Patent Description:
As an apparatus which discharges an ink stored in a tank from a nozzle so as to perform recording of an image, an ink-jet pen is known (see Patent Literature <NUM>). In this ink-jet pen, a liquid surface of the ink stored in an ink cartridge is positioned above an opening of the nozzle. In the ink cartridge, a gas layer is not communicated with outside, or a valve is provided on a gas channel which communicates the gas layer to the outside.

[Patent Literature <NUM>] Japanese Patent Application Laid-Open No. <CIT>.

In a case that the gas layer of the ink cartridge is not communicated with the outside and that the ink is consumed, the pressure of the gas layer is lowered. As a result, there is a fear that a meniscus formed in the opening of the nozzle might be broken or destroyed. Further, in a case that the valve, etc., is provided so as to maintain the pressure of the gas layer of the ink cartridge to be constant while communicating the gas layer with the outside, the structure of the ink-jet head might become complex, or the size of the ink-jet head might become great. On the other hand, in a case that the gas layer of the ink cartridge is always communicated with the outside, there is such a fear that the meniscus formed in the opening of the nozzle might be destroyed due to the head difference (waterhead difference).

The present invention has been made in view of the above-described situation, and an object of the present invention is to provide means for maintaining the meniscus formed in the opening of the nozzle in a state that a reservoir in which a liquid is stored is communicated with the outside of the reservoir by an atmosphere port.

According to the present invention, the meniscus formed in the opening of the nozzle is maintained in a state that the reservoir in which the liquid is stored is communicated with the outside of the reservoir by the atmosphere port.

In the following, an embodiment of the present invention will be explained. Note that the embodiment which is to be explained below is merely an example of the present invention; it is needless to say that the embodiment can be appropriately changed without departing from the scope of the appended claims. Further, in the following explanation, advancement or movement (progress) directed from a starting point to an end point of an arrow is expressed as an "orientation", and going forth and back on a line connecting the starting point and the end point of the arrow is expressed as a "direction". Furthermore, in the following description, an up-down direction <NUM> is defined, with a state in which a multifunction peripheral <NUM> is operably installed (the state of <FIG>) as the reference; a front-rear direction <NUM> is defined, with a side on which an opening <NUM> is provided being defined as a front surface <NUM>; and a left-right direction <NUM> is defined, with the multifunction peripheral <NUM> as seen from the front side. The up-down direction <NUM>, the front-rear direction <NUM>, and the left-right direction <NUM> are orthogonal to one another.

As depicted in <FIG>, the multifunction peripheral <NUM> (an example of a "liquid discharging apparatus") has a casing (housing) <NUM> which has a substantially rectangular parallelepiped shape. A printer part <NUM> is provided at a lower part of the casing <NUM>. The multifunction peripheral <NUM> has a various kinds of functions such as a facsimile function, a print function, etc. The multifunction peripheral <NUM> has a function, as the print function, of recording an image on one surface of a sheet <NUM> (paper sheet <NUM>; see <FIG>) in an ink-jet system. Note that the multifunction peripheral <NUM> may also be configured to record an image on both surfaces of the sheet <NUM>. An operating part <NUM> is provided on an upper part of the casing <NUM>. The operating part <NUM> is constructed of a button configured to be operated for instructing the image recording, for performing a various kinds of settings, etc., a liquid crystal display configured to display a various kinds of information thereon, and the like. In the embodiment, the operating part <NUM> is constructed of a touch panel having both of the function of the button and the function of the liquid crystal display.

As depicted in <FIG>, the printer part <NUM> has a feed tray <NUM>, a feeding part <NUM>, an outer guide member <NUM>, an inner guide member <NUM>, a conveying roller pair <NUM>, a discharging roller pair <NUM>, a platen <NUM>, a recording part <NUM>, an encoder <NUM> (see <FIG>), a rotary encoder <NUM> (see <FIG>), a controller <NUM> (see <FIG>) and a memory <NUM> (see <FIG>) which are arranged inside the casing <NUM>. In the inside of the casing <NUM>, a various kinds of state sensors (not depicted in the drawings), which are configured to detect the state of the multifunction peripheral <NUM> and to output a signal in accordance with a result of detection, are arranged.

As depicted in <FIG>, an opening <NUM> is formed in the front surface <NUM> of the printer part <NUM>. The feed tray <NUM> is insertable and removable with respect to the casing <NUM> via the opening <NUM>, by moving in the front-rear direction <NUM>. The feed tray <NUM> is movable between a feeding position (a position depicted in <FIG> and <FIG>) at which the feed tray <NUM> is installed in the casing <NUM>, and a non-feeding position at which the feed tray <NUM> is removed (detached) from the casing <NUM>. The feed tray <NUM> is inserted rearward with respect to the casing <NUM> to be moved to the feeding position, and the feed tray <NUM> is pulled frontward with respect to the casing <NUM> to be moved to the non-feeding position.

The feed tray <NUM> is a member having a box-like shape of which upper part is opened, and is configured to store a sheet <NUM>. As depicted in <FIG>, a plurality of pieces of the sheet <NUM> are supported by a bottom plate <NUM> of the feed tray <NUM> in a state that the sheets <NUM> are overlaid on each other. The discharge tray <NUM> is arranged at a location which is above a front part of the feed tray <NUM>. A sheet <NUM> on which image recording has been performed by the recording part <NUM> and which is discharged is supported by an upper surface of the discharge tray <NUM>. In a case that the feed tray <NUM> is at the feeding position, the sheet <NUM> supported by the feed tray <NUM> is allowed to be fed to a conveying route <NUM>.

As depicted in <FIG>, the feeding part <NUM> is arranged at a location below the recording part <NUM> and above the bottom plate <NUM> of the feed tray <NUM>. The feeding part <NUM> is provided with a feeding roller <NUM>, a feeding arm <NUM>, a driving transmitting mechanism <NUM> and a shaft <NUM>. The feeding roller <NUM> is supported rotatably at a forward end part of the feeding arm <NUM>. The feeding arm <NUM> rotates in a direction of an arrow <NUM>, with the shaft <NUM> provided on a base part of the feeding arm <NUM> as the center of rotation. With this, the feeding roller <NUM> is capable of making contact with and separating away from the feed tray <NUM> or the sheet <NUM> which is supported by the feed tray <NUM>.

The feeding roller <NUM> rotates by a driving force, of a feeding motor <NUM> (see <FIG>), which is transmitted to the feeding roller <NUM> by the driving transmitting mechanism <NUM> constructed of a plurality of gears meshed with each other. With this, among the sheets <NUM> supported by the bottom plate <NUM> of the feed tray <NUM> at the feeding position, an uppermost sheet <NUM> which makes contact with the feeding roller <NUM> is fed to the conveying route <NUM>. Note that the driving transmitting mechanism <NUM> is not limited to or restricted by the aspect in which the plurality of gears are meshed with each other; for example, the driving transmitting mechanism <NUM> may be a belt which is stretched or spanned between the shaft <NUM> and the shaft of the feeding roller <NUM>.

As depicted in <FIG>, the conveying route <NUM> is extended from a rear end part of the feed tray <NUM>. The conveying route <NUM> includes a curved part <NUM> and a straight part <NUM>. The curved part <NUM> extends toward the upper side while making a U-turn from the rear side to the front side. The straight part <NUM> extends substantially along the front-rear direction <NUM>.

The curved part <NUM> is formed by the outer guide member <NUM> and the inner guide member <NUM> which face or are opposite to each other, with a predetermined spacing distance therebetween. The outer guide member <NUM> and the inner guide member <NUM> are provided to extend in the left-right direction <NUM>. At a position wherein the recording part <NUM> is arranged, the straight part <NUM> is formed by the recording part <NUM> and the platen <NUM> which face each other with a predetermined spacing distance therebetween.

The sheet <NUM> supported by the feed tray <NUM> is conveyed in the curved part <NUM> by the feeding roller <NUM>, and reaches the conveying roller pair <NUM>. The sheet <NUM> pinched or held by the conveying roller pair <NUM> is conveyed frontward in the straight part <NUM> toward the recording part <NUM>. The recording part <NUM> records an image on the sheet <NUM> which has reached a location immediately below the recording part <NUM>. The sheet <NUM> having the image recorded thereon is conveyed frontward in the straight part <NUM>, and is discharged to the discharge tray <NUM>. As described above, the sheet <NUM> is conveyed along a conveying orientation <NUM> which is indicated by an arrow of an alternate long and short dash line in <FIG>.

As depicted in <FIG>, the conveying roller pair <NUM> is arranged in the straight part <NUM>. The discharging roller pair <NUM> is arranged, in the straight part <NUM>, on the downstream side in the conveying orientation <NUM> with respect to the conveying roller pair <NUM>.

The conveying roller pair <NUM> includes a conveying roller <NUM> and a pinch roller <NUM> which is arranged at a location below the conveying roller <NUM> so as to face the conveying roller <NUM>. The pinch roller <NUM> is pressed toward the conveying roller <NUM> by an elastic member (not depicted in the drawings) such as a coil spring, etc. The conveying roller pair <NUM> is capable of pinching or holding the sheet <NUM> therebetween.

The discharging roller pair <NUM> includes a discharging roller <NUM> and a spur roller <NUM> which is arranged at a location above the discharging roller <NUM> so as to face the discharging roller <NUM>. The spur roller <NUM> is pressed toward the discharging roller <NUM> by an elastic member (not depicted in the drawings) such as a coil spring, etc. The discharging roller pair <NUM> is capable of pinching or holding the sheet <NUM> therebetween.

The conveying roller <NUM> and the discharging roller <NUM> rotate in a case that a driving force is applied to the conveying roller <NUM> and the discharging roller <NUM> from the conveying motor <NUM> (see <FIG>). In a case that the conveying roller <NUM> rotates in a state that the sheet <NUM> is pinched by the conveying roller pair <NUM>, the sheet <NUM> is conveyed in the conveying orientation <NUM> by the conveying roller pair <NUM>, and is conveyed onto the platen <NUM>. In a case that the discharging roller <NUM> rotates in a state that the sheet <NUM> is pinched by the discharging roller pair <NUM>, the sheet <NUM> is conveyed in the conveying orientation <NUM> by the discharging roller pair <NUM>, and is discharged onto the discharge tray <NUM>. Note that a common motor may be used as the conveying motor <NUM> and the feeding motor <NUM>. In such a case, there is provided a configuration wherein a driving transmitting route from the common motor to each of the rollers is switchable.

Note that a mechanism or member configured to convey the sheet <NUM> is not limited to the roller pairs as described above. For example, it is allowable that a conveying belt is arranged, instead of the conveying roller pair <NUM> and the discharging roller pair <NUM>.

As depicted in <FIG>, the platen <NUM> is arranged in the straight part <NUM> of the conveying route <NUM>. The platen <NUM> faces the recording part <NUM> in the up-down direction <NUM>. The platen <NUM> supports the sheet <NUM> which is being conveyed in the conveying route <NUM> from therebelow. The sheet <NUM> which is being conveyed in the conveying route <NUM> passes an area between a right end and a left end of the platen <NUM> in the left-right direction <NUM> (hereinafter referred to as a "medium passing area").

As depicted in <FIG>, the recording part <NUM> is arranged at a location above the platen <NUM> so as to face the platen <NUM>. The recording part <NUM> is provided with a carriage <NUM>, a head <NUM> and a reservoir (storing part, storage) <NUM>.

The carriage <NUM> is supported to be movable in the left-right direction <NUM> (an example of a "scanning direction") which is orthogonal to the conveying orientation <NUM>, by two guide rails <NUM> and <NUM> which are arranged in the front-rear direction <NUM> with a spacing distance therebetween. The carriage <NUM> is movable, in the left-right direction <NUM>, between a position on the right side with respect to the medium passing area and a position on the left side with respect to the medium passing area. Note that the moving direction of the carriage <NUM> is not limited to the left-right direction <NUM>, and the moving direction may be a direction crossing the conveying orientation <NUM>.

The guide rail <NUM> is arranged on the upstream side in the conveying orientation <NUM> with respect to the head <NUM>. The guide rail <NUM> is arranged on the downstream side in the conveying orientation <NUM> with respect to the head <NUM>. The guide rails <NUM> and <NUM> are supported by a pair of side frames (not depicted in the drawings) which are arranged, in the left-right direction <NUM>, at the outside of the straight part <NUM> of the conveying route <NUM>. The carriage <NUM> is moved in a case that a driving force is applied to the carriage <NUM> from a carriage driving motor <NUM> (see <FIG>).

The encoder <NUM> (see <FIG>) is arranged in the guide rail <NUM> or the guide rail <NUM>. The encoder <NUM> includes an encoder strip extending in the left-right direction <NUM>, and an optical sensor which is provided, on the carriage <NUM>, at a location facing the encoder strip. A pattern, in which light transmitting parts each configured to allow a light to transmit therethrough and light shielding parts each configured to shield the light are alternately arranged at an equal pitch in the left-right direction <NUM>, is formed in the encoder strip. The optical sensor detects the light transmitting parts and the light shielding parts, thereby detecting a pulse signal. The pulse signal is a signal in accordance with the position in the left-right direction <NUM> of the carriage <NUM>. The pulse signal is outputted to the controller <NUM> (see <FIG>).

The head <NUM> is supported by the carriage <NUM>. A lower surface <NUM> of the head <NUM> is exposed downward, and faces the platen <NUM>. The head <NUM> is provided with a plurality of nozzles <NUM>, an ink channel <NUM> and a piezoelectric element <NUM> (see <FIG>).

The plurality of nozzles <NUM> are opened in the lower surface <NUM> of the head <NUM>. The ink channel <NUM> connects or links the reservoir <NUM> and the plurality of nozzles <NUM>. The piezoelectric element <NUM> (see <FIG>) deforms a part of the ink channel <NUM> to thereby cause a droplet of an ink (ink droplet) to be discharged or ejected downward from the nozzles <NUM>. The piezoelectric element <NUM> is driven or activated by an electric supply from the controller <NUM> (see <FIG>). In such a manner, the head <NUM> has the plurality of nozzles <NUM> which discharges or ejects an ink (an example of a "liquid").

The reservoir <NUM> is supported by the carriage <NUM> in a state that the reservoir <NUM> is installed in the carriage <NUM>. The reservoir <NUM> has an internal space <NUM>. An ink <NUM> is stored in the internal space <NUM>. In the present embodiment, the recording part <NUM> includes one reservoir <NUM>. An ink <NUM> of the black color (black ink) is stored in this one reservoir <NUM>. Note that the color of the ink <NUM> stored in the reservoir <NUM> is not limited to the black color.

The reservoir <NUM> is positioned above the head <NUM>. Note that, although the entirety of the reservoir <NUM> is located above the head <NUM> in the present embodiment, it is also allowable that a part of the reservoir <NUM> is located above the head <NUM>, and another part, of the reservoir <NUM>, which is different from the part is located at a height equal to or lower than the height of the head <NUM>. The internal space <NUM> of the reservoir <NUM> is communicated with the plurality of nozzle <NUM> via the ink channel <NUM>. With this, the ink <NUM> is suppled from the internal space <NUM> to the plurality of nozzles <NUM>.

An inlet port <NUM> via which the ink <NUM> is poured or supplied to the internal space <NUM> is provided in an upper wall <NUM> of the reservoir <NUM>. The inlet port <NUM> penetrates the upper wall <NUM> in a thickness direction of the upper wall <NUM> so as to communicate (connect) the internal space <NUM> with the outside of the reservoir <NUM>. A projected wall <NUM> (see <FIG>) is provided in a surrounding of the inlet port <NUM> in the upper surface of the upper wall <NUM>. A lid <NUM> is fitted to the projected wall <NUM>, thereby closing the inlet port <NUM>. In a case that the lid <NUM> is removed or detached from the projected wall <NUM>, the inlet port <NUM> is exposed to the outside. In this state, a bottle (not depicted in the drawings) is inserted into the inlet port <NUM>, and the ink <NUM> is poured from the bottle into the internal space <NUM> via the inlet port <NUM>. Note that the inlet port <NUM> may be provided at another position which is different from the upper wall <NUM>, provided that at the another position, an upper part of the internal space <NUM> is allowed to communicate with the outside.

As depicted in <FIG>, an atmosphere opening port (atmosphere port) <NUM> is provided on the upper wall <NUM> of the reservoir <NUM>. In the internal space <NUM> of the reservoir <NUM>, air enters into a part, of the internal space <NUM>, in which the ink <NUM> is not present. The part, of the internal space <NUM>, into which the air has been entered is referred to as a gas layer. The atmosphere opening port <NUM> communicates (connects) the gas layer of the reservoir <NUM> with the outside of the reservoir <NUM>.

The rotary encoder <NUM> depicted in <FIG> is constructed of an encoder disk which is provided on a shaft of the conveying motor <NUM> (see <FIG>) and which is configured to rotate together with the conveying motor <NUM>, and an optical sensor. A pattern, in which transmitting parts each configured to allow a light to transmit therethrough and non-transmitting parts each configured not to allow the light transmit therethrough are alternately arranged at an equal pitch in a circumferential direction of the encoder disk, is formed in the encoder disk. In a case that the encoder disk rotates, a pulse signal is generated each time the transmitting part and the non-transmitting part are detected by the optical sensor. The generated pulse signal is outputted to the controller <NUM> (see <FIG>). The controller <NUM> calculates a rotating amount of the conveying motor <NUM> based on the pulse signal. Note that the rotary encoder <NUM> may be provided on a location which is different from the conveying motor <NUM>, for example, on the feeding motor <NUM>, the conveying roller <NUM>, etc..

In the following, the configurations of the controller <NUM> and the memory <NUM> will be explained, with reference to <FIG>. The controller <NUM> is configured to control the entire operation of the multifunction peripheral <NUM>. The controller <NUM> is provided with a CPU <NUM> and an ASIC <NUM>. The memory <NUM> is provided with a ROM <NUM>, a RAM <NUM> and an EEPROM <NUM>. The CPU <NUM>, the ASIC <NUM>, the ROM <NUM>, the RAM <NUM> and the EEPROM <NUM> are connected to one another by an internal bus <NUM>.

The ROM <NUM> stores therein a program for causing the CPU <NUM> to control a various kinds of operations, etc. The RAM <NUM> is used as a storage area temporarily storing data and/or a signal to be used in a case that the CPU <NUM> executes the program, or as a working area for data processing. The EEPROM <NUM> stores a setting and/or a flag, etc., to be held or stored even after the power source is switched off.

The conveying motor <NUM>, the feeding motor <NUM> and the carriage driving motor <NUM> are connected to the ASIC <NUM>. Driving circuit each of which controls one of the respective motors are installed in the ASIC <NUM>. The CPU <NUM> outputs driving signals each of which is for rotating one of the respective motors to one of the driving circuits corresponding to one of the respective motors. Each of the driving circuits outputs a driving current, in accordance with the driving signal obtained from the CPU <NUM>, to one of the motors corresponding thereto. With this, the corresponding motor is rotated. Namely, the controller <NUM> controls the feeding motor <NUM> to cause the feeding part <NUM> to feed the sheet <NUM>. Further, the controller <NUM> controls the conveying motor <NUM> to cause the conveying roller pair <NUM> and the discharging roller pair <NUM> to convey the sheet <NUM>. Furthermore, the controller <NUM> controls the carriage driving motor <NUM> to move the carriage <NUM>.

Moreover, the optical sensor of the rotary encoder <NUM> is connected to the ASIC <NUM>. The controller <NUM> calculates the rotating amount of the conveying motor <NUM> based on the electric signal received from the optical sensor of the rotary encoder <NUM>. Further, the encoder <NUM> is connected to the ASIC <NUM>. The controller <NUM> recognizes the position of the carriage <NUM> and/or the presence or absence of the movement of the carriage <NUM>, based on the pulse signal received from the encoder <NUM>.

Further, the piezoelectric element <NUM> is connected to the ASIC <NUM>. The piezoelectric element <NUM> is driven or activated by the electric supply from the controller <NUM> via a non-illustrated drive circuit. The controller <NUM> controls the electric supply to the piezoelectric element <NUM> so as to selectively discharge or eject an ink droplet from the plurality of nozzles <NUM>. Furthermore, a state sensor (not depicted in the drawings) is connected to the ASIC <NUM>. The controller <NUM> performs an image recording processing, an abnormality processing, etc., which will be described later on, based on a signal received from the state sensor.

In a case that the controller <NUM> performs recording of an image on the sheet <NUM>, the controller <NUM> alternately executes a conveying processing and a printing processing. The conveying processing is a processing of causing the conveying roller pair <NUM> and the discharging roller pair <NUM> to convey the sheet <NUM> only by a predetermined line feed amount. The controller <NUM> controls the conveying motor <NUM> to thereby cause the conveying roller pair <NUM> and the discharging roller pair <NUM> to execute the conveying processing. The printing processing is a processing of controlling the electric supply to the piezoelectric element <NUM> while moving the carriage <NUM> along the left-right direction <NUM> to thereby cause the head <NUM> to discharge the ink droplet from the nozzle <NUM>. During the printing processing, the carriage <NUM> is positioned in the medium passing area (an area between the right end and the left end of the platen <NUM>), and faces or is opposite to the platen <NUM>.

During a period of time (time interval) between the conveying processing which is currently being executed (current conveying processing) and the conveying processing which is to be executed next (a next conveying processing), the controller <NUM> stops the sheet <NUM> for a predetermined period of time. Further, the controller <NUM> executes the printing processing during the period of time for which the sheet <NUM> is stopped. Namely, in the printing processing, the controller <NUM> executes one pass for causing the ink droplets to be discharged from the nozzles <NUM> while causing the carriage <NUM> to move leftward or rightward. With this, an image recording for the one pass is executed with respect to the sheet <NUM>.

The controller <NUM> is capable of recording an image on an entire area, of the sheet <NUM>, in which an image is recordable, by alternately and repeatedly executing the conveying processing and the printing processing. Namely, the controller <NUM> records an image on one piece of the sheet <NUM> with a plurality of passes (a pass performed for a plurality of times). In such a manner, in the multifunction peripheral <NUM>, the carriage <NUM> moves with the head <NUM> and the reservoir <NUM> mounted thereon. The carriage <NUM> moves in the left-right direction <NUM>, and the head <NUM> discharges the ink(s) while the carriage <NUM> is moving in the left-right direction <NUM>.

Note that the controller <NUM> is not limited to or restricted by the controller <NUM> as described above. The controller <NUM> may be configured such that only the CPU <NUM> performs the various kinds of processing or that only the ASIC <NUM> performs the various kinds of processing, or that the CPU <NUM> and the ASIC <NUM> perform the various kinds of processing in a cooperative manner. Alternatively, the controller <NUM> may be configured such that one CPU <NUM> singly performs the processing, or that a plurality of pieces of the CPU <NUM> perform the processing in a sharing manner. Still alternatively, the controller <NUM> may be configured such that one ASIC <NUM> singly performs the processing, or that a plurality of pieces of the ASIC <NUM> perform the processing in a sharing manner.

In the printer part <NUM> configured as described above, a series of image recording controls by which the sheet <NUM> is conveyed and an image is recorded on the conveyed sheet <NUM> is executed by the controller <NUM>. In the following, the image recording control by the controller <NUM> will be explained, with reference to a flowchart depicted in <FIG>.

In a case that the image recording control is not executed, the carriage <NUM> is located at the outside of the medium passing area in the left-right direction <NUM> (this position is referred to as a "maintenance position"), and the carriage <NUM> does not face the platen <NUM>.

A print command is transmitted, to the controller <NUM>, from the operating part <NUM> (see <FIG>) of the multifunction peripheral <NUM> and/or an external apparatus or device connected to the multifunction peripheral <NUM>. The print command includes a command of starting the image recording control, information regarding the size of the sheet <NUM>, and print data of image recording to be performed on the sheet <NUM>.

In a case that the controller <NUM> obtains the print command (step S10: YES), the controller <NUM> executes feeding of a sheet <NUM> supported by the feed tray <NUM> (step S20).

In step S20, the controller <NUM> drives the feeding motor <NUM>. With this, the feeding roller <NUM> feeds the sheet <NUM> supported by the feed tray <NUM> to the conveying route <NUM>. Further, the controller <NUM> drives the conveying motor <NUM>. With this, in a case that a forward end of the sheet <NUM> fed to the conveying route <NUM> by the feeding roller <NUM> reaches the conveying roller pair <NUM>, the conveying roller pair <NUM> conveys the sheet <NUM> in the conveying orientation <NUM>.

Next, the controller <NUM> drives the carriage driving motor <NUM> to thereby move the carriage <NUM> from the maintenance position to a start position. The start position is a moving start position of the carriage <NUM> in a case that the printing processing (step S30) is executed, and is determined based on the print data. In step S20, a feeding operation of the sheet <NUM> and a moving operation of the carriage <NUM> are executed in parallel.

Next, the controller <NUM> executes the printing processing (step S30). In the printing processing in step S30, the controller <NUM> executes one pass. Namely, the controller <NUM> causes the ink droplets to be discharged from the nozzles <NUM>, while moving the carriage <NUM> to move from the start position. Note that, it is allowable that the carriage <NUM> which has started moving from the maintenance position in step S20 does not stop at the start position, and keeps moving for the print processing. Of course, it is allowable that the carriage <NUM> temporarily stops at the start position.

Next, the controller <NUM> determines whether or not the image recording on a current sheet <NUM> is ended, based on the information regarding the size of the sheet <NUM> and/or the print data included in the print command (step S40).

In a case that, in step S40, the image recording on the current sheet <NUM> is not ended (step S40: NO), the conveying processing is executed (step S50). In the conveying processing in step S50, the controller <NUM> drives the conveying motor <NUM> to thereby cause the conveying roller pair <NUM> and the discharging roller pair <NUM> to convey the sheet <NUM> by a predetermined line feed amount. Afterwards, the control by the controller <NUM> proceeds to step S30.

In step S40, in a case that the image recording on the current sheet <NUM> is ended (step S40: YES), the controller <NUM> causes the conveying roller pair <NUM> and the discharging roller pair <NUM> to convey the sheet <NUM> in the conveying orientation <NUM> to thereby discharge the sheet <NUM> to the discharge tray <NUM> (step S60).

Next, the controller <NUM> determines whether or not there still is image data which is included in the print command and which has not been recorded on the sheet <NUM>, namely, whether or not there is image recording to be performed on a next page (step S70).

In a case that there is image recording to be performed on the next page (step S70: YES), the control by the controller <NUM> proceeds to step S20. In this case, the controller <NUM> feeds a succeeding sheet <NUM> from the feed tray <NUM> to the conveying route <NUM> (step S20). Note that the feeding of the succeeding sheet <NUM> (step S20) may be executed in parallel with the discharging of the preceding sheet <NUM> (step S60). In a case that there is not any image recording to be performed on the next page (step S70: NO), the controller <NUM> ends the series of image recording controls.

Note that although a case that the controller <NUM> performs the image recording normally has been explained here, it is also allowable that the controller <NUM> executes a processing of detecting an abnormality and a processing to be executed in a case that an abnormality has been detected (each of these processing is not depicted in the drawings), while performing the image recording.

In the following, regarding a case that the multifunction peripheral <NUM> performs the image recording, a condition for maintaining the meniscus of the nozzle <NUM> of the head <NUM> will be explained. In <FIG>, the reservoir <NUM> and the nozzle <NUM> are schematically depicted. Although one piece of the nozzle <NUM> is depicted in <FIG> in order that the drawings are easily understood, the plurality of nozzles <NUM> are actually present.

As depicted in <FIG>, the ink <NUM> is stored in the reservoir <NUM> while forming a liquid surface LS. In <FIG>, the liquid surface LS when the ink <NUM> of a maximum storable amount (that is, a maximum amount of the ink <NUM> storable in the reservoir <NUM>) is stored in the reservoir <NUM> is depicted by dotted line with the reference sign of LSmax. In the present embodiment, the maximum storable amount corresponds to an amount when the ink <NUM> fills the internal space <NUM> and the liquid surface LS of the ink <NUM> is coplanar with the upper end of the atmosphere opening port <NUM> (or upper surface 80u of the reservoir <NUM>). In a case that the ink <NUM> of the maxim storable amount is stored in the reservoir <NUM>, the height of the liquid surface LS is located above the opening of the nozzle <NUM> (that is, located at a position higher than the position of the opening of the nozzle <NUM>). The atmosphere opening port <NUM> communicates (connects) the gas layer of the reservoir <NUM> (a part, in the internal space <NUM>, in which the ink <NUM> is not present) and the outside.

As depicted in <FIG>, a meniscus having a downwardly projected or convex shape is formed by the ink <NUM> in the opening of the nozzle <NUM>. A gravity F1 acting downward and a surface tension F2 acting upward due to a contact between the ink <NUM> and the inner surface of the nozzle <NUM> act on the ink <NUM> in the vicinity of the opening of the nozzle <NUM>. In a case that the surface tension F2 is not less than the gravity F1, the meniscus formed in the opening of the nozzle <NUM> is maintained.

It is provided that: an inner diameter of the nozzle <NUM> is (d), a head difference (waterhead difference) which is a difference in height between the meniscus (that is, the position of the base portion of the meniscus, or the position of the opening of the nozzle <NUM>) formed in the opening of the nozzle <NUM> and the liquid surface LS in the maxim amount (maximum storable amount) of the ink <NUM> storable in the reservoir <NUM> is (h), a specific weight (specific gravity) of the ink <NUM> is (ρ), a surface tension of the ink <NUM> is (σ), a contact angle defined between the ink <NUM> and the inner surface of the nozzle <NUM> is (θ), and gravitational acceleration is (g). The gravity F1 acting downward on the ink in the vicinity of the opening of the nozzle <NUM> is given by: πd<NUM> / <NUM> × ρgh. The surface tension F2 acting upward on the ink in the vicinity of the opening of the nozzle <NUM> is given by: πdσcosθ. In a case that these formulae are substituted for and arranged in a relational expression: F1 ≤ F2, the following expression (<NUM>) is obtained: <MAT>.

In the multifunction peripheral <NUM>, in a case that the specific weight (ρ) of the ink <NUM>, the surface tension (σ) of the ink <NUM>, the contact angle (θ) defined between the ink <NUM> and the inner surface of the nozzle <NUM> are provided, the inner diameter (d) of the nozzle <NUM> and the head difference (h) are determined so as to satisfy the expression (<NUM>). In a case that the inner diameter (d) is made to be the horizontal axis and that the head difference (h) is made to be the vertical axis, a range satisfying the expression (<NUM>) is a left lower side (hatched part) of a curved line indicated in <FIG>. In a case that the combination of the value of the inner diameter (d) and the value of the head difference (h) is in the inside of the hatched part indicated in <FIG>, the meniscus formed in the opening of the nozzle <NUM> is maintained.

In the following, a specific example of the range in which the inner diameter (d) of the nozzle <NUM> and the head difference (h) satisfy the expression (<NUM>) will be explained. The viscosity of the ink used in a printer of the ink-jet system, such as the multifunction peripheral <NUM>, etc., is, for example, not less than <NUM> cps and less than <NUM> cps. As the ink, for example, a water-based ink which contains not less than <NUM>% and not more than <NUM>% of water is used. The specific weight (ρ) of the ink is, for example, not less than <NUM>/cm<NUM> and not more than <NUM>/cm<NUM>. The surface tension σ of the ink is, for example, not less than <NUM> mN/m and not more than <NUM> mN/m. The contact angle (θ) defined between the inner surface of the nozzle and the ink is, for example, not less than <NUM>° and not more than <NUM>°.

The surface tension (σ) of the ink is obtained, for example, by using the Wilhelmy method. The contact angle (θ) defined between the inner surface of the nozzle and the ink is obtained by measuring a contact angle defined in a case of dripping the ink onto a plate formed of a same material as that of the nozzle by, for example, using the θ/<NUM> method (half-angle method).

In the following, a set of conditions of "the specific weight (ρ) of the ink is <NUM>/cm<NUM>", "the surface tension (σ) of the ink is <NUM> mN/m" and "the contact angle (θ) defined between the inner surface of the nozzle and the ink is <NUM>°" is referred to as a "first condition", and a set of conditions of "the specific weight (ρ) of the ink is <NUM>/cm<NUM>", "the surface tension (σ) of the ink is <NUM> mN/m" and "the contact angle (θ) defined between the inner surface of the nozzle and the ink is <NUM>°" is referred to as a "second condition".

In a case that the first condition is satisfied in the multifunction peripheral <NUM>, the range satisfying the expression (<NUM>) is a left lower side of a curved line indicated in <FIG>. As indicated in <FIG>, eight areas <NUM> to <NUM> are set on the left lower side of the curved line. As indicated in <FIG>, four areas <NUM> to <NUM> are set on the left lower side of the curved line. In a case that the combination of the value of the inner diameter (d) and the value of the head difference (h) is within any one of the areas <NUM> to <NUM> and the areas <NUM> to <NUM>, the expression (<NUM>) is satisfied and the meniscus formed in the opening of the nozzle <NUM> is maintained.

The area <NUM> indicated in <FIG> is an area in which the inner diameter (d) is not less than <NUM> and less than <NUM>, and the head difference (h) is not more than <NUM>. In a case that the inner diameter (d) is not less than <NUM> and less than <NUM>, by making the head difference (h) to be not more than <NUM>, the expression (<NUM>) is satisfied and the meniscus formed in the opening of the nozzle <NUM> is maintained.

The area <NUM> is an area in which the inner diameter (d) is not less than <NUM> and less than <NUM>, and the head difference (h) is not more than <NUM>. In a case that the inner diameter (d) is not less than <NUM> and less than <NUM>, by making the head difference (h) to be not more than <NUM>, the expression (<NUM>) is satisfied and the meniscus formed in the opening of the nozzle <NUM> is maintained.

The area <NUM> depicted in <FIG> is an area in which the inner diameter (d) is not less than <NUM> and less than <NUM>, and the head difference (h) is not more than <NUM>. In a case that the head difference (h) is not more than <NUM>, by making the inner diameter (d) to be not less than <NUM> and less than <NUM>, the expression (<NUM>) is satisfied and the meniscus formed in the opening of the nozzle <NUM> is maintained.

The area <NUM> is an area in which the inner diameter (d) is not less than <NUM> and less than <NUM>, and the head difference (h) is greater than <NUM> and not more than <NUM>. In a case that the head difference (h) is greater than <NUM> and not more than <NUM>, by making the inner diameter (d) to be not less than <NUM> and less than <NUM>, the expression (<NUM>) is satisfied and the meniscus formed in the opening of the nozzle <NUM> is maintained.

The area <NUM> is an area in which the inner diameter (d) is not less than <NUM> and less than <NUM>, and the head difference (h) is greater than <NUM> and not more than <NUM>. In a case that the head difference (h) is greater than <NUM> and not more than <NUM>, by making the inner diameter (d) to be not less than <NUM> and less than <NUM>, the expression (<NUM>) is satisfied and the meniscus formed in the opening of the nozzle <NUM> is maintained. Note that the reason by which the inner diameter (d) of the nozzle <NUM> is made to be not less than <NUM> is that if the inner diameter (d) is smaller than <NUM>, clogging of the ink may occur frequently.

In a case that the second condition is satisfied in the multifunction peripheral <NUM>, a condition for maintaining the meniscus formed in the opening of the nozzle <NUM> is as follows. That is: in a case that the inner diameter (d) is not less than <NUM> and less than <NUM>, the head difference (h) is required to be not more than <NUM>; in a case that the inner diameter (d) is not less than <NUM> and less than <NUM>, the head difference (h) is required to be not more than <NUM>; in a case that the inner diameter (d) is not less than <NUM> and less than <NUM>, the head difference (h) is required to be not more than <NUM>; in a case that the inner diameter (d) is not less than <NUM> and less than <NUM>, the head difference (h) is required to be not more than <NUM>; in a case that the inner diameter (d) is not less than <NUM> and less than <NUM>, the head difference (h) is required to be not more than <NUM>; in a case that the inner diameter (d) is not less than <NUM> and less than <NUM>, the head difference (h) is required to be not more than <NUM>; in a case that the inner diameter (d) is not less than <NUM> and less than <NUM>, the head difference (h) is required to be not more than <NUM>; and in a case that the inner diameter (d) is not less than <NUM> and less than <NUM>, the head difference (h) is required to be not more than <NUM>.

In a case that the second condition is satisfied in the multifunction peripheral <NUM>, a condition for maintaining the meniscus formed in the opening of the nozzle <NUM> is as follows. That is: in a case that the head difference (h) is not more than <NUM>, the inner diameter (d) is required to be not less than <NUM> and less than <NUM> ; in a case that the head difference (h) is greater than <NUM> and not more than <NUM>, the inner diameter (d) is required to be not less than <NUM> and less than <NUM> ; in a case that the head difference (h) is greater than <NUM> and not more than <NUM>, the inner diameter (d) is required to be not less than <NUM> and less than <NUM>; and in a case that the head difference (h) is greater than <NUM> and not more than <NUM>, the inner diameter (d) is required to be not less than <NUM> and less than <NUM>.

In a case that in the multifunction peripheral <NUM>, the specific weight (ρ) of the ink is not less than <NUM>/cm<NUM> and not more than <NUM>/cm<NUM>, the surface tension (σ) of the ink is not less than <NUM> mN/m and not more than <NUM> mN/m, and the contact angle θ defined between the inner surface of the nozzle and the ink is not less than <NUM>° and not more than <NUM>°, the expression (<NUM>) is satisfied and the meniscus formed in the opening of the nozzle <NUM> is maintained, by determining the head difference (h) depending on the inner diameter (d), or by determining the inner diameter (d) depending on the head difference (h), in a similar manner as the case that the second condition is satisfied in the multifunction peripheral <NUM>.

According to the present embodiment, since the inner diameter (d) of the nozzle <NUM> and the head difference (h) satisfy the expression (<NUM>), the surface tension F2 acting upward on the ink in the vicinity of the opening of the nozzle <NUM> is made to be not less than the gravity F1 acting downward on the ink in the vicinity of the opening of the nozzle <NUM>. Accordingly, in the state that the gas layer of the reservoir <NUM> is communicated with the outside, the meniscus of the nozzle <NUM> can be maintained.

In the above-describe embodiment, the inner diameter (d) of the nozzle <NUM> and the head difference (h) are determined under the condition that the maximum storable amount corresponds to the amount when the liquid surface LS of the ink <NUM> is coplanar with the upper end of the atmosphere opening port <NUM>. However, there is no limitation thereto. The maximum storable amount can be set to be any amount not larger than the amount when the liquid surface LS of the ink <NUM> is coplanar with the upper end of the atmosphere opening port <NUM>.

For example, in a case that any mark (for example, drawn line, projection, and the like) is formed (on a sidewall <NUM> of the reservoir <NUM>, for example), the maximum storable amount may be set to be an amount not larger than the amount when the liquid surface LS of the ink <NUM> is coplanar with the upper end of the atmosphere opening port <NUM> and not smaller than the amount when the liquid surface LS of the ink <NUM> is positioned at the height of the mark. In such a case, the inner diameter (d) of the nozzle <NUM> and the head difference (h) are determined based on the set maximum storable amount, and the position of the maximum liquid surface LSmax corresponding to the set maximum storable amount.

The mark may be formed to indicate the height of the ink surface corresponding to the indicated maximum storable amount to the user of the multifunction peripheral <NUM>. Note that, the indicated maximum storable amount is different from the maximum storable amount used for determining the inner diameter (d) etc. For fail-safe design, the indicated maximum storable amount may be smaller than the maximum storable amount and the mark may be formed at a height lower than the maximum liquid surface LSmax of the maximum storable amount.

In the above-described embodiment, although only one piece of the reservoir <NUM> is provided on the recording part <NUM>, it is allowable that a plurality of reservoirs <NUM> are provided on the recording part <NUM>. For example, as depicted in <FIG>, the recording part <NUM> may be provided with four reservoirs 80C, <NUM>, 80Y and 80B.

A cyan ink (not depicted in the drawings) is stored in the reservoir 80C. A magenta ink (not depicted in the drawings) is stored in the reservoir <NUM>. A yellow ink (not depicted in the drawings) is stored in the reservoir 80Y. A black ink (not depicted in the drawings) is stored in the reservoir 80B. The reservoirs 80C, <NUM>, 80Y and 80B are arranged side by side in the left-right direction <NUM>. The atmosphere opening port <NUM> is provided on each of the reservoirs 80C, <NUM>, 80Y and 80B. Note that the reservoirs 80C, <NUM>, 80Y and 80B may be arranged side by side in a direction different from the left-right direction <NUM>, for example, in the front-rear direction <NUM>. Further, the order of arrangement of the reservoirs 80C, <NUM>, 80Y and 80B are not limited to the order depicted in <FIG>. Furthermore, the sizes of the respective reservoirs 80C, <NUM>, 80Y and 80B may be same as one another or different from one another.

In the above-described embodiment, the system by which the head <NUM> records an image on the sheet <NUM> is of the serial head type in which the head <NUM> records the image on the sheet <NUM> while the head <NUM> is being moved by the carriage <NUM>. It is allowable, however, that the system by which the head <NUM> records an image on the sheet <NUM> is of a line head type in which the recording part <NUM> is not provided with the carriage <NUM> and the head <NUM> records the image on the sheet <NUM> without moving. In the case of the line head type, the head <NUM> is provided to span from the right end to the left end of the medium passing area. Further, the conveying operation and the printing operation are executed in parallel and in a continuous manner. Namely, the ink droplets are continuously discharged from the nozzles <NUM> while the sheet <NUM> is (being) conveyed. Further, in the case of the line head type, the head <NUM> is supported by a frame of the casing <NUM>.

In the embodiment, the reservoir <NUM> is installed in the carriage <NUM>, and the ink is replenished by pouring the ink from the inlet port <NUM>. The reservoir <NUM>, however, is not limited to such a configuration. For example, the reservoir <NUM> may be a cartridge which is attachable and detachable with respect to the carriage <NUM>. In such a case, if the amount of the ink stored in the cartridge becomes small, or if the ink is used up, the cartridge is replaced by a new cartridge.

In the embodiment, although the reservoir <NUM> is supported by the carriage <NUM>, it is allowable that the reservoir <NUM> is not supported by the carriage <NUM>. For example, as depicted in <FIG>, it is allowable that the reservoir <NUM> is arranged at a location, which is different from the carriage <NUM>, in the multifunction peripheral <NUM>. In such a case, the reservoir <NUM> and the head <NUM> are connected to each other by a tube <NUM> (an example of a "liquid channel"); the ink <NUM> stored in the reservoir <NUM> is supplied to the head <NUM> via the tube <NUM>, etc. In this case also, at least a part of the reservoir <NUM> is located above the head <NUM>. In this modification, the carriage <NUM> moves while having the head <NUM> mounted thereon, the reservoir <NUM> is not mounted on the carriage <NUM>, and the reservoir <NUM> and the head <NUM> are connected to each other by the tube <NUM>, etc..

In the embodiment, although only the atmosphere opening port <NUM> is provided on the upper wall <NUM> of the reservoir <NUM>, it is allowable that an atmosphere communicating channel <NUM> (an example of a "gas channel") which is continued to the atmosphere opening port <NUM> is further provided on the upper wall <NUM> of the reservoir <NUM>, as depicted in <FIG>.

In an example depicted in <FIG>, the atmosphere communicating channel <NUM> is formed to have a groove shape in the upper wall <NUM> of the reservoir <NUM>, and an upper side of the atmosphere communicating channel <NUM> is closed by a film <NUM>. One end of the atmosphere communicating channel <NUM> is communicated with the gas layer of the reservoir <NUM> via an opening <NUM>. The other end of the atmosphere communicating channel <NUM> is communicated with the outside via the atmosphere opening port <NUM> formed in the upper wall <NUM>. The atmosphere communicating channel <NUM> has a labyrinth structure <NUM> which extends along the left-right direction <NUM> while repeating a U-turn in the front-rear direction <NUM>.

In an example depicted in <FIG>, a semipermeable membrane <NUM> which closes the atmosphere opening port <NUM> is adhered to the atmosphere opening port <NUM> communicating with the other end of the atmosphere communicating channel <NUM>. The semipermeable membrane <NUM> is a porous membrane having minute holes blocking passage of the ink and allowing passage of the gas. For example, the semipermeable membrane <NUM> is formed of a fluorine resin (fluoro-resin) such as a polytetrafluoroethylene, a polychlorotrifluoroethylene, a tetrafluoroethylene-hexafluoropropylene copolymer, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, a tetrafluoroethylene-ethylene copolymer, etc. With this, the ink <NUM> stored in the internal space <NUM> of the reservoir <NUM> is blocked by the semipermeable membrane <NUM>, and thus does not outflow to the outside of the reservoir <NUM> via the atmosphere communicating channel <NUM> and the atmosphere opening port <NUM>. On the other hand, the air is capable of freely moving between the gas layer of the reservoir <NUM> and the outside.

The atmosphere communicating channel <NUM> may have a configuration having the semipermeable membrane <NUM> blocking the atmosphere opening port <NUM> but not having the labyrinth structure <NUM>. As described above, the atmosphere communicating channel <NUM> may be configured to have at least either one of the labyrinth structure <NUM> and the semipermeable membrane <NUM>.

In the embodiment, although any valve unit is not provided on the atmosphere opening port <NUM>, it is allowable that a valve unit is provided on the atmosphere opening port <NUM>. The valve unit is configured to switch the gas layer of the reservoir <NUM> and the outside between a communicated state and a blocked state. In this modification, in a case that the inner diameter (d) of the nozzle <NUM> and the head difference (h) are determined so as to satisfy the expression (<NUM>), the meniscus formed in the opening of the nozzle <NUM> is maintained in a case that the valve unit is in an opened state.

Claim 1:
A liquid discharging apparatus (<NUM>) comprising:
a head (<NUM>) having a nozzle (<NUM>) configured to discharge a liquid (<NUM>);
a reservoir (<NUM>) configured to store the liquid such that the liquid has a liquid surface (LS), and such that the liquid surface is positioned higher than an opening of the nozzle in a state that the reservoir stores the liquid of a maximum storable amount, the maximum storable amount being a maximum amount of the liquid capable of being stored in the reservoir;
characterized by comprising:
an atmosphere port (<NUM>) connecting a gas layer of the reservoir and outside of the reservoir, the gas layer being positioned in the reservoir and above the liquid surface,
wherein an inner diameter d of the nozzle and a head difference h satisfy the expression of phd / σcosθ ≤ <NUM> / g, provided that ρ is a specific weight of the liquid, σ is a surface tension of the liquid, θ is a contact angle of the liquid in the nozzle and g is gravitational acceleration, the head difference h being a difference in height between a meniscus formed in the opening of the nozzle and an upper end of the atmosphere port.