JP2014097604A - Liquid detection device and liquid discharge recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid detection device and a liquid discharge recording device capable of detecting a liquid storage amount with a small-sized structure even when a liquid storage part that can be used in a plurality of positions is used in a different position.SOLUTION: The liquid detection device includes: a first electrode 88 and a second electrode 89 disposed in a liquid storage space of the liquid storage part; and determination means 90 and 100 for determining electric conductivity between the first electrode and the second electrode. In each position of the liquid storage part 22K, a lower end 88a of the first electrode 88 and a lower end 89a of the second electrode 89 are disposed at different levels.

Description

  The present invention relates to a liquid detection apparatus for detecting a liquid storage state in a liquid storage section, and a liquid discharge recording apparatus that discharges liquid to perform recording on a recording medium.

  In a liquid discharge recording apparatus that records an image or the like by attaching a liquid discharged from a liquid discharge head to a recording medium, a liquid storage unit that stores the liquid to be supplied to the discharge unit of the liquid discharge head and the liquid to be supplied Is provided. As the liquid storage unit, one provided integrally with the liquid discharge head, or one provided detachably with respect to the liquid discharge head is known. In addition, when the amount of liquid stored in the liquid discharge head is less than a certain amount, the liquid storage unit is driven by a pump or the like to supply liquid from the liquid storage unit to the liquid supply unit. . According to this, the inside of the liquid storage part is maintained at an appropriate negative pressure, and a meniscus can be formed in the nozzle.

  By the way, various detection means for detecting whether or not the amount of liquid stored in the liquid storage part has become a certain amount or less have been proposed. For example, Patent Document 1 discloses a means for determining the position (liquid amount) of a liquid surface using a phenomenon in which a difference in reflection amount of light emitted from a light emitting element changes depending on the presence or absence of liquid. This means has a configuration in which the liquid level detection unit of the liquid storage unit is formed of a transparent material capable of transmitting light, and a light emitting element and a light receiving element are arranged in the vicinity of the outside of the liquid level detection unit. However, in the liquid amount detection means having such a configuration, the liquid that has come into contact with the liquid level detection unit may adhere. In this case, it is determined that there is liquid even if the liquid level is below the detection position level. In addition, the liquid storage section needs to be formed of a material that is difficult to be altered by the liquid. That is, it is necessary to use a material having both liquid resistance and light transmission properties, but there is a problem that the material selection is difficult.

  As a liquid quantity detection means that can avoid the above problems, there is a so-called electrode-type liquid quantity detection means that utilizes the electrical conductivity of a liquid (see Patent Document 2). In this detection means, a pair of liquid level detection electrodes are provided in the liquid storage unit, and when the two electrodes become non-conductive, it is determined that the liquid level has reached below the position in the vertical direction of at least one of the electrodes. Is done. This electrode-type liquid amount detection means has the advantage that it is excellent in liquid resistance and can be used for a long time.

  By the way, the liquid discharge recording apparatus has been used for various purposes as the market in the printing field has been expanded in recent years, and its usage pattern has also changed. For example, in addition to the normal recording posture in which ink droplets are ejected toward the vertical lower surface, the recording posture may be used in which ink droplets are ejected in a direction perpendicular to the vertical lower surface. That is, when the liquid storage container has a rectangular parallelepiped shape, when the surface provided with a plurality of discharge nozzles is the first surface, the surface orthogonal to the first surface and parallel to the nozzle row is the second surface, There are cases where the first surface is discharged as a vertical lower surface and discharge is performed when the second surface is a vertical lower surface. At this time, if the first surface is a vertical lower surface, the ink droplets are ejected toward the vertical lower surface, and if the second surface is a vertical lower surface, the ink droplets are directed in a direction (horizontal direction) perpendicular to the vertical lower surface. Discharged. Thus, by making it possible to select the recording posture of the recording apparatus, it is possible to realize effective use of the installation space, reduction of the occupied area, and the like.

JP 2000-198222 A JP 2007-313732 A

  However, as described above, it is possible to change the orientation of the recording apparatus and change the ink ejection direction to ejection with the first surface as the vertical lower surface and ejection with the second surface as the vertical lower surface. In the recording apparatus, the posture of the liquid storage unit also changes as the posture changes. For this reason, in order to accurately detect the liquid level in the liquid storage unit, two sets (at least four) of electrodes as the liquid level detection means are required in the liquid storage unit. In this case, it is difficult to incorporate two sets of liquid level detection means in the limited space of the liquid storage unit that is integrally or detachably attached to the discharge unit. There is a problem that the volume of the ink supply chamber in the liquid ejection head is compressed.

  The present invention provides a liquid detection apparatus and a liquid discharge recording apparatus capable of detecting a liquid storage amount with a small configuration even when liquid storage units that can be used in a plurality of postures are used in different postures. Objective.

In order to achieve the above object, the present invention has the following configuration.
That is, the first aspect of the present invention is a liquid detection device for detecting a storage state of a liquid in a liquid storage space formed in a liquid storage unit that can be used in a plurality of different postures, the liquid storage unit First and second electrodes disposed in the liquid storage space, and determining means for determining electrical conductivity between the first electrode and the second electrode, and the liquid storage unit In each of the postures, the lower end portion of the first electrode and the lower end portion of the second electrode are disposed at different positions in the vertical direction.

  In the second aspect of the invention, a discharge unit that discharges a liquid, a liquid storage container that supplies the liquid stored in the liquid storage space to the discharge unit, and a storage state of the liquid in the liquid storage space are detected. A liquid detection recording apparatus for forming an image by discharging the liquid onto a recording medium, wherein the discharge section and the liquid storage container are in a first posture and a second posture. The liquid detection device is a liquid detection device for detecting a storage state of a liquid in a liquid storage space formed in a liquid storage unit that can be used in a plurality of different postures, and the liquid storage unit First and second electrodes disposed in the liquid storage space, and determining means for determining electrical conductivity between the first electrode and the second electrode, and the liquid storage unit Under the first electrode in each posture Characterized in that the lower end parts and the second electrode are disposed in different positions in the vertical direction.

  According to the present invention, even when liquid storage containers that can be used in a plurality of postures are used in different postures, with a small configuration that can suppress the amount of liquid storage in the liquid storage space of the liquid storage container, The liquid storage amount can be detected.

1 is a front view schematically showing a first embodiment of a liquid discharge recording apparatus according to the present invention. FIG. 4 is a schematic diagram of a recording / conveying unit of the liquid discharge recording apparatus according to the embodiment of the present invention, and shows a case where the recording / conveying unit is installed to take a second posture. FIG. 3 is a block diagram illustrating a control system of the liquid discharge recording apparatus according to the present invention. FIG. 6 is a diagram schematically illustrating a path through which a liquid passes from a liquid tank to a recording head in the recording apparatus of the present embodiment. FIG. 5 is an enlarged view of the recording head shown in FIG. 4 and its periphery. FIGS. 5A and 5B are modifications of the recording head shown in FIG. 5, where FIG. 5A is a front view, FIG. 5B is a side view, and FIG. It is the figure which showed the AA cross section of FIG. It is a figure which shows the structure of an electrode unit, (a) is a front view, (b) is a side view, (c) is a bottom view. FIG. 4 is a front view and a side view showing a positional relationship between a liquid stored in the liquid storage space and an electrode protruding into the liquid storage space, and shows a state where the recording head is in a first posture. FIG. 6 is a front view and a side view showing a positional relationship between a liquid stored in the liquid storage space and an electrode protruding into the liquid storage space, and shows a state where the recording head is in a second posture. It is a figure which shows the detection circuit part in this embodiment. It is a figure which shows the example of determination of the electrical storage computed in this embodiment, and the storage state of the liquid corresponding to it. It is a figure which shows the electrode in the 2nd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a front view schematically showing a first embodiment of a liquid discharge recording apparatus (hereinafter also simply referred to as a recording apparatus) according to the present invention. The recording apparatus 10 is connected to the host PC 12, and based on the recording information transmitted from the host PC 12, the four liquid discharge heads 22K, 22C, 22M, and 22Y are connected to a recording medium (hereinafter also referred to as roll paper) P. Then, recording is performed by discharging liquids of four colors. That is, black, cyan, magenta, and yellow liquids (inks) are discharged from four liquid discharge heads (hereinafter also referred to as recording heads) 22K, 22C, 22M, and 22Y, respectively. The recording heads are arranged in parallel along the conveyance direction of the recording medium P (the direction of arrow A in the figure). In the present embodiment, four recording heads are arranged in the order of 22K, 22C, 22M, and 22Y from the upstream in the transport direction. Each recording head has a discharge port, which is an opening of a nozzle that discharges ink, in a range that is longer than the maximum width of the recording medium to be used along a direction that intersects the conveyance direction of the recording medium (direction orthogonal to the drawing). This is a so-called line head that is arranged over the entire area. In addition, the recording apparatus 10 performs recording by conveying the recording medium P without moving each recording head and ejecting ink from each of a plurality of nozzles arranged in the recording head. Ink is discharged from each nozzle by driving a discharge energy generating element provided in each nozzle. In this embodiment, an electrothermal conversion element (heater) is used as the discharge energy generating element. However, an electromechanical conversion element such as a piezo can be used as the discharge energy generating element.

  When recording is performed by the recording apparatus, recording is performed by discharging a liquid from the nozzle outlet by driving a heater provided in the recording head without moving each recording head. In this case, in a normal usage pattern, the ejection port surface (first surface) 2Ks, 22Cs, 22Ms, 22Ys on which the ejection port of the recording head is formed is a lower surface orthogonal to the vertical direction, and ink droplets are in the vertical direction. Is discharged along. In the present embodiment, as shown in FIG. 2, it is also possible to adopt a usage pattern in which the ejection port surface of the recording head is parallel to the vertical direction, that is, a usage pattern in which the recording head is rotated 90 degrees. . In this case, liquid is discharged from each discharge port on the discharge port surface along a direction orthogonal to the discharge port surface. Hereinafter, the posture of the recording head in the usage pattern in which the discharge port surface is a lower surface orthogonal to the vertical direction is the first posture, and the posture of the recording head in the usage pattern in which the discharge port surface is parallel to the vertical direction is the second posture. That's it.

  In the recording head, the ejection state may change due to adhesion of foreign matter such as dust or liquid droplets to the ejection port surfaces 22Ks, 22Cs, 22Ms, and 22Ys in accordance with the liquid ejection operation, which may affect recording. Therefore, the recovery unit 40 is incorporated in the recording apparatus 10 so that liquid can be stably discharged from the recording heads 22K, 22C, 22M, and 22Y. By periodically cleaning the discharge port surface by the recovery unit 40, the liquid discharge state from the nozzles of the recording heads 22K, 22C, 22M, and 22Y can be recovered to the initial good liquid discharge state. The recovery unit 40 is provided with a cap 50 that removes liquid from the outlet faces 22Ks, 22Cs, 22Ms, and 22Ys of the four recording heads 22K, 22C, 22M, and 22Y during the cleaning operation. The cap 50 is provided independently for each of the liquid discharge heads 22K, 22C, 22M, and 22Y, and includes a blade, a liquid removing member, a blade holding member, a cap, and the like. In the following description, when it is not necessary to distinguish each recording head, the reference numeral attached to the recording head may be set to 22. Similarly, when it is not necessary to distinguish each discharge port surface, the code | symbol attached | subjected to a discharge port surface may be set to 22s.

The recording medium P is supplied from the roll paper supply unit 24 and is transported in the direction of arrow A by the transport mechanism 26 incorporated in the recording apparatus 10. The transport mechanism 26 includes a transport belt 26a that transports the roll paper P, a transport motor 26b that rotates the transport belt 26a, a roller 26c that applies tension to the transport belt 26a, and the like.
In the recording operation, when the roll paper P being conveyed reaches below the recording head 22K for discharging black ink, black ink is discharged from the recording head 22K based on the recording information sent from the host PC 12. Similarly, each color liquid (ink) is ejected onto the roll paper P in the order of the recording heads 22C, 22M, and 22Y, and a color image is recorded.

  The recording apparatus 10 includes main tanks 28K, 28C, 28M, and 28Y that store liquid supplied to each recording head, a pump 72 (see FIG. 4) for replenishing each recording head with liquid, and a cleaning operation. A pump 85 or the like is provided. In the present embodiment, the recording heads 22C, 22M, and 22Y and the transport mechanism 26 constitute a recording / conveying unit 42.

  FIG. 2 is a schematic diagram showing a case where the recording / conveying unit 42 is installed so that the ejection port surface of the recording head is orthogonal to the vertical lower surface, that is, the case where the recording / conveying unit 42 is installed so as to take the second posture described above. . In the state shown in FIG. 2, ink droplets are ejected along a plane (horizontal plane) perpendicular to the vertical lower surface. The roll paper P is conveyed in parallel to the ejection port surfaces 22Ks, 22Cs, 22Ms, and 22Ys of the recording heads 22K, 22C, 22M, and 22Y, and a color image is recorded by the ink ejected from each recording head.

  FIG. 3 is a block diagram showing a control system of the recording apparatus 10 of FIG. Recording information and commands transmitted from the host PC (host device) 12 are received by the CPU 100 via the interface controller 102.

  The CPU 100 is an arithmetic processing unit that performs overall control such as reception of recording information, recording operation, and handling of the roll paper P in the recording apparatus 10. After analyzing the received command, the CPU 100 develops a bitmap of the image data of each color component of the recording data in the image memory 106. In the operation process performed before recording, the capping motor 122 and the head up / down motor 118 are driven via the output port 114 and the motor drive unit 116, and the recording heads 22K, 22C, 22M, and 22Y are separated from the cap 50 for recording. Move to position. Further, the CPU 100 drives the roll motor 126 that feeds the roll paper P through the output port 114 and the motor driving unit 116, the transport motor 120 that transports the roll paper P, and the like to transport the roll paper P to the recording position. Control. Further, the fan motor 36a of the pressure control pump 36 for keeping the inside of the recording head 22 at a negative pressure is driven.

  When performing recording, the leading end detection sensor 109 detects the leading end position of the roll paper P in order to determine the timing (recording timing) at which ink is ejected onto the rolled paper P conveyed at a constant speed. Thereafter, in synchronism with the conveyance of the roll paper P, the CPU 100 sequentially reads the recording information from the image memory 106, and the read recording information is sent to the recording heads 22K, 22C, 22M,. 22Y.

  The operation of the CPU 100 is executed based on a processing program stored in the program ROM 104. The program ROM 104 stores processing programs and tables corresponding to the control flow. The CPU 100 uses a work RAM 108 as a working memory. Further, the CPU 100 drives the pump motor 124 via the output port 114 and the motor driving unit 116 during the cleaning and recovery operations of the recording heads 22K, 22C, 22M, and 22Y, and controls the pressurization and suction of the liquid. .

  When the recording head 22 is filled with liquid, the CPU 100 determines the storage state of the liquid stored in a liquid storage unit (described later) provided in the recording head 22 based on the detection signal output from the liquid detection device 107. To do. Thereafter, the pump motor 124 is driven via the output port 114 and the motor drive unit 116 according to the determined liquid storage state, and the supply of liquid is stopped or a defoaming sequence for eliminating bubbles in the recording head 22 is executed. To do.

  FIG. 4 is a diagram schematically showing a path through which the liquid passes from the liquid tank 70 to the recording head 22K in the recording apparatus of the present embodiment. Since each recording head has the same structure, only the recording head 22K for black ink will be described below as an example.

  The recording apparatus 10 includes a recording head 22K and a liquid supply device 60 that supplies liquid to the recording head 22K. The liquid supply device 60 includes a liquid tank 70 that can be attached to and detached from the main body of the recording apparatus 10, and a liquid supply pump 72 that is disposed in the middle of a liquid supply path 62 that connects the liquid tank 70 and the recording head 22K. It has the composition provided. The supply pump 72 is responsible for supplying the liquid to the liquid storage unit 22Kr via the liquid filter 22F2.

  The recording head 22K includes a liquid storage unit 22Kr having a rectangular parallelepiped shape and a discharge unit 22KSi that can discharge liquid. The liquid storage unit 22Kr is provided with a liquid detection device 90 for detecting the storage state of the liquid L stored in the liquid storage space 22Krs formed therein. Details of the liquid detection device 90 will be described later. A discharge unit 22KSi is connected below the liquid storage unit 22Kr. The discharge portion 22KSi is formed by a nozzle 22Kn of the recording head 22K and a liquid supply port to the nozzle 22Kn.

  An air flow path 35 is connected to a space (hereinafter referred to as an air chamber) 22Kra filled with air via an air filter 22F1 above the liquid storage unit 22Kr. In addition, a decompression channel 34 is connected to an end of the air channel 35 so as to form a T shape together with the channel. The decompression channel 34 has one end 33 opened to the atmosphere and the other end connected to a pressure control pump 36. The pressure control pump 36 includes a pressure control fan 36a that is rotated by a fan motor 125 (see FIG. 4).

  A well-known detection sensor (not shown) for detecting the presence or absence of liquid in the liquid tank 70 is attached to the liquid tank 70. The liquid tank 70 is disposed outside the main body of the recording apparatus, and is connected to the recording head 22K via a liquid supply path 62. The liquid tank 70 is provided with an air release valve 74 for bringing the internal pressure of the liquid tank 70 to atmospheric pressure.

  While the recording operation is being performed, the liquid in the liquid storage unit 22Kr decreases due to liquid consumption due to recording. When it is determined that the liquid level 22Krs has reached a certain level or less based on the detection signal of the liquid detection device 86 of the liquid storage unit 22Kr, the air release valve 74 of the liquid tank 70 is opened, and the liquid supply pump 72 is Be operational. Thereby, the liquid is sucked from the liquid tank 70, and the sucked liquid is supplied into the liquid storage unit 22Kr.

  On the other hand, the CPU 100 determines whether or not the liquid level Ls of the liquid L stored in the liquid storage space 22Krs of the liquid storage unit 22K has reached a certain liquid level based on the detection signal of the liquid detection device 86. . If a determination result indicating that the liquid level has reached a certain level is obtained, the CPU 100 stops driving the liquid supply pump 72 and seals the air release valve 74 of the liquid tank 70 to supply the liquid. Stop. In this embodiment, since the tube pump is used as the supply pump 72, the communication between the liquid tank 70 and the liquid storage unit 22Kr is blocked when the liquid supply pump 72 is stopped.

  FIG. 5 is an enlarged view of the recording head 22K and its periphery. At the time of recording, it is necessary to apply an appropriate negative pressure to the recording head 22K in order to form a meniscus on the nozzle 22Kn. Accordingly, during the recording operation, the atmospheric valve 31 is opened, and an air flow in the C direction is generated by driving the pressure control pump 36. As a result, the air chamber 22Ka and the nozzle 22Kn in the recording head 22K are kept in a reduced pressure state. In the present embodiment, since the liquid storage unit 22Kr communicating with the atmosphere is disposed above the discharge unit 22Ksi, the head pressure from the liquid level 22Krs is opened at the opening of the nozzle 22Kn when the atmospheric valve 31 is opened. H acts as a positive pressure on the opening of the nozzle 22Kn. Therefore, the amount of pressure reduction into the air chamber 22Ka by the pressure control pump 36 can be set to a water head pressure H or higher so that a negative pressure can be applied to the nozzles 22Kn of the recording head 22K.

FIG. 6 shows a modification of the recording head 22K shown in FIG. 5. FIG. 6A shows a front view, FIG. 6B shows a side view, and FIG. 6C shows a bottom view.
As shown in FIGS. 6b and 6c, the shape of the recording head 22K is formed with a bulging portion 22Kt that swells toward the air filter 22F1. By having the bulging portion 22Kt, the air bubbles 69 generated by the discharge easily float toward the arrangement position of the air filter 22F1 inside the recording head 22K.

  FIG. 7 is a view showing a cross section taken along the line AA of FIG. The nozzle 22Kn in the discharge part 22KSi is formed by joining two chips of the heater board 22Kh and the supply port forming member 22Kt. The supply port forming member 22Kt is in contact with the liquid storage portion 22Kr and communicates with the liquid flow path of the supply port forming member 22Kt. Further, the heater board 22Kh and the head substrate 24K are connected by an energizing wire 26K, and exchange signals between the recording head 22K and the external substrate. Further, the discharge unit 22KSi, the head substrate 24, the liquid chamber 25K, and the like are fixed to the base plate 23K by means not shown.

  By the way, dissolved gas in the liquid may be deposited in the liquid storage unit 22Kr during recording operation and standby, or bubbles 69 may be mixed in by the liquid supply operation. The dissolved gas in the liquid refers to air dissolved in the liquid, and generally dissolves more as the temperature is lower. As an example in which the dissolved gas is deposited in the liquid, the temperature of the liquid rises due to the heat of the heater provided in the discharge unit 22KSi as the liquid moves toward the discharge unit 22KSi during the recording operation. There are several cases. Moreover, gas permeation in the supply path 62 is mentioned as an example in which bubbles are included in the liquid supplied into the liquid storage unit 22Kr. Normally, the inside of the supply path 62 is filled with a liquid. However, when the supply path 62 is constituted by a tube or the like, air in the atmosphere permeates through the tube and mixes with time. Such bubbles 69 are mixed into the liquid storage unit 22Kr along with the liquid supply operation. These bubbles are accumulated so as to accumulate in the liquid storage unit 22Kr, and eventually cause a phenomenon that causes a problem in recording quality, such as blocking the liquid supply path. For this reason, conventionally, a method of discharging liquid that does not contribute to recording at a predetermined interval and simultaneously discharging bubbles 69 to remove the bubbles or pushing the accumulated bubbles to a predetermined position (for example, a liquid tank). I was taking.

  On the other hand, in the liquid discharge recording apparatus of the present embodiment, bubbles can move upward by their own buoyancy in the flow path from the contact surface between the supply port forming member 22Kt and the liquid chamber 25K to the liquid liquid level 22Krs. Is formed. For this reason, the bubbles 69 mixed in the liquid storage unit 22Kr move upward and reach the liquid level 22Krs and disappear (hereinafter referred to as gas-liquid separation). At this time, since a negative pressure is applied to the recording head 22K, the liquid corresponding to the volume of the bubbles is supplied to the liquid chamber simultaneously with the disappearance of the bubbles, thereby ensuring the continuity of the recording operation.

  However, when a liquid containing a relatively large amount of surfactant added to improve the permeability to the recording medium is used, if a large number of bubbles are mixed during the liquid supply, a foam layer is formed above the liquid in the liquid storage unit. Formed and won't disappear for a long time. In this case, the liquid is not supplied to the liquid chamber due to the presence of the bubbles, and the liquid in the liquid storage unit is reduced by the volume of the bubbles, and the continuity of the recording operation may not be maintained. Further, the reason why the continuity of the recording operation cannot be maintained is also caused by a shortage of the liquid storage amount in the liquid storage unit 22Kr. Therefore, the liquid discharge recording apparatus according to the present embodiment includes a liquid detection device capable of detecting the amount of liquid stored in the liquid storage unit and the liquid storage state such as the generation state of bubbles in the liquid storage unit. Yes.

Hereinafter, the liquid detection apparatus according to the present embodiment will be described with reference to FIGS.
The liquid detection device 90 according to the present embodiment includes an electrode unit 80 (see FIGS. 8 to 10) having a plurality of electrodes shown in FIGS. 8 to 10, and a detection circuit unit 93 (FIG. 11) connected to the electrode unit 80. Reference). Furthermore, the liquid detection apparatus in the present embodiment also includes a CPU 100 as a determination unit that determines the liquid storage state in the liquid storage unit based on the detection signal output from the detection circuit unit 93.

  First, the electrode unit 80 will be described with reference to FIGS. 8A and 8B are diagrams showing the configuration of the electrode unit. FIG. 8A is a front view, FIG. 8B is a side view, and FIG. 8C is a bottom view. In FIG. 8, the electrode unit 80 includes an electrode support 81 having a rectangular parallelepiped shape, and first, second, and third electrodes 88, 89, 87 fixed to the electrode support 80. Each of the electrodes 88, 89, 87 protrudes outward from one outer surface 81 a of the electrode support 81 and also protrudes outward from the other outer surface 81 b of the electrode support 81. The first electrode 88 has the shortest length protruding from one outer surface 81 a of the electrode support 81. Further, the second electrode 87 and the third electrode 89 protrude from the outer surface 81a by the same length. As shown in FIGS. 4, 5, and 6, the electrode support 81 that holds these electrodes is fixed to the surface of the liquid storage unit 22 </ b> Kr of the recording head 22 </ b> K that faces the surface where the ejection unit 22 </ b> KSi is provided. Has been. In each electrode, a portion protruding from the outer surface 81a of the electrode support 81 is located in the liquid storage space 22Krs, while a portion protruding outward from the outer surface 81b is exposed to the outside. The electrode portion exposed to the outside is connected to an electric board (not shown) via a harness (not shown) or the like. The third electrode 87 is a common electrode connected to the ground of the electric substrate.

  9 and 10 are a front view and a side view showing a positional relationship between the liquid stored in the liquid storage space 22Krs of the liquid storage unit 22Kr and the electrodes 87, 88, 89 protruding into the liquid storage space 22Krs. It is.

  FIG. 9 shows a state in which the recording head 22K is maintained in a posture (first posture) in which liquid is ejected from the ejection portion 22Ks along the vertical direction (Vd direction). In this first posture, a surface (first surface) 22Kr1 corresponding to the bottom surface of the liquid storage portion 22Kr having a rectangular parallelepiped shape is a surface (horizontal plane) orthogonal to the vertical direction. The discharge portion 22Ks is fixed to the first surface 22Kr1. Furthermore, since the liquid storage unit 22Kr has a rectangular parallelepiped shape, a surface (second surface) 22Kr2 orthogonal to the first surface 22Kr1 is a surface (vertical surface) parallel to the vertical direction (Vd direction).

  When the recording head 22K is in the first posture, the lower end portions of the second electrode 89 and the third electrode 87 are lower in the vertical direction than the lower end portion of the first electrode 88 in the liquid storage portion 22Kr. Located at the same position. That is, the distance from the second and third lower end portions to the first surface 22Kr1 is shorter than the distance from the lower end portion of the first electrode 88 to the first surface 22Kr1. Therefore, in the first posture, when the liquid stored in the liquid storage unit 22Kr decreases from the state of being in contact with all the electrodes as shown in FIG. Is in a non-contact state with the liquid at the earliest stage (see FIG. 9B). When the liquid further decreases from the stage shown in FIG. 9B and the liquid level falls, as shown in FIG. 9A, all the electrodes 88, 89, 87 are in a non-contact state with the liquid.

  On the other hand, FIG. 10 shows a state in which the recording head 22K is maintained in a posture (second posture) in which the liquid L is ejected from the ejection portion 22Ks of the recording head 22K in a direction (horizontal direction) orthogonal to the vertical direction. ing. In the second posture, the first surface 22Kr1 is a surface (vertical surface) parallel to the vertical direction Vd, and the second surface 22Kr2 is a surface (horizontal plane) orthogonal to the vertical direction. In this embodiment, also in this second posture, the lower ends of the second electrode 89 and the third electrode 87 are at the same position below the lower end of the first electrode 88 in the vertical direction. Located in. That is, the distance from the lower end portions of the second and third electrodes 89 and 87 to the second surface 22Kr2 which is the lower surface in this posture is from the lower end portion of the first electrode 88 to the second surface 22Kr2. Shorter than distance.

  Accordingly, even in the second posture, when the liquid decreases from the state shown in FIG. 10C in which all the electrodes are in contact with the liquid and the liquid level descends, the second position is obtained as shown in FIG. 10B. One electrode 88 is not in contact with the liquid at the earliest stage. Thereafter, when the liquid L is further reduced and the liquid level L is lowered, all the electrodes 88, 89, 87 are brought into a non-contact state with the liquid as shown in FIG.

  As described above, in this embodiment, the second and third electrodes 87 and 89 are always positioned below the first electrode 88 in both the first and second postures. The positions of the lower end portions of the second and third electrodes 87 and 89 indicate the liquid surface lower limit position in the liquid storage portion. The liquid level lower limit position is the position of the liquid level at which liquid supply should be started to the liquid storage unit 22Kr, and it is assumed that the continuity of the recording operation is maintained, such as the volume of the liquid storage unit 22Kr and the maximum duration of the recording operation. Is set in advance.

Next, a detection circuit unit as detection means for detecting the positional relationship between the liquid in the liquid storage unit 22Kr and each electrode of the electrode unit 80 will be described.
FIG. 11 is a diagram showing the detection circuit unit 90 electrically connected to each electrode of the electrode unit 80 having the above configuration. The detection circuit unit 90 shown here has an impedance or electric current between the first and second electrodes 88 and 89 and the common electrode 87 when a constant voltage is applied to the first and second electrodes 88 and 89. It is a circuit for measuring conductivity. Based on the detection signal output from this circuit, the positional relationship between each electrode and the liquid level is determined. That is, when a liquid contacts the first electrode 88 and the second electrode, both electrodes are in a conductive state via the liquid, so that the impedance is low and the electrical conductivity is high. On the other hand, when the first electrode 88 and the second electrode 89 are not in contact with the liquid, the electrodes 88 and 89 and the third electrode 87 are electrically cut off and become high impedance. The rate is low.

  In the following, the configuration shown in FIG. 11 will be described in more detail. One input terminal 92b1 of the rectifier 92b is connected to the first electrode 88 of the electrode unit 80, and the other input terminal 92b2 is connected to the ground of the recording apparatus. Has been. Further, the second electrode 89 is connected to one input terminal 92a1 of the rectifier 92a, and the other input terminal 92a2 is connected to the ground of the recording apparatus. Further, the third electrode 87 is connected to the ground as a common electrode. The voltage generated by the voltage generation unit (voltage generation means) 91 is applied to the first electrode 88 and the second electrode 89. The voltage generated by the voltage generator 91 is an alternating voltage, and by applying this alternating voltage, the liquid is prevented from being electrolyzed by the current flowing between the electrodes.

  In the detection circuit unit 90 having the above-described configuration, the alternating voltage generated by the voltage generation unit 91 is applied to the first electrode 88 and the second electrode 89 installed in the recording head 28K. Here, a voltage attenuated according to the impedance between the first electrode 88 and the third electrode 87 is input to the input terminal 92a1 of the rectifying unit 92a. Thereby, a signal corresponding to the voltage difference between the voltage input to the input terminal 92a and the voltage input to the input terminal 92b, that is, the potential difference between the first electrode 88 and the third electrode 89 is output from the rectifier 92a. Is output. Similarly, a voltage attenuated according to the impedance between the second electrode 89 and the third electrode 87 is input to the input terminal 92b1 of the rectifying unit 92b. The rectifier 92a outputs a signal corresponding to the voltage difference between the voltages input to the input terminals 92a and 92b, that is, the potential difference between the second electrode 89 and the third electrode 87. Detection signals output from the rectifiers 92a and 92b are output to the CPU 100. The CPU 100 calculates the electric conductivity between the electrodes using the input detection signal, and determines the liquid storage state in the recording head 28K based on the electric conductivity.

  FIG. 12 shows an example of the determination result of the calculated electrical conductivity and the storage state of the corresponding liquid. In the example shown in FIG. 12, if the calculated electrical conductivity is equal to or higher than the first value (0 μs or higher) and (less than the second value (less than 100 μs), it is determined that liquid exists between the electrodes. If the calculated electrical conductivity is greater than or equal to the second value (100 μs or greater) and less than the third value (less than 3000 μs), it is determined that bubbles are present between the electrodes. If the value is equal to or greater than 3000 μs, it is determined that air exists between the electrodes, and the CPU 100 drives predetermined notification means (display unit, sound generation means) according to the determined storage state of the liquid. Thus, in this embodiment, in the present embodiment, not only the liquid level position, that is, the amount of stored liquid, but also bubbles are generated on the liquid level as the liquid storage state. Whether or not For this reason, it is possible to make the user recognize the liquid storage state more appropriately.The determination of the correspondence between the electrical conductivity and the liquid level state is, for example, the relationship shown in FIG. This can be realized by storing the data to be stored in the table memory in advance and reading the storage state of the liquid based on the electric conductivity.

  As described above, according to the present embodiment, the storage state of the liquid is properly detected in both the first posture and the second posture by disposing one set of three electrodes in the liquid storage unit. It becomes possible. For this reason, the volume by which a liquid storage part is occupied by an electrode can be suppressed, and the liquid storage amount in a liquid storage part can be increased.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. In the figure, the same or corresponding parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
In the second embodiment, the shapes of the end portions of the three electrodes 188, 189, 187 provided in the liquid detection device 90 are different from the electrodes 188, 189, 187 in the first embodiment shown in FIG. They are formed in different shapes. That is, the electrode shown in FIG. 13 has an L-shaped bent shape as shown in FIG. The end portion 187a of the third electrode 187 and the end portion (second detection surface) 189a of the second electrode 189 are located on the lower side when the recording head 22 is used in the second posture as shown in FIG. It will be in the state bent toward. Further, the end portion (first detection surface) 188a of the first electrode 188 is bent upward when the recording head 22K is in the second posture.

  According to the liquid detection device in the second embodiment configured as described above, it is possible to detect liquid in two postures as in the first embodiment. Furthermore, since the end portion of the electrode has a bent shape as described above, the contact area with the liquid increases as compared with an electrode whose tip is not bent, and the change in the liquid level is detected more accurately. It becomes possible.

(Other embodiments)
In each of the above embodiments, when the cuboid-shaped liquid storage container takes either the first posture or the second posture, the lower ends of the second and third electrodes of the three electrodes are The length and position of each electrode are determined so that it is always positioned vertically below the one electrode. However, the present invention is not limited to the above embodiments.

  For example, the shape of the liquid storage unit is not limited to a rectangular parallelepiped, but may be other shapes. In the above embodiment, the second posture is a posture rotated 90 degrees from the first posture. However, the first posture may be rotated from the first posture to another predetermined angle. Is possible. Furthermore, the present invention can be applied to the case where the number of postures that can be used is not limited to two but three or more. Moreover, it is also possible to arrange | position an electrode so that the 3rd electrode which is a common electrode among the 1st-3rd electrodes may always be vertically lower than another electrode in each attitude | position of a liquid storage part. Yes, this further increases the storage state of the detectable liquid.

  In addition, the number of electrodes arranged in the liquid storage space can be two. In this case, if the lower end portion of the first electrode and the lower end portion of the second electrode are arranged at different heights and the electrical conductivity between the electrodes is obtained, the first and second postures are obtained. In either case, the liquid storage state can be detected. In this case, either one of the first electrode and the second electrode is arranged so as to be always positioned downward in the vertical direction in the first and second postures, and the electrode is connected to the ground. In addition, the electrode positioned in the vertical direction is connected to one terminal of the rectifier as in the first embodiment, and the other input terminal of the rectifier is connected to the ground. Then, if the electrical conductivity between the first electrode and the second electrode is obtained based on the detection signal output from the rectifier, the liquid storage unit in both the first and second postures. The storage state of the liquid can be determined. However, in this embodiment, it is possible to determine whether or not the liquid is in contact with the first electrode and whether or not bubbles are formed between the first electrode and the second electrode. However, the storage position of the liquid with respect to the second electrode cannot be determined as in the first embodiment.

  In each of the above-described embodiments, the case where the liquid storage unit is integrally attached to the liquid discharge head has been described as an example. Applicable. In addition, the liquid detection device of the present invention can be applied to a recording apparatus that is provided in the recording apparatus main body in a state where the liquid storage container and the liquid discharge head are separated, and is used in a different posture. Furthermore, the liquid detection apparatus according to the present invention can also be applied to detection of a liquid storage state in a liquid storage container not related to the recording apparatus.

DESCRIPTION OF SYMBOLS 10 Liquid detection apparatus 22K, 22C, 22M, 22Y Recording head 22Kr Liquid storage part 22Krs Liquid storage space 87a, 187a Lower end part of 1st electrode 88,188 1st electrode 89,189 2nd electrode 89a, 189a 2nd Lower end portion 87,187 third electrode 87a, 187a lower end portion of third electrode 90 liquid detection circuit 91 piezoelectric generating portion (voltage applying means)
92a, 92b Rectifier 100 CPU (determination means)
L Liquid Vd Vertical direction

Claims (14)

A liquid detection device for detecting a storage state of a liquid in a liquid storage space formed in a liquid storage unit usable in a plurality of different postures,
First and second electrodes disposed in a liquid storage space of the liquid storage unit;
Determining means for determining electrical conductivity between the first electrode and the second electrode;
The liquid detection device according to claim 1, wherein a lower end portion of the first electrode and a lower end portion of the second electrode are arranged at different positions in the vertical direction in each posture of the liquid storage unit.   The liquid detection apparatus according to claim 1, wherein the liquid storage unit can be used in at least a first posture and a second posture different from the first posture.   The liquid storage unit can be used in at least a first posture and a second posture different from the first posture, and the second posture is rotated by a predetermined angle from the first posture. The liquid detection device according to claim 1, wherein the liquid detection device is in a posture.   4. The liquid according to claim 3, wherein the lower end portion of the first electrode is positioned vertically lower than the lower end portion of the second electrode in any of the first and second postures. Detection device.   5. The liquid detection according to claim 4, wherein the lower end portion of the second electrode is positioned vertically below the lower end portion of the first electrode in both the first and second postures. apparatus.   In the first posture, the lower end portion of the first electrode is located vertically below the lower end portion of the second electrode, and in the second posture, the lower end portion of the second electrode is the first electrode. The liquid detection device according to claim 4, wherein the liquid detection device is located vertically below the lower end of the electrode.   The liquid detection apparatus according to claim 1, further comprising a determination unit that determines a storage state of the liquid stored in the liquid storage unit based on the electrical conductivity determined by the determination unit.   The liquid detection device according to claim 4, wherein the determination unit determines a liquid level position of a liquid stored in the liquid storage unit and a generation state of bubbles. A third electrode different from the first and second electrodes is further disposed in the liquid storage space;
The lower end of the third electrode is perpendicular to the lower end of the lower end of the first and second electrodes, which is positioned vertically below, in both the first and second postures. Set at the same height or below,
The determining means determines electrical conductivity based on a potential difference between the first electrode and the third electrode and a potential difference between the second electrode and the third electrode. The liquid detection device according to claim 1.   The determination means determines that a liquid surface exists at a position in contact with the first electrode and the second electrode when the electric conductivity is equal to or higher than a predetermined first value, and the electric conductivity is When the second value lower than the first value is equal to or higher than the first value and lower than the first value, it is determined that bubbles are accumulated between the first electrode and the second electrode, and the electric conductivity is 10. The liquid detection device according to claim 3, wherein when it is lower than the second value, it is determined that the liquid level is located below the second electrode. 11.   10. The electrode according to claim 1, wherein the electrode has a bent shape by a first detection surface that is horizontal in the first posture and a second detection surface that is horizontal in the second posture. The liquid detection device according to any one of the above. The liquid storage container has a rectangular parallelepiped shape having a first surface that is a horizontal lower surface in a first posture and a second surface that is orthogonal to the first surface and is a horizontal lower surface in the second posture. ,
The liquid detection apparatus according to claim 10, wherein the first detection surface of the electrode is parallel to the first surface, and the second detection surface is parallel to the second surface. A discharge unit that discharges liquid; a liquid storage container that supplies the liquid stored in the liquid storage space to the discharge unit; and a liquid detection device that detects a storage state of the liquid in the liquid storage space, A liquid discharge recording apparatus for forming an image by discharging liquid onto a recording medium,
The discharge unit and the liquid storage container can be used in a first posture and a second posture,
The liquid detection device includes:
A liquid detection device for detecting a storage state of a liquid in a liquid storage space formed in a liquid storage unit usable in a plurality of different postures,
First and second electrodes disposed in a liquid storage space of the liquid storage unit;
Determining means for determining electrical conductivity between the first electrode and the second electrode;
The liquid discharge recording apparatus according to claim 1, wherein the lower end portion of the first electrode and the lower end portion of the second electrode are arranged at different positions in the vertical direction in each posture of the liquid storage unit.   The liquid discharge recording apparatus according to claim 13, wherein the liquid discharge recording apparatus is detachably attached to the liquid storage unit.

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