Ink-jet recording apparatus

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention is mounted on a carriage together with a recording head, includes a sub-tank for supplying ink to the recording head, and is an inkjet type configured to sequentially replenish ink from the main tank to the sub-tank via an ink replenishment tube. Regarding recording equipment.

【0002】

[Conventional technology]

Inkjet recording devices are generally an inkjet recording head mounted on a carriage and moving in the width direction of the recording paper, and a paper feeding means for moving the recording paper in a direction orthogonal to the moving direction of the recording head. Is provided, and recording is performed on the recording paper by ejecting ink droplets from the recording head based on the print data. A recording head capable of ejecting 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 possible by changing the ejection ratio of each ink. ..

【0003】

On the other hand, for example, in this type of recording device provided for office use or business use, it becomes necessary to deploy a large-capacity ink cartridge in order to support a relatively large amount of printing, and for this reason, as an ink cartridge. A recording device is provided in which the main tank is loaded into, for example, a cartridge holder arranged on the main body side of the device.

【0004】

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

【0005】

[Problems to be Solved by the Invention]

By the way, in recent years, there is an increasing demand for a recording device having a long scanning distance, which can print on a large paper surface. In such a recording device, 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 executed, and each sub tank is supplied to the recording head. On the other hand, a configuration that stably supplies ink is required.

【0006】

As one means for satisfying such a function, for example, by pressurizing the ink pack in the main tank with air, an ink flow is generated from the main tank to the sub tank, and the ink is replenished to the sub tank. The configuration that enables it is preferably adopted. In addition, each sub-tank mounted on the carriage adopts a function that can adjust the amount of ink received from the main tank according to the consumption of ink in the recording head, so that each sub-tank is always almost constant. It is possible to store a range of ink.

【0007】

In order to realize such a function, the applicant applies a float member that floats by the ink stored in the sub-tank and a magnetic dose that is attached to the float member and that corresponds to the floating position of the float member. We are proposing an inkjet recording device that has a configuration in which permanent magnets that act on the element are arranged. According to this configuration, ink can be intermittently replenished from the main tank to the sub tank by using the electric output of the magnetron conversion element.

【0008】

However, according to this configuration, there arises a problem that the movement of the float member does not follow the fluctuation of the ink liquid level at least because the magnetic field lines generated by the permanent magnet interfere with the metal body constituting the recording device. .. In particular, in the configuration in which the sub tanks that handle each ink are arranged in parallel, there is a problem that the magnetic field lines of the permanent magnets arranged in each sub tank interfere with each other and the above-mentioned phenomenon greatly occurs. There is a problem that the detection accuracy of the amount of ink in the sub tank is lowered.

【0009】

The present invention has been made based on such a technical viewpoint, and attempts to solve the problem of reducing the detection accuracy of the amount of ink in the sub tank due to the interference of magnetic field lines from the permanent magnets arranged on the float member. It is an object of the present invention to provide an inkjet recording apparatus having improved reliability of ink replenishment operation to a sub tank.

【0010】

[Means for solving problems]

The inkjet recording apparatus according to the present invention, which has been made to achieve the above object, has 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 and mounted on a main tank. An inkjet recording device provided with a sub-tank that supplies ink to the recording head while receiving ink replenishment via an ink replenishment path. The ink is housed in the sub-tank and stored in the sub-tank. A float member that floats by, a permanent magnet that is attached to the float member and causes a magnetic dose corresponding to the floating position of the float member to act on the magnetic-electric conversion element, a back surface of the permanent magnet attached to the float member, and A back yoke is provided to cover each side end surface of the permanent magnet orthogonal to the mounting back surface, and the permanent magnet is attached to the float member via the back yoke.

【0011】

In this case, in the configuration mounted on the carriage so that the plurality of the sub tanks are in a parallel state, particularly corresponding to the different inks ejected from the recording head, a unique action and effect as described later is provided. Can be demonstrated.

【0012】

Then, the surface of the permanent magnet facing the back surface of the permanent magnet attached to the float member is formed to be substantially flush with each other, and the open end of the back yoke covering the side end surface of the permanent magnet is the surface of the permanent magnet. It is desirable that one or the open end of the back yoke is configured to project with respect to the surface of the permanent magnet. In this case, 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 preferably 0.0 to 0.5 mm. Then, as the permanent magnet, one magnetized along the directions of the front surface and the back surface is preferably used.

【0013】

Further, the back yoke can preferably adopt a form in which the back surface and the side end surface of the permanent magnet are covered by drawing. Further, the back yoke can also be configured to cover the back surface and side end surfaces of the permanent magnet by bending.

【0014】

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

【0015】

Then, it is adopted in an inkjet recording device configured so that the valve means arranged in the ink supply path leading from the main tank to the sub tank is controlled by an on-off valve based on the electrical output by the magnetron conversion element described above. Therefore, a preferable effect as described later can be obtained. Further, the main tank described above has an airtight outer shell, is formed in a bag shape by a flexible material, and contains an ink pack in which ink is sealed, and is combined with the outer shell constituent member of the main tank. By adopting it in an inkjet recording device configured so that air pressure is introduced between the ink pack and the ink pack, a preferable effect as described later can be obtained.

【0016】

According to the inkjet recording device having the above configuration, when the ink in the sub tank becomes less than a predetermined value, the position of the float member housed in the sub tank is lowered, and the position of the permanent magnet attached to the float member is lowered. Also moves in the direction of gravity. It is possible to detect that the electric output of the magnetron conversion element represented by the Hall element changes due to the movement of the permanent magnet, and that the position of the float member is lowered by this electric output. In other words, it is possible to detect that the amount of ink in the sub tank has fallen below a predetermined level due to the electrical output of the magnetron conversion element.

【0017】

Therefore, ink can be replenished from the main tank to the sub tank by opening the valve means arranged in the ink replenishment path from the main tank to the sub tank by utilizing the electric output. In this case, an ink pack formed of a flexible material in which ink is enclosed is housed in the main tank, and an air pressure is applied to the space formed by the main tank and the ink pack. Therefore, ink can be quickly replenished from the main tank to the sub tank.

【0018】

When the amount of 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 antigravity direction, and the electricity of the magnetron conversion element is increased by this. With the target output, it is possible to detect a state in which the amount of ink in the sub tank has reached a predetermined amount. Therefore, the amount of ink stored in the sub tank can be appropriately managed by executing the operation of closing the valve means arranged in the ink supply path from the main tank to the sub tank.

【0019】

In this case, a back yoke is prepared to cover the back surface of the permanent magnet attached to the float member and the side end surface of the permanent magnet orthogonal to the attachment back surface, and the permanent magnet is attached to the float member via the back yoke. Therefore, the magnetic flux generated from the permanent magnet can be passed through the magnetically closed circuit formed by the back yoke. This makes it possible to reduce the amount of magnetic flux that tends to bypass the side end face direction of the permanent magnet.

【0020】

Therefore, especially in a recording device having a configuration in which the sub tanks are arranged in parallel, magnetic interference due to the permanent magnets housed in each sub tank can be effectively reduced. As a result, it is possible to avoid the phenomenon that the float member in each sub-tank receives magnetic interference and its position does not follow the fluctuation of the ink liquid level, and the accuracy of detecting the amount of ink stored in each sub-tank is improved. Can contribute to.

【0021】

In this case, the open 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 open end of the back yoke projects with respect to the surface of the permanent magnet. As a result, the magnetic flux that tends to bypass the side end surface direction of the permanent magnet can be effectively guided to the magnetically closed circuit formed by the back yoke, and the above-mentioned effect can be further enhanced.

【0022】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the inkjet recording apparatus according to the present invention will be described based on the embodiment shown in the figure. FIG. 1 is a top view showing an example of an inkjet recording device to which the present invention is applied. In FIG. 1, reference numeral 1 is a carriage, and the carriage 1 is guided by the scanning guide member 4 via the timing belt 3 driven by the carriage motor 2 in the longitudinal direction of the paper feed member 5, that is, in the width direction of the recording paper. It is configured to reciprocate in a certain main scanning direction. Although not shown in FIG. 1, an inkjet recording head 6 described later is mounted on the surface of the carriage 1 facing the paper feed member 5.

【0023】

Further, the carriage 1 is equipped with 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 each ink in order to temporarily store each ink inside the sub tanks 7a to 7d.

【0024】

Then, with respect to the sub tanks 7a to 7d, from each main tank 9a to 9d as an ink cartridge loaded in the cartridge holder 8 arranged at the end of the apparatus main body, each tube 10,10,. Black, yellow, magenta and cyan inks are configured to be replenished via ..... respectively.

【0025】

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

【0026】

The cap member 11a seals the nozzle forming surface of the recording head during the rest period of the recording device, and functions as a lid body for preventing the nozzle opening from drying. Further, although not shown in the figure, one end of the tube in the suction pump (tube pump) is connected to the lower bottom portion of the cap member 11a, and the negative pressure of the suction pump is applied to the recording head to act on the recording head. It is configured to be able to perform a cleaning operation that sucks and discharges ink from the pump.

【0027】

Then, a wiping member 12 in which an elastic material such as rubber is formed in a strip shape is arranged adjacent to the printing area side of the capping means 11, and if necessary, the nozzle forming surface of the recording head is wiped and cleaned. It is configured to be able to.

【0028】

Next, FIG. 2 schematically shows an ink supply system mounted on the recording device shown in FIG. 1, and this ink supply system will be described together with FIG. 1 shown by the same reference numerals. In FIGS. 1 and 2, reference numeral 21 indicates a pressurizing pump, and the air pressurized by the pressurizing pump 21 is supplied to the pressure regulating valve 22, and the pressurized air is pressure-regulated by the pressure regulating valve 22. Each of the above-mentioned main tanks 9a to 9d (representally represented by reference numeral 9 in FIG. 2 and may be simply referred to as reference numeral 9 below) via the pressure detector 23, respectively. It is configured to be supplied.

【0029】

As the schematic configuration of the main tank 9 is shown in FIG. 2, the outer shell is formed in an airtight state, and the ink formed in a bag shape by a flexible material containing ink inside the main tank 9. Pack 24 is stored. The space formed by the main tank 9 and the ink pack 24 constitutes the air chamber 25, and the pressurized air is supplied into the air chamber 25 via the pressure detector 23. ing.

【0030】

With this configuration, each ink pack 24 housed in each main tank 9a to 9d is pressurized by pressurized air, and ink flow is generated from each main tank 9a to 9d to each sub tank 7a to 7d. It is configured to be.

【0031】

The ink pressurized in each of the main tanks 9a to 9d is mounted on the carriage 1 via the first valves 26, 26 ... and the tubes 10, 10, ..., respectively. It is configured to be replenished to each of the sub-tanks 7a to 7d (indicated as reference numeral 7 in FIG. 2 and may be simply referred to as reference numeral 7 in the following).

【0032】

A detailed description of the configuration of the sub tank 7 shown in FIG. 2 will be described later, but the basic configuration thereof is that a float member 31 is arranged inside, and a permanent magnet 32 is attached to a part of the float member 31. There is. The magnetron conversion elements 33a and 33b represented by the Hall element are mounted on the substrate 34 and attached to the side wall of the sub tank 7.

【0033】

With this configuration, electrical output based on the floating position of the float member 31 according to the amount of ink in the sub tank is generated from the Hall elements 33a and 33b. That is, the Hall elements 33a and 33b generate an electric output according to the magnetic dose of the permanent magnet 32 arranged on the float member 31 and the permanent magnet 32 according to the floating position of the float member. ing.

【0034】

With this configuration, for example, when the amount of ink in the sub tank 7 becomes small, the position of the float member 31 housed in the sub tank moves in the direction of gravity, and the position of the permanent magnet 32 also moves in the direction of gravity. Moving. Therefore, the electrical output of the Hall elements 33a and 33b due to the movement of the permanent magnet can be perceived as the amount of ink in the sub tank 7, and the electrical output obtained by the Hall elements 33a and 33b allows the first valve 26 to be detected. Is opened.

【0035】

As a result, the ink pressurized in the main tank 9 is individually delivered to each sub tank 7 in which the amount of ink has decreased. Then, when the amount of ink in the sub tank 7 reaches a predetermined capacity, the first valve 26 is closed based on the electrical output of the Hall elements 33a and 33b. By such repetition, the ink is intermittently replenished from the main tank to the sub tanks, and ink is always stored in a substantially constant range in each sub tank.

【0036】

In this way, each ink pressurized by air pressure in the main tank is replenished to each sub tank based on the electrical output based on the position of each float member arranged in the sub tank. Therefore, the ink replenishment response can be improved, and the amount of ink stored in the sub tank is appropriately managed.

【0037】

Then, 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, and the print data supplied to the recording head 6 is supplied. Based on this, it acts so that ink droplets are ejected from the nozzle opening 6a formed on the nozzle forming surface of the recording head 6. In FIG. 2, reference numeral 11 indicates the capping means described above, and the tube connected to the capping means 11 is connected to a suction pump (not shown).

【0038】

FIG. 3 shows the embodiment of the sub-tank described above in a perspective view, and a part of the constituent members thereof is shown in a cross-sectional state. The sub tank 7 is formed in a substantially rectangular parallelepiped shape, and the whole is flattened. The outer shell of the sub tank 7 is composed of a box-shaped member 41 in which one side wall 41a on the back surface side in FIG. 3 and a peripheral side wall 41b connected to the side wall 41a are integrally formed. , The film member 42 made of a resin material is attached in a sealed state by heat welding means. As a result, the ink storage space 43 is formed inside the box-shaped member 41 and the film-shaped member 42.

【0039】

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

【0040】

The permanent magnet 32 is attached to the free end side of the support arm member 45, and the permanent magnet 32 is used in the horizontal direction in the ink storage space 43 when the support arm member 45 is in a substantially horizontal state. It is configured to be located near the other end of the sub-tank 7, that is, to be closest to the Hall elements 33a and 33b mounted on the substrate 34 attached to the side wall of the sub tank 7.

【0041】

On the other hand, the sub tank 7 is formed with an ink replenishment port 46 at a lower portion in the direction of gravity, that is, at the bottom of the peripheral side wall 41b in this embodiment, and the tube 10 connected to the ink replenishment port 46 is formed. Ink is replenished from the main tank 9 into the ink storage space 43 via the main tank 9.

【0042】

By forming the ink replenishment port 46 in the sub tank 7 in the lower part in the direction of gravity as described above, the ink from the main tank is replenished from the bottom of the ink storage space 43, and therefore, the ink replenishment space replenishes the ink. Care is taken not to cause ink bubbling in 43.

【0043】

Further, in the sub tank 7, a plurality of rib members 47 for reducing the waviness of ink in the sub tank due to the movement of the carriage are arranged in a portion of the float member 31 and the support arm member 45 avoiding the moving region. There is. In this embodiment, the rib member 47 is integrally formed with the side wall 41a as a base so as to project from the side wall 41a of the box-shaped member 41 constituting the sub tank 7 toward the ink storage space 43. The presence of the rib member 47 can reduce the waviness of the ink in the sub tank as described above, thereby improving the accuracy of detecting the amount of ink stored in the sub tank 7 by the Hall element, as will be described in detail later. Can be made to.

【0044】

Further, in the sub tank 7, an ink outlet 48 is formed in the vicinity of the ink supply port 46. A filter member 49 for a foreign matter trap formed in a substantially pentagonal shape (home base shape) is arranged so as to cover the ink outlet 48, and therefore, the ink stored in the sub tank 7 is collected from the filter member 49. It is made to be guided to the ink outlet 48 via. Moreover, since the ink outlet 48 is formed close to the ink replenishment port 46, the relatively new ink introduced into the sub tank 7 acts so as to be immediately ejected from the ink outlet 48.

【0045】

The ink drawn out from the ink outlet 48 is configured to reach the second valve 35 arranged at the lower bottom of the sub tank 7. Then, it is configured to be guided to the connection port 53 of the tube 36 connected to the recording head 6 via the second valve 35.

【0046】

On the other hand, in the upper half of the sub tank 7, a conduction groove 61 conducting to the ink storage space 43 is formed in an inclined state, and at the upper end of the conduction groove 61, that is, at a high place in the gravity direction of the sub tank 7. , An air communication port 62 penetrating the back surface of the side wall 41a of the sub tank 7 is formed. Although not shown in FIG. 3, the atmospheric communication port 62 is blocked by a water-repellent film that allows the air to pass through and blocks the passage of ink. In this way, the atmospheric communication port 62 formed in the sub tank 7 is covered with a water-repellent film. Therefore, when the entire recording device is erroneously turned upside down, for example, the water-repellent film can be used. It is possible to avoid the problem that the ink in the sub tank 7 leaks due to the presence.

【0047】

A recess 41c for positioning the Hall elements 33a and 33b is formed on the side wall of the sub tank 7, and by forming the recess 41c for positioning, the portion of the sub tank 7 is made thinner. , The distance between the moving locus of the permanent magnet 32 attached to the float member 31 and the Hall elements 33a and 33b is configured to be closer. Further, a through hole 63 is formed in a part of the sub tank 7, and the sub tanks are arranged in parallel by one support shaft (not shown) using the through hole 63. It is configured to form a unit.

【0048】

Next, FIG. 4 is a perspective view showing a detailed configuration of the float member 31 arranged in the sub tank 7 described above. The float member 31 according to this embodiment has a box-shaped member 71 in which one side wall and a peripheral side wall connected to the side wall are integrally formed to open the other side surface, and the inside of the float member 31 by closing the opening of the box-shaped member 71. It is composed of a closing member 72 that forms a hollow shape.

【0049】

Further, in the box-shaped member 71, a rib member 71a rising toward the opening thereof is formed in a cross shape. As the closing member 72, for example, a film-shaped member formed of a transparent resin is used, and the film-shaped closing member 72 is attached to the opening peripheral edge of the box-shaped member 71 and the end face of the rib member, for example. It is attached in close contact by heat welding means.

【0050】

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

【0051】

As shown in FIG. 4, the permanent magnets 32 are arranged so that their long sides face in the vertical direction, and by adopting such an arrangement configuration, a plurality of permanent magnets 32 are arranged as described in detail later. When the sub tanks are arranged in parallel, the short sides of the permanent magnets are arranged in the parallel direction of each sub tank, and as a result, the distance between the permanent magnets can be increased as much as possible. As a result, the influence of magnetic interference generated between the permanent magnets can be reduced.

【0052】

As shown in FIG. 4, the permanent magnet 32 and the back yoke 38 are covered with a film-like member 74 attached to the surface thereof, and the ink stored in the sub tank 7 has a chemical adverse effect. It is designed to be avoided.

【0053】

Further, in a part of the float member 31 and the support arm member 45, positioning pins 75 are formed at three places so as to project horizontally on both outer sides thereof. It is desirable that these positioning pins 75 project by 1 mm or more from both side surfaces of the float member 31 and the support arm member 45, whereby a distance of at least 1 mm or more between the float member and the support arm member and the inner wall of the sub tank is maintained. Acts to hold.

【0054】

As a result, it is possible to prevent 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 is hindered by the action of the surface tension. You can solve the problem. In the embodiment shown in the figure, the positioning pin 75 is formed on both the float member 31 and the support arm member 45, but this is formed only on the float member 31 or only on the support arm member 45. In short, it is sufficient that at least the above-mentioned distance is secured between the float member and the inner wall of the sub tank.

【0055】

FIG. 5 shows an enlarged view of the configurations of the permanent magnet 32 and the back yoke 38 described above, and two examples of the back yoke 38 are shown. First, it is desirable that the permanent magnet 32 is formed in a range of 5 to 6 mm on the long side, 2 to 3 mm on the short side, and 1 to 2 mm in thickness. Then, as will be described later, it is magnetized in the central portion in the thickness direction. On the other hand, the back yoke 38 is configured to cover the back surface of the rectangular parallelepiped permanent magnet 32 and the side end faces orthogonal to the back surface. Then, as shown in FIG. 4 described above, the permanent magnet 32 is attached to the float member 31 via the back yoke 38.

【0056】

The back yoke 38 shown in FIG. 5 (A) is configured to cover the back surface and side end surfaces of the permanent magnet 32 by drawing, and the material constituting the back yoke 38 is preferably pure iron or steel. Raw steel is used. These materials have a large relative magnetic permeability and have characteristics that make it difficult for magnetic saturation to occur, and can effectively exert the effect of shielding the magnetic field lines from the permanent magnet 32, which will be described later. Further, the back yoke 38 shown in FIG. 5B is formed by bending, and is also configured to cover the back surface and the side end surface of the permanent magnet 32. Further, also in the back yoke 38 shown in FIG. 5 (B), pure iron or silicon steel is preferably used.

【0057】

Since the back yoke 38 shown in FIG. 5 (B) is formed by bending, some gaps are generated on each of the four sides of the bent portion. Therefore, when the permanent magnet 32 is stored, each ridge line portion in the thickness direction of the permanent magnet 32 is exposed. However, the permanent magnet 32 adopted in this embodiment has the most magnetic lines near the center, the magnetic lines generated from each ridge in the thickness direction are very few, and the magnetic lines generated slightly from the ridges. Is absorbed by the back yoke 38 side by the magnetically closed circuit formed by the back yoke 38. Therefore, even if the back yoke 38 is formed by bending as shown in FIG. 5 (B), the same magnetic shielding effect as that of the configuration shown in FIG. 5 (A) can be exhibited.

【0058】

FIG. 6 shows a state in which the sub-tanks having the above-described configurations are arranged in parallel to form the sub-tank unit, and the Hall element 33 as the magnetron conversion element described above is arranged on the side wall of each sub-tank. Is shown by a schematic diagram. The state shown in FIG. 6 is shown in a cross-sectional view taken along the portion crossing the permanent magnet 32 attached to each sub tank 7.

【0059】

When the sub tanks are arranged in parallel to form the sub tank unit, the through hole 63 formed in the sub tank 7 is used as described with reference to FIG. 3, and each sub tank penetrates through the through hole 63. Each sub-tank is supported in parallel by a single support shaft (not shown) that supports 7.

【0060】

In this way, the sub-tank unit supported in the parallel state is housed in the holder member 81. A substrate holder 82 having an engaging portion 82a that engages with the mounting hole 81a formed in the holder member 81 is provided, and between the substrate holder 82 and the substrate 34 on which the Hall elements 33 are arranged. The Hall element 33 is arranged in a state of being urged on the side wall portion side of the sub tank 7 by a plurality of spring members 83 interposed therein. 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 in the recess 41c for positioning. Placed in the state.

【0061】

FIG. 7 illustrates the action of the permanent magnet 32 mounted on the sub tank and the back yoke 38 in the recording device configured as described above. As shown as a schematic view in FIG. 7, the permanent magnet 32 is magnetized as shown by the north and south poles in the thickness direction. The back yoke 38 accommodating the permanent magnet 32 is configured to cover the back surface (S pole) of the permanent magnet 32 and the side end faces orthogonal to the back surface (S pole), respectively, as described above.

【0062】

Due to the relationship between the permanent magnet 32 and the back yoke 38 having such a configuration, the magnetic field lines F generated from the north pole of the permanent magnet 32 and returning to the south pole are formed toward the open end of the back yoke 38. .. As a result, an S pole is generated at the open end of the back yoke 38. In other words, the back yoke 38 forms a magnetic closed circuit, and the magnetic dose leaking toward the side end of the permanent magnet 32 can be significantly reduced. By this action, when each sub-tank is arranged in parallel to form a sub-tank unit as shown in FIG. 6, the occurrence of magnetic interference by the permanent magnets arranged in each adjacent sub-tank can be effectively reduced. it can.

【0063】

In this case, the surface of the permanent magnet 32 is formed so as to be substantially flush with each other, and the open end of the back yoke 32 is flush with the surface of the permanent magnet, or the open end of the back yoke is of the permanent magnet. It is desirable that the configuration is such that it protrudes from the surface. That is, as shown in FIG. 7, it is desirable that 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 in the range of 0.0 to 0.5 mm.

【0064】

When the nZ is less than 0.0 mm (that is, the surface of the permanent magnet 32 protrudes from the open end of the back yoke 38), it leaks toward the side end of the permanent magnet without passing through the back yoke. The magnetic dose increases, which increases the degree of magnetic interference caused by the permanent magnets placed in each adjacent sub-tank. Further, when the nZ exceeds 0.5 mm, most of the magnetic field lines F generated from the N pole go directly to the open end of the back yoke 38. For this reason, there arises a problem that the magnetic dose exerted on the Hall element facing the N pole of the permanent magnet 32 is reduced and the detection accuracy by the Hall element is lowered.

【0065】

On the other hand, the characteristic curve A shown in FIG. 7 shows the state of the magnetic flux distribution at the 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 shown by the broken line shows the state of the magnetic flux distribution in the permanent magnet alone when the back yoke is not provided. That is, when the back yoke 38 is provided, the magnetic flux distribution is slightly steep as shown in the curve A.

【0066】

Here, assuming that the magnetron 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 done as shown in a. Further, in the case of a permanent magnet without a back yoke, the range of detection sensitivity based on the variation of the Hall element is as shown in b. As can be 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 can contribute to improving the detection accuracy of the amount of ink in the sub tank.

【0067】

Further, in the comparison between the curve A and the curve B shown in FIG. 7, the magnetic flux density at the center of the magnet is larger in the curve A, that is, by providing the back yoke 38, it is possible to increase the magnetic flux density on the surface. Become. This makes it possible to set the magnetic force of the permanent magnet 32 to be smaller than when the back yoke is not provided, and the magnetic dose leaking to the side surface of the permanent magnet 32 is also reduced, so magnetic interference is suppressed more effectively. can do.

【0068】

[Effect of the invention]

As is clear from the above description, according to the inkjet recording apparatus according to the present invention, a back yoke is provided with respect to a permanent magnet attached to a part of a float member housed in a sub tank and moving according to the amount of ink stored. Therefore, especially in a recording device having a configuration in which the sub tanks are arranged in parallel, the phenomenon that the position of the float member does not follow the fluctuation of the ink liquid level due to magnetic interference with each other is avoided. This can contribute to improving the detection accuracy of the amount of ink stored in each sub-tank.

[Simple explanation of drawings]

[Figure 1]

It is a top view which showed the whole structure of the inkjet type recording apparatus to which this invention was applied.

[Figure 2]

It is a schematic diagram which showed the structure of the ink supply system from the main tank to the recording head.

[Fig. 3]

It is a perspective view of the state which the sub tank is seen from one side direction.

[Fig. 4]

It is an exploded perspective view which showed the structure of the float member housed in a sub tank.

[Fig. 5]

It is a perspective view which showed the structure of the permanent magnet and the back yoke attached to a float member.

[Fig. 6]

It is a schematic diagram which showed the form which arranged each sub-tank in a parallel state, and arranged the magnetron conversion element.

[Fig. 7]

It is a schematic diagram considering the relationship between the action of the permanent magnet mounted on the sub-tank and the back yoke, and the accuracy of detecting the amount of ink in the sub-tank.

[Explanation of symbols]

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 replenishment tube (ink replenishment path) 11 Capping means 12 Wiping means 21 Pressurized pump 22 Pressure control valve 23 Pressure detector 24 ink pack 25 air chamber 26 1st valve 31 Float member 32 Permanent magnet 33 (33a, 33b) Hall element (magnetron conversion element) 35 2nd valve 38 back yoke 41 Box-shaped member 41c Positioning recess 42 Film-like member 43 Ink storage space 44 Support shaft 45 Support arm member 71 Box-shaped member 72 Closure member 74 Film-like member 81 Holder member 82 Board holder member