the ink end. An optical sensor (photo interrupter) 58 for detecting the ink end based on the amount of light reflected from the rectangular prism 52 is provided on the side of the inkjet printer (not shown) in which the ink tank 100 of FIG.

In addition to this, the ink tank 100 of the present example
Then, the member 1 having surface water repellency inside the sub ink chamber 30.
Ten are arranged. The member 1 having surface water repellency of this example
Reference numeral 10 is made of a polytetrafluoroethylene-based sheet or a plate-shaped polypropylene foam and can float in the ink.

Also in the ink tank 100 of this embodiment, when the sub ink chamber 30 is formed between the main ink chamber 5 and the ink take-out hole 7 and the remaining amount of ink in the main ink chamber 5 becomes small, the ink take-out hole 7 is discharged. Each time ink is supplied, air bubbles enter from the main ink chamber 5 to the sub ink chamber 30. When the ink in the main ink chamber 5 is used up, the remaining amount of ink in the ink tank 100 is substantially only the amount of ink stored in the sub ink chamber 30. When the remaining amount of ink in the sub ink chamber 30 becomes small, the back surfaces of the reflecting surfaces 52a and 52b, which are ink interfaces, are exposed from the ink liquid surface S,
The reflection state of the reflecting surfaces 52a and 52b changes. That is, the reflecting surfaces 52a and 52b, which did not function as reflecting surfaces when the back surface was covered with ink, gradually regained their reflecting function as the ink surface S decreased. Therefore, it is possible to detect a state in which the remaining amount of ink is equal to or less than a predetermined amount based on the amount of light reflected by the reflecting surfaces 52a and 52b. Therefore, if the volume of the sub ink chamber 30 is made sufficiently small, the ink end can be detected when the remaining amount of ink is substantially exhausted.

A member 110 having a surface water repellency is arranged inside the sub ink chamber 30. This member 110
Floats on the ink surface S in the sub ink chamber 30, and moves with the ink surface S.

Inside the sub ink chamber 30, when the bubble B filling the space above the ink surface S comes into contact with the surface-repellent member 110, the ink forming the bubble B and having a thin bubble surface is formed. The film of flutters and assembles into larger bubbles. When the bubbles become larger than a certain amount, the interfacial tension of the thin ink film becomes smaller than the internal pressure of the bubbles, and the bubbles burst and disappear. Therefore, the bubble B generated in the sub ink chamber 30 adheres to the back surface of the reflecting surfaces 52a and 52b or floats in the vicinity thereof, and the reflecting surface 52a and 52b is covered with the ink held between the bubbles. The situation can be avoided.

As a result, although the ink surface S in the sub ink chamber 30 is lower than the reflecting surfaces 52a and 52b, the reflecting surfaces 52a and 52b remain covered with the ink held between the bubbles. And the reflecting surface 52a,
It is possible to avoid the adverse effect that the ink end cannot be detected because the reflection state of 52b does not change. It goes without saying that the air-repellent member 110 that floats on the ink liquid surface S has a larger area or is closer to the reflection surfaces 52a and 52b, and thus bubbles are more likely to disappear.

[Other Embodiments] In the first embodiment, the back surfaces of the reflecting surfaces 52a and 52b are subjected to the water repellent treatment, and in the second embodiment, the surface water repellent member 110 is attached to the sub ink chamber 30.
However, it is also possible to adopt a configuration in which both of them are combined.

In each of the above-described embodiments, a pair of orthogonal prism reflecting surfaces are used as the detected portion for detecting the ink end, but, for example, an arc-shaped reflecting surface or another reflecting surface is used. Is also possible.

[0081]

As described above, in the ink tank of the present invention, the main ink chamber containing the foam in which the ink is absorbed and held, and the ink take-out hole for supplying the ink to the ink jet printer side. A sub-ink chamber having a small volume is formed between the sub-ink chamber and the sub-ink chamber so that bubbles can be introduced from the main ink chamber side so that the bubbles do not flow from the sub-ink chamber to the ink extraction hole side. The ink end of the ink tank can be detected by using the reflection surface whose reflection state changes according to the decrease of the ink liquid level in the chamber.

Therefore, the ink end can be detected extremely accurately as compared with the case where the ink end of the ink tank is detected based on the result of counting the number of times ink is ejected from the ink tank and the amount of ink suctioned by the ink pump. Therefore, the remaining amount of ink in the ink tank at the time of ink end detection can be reduced, and waste of ink can be suppressed.

Further, in the present invention, since the back surface (ink interface) of the reflecting surface is subjected to the water repellent treatment, it is possible to keep the bubbles generated inside the sub ink chamber away from the back surface of the reflecting surface, and Can be destroyed by water repellency. Therefore, the back surface of the reflection surface is covered with the ink held between the air bubbles, and even if the ink liquid level drops, the reflection state of the reflection surface does not change, and the ink end detection becomes impossible. It can be avoided. Therefore, it is possible to reliably detect the ink end.

On the other hand, in the present invention, since the member having the surface water repellency is arranged inside the sub-ink chamber, the bubbles generated in the sub-ink chamber become large bubbles while coming into contact with the member and repelling. Together, they eventually disappear. Therefore, the back surface of the reflecting surface is covered with the ink held between the bubbles, and even if the ink liquid level is lowered, the reflection state of the reflecting surface does not change, and it is possible to avoid the problem that the ink end cannot be detected.

Next, the ink jet printer according to the present invention uses the ink tank provided with the detected portion capable of surely displaying the ink end as described above as the ink supply source, so that the ink end of the ink tank is surely reached. It can be detected.

[Brief description of drawings]

1A and 1B are a plan view and a front view showing a foam type ink tank according to a first embodiment of the present invention.

FIG. 2 is a perspective view of the ink tank of FIG. 1 when viewed from the bottom side.

FIG. 3 is an exploded perspective view of the ink tank of FIG.

4A is a cross-sectional view of the ink tank when cut along line IV-IV in FIG. 1, and FIG. 4B is a partial cross-sectional view showing a state in which an ink supply needle is inserted.

5 is a cross-sectional view of the ink tank when cut along the line VV in FIG.

FIG. 6 is a cross-sectional view of the ink tank when cut along line VI-VI in FIG.

FIG. 7 is a diagram showing a cup-shaped cap in the ink tank of FIG.

8A and 8B are explanatory views showing the operation and effect of the ink tank of FIG.

FIG. 9 is a schematic diagram showing an ink tank according to a second embodiment of the present invention.

[Explanation of symbols]

1,100 ink tank 2 container body 3 Upper opening of container body 4 container lid 5 Main ink chamber 6 forms 7 Ink removal hole 8 rubber packing 9 valves 10 coil spring 11 First filter 12 Second filter 13 atmosphere communication hole 21 Bottom plate of container body 27 ink passage 30 Sub ink chamber 31 cap 32 torso 33 Top plate part 36 Protrusion 44 ribs 45 Gap for ink suction 46 Communication 47 Gap 51,52 Prism 51a, 51b, 52a, 52b Reflective surface 57, 58 Optical sensor 57a, 58a light emitting element 57b, 58b Light receiving element 61 Water repellent material 110 Surface water-repellent material S Liquid level in the sub ink chamber B bubbles

Continued front page    (72) Inventor Yukihiro Hanaoka             Seiko, 3-3-3 Yamato, Suwa City, Nagano Prefecture             -In Epson Corporation (72) Inventor Shin Takeuchi             Seiko, 3-3-3 Yamato, Suwa City, Nagano Prefecture             -In Epson Corporation F term (reference) 2C056 EA29 EB20 EB52 KB27 KC01                       KC11 KC13 KC16 KC30

Claims (18)

[Claims] 1. A foam in which ink is absorbed and held, a main ink chamber in which the foam is stored, which is open to the atmosphere, an ink outlet hole, and a space formed between the main ink chamber and the ink outlet hole. In addition, an ink suction force acting on the ink outlet hole allows ink and bubbles to be introduced from the main ink chamber side, and an ink based on the amount of air that has entered the sub ink chamber from the main ink chamber. And a detected portion capable of optically detecting whether or not there is no ink, and the detected portion has a reflection surface whose back surface is an ink interface in the sub-ink chamber, and serves as an ink interface. The ink tank is characterized in that the back surface of the reflecting surface is water-repellent. 2. The ink tank according to claim 1, wherein at least a part of an inner surface of the sub ink chamber adjacent to the back surface of the reflecting surface is a surface that has been subjected to a water repellent treatment. 3. The ink tank according to claim 1, wherein the surface subjected to the water repellent treatment is a surface coated with a water repellent material. 4. The ink tank according to claim 3, wherein the water repellent material is a fluorine-based coating material. 5. The ink tank according to claim 4, wherein the fluorine-based coating material is a fluoroolefin-based polymer or a fluorine-containing acrylic coating material. 6. The ink tank according to claim 1, wherein the reflecting surface is a pair of orthogonal prism reflecting surfaces. 7. The main ink chamber side communication port communicating with the main ink chamber, and the main ink chamber side communication port according to claim 1, wherein the sub ink chamber is attached to the main ink chamber side communication port. And a first filter, wherein the first filter is made of a porous material through which air bubbles can pass by an ink suction force acting on the ink outlet. 8. The discharge hole side communication port communicating with the sub ink chamber and the ink discharge hole, and the second filter attached to the discharge hole side communication port according to claim 7. The ink tank, wherein the second filter is made of a porous material having a pore size smaller than that of the first filter. 9. The ink tank according to claim 1, further comprising a surface water-repellent member arranged in the sub ink chamber. 10. The ink tank according to claim 9, wherein the surface water-repellent member is a polytetrafluoroethylene-based member or a polypropylene-based foam. 11. The ink tank according to claim 9, wherein the surface water-repellent member is arranged in the sub-ink chamber in a state of being able to float above an ink liquid surface. 12. A foam in which ink is absorbed and held, a main ink chamber containing the foam which is open to the atmosphere, an ink outlet hole, and a space formed between the main ink chamber and the ink outlet hole. In addition, an ink suction force acting on the ink outlet hole allows ink and bubbles to be introduced from the main ink chamber side, and an ink based on the amount of air that has entered the sub ink chamber from the main ink chamber. Has a surface to be water-repellent disposed in the sub ink chamber, and the back surface of the detection part is an ink interface in the sub ink chamber. Ink tank with a reflective surface. 13. The ink tank according to claim 12, wherein the surface water-repellent member is a polytetrafluoroethylene-based member or a polypropylene-based foam. 14. The ink tank according to claim 13, wherein the surface water-repellent member is arranged in the sub ink chamber in a state of being able to float above an ink liquid surface. 15. The ink tank according to claim 12, 13 or 14, wherein the reflection surface is a pair of prism reflection surfaces orthogonal to each other. 16. The main ink chamber-side communication port communicating with the main ink chamber, and the main ink chamber-side communication port according to claim 12, wherein the sub-ink chamber is attached to the main ink chamber-side communication port. And a first filter, wherein the first filter is made of a porous material through which air bubbles can pass by an ink suction force acting on the ink outlet. 17. The ejection hole side communication port communicating with the sub ink chamber and the ink ejection hole, and the second filter attached to the ejection hole side communication port. The ink tank, wherein the second filter is made of a porous material having a pore size smaller than that of the first filter. 18. An ink jet printer using the ink tank according to any one of claims 1 to 17 as an ink supply source, and comprising a detection section for detecting the detected section. And inkjet printer.