Patent Description:
There is known an image recording device comprising a head and a carriage mounted with the head, that discharges ink from nozzles of the head when the carriage moves in a predetermined direction. The image recording device has an ink supply device that supplies ink to the head from a reservoir of the ink. In the case of a plurality of kinds of inks is supplied, the ink supply device has a plurality of ink channels provided between a plurality of the reservoirs and the head.

In Patent Literature <NUM>, there is described a printer comprising: a head having four kinds of nozzles respectively discharging four colors of inks; and a cap collectively covering the four kinds of nozzles. In this printer, the four colors of inks are respectively supplied to four sub-tanks from four cartridges, and four ink channels are employed to respectively supply the four colors of inks to the head from the four sub-tanks. <CIT> discloses a pressure adjustment apparatus and image forming apparatus, and pressure adjustment method and liquid remaining amount determination method. <CIT> discloses a liquid supply apparatus and liquid ejection apparatus. <CIT> discloses a liquid ejecting apparatus and method of replacing liquid ejecting head. <CIT> discloses an inkjet printer. <CIT> discloses an inkjet printer.

In the printer described in Patent Literature <NUM>, there is performed a so-called initial introduction where the four colors of inks are respectively initially introduced into the four ink channels by a suction pressure being applied from the head side. In this printer, ink is supplied employing a water head difference between the cartridge and the sub-tank. Therefore, as much ink will flow into the sub-tank from the cartridge as an amount of ink in the sub-tank that has flowed to the head side due to the suction pressure.

Sometimes, there is a difference in resistance between the four ink channels connecting the four sub-tanks and the head. In such a case, when the previously-mentioned initial introduction is performed, an amount of ink flowing to the head side from the sub-tank through a channel having a small channel resistance will increase, and an amount of ink flowing to the head side from the sub-tank through a channel having a large channel resistance will decrease. There will thus occur a difference in ink introduction amounts between the plurality of ink channels. This will result in that when, for example, suction time is set so that a sufficient amount of ink will flow to the head side through the channel having a large channel resistance, an excessive amount of ink will flow to the head side through the channel having a small channel resistance.

The present invention, which was made in view of the above-described circumstances, has an object of providing a means by which difference in liquid amounts flowing into a head through a plurality of channels by suction becomes smaller.

The present invention results in difference in liquid amounts flowing into a head through a plurality of channels by suction becoming smaller.

A printer <NUM> (one example of an image recording device) and ink supply unit <NUM> (one example of a liquid supply device) according to an embodiment of the present invention will be described below. Note that the embodiment described below is merely one example of the present invention, and it goes without saying that the embodiment of the present invention can be appropriately altered in a range not altering the gist of the present invention. In the description below, progression from a start point to an end point of an arrow will be expressed as orientation, and coming and going on a line connecting a start point and an end point of an arrow will be expressed as direction. Moreover, an up-down direction <NUM> is defined with reference to a state of the printer <NUM> having been usably installed (the state of <FIG>), a front-rear direction <NUM> is defined assuming a surface provided with a discharge port <NUM> to be a front surface, and a left-right direction <NUM> is defined looking at the printer <NUM> from the front. The up-down direction <NUM>, the front-rear direction <NUM>, and the left-right direction <NUM> are orthogonal to each other.

The printer <NUM> depicted in <FIG> is an image recording device that records an image on a sheet S (one example of a recording medium) by an inkjet recording system. The sheet S is a long paper sheet that has been wound into a roll shape. In order for the sheet S to be mounted in the printer <NUM>, a winding center of the sheet S has a through-hole formed therein. A recording objective medium may be the likes of a seal paper, fan-fold paper, cut paper, or a fabric.

The printer <NUM> comprises a housing <NUM> of substantially rectangular parallelepiped shape. The housing <NUM> has a size enabling it to be mounted on a tabletop, on a floor, or in a rack, and so on. Located in a front wall <NUM> of the housing <NUM> is the discharge port <NUM> which is slit-like and extends in the left-right direction <NUM>. The sheet S that has been recorded with an image by the printer <NUM> is discharged from the discharge port <NUM>. The discharged sheet S is wound by a winding device (not depicted) fitted to the printer <NUM>, for example.

As depicted in <FIG>, the printer <NUM> comprises the following within the housing <NUM>, namely, a holder <NUM>, a tensioner <NUM>, a conveying roller pair <NUM>, a discharging roller pair <NUM>, a platen <NUM>, a cartridge holder <NUM>, a carriage <NUM>, a head <NUM>, and the ink supply unit <NUM> (see <FIG>). The head <NUM> is installed in the carriage <NUM>. The cartridge holder <NUM> is fitted with a cartridge <NUM> that stores ink (one example of a liquid). As depicted in <FIG>, the printer <NUM> further comprises the following within the housing <NUM>, namely, two guide rails <NUM>, <NUM> and a cap <NUM>. As depicted in <FIG>, the printer <NUM> further comprises the following within the housing <NUM>, namely, a controller <NUM>, a motor for holder drive <NUM>, a motor for conveyance <NUM>, a motor for carriage drive <NUM>, and a motor for cap drive <NUM>. The printer <NUM> may further comprise a wipe unit, various kinds of motors, various kinds of sensors, and so on, besides the above-mentioned elements.

Located inside the housing <NUM> are a pair of side frames (not depicted) that extend in the up-down direction <NUM> and the front-rear direction <NUM>. The holder <NUM> has a rotating shaft <NUM> that supports the sheet S. The rotating shaft <NUM> extends in the left-right direction <NUM> and has its two ends fixed to the side frames. Motive power of the motor for holder drive <NUM> (see <FIG>) is transmitted to the rotating shaft <NUM>. This motive power causes the holder <NUM> to rotate in a circumferential direction of the rotating shaft <NUM>. In <FIG>, a rotating direction of the holder <NUM> is counter-clockwise. Rotation of the holder <NUM> causes a roll body supported by the holder <NUM> to rotate too. The sheet S is led out upwardly from a rear end of the roll body and guided to the tensioner <NUM> as a result of the conveying roller pair <NUM> and discharge roller pair <NUM> rotating.

The tensioner <NUM>, the conveying roller pair <NUM>, and the discharge roller pair <NUM> each extend in the left-right direction <NUM> between the side frames and are installed in a manner enabling them to rotate in a circumferential direction of their rotational axes parallel to the left-right direction <NUM>. The tensioner <NUM> is applied with a biasing force in a rearward orientation by a biasing member such as a spring. The tensioner <NUM> abuts on the sheet S led out from the roll body and thereby guides the sheet S in such a manner that the sheet S curves frontwards.

The conveying roller pair <NUM> include a drive roller <NUM> and a pinch roller <NUM>, and are located forward of the tensioner <NUM>. The discharge roller pair <NUM> include a drive roller <NUM> and a pinch roller <NUM>, and are located further forward than the conveying roller pair <NUM>. Lower end positions of the drive rollers <NUM>, <NUM> substantially coincide with an upper end position of the tensioner <NUM> in the up-down direction <NUM>. The pinch roller <NUM> abuts from below on the drive roller <NUM>. The pinch roller <NUM> abuts from below on the drive roller <NUM>.

Motive power of the motor for conveyance <NUM> (see <FIG>) is transmitted to the drive rollers <NUM>, <NUM>. This motive power causes the drive rollers <NUM>, <NUM> to rotate. As a result, the drive rollers <NUM>, <NUM> convey the sheet S in a conveying orientation <NUM> while nipping the sheet S between the drive roller <NUM> and the pinch roller <NUM> as well as between the drive roller <NUM> and the pinch roller <NUM>. In the present embodiment, the conveying orientation <NUM> is a frontward orientation. The motor for conveyance <NUM>, the conveying roller pair <NUM>, and the discharge roller pair <NUM> function as a conveyer (conveying unit) that conveys the sheet S to which ink discharged from the head <NUM> lands.

The platen <NUM> is fitted to the side frames at a position between the conveying roller pair <NUM> and discharge roller pair <NUM> in the front-rear direction <NUM>. The platen <NUM> extends in the left-right direction <NUM> between the side frames, and includes a supporting surface <NUM> for the sheet S, that extends in the front-rear direction <NUM> and the left-right direction <NUM>. The supporting surface <NUM> is an upper end surface of the platen <NUM>. A position in the up-down direction <NUM> of the supporting surface <NUM> substantially coincides with the upper end position of the tensioner <NUM>. The platen <NUM> may be a sucking platen that sucks the sheet S onto the supporting surface <NUM>.

As depicted in <FIG>, the guide rails <NUM>, <NUM> extend in the left-right direction <NUM> parallelly to each other. Positions in the up-down direction <NUM> of the guide rails <NUM>, <NUM> are the same. The guide rail <NUM> is located rearward of the guide rail <NUM> in the front-rear direction <NUM>. Both ends of the guide rails <NUM>, <NUM> are fixed to the side frames. The carriage <NUM> is supported by the guide rails <NUM>, <NUM>. Motive power of the motor for carriage drive <NUM> (see <FIG>) is transmitted to a carriage drive mechanism (not depicted). The carriage <NUM> moves in the left-right direction <NUM> due to action of the carriage drive mechanism, in a state of being supported by the guide rails <NUM>, <NUM>.

As depicted in <FIG>, the head <NUM> is installed in the carriage <NUM>. A lower surface of the head <NUM> is referred to as a nozzle surface <NUM>. A plurality of nozzles <NUM> each configured to discharge ink is located in the nozzle surface <NUM>. The cartridge <NUM> fitted to the cartridge holder <NUM>, and the head <NUM> are connected via the ink supply unit <NUM> (see <FIG>). Ink stored in the cartridge <NUM> is supplied to the head <NUM> via the ink supply unit <NUM>. While the carriage <NUM> is moving in the left-right direction <NUM>, ink that has been supplied to the head <NUM> is discharged from the nozzles <NUM>. As a result, image recording is performed on the sheet S.

As depicted in <FIG>, the controller <NUM> has a CPU <NUM>, a ROM <NUM>, a RAM <NUM>, an EEPROM <NUM>, and an ASIC <NUM>. The ROM <NUM> stores the likes of various kinds of data required in operation of the controller <NUM>. The RAM <NUM> is a working memory of the CPU <NUM>. The EEPROM <NUM> stores the likes of a control program executed by the CPU <NUM>. Prior to image recording being executed by the printer <NUM>, the control program stored in the EEPROM <NUM> is copied to the RAM <NUM>. The CPU <NUM> executes the control program stored in the RAM <NUM>. As a result, the controller <NUM> executes ink automatic supply processing, image recording processing, and initial introduction processing that will be described later. The controller <NUM> is one example of a controller.

The controller <NUM> is electrically connected to the motor for holder drive <NUM>, the motor for conveyance <NUM>, the motor for carriage drive <NUM>, the motor for cap drive <NUM>, a motor for elevator member drive <NUM>, a motor for pump drive <NUM>, and the head <NUM>, via the ASIC <NUM>. The motor for holder drive <NUM>, the motor for conveyance <NUM>, the motor for carriage drive <NUM>, the motor for cap drive <NUM>, the motor for elevator member drive <NUM>, and the motor for pump drive <NUM> rotate according to control from the controller <NUM>, and generate motive power. The head <NUM> discharges ink onto the sheet S conveyed on the platen <NUM>, according to control from the controller <NUM>.

The holder <NUM> rotates due to motive power from the motor for holder drive <NUM>. The drive rollers <NUM>, <NUM> rotate due to motive power from the motor for conveyance <NUM>. The sheet S is conveyed in the conveying orientation <NUM> due to motive power from the motor for conveyance <NUM>. The carriage <NUM> moves in the left-right direction <NUM> due to motive power from the motor for carriage drive <NUM>. The cap <NUM> moves in the up-down direction <NUM> between a relatively high covering position and a relatively low separated position, due to motive power from the motor for cap drive <NUM>. An elevator member <NUM> (see <FIG>; details described later) moves in the up-down direction <NUM> between a relatively high abutting position and a relatively low non-abutting position, due to motive power from the motor for elevator member drive <NUM>. A pump <NUM> (see <FIG>), which is driven by motive power from the motor for pump drive <NUM>, provides a suction pressure to a channel connected to the pump <NUM>. Note that some of the motor for holder drive <NUM>, the motor for conveyance <NUM>, the motor for carriage drive <NUM>, the motor for cap drive <NUM>, the motor for elevator member drive <NUM>, and the motor for pump drive <NUM> may be realized by a common motor.

As depicted in <FIG>, the platen <NUM>, which has a shape long in the left-right direction <NUM>, is located below the carriage <NUM> in the up-down direction <NUM> (see <FIG>). A left end of the platen <NUM> is located close to left ends of the guide rails <NUM>, <NUM> in the left-right direction <NUM>. A right end of the platen <NUM> is located further to the right than centers of the guide rails <NUM>, <NUM> in the left-right direction <NUM>. The cap <NUM> is located to the right of the platen <NUM> in the left-right direction <NUM>. While image recording is being executed by the printer <NUM>, the carriage <NUM> moves in the left-right direction <NUM> within a range of the platen <NUM>. While image recording is not being executed by the printer <NUM>, the carriage <NUM> is located in a position where the head <NUM> faces the cap <NUM> (hereafter, referred to as a standby position).

As depicted in <FIG>, the cap <NUM> includes: a nozzle cap <NUM> configured to cover the nozzle surface <NUM> of the head <NUM>; and an exhaust cap <NUM> configured to cover an exhaust port surface <NUM> of an exhaust portion <NUM> (details of which will be described later). When the carriage <NUM> is located in the standby position, the cap <NUM> is located in the covering position. At this time, the nozzle cap <NUM> covers the nozzle surface <NUM> of the head <NUM>, and the exhaust cap <NUM> covers the exhaust port surface <NUM> of the exhaust portion <NUM>. When the carriage <NUM> is located in a position other than the standby position, the cap <NUM> is located in the separated position. At this time, the nozzle cap <NUM> does not cover the nozzle surface <NUM>, and the exhaust cap <NUM> does not cover the exhaust port surface <NUM>. In this way, the cap <NUM> has a function of covering the nozzle surface <NUM> and the exhaust port surface <NUM> in a time period in which image recording is not executed.

The ink supply unit <NUM> of the printer <NUM> will be described with reference to <FIG>. The cartridge holder <NUM> (see <FIG>) is installed with four cartridges 51b, 51c, <NUM>, 51y that respectively store black, cyan, magenta, and yellow inks. The ink supply unit <NUM> comprises the cartridges 51b, 51c, <NUM>, 51y, four valves 52b, 52c, <NUM>, 52y, four sub-tanks 53b, 53c, <NUM>, 53y, eight sensors 54b, 54c, <NUM>, 54y, 55b, 55c, <NUM>, 55y, the head <NUM>, the pump <NUM>, and the controller <NUM>.

The inks stored in the cartridges 51b, 51c, <NUM>, 51y, which are so-called latex inks, contain a pigment, resin fine particles, and an additive. The ink has a viscosity suitable for evenly dispersing the pigment and the resin fine particles. The pigment represents the color of the ink. The resin fine particles, which are for causing the pigment to adhere to the sheet S, are of a synthetic resin whose glass transition temperature is exceeded by heating of a heater (not depicted), for example. Note that the printer <NUM> may be installable with at least two cartridges, and may have at least two sub-tanks.

An ink channel 56b connects the cartridge 51b and the sub-tank 53b. An ink channel 56c connects the cartridge 51c and the sub-tank 53c. An ink channel <NUM> connects the cartridge <NUM> and the sub-tank <NUM>. An ink channel 56y connects the cartridge 51y and the sub-tank 53y. An ink channel 57b connects the sub-tank 53b and the head <NUM>. An ink channel 57c connects the sub-tank 53c and the head <NUM>. An ink channel <NUM> connects the sub-tank <NUM> and the head <NUM>. An ink channel 57y connects the sub-tank 53y and the head <NUM>.

The ink stored in the cartridge 51b is supplied to the sub-tank 53b via the ink channel 56b. The sub-tank 53b stores the ink that has been supplied from the cartridge 51b. The ink stored in the sub-tank 53b is supplied to the head <NUM> via the ink channel 57b. Similarly, the ink stored in the cartridge 51c is supplied to the head <NUM> via the ink channel 56c, the sub-tank 53c, and the ink channel 57c. The ink stored in the cartridge <NUM> is supplied to the head <NUM> via the ink channel <NUM>, the sub-tank <NUM>, and the ink channel <NUM>. The ink stored in the cartridge 51y is supplied to the head <NUM> via the ink channel 56y, the sub-tank 53y, and the ink channel 57y.

The sub-tanks 53b, 53c, <NUM>, 53y are flexible. Outer shapes of the sub-tanks 53b, 53c, <NUM>, 53y change between an expanded (swollen) state and a contracted (shrunken) state depending on an amount of ink stored therein. The sub-tank 53b is located in a lower position than the cartridge 51b. Supply of ink from the cartridge <NUM>1b to the sub-tank 53b is performed by water head difference. Supply of ink from the sub-tank 53b to the head <NUM> is initially performed by sucking the ink from the head <NUM> side by the pump <NUM>. Subsequently, the same amount of ink as ink that has been discharged from the head <NUM> is supplied to the head <NUM> from the sub-tank 53b. Supply of ink from the sub-tanks 53c, <NUM>, 53y to the head <NUM> is performed by a similar method too.

The black ink can flow into the head <NUM> through the ink channel 57b from the sub-tank 53b, the cyan ink can flow into the head <NUM> through the ink channel 57c from the sub-tank 53c, the magenta ink can flow into the head <NUM> through the ink channel <NUM> from the sub-tank <NUM>, and the yellow ink can flow into the head <NUM> through the ink channel 57y from the sub-tank 53y. The ink supply unit <NUM> has four ink channels (an ink channel for black ink, an ink channel for cyan ink, an ink channel for magenta ink, and an ink channel for yellow ink) between the cartridges 51b, 51c, <NUM>, 51y and the head <NUM>.

The sensors 54b, 55b, which are located on an inside or an outside of the sub-tank 53b, detect ink amount of the sub-tank 53b. The sensor 54b outputs a sensor signal Sb1 indicating that ink amount of the sub-tank 53b (amount of the ink in the sub-tank 53b) is a threshold value TH1 or more. The sensor 55b outputs a sensor signal Sb2 indicating that ink amount of the sub-tank 53b is less than a threshold value TH2. Similarly, the sensors 54c, <NUM>, 54y respectively output sensor signals Sc1, Sm1, Sy1 indicating that ink amounts of the sub-tanks 53c, <NUM>, 53y are the threshold values TH1 or more. The sensors 55c, <NUM>, 55y respectively output sensor signals Sc2, Sm2, Sy2 indicating that ink amounts of the sub-tanks 53c, <NUM>, 53y are less than the threshold values TH2.

Each of sensors 54b, 54c, <NUM>, 54y, 55b, 55c, <NUM>, 55y detects ink amount of one of sub-tanks 53b, 53c, <NUM>, 53y corresponding thereto by an arbitrary method. Each sensor may detect ink amount of the one of the sub-tanks 53b, 53c, <NUM> ,53y corresponding thereto by optically detecting change in outer shape of the one of the sub-tanks 53b, 53c, <NUM>, 53y corresponding thereto, for example. Each sensor may detect ink amount of the one of the sub-tanks 53b, 53c, <NUM>, 53y corresponding thereto by a publicly known float system, prism system, or electrode system. The threshold values TH2 employed in comparison with ink amounts by the sensors 55b, 55c, <NUM>, 55y are respectively smaller than the threshold values TH1 employed in comparison with ink amounts by the sensors 54b, 54c, <NUM>, 54y. The threshold values employed in comparison with ink amounts by the sensors 54b, 54c, <NUM>, 54y are not necessarily all the same value, and there may be threshold value(s) whose value(s) is different from a value of the other threshold value of the four threshold values. The threshold values employed in comparison with ink amounts by the sensors 55b, 55c, <NUM>, 55y are not necessarily all the same value, and there may be threshold value(s) whose value(s) is different from a value of the other threshold value of the four threshold values.

The controller <NUM> is inputted with the sensor signals Sb1, Sc1, Sm1, Sy1, Sb2, Sc2, Sm2, Sy2 that have been respectively outputted from the sensors 54b, 54c, <NUM>, 54y, 55b, 55c, <NUM>, 55y. The controller <NUM> outputs a control signal Vb of the valve 52b, a control signal Vc of the valve 52c, a control signal Vm of the valve <NUM>, and a control signal Vy of the valve 52y, based on the sensor signals the controller has been inputted with. The control signals Vb, Vc, Vm, Vy are binary signals for switching states of the valves <NUM> between an open state and a closed state.

The valve 52b, which is located on the ink channel 56b, opens and closes the ink channel 56b according to the control signal Vb. The valve 52c, which is located on the ink channel 56c, opens and closes the ink channel 56c according to the control signal Vc. The valve <NUM>, which is located on the ink channel <NUM>, opens and closes the ink channel <NUM> according to the control signal Vm. The valve 52y, which is located on the ink channel 56y, opens and closes the ink channel 56y according to the control signal Vy.

The ink channel 57b branches on its head <NUM> side into a portion reaching the nozzle <NUM> of the head <NUM> and portion reaching an exhaust port <NUM> of the exhaust portion <NUM>. An inner space of the nozzle cap <NUM> is connected to a first end of a switching portion <NUM>. An inner space of the exhaust cap <NUM> is connected to a second end of the switching portion <NUM>. A third end of the switching portion <NUM> is connected to one end of the pump <NUM>. A waste liquid tank <NUM> is located on the other end side of the pump <NUM>. The switching portion <NUM> switches which of the inner space of the nozzle cap <NUM> and inner space of the exhaust cap <NUM> the pump <NUM> is to be connected to, by control from the controller <NUM>. The pump <NUM> is one example of a suction mechanism applying a suction pressure to the ink channels 57c, 57b, <NUM>, 57y from the head <NUM> side.

As depicted in <FIG>, a buffer <NUM> having an inner space (not depicted) configured to store a small amount of ink, is located in an upper portion of the head <NUM>. The buffer <NUM> and the head <NUM> are connected by a coupling portion <NUM> extending in the up-down direction <NUM>. The exhaust portion <NUM>, which is of rectangular parallelepiped shape, is located on a right side of the buffer <NUM>. The exhaust port surface <NUM>, which is a lower surface of the exhaust portion <NUM>, is located in a higher position than the nozzle surface <NUM> in the up-down direction <NUM>. Four exhaust ports <NUM> are located in the exhaust port surface <NUM>. The four exhaust ports <NUM> are aligned at a predetermined interval in the front-rear direction <NUM>.

Four ink inflow ports <NUM> are located in an upper surface of the buffer <NUM>. The four ink inflow ports <NUM> are respectively connected to ink tubes (not depicted) configuring parts of the ink channels 57b, 57c, <NUM>, 57y. Four coupling channels <NUM> are located in a rear portion of the coupling portion <NUM>. The four coupling channels <NUM> extend in the up-down direction <NUM> and are aligned in the left-right direction <NUM>. Four connecting portions <NUM> are located in an upper portion of the exhaust portion <NUM>. The four ink inflow ports <NUM> are respectively connected to the four coupling channels <NUM> via four ink channels (not depicted) in the buffer <NUM>. Ink that has reached the ink inflow port <NUM> passes along the ink channels in the buffer <NUM> and coupling channels <NUM> to reach the head <NUM> and be discharged in a downward orientation from the nozzles <NUM> located in the nozzle surface <NUM>.

The four coupling channels <NUM> are respectively connected to the four connecting portions <NUM> too, via another four ink channels (not depicted) in the buffer <NUM>. The four connecting portions <NUM> are respectively connected to the four exhaust ports <NUM> via four channels along which mainly gas flows. As depicted in <FIG>, the channel connecting the connecting portion <NUM> and the exhaust port <NUM> has a diameter enlarged portion <NUM>. A spring <NUM> and valve body <NUM> are located in an inner space of the diameter enlarged portion <NUM>. The valve body <NUM> has a main body portion <NUM> and a projecting portion <NUM>. The main body portion <NUM>, which has an outer diameter substantially equal to an inner diameter of the diameter enlarged portion <NUM>, is located within the diameter enlarged portion <NUM>. The projecting portion <NUM>, which has an outer diameter smaller than the inner diameter of the diameter enlarged portion <NUM>, projects downwardly toward the exhaust port <NUM> from the diameter enlarged portion <NUM>. The spring <NUM>, which is located above the valve body <NUM>, biases the valve body <NUM> in a downward orientation. In a normal state, the main body portion <NUM> is pressed onto a bottom surface of the diameter enlarged portion <NUM> by action of the spring <NUM>, and the four exhaust ports <NUM> are in a closed state.

Located below the exhaust cap <NUM> is the elevator member <NUM>. The elevator member <NUM> has four abutting portions <NUM>. The four abutting portions <NUM>, which have shapes projecting in an upward orientation, are aligned at a predetermined interval in the front-rear direction <NUM>. Four through-holes are located in a bottom surface of the exhaust cap <NUM>. The four through-holes are aligned at a predetermined interval in the front-rear direction <NUM>. The interval of the four exhaust ports <NUM>, the interval of the four abutting portions <NUM>, and the interval of the four through-holes of the exhaust cap <NUM> are all the same. The four abutting portions <NUM> respectively penetrate the four through-holes of the exhaust cap <NUM>.

As described above, the elevator member <NUM> is capable of moving in the up-down direction <NUM> between the relatively high abutting position and the relatively low non-abutting position, due to motive power from the motor for elevator member drive <NUM>. The elevator member <NUM> is capable of moving in the up-down direction <NUM>, independently of the exhaust cap <NUM>. When the carriage <NUM> is located in the standby position and the elevator member <NUM> is located in the abutting position, the four abutting portions <NUM> respectively abut on the four projecting portions <NUM>. At this time, the four valve bodies <NUM> move in an upward orientation against a restoring force of the spring <NUM>, and separate from the bottom surface of the diameter enlarged portion <NUM>. Hence, the four exhaust ports <NUM> attain an open state.

When the carriage <NUM> is located in the standby position and the elevator member <NUM> is located in the non-abutting position, the exhaust ports <NUM> attain a closed state. By the inner space of the nozzle cap <NUM> and the pump <NUM> being connected by the switching portion <NUM>, and the pump <NUM> thereupon being driven under such condition, the ink channels 57b, 57c, <NUM>, 57y are provided with a suction pressure from the head <NUM> side. As a result, ink and gas in the ink channels 57b, 57c, <NUM>, 57y is discharged from the nozzles <NUM>. The ink that has been discharged from the nozzles <NUM> is stored in the waste liquid tank <NUM>.

When the carriage <NUM> is located in the standby position and the elevator member <NUM> is located in the abutting position, the exhaust ports <NUM> attain an open state. By the inner space of the exhaust cap <NUM> and the pump <NUM> being connected by the switching portion <NUM>, and the pump <NUM> thereupon being driven under such condition, the ink channels 57b, 57c, <NUM>, 57y are provided with a suction pressure from the head <NUM> side (specifically, from the exhaust portion <NUM>). As a result, ink and gas in the ink channels 57b, 57c, <NUM>, 57y is discharged from the discharge ports <NUM>. Mainly gas is discharged from the discharge ports <NUM>.

The controller <NUM> continuously or always executes the ink automatic supply processing depicted in <FIG>. The controller <NUM> executes the initial introduction processing depicted in <FIG> during initial setting of the printer <NUM>. The controller <NUM> executes the image recording processing depicted in <FIG> after initial setting of the printer <NUM> has been completed. The controller <NUM> executes image recording processing and ink automatic supply processing in parallel (or time divisionally). The controller <NUM> stops ink automatic supply processing while initial introduction processing is being executed.

The controller <NUM> repeatedly executes steps S11-S26 in the ink automatic supply processing depicted in <FIG>. The controller <NUM> determines whether the sensor signal Sb2 (the signal indicating that ink amount of the sub-tank 53b is less than the threshold value TH2) has been received from the sensor 55b (step S11). In response to having determined the sensor signal Sb2 to have been received (step S11: Yes), the controller <NUM> opens the valve 52b (step S12). Next, the controller <NUM> determines whether the sensor signal Sb1 (the signal indicating that ink amount of the sub-tank 53b is the threshold value TH1 or more) has been received from the sensor 54b (step S13). In response to having determined the sensor signal Sb1 to have been received (step S13: Yes), the controller <NUM> closes the valve 52b (step S14).

Next, the controller <NUM> determines whether the sensor signal Sc2 (the signal indicating that ink amount of the sub-tank 53c is less than the threshold value TH2) has been received from the sensor 55c (step S15). In response to having determined the sensor signal Sc2 to have been received (step S15: Yes), the controller <NUM> opens the valve 52c (step S16). Next, the controller <NUM> determines whether the sensor signal Sc1 (the signal indicating that ink amount of the sub-tank 53c is the threshold value TH1 or more) has been received from the sensor 54c (step S17). In response to having determined the sensor signal Sc1 to have been received (step S17: Yes), the controller <NUM> closes the valve 52c (step S18).

Next, the controller <NUM> determines whether the sensor signal Sm2 (the signal indicating that ink amount of the sub-tank <NUM> is less than the threshold value TH2) has been received from the sensor <NUM> (step S19). In response to having determined the sensor signal Sm2 to have been received (step S19: Yes), the controller <NUM> opens the valve <NUM> (step S20). Next, the controller <NUM> determines whether the sensor signal Sm1 (the signal indicating that ink amount of the sub-tank <NUM> is the threshold value TH1 or more) has been received from the sensor <NUM> (step S21). In response to having determined the sensor signal Sm1 to have been received (step S21: Yes), the controller <NUM> closes the valve <NUM> (step S22).

Next, the controller <NUM> determines whether the sensor signal Sy2 (the signal indicating that ink amount of the sub-tank 53y is less than the threshold value TH2) has been received from the sensor 55y (step S23). In response to having determined the sensor signal Sy2 to have been received (step S23: Yes), the controller <NUM> opens the valve 52y (step S24). Next, the controller <NUM> determines whether the sensor signal Sy1 (the signal indicating that ink amount of the sub-tank 53y is the threshold value TH1 or more) has been received from the sensor 54y (step S25). In response to having determined the sensor signal Sy1 to have been received (step S25: Yes), the controller <NUM> closes the valve 52y (step S26).

The controller <NUM> repeatedly executes steps S31-S41 in the image recording processing depicted in <FIG>. At a timepoint of the controller <NUM> executing the step S31, the carriage <NUM> is located in the standby position, and the cap <NUM> is located in the covering position. The nozzle surface <NUM> of the head <NUM> is covered by the nozzle cap <NUM>.

The controller <NUM> receives an image recording instruction from an operating unit (not depicted) (step S31). Specifically, the controller <NUM> waits in the step S31 until it receives the image recording instruction. Upon receiving the image recording instruction in the step S31, the controller <NUM> closes the four valves 52b, 52c, <NUM>, 52y (step S32). Next, the controller <NUM> moves the cap <NUM> in a downward orientation from the covering position to the separated position (step S33).

Next, the controller <NUM> moves the carriage <NUM> in a leftward orientation to a recording start position (step S34). The recording start position is a predetermined position that the carriage <NUM> faces the platen <NUM>. Next, the controller <NUM> conveys the sheet S to the recording start position (step S35). Note that the controller <NUM> may execute a step S35 in parallel with the steps S32-S34. At a timepoint of the controller <NUM> having completed processing up to the step S35, the printer <NUM> is in a state where image recording can be started.

Next, the controller <NUM> executes a predetermined amount of image recording on the sheet S (step S36). Specifically, the controller <NUM> moves the carriage <NUM> in the left-right direction <NUM>. While the carriage <NUM> is moving in the left-right direction <NUM>, the controller <NUM> causes ink corresponding to image data to be discharged from the nozzles <NUM> of the head <NUM>. The step S36 is one example of a recording operation.

Next, the controller <NUM> determines whether there is image data remaining (step S37). In response to having determined there to be image data remaining in the step S37 (step S37: Yes), the controller <NUM> proceeds to a step S38. In this case, the controller <NUM> conveys the sheet S the predetermined amount (step S38), and proceeds to the step S36.

In response to having determined there to be no image data remaining in the step S37 (step S37: No), the controller <NUM> proceeds to a step S39. In this case, the controller <NUM> discharges the sheet S to a predetermined position (step S39). Next, the controller <NUM> moves the carriage <NUM> in a rightward orientation to the standby position (step S40). Next, the controller <NUM> moves the cap <NUM> in an upward orientation from the separated position to the covering position (step S41). After that, the controller <NUM> proceeds to the step S31 in order to execute the next image recording.

At a timepoint of the printer <NUM> having been shipped from a factory, ink does not exist in the ink channels 56b, 56c, <NUM>, 56y, 57b, 57c, <NUM>, 57y. Accordingly, after the printer <NUM> has been set in place and the cartridge holder <NUM> installed with the cartridges 51b, 51c, <NUM>, 51y, the controller <NUM> executes the initial introduction processing depicted in <FIG>. The initial introduction processing is a processing by which the four colors of inks are introduced into the head <NUM> from the cartridges 51b, 51c, <NUM>, 51y. At a timepoint of the controller <NUM> executing a step S51, the carriage <NUM> is located in the standby position, and the cap <NUM> is located in the covering position. The valves 52b, 52c, <NUM>, 52y are closed, and the sub-tanks 53b, 53c, <NUM>, 53y are empty.

After the cartridge holder <NUM> has been installed with the cartridges 51b, 51c, <NUM>, 51y, the controller <NUM> receives an initial introduction instruction from the operating unit (step S51). Specifically, the controller <NUM> waits in the step S51 until it receives the initial introduction instruction. Next, the controller <NUM> stops the ink automatic supply processing (step S52). While executing from a step S53 to a step S60, the controller <NUM> does not execute the ink automatic supply processing depicted in <FIG>. Next, the controller <NUM> initializes to <NUM> a count value N for counting number-of-times-of-suction (step S53).

Next, the controller <NUM> opens the four valves 52b, 52c, <NUM>, 52y (step S54). Thereafter, black ink is supplied from the cartridge 51b to the sub-tank 53b, cyan ink is supplied from the cartridge 51c to the sub-tank 53c, magenta ink is supplied from the cartridge <NUM> to the sub-tank <NUM>, and yellow ink is supplied from the cartridge 51y to the sub-tank 53y. Supply of these inks is performed using water head difference.

Next, the controller <NUM> waits until ink amounts of the four sub-tanks 53b, 53c, <NUM>, 53y all become the threshold values TH1 or more (step S55). Specifically, the controller <NUM> waits in the step S55 until the controller <NUM> respectively receives the sensor signals Sb1, Sc1, Sm1, Sy1 from the sensors 54b, 54c, <NUM>, 54y.

Next, the controller <NUM> closes the four valves 52b, 52c, <NUM>, 52y (step S56). Thereafter, supply of black ink from the cartridge 51b to the sub-tank 53b, supply of cyan ink from the cartridge 51c to the sub-tank 53c, supply of magenta ink from the cartridge <NUM> to the sub-tank <NUM>, and supply of yellow ink from the cartridge 51y to the sub-tank 53y stop.

Next, the controller <NUM> performs suction by driving the pump <NUM> for a predetermined time (step S57). While the controller <NUM> is executing the step S57, the valves 52b, 52c, <NUM>, 52y are in a closed state. The elevator member <NUM> (see <FIG>) is located in the abutting position, and the switching portion <NUM> (see <FIG>) connects the pump <NUM> to the inner space of the exhaust cap <NUM>. Therefore, the ink channels 57b, 57c, <NUM>, 57y are provided with a suction pressure from the head <NUM> side, and the inks that have been stored in the sub-tanks 53b, 53c, <NUM>, 53y are respectively introduced into the ink channels 57b, 57c, <NUM>, 57y.

The pump <NUM> sucks a predetermined amount (a design value or planned suction amount) of ink by being driven for a predetermined time period. The predetermined amount is larger than volumes (capacities) of the sub-tanks 53b, 53c, <NUM>, 53y (each of which may be the difference between a volume in the expanded state and a volume in the contracted state), but smaller than volumes of the ink channels 57b, 57c, <NUM>, 57y. Specifically, the longer a moving distance in the left-right direction <NUM> of the carriage <NUM> is (in other words, the longer the width of the sheet S is), the longer lengths of the ink channels 57b, 57c, <NUM>, 57y will become. Thus, the predetermined amount sucked by the pump <NUM> will become smaller compared to volumes of the ink channels 57b, 57c, <NUM>, 57y more sufficiently. Therefore, the inks of each color that have been introduced into the ink channels 57b, 57c, <NUM>, 57y will not reach the head <NUM> simply by the step S57 having been executed once by the controller <NUM>. Accordingly, the controller <NUM> repeatedly executes the steps S54-S57 a predetermined number-of-times-of-suctions (hereafter, referred to as M), as described below.

Next, the controller <NUM> determines whether the count value N is the predetermined number-of-times-of-suctions M or more (step S58). In response to having determined the count value N is less than the number-of-times-of-suctions M in the step S58 (S58: No), the controller <NUM> proceeds to a step S59. In this case, the controller <NUM> adds <NUM> to the count value N (step S59), and proceeds to the step S54 in order to execute the steps S54-S57 again.

In response to having determined the count value N is the number-of-times-of-suctions M or more in the step S58 step (S58: Yes), the controller <NUM> proceeds to a step S60. In this case, the controller <NUM> opens the four valves 52b, 52c, <NUM>, 52y (step S60). Next, the controller <NUM> resumes ink automatic supply that has been stopped in the step S52 (step S61), and finishes the initial introduction processing.

The number-of-times-of-suctions M in the step S58 is determined such that the following expressions (<NUM>) and (<NUM>) are satisfied, for example. <MAT> <MAT>.

This is provided that, in expressions (<NUM>) and (<NUM>), Q is suction amount required during initial introduction, v is suction amount (total of suction amounts in all of the ink channels) when the pump <NUM> is driven once in the step S57, m is the number of ink channels in the ink supply unit <NUM>, V is volume of any one of the sub-tanks 53b, 53c, <NUM>, 53y, and α and β indicate safety factors. The safety factors α and β take values greater than <NUM>, but less than <NUM>.

When the steps S54-S56 are initially executed by the controller <NUM>, inks of amounts corresponding to the threshold values TH1 respectively flow from the cartridges 51b, 51c, <NUM>, 51y into the sub-tanks 53b, 53c, <NUM>, 53y. Subsequently, when the step S57 is executed for the first time by the controller <NUM>, amounts of inks introduced into the ink channels 57b, 57c, <NUM>, 57y from the sub-tanks 53b, 53c, <NUM>, 53y will differ depending on channel resistances of the ink channels 57b, 57c, <NUM>, 57y, and so on. When the steps S54-S56 are executed a second time and thereafter by the controller <NUM>, inks of amounts corresponding to the amounts of inks that were introduced into the ink channels 57b, 57c, <NUM>, 57y from the sub-tanks 53b, 53c, <NUM>, 53y when the step S57 was executed the previous time by the controller <NUM> will respectively flow from the cartridges 51b, 51c, <NUM>, 51y into the sub-tanks 53b, 53c, <NUM>, 53y.

In the initial introduction processing, after having supplied each of the sub-tanks 53b, 53c, <NUM>, 53y with inks of not less than amounts corresponding to the threshold values TH1, the controller <NUM> drives the pump <NUM> in a state where supply of inks to each of the sub-tanks 53b, 53c, <NUM>, 53y from each of the cartridges <NUM> has been stopped. Hence, if there is a resistance difference between the ink channels 57b, 57c, <NUM>, 57y and there is a difference in suction amounts between the ink channels 57b, 57c, <NUM>, 57y, then, after one or more of the sub-tanks 53b, 53c, <NUM>, 53y connected to one or more of the ink channels 57b, 57c, <NUM>, 57y having a small channel resistance has become empty, the suction pressure of the pump <NUM> will be provided to the other of the ink channels 57b, 57c, <NUM>, 57y. Therefore, a difference in ink amounts flowing into the head <NUM> through the plurality of ink channels 57b, 57c, <NUM>, 57y by suction becomes smaller.

Let it be assumed that in the above-described embodiment, two colors differing from each other are selected from among black, cyan, magenta, and yellow, and the first letters of the English spellings of the selected two colors are set to p and q (p and q are any of b, c, m, and y). The cartridge 51p is one example of a first reservoir, and the cartridge 51q is one example of a second reservoir. The valve 52p is one example of a first valve, and the valve 52q is one example of a second valve. The sub-tank 53p is one example of a first tank, and the sub-tank 53q is one example of a second tank. The sensor 54p is one example of a first sensor, and the sensor 54q is one example of a second sensor. The sensor 55p is one example of a third sensor, and the sensor 55q is one example of a fourth sensor. The threshold value TH1 relating to the sensor 54p is one example of a first threshold value, and the threshold value TH1 relating to the sensor 54q is one example of a second threshold value. The threshold value TH2 relating to the sensor 55p is one example of a third threshold value, and the threshold value TH2 relating to the sensor 55q is one example of a fourth threshold value. The ink channel 56p is one example of a channel connecting the first reservoir and the first tank, and the ink channel 56q is one example of a channel connecting the second reservoir and the second tank. The ink channel 57p is one example of a first channel, and the ink channel 57q is one example of a second channel.

In <FIG>, the controller <NUM> opens the valve 52p in response to receiving the sensor signal Sp2 from the sensor 55p, and closes the valve 52p in response to receiving the sensor signal Sp1 from the sensor 54p subsequently to having received the sensor signal Sp2. This operation is one example of a first valve opening and closing operation. The controller <NUM> opens the valve 52q in response to receiving the sensor signal Sq2 from the sensor 55q, and closes the valve 52q in response to receiving the sensor signal Sq1 from the sensor 54q subsequently to having received the sensor signal Sq2. This operation is one example of a second valve opening and closing operation.

In <FIG>, the initial introduction instruction is one example of a suction instruction, the step S54 is one example of a valve-opening operation, the step S56 is one example of a valve-closing operation, and the step S57 is one example of a suction operation. In response to having received the initial introduction instruction in the step S51, the controller <NUM> executes the valve-opening operation to open the valves 52b, 52c, <NUM>, 52y in the step S54. Subsequently to having executed the valve-opening operation and in response to having received from the sensors 54b, 54c, <NUM>, 54y a sensor signal indicating ink amount of the sub-tanks 53b, 53c, <NUM>, 53y to be the threshold value TH1 or more, the controller <NUM> executes the valve-closing operation to close the valves 52b, 52c, <NUM>, 52y. Subsequently to having executed the valve-closing operation, the controller <NUM> executes the suction operation to drive the pump <NUM> for the predetermined time period.

In the printer <NUM> and ink supply unit <NUM> according to the above-described embodiment, in the case that suction is performed to introduce ink into the plurality of ink channels 56b, 56c, <NUM>, 56y and plurality of ink channels 57b, 57c, <NUM>, 57y connecting the plurality of cartridges <NUM> and the head <NUM>, the pump <NUM> is driven in a state where the ink of not less than a predetermined amount has been supplied to each of the sub-tanks 53b, 53c, <NUM>, 53y and supply of ink to each of the sub-tanks 53b, 53c, <NUM>, 53y from each of the cartridges <NUM> then has been stopped. Therefore, difference in ink amounts flowing into the head <NUM> through the plurality of ink channels 57b, 57c, <NUM>, 57y by suction becomes smaller.

The controller <NUM> executes the valve-opening operation after executing the suction operation. Hence, after the suction operation has been executed, ink will be supplied to each of the sub-tanks 53b, 53c, <NUM>, 53y. The controller <NUM> opens the corresponding one of the valves 52b, 52c, <NUM>, 52y in response to receiving from one of the sensors 55b, 55c, <NUM>, 55y a sensor signal indicating ink amount of one of the sub-tanks 53b, 55c, <NUM>, 55y is less than the threshold value TH2. Hence, when ink amount of each of the sub-tanks 53b, 53c, <NUM>, 53y becomes less than a designated amount, ink will be supplied to each of the sub-tanks 53b, 53c, <NUM>, 53y.

In response to receiving the initial introduction instruction, the controller <NUM> repeatedly executes the valve-opening operation, the valve-closing operation, and the suction operation the predetermined number-of-times-of-suctions M (one example of a predetermined number of times). Hence, a required amount of ink can be introduced into each of the ink channels <NUM>. After having repeatedly executed the valve-opening operation, the valve-closing operation, and the suction operation the number-of-times-of-suctions M, the controller <NUM> executes the valve-opening operation. Hence, after the valve-opening operation, the valve-closing operation, and the suction operation have been repeatedly executed, ink will be supplied to each of the sub-tanks <NUM>.

The controller <NUM> executes the image recording operation in a state of the valves 52b, 52c, <NUM>, 52y having been closed. The controller <NUM> executes the first valve opening and closing operation and the second valve opening and closing operation, and, in response to receiving the initial introduction instruction, does not execute (that is, stops) the first valve opening and closing operation and the second valve opening and closing operation until execution of the suction operation has been completed. Hence, even in the case of automatic supply of inks from each of the cartridges <NUM> to each of the sub-tanks 53b, 53c, <NUM>, 53y being performed, automatic supply of the inks will be stopped and each of the valves 52b, 52c, <NUM>, 52y will be closed until execution of the suction operation is completed.

Various kinds of modified examples may be configured for the printer <NUM> and controller <NUM> according to the above-described embodiment. In the above-described embodiment, controller <NUM> executes the initial introduction processing depicted in <FIG>. In a modified example, a controller <NUM> executes an initial introduction processing depicted in <FIG>.

The initial introduction processing depicted in <FIG> is the initial introduction processing depicted in <FIG> to which a step S71 and a step S74 have been added and in which the step S54 and the step S56 have been respectively replaced by a step S72 and a step S73. The controller <NUM> according to the modified example uses four flags Fb, Fc, Fm, Fy respectively corresponding to black, cyan, magenta, and yellow to execute the initial introduction processing. Each of the flags Fb, Fc, Fm, Fy is cleared in a state where introduced amount of the ink of corresponding color is insufficient, and is set in a state where introduced amounts of the ink of corresponding color is sufficient. The flags Fb, Fc, Fm, Fy are stored in the RAM <NUM> (see <FIG>).

After executing the step S51 and the step S52, the controller <NUM> clears the four flags Fb, Fc, Fm, Fy (step S71). After executing the step S53 or the step S59, the controller <NUM> opens valves corresponding to cleared flags, of the valves 52b, 52c, <NUM>, 52y (step S72). If, for example, the flags Fb, Fy are cleared and the flags Fc, Fm are set, then in the step S72, the controller <NUM> will open the valves 52b, 52y and leave closed the valves 52c, <NUM>.

After executing the step S55, the controller <NUM> closes valves that are open, of the valves 52b, 52c, <NUM>, 52y (step S73). After executing the step S57, the controller <NUM> sets flags of colors whose ink introduction amounts are sufficient, of the flags Fb, Fc, Fm, Fy (step S74). In the step S74, the controller <NUM> determines whether ink introduction amounts of each of the colors are sufficient, based on the sensor signals Sb1, Sc1, Sm1, Sy1, Sb2, Sc2, Sm2, Sy2 respectively outputted from the sensors 54b, 54c, <NUM>, 54y, 55b, 55c, <NUM>, 55y. For example, the controller <NUM> will set the flag Fb in response to a determination that introduction amount of black ink has become sufficient by the step S57 executed immediately priorly.

In the controller <NUM> according to the modified example, after executing the valve-opening operation, the valve-closing operation, and the suction operation a certain number of times which is fewer than the predetermined number-of-times-of-suctions M, the controller <NUM> keeps at least one of the valves 52b, 52c, <NUM>, 52y in a closed state in the valve-opening operation. The above-described certain number of times is one example of a first number of times. Hence, this modified example results in that, for a channel where introduction of ink has been completed, supply of ink from the cartridge <NUM> to the corresponding one of the sub-tanks 53b, 53c, <NUM>, 53y can be stopped and needless discharge of ink thereby prevented.

Claim 1:
A liquid supply device comprising:
a first reservoir (51b) configured to store a first liquid;
a second reservoir (51c) configured to store a second liquid;
a first tank (53b) positioned lower than the first reservoir, wherein an outer shape of the first tank can change between an expanded state and a contracted state depending on an amount of the first liquid stored therein;
a second tank (53c) positioned lower than the second reservoir, wherein an outer shape of the second tank can change between an expanded state and a contracted state depending on an amount of the second liquid stored therein;
a first valve (52b) configured to open and close a first channel (56b) connecting the first reservoir and the first tank;
a second valve (52c) configured to open and close a second channel (56c) connecting the second reservoir and the second tank;
a head (<NUM>), wherein the liquid supply device is configured such that the first liquid is capable of flowing into the head from the first tank through a third channel (57b), and the second liquid is capable of flowing into the head from the second tank through a fourth channel (57c);
a suction mechanism (<NUM>) configured to apply a suction pressure to the third channel and the fourth channel from a head side of the third channel and the fourth channel, wherein the head side is the side at which the head is positioned;
a first sensor (54b);
a second sensor (54c); and
a controller (<NUM>), wherein
the controller is configured to:
execute a valve-opening operation of opening the first valve and the second valve, in response to receiving of a suction instruction;
execute, after executing the valve-opening operation, a valve-closing operation of closing the first valve in response to receiving of a first signal from the first sensor, and closing the second valve in response to receiving of a second signal from the second sensor, the first signal being a signal indicating that an amount of the first liquid in the first tank is a first threshold value or more, the second signal being a signal indicating that an amount of the second liquid in the second tank is a second threshold value or more; and
execute, after executing the valve-closing operation, a suction operation of driving the suction mechanism for a predetermined time period.