JP2002046292A - Ink jet recording device - Google Patents

Abstract

(57) [Problem] To prevent a phenomenon in which the position of a float member does not follow ink liquid level fluctuation due to mutual magnetic interference. SOLUTION: Ink is supplied to a sub tank 7 mounted on a carriage from an ink cartridge, and ink is supplied from a sub tank 7 to a recording head.
A permanent magnet 32 is attached via a back yoke to a float member 31 which is accommodated in the sub tank and moves in accordance with the amount of stored ink, and a Hall element is provided on a side wall of the sub tank 7 opposed to the permanent magnet 32. 33a, 33b
Is arranged. By providing a back yoke, especially in a recording apparatus having a configuration in which the sub tanks are arranged in parallel with each other, it is possible to avoid a phenomenon that the position of the float member does not follow the ink liquid level fluctuation due to magnetic interference with each other. This can contribute to improving the accuracy of detecting the amount of ink stored in each subtank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided with a sub-tank mounted on a carriage together with a recording head and for supplying ink to the recording head. The sub-tank is successively supplied with ink from a main tank via an ink supply tube. The present invention relates to an ink jet recording apparatus configured as described above.

[0002]

2. Description of the Related Art An ink jet recording apparatus is generally mounted on a carriage and moves in the width direction of the recording paper, and relatively moves the recording paper in a direction perpendicular to the moving direction of the recording head. A paper feed unit for moving the recording paper is provided, and recording is performed on recording paper by discharging ink droplets from a recording head based on print data. A recording head capable of discharging, for example, black, yellow, cyan, and magenta inks is mounted on the carriage, and not only text printing with black ink but also full-color printing is enabled by changing the discharge ratio of each ink. .

On the other hand, in this type of recording apparatus provided for office use or business use, it is necessary to provide a large-capacity ink cartridge in order to handle a relatively large amount of printing. 2. Description of the Related Art A recording apparatus of a type in which a main tank as a cartridge is loaded into, for example, a cartridge holder arranged on a main body side of the apparatus is provided.

A sub-tank is arranged on a carriage on which the recording head is mounted, supplies ink from the main tank to each sub-tank via an ink supply tube, and further supplies ink from each sub-tank to the recording head. It is configured to supply ink.

[0005]

By the way, recently, there is an increasing demand for a recording apparatus which can print on a large paper surface and has a long scanning distance. In such a printing apparatus, in order to improve the throughput, ink is sequentially supplied from the main tank as an ink cartridge to each sub-tank mounted on the carriage while printing is performed, and each sub-tank is supplied to the print head. On the other hand, a configuration that supplies ink stably is required.

As one means for satisfying such a function, for example, an ink flow is generated from the main tank to the sub-tank by pressurizing the ink pack in the main tank with air, and the ink is supplied to the sub-tank. Is preferably adopted.
In addition, in each sub-tank mounted on the carriage, by adopting a function capable of adjusting the amount of ink received from the main tank in accordance with the consumption of ink in the recording head, the sub-tank is always substantially constant. A range of ink can be stored.

In order to realize such a function, the applicant of the present invention has disclosed a float member which floats by ink stored in a sub-tank, and a magnetic force applied to the float member and which corresponds to a floating position of the float member. An ink jet recording apparatus having a configuration in which a permanent magnet that causes a magnetic field to act on a magnetoelectric conversion element is arranged. According to this configuration, the ink can be intermittently supplied from the main tank to the sub-tank by using the electric output of the magnetoelectric conversion element.

However, according to this structure, the line of magnetic force generated by the permanent magnet interferes with the metal body constituting the recording apparatus, and the movement of the float member does not follow the fluctuation of the ink level at least. Occurs. In particular, in a configuration in which the sub-tanks for handling the respective inks are arranged in parallel, there is a problem that the lines of magnetic force of the respective permanent magnets arranged in the respective sub-tanks interfere with each other, and the above-described phenomenon is greatly caused. There is a problem that the accuracy of detecting the ink amount in the sub tank is reduced.

The present invention has been made based on such a technical point of view, and has a problem that the accuracy of detecting the amount of ink in the sub-tank is reduced due to interference of the lines of magnetic force from the permanent magnets arranged on the float member. It is an object of the present invention to provide an ink jet recording apparatus in which the reliability of the operation of supplying ink to the sub tank is improved.

[0010]

In order to achieve the above-mentioned object, an ink jet recording apparatus according to the present invention comprises a recording head mounted on a carriage and reciprocated in the width direction of recording paper; An ink jet recording apparatus mounted on a carriage together with a head and receiving a supply of ink from a main tank via an ink supply path, and a sub tank for supplying ink to the recording head. A float member floating with ink stored in the sub-tank, a permanent magnet attached to the float member, and applying a magnetic force dose to a magnetoelectric conversion element according to a floating position of the float member, and the permanent magnet Of the permanent magnet attached to the float member, and side edges of the permanent magnet orthogonal to the attached back surface And a back yoke for covering each is provided, wherein the permanent magnet is configured to attached to the float member through the back yoke.

In this case, in particular, in a configuration mounted on the carriage such that a plurality of sub-tanks are arranged in parallel with each other corresponding to different inks ejected from the recording head, a unique The function and effect can be exhibited.

The surface of the permanent magnet opposed to the back surface of the permanent magnet attached to the float member is formed to be substantially flush, and the open end of the back yoke covering the side end surface of the permanent magnet is formed by the permanent magnet. It is desirable that the surface be flush with the surface or the open end of the back yoke be protruded from the surface of the permanent magnet. in this case,
Preferably, the distance between the line passing through the surface of the permanent magnet and the line connecting the open end of the back yoke is 0.0 to 0.5 mm.
Is made. Preferably, the permanent magnet is magnetized along the direction of the front surface and the back surface.

[0013] The back yoke may preferably adopt a form in which the back yoke and the side end surface of the permanent magnet are covered by drawing. Further, the back yoke may be configured to cover the back surface and the side end surface of the permanent magnet by bending.

On the other hand, the permanent magnet is formed in a substantially rectangular parallelepiped shape, and in each of the sub-tanks in which a plurality of the sub-tanks are arranged in parallel, the short sides of the permanent magnets are arranged in the parallel direction of the sub-tanks. It is preferable that the long side of each of the permanent magnets is arranged in a direction orthogonal to the parallel direction. In this case, preferably, the long side of the permanent magnet is 5 to 6 mm, and the short side is 2 to 3 m.
m, the thickness is made 1 to 2 mm.

The ink jet recording apparatus is constructed such that the valve means disposed in the ink supply path from the main tank to the sub-tank is controlled to open and close based on the electric output of the magneto-electric conversion element. By adopting such a structure, it is possible to obtain a preferable operation and effect as described below. Further, the main tank has an outer shell configured in an airtight state, is formed in a bag shape from a flexible material, stores an ink pack in which ink is sealed inside, and includes an outer constituent member of the main tank. By adopting the present invention in an ink jet recording apparatus configured so that air pressure is introduced between the ink pack and the ink pack, it is possible to obtain the following advantageous effects.

According to the ink jet recording apparatus having the above configuration, when the ink in the sub-tank becomes equal to or less than a predetermined value, the position of the float member accommodated in the sub-tank is lowered, and the permanent member attached to the float member is lowered. The position of the magnet also moves in the direction of gravity. Due to the movement of the permanent magnet, the electrical output of the magneto-electric conversion element represented by the Hall element changes, and it is possible to sense that the position of the float member has been lowered by the electrical output. In other words, the fact that the ink in the sub-tank has become equal to or less than a predetermined value can be sensed by the electrical output of the magnetoelectric conversion element.

Therefore, by using the electric output and opening the valve means disposed in the ink supply path from the main tank to the sub tank, ink can be supplied from the main tank to the sub tank. In this case, a configuration in which an ink pack formed of a flexible material in which ink is sealed is housed in the main tank, and air pressure is applied in a space formed by the main tank and the ink pack is used in combination. Thus, ink can be quickly supplied from the main tank to the sub tank.

When the ink in the sub-tank reaches a predetermined amount due to the supply of ink to the sub-tank,
The position of the permanent magnet attached to the float member moves in the anti-gravity direction, and the state where the ink in the sub-tank reaches a predetermined amount can be detected based on the electric output of the magneto-electric conversion element. Therefore, by executing the operation of closing the valve means disposed in the ink supply path from the main tank to the sub tank, the amount of stored ink in the sub tank can be appropriately managed.

In this case, a back yoke is provided to cover the back surface of the permanent magnet attached to the float member and a side end surface of the permanent magnet orthogonal to the attached back surface, and the permanent magnet is attached to the float member via the back yoke. With this configuration, the magnetic flux generated from the permanent magnet can pass through the magnetic closed circuit formed by the back yoke. Thereby, the amount of magnetic flux that tries to bypass the side end surface direction of the permanent magnet can be reduced.

Therefore, especially in a recording apparatus having a configuration in which the sub-tanks are arranged in parallel with each other, it is possible to effectively reduce the magnetic interference caused by the permanent magnets housed in the respective sub-tanks. Thereby, it is possible to avoid a phenomenon that the float member in each sub-tank receives magnetic interference and its position does not follow the ink level fluctuation, thereby improving the detection accuracy of the amount of stored ink in each sub-tank. Can contribute to

In this case, the opening end of the back yoke covering the side end surface of the permanent magnet is flush with the surface of the permanent magnet, or the opening end of the back yoke projects from the surface of the permanent magnet. As a result, it is possible to effectively guide the magnetic flux that attempts to bypass the side end face direction of the permanent magnet to the magnetic closed circuit formed by the back yoke,
The above effects can be further enhanced.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an ink jet recording apparatus according to the present invention will be described based on an embodiment shown in the drawings. FIG. 1 is a top view showing an example of an ink jet recording apparatus to which the present invention is applied. In FIG. 1, reference numeral 1 denotes a carriage. The carriage 1 is guided by a scanning guide member 4 via a timing belt 3 driven by a carriage motor 2 in a longitudinal direction of a paper feeding member 5, that is, in a width direction of the recording paper. It is configured to reciprocate in a certain main scanning direction. Then, although not shown in FIG.
An ink jet recording head 6 described later is mounted on a surface facing the paper feed member 5.

The carriage 1 has sub-tanks 7a to 7d for supplying ink to the recording head. In this embodiment, four sub-tanks 7a to 7d are provided corresponding to the respective inks in order to temporarily store the respective inks therein.

Then, the cartridge holder 8 disposed at the end of the apparatus main body with respect to the sub tanks 7a to 7d.
From each of the main tanks 9a to 9d as ink cartridges loaded in
Are configured to be supplied with black, yellow, magenta, and cyan inks via 0, 10,..., Respectively.

On the other hand, in a non-printing area (home position) on the moving path of the carriage 1, a capping means 11 capable of sealing the nozzle forming surface of the recording head is arranged. A cap member 11a formed of a flexible material such as rubber capable of sealing the nozzle forming surface of the recording head is provided on the upper surface of the capping means 11.
Is arranged. Then, when the carriage 1 moves to the home position, the capping means 11 rises following the movement, and the nozzle forming surface of the recording head can be sealed by the cap member 11a. .

The cap member 11a seals the nozzle forming surface of the recording head during the idle period of the recording apparatus,
It functions as a lid that prevents drying of the nozzle openings. Although not shown in the drawing, one end of a tube of a suction pump (tube pump) is connected to the lower bottom of the cap member 11a, and a negative pressure from the suction pump is applied to the recording head, thereby causing the recording head to operate. It is configured such that a cleaning operation of sucking and discharging ink from the printer can be executed.

A wiping member 12 formed of a strip of elastic material such as rubber is disposed adjacent to the printing area side of the capping means 11, and wipes the nozzle forming surface of the recording head as required. It is configured so that it can be cleaned.

Next, FIG. 2 schematically shows an ink supply system mounted on the recording apparatus shown in FIG. 1, and this ink supply system will be described together with FIG. . 1 and 2, reference numeral 21 denotes a pressurizing pump. Air pressurized by the pressurizing pump 21 is supplied to a pressure adjusting valve 22, and pressurized air adjusted by the pressure adjusting valve 22. Are provided via the pressure detector 23 to each of the main tanks 9a to 9d described above (represented by the numeral 9 in FIG. 2 as a representative, and may be simply represented by the numeral 9 in the following). It is configured to be supplied.

As shown in FIG. 2, the main tank 9 has an outer periphery formed in an air-tight state, and a bag-like interior made of a flexible material filled with ink. The stored ink pack 24 is stored.
The space formed by the main tank 9 and the ink pack 24 forms an air chamber 25.
It is configured such that pressurized air is supplied to the inside through a pressure detector 23.

With this configuration, each of the main tanks 9a to 9
Each of the ink packs 24 stored in d is pressurized by pressurized air, and is configured to generate an ink flow from each of the main tanks 9a to 9d to each of the sub tanks 7a to 7d.

The ink pressurized in the main tanks 9a to 9d is supplied to first valves 26, 26, respectively.
And each of the sub-tanks 7a to 7d mounted on the carriage 1 via the tubes 10, 10,... (Represented by the numeral 7 in FIG. 2 as a representative, and hereinafter, simply represented by the numeral 7). In some cases.).

Although a detailed description of the structure of the sub tank 7 shown in FIG. 2 will be described later, its basic structure is that a float member 31 is disposed inside, and the float member 31
A permanent magnet 32 is attached to a part of. Then, the magneto-electric conversion elements 33a, 33 represented by Hall elements
b is mounted on the substrate 34 and is attached to the side wall of the sub tank 7.

With this configuration, an electrical output based on the floating position of the float member 31 according to the amount of ink in the sub-tank is generated by the Hall elements 33a and 33b. That is, according to the permanent magnet 32 arranged on the float member 31 and the magnetic force dose by the permanent magnet 32 according to the floating position of the float member, the Hall element 3
An electrical output is generated by 3a and 33b.

With this configuration, for example, when the amount of ink in the sub-tank 7 decreases, the position of the float member 31 stored in the sub-tank moves in the direction of gravity, and accordingly, the position of the permanent magnet 32 also changes. Move in the direction of gravity. Therefore, the Hall element 33 due to the movement of the permanent magnet
a, 33b can be sensed as the amount of ink in the sub-tank 7, and the Hall elements 33a, 33b
The first valve 2 is provided by the electrical output obtained by
6 is opened.

As a result, the ink pressurized in the main tank 9 is individually sent into each of the sub-tanks 7 in which the amount of ink has been reduced. Then, when the ink amount in the sub tank 7 reaches a predetermined capacity,
The first valve 26 is closed based on the electric outputs of the Hall elements 33a and 33b. By such repetition, the ink acts to intermittently replenish the ink from the main tank to the sub-tank, and each sub-tank always stores a substantially constant range of ink.

As described above, each ink pressurized in the main tank by air pressure is supplied to each sub-tank based on the electric output based on the position of each float member arranged in the sub-tank. Since it is configured to be replenished, the replenishment response of ink can be improved, and the amount of stored ink in the sub-tank is appropriately managed.

The ink is supplied from each sub-tank 7 to the recording head 6 via the second valve 35 and the tube 36 connected to the second valve 35. The ink is supplied to the recording head 6. Based on the print data, it acts so that ink droplets are ejected from the nozzle openings 6a formed on the nozzle forming surface of the recording head 6. In FIG. 2, reference numeral 11 denotes the above-described capping means, and the tube connected to the capping means 11 is connected to a suction pump (not shown).

FIG. 3 is a perspective view showing an embodiment of the above-described sub-tank, and a part of its constituent members is shown in a sectional state. The sub-tank 7 is formed in a substantially rectangular parallelepiped shape, and is entirely flat. The outer periphery of the sub-tank 7 is a box-shaped member 4 in which a side wall 41a on the back side in FIG. 3 and a peripheral side wall 41b connected thereto are integrally formed.
A film member 42 made of a resin material is hermetically attached to the periphery of the opening of the box-shaped member 41 by means of heat welding. Thus, an ink storage space 43 is formed inside the box-shaped member 41 and the film-shaped member 42.

A support shaft 44 projecting from the one side wall 41a on the back side of the box-shaped member 41 toward the ink storage space 43 is formed integrally with the box-shaped member 41.
The float member 31 is arranged so as to be movable in the direction of gravity in the ink storage space 43 around the support shaft 44 as a rotation center. In this embodiment, the support shaft 44 is disposed near the horizontal end of the ink storage space 43, and the float member 31 is supported by the support shaft 44 that is movable about the support shaft 44 as a rotation center. The arm member 45 is formed integrally with the movable free end side.

The permanent magnet 32 is attached to the free end side of the support arm member 45. When the support arm member 45 is substantially horizontal, the permanent magnet 32 is attached to the ink storage space 43. , That is, the Hall elements 33a, 33 mounted on the substrate 34 attached to the side wall of the sub-tank 7,
3b.

On the other hand, the sub-tank 7 has a lower portion in the direction of gravity, that is, in this embodiment, the peripheral side wall 4.
An ink supply port 46 is formed at the bottom of 1b, and ink is supplied from the main tank 9 into the ink storage space 43 through the tube 10 connected to the ink supply port 46. I have.

The ink supply port 46 in the sub tank 7
Is formed in the lower part in the direction of gravity as described above, so that the ink from the main tank can be stored in the ink storage space 4.
The ink is supplied from the bottom of the ink storage space 43 so as not to cause bubbling of the ink in the ink storage space 43 due to the supply of the ink.

Further, in the sub-tank 7, a plurality of rib members 47 for reducing the waving of the ink in the sub-tank due to the movement of the carriage are provided in a portion avoiding the movement region of the float member 31 and the support arm member 45. Are located. In this embodiment, the rib member 47 is formed integrally with the side wall 41a as a base so as to protrude toward the ink storage space 43 from the side wall 41a of the box-shaped member 41 constituting the sub tank 7. Due to the presence of the rib member 47, the ripple of the ink in the sub-tank can be reduced as described above, and as described later in detail, the accuracy of detecting the amount of ink stored in the sub-tank 7 by the Hall element is improved. Can be done.

Further, an ink outlet 48 is formed in the sub-tank 7 near the ink supply port 46. A filter member 49 for trapping foreign matter, which is formed in a substantially pentagonal (home base) shape, is disposed so as to cover the ink outlet port 48. Therefore, the ink stored in the sub tank 7 is filtered by the filter member 49. Through the ink outlet 48. In addition, since the ink outlet port 48 is formed near the ink supply port 46, a relatively new ink introduced into the sub tank 7 acts so as to be immediately drawn out from the outlet port 48.

The ink led out from the ink outlet 48 is configured to reach the second valve 35 disposed at the lower bottom of the sub-tank 7. The tube 3 connected to the recording head 6 via the second valve 35
6 is connected to the connection port 53.

On the other hand, in the upper half of the sub-tank 7, a conductive groove 61 for conducting to the ink storage space 43 is formed in an inclined state, and the upper end of the conductive groove 61, that is, the high position of the sub-tank 7 in the direction of gravity. In the part, the side wall 41 of the sub tank 7
An air communication port 62 that penetrates through the back surface in FIG. Although not shown in FIG. 3, the air communication port 62 is closed by a water-repellent film that allows the air to pass therethrough and prevents the ink from passing therethrough. As described above, the air communication port 62 formed in the sub tank 7 is configured to be covered with the water repellent film. Therefore, when the entire recording apparatus is erroneously turned upside down, for example, the water repellent film is formed. The problem that the ink in the sub-tank 7 leaks due to the presence can be avoided.

A concave portion 41c for positioning the Hall elements 33a and 33b is formed on the side wall of the sub-tank 7. By forming the concave portion 41c for this positioning, the portion of the sub-tank 7 becomes thinner. In this state, the movement trajectory of the permanent magnet 32 attached to the float member 31 and the distance between the Hall elements 33a and 33b can be made closer. Further, a through hole 63 is formed in a part of the sub tank 7, and the sub tanks are arranged in a side-by-side state by one supporting shaft (not shown) using the through hole 63. The unit is configured to be formed.

Next, FIG. 4 is a perspective view showing a detailed configuration of the float member 31 disposed in the sub tank 7 described above. A float member 31 according to the present embodiment has a box-shaped member 71 in which one side wall and a peripheral side wall connected thereto are integrally formed and the other side surface is opened, and the opening of the box-shaped member 71 is closed to close the inside. And a closing member 72 forming a hollow shape.

The box-shaped member 71 has a cross-shaped rib member 71a which rises toward its opening. As the closing member 72, a film-shaped member formed of, for example, a transparent resin is used, and the film-shaped closing member 72 is, for example, with respect to the opening periphery of the box-shaped member 71 and the end surface of the rib member. They are attached in close contact by means of heat welding.

The float member 31 thus formed
The support shaft 4 formed on the sub tank 7 as described above
The support arm member 45, which is movable about the rotation center 4, is integrally formed on the movable free end side. A support ring 73 is formed integrally with the base end of the support arm member 45 and is supported around the support shaft 44 as a center of rotation. The permanent magnet 32 formed in a rectangular parallelepiped shape is attached to the free end side of the support arm member 45 via the back yoke 38 described later in detail.

As shown in FIG. 4, the permanent magnet 32 is disposed so that its long side is oriented vertically.
By employing such an arrangement, as will be described in detail later, when a plurality of sub-tanks are respectively arranged in a parallel state, the short sides of the respective permanent magnets are arranged in the parallel direction of the respective sub-tanks, The distance between the permanent magnets is set to be large even if it is slightly small. Thereby, the influence of magnetic interference generated between the permanent magnets can be reduced.

The permanent magnet 32 and the back yoke 38 are covered with a film-like member 74 adhered to the surface thereof as shown in FIG. Adverse effects are avoided.

Further, positioning pins 75 are formed at three portions on both the float member 31 and the support arm member 45 so as to protrude horizontally on both outer sides thereof. These positioning pins 75 are attached to the float member 3
1 and the supporting arm member 45 preferably protrude 1 mm or more from both side surfaces, so that at least 1 m between the float member and the supporting arm member and the inner wall of the sub tank.
It acts to maintain a distance of at least m.

Thus, it is possible to prevent the occurrence of ink accumulation due to the surface tension of the ink between the float member 31 and the support arm member 45 and the inner wall of the sub-tank 7, and the movement of the float member 31 by the action of the surface tension. The problem of inhibition can be solved. In the embodiment shown in the drawings, the positioning pin 75 is formed on both the float member 31 and the support arm member 45.
5 may be formed only, in short, it is sufficient that at least the distance described above is secured between the float member and the inner wall of the sub tank.

FIG. 5 is an enlarged view of the configuration of the permanent magnet 32 and the back yoke 38. Two examples of the back yoke 38 are shown. First, the permanent magnet 32 has a long side of 5 to 6 mm and a short side of 2 to 3 m
m, and the thickness is desirably formed in the range of 1 to 2 mm. And it is magnetized in the central part in the thickness direction as described later. On the other hand, the back yoke 38 is configured to cover the back surface of the permanent magnet 32 formed in a rectangular parallelepiped shape and the side end surface orthogonal to the back surface. Then, the permanent magnet 32 is attached to the float member 31 via the back yoke 38 as shown in FIG.

The back yoke 38 shown in FIG.
The back yoke 38 is preferably made of pure iron or silicon steel as a material constituting the back yoke 38 by drawing. These materials have high relative magnetic permeability and are hard to be magnetically saturated.
The effect of shielding the lines of magnetic force from 2 can be effectively exhibited. Further, the back yoke 38 shown in FIG.
Is formed by bending, and is also configured to cover the back surface and the side end surface of the permanent magnet 32 similarly.
And also in the back yoke 38 shown in FIG. 5B, pure iron or silicon steel is preferably used.

The back yoke 38 shown in FIG.
Due to the shape formed by the bending process, some gaps are generated on each of the four sides of the bent portion. Therefore, when the permanent magnet 32 is stored, each ridge portion in the thickness direction of the permanent magnet 32 is exposed. However, the permanent magnet 32 employed in this embodiment
In the vicinity of the center, the lines of magnetic force are the largest, the lines of magnetic force generated from each ridge in the thickness direction are very small, and the lines of magnetic force generated slightly from the ridge are reduced by the magnetic closed circuit formed by the back yoke 38. It is absorbed by the back yoke 38 side. Accordingly, the back yoke 38 is
FIG. 5 shows that even if it is formed by bending as shown in FIG.
The same magnetic shielding effect as the configuration shown in FIG.

FIG. 6 shows a state in which the sub-tanks having the above-described configuration are arranged in parallel to form a sub-tank unit.
FIG. 3 is a schematic diagram showing a configuration in which No. 3 is disposed on a side wall of each sub-tank. In addition, the state shown in FIG. 6 is shown in a cross-sectional view broken at a portion crossing the permanent magnet 32 attached to each sub-tank 7.

When the sub-tanks are arranged in parallel to form a sub-tank unit, the through-holes 63 formed in the sub-tank 7 are used as described with reference to FIG. Each sub-tank is supported in parallel by a single support shaft (not shown) that supports each sub-tank 7.

The sub-tank units supported in parallel in this manner are housed in the holder member 81. A substrate holder 8 having an engaging portion 82a that engages with a mounting hole 81a formed in the holder member 81.
The Hall element 33 is urged toward the side wall of the sub-tank 7 by a plurality of spring members 83 interposed between the substrate holder 82 and the substrate 34 on which the Hall elements 33 are arranged. It is arranged in a state. In this case, as described with reference to FIG. 3, a recess 41c for positioning the Hall element 33 is formed on the side wall of the sub tank 7, and the Hall element 33 is fitted into the recess 41c for positioning. It is arranged in a state.

FIG. 7 illustrates the operation of the permanent magnet 32 and the back yoke 38 mounted on the sub-tank in the recording apparatus configured as described above. As shown schematically in FIG. 7, the permanent magnet 32
It is magnetized as indicated by the pole and the south pole. And
The back yoke 38 for accommodating the permanent magnet 32 is configured to cover the back surface (S-pole) of the permanent magnet 32 and the side end surface orthogonal to the back surface (S-pole) as described above.

In the relationship between the permanent magnet 32 and the back yoke 38 having such a structure, the magnetic force lines F generated from the N pole of the permanent magnet 32 and returning to the S pole are directed toward the open end of the back yoke 38. It is formed. Thus, an S pole is generated at the opening end of the back yoke 38. In other words, a magnetic closed circuit is formed by the back yoke 38, and the amount of magnetic force leaking toward the side end of the permanent magnet 32 can be significantly reduced. By this operation, when the sub tanks are arranged in a parallel state as shown in FIG. 6 to form a sub tank unit, it is possible to effectively reduce the occurrence of magnetic interference by the permanent magnets arranged in the adjacent sub tanks. it can.

In this case, the surface of the permanent magnet 32 is
The back yoke 32 is formed so as to be substantially flush with the surface of the permanent magnet, or the open end of the back yoke projects from the surface of the permanent magnet. Is desirable. That is, as shown in FIG. 7, the distance nZ between the line passing through the surface of the permanent magnet 32 and the line connecting the open end of the back yoke is 0.0 to 0.5 m.
m.

The nZ is less than 0.0 mm (ie,
In the case where the surface of the permanent magnet 32 protrudes from the opening end of the back yoke 38), the amount of magnetic force leaking toward the side end of the permanent magnet without passing through the back yoke is increased, and thereby the adjacent magnets are adjacent to each other. The degree of occurrence of magnetic interference by the permanent magnets arranged in each sub tank increases. Further, when the nZ exceeds 0.5 mm, most of the magnetic lines of force F generated from the N pole are directly transferred to the back yoke 3.
8 toward the open end. For this reason, there arises a problem that a magnetic force dose applied to the Hall element facing the N pole of the permanent magnet 32 is reduced, and the detection accuracy by the Hall element is reduced.

On the other hand, a characteristic curve A shown in FIG. 7 shows a state of a magnetic flux distribution at a position facing the N pole of the permanent magnet 32 provided with the back yoke 38 (for example, the arrangement position of the Hall element). The characteristic curve B indicated by the broken line
Shows the state of the magnetic flux distribution in the permanent magnet alone without the back yoke. That is, when the back yoke 38 is provided, the magnetic flux distribution is slightly sharpened as shown by the curve A.

Here, assuming that the magnetoelectric conversion sensitivity due to the variation of the Hall element is in the range of L1 and L2 shown in FIG. 7, when the back yoke 38 is provided,
The variation of the detection width based on the variation of the Hall element is a
Is performed as shown in FIG. In the case of a single permanent magnet without a back yoke, the range of the detection sensitivity based on the variation of the Hall element is as shown in b. As understood from this characteristic, when the back yoke is provided, the variation in the detection width due to the variation in the Hall element can be substantially reduced. In other words, it is possible to contribute to improving the detection accuracy of the ink amount in the sub tank.

In the comparison between the curves A and B shown in FIG. 7, the magnetic flux density at the center of the magnet is higher in the curve A, that is, by providing the back yoke 38, the magnetic flux density on the surface is increased. Becomes possible. As a result, the magnetic force of the permanent magnet 32 can be set smaller than when no back yoke is provided, and the amount of magnetic force leaking in the lateral direction of the permanent magnet 32 is reduced, so that magnetic interference is more effectively suppressed. can do.

[0068]

As is apparent from the above description, according to the ink jet recording apparatus of the present invention, the permanent magnet attached to a part of the float member which is accommodated in the sub-tank and moves according to the amount of stored ink. In particular, in a recording apparatus in which sub-tanks are arranged in parallel with each other, the position of the float member follows magnetic ink interference, and the position of the float member follows the fluctuation of the ink liquid level. It is possible to avoid the phenomenon of not being performed, and to contribute to improving the detection accuracy of the amount of stored ink in each subtank.

[Brief description of the drawings]

FIG. 1 is a plan view showing an overall configuration of an ink jet recording apparatus to which the present invention is applied.

FIG. 2 is a schematic diagram illustrating a configuration of an ink supply system from a main tank to a recording head.

FIG. 3 is a perspective view of a state where the sub tank is viewed from one surface direction.

FIG. 4 is an exploded perspective view showing a configuration of a float member housed in a sub tank.

FIG. 5 is a perspective view showing a configuration of a permanent magnet and a back yoke attached to the float member.

FIG. 6 is a schematic diagram showing a mode in which sub-tanks are arranged in parallel and a magnetoelectric conversion element is provided.

FIG. 7 is a schematic diagram that considers the relationship between the operation of a permanent magnet and a back yoke mounted on a sub-tank and the accuracy of detecting the amount of ink in the sub-tank.

[Explanation of symbols]

Reference Signs List 1 carriage 6 recording head 6a nozzle opening 7 (7a, 7b, 7c, 7d) sub-tank 8 cartridge holder 9 (9a, 9b, 9c, 9d) main tank (ink cartridge) 10 ink supply tube (ink supply path) 11 capping means DESCRIPTION OF SYMBOLS 12 Wiping means 21 Pressurizing pump 22 Pressure regulating valve 23 Pressure detector 24 Ink pack 25 Air chamber 26 First valve 31 Float member 32 Permanent magnet 33 (33a, 33b) Hall element (magnetoelectric conversion element) 35 Second valve 38 Back Yoke 41 Box-shaped member 41c Positioning recess 42 Film-shaped member 43 Ink storage space 44 Support shaft 45 Support arm member 71 Box-shaped member 72 Closing member 74 Film-shaped member 81 Holder member 82 Substrate holder member

Claims (11)

[Claims] A recording head mounted on a carriage and reciprocated in the width direction of the recording paper; and a recording head mounted on the carriage together with the recording head to receive ink supply from a main tank via an ink supply path. An ink jet recording apparatus comprising: a sub-tank for supplying ink to a recording head, wherein the float member is housed in the sub-tank, and floats with the ink stored in the sub-tank, and is attached to the float member. A permanent magnet for applying a magnetic force dose corresponding to the floating position of the float member to the magnetoelectric conversion element; a back for covering the back surface of the permanent magnet attached to the float member and a side end face of the permanent magnet orthogonal to the attached back surface, respectively. A yoke, wherein the permanent magnet flows through the back yoke. An ink jet recording apparatus comprising attached to member. 2. The ink jet recording apparatus according to claim 1, wherein a plurality of said sub-tanks are mounted on said carriage so as to be in parallel with each other for each of different inks ejected from a recording head. . 3. The permanent magnet is formed such that the surface of the permanent magnet facing the back surface of the permanent magnet attached to the float member is substantially flush, and the open end of the back yoke covering the side end surface of the permanent magnet is formed of the permanent magnet. The ink jet recording apparatus according to claim 1 or 2, wherein the surface of the back yoke is flush with the surface or the opening end of the back yoke is protruded from the surface of the permanent magnet. 4. An interval between a line passing through the surface of the permanent magnet and a line connecting an open end of the back yoke is 0.0 to 0.5.
4. The ink jet recording apparatus according to claim 3, wherein the diameter is set to mm. 5. The ink jet recording apparatus according to claim 3, wherein the permanent magnet is magnetized along the direction of the front surface and the back surface. 6. The ink jet recording apparatus according to claim 1, wherein the back yoke is configured to cover a back surface and side end surfaces of the permanent magnet by drawing. 7. The ink jet recording apparatus according to claim 1, wherein the back yoke is configured to cover a back surface and side end surfaces of the permanent magnet by bending. 8. The sub-tank, wherein the permanent magnet is formed in a substantially rectangular parallelepiped shape, and in each of the sub-tanks in which a plurality of the sub-tanks are arranged in parallel, short sides of the respective permanent magnets are arranged in a parallel direction of the sub-tanks. 8. The ink jet recording apparatus according to claim 2, wherein a long side of each of the permanent magnets is arranged in a direction orthogonal to the parallel direction. 9. The long side of the permanent magnet is 5 to 6 m.
9. The ink jet recording apparatus according to claim 8, wherein m, the short side is 2-3 mm, and the thickness is 1-2 mm. 10. A valve means disposed in an ink supply path from a main tank to a sub-tank is controlled to open and close based on an electric output of the magnetoelectric conversion element. An ink jet recording apparatus according to any one of the above. 11. An outer shell structure of the main tank, wherein an outer shell of the main tank is formed in an airtight state, the main tank is formed in a bag shape from a flexible material, and an ink pack filled with ink is housed inside. The ink jet recording apparatus according to any one of claims 1 to 10, wherein air pressure is introduced between the member and the ink pack.