Liquid ejecting apparatus and cartridge

A liquid ejecting apparatus includes an ejection portion and a circuit. The ejection portion has a plurality of ejection ports configured to eject liquid supplied from a liquid storage portion defining a liquid storage space configured to store liquid. The circuit is electrically connected to at least one of a bottom electrode and a side electrode. The circuit is configured to detect a capacitance between the bottom electrode and the side electrode. The bottom electrode is provided at a bottom surface of the liquid storage portion. The side electrode is provided at one side surface of the liquid storage portion and electrically isolated from the bottom electrode.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from Japanese Patent Application No. 2016-212612 filed Oct. 31, 2016. The entire content of the priority application is incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to a liquid ejecting apparatus which includes an ejection portion having a plurality of ports for ejecting liquid and a circuit for measuring a capacitance between electrodes. This disclosure also relates to a cartridge mountable on the liquid ejecting apparatus.

BACKGROUND

It is known to measure the remaining amount of ink in a cartridge by providing an electrode on each of a pair of side surfaces facing each other of a cartridge tank (i.e. a liquid storage portion), and then measuring a capacitance between the electrodes.

SUMMARY

According to one aspect, this specification discloses a liquid ejecting apparatus. The liquid ejecting apparatus includes an ejection portion and a circuit. The ejection portion has a plurality of ejection ports configured to eject liquid supplied from a liquid storage portion defining a liquid storage space configured to store liquid. The circuit is electrically connected to at least one of a bottom electrode and a side electrode. The circuit is configured to detect a capacitance between the bottom electrode and the side electrode. The bottom electrode is provided at a bottom surface of the liquid storage portion. The side electrode is provided at one side surface of the liquid storage portion and electrically isolated from the bottom electrode.

According to another aspect, this specification also discloses a cartridge configured to be mounted on a liquid ejecting apparatus including an ejection portion having a plurality of ejection ports configured to eject liquid and a circuit configured to detect a capacitance between electrodes. The cartridge includes a liquid storage portion, a bottom electrode, and a side electrode. The liquid storage portion defines a liquid storage space configured to store liquid supplied to the ejection portion. The bottom electrode is provided at a bottom surface of the liquid storage portion. The side electrode is provided at one side surface of the liquid storage portion and electrically isolated from the bottom electrode. When the cartridge is mounted on the liquid ejecting apparatus, at least one of the bottom electrode and the side electrode is electrically connected to the circuit, and a capacitance between the bottom electrode and the side electrode is detected by the circuit.

According to still another aspect, this specification also discloses a liquid ejecting apparatus. The liquid ejecting apparatus includes a liquid storage portion, an ejection portion, a bottom electrode, a side electrode, and a circuit. The liquid storage portion defines a liquid storage space configured to store liquid. The ejection portion has a plurality of ejection ports configured to eject liquid supplied from the liquid storage portion. The bottom electrode is provided at a bottom surface of the liquid storage portion. The side electrode is provided at one side surface of the liquid storage portion and electrically isolated from the bottom electrode. The circuit is electrically connected to at least one of the bottom electrode and the side electrode. The circuit is configured to detect a capacitance between the bottom electrode and the side electrode.

DETAILED DESCRIPTION

When providing an electrode on each of a pair of side surfaces facing each other of the liquid storage portion as above, if the distance between the electrodes becomes shorter, the capacitance becomes larger. This results in improvement of detection accuracy of the remaining amount of ink. However, in order to secure the liquid storage space, there is a limit to improve accuracy of the remaining amount by shortening distance between the electrodes.

In addition, when providing an electrode on each of a pair of side surfaces facing each other of the liquid storage portion as above, the rate of change of the capacitance to the remaining amount is linear. In such a case, the detection accuracy of the remaining amount in a vicinity of the empty level cannot be improved.

In view of the foregoing, an example of an object of this disclosure is to provide a liquid ejecting apparatus and a cartridge which improve detection accuracy of the remaining amount of ink in the vicinity of the empty level.

An aspect of this disclosure will be described while referring to the accompanying drawings. As shown inFIG. 1, a printer1according to one embodiment of this disclosure has a housing1x. Inside the housing1x, there is provided an ejection unit10, a conveyance unit20, a cartridge unit40, and a control unit50.

The cartridge unit40includes four ink cartridges:40B,40Y,40C,40M, each containing black ink, yellow ink, cyan ink, and magenta ink. The four cartridges40B,40Y,40C,40M is individually detachably mounted on the housing1x.

The ejection unit10includes a carriage11, a head12and a sub-tank unit13respectively mounted on the carriage11.

The carriage11is supported by two guide shafts11gextending in the scanning direction. When the endless belt11btravels with driving of a carriage motor11m, the carriage11reciprocates in the scanning direction.

As shown inFIG. 2, the head12includes a channel unit12mand an actuator unit12n.

The lower surface of the channel unit12mis an ejection surface12ahaving a plurality of ejection ports12x. As shown inFIG. 1, the ejection ports12xform four rows of ejection ports12B,12Y,12C,12M in the conveyance direction. The four rows of ejection ports12B,12Y,12C,12M are arranged side by side in the scanning direction, each of these rows is formed by a plurality of ejection ports12xejecting single color ink of black, yellow, cyan, or magenta, respectively.

As shown inFIG. 2, the channel unit12mincludes a common channel12yfor each color of the rows of ejection ports12B,12Y,12C,12M and individual channels12zfor each of the ejection ports12x. The individual channel12zis a channel formed from an exit of the common channel12yof a corresponding color to the ejection port12xvia a pressure chamber12z1. There is a plurality of the pressure chambers12z1opening in the upper surface of the channel unit12m.

The actuator unit12nincludes: a vibration plate12n1provided over the channel unit12mto cover the plurality of pressure chamber12z1, a piezoelectric layer12n2provided over the vibration plate12n1, and a plurality of individual electrodes12n3provided over the piezoelectric layer12n2so as to face each of the pressure chamber12z1. A part of the vibration plate12n1and the piezoelectric layer12n2in the area sandwiched between each individual electrode12n3and each pressure chamber12z1functions as an individual unimorph type actuator for each pressure chamber12z1. This part is deformable in response to the voltage application by a head driver12dto the individual electrode12n3. When the actuator deforms to be convex toward the pressure chamber12z1, the volume of the pressure chamber12z1decreases and the pressure within the pressure chamber12z1is applied to the ink therein, which results in ejection of ink from the ejection port12x.

As shown inFIG. 1, the sub-tank unit13includes four sub-tanks13B,13Y,13C,13M, each stores black ink, yellow ink, cyan ink, and magenta ink. Each of the four sub-tanks13B,13Y,13C,13M is connected to each of the four cartridges of corresponding color40B,40Y,40C,40M through flexible tubes15B,15Y,15C,15M of corresponding color.

The four sub-tanks13B,13Y,13C,13M have the same configuration. The four cartridges40B,40Y,40C,40M have the same configuration.

As shown inFIG. 3, each of the sub-tanks13B,13Y,13C,13M has a housing13x. Each of the cartridges40B,40Y,40C,40M also has a housing40x. Each of these housings13x,40xis a substantially rectangular parallelepiped shape and defines an ink storage space13v,40vfor storing ink therein.

The ink storage spaces40vof the respective cartridges40B,40Y,40C,40M communicate with the ink storage spaces13vof the sub-tanks13B,13Y,13C,13M of corresponding color through the tubes15B,15Y,15C,15M of corresponding color. The ink storage spaces13vof the respective sub-tanks13B,13Y,13C,13M communicate with the common channels12yof corresponding color in the head12through joints16of corresponding color.

The ink supplied from the ink storage space40vof each cartridge40B,40Y,40C,40M to the ink storage space13vof the sub-tank13B,13Y,13C,13M through the tube15B,15Y,15C,15M is temporarily stored in the ink storage spaces13vand then supplied to the head12through the joint16.

As shown inFIG. 4, the housings13xof the four sub-tanks13B,13Y,13C,13M are arranged in the scanning direction (a particular direction).

As shown inFIGS. 3 and 4, the sub-tank unit13is provided with a bottom electrode3a, four side electrodes3b, and four side electrodes3c. Each side electrode3bis not electrically connected to (that is, electrically isolated from) the bottom electrode3a. In other word, there is no electrical conduction between each side electrode3band the bottom electrode3a. Each side electrode3cis electrically connected to the bottom electrode3a, and is not electrically connected to the side electrode3b. The bottom electrode3aand the four side electrodes3care held at a ground potential.

The bottom electrode3ais provided at a bottom surface13xaof the housings13xof the four sub-tanks13B,13Y,13C,13M. As shown inFIG. 4, the bottom electrode3aextends in the scanning direction and is a common electrode for the four sub-tanks13B,13Y,13C,13M. The bottom electrode3afaces substantially an entire region of the ink storage spaces13vof the four sub-tanks13B,13Y,13C,13M in the vertical direction.

The four side electrodes3bare arranged at intervals in the scanning direction on a board (substrate)3xprovided at a side surface13xbof the housing13xof the four sub-tanks13B,13Y,13C,13M. The four side electrodes3bare individual electrodes for each of the four sub-tanks13B,13Y,13C,13M, and are electrically connected to a capacitance measurement circuit for sub-tank13s(refer toFIG. 6). The four side electrodes3brespectively faces, in the conveyance direction, the ink storage space13vof the housing13xof corresponding sub-tanks13B,13Y,13C,13M, but does not face, in the conveyance direction, the ink storage space13vof the housing13xadjacent to the corresponding housing13xin the scanning direction. That is, each of the side electrodes3bdoes not face the ink storage space13vof the housing13xadjacent to the housing13xfacing the corresponding side electrode3b.

A ground electrode3dis arranged between the two side electrodes3badjacent to each other in the scanning direction. Each ground electrode3dextends in the vertical direction and is arranged in a vertical region substantially the same as that of the two side electrodes3bsandwiching the ground electrode3din the scanning direction. In other words, each ground electrode3dand the two side electrodes3bsandwiching the ground electrode3din the scanning direction are substantially matching each other in the vertical direction.

In the housing13xof sub-tanks13B,13Y,13C,13M, each of the four side electrodes3cis provided at a side surface13xcfacing the side surface13xbin the conveyance direction. The side electrodes3care arranged at intervals in the scanning direction in the same manner as the side electrodes3b. The side electrode3cfaces the ink storage space13v, in the conveyance direction, of one corresponding housing13xout of the housings13xof the four sub-tanks13B,13Y,13C,13M. The side electrode3cdoes not face, in the conveyance direction, the ink storage spaces13vof the housings13xadjacent to the corresponding housing13xin the scanning direction. The side electrode3cand the side electrode3bsandwich the corresponding ink storage space13vin the conveyance direction.

As shown inFIG. 3, the side surface13xbis parallel to the vertical and scanning directions. On the other hand, the bottom surface13xais slanted relative to the horizontal direction so as to be lower toward the downstream side in the conveyance direction, i.e. the direction from the side surface13xcto the side surface13xb. Due to this, an angle θ1 (theta 1) formed by the bottom surface13xaand the side surface13xbis an acute angle. An end portion of the bottom surface13xaadjacent to the side surface13xb(i.e. the right end of the bottom surface13xainFIG. 3) is slanted relative to the horizontal direction and forms an acute angle with the side surface13xb.

In the same manner as above, the side electrode3bis parallel to the vertical and scanning direction. On the other hand, the bottom electrode3ais slanted relative to the horizontal direction so as to be lower toward the downstream side in the conveyance direction, i.e. the direction from the side electrode3cto the side electrode3b. An end portion of the bottom electrode3aadjacent to the side electrode3b(i.e. the right end of the bottom electrode3ainFIG. 3) is provided at the above-mentioned end portion of the bottom surface13xa. The end portion of the bottom electrode3aforms an acute angle with a surface that is parallel to the side electrode3band that extends upward from the tip end of the end portion of the bottom electrode3a.

A lower end3b1of each side electrode3bis located at a higher position than a lower end13v1of the corresponding ink storage space13v.

As shown inFIG. 5, the four cartridges40B,40Y,40C,40M are detachably mounted on respective ones of four storing chambers1zprovided in a cartridge holder1y. The four storing chambers1zare arranged in the scanning direction. Thus, when the four cartridges40B,40Y,40C,40M are mounted on the printer1, the housings40xof these cartridges are also arranged in the scanning direction.

As shown inFIGS. 3 and 5, each of the cartridges40B,40Y,40C,40M is provided with a bottom electrode4a, a side electrode4b, and a side electrode4c. The bottom electrode4a, the side electrode4b, and the side electrode4care individual electrodes with respect to each cartridge40B,40Y,40C,40M. In each of the cartridges40B,40Y,40C,40M, the side electrode4bis not electrically connected to the bottom electrode4a. The side electrode4cis electrically connected to the bottom electrode4a, but is not electrically connected to (that is, electrically isolated from) the side electrode4b.

The bottom electrode4ais provided at a bottom surface40xaof the housing40xof each cartridge40B,40Y,40C,40M. The bottom electrode4afaces substantially an entire region of the ink storage space40vof the corresponding one of the cartridges40B,40Y,40C,40M.

The electrode4bis provided at a side surface40xbof the housing40of each cartridge40B,40Y,40C,40M.

In the housing40xof each cartridge40B,40Y,40C,40M, the side electrode4cis provided at a side surface40xcfacing the side surface40xbin the scanning direction. The side electrodes4band4csandwich the corresponding ink storage space40vin the scanning direction.

Terminals40s1,40s2are provided at bottom and side walls which define each storing chamber1zin the cartridge holder1y. The terminal40s1is held at a ground potential and the terminal40s2is electrically connected to a capacitance measurement circuit for cartridge40s(refer toFIG. 6.). When cartridges40B,40Y,40C,40M are mounted in the storing chamber1z, the terminal40s1contacts the bottom electrodes4aand the terminal40s2contacts the side electrode4b, so that the bottom electrode4ais held at a ground potential, and the side electrode4bis electrically connected to a capacitance measurement circuit for cartridge40s.

As shown inFIG. 5, the side surface40xbis parallel to the vertical and conveyance directions, while the bottom surface40xais curved to be convex upward. Because of this, an angle θ2 (theta 2) formed by an end portion of the bottom surface40xaadjacent to the side surface40xb(i.e. the left end of the bottom surface40xainFIG. 5) and the side surface40xbis an acute angle. In other words, the above-described end portion of the bottom surface40xais slanted relative to the horizontal direction and forms an acute angle with the side surface40xb.

In the same manner as above, the side electrode4bis parallel to the vertical and conveyance directions, while the bottom electrode4ais curved to be convex upward. Because of this, an end portion in the bottom electrode4aadjacent to the side electrode4b(i.e. the left end inFIG. 5) is provided at the above-described end portion of the bottom surface40xaand forms an acute angle with a surface that is parallel to the side electrode4band that extends upward from the tip end of the above-described end portion of the bottom electrode4a.

A lower end4b1of the side electrode4bis located at a higher position than a lower end40v1of the corresponding ink storage space40v.

As shown inFIG. 1, the conveyance unit20conveys paper100in the conveyance direction. The conveyance unit20includes: a pair of conveyance rollers21arranged at the upstream side from the head12in the conveyance direction; and a pair of conveyance rollers22arranged at the downstream side from the head12. The pair of conveyance rollers21and22respectively includes a driving roller and a driven roller which are arranged to nip the paper100. When the driving roller rotates by a conveyance motor20m(refer toFIG. 6), the driving roller and the driven roller rotate in opposite directions to each other.

An image is formed on the paper100conveyed by the conveyance unit20in the conveyance direction with the ink ejected from the ejection port12xof the head12reciprocating in the scanning direction together with the carriage11.

The control unit50controls each part of the printer1. As shown inFIG. 6, the control unit50includes a CPU (Central Processing Unit)51, a ROM (Read Only Memory)52, and a RAM (Random Access Memory)53. The CPU51controls the carriage motor11m, the head driver12d, and the conveyance motor20m, in order to record an image on the paper100based on an image data transmitted from an external device (for example, a PC connected to the printer1). The ROM52stores programs to be executed by the CPU51, various fixed data, and the like. The RAM53temporarily stores data necessary for the CPU51to execute programs, such as image data.

The capacitance measurement circuit for sub-tank13smeasures a capacitance between the bottom electrode3aand each side electrode3b. The capacitance measurement circuit for sub-tank13sapplies a sine wave to each of the side electrodes3band transmits signals indicating voltage according to the magnitude of the above-described capacitance to the control unit50. The capacitance between the bottom electrode3aand each of the side electrodes3bvaries depending on the remaining amount of ink in the sub-tank. The ROM52stores data showing correlation of the remaining amount of ink in the sub-tank and the capacitance between the bottom electrode3aand each side electrode3b(a first correlation). The CPU51determines the remaining amount of ink in each sub-tank13B,13Y,13C,13M based on data showing the first correlation stored in the ROM52and the signal received from the capacitance measurement circuit for sub-tank13s, and executes suitable processing such as alarming for requesting exchange of the cartridges40B,40Y,40C,40M.

The capacitance measurement circuit for cartridge40smeasures a capacitance between the bottom electrode4aand the side electrode4bof each of the cartridges40B,40Y,40C,40M. The capacitance measurement circuit for cartridge40sapplies a sine wave to each of the side electrodes4bthrough the terminal40s2and transmits signals indicating voltage according to the magnitude of the above-described capacitance to the control unit50. The capacitance between the bottom electrode4aand the side electrode4bvaries depending on the remaining amount of ink in the cartridges. The ROM52stores data showing correlation of the remaining amount of ink in the cartridge and the capacitance between the bottom electrode4aand the side electrode4b(a second correlation). The CPU51determines the remaining amount of ink in each cartridge based on the data of the second correlation and the signals received from the capacitance measurement circuit for cartridge40s, and executes suitable processing such as alarming for requesting exchange of the cartridges40B,40Y,40C,40M.

As described above, according to the embodiment, in each sub-tank13B,13Y,13C,13M, the capacitance between the electrodes3aand3bis measured by providing an electrode (the bottom electrode3aand the side electrode3b) on each of the bottom surface13xaand the side surface13xbof the housing13x, not by providing an electrode on each of a pair of side surfaces of the housing13xfacing each other. In addition, in each cartridge40B,40Y,40C,40M, the capacitance between these electrodes4aand4bis measured by providing an electrode (the bottom electrode4aand the side electrode4b) on the bottom surface40xaand the side surface40xbof the housing40x(refer toFIG. 3), not by providing an electrode on each of a pair of side surfaces of the housing40xfacing each other. Thus, as shown in the below-described examples, as the rate of change of the capacitance to the remaining amount becomes larger in the vicinity of empty level, the detection accuracy of the remaining amount of ink can be improved.

In each sub-tank13B,13Y,13C,13M, an end portion in the bottom surface13xa(i.e. the right end of the bottom surface13xainFIG. 3) adjacent to the side surface13xbis slanted relative to the horizontal direction, and forms an acute angle with the side surface13xb. The end portion of the bottom electrode3a(i.e. the right end of the bottom electrode13ainFIG. 3) adjacent to the side electrode3bis provided at the above-described end portion of the bottom surface13xa. The end portion of the bottom electrode3aforms an acute angle with a surface that is parallel to the side electrode3band that extends upward from the tip end of the above-described end portion of the bottom electrode3a. In each cartridge40B,40Y,40C,40M, an end portion of the bottom surface40xa(i.e. the left end of the bottom surface40xa) adjacent to the side surface40xbis slanted relative to the horizontal direction and forms an acute angle with the side surface40xb. The end portion of the bottom electrode4a(i.e. the left end of the bottom electrode4ainFIG. 5) adjacent to the side electrode4bis provided at the above-described end portion of the bottom surface40xb, and forms an acute angle with a surface that is parallel to the side electrode4band that extends upward from the tip end of the above-described end portion of the bottom electrode4a. In this case, as shown in the below-described examples, the capacitance becomes larger in a region where the remaining amount is relatively large, compared with a case where a bottom surface is not slanted relative to the horizontal direction and a bottom electrode and a side electrode are perpendicular to each other. This suppresses enlarging the electrode for securing a capacitance required for detection of the remaining amount, and the electrodes and related components such as boards can be downsized. Moreover, as shown in the below-described example, the rate of change of the capacitance to the remaining amount becomes larger in the vicinity of empty level, compared with a case where a bottom surface is not slanted relative to the horizontal direction and a bottom electrode and a side electrode are perpendicular to each other. Thus, the detection accuracy of the remaining amount of ink can be improved.

In each sub-tank13B,13Y,13C,13M, the lower end3b1of the side electrode3bis located above the lower end13v1of the corresponding ink storage space13v(refer toFIG. 3). In each cartridge40B,40Y,40C,40M, the lower end4b1of the side electrode4bis located above the lower end40v1of the corresponding ink storage space40v(refer toFIG. 5). In this case, before the liquid level reaches the lower ends13v1,40v1of the ink storage space13v,40v, in other words, before reaching the empty level, the capacitance rapidly approaches near zero at the phase when the liquid level reaches the lower ends3b1,4b1of the side electrodes3b,4b. Accordingly, the detection accuracy of the remaining amount of ink can be improved in the vicinity of empty.

The housings13xfor the sub-tanks13B,13Y,13C,13M are arranged in the scanning direction (refer toFIG. 4). The bottom electrode3aextends in the scanning direction (i.e. parallel to the arrangement of the four housings13x), and the single bottom electrode3ais a common electrode for the four housings13x. The side electrode3bis an individual electrode for each of the housings13x. In this case, if either one of the bottom electrode3aand the side electrode3bextends along the arrangement direction of the four housings13x, such a common electrode can be easily formed. In addition, the use of the common electrode makes wiring for each electrode unnecessary, thereby facilitating manufacturing of the sub-tanks13B,13Y,13C,13M and downsizing the components around the electrodes.

The four side electrodes3bare arranged on a single board (substrate)3xin the scanning direction (i.e. the arrangement direction of the four housings13x) (refer toFIG. 4). This configuration suppresses complexity of wiring and facilitates the manufacturing, compared with the case of providing the individual electrode on an individual board.

Each of the four side electrodes3bdoes not face the ink storage space13vof the housing13xadjacent to the housing corresponding to that side electrode3bamong the housings13xof the four sub-tanks13B,13Y,13C,13M (refer toFIG. 4). Thus, in detecting the remaining amount of each sub-tank13B,13Y,13C,13M, a problem of being affected by an influence of the remaining amount of adjacent sub-tanks can be suppressed.

The ground electrode3dis provided between the adjacent two side electrodes3b,3b(refer toFIG. 4). The ground electrode3dsuppresses an influence of the remaining amount of ink in the adjacent sub-tank during the detection of the remaining amount in each sub-tank13B,13Y,13C,13M.

In the sub-tank13B,13Y,13C,13M, another side electrode3cwhich is electrically connected to the bottom electrode3abut not electrically connected to the side electrode3bis provided at one side surface13xc, among the plurality of side surfaces of the housing13x, facing the side surface13xbon which the side electrode3bis provided (refer toFIG. 3). In the cartridges40B,40Y,40C,40M, another side electrode4cwhich is electrically connected to the bottom electrode4abut not electrically connected to the side electrode4bis provided at one side surface40xc, among the plurality of side surfaces of the housing40x, facing the side surface40xbon which the side electrode4bis provided (refer toFIG. 5). As shown in the below-described example, this increases the rate of change of the capacitance to the remaining amount of ink in the region having a relatively large remaining amount, thereby improving the detection accuracy of the remaining amount, compared with the case where the other side electrodes3cand4care not provided.

Hereinafter, analysis results will be described with reference toFIGS. 7 and 8, regarding a relation between the remaining amount of ink and the capacitance in examples of this disclosure and comparative examples. The arrangement of electrodes in one liquid storage portion is different in each example.

In Example 1 of this disclosure, the bottom electrodes (i.e. the bottom electrodes3a,4aof the above embodiment) and the side electrodes (i.e. the side electrodes3b,4bof the above embodiment) are arranged on a rectangular parallelepiped liquid storage portion (i.e. having no slant or curve in the bottom and side surfaces), without providing the other side electrodes (i.e. the side electrodes3c,4cin the above-described embodiment).

In Example 2 of this disclosure, the bottom electrodes (i.e. the bottom electrodes3a,4aof the above embodiment), the side electrodes (i.e. the side electrodes3b,4bof the above embodiment), and the other side electrodes (i.e. the side electrodes3c,4cin the above-described embodiment) are arranged on a rectangular parallelepiped liquid storage portion (i.e. having no slant or curve in the bottom and side surfaces).

In Example 3 of this disclosure, the bottom electrode (i.e. the bottom electrode3aof the above embodiment) and the side electrode (i.e. the side electrode3bof the above embodiment) are arranged on a liquid storage portion having a slant in the bottom surface like the above-described sub-tank, without providing the other side electrode (i.e. the side electrode3cin the above-described embodiment).

In Example 4 of this disclosure, the bottom electrode (i.e. the bottom electrode4aof the above embodiment) and the side electrode (i.e. the side electrode4bof the above embodiment) are arranged on a liquid storage portion having a curve in the bottom surface like the above-described cartridge, without providing the other side electrode (i.e. the side electrode4cin the above-described embodiment).

In comparative example 1, an electrode is arranged on each of a pair of side surfaces facing each other in a rectangular parallelepiped liquid storage portion (i.e. having no slant or curve in the bottom and side surfaces).

In comparative example 2, two electrodes are arranged side by side in the horizontal direction on one side surface of a rectangular parallelepiped liquid storage portion (i.e. having no slant or curve in the bottom and side surfaces).

In comparative example 3, an electrode is arranged on each of two side surfaces connecting to each other (intersecting each other) in a rectangular parallelepiped liquid storage portion (having no slant or curve in the bottom and side surfaces).

As shown inFIG. 7, the rate of change of the capacitance relative to the remaining amount in Comparative examples 1-3 increases proportionally, while the rate of change of the capacitance relative to the remaining amount in Examples 1 and 2 of this disclosure is larger in the vicinity of empty. Thus, it can be said that Examples 1 and 2 of this disclosure can improve the detection accuracy of the remaining amount in the vicinity of empty compared with Comparative examples 1-3.

FIG. 7shows that Example 2 of this disclosure (i.e. the configuration having the other side electrode) has a larger rate of change of the capacitance relative to the remaining amount than that of Example 1 of this disclosure (i.e. the configuration without the other side electrode). Thus, it can be said that, when the other side electrode is provided, the detection accuracy of the remaining amount can be improved in the region having a relatively large remaining amount, compared with the configuration without the other side electrode.

FIG. 8shows that Example 3 of this disclosure (i.e. the configuration having slant in the bottom surface) and Example 4 of this disclosure (i.e. the configuration having curve in the bottom surface) have a larger capacitance in the region of a relatively large remaining amount, and also have a larger rate of change of the capacitance relative to the remaining amount in the vicinity of empty, compared with Example 1 of this disclosure (i.e. the configuration without slant or curve in the bottom surface). Thus, it can be said that, according to Examples 3 and 4 of this disclosure (i.e. a configuration where an end portion of the bottom surface adjacent to one side surface having a side electrode thereon slants relative to the horizontal direction and forms an acute angle with the side surface; an end portion of the bottom electrode adjacent to the side electrode is provided at the above-described end portion of the bottom surface and forms an acute angle with a surface that is parallel to the side electrode and that extends upward from the tip end of the end portion of the bottom electrode), the capacitance is larger in a region having a relatively large remaining amount and the detection accuracy of the remaining amount can be improved in the vicinity of empty, compared with Example 1 of this disclosure (a configuration where the bottom surface is not slanted relative to the horizontal direction and the bottom electrode and the side electrode are perpendicular).

The liquid storage portion provided in the liquid ejecting apparatus is not limited to an exchangeable tank (i.e. cartridge). The liquid storage portion may be a refillable tank to which liquid can be refilled.

The number of the liquid storage portions provided in the liquid ejecting apparatus may be any number of one or more. For example, four sub-tanks (or cartridges) are used as a set in the above-described embodiments. However, two sub-tanks (or cartridges) may be used as a set. Alternatively, only a single sub-tank and/or a single cartridge may be provided.

When a plurality of liquid storage portions is provided in the liquid ejecting apparatus, an electrode and a circuit of this disclosure may be provided to at least one of the plurality of the liquid storage portions.

The method for measuring the capacitance by using a circuit is not limited to the method described in the above embodiment. Any method (for example, a bridge method, a method using a resonance frequency, a method using a charging time constant, and a method using a flying capacitor) may be used.

The bottom surface may not be necessarily slanted relative to the horizontal direction, and the bottom electrode and the side electrode may be perpendicular to each other.

The lower end of the side electrode may be located at the same height as the lower end of the liquid storage space, or may be located at a lower position than the lower end of the liquid storage space.

The side electrode may be a common electrode, and the bottom electrode may be individual electrodes.

The plurality of individual electrodes may not be necessarily arranged on a single board.

The ground electrodes may not be necessarily provided between a plurality of individual electrodes.

The other side electrode may be omitted.

In the above-described embodiment, the bottom electrode and the side electrode are provided on the housing of the sub-tanks and the cartridges. Alternatively, the bottom electrode and the side electrode may be provided on surfaces (walls) of the liquid ejecting apparatus on which the sub-tanks and the cartridges are arranged. That is, the bottom electrode and the side electrode may be provided at the liquid ejecting apparatus.

For example, inFIG. 5, the bottom electrode4amay be provided on at a bottom wall of the cartridge holder1yand configured to face or contact the bottom surface40xaof the cartridge40when the cartridge40is mounted on the cartridge holder1y. Similarly, the side electrode4bmay be provided on at a side wall of the cartridge holder1yand configured to face or contact the side surface40xbof the cartridge40when the cartridge40is mounted on the cartridge holder1y.

The liquid stored in the liquid storage portion is not limited to ink. The liquid may be any kind of liquid (for example, a processing liquid for agglutinating or precipitating components in ink).

This disclosure is applicable not only to a color printer but also to a monochromatic printer. This disclosure is applicable not only to a printer but also to a facsimile machine, a photocopier, a multi-function peripheral, and so on.