JP2006062248A - Liquid storage tank and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid storage tank which detects a clearance between a fixed wall portion and a movable wall portion corresponding to a change in the remaining quantity of a liquid in the liquid storage tank as a variation in the inductance of a coil by making electricity flow through a coil through a pair of terminals from the outside, and permits the keeping track of the remaining quantity of the liquid in the liquid storage tank irrespective of the kind of the liquid and an image forming device. <P>SOLUTION: The liquid storage tank 17 to store liquids to be supplied to the outside in an enclosed condition has a fixed wall portion 38, a supply port 41 formed in the fixed wall portion 38 and to supply the liquids to the outside, the movable wall portion 39 that displaces with respect to the fixed wall portion 38 in accordance with the remaining quantity of the liquids, an elastically deformable coil 31, both ends of which are linked to the movable wall portion 39 and the fixed wall portion 38 in a manner that makes the inductance vary with the displacement of the movable wall portion 39 and formed of an electric conductor, and a pair of terminals 43a and 43b provided in the fixed wall portion 38, and connected to both ends of the coil to detect a variation in the inductance from the outside. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid storage tank capable of detecting the remaining amount of stored liquid from the outside, and an image forming apparatus for forming an image on a print medium using the liquid supplied from the liquid storage tank.

  The “print” described in this specification is not only for forming significant information such as characters and figures, but also manifested so that it can be perceived visually by humans, regardless of significance. Regardless of whether or not it is, it includes a case where an image, a pattern, a pattern or the like is widely formed on the print medium, or the print medium is processed such as etching.

  The “print medium” is a sheet-like object that can accept not only a piece of paper used in a general printing apparatus but also a liquid such as a cloth, a resin film, a metal plate, glass, ceramics, wood, and leather. Other three-dimensional solids such as a sphere and a cylinder are also included.

  Furthermore, “liquid” is to be interpreted widely as the definition of “print” above, and by being applied on the print medium, the formation of images, patterns, patterns, etc., processing of the print medium such as etching, Alternatively, it refers to a liquid that can be subjected to ink processing, such as solidification or insolubilization of the colorant in the ink applied to the print medium, and includes any liquid used for printing.

  As an image forming apparatus that forms an image on a print medium using ink, an ink jet print apparatus that uses an ink jet head capable of ejecting ink and forms an image on the surface of the print medium by applying ink to the print medium is known. ing. This ink jet printing apparatus has a relatively low noise during printing and can form small dots with high density, and is used for many prints including color prints in recent years. As one form of such an ink jet printing apparatus, one using an ink jet head (hereinafter referred to as a print head) in which an ink tank for storing ink is connected inseparably or detachably is known. In such a printing apparatus, it comprises means for transporting the print medium in a first direction, and means for scanning a carriage on which the print head is mounted in a second direction intersecting the first direction, In the process of scanning and moving the carriage in the second direction, ink is ejected from the print head to form an image on the print medium. Furthermore, by mounting a plurality of print heads that discharge yellow, cyan, and magenta color inks in addition to black ink on the carriage, not only single-color printing of text images with black ink, but also the color ink discharge rate can be reduced. Full color printing is also possible by changing and mixing colors.

  In the ink jet printing apparatus, the remaining amount of ink in the ink tank is detected and displayed, a warning is issued when the remaining ink amount is low, and the printing operation is also stopped. . This is because it is possible to reliably prevent printing defects that occur when printing is performed in the absence of ink, and the waste of print media associated therewith. In particular, when a print head using thermal energy generating means such as an electrothermal conversion element is used as the ink discharging means in the print head, the ink is produced using the pressure generated by the change in the state of the ink to which the thermal energy is applied. It will be discharged. For this reason, if the thermal energy generating means is driven in the absence of ink, the print head itself may be damaged due to the temperature rise of the print head. To prevent this, the user is prompted to replace the ink tank. Is also extremely important.

  Conventionally, as a method for detecting the absence of ink in an ink tank, a light-transmitting state of the ink tank that changes according to the remaining amount of ink is detected using an optical element, or according to the liquid level of the ink. The so-called sensor type is generally used to detect a changing electrical continuity using a pair of electrodes arranged in the interior of the ink tank, but the ink ejection pulse ejected from the print head A dot count method is also known in which the number of ink is counted and the amount of ink used is added to estimate the remaining ink amount. As another method, there is an ink capacity detection method as disclosed in Patent Document 1. In this ink capacity detection method, an ink chamber having a diaphragm and a core that is displaced according to the remaining amount of ink is provided in the middle of the ink supply path that connects the ink tank and the print head, and a coil that surrounds the ink chamber is disposed. The remaining amount of ink is detected based on the change in the position of the core inside the coil. In addition, the ink capacity detection device disclosed in Patent Document 2 has a coil wound around the ink supply path connecting the ink tank and the print head or around the ink tank, and changes depending on the amount of ink inside the coil. The remaining amount of ink is detected based on the inductance of the coil.

JP-A-7-125251 JP-A-10-217508

  In a sensor system using an optical element, an electrode member, or the like, in order to detect the remaining amount of ink in the ink tank in stages, it is necessary to add the number of parts, which causes a problem of increasing manufacturing costs. Also, it is difficult to detect the remaining amount of ink in multiple steps, and it is generally difficult to detect the remaining amount of ink, and it is generally necessary to replace the ink tank. Only the liquid level is detected.

  In the dot count method that counts the number of ink ejection pulses, the remaining amount of ink is estimated including variations in the amount of ink used by the print head to form dots. Considering the tolerance of the amount of ink initially stored in the tank, it becomes extremely difficult to accurately detect the ink end point.

  On the other hand, in the case of the ink capacity detection method disclosed in Patent Document 1, since it is necessary to form a large ink chamber, for a carriage in which a relatively small capacity ink tank is mounted in a replaceable manner, It is difficult to provide an ink chamber integrally. In particular, when a plurality of ink tanks are mounted on the carriage for color printing, it is necessary to provide ink chambers corresponding to the respective ink tanks, and the enlargement of the carriage cannot be avoided, resulting in an increase in cost. End up.

  As disclosed in Patent Document 2, when a coil is wound around the ink supply path, the remaining amount of ink cannot be detected in stages, and only the ink level at the end of ink is detected. Become. When the coil is wound around the ink tank, it is possible to detect the remaining amount of ink linearly to some extent, but since the ink is located only inside the coil, the normal ink other than the magnetic ink is used. With the type of ink, the magnetic flux in the vicinity of the coil is greatly reduced, the change in inductance is reduced, and the detection accuracy is deteriorated.

  An object of the present invention is to provide a liquid storage tank capable of highly accurately detecting the remaining amount of liquid stored therein even with a general liquid having no special properties such as magnetism. Another object of the present invention is to provide an image forming apparatus on which the liquid storage tank is mounted.

  A first aspect of the present invention is a liquid storage tank for storing a liquid supplied to the outside in a sealed state, and is provided with a fixed wall and a liquid formed on the fixed wall for supplying the liquid to the outside. A movable wall portion that is displaced according to the remaining amount of liquid with respect to the supply port, the fixed wall portion, and the movable wall portion and the fixed wall portion so that the inductance changes in accordance with the displacement of the movable wall portion. And a pair of terminals connected to both ends of the coil to detect a change in inductance from the outside. And has.

  In the present invention, the movable wall portion is displaced with respect to the fixed wall portion in accordance with a change in the remaining amount of the liquid stored in the liquid storage tank. By causing electricity to flow from the outside to the coil via the pair of terminals of the liquid storage tank, the inductance of the coil changes with a change in the distance between the fixed wall portion and the movable wall portion, that is, a change in the length of the coil. The remaining amount of liquid in the liquid storage tank is estimated according to the change in inductance.

  In the liquid storage tank according to the first aspect of the present invention, the coil may have an elastic force that urges the movable wall portion so that the liquid storage tank tends to have a negative pressure.

  According to a second aspect of the present invention, there is provided a tank mounting portion on which the liquid storage tank according to the first embodiment of the present invention is replaceably mounted, and the liquid supplied from the liquid storage tank mounted on the tank mounting portion. An image forming apparatus that forms an image on a print medium using a liquid discharge head that discharges liquid, and a pair of connection terminals that are formed on the tank mounting portion and are electrically connected to a pair of terminals of the liquid storage tank, And a liquid remaining amount detecting means for detecting the remaining amount of liquid in the liquid storage tank based on a change in inductance of the coil.

  Also in the present invention, the movable wall portion is displaced with respect to the fixed wall portion in accordance with a change in the remaining amount of the liquid stored in the liquid storage tank. By flowing electricity from the outside to the pair of terminals at both ends of the coil of the liquid storage tank via the pair of connection terminals of the tank mounting portion, the change in the distance between the fixed wall portion and the movable wall portion, that is, With the change, the inductance of the coil changes. The remaining amount of liquid in the liquid storage tank is estimated according to the change in inductance.

  According to a third aspect of the present invention, a tank holder in which the liquid storage tank according to the first aspect of the present invention is replaceably mounted, and liquid supplied from the liquid storage tank mounted on the tank holder is discharged. A head cartridge having a liquid discharge head and a pair of intermediate terminals formed on the tank holder and connected to a pair of terminals of the liquid storage tank to detect a change in inductance from the outside is detachably mounted. An image forming apparatus that includes a cartridge mounting portion and forms an image by discharging liquid from the liquid discharge head onto a print medium, and is formed on the cartridge mounting portion and is electrically connected to a pair of intermediate terminals of the head cartridge. And a pair of connection terminals connected to the pair of connection terminals based on a change in inductance of the coil. Is characterized in that comprises a liquid residual amount detection means for detecting the remaining amount of liquid in the liquid storage tank Te.

  Also in the present invention, the movable wall portion is displaced with respect to the fixed wall portion in accordance with a change in the remaining amount of the liquid stored in the liquid storage tank. By flowing electricity from the outside to the pair of terminals at both ends of the coil of the liquid storage tank via the pair of connection terminals of the cartridge mounting portion and the intermediate terminal of the head cartridge, a change in the interval between the fixed wall portion and the movable wall portion, That is, as the coil length changes, the coil inductance changes. The remaining amount of liquid in the liquid storage tank is estimated according to the change in inductance.

  In the image forming apparatus according to the second or third aspect of the present invention, the liquid remaining amount detecting means may have an oscillation control circuit whose oscillation frequency changes according to the inductance of the coil.

  According to the liquid storage tank of the present invention, a fixed wall portion, a supply port formed on the fixed wall portion for supplying liquid to the outside, and a movable wall that is displaced according to the remaining amount of liquid with respect to the fixed wall portion. A wall, an elastically deformable coil formed of a conductor, both ends of which are connected to the movable wall and the fixed wall so that the inductance changes in accordance with the displacement of the movable wall, and the fixed wall Provided with a pair of terminals that are connected to both ends of the coil and detect changes in inductance from the outside. The distance between the movable wall part and the fixed wall part according to the change in the remaining amount of liquid in the storage tank can be detected as a change in coil inductance, and the liquid in the liquid storage tank can be detected regardless of the type of liquid. The remaining amount is positive It is possible to grasp.

  When the coil has an elastic force that biases the movable wall so that the liquid storage tank tends to have a negative pressure, the liquid storage tank can always be kept in a negative pressure state, and the liquid in the liquid storage tank can evaporate. Can be prevented more reliably.

  An image is formed on a print medium using a liquid discharge head for discharging a liquid supplied from a liquid storage tank mounted on the tank mounting portion. According to the image forming apparatus of the present invention, a pair of connection terminals formed on the tank mounting portion and conducted to the pair of terminals of the liquid storage tank, and coupled to the pair of connection terminals to change the inductance of the coil. And a liquid remaining amount detecting means for detecting the remaining amount of liquid in the liquid storage tank on the basis of the electric current from the pair of connection terminals of the tank mounting portion to the coil via the pair of terminals of the liquid storage tank. Therefore, the distance between the movable wall part and the fixed wall part corresponding to the change in the remaining amount of liquid in the liquid storage tank Out it is possible to, irrespective of the whether the type of liquid, it is possible to accurately grasp the remaining amount of liquid in the liquid storage tank.

  A tank holder in which a liquid storage tank according to the present invention is replaceably mounted, a liquid discharge head for discharging liquid supplied from the liquid storage tank mounted on the tank holder, a tank holder, and a liquid storage tank formed on the tank holder. A cartridge mounting portion on which a head cartridge having a pair of intermediate terminals connected to a pair of terminals and detecting a change in inductance from the outside is detachably mounted is provided, and liquid is discharged from the liquid discharge head onto the print medium. According to the image forming apparatus of the present invention for forming an image, a pair of connection terminals formed on the cartridge mounting portion and conducted to the pair of intermediate terminals of the head cartridge, and the coil connected to the pair of connection terminals Remaining liquid level detection that detects the remaining liquid level in the liquid storage tank based on changes in inductance Therefore, by supplying electricity from the pair of connection terminals of the cartridge mounting section to the pair of terminals at both ends of the coil of the liquid storage tank via the intermediate terminal of the head cartridge, the liquid in the liquid storage tank The distance between the movable wall and the fixed wall according to the change in the remaining amount can be detected as a change in the inductance of the coil, and the remaining amount of liquid in the liquid storage tank can be accurately determined regardless of the type of liquid. It is possible to grasp.

  When the liquid remaining amount detecting means has an oscillation control circuit in which the oscillation frequency changes according to the inductance of the coil, the change in the inductance of the coil can be regarded as a change in the frequency of the pulse.

  Embodiments in which the image forming apparatus according to the present invention is applied to a serial scan type ink jet printer will be described in detail with reference to FIGS. 1 to 9. However, the present invention is not limited to these embodiments, and All changes and modifications encompassed within the scope of the inventive concept described in the scope are possible, and can of course be applied to other techniques belonging to the spirit of the invention. For example, it can also be used to detect the remaining amount of various liquids (chemical liquid, drinking water, etc.) other than ink.

  FIG. 1 schematically shows the appearance of the ink jet printer in this embodiment, and FIG. 2 shows the control block. That is, both ends of a pair of guide shafts 12 extending in parallel to each other are fixedly supported on the housing 11, and a carriage 13 is slidable along the longitudinal direction of the guide shaft 12 on these guide shafts 12. It is attached. The carriage 13 scans and moves in a first direction along the longitudinal direction of the guide shaft 12 by a carriage scanning drive unit incorporating a carriage scanning motor 14 (not shown). A head cartridge 16 integrally provided with a print head 15 (see FIG. 3) is detachably mounted on the carriage 13, and an ink tank 17 for storing ink to be supplied to the print head 15 is attached to the head cartridge 16. And is detachably mounted.

  The platen 19 that supports the print medium 18 extends along the scanning movement direction of the carriage 13 so as to face the print head 15 of the head cartridge 16 mounted on the carriage 13. A transport roller 20 for the print medium 18 is rotatably provided on the end side. By operating the medium transport motor 21 (see FIG. 2) connected to the transport roller 20, the transport roller 20 is driven and rotated, and the print medium 18 is fed from the paper supply port 22 provided at the front end of the housing 11. It is drawn into the housing 11, its transport direction is reversed, and it is transported onto the platen 19 so as to be orthogonal to the scanning movement direction of the carriage 13. By alternately combining the intermittent transport movement of the print medium 18 and the scanning movement of the head cartridge 16 mounted on the carriage 13, a predetermined image is formed on the print medium 18 by the ink ejected from the print head 15. It is supposed to be formed.

  The print head 15 may use thermal energy generated from the electrothermal transducer as energy for ejecting ink. In this case, film boiling occurs in the ink due to the heat generated by the electrothermal converter, and the ink can be ejected from the ejection port by the foaming energy at that time. In addition, the ink ejection method in the print head 15 is not limited to the type using film boiling using such an electrothermal transducer, and for example, the type in which ink is ejected using a piezoelectric element. It is also possible to adopt one.

  On one scanning movement end side of the carriage 13, a discharge recovery device 23 is provided for maintaining a good discharge state of ink from a discharge port (not shown) formed in the print head 15. No. 23 is a cap (not shown) that covers the discharge port surface 24 (see FIG. 3) where the discharge port of the print head 15 opens in a sealed state, and the inside of the cap has a negative pressure, and the viscosity increases from the discharge port of the print head 15. A suction pump (not shown) that can suck and discharge ink and the like is included. In addition to image formation, a preliminary ejection operation is also possible in which ink is ejected from the ejection port of the print head 15 in a capped state.

  The CPU 25 that executes control processing, data processing, and the like of the operation of the inkjet printer 10 includes a ROM 26 that stores programs such as these processing procedures, and a RAM 27 that is used as a work area for executing these processes. Connected. The operation of the print head 15 is controlled by the CPU 25 via the head driver 28. More specifically, the CPU 25 gives drive data to the electrothermal transducer of the print head 15, that is, image data and a drive control signal, that is, a heat pulse signal, to the head driver 28 to control ink ejection. Similarly, the operation of the carriage scanning motor 14 and the medium transporting motor 21 is controlled by the CPU 25 via motor drivers 29 and 30, respectively. In addition, a detection coil 31 (described later) arranged in an ink tank 17 (described later) is connected to the CPU 25 via an ink remaining amount detection unit 32, and the ink remaining amount detection unit 32 is based on the inductance of the detection coil 31. The remaining amount of ink in the ink tank 17 is detected. The CPU 25 can issue a display or warning for prompting the user to replace the ink tank 17 based on the detection result in the ink remaining amount detection unit 32.

  The internal structure of the head cartridge 16 in this embodiment is schematically shown in FIG. That is, the head cartridge 16 has a tank holder 33 on which the ink tank 17 is mounted, the print head 15, and an ink supply path that communicates between the print head 15 and the ink tank 17 mounted on the tank holder 33. The ink tank 17 in the present embodiment is replaceable with respect to the tank holder 33, but may be configured integrally with the tank holder 33. Similarly, the ink supply unit 34 in the present embodiment in which the filter 35 is incorporated is also integrated with the print head 15 and the tank holder 33, but a configuration that can be separated from these is adopted. Alternatively, it may be provided integrally with the carriage 13 together with the print head 15 to form an ink supply path from the ink tank 17 to the print head 15 when the ink tank 17 is mounted on the carriage 13. The tank holder 33 is formed with an intermediate terminal 36 that is electrically connected to a connection terminal (not shown) formed on the carriage 13. The connection terminal is connected to the ink remaining amount detection unit 32 and the head driver 28 described above via a flexible cable (not shown).

  The ink tank 17 in this embodiment includes a fixed wall portion 38 and a movable wall portion 39 that define an ink storage chamber 37 that is substantially sealed except for a connection portion with the ink supply portion 34. The ink storage chamber 37 stores ink to be discharged from the print head 15, and the ink is supplied to the print head 15 through the ink supply unit 34 in accordance with the ink discharge operation of the print head 15. It has become. The movable wall portion 39 that defines the ink storage chamber 37 together with the fixed wall portion 38 that can be regarded as a rigid body in a state where ink is stored is formed in a pyramid shape with a thin sheet material having flexibility. In the present embodiment, since the movable wall portion 39 is exposed to atmospheric pressure, the inside of the ink storage chamber 37 is basically regulated to be substantially equal to atmospheric pressure.

  The fixed wall portion 38 of the ink tank 17 is surrounded by a lower wall portion 38a that is in contact with the tank holder 33 and a movable wall portion 39 having a pyramid shape around the upper wall portion, and is opposed to the lower wall portion 38a substantially in parallel. 38b, and the upper wall 38b can be moved up and down in the direction facing the lower wall 38a with the deformation of the movable wall 39 according to the amount of ink in the ink storage chamber 37. When the upper wall portion 38b is displaced in a direction opposite to the lower wall portion 38a, the movable wall portion 39 surrounding the upper wall portion 38b is stretched and deformed, and the upper wall portion 38b is maintained in a substantially parallel state with the lower wall portion 38a. By taking this into consideration, there is no adverse effect caused by a sudden change in the internal pressure of the ink in the ink storage chamber 37 due to the deformation of the movable wall portion 39.

  The connection between the print head 15 of the head cartridge 16 and the ink tank 17 is made by inserting an ink introduction part 40 constituting a part of the ink supply part 34 into the ink tank 17. Thereby, the print head 15 and the ink tank 17 are fluidly coupled, and ink can be supplied from the ink tank 17 to the print head 15. An elastically deformable seal member 42 such as rubber is attached to the ink supply port 41 of the ink tank 17 into which the ink introduction part 40 is inserted. The seal member 42 is in close contact with the periphery of the ink introducing portion 40 to prevent ink leakage from the ink tank 17 and to ensure the connection between the ink introducing portion 40 and the ink tank 17. For this reason, in the ink tank 17 in the present embodiment, the ink consumption progresses from the initial state where the ink storage chamber 37 is sufficiently filled with ink, and the ink in the ink storage chamber 37 gradually decreases, so that the ink storage chamber 37 Even if the volume of the ink tank 37 tends to decrease or the surrounding environment of the ink tank 17 changes, for example, the outside air temperature rises or depressurizes, the intrusion of outside air into the ink storage chamber 37 can be prevented. The problem that ink leaks from the ejection port of the print head 15 does not occur.

  Between the lower wall portion 38a and the upper wall portion 38b of the ink storage chamber 37, the detection coil 31 in the form of a compression coil spring containing a spring force that biases the upper wall portion 38b away from the lower wall portion 38a. Is intervening. The spring force of the detection coil 31 generates a negative pressure in a range that allows the print head 15 to perform an ink discharge operation in balance with the holding force of the ink meniscus formed at the discharge port of the print head 15. The state shown in FIG. 3 shows a state in which the volume of the ink storage chamber 37 is maximized. Even in this state, the upper wall 38 b is biased by the spring force from the detection coil 31, and the ink storage chamber 37 has the inside. Is maintained in an appropriate negative pressure state.

  The inner side of the detection coil 31 is formed of a conductor such as a metal, and the surface portion in contact with the ink is covered with an electrical insulating film such as a resin. As this electrical insulating film, a material that does not elute as an impurity in the ink stored in the ink tank 17, for example, a high-purity polypropylene or polyethylene with very few additives is preferable. A conductive member 45a connected to one of a pair of terminals 43a and 43b formed on the outer surface of the ink tank 17 through the flexible lead wire 44 is connected to the upper wall 38b side of the detection coil 31, The conductive member 45a is fixed to the inner wall of the upper wall portion 38b. The conductive member 45b connected to the other of the pair of terminals 43a and 43b is also connected to the lower wall portion 38a side of the detection coil 31. The conductive member 45b is connected to the lower wall portion so as to penetrate the fixed wall portion 38. It is fixed to 38a. The pair of terminals 43 a and 43 b are in electrical contact with the intermediate terminal 36 provided on the head carriage 13 when the ink tank 17 is mounted on the tank holder 33.

  Accordingly, in the state where the ink tank 17 is attached to the tank holder 33 of the head cartridge 16 attached to the carriage 13 and the ink introduction part 40 of the ink supply part 34 is inserted into the ink tank 17, the detection coil 31. The pair of conductive members 45 a and 45 b, the flexible lead wire 44, the terminals 43 a and 43 b, the intermediate terminal 36, and the connection terminal connected to both ends in the longitudinal direction are electrically connected and connected to the ink remaining amount detection unit 32.

  FIG. 4 schematically shows a circuit configuration of the remaining ink amount detection unit 32 in the present embodiment. That is, the detection coil 31 functions as a coil inductance having the ink in the ink tank 17 as a core, and corresponds to the length of the detection coil 31 that changes in accordance with the displacement of the upper wall portion 38b, that is, the ink storage chamber 37. The inductance changes according to the remaining ink amount. The detection coil 31 is shortened and shortened as the upper wall 38b is pulled downward in FIG. 3 as ink is consumed, and the inductance changes as the number of turns per unit length increases. Thus, the remaining amount of ink can be reliably detected. In the present embodiment, the NAND gate 46, the resistor R, and the pair of capacitors C1 and C2 constitute an oscillation control circuit whose oscillation frequency changes according to the inductance of the detection coil 31. When the gate input “H” is input to the NAND gate 46, the NAND gate 46 functions as an inverter, and the oscillation control circuit oscillates at a frequency corresponding to the inductance of the detection coil 31. When the gate input “L” is input to the NAND gate 46, the oscillation control circuit does not function.

  FIG. 4 shows a cross-sectional structure of the ink tank 17 in a state where the ink in the ink storage chamber 37 is almost completely consumed. As the volume of the ink storage chamber 37 decreases, the upper wall portion 38b approaches the lower wall portion 38a against the spring force of the detection coil 31, and the detection coil 31 is gradually compressed. As a result, the inductance of the detection coil 31 gradually increases. The ink remaining amount detection unit 32 grasps the ink remaining amount in the ink tank 17 by using a principle that the inductance of the detection coil 31 itself is larger as the total length of the detection coil 31 whose number of turns does not change is shorter.

  The relationship between the amount of ink used, that is, the amount consumed, and the inductance of the detection coil 31 is shown in FIG. The ink remaining amount detection unit 32 uses an oscillation control circuit as shown in FIG. 4 to detect a change in inductance of the detection coil 31 as a change in pulse frequency, and detects the remaining amount of ink in the ink tank 17.

  In the present embodiment, the detection coil 31 is connected to the ink remaining amount detection unit 32 via the terminals 43 a and 43 b of the ink tank 17, the intermediate terminal 36 of the head cartridge 16, and the connection terminal of the carriage 13. . For this reason, by mounting the ink tank 17 on the head cartridge 16 and mounting the head cartridge 16 on the carriage 13, the detection coil 31 is electrically connected to the ink remaining amount detection unit 32. For this reason, the ink remaining amount detection unit 32 can also detect the mounting state of the ink tank 17 and the head cartridge 16.

  In the embodiment described above, the movable wall portion 39 of the ink tank 17 is exposed to the outside, and the movable wall portion 39 is deformed as the ink stored in the ink storage chamber 37 is consumed, so that the upper wall portion of the fixed wall portion 38 is deformed. Although it has been made possible to visually recognize the displacement of 38b, it is also possible to make the structure invisible from the outside.

  The internal structure of another embodiment in which the liquid storage tank according to the present invention is applied to the above-described ink tank 17 is schematically shown in FIG. 7 together with the head cartridge 16. Elements having the same functions as those of the previous embodiment are shown in FIG. The same reference numerals are used, and duplicate descriptions are omitted. That is, the ink tank 17 in the present embodiment includes the cover wall portion 47 that is integrated with the lower wall portion 38a of the fixed wall portion 38 so as to cover the movable wall portion 39 and the upper wall portion 38b of the fixed wall portion 38. . The cover wall 47 can be regarded as a rigid body together with the lower wall 38a. The detection coil 31 is interposed between the cover wall portion 47 and the upper wall portion 38b. For this reason, the pair of conductive members 45a and 45b conducting to the detection coil 31 is outside the ink storage chamber 37, and the detection coil 31 and the ink can be brought into a non-contact state. The space inside the cover wall portion 47 is in an air communication state via an air communication hole 48 formed in the cover wall portion 47. In this embodiment, the terminal 43b connected to the conductive member 45b fixed to the cover wall portion 47 does not contact the intermediate terminal 36 of the tank holder 33, and directly conducts to a connection terminal (not shown) formed on the carriage 13. It is like that.

  The detection coil 31 in the present embodiment has a form of a tension coil spring, and includes a spring force that brings the upper wall portion 38b closer to the cover wall portion 47 even when the volume of the ink storage chamber 37 is substantially maximum. Thus, an appropriate negative pressure is applied to the ink in the ink storage chamber 37.

  FIG. 8 shows a cross-sectional structure of the ink tank 17 in a state where the ink in the ink storage chamber 37 is almost completely consumed. As the volume of the ink storage chamber 37 decreases, the upper wall portion 38b approaches the lower wall portion 38a against the spring force of the detection coil 31, and the detection coil 31 is gradually stretched. As a result, the inductance of the detection coil 31 gradually decreases.

  FIG. 9 shows the relationship between the amount of ink used, that is, the amount consumed and the inductance of the detection coil 31 in this embodiment. The remaining ink amount detection unit 32 detects the remaining ink amount in the ink tank 17 by using the oscillation control circuit as shown in FIG.

  The detection coil 31 need not be set in the vertical direction, but can also be set in the horizontal direction because of the orientation of the ink tank 17 and the like. In short, it is only necessary to adopt a configuration in which the volume of the ink tank 17 changes according to the remaining amount of ink in the ink tank 17 and the entire length of the detection coil 31 changes accordingly. In addition to the method of detecting the inductance of the detection coil 31 as a change in the transmission frequency as described above, other appropriate methods can be appropriately employed. In this case, any method that can electrically detect at least the inductance of the detection coil 31 may be used. Further, a part of the ink remaining amount detection unit 32 can be incorporated on the ink tank 17 side.

  The present invention includes an ink jet system that includes means (for example, an electrothermal converter or a laser beam) that generates thermal energy as energy used for discharging a liquid, and causes a change in the state of the liquid by the thermal energy. In the head cartridge or the image forming apparatus, an excellent effect is brought about. This is because according to such a method, high density and high definition of the print can be achieved.

  The present invention can also be effectively applied to a full-line type liquid discharge head having a length corresponding to the maximum width of a print medium that can be printed by the image forming apparatus. As such a liquid discharge head, either a configuration satisfying the length by a combination of a plurality of liquid discharge heads or a configuration as a single liquid discharge head formed integrally may be used.

  Even in the serial type as in the above-described embodiments, the liquid discharge head fixed integrally with the carriage that is moved by scanning, or the electrical connection with the carriage by being exchangeably attached to the carriage. This is also possible when using a replaceable chip-in type head cartridge that can supply liquid from the main body of the apparatus, or a head cartridge in which a liquid storage head itself has a tank that stores liquid in an integrated or replaceable manner. The invention is effective.

  As the configuration of the image forming apparatus of the present invention, it is possible to further stabilize the effect of the present invention by adding a recovery means for making the liquid discharge state from the liquid discharge head appropriate, a preliminary auxiliary means, etc. It is preferable. Specifically, a capping unit, a cleaning unit, a pressurizing or sucking unit for the liquid discharge head, a preheating unit for heating using an electrothermal converter, a heating element different from this, or a combination thereof, A preliminary discharge unit that discharges separately from the printing operation can be given.

  Regarding the types and the number of liquid discharge heads to be mounted, for example, only one corresponding to a single color ink is provided, and a plurality of liquid discharge heads corresponding to a plurality of types of inks having different hues and densities (lightness) are provided. It may be provided individually. That is, for example, the print mode of the image forming apparatus is not limited to a print mode of only a mainstream color such as black, but the liquid discharge head may be configured integrally or a plurality of combinations. The present invention is also very effective for an image forming apparatus having at least one of full-color print modes using color or mixed colors. In this case, it is also effective to discharge a processing liquid (printability improving liquid) for adjusting the printability of ink according to the type of print medium and the print mode from a dedicated or common liquid discharge head to the print medium.

  As the form of the image forming apparatus according to the present invention, in addition to what is used as an output terminal of information processing equipment such as a computer or an optical disk apparatus, a copying apparatus combined with a reader, a facsimile apparatus or a textile printing apparatus having a transmission / reception function, Alternatively, it may be in the form of an etching apparatus, and the print medium may be a sheet or long paper or fabric, or a plate-like wood or leather, stone, resin, glass, metal, etc. A three-dimensional solid structure etc. can be mentioned.

FIG. 3 is a three-dimensional projection diagram schematically illustrating an appearance of an embodiment in which the image forming apparatus according to the present invention is applied to a serial type ink jet printer. FIG. 2 is a control block diagram of the ink jet printer shown in FIG. 1. FIG. 2 is a cross-sectional view schematically showing an internal structure of a head cartridge mounted on the ink jet printer shown in FIG. 1. FIG. 2 is a circuit diagram of an ink remaining amount detection unit for the ink tank shown in FIG. 1. FIG. 4 is a cross-sectional view schematically showing a state in which ink has run out in the head cartridge shown in FIG. 3. 6 is a graph schematically showing the relationship between the ink consumption in the ink tank and the inductance of the detection coil in the head cartridge shown in FIGS. 3 and 5. FIG. FIG. 2 is a cross-sectional view schematically showing the internal structure of an embodiment in which the liquid storage tank according to the present invention is applied to a head cartridge mounted on the ink jet printer shown in FIG. 1. FIG. 8 is a cross-sectional view schematically illustrating a state in which ink has run out in the head cartridge illustrated in FIG. 7. 9 is a graph schematically showing the relationship between the ink consumption in the ink tank and the inductance of the detection coil in the head cartridge shown in FIGS.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inkjet printer 11 Housing 12 Guide shaft 13 Carriage 14 Carriage scanning motor 15 Print head 16 Head cartridge 17 Ink tank 18 Print medium 19 Platen 20 Conveyance roller 21 Medium conveyance motor 22 Paper supply port 23 Discharge recovery device 24 Discharge port surface 25 CPU
26 ROM
27 RAM
28 Head drivers 29, 30 Motor driver 31 Detection coil 32 Ink remaining amount detection part 33 Tank holder 34 Ink supply part 35 Filter 36 Intermediate terminal 37 Ink storage chamber 38 Fixed wall part 38a Lower wall part 38b Upper wall part 39 Movable wall part 40 Ink introduction portion 41 Ink supply port 42 Seal member 43a, 43b Terminal 44 Flexible lead wire 45a, 45b Conductive member 46 NAND gate 47 Cover wall portion 48 Air communication hole R Resistance C1, C2 Capacitor

Claims (5)

A liquid storage tank for storing liquid supplied to the outside in a sealed state,
A fixed wall,
A liquid supply port formed in the fixed wall for supplying liquid to the outside;
A movable wall portion that is displaced according to the remaining amount of liquid with respect to the fixed wall portion;
Both ends of the movable wall portion and the fixed wall portion are connected to the movable wall portion so as to change the inductance with the displacement of the movable wall portion, and an elastically deformable coil formed of a conductor,
A liquid storage tank, comprising: a pair of terminals provided on the fixed wall portion and connected to both ends of the coil to detect a change in inductance from the outside.   The liquid storage tank according to claim 1, wherein the coil has an elastic force that urges the movable wall portion so that the liquid storage tank has a negative pressure. A liquid mounting tank on which the liquid storage tank according to claim 1 or 2 is mounted so as to be replaceable, and a liquid for discharging liquid supplied from the liquid storage tank mounted on the tank mounting section. An image forming apparatus that forms an image on a print medium using an ejection head,
A pair of connection terminals formed in the tank mounting portion and connected to a pair of terminals of the liquid storage tank;
An image forming apparatus comprising: a liquid remaining amount detecting unit which is connected to the pair of connection terminals and detects the remaining amount of liquid in the liquid storage tank based on a change in inductance of the coil. A tank holder in which the liquid storage tank according to claim 1 or 2 is mounted in a replaceable manner, and a liquid discharge head for discharging the liquid supplied from the liquid storage tank mounted in the tank holder. A cartridge mounting portion in which a head cartridge formed on the tank holder and having a pair of intermediate terminals for detecting a change in inductance from the outside through a pair of terminals of the liquid storage tank is detachably mounted An image forming apparatus for forming an image by discharging liquid from the liquid discharge head onto a print medium,
A pair of connection terminals formed in the cartridge mounting portion and conducting to a pair of intermediate terminals of the head cartridge;
An image forming apparatus comprising: a liquid remaining amount detecting unit which is connected to the pair of connection terminals and detects the remaining amount of liquid in the liquid storage tank based on a change in inductance of the coil. 5. The image forming apparatus according to claim 3, wherein the liquid remaining amount detection unit includes an oscillation control circuit that changes an oscillation frequency in accordance with an inductance of the coil.

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