Patent Publication Number: US-6338539-B1

Title: Ink jet recording device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an ink jet printer of the type in which a plurality of ink jet print heads and a plurality of ink cartridges for supplying ink to the print heads are mounted on a carriage movable in the widthwise direction of a printing medium, and the print heads eject ink drops of different colors onto a printing medium in accordance with print data, to thereby print characters and images on the printing medium. More particularly, the invention relates to the technique of replacing ink cartridges. 
     2. Related Art 
     A recording device (referred to simply an a printer) with an ink jet print head has the following advantageous features: relatively low noise is generated at the time of printing, and small dots are formed at high density. Because of these features, the print head is used in a variety of printings inclusive of a color printing. Particularly, with the features of a further improvement of recording density and the capability of the color printing, an ink jet print head in which a black ink print head and a color ink print head are mounted on the carriage is put into practice. To reduce the size of the printer and simplify the ink supplying system, the printer is constructed such that ink cartridges for respectively supplying a black ink and colored inks to the print heads are mounted on the carriage. 
     When the ink cartridges of this type are attached to the carriage, air enters the passages of the print heads through their connection parts. To prevent air from entering, in a printer of the type in which two ink cartridges are mounted on the carriage, the ink cartridge which is to be replaced with a new one is specified by operating a related switch on a panel of the case of the printer, and a negative pressure is applied to the print head, to forcibly charge and discharge ink to and from the print head. 
     The specifying of the replaced ink cartridge depends on the user&#39;s switch operation, if the user mistakenly operates the switch, ink is not charged into the new ink cartridge and the printer fails to print or ink is charged into the ink cartridge that was not replaced, resulting in a wasteful use of ink. 
     To solve these problems, an ink jet printer is proposed in Japanese Patent Laid-Open Publication No. Hei. 7-323576, for example. The printer includes an ink cartridge replacement history judging means for detecting an attaching of the ink cartridge by use of a signal derived from an ink cartridge detecting means. When the attaching of the ink cartridge is detected, ink is charged into the replaced ink cartridge. 
     The proposed printer succeeds in that it allows the ink to be charged into only the replaced ink cartridge, and inhibits the ink from being sucked from the ink cartridges that are not replaced. However, the user per se must specify the ink cartridge to be replaced. Therefore, idle attaching/detaching operations of the ink cartridges are inevitably performed. The result is the entering of air bubbles into the print head and defective printing. 
     The ink jet printer is constructed such that a pressure generating chamber pressurizes the ink to discharge the ink from a discharge orifice. Because of this construction, during shipping the printer must be placed in the same condition as when the printer is operated. To this end, the ink cartridges of the printer are filled with a liquid for shipping, to thereby prevent the print heads from being dried and clogged with dust. 
     For this reason, an initial charging operation is required. In this operation, the shipping liquid is completely removed from the ink cartridges before the first use of the printer, and the ink is charged from the ink cartridge into the associated print head such that the bubbles are completely removed from the print head. A process that is to be carried out when the ink cartridges are first attached to the printer delivered from the factory is performed by the user. Therefore, there is a possibility that the ink is erroneously charged. If the ink charging is erroneous, the printer will fail to perform a normal printing operation, as a matter of course. If the power supply is interrupted during the ink charging operation, the ink charging operation stops in the midst of the charging operation. To return the half-charged state of the print head to its original state, the user must do a complicated restoring manipulation. If he or she fails to correctly perform the manipulation, there is a danger that the recovery from the half-charged state is impossible. 
     SUMMARY OF THE INVENTION 
     According to the present invention, an ink jet recording device comprises an ink jet print head for ejecting different color ink in the form of ink drops; ink cartridges for supplying the ink to the print head; a carriage on which the print head and the ink cartridges are mounted; capping means for sealing the print head, the capping means being located outside a print section; suction means for applying a negative pressure to the capping means; a window allowing the ink cartridges to be exposed in a replaceable fashion; a switch being externally operable; and control means for moving only the ink cartridge to be replaced to a position confronted with the window in a replaceable fashion. With such a construction, when an ink cartridge or cartridges are to be replaced, only the ink cartridge that is to be replaced is selected and automatically moved to a replaceable position. 
     Accordingly, a first object of the present invention is to provide an ink jet recording device with ink cartridges which provide a simplification of the cartridge replacing work and succeed in eliminating erroneous cartridge replacing operations. 
     A second object of the present invention is to provide an ink jet recording device which automatically executes an initial ink charging operation to make the recording device ready for printing. 
     A third object of the present invention is to provide an ink jet recording device in which, even if the supply of electric power is interrupted during the cartridge replacing operation, a process necessary after the power supply interruption is automatically executed in response to the restart of the power supplying, and ink is charged into the print head to make the recording device ready for printing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing an ink jet recording device or printer according to one embodiment of the present invention, the printer being illustrated in a state in which a case cover is open; 
     FIG. 2 is a perspective view showing a recording mechanism of the ink jet printer; 
     FIG. 3 is a block diagram showing a control unit of the ink jet printer; 
     FIG. 4 is a flow chart showing an overall operation of the printer; 
     FIG. 5 is a flow chart showing a power-on process; 
     FIG. 6 is a flow chart showing a cleaning process for a black print head; 
     FIG. 7 is a flow chart showing a cleaning process for a color print head; 
     FIG. 8 is a flow chart showing an operation for checking the amount of ink left in the cartridges; 
     FIG. 9 is a flow chart showing a printing process; 
     FIG. 10 is a flow chart showing a power-off process; 
     FIG. 11 is a flow chart showing the first half of a cartridge replacing process; 
     FIG. 12 is a flow chart showing the second half of a cartridge replacing process; 
     FIGS.  13 ( a ) to  13 ( c ) are diagrams showing states of the head-cartridge-carriage portion in the printer when the carriage is moved to the home position, a replacing position for the color ink cartridge, and a replacing position for the black ink cartridge, respectively; 
     FIGS.  14 ( a ) and  14 ( b ) are diagrams showing positional relationships between the print heads and the capping unit when the carriage is moved to the replacing positions for the color and black ink cartridges, respectively; 
     FIG. 15 is a block diagram showing an ink jet printer according another embodiment of the present invention; 
     FIG. 16 is a flow chart showing a cleaning process for cleaning the printer; 
     FIG. 17 is a flow chart showing an ink cartridge replacing process used for the FIG. 15 printer; and 
     FIGS.  18 ( a ) to  18 ( c ) are diagrams showing other case structures to which the present invention is applicable. 
    
    
     DETAILED DESCRIPTION OP THE PREFERRED EMBODIMENTS 
     FIG. 1 shows an ink jet recording device (such as an ink jet printer) according to one embodiment of the present invention. A case  3  is formed with a case cover  1  that may be opened and closed, and a case body  2 . A printing mechanism to be described later is disposed in the case  3 . To windows  5  and  6  are formed in the case body  2 , and a partitioning portion  2   c  is provided between these windows, so as to partition the case body  2  into a print section and a nonprint section. 
     The window  6  formed in the nonprint section is dimensioned and shaped so that the entire upper surface of either of two ink cartridges  7  and  8  is exposed through the window and at least a part of the upper surface of the remaining ink cartridge is covered by the case body  2 . An operation panel  9  is provided on a portion of the case body  2 , which is not covered with the case cover  1  when it is closed. The operation panel  9  includes a power switch P-SW, ink cartridge replacement switch IC-SW, black head cleaning instruction switch BC-SW, color head cleaning instruction switch CC-SW, line feed switch, reset switch and the like, and ink end indicators BE and CE for black and color ink cartridges, respectively. 
     FIG. 2 shows the printing mechanism of the ink jet printer. A carriage  11  is connected to a carriage drive motor  13  by means of a timing belt  12 . The carriage  11  is horizontally moved in a reciprocative fashion while being guided by a platen  15 . A print head  17  for black ink ejection and another print head  18  for color printing are firmly attached to the carriage  11 . The print head  17  is located in the print section (on the left hand in the figure), while the print head  18  is located in the nonprint section (on the right hand). These print heads confront a printing medium  16 , e.g., a paper. The print heads  17  and  18  receive ink from the black ink cartridge  7  and the color ink cartridge  8 , respectively, and eject ink droplets onto the printing medium  16 . 
     A capping unit  19  is disposed in the nonprint section. In the capping unit  19 , a cap  20  for capping the print head  17  and a cap  21  for capping the color ink print head  18  are mounted on a slider. These caps are coupled with a dual-pump unit  23  that is driven by a motor  22 , by way of tubes, and independently receive negative pressures. 
     The caps  20  and  21  are shaped like caps made of an elastic material, e.g., rubber. Those caps are dimensioned so as to seal the orifice surfaces of the print heads  17  and  18  with closed spaces, respectively. In a nonprint mode, the caps  20  and  21  seal the nozzle surfaces of the print heads  17  and  18 , respectively. In a discharging-capability recovering operation or when the ink cartridges  7  and  8  are replaced with new ones, the dual-pump unit  23  applies negative pressures to those print heads to forcibly discharge the ink from the heads. A cleaning unit  24  is located near the capping unit  19 . The cleaning unit, when driven by a drive source (not shown), presses a wiping blade against the orifice surfaces of the print heads  17  and  18 . 
     FIG. 3 shows an embodiment of a control unit for the ink cartridge replacing operation of the printer and for executing a clogging-removal process. An ink cartridge attachment/detachment detecting means  30  receives signals from switches  31  and  32 , to thereby detect the attachment and detachment of the ink cartridges  7  and  8 . Those switches are to be pressed against the positions on the carriage  11  being confronted with the ink cartridges  7  and  8 , or the cartridge receiving surfaces of the carriage  11  in this embodiment. An ink cartridge replacement judging means  33  receives a signal from the cartridge attachment/detachment detecting means  30 , and judges whether or not the ink cartridge  7  or  8  has been replaced with another in accordance with the received signal. 
     A carriage position detecting means  34  responds to a signal from a carriage position detector  35  and produces a signal on the following positions: at least a home position of the carriage  11 , a first replacement position where the first ink cartridge  7  confronts the window  6 , a second replacement position where the second ink cartridge  8  confronts the window  6 , a flushing position where it receives the ink from the ink cartridges  7  and  8  when the flushing operation is carried out, i.e., positions where it confronts the caps  20  and  21  in this embodiment, cleaning positions where the ink cartridges  7  and  8  may be wiped or rubbed with is the cleaning unit  24 , and the like. 
     A carriage motor control means  36 , under control of a sequence select means  45 , drives the carriage drive motor  13  through a CR (carriage) motor drive means  47  to reciprocatively move the carriage  11  for printing. Further, the carriage motor control means  36  receives signals from a suction control means  39  to be described later and the carriage position detecting means  34 , and moves the carriage  11  to the home position, first replacement position, second replacement position, flushing position, and the cleaning position in accordance with those received signals. When the replacing of the ink cartridge  7  or  8  is normally completed, the carriage motor control means  36  moves the carriage  11  to the home position by a lower torque or at a lower speed than in a normal state or a combination of them. 
     A print/flushing control means  37  receives print data from a host computer, and in accordance with the print data, causes a head drive means  38  to output a drive signal to the print heads  17  and  18  which in turn eject ink droplets or drops. When the print heads  17  and  18  are put at the flushing positions, the print/flushing control means  37  outputs a drive signal to those print heads by way of the head drive means, whereby the print heads discharge ink drops through all their discharging orifices. By the discharging operation of ink drops, ink of increased viscosity is discharged into the ink receiver. 
     The suction control means  39 , under control of the sequence select means  45 , outputs a control signal to a pump drive means  40 . In accordance with the control signal, the capping unit  19  caps the print heads  17  and  18  with the caps, and suction forces and suction times of the suction pumps  23   a  and  23   b  of the dual-pump unit  23  are controlled so as to cause the print heads  17  and  18  to discharge ink for the recovery of their ink discharging capabilities. Further, when the ink cartridges  7  and  8  are replaced with new ones, the suction control means  39  causes the ink cartridges  7  and  8  to charge inks to the print heads  17  and  18 . 
     An ink level detecting means  41  integrates the number of printed dots, the number of ink drops discharged in the flushing operation, and the amount of ink consumed in the ink charging operation and cleaning operation, and computes an ink level of inks still left in the ink cartridges  7  and  8  on the basis of the result of the integration. When the ink cartridges  7  and  8  are replaced with new ones, the ink level detecting means  41  resets the integrated values. When an instruction to replace at least one of the ink cartridges  7  and  8  is issued, the ink level detecting means  41  checks an ink level of the ink left in the other ink cartridge. When the amount of the ink left is less than the amount of ink consumed by the sucking operation carried out at the time of the cartridge replacement, the ink level detecting means  41  judges that the ink level of the ink left in the ink cartridge  7  or  8  is an ink end level. 
     A power-off detecting means  42  detects an “on” or “off” state of a power switch P. When the power source is turned off, the power-off detecting means  42  executes a predetermined process and stops the supply of electric power to the printer. A case opening detecting means  43  receives a signal derived from a switch  44 , which operates responsive to the opening/closing of the case cover  1 , and produces a signal indicative of an opening/closing of the case cover  1 . 
     The sequence select means  45  receives signals from the ink cartridge replacement switch IC, black head cleaning instruction switch BC, and the color head cleaning instruction switch CC on the panel  9 , the power-off detecting means  42 , case opening detecting means  43 , ink level detecting means  41 , and the host computer, and supervises the operations on an overall process, power-on process, power-off process, cleaning process, ink level check process, print process, ink cartridge replacement process, and the like in accordance with flow charts to be described later. Further, the sequence select means  45  stores various statuses ensuring from the ink cartridge replacement into a suction status storing means  46  when the power off process is executed. 
     The suction status storing means  46  stores data to set an initial charging flag to an off state when the printers are delivered from factories. When a user receives the printer and completes an initial ink charging, the initial charging flag is set to an on state. The suction status storing means  46  further includes memory areas for stowing statuses of the suction operations fox the ink cartridges  7  and  8 , statuses of replacements of the ink cartridges  7  and  8 , and the amount of ink left in the ink cartridges. 
     The operations of the printer thus constructed will be described with reference to the flow charts shown in FIGS. 4 to  12 . 
     A. Description on the Overall Operation 
     When the power switch P is turned on, the sequence select means  45  executes a power-on process (step S 100 ). 
     To be more specific, as shown in FIG. 5, the sequence select means  45  reads a suction status of the previous power-off from the suction status storing means  46  (step S 112 ). Further, it judges whether or not the black ink cartridge  7  or the color ink cartridge  8  is attached to the carriage on the basis of the signal from the ink cartridge replacement judging means  33  (step S 113 ). When neither the black ink cartridge  7  nor the color ink cartridge  8  is attached to the carriage, the sequence select means  45  causes the indicators BE and CB to indicate no ink cartridge (step S 114 ), and starts a sequence of an ink cartridge replacing process to be described later (step S 115 ). 
     When the black ink cartridge  7  and the color ink cartridge  8  are both attached to the carriage  11 , the sequence select means  45  executes a process for checking the amount of ink left in the ink cartridges  7  and  8  on the basis of the data from the ink level detecting means  41  (step S 116 ). 
     If the amount of ink left in one of the ink cartridges  7  and  8  is extremely small so as to be indicative of an ink end (step S 117 ), the sequence select means  45  starts a sequence of the cartridge replacing process (step S 115 ). 
     When sufficient amounts of ink are left in the ink cartridges  7  and  8 , the sequence select means  45  judges the ending of the cartridge replacing work of the ink cartridges  7  and  8  on the basis of the data stored in the suction status storing means  46 . To be more specific, when the power switch P has been turned off before the ink cartridges  7  and  8  have been replaced in a faultless manner (step S 114 ), the sequence select means  45  starts again the ink cartridge replacing work (step S 115 ) or executes the suction process after the replacement of the ink cartridges  7  and  8 . 
     When the cartridge replacing work ends in a faultless manner, the sequence select means  45  checks if the case cover  1  is opened on the basis of the signal from the case opening detecting means  43  (step S 119 ). When the case cover  1  is opened, the sequence select means  45  carries out the cartridge replacing process (step S 115 ). As a result, the sequence of the cartridge replacing process is automatically read out by opening the case cover  1  immediately after the power on or turning on the power switch P after the case cover  1  is opened. 
     The sequence select means  45  judges whether or not the initial charging of ink ends on the basis of the data from the suction status storing means  46  (step S 120 ). If it does not end, i.e., the ink has never been charged into the print heads  17  and  18 , the sequence select means  45  executes the sucking process for the initial charging (step S 121 ), and stores the data to set the initial charging flag to an on state in the suction status storing means  46  (S 122 ), to thereby prevent the initial charging operation consuming a large mount of ink from being mistakenly performed. 
     In a state that the attaching of the ink cartridges  7  and  8  is completed, when a timer suction process, which is for removing the orifice clogging, which is possibly caused when the printer is not used for a long time, starts (S 123 ), the sequence select means  45  executes the suction timer process in a manner that a quantity of suction is set to be relatively large (S 125 ) when the timer suction process is first carried out after the replacement of the ink cartridges  7  and  8  (S 124 ), and it is set to be relatively small when the suction timer process has already been carried out (S 126 ). 
     With this process, of the air bubbles having entered into the print heads  17  and  18  through the replacing operation of the ink cartridges  7  and  8 , the bubbles that are still left after the sucking operation performed at the time of cartridge replacement and which subsequently grow are completely removed. Therefore, the suction quantity required merely for the clogging prevention or removal is minimized, to thereby save the ink. 
     When the power on process ends, the sequence select means  45  detects operation states of the switches on the operation panel  9 . If the cleaning instruction switches BC and CC are operated (S 101  and S 103  in FIG.  4 ), the sequence select means  45  carries out a cleaning process for the black ink print head  17  and another cleaning process for the color ink print head  18  (S 102  and S 104 ), both processes being described later. When the ink cartridge replacement switch IC is operated (S 105 ), the sequence select means  45  starts a sequence of a cartridge replacing process to be described later (S 106 ). 
     When the supply of electric power still continues (S 107 ) after the processes corresponding to the operations instructed by the switches on the operation panel  9 , the sequence select means  45  waits for the incoming print data from the host computer (S 109 ). When any of the switches on the operation panel  9  is depressed, the sequence select means  45  executes the steps S 101  to S 106 . When the printer, which is in a ready-for-printing state, receives print data, the sequence select means  45  checks the amount of ink left in the ink cartridges  7  and  8  (S 111 ) while executing a printing process to be described later (S 110 ), and returns to the first step S 101 . 
     B. Cleaning Process for the Black Ink Print Head 
     When the black head cleaning instruction switch EC for the black ink print head  17  is operated on the operation panel  9 , the sequence select means  45  checks the amount of the ink left in the black ink cartridge  7  on the basis of the data from the sequence select means  45 . If the black ink cartridge  7  is in an ink end state (S 127  in FIG.  6 ), the sequence select means  45  starts the sequence of the replacing process for the black ink cartridge  7  (S 129 ), and blinks the ink end indicator BE to indicate the ink end. 
     When the amount of the residual ink in the black ink cartridge  7  is enough to print but less than a predetermined value of the ink amount, i.e., an amount of the ink that will be consumed by the ink suction during cleaning so as to be insufficient for the printing (S 128 ), the sequence select means  45  starts the sequence of the replacing process for the black ink cartridge  7  in order to eliminate an unwanted situation in which, as the result of discharging of the ink, air bubbles enter the black ink cartridge  7  (S 129 ). 
     When the amount of the ink left in the black ink cartridge  7  is at least half of the ink amount before the replacement of the ink cartridge and a quantity of printing is less than a reference value after the ink cartridge is replaced (S 130 ), the sequence select means  45  executes a special suction process for removing the bubbles entered at the time of the cartridge replacement (S 131 ). In the special suction process for bubble discharging, the sequence select means  45  resets the residual ink amount in the ink level detecting means  41 , switches a one-time flag to an on state, and executes a suction process as executed after the ink cartridge replacement. For a cleaning instruction by the user when a predetermined quantity of printing, e.g., five (5) pages or larger, has been made after the ink cartridge replacement, the sequence select means  45  sets the one time flag to an off state, and executes a normal suction process consuming a smaller amount of auction ink. For a cleaning instruction when the quantity of the printing in less than the predetermined quantity, the sequence select means  45  sets the one time flag to an on state and executes the special suction process for bubble removal. 
     When the amount of the ink left in the black ink cartridge  7  is large and enough ink will be left after the cleaning, or when a new black ink cartridge  7  is attached, the sequence select means  45  moves the black ink print head  17  to its home position, caps it with the capping unit  19 , and causes the suction control means  39  to control the auction pump  23   a  so as to suck the ink from the black ink print head  17  for its discharging (S 123 ). 
     C. Cleaning Process for the Color Ink Print Head 
     When the color head cleaning instruction switch CC for the color ink print head  18  is operated on the operation panel  9 , the sequence select means  45  checks the amount of ink left in the color ink cartridge  8  on the basis of the data from the sequence select means  45 . If the residual ink level is an ink end level (S 133  in FIG.  7 ), the sequence select means  45  starts the sequence of the replacing process for the color ink cartridge  8  (S 135 ). 
     When the amount of the residual ink in the color ink cartridge  8  is enough to print but less than a predetermined value of the ink amount, e.g., in a near end level, i.e., an amount of the ink that will be consumed by the ink suction during cleaning so as to be insufficient for the printing (S 134 ), the sequence select means  45  starts the sequence of the replacing process for the color ink cartridge  8  in order to eliminate an unwanted situation in which, as the result of discharging of the ink, air bubbles enter the color ink cartridge (S 137 ). 
     In the special bubble removal suction process, the sequence select means  45  resets the residual ink amount in the ink level detecting means  41 , switches a one-time flag to an on state, and executes a suction process as executed after the ink cartridge replacement. For a cleaning instruction by the user when a predetermined quantity of printing, e.g., five (5) pages or larger, has been made after the ink cartridge replacement, the sequence select means  45  sets the one time flag to an off state, and executes a normal suction process consuming a smaller amount of suction ink. For a cleaning instruction when the quantity of the printing is less than the predetermined quantity, the sequence select means  45  sets the one time flag to an on state and executes the special suction process for bubble removal. 
     When the amount of the ink left in the color ink cartridge  8  is large and enough ink to print will be left after the cleaning, or when a new color ink cartridge  8  is attached, the sequence select means  45  moves the color ink print head  18  to its home position, caps it with the capping unit  19 , and causes the suction control means  39  to control the suction pump  23   a  so as to suck the ink from the black ink print head  17  for its discharging (S 138 ). 
     When the suction process is completed, the sequence select means  45  causes the cleaning unit  24  to rub the nozzle plates, if required, and moves the print heads  17  and  18  to the capping unit  19 , and causes the print/flushing control means  37  to perform a flushing operation. 
     D. Detection of the Amount of Residual Inks 
     When a time to check the amount of residual ink is reached, the sequence select means  45  judges whether or not the amount of the ink left in one of the ink cartridges, e.g., the black ink cartridge  7 , is at an ink end level on the basis of the data from the ink level detecting means  41  (S 139  in FIG.  8 ). If it is at an ink end, the sequence select means  45  causes the ink end indicator BE to blink to indicate a black ink end (S 140 ). Subsequently, the sequence select means  45  checks the amount of the ink left in the other ink cartridge, i.e., the color ink cartridge  8  in this embodiment. If the result shows that it is not at the ink end level, but not less than an amount of the ink that will be consumed by the ink suction in the cleaning (S 141 ), the sequence select means  45  judges that the amount of the residual ink is at an ink end level (S 142 ), and causes the ink end indicator CE for the color ink cartridge  8  to blink to indicate the ink end (S 143 ). 
     When a sufficient amount of ink is left in the black ink cartridge  7  which was first checked for its ink amount left therein, the sequence select means  45  repeats a sequence of the steps similar to the above-mentioned one for the color ink cartridge  8  (S 144  to S 148 ). That is, the sequence select means  45  checks if the amount of the ink left in the color ink cartridge  8  is in at ink end level, and if it is at the ink end level, the sequence select means  45  causes the ink end indicator CE to blink (S 145 ). Subsequently, the sequence select means  45  also checks the amount of the ink left in the black ink cartridge  7 . If it is not at the ink end level, but is extremely small and not less than an amount of the ink that will be consumed by the ink suction in the cleaning (S 146 ), the sequence select means  45  judges that the amount of the residual ink is at an ink end level (S 147 ). and causes the black ink end indicator BE for the black ink cartridge  7  to blink to indicate the ink end (S 148 ). 
     When the amount of the ink left in one of the ink cartridges is reduced to such an extent as to require the replacement of the ink cartridge with a new one, the sequence select means  45  checks the amount of the ink left in the other ink cartridge as well as that in the first ink cartridge. If the result shows that the residual ink amount is enough to print but less than a predetermined value of ink amount necessary for the suction operation, the sequence select means  45  judges that the residual ink amount is at the ink end level. This creates an advantage in a printer with the print heads constructed as shown in FIG.  15 . As shown, in the FIG. 15 print heads, a single nozzle plate is used commonly to both the print heads, and therefore it is impossible to independently seal the orifice arrays of different inks. That is, the print heads are sealed with a single cap  51 . In this type of the print heads, ink is sucked from the ink cartridge containing a sufficient amount of ink therein as well as the ink cartridge whose residual ink is at the ink end level. In other words, the ink is wastefully used. There is a chance that when one of the ink cartridges is replaced with a new one, the ink left in the other ink cartridge has been almost completely consumed and is at a near end level. An additional replacement of the ink cartridge must be done in the immediate future. 
     If the sequence select means, upon the above judgement, calls upon the user to replace one ink cartridge and the other ink cartridge as well, a single suction operation will suffice for both ink cartridges. The result is the simplification of the replacing work of the ink cartridges and the lessening of the ink consumption. 
     When it is confirmed that the amount of ink left in the two ink cartridges  7  and  8  is greater than an ink quantity which leads to the judgment of the ink end, the ink level detecting means  41  judges whether or not the amount of the ink in the black ink cartridge  7  is at the near end level (S 149 ). If it is at the near end level, the sequence select means causes the ink end indicator BE to blink, to thereby inform the user that the residual ink amount of the black ink cartridge  7  is at the near end level (S 150 ). 
     When a sufficient amount of ink is left in the black ink cartridge  7 , the sequence select means judges whether or not the amount of ink in the color ink cartridge  8  is at the near end level (S 151 ). If it is at the near end level, the sequence select means causes the ink end indicator CE to blink to inform the user that the ink left in the color ink cartridge  8  is at the near end level (S 152 ). 
     E. Printing Process 
     When print data is received and the printer is ready for printing, the sequence select means  45  checks the amount of ink left in the ink cartridges  7  and  8  on the basis of the data from the ink level detecting means  41  (S 153  in FIG.  9 ), and if necessary, sends the residual ink amount data to the host computer (S 154 ). 
     The host computer computes the amount of ink necessary for the print data to be used for the printing, and compares the necessary ink amounts with the residual ink amount data received. If the amount of ink left in the ink cartridges  7  and  8  is less than the necessary amount of ink, the host computer issues a cartridge replacement instruction (S 155 ), or displays an error on the display means of the host computer to urge the user to continue the printing operation or to make the replacement of the ink cartridge or cartridges. If the user chooses the ink cartridge replacement, the host computer sends a cartridge replacement instruction to the printer. Upon receipt of the instruction, the sequence select means  45  starts the sequence of the ink cartridge replacement process (S 157 ). When the data from the ink level detecting means  41  shows that the ink in the cartridges is at the ink end level (S 156 ), the sequence select means  45  starts the sequence of the ink cartridge replacement process (S 157 ). 
     When the printer passes the check of the residual ink amounts of the ink cartridges  7  and  8 , or when the ink cartridges  7  and  8  are replaced with new ones and the printer is ready for printing, the sequence select means  45  transfers the print data received from the host computer to the print/flushing control means  37 , whereby the printing of one page is performed (S 158 ). When the print data of two or more pages is present, the sequence select means executes the process steps (S 153  to S 158 ) and the printing of the next and subsequent pages is carried out (S 159 ). 
     Eventually, the printing operation ends, and the user gives an off instruction to the printer by use of the power switch P (S 107  in FIG.  4 ). The power-off detecting means  42  outputs a signal, and the sequence select means  45  executes the power-off process (S 108 ). 
     P. Power-Off Process 
     When the power switch P is turned off and the power-off detecting means  42  produces a signal, the sequence select means  45  drives the carriage motor control means  36  which in turn moves the case cover  1  to the home position (S 160  in FIG.  10 ). As a result, the print heads  17  and  18  are capped with the caps  20  and  21 , to thereby prevent the ink in the discharge orifices of the print heads  17  and  18  from drying out. 
     In a case where the present operation of the printer is the first time operation after the ink cartridges are first attached to the carriage, and the initial charging of ink is performed, the sequence select means judges whether or not the initial charging operation has been performed in a faultless manner. If it has been performed faultlessly, the sequence select means changes a state of the initial charging flag from an off state to an on state. In a case where the initial charging operation has been completed and the ink cartridges  7  and  8  are replaced with new ones for the purpose of merely supplying the ink, data indicative of the replacement of the ink cartridges, data indicating as to whether or not the suction process following the ink cartridge replacement in faultlessly completed, and residual ink amount data from the ink level detecting means  41  are stored into the auction status storing means  46  (S 161 ). After all the data indicating the present status are stored, the supply of electric power to the printer is stopped. 
     G. Ink Cartridge Replacing Process 
     When the ink cartridge replacement switch IC on the operation panel  9  is operated or the sequence of the cartridge replacing process is started through the execution of the above-mentioned process steps the sequence select means  45  judges whether, of the two ink cartridges  7  and  8 , which are arranged side by side in the moving direction of the carriage  11 , only the ink cartridge  7  disposed in the print section of the printer case body is to be replaced or both the ink cartridges  7  and  8  are to be replaced (S 162  and S 163  in FIG.  11 ). 
     When both the ink cartridges  7  and  8  are to be replaced, the sequence select means  45  causes the carriage motor control means  36  to move the carriage  11 , which is at the home position (FIG.  13 ( a )), to the print section, whereby the color ink cartridge  8  attached to the portion of the carriage  11  located in the nonprint section is moved to the replacing position, i.e., the position confronted with or right under the window  6  (FIG.  13 ( c ), FIG.  14 ( b )). 
     In this state, only the color ink cartridge  8  is confronted with the window  6 , and the black ink cartridge  7  is confronted with the partitioning portion  2   c . This state of the printer allows the user to detach only the color ink cartridge  8  from the carriage. Therefore, it is easy to specify the ink cartridge to be replaced, including the black ink cartridge  7 , and hence there is no chance that the user mistakenly pulls out another ink cartridge, i.e., the ink cartridge that does not need to be replaced. 
     When the color ink cartridge  8  in the window  6  is pulled out, the switch or detector  32  detects the pulling-out of the color ink cartridge  8  and produces a signal indicative of that. When a new ink cartridge  9  is attached to the carriage  11 , the same detector detects the attachment of the ink cartridge and produces a signal indicative of that. In response to this signal, the sequence select means  45  stores the replacement of the ink cartridge  8  into the suction control means  39  (S 164 ). 
     When the user presses the ink cartridge replacement switch IC (S 166 ) within a preset time after the attaching of the new color ink cartridge  8 , or after the preset time elapses, judgement is automatically made as to if only one cartridge is to be replaced (S 167 ). 
     In the present case, two ink cartridges  7  and  8  are to be replaced. Therefore, the sequence select means  45  outputs a signal to the carriage motor control means  36  to move the print head  18  now coupled with the new color ink cartridge  8  to the wiping position where the nozzle plate of the print head is wiped with the cleaning unit  24  (S 168 ). As the result of the attaching/detaching of the color ink cartridge  8 , ink frequently oozes out of the discharge orifices. However, this ink is wiped out through the wiping operation, to thereby prevent the ink from dropping. 
     When the replacement of the color ink cartridge  8  located in the nonprint section is completed, the sequence select means  45  causes the carriage motor control means  36  to move the carriage  11 . With the movement of the carriage, the black ink cartridge  7  is moved to the cartridge replacing position, i.e., the position confronted with the window  6  (S 169 ) (FIG.  13 ( b ), FIG.  14 ( a )). As the result of this movement, the print head  18  having undergone the first replacement of the color ink cartridge  8  is retracted to the home position. Therefore, if the ink drops due to the replacement of the color ink cartridge  8 , the print section is not soiled with the dropped ink. 
     When the ink cartridge  7  is pulled out for replacement, the switch or detector  32  detects the pulling-out of the ink cartridge  7  and produces a signal indicative of that. When a new ink cartridge  7  is attached to the carriage  11 , the same detector detects the attachment of the ink cartridge and produces a signal indicative of that. In response to this signal, the sequence select means  45  stores the replacement of the ink cartridge  7  into the suction control means  39  (S 170 ). 
     When the user presses the ink cartridge replacement switch IC (S 172 ) within a preset time (S 171 ) after a new ink cartridge is attached to the carriage, or after the preset time elapses, the sequence select means  45  causes the carriage motor control means  36  to drive the carriage drive motor  13  to turn by a low torque or at such a low speed as to cause the movement of the carriage to be appreciated by the user, or to move the carriage by a low torque and at low speed (S 173 ). In this way, the carriage  11  is initialized (S 174 ). 
     The user sees the low-torque and low-speed movement of the carriage  11 , and understands from this that the printer operation has shifted to the next phase. The user will therefore know to pull his or her fingers away from the case  3 . Therefore, the user will never have his finger caught by the machine. If the user&#39;s finger is caught by the machine, the carriage drive motor  13  will instantly be stopped since its drive torque is relatively small. Therefore, the carriage  11  is not damaged and the user&#39;s finger is not hurt. Further, even if an external force acts on the carriage  11  in the cartridge replacement work and the carriage  11  is forcibly moved, the carriage  11  can be moved to a position suitable for printing. 
     Thus, the carriage  11  has been moved to such a position as to avoid the user&#39;s finger being caught by the machine, i.e., in this embodiment, the black ink cartridge  7  located in the print section has been moved to a position where the side of the cartridge closer to the nonprint section is out of the area defined by the window  6 . If the carriage position detecting means  34  detects the movement of the carriage  11 , the carriage motor control means  36  drives the carriage drive motor  13  to turn by a normal torque and at a predetermined speed, to thereby move the print head  18  to such a position as to allow the capping unit  19  to seal the print head  18  (S 175 ). 
     The sequence select means  45  judges whether or not the initial ink charging operations for the print head ( 17 ,  18 ) are completed, on the basis of the data of the suction status storing means  46  (S 176 ). In a case where the present attachment of the ink cartridge is a first time attachment after the user procures the printer, i.e., the initial charging flag in the suction status storing means  46  is in an off state, the sequence select means  45  produces a signal for transmission to the suction control means  39  to operate the pump ( 23   a ,  23   b ). The pump sucks, from the print head ( 17 ,  18 ), an amount of ink necessary for the initial charging, i.e., the amount of ink used for discharging the maintenance liquid, which was charged into the print head ( 17 ,  18 ) at the factory, and for completely removing the air bubbles from the print head to make the print head ready for printing (S 177 ). Then the sequence select means  45  confirms that the initial charging operation is faultlessly completed, and switches the initial charging flag from an off state to an on state, the flag being stored in the suction status storing means  46  (S 178 ). 
     When the attachment of the ink cartridge ( 7 ,  8 ) is merely for the resupply of the ink (S 180 , S 183  in FIG.  12 ), the sequence select means  45  sends a signal to the auction control means  39  to operate the pump ( 23   a ,  23   b ). The pump sucks the amount of ink required when the cartridge replacement is made, from the ink cartridge ( 17 ,  18 ) (S 181 , S 184 ). The home position is detected by the carriage position detecting means  34 , and the carriage  11  is stopped at the home position. The print head ( 17 ,  18 ) is capped by the capping unit  19  (S 185 ), and the fact that the ink is cartridge ( 7 ,  8 ) has been replaced faultlessly is stored in the suction status storing means  46  (S 186 ). 
     In a case where one ink cartridge is replaced (S 162  in FIG.  11 ), the sequence select means  45  causes the carriage motor control means  36  to move the carriage  11 . With the movement of the carriage, the ink cartridge  7  or  8  to be replaced is set at the window  6  position as the replacing position (S 179 ) (FIGS.  13 ( b ) and  13 ( c ), and FIGS.  14 ( a ) and  14 ( b )). 
     Then, when replacing the ink cartridge ( 7  or  8 ), the cartridge is pulled out, and the pulling-out of the cartridge is detected by the detector ( 31  or  32 ). When the ink cartridge is attached to the carriage  11 , the attachment is detected by the same detector. Therefore, the sequence select means  45  stores the replacement of the ink cartridge ( 7  or  8 ) in the suction control means  39  (S 170  in FIG.  11 ). 
     When the user presses the ink cartridge replacement switch IC (S 172 ) within a preset time (S 171 ) after a new ink cartridge is attached to the carriage, or after the preset time elapses without pressing the switch IC, the sequence select means  45  causes the carriage motor control means  36  to drive the carriage drive motor  13  to turn by a low torque or at such a low speed as to cause the movement of the carriage to be appreciated by the user, or to move the carriage by a low torque and at low speed (S 173 ). In this way, the carriage  11  is initialized (S 174 ). 
     Thus, the carriage  11  has been moved to such a position an to prevent the user&#39;s finger from being caught by the machine, i.e., in this embodiment, the black ink cartridge  7  located in the print section has been moved to a position where the side of the cartridge closer to the nonprint section is out of the area defined by the window  6 . If the carriage position detecting means  34  detects the movement of the carriage  11 , the carriage motor control means  36  drives the carriage drive motor  13  to turn by a normal torque and at a predetermined speed, to thereby move the print head  18  to such a position as to allow the capping unit  19  to seal the print head  18  (S 175 ). 
     The sequence select means  45  judges whether or not the initial ink charging operation for the print head ( 17  or  18 ) is completed, on the basis of the data of the suction status storing means  46  (S 176 ). In a case where the present attachment of the ink cartridge is the first time attachment after the user procures the printer, i.e., the initial charging flag in the suction status storing means  46  is in an off state, the sequence select means  45  produces a signal for transmission to the suction control means  39  to operate the pump ( 23   a  or  23   b ). The pump sucks from the print head ( 17  or  18 ) an amount of ink necessary for the initial charging, i.e., the amount of ink used for discharging the maintenance liquid, which was charged into the print head ( 17  or  18 ) at the factory, and for completely removing the air bubbles from the print head to make the print ready for printing (S 177 ). Then, the sequence select means  45  confirms that the initial charging operation is faultlessly completed, and switches the initial charging flag from an off state to an on state, the flag being stored in the suction status storing means  46  (S 178 ). 
     When the attachment of the ink cartridge ( 7  or  8 ) is for the resupply of ink (S 180 , S 183  in FIG.  12 ), the sequence select means  45  sends a signal to the suction control means  39  to operate the pump ( 23   a  or  23   b ). The pump sucks the amount of ink required when the cartridge replacement is made, from the ink cartridge ( 17  or  18 ) (S 181 , S 184 ). 
     Following the sucking operation, the sequence select means  45  moves the carriage  11  to the flushing position, and causes the print/flushing control means  37  to flush the print head ( 17  or  18 ) whose cartridge ( 7  or  8 ) is not replaced. By the flushing operation, ink with an increased viscosity is discharged from the print head, to thereby prevent the clogging of the print head orifices, and to repair the broken meniscuses in the discharging orifices (S 184 , S 182 ). 
     When those operations end, the home position is detected by the carriage position detecting means  34 , and the carriage  11  is stopped at the home position. The print head ( 17  or  18 ) is capped by the capping unit  19  (S 185 ), and the fact that the ink cartridge ( 7  or  8 ) has been replaced faultlessly is stored in the suction status storing means  46  (S 186 ). 
     If, during the work of replacing of the ink cartridge ( 7  or  8 ), the power switch P is mistakenly turned off, the sequence select means  45  receives a signal from the power-off detecting means  42  to select the power off process (FIG.  10 ), and stores into the suction status storing means  46 , data indicative of the completion of the initial charging operation, cartridge replacement status, and completion of sucking operation resulting from the cartridge replacement, data of the ink level detecting means  41 , and the like. 
     The storage of the data in the suction status storing means  46  provides the following advantage. For example, when the power switch P is mistakenly turned off during the cartridge replacement work, the power on process (FIG. 5) executes again the process interrupted when the power switch P is turned off before the printing operation starts, and sets the print heads  17  and  18  to be ready for printing. 
     In this embodiment, the carriage  11  is moved to the window  6  position in a priority order of the following cases: 1) it is ascertained that a plural number of ink cartridges are to be replaced; 2) it is detected that the ink cartridge  7 ,  8  is not attached; 3) it is detected that the amount of ink in the ink cartridge  7 ,  8  is at an ink end level; 4) it is detected that the amount of ink in the ink cartridge  7 ,  8  is at a near end level; and  5 ) it is detected that the ink cartridge  7 ,  8  contains a sufficient amount of ink for printing. Therefore, the ink cartridge  7 ,  8  may be replaced in accordance with the indication of the ink end indicator BE, CE. The trouble tending to occur in the replacing work of plural ink cartridges can be avoided. 
     The present invention can be applied to a print head system of the type in which two print heads  7  and  8  are used, and a single nozzle plate is used for both print heads, so that it is impossible to independently seal the discharging orifice arrays of different color inks. As shown in FIG. 15, a print head  50  is capped with a single cap  51 , and a single suction pump  52  is used for the initial ink charging and the suction for the replacement. Further, a single end indicator IE is used. 
     H. Cleaning Process for the Print Heads 
     When the color head cleaning instruction switch CC for the print head  50  is operated on the operation panel  9 , the sequence select means  45  checks the amount of ink left in the black ink cartridge  7  on the basis of the data from the ink level detecting means  41 . If the ink is at an ink end level (S 190  in FIG.  16 ), the sequence select means  45  checks the amount of ink left in the color ink cartridge  8 . If the check result shows that the amount of the residual ink is in excess of the amount of ink consumed by the ink suction in the cleaning operation (S 191 ), the sequence select means  45  starts the process of replacing the black ink cartridge (S 192 ). If the amount of the residual ink is less than the amount of ink consumed by the ink suction in the cleaning operation, the sequence select means  45  starts the process for replacing both ink cartridges  7  and  8  (S 193 ). 
     When the amount of ink left in the black ink cartridge  7  is greater than the ink amount at the ink end level, but less than the amount of ink consumed by the ink suction in the cleaning operation (S 194 ), the sequence select means  45  checks the amount of the ink left in the color ink cartridge  8 . If the check result shows that the residual ink amount is greater than the amount of ink consumed by the ink suction in the cleaning operation (S 191 ), the sequence select means  45  starts the process for replacing the black ink cartridge (S 192 ). If the residual ink amount is leas than the amount of ink consumed by the ink suction in the cleaning operation, the sequence select means  45  starts the process for replacing both the ink cartridges  7  and  8  (S 193 ). 
     If the residual ink amount of the black ink cartridge  7  is greater than the amount of ink consumed by the ink suction in the cleaning operation (S 194 ), the sequence select means  45  judges that the amount of the ink in the color ink cartridge  8  is at an ink end level (S 195 ), on the basis of the data of the previous residual ink amount check operation for the color ink cartridge  8  (S 191 ). When the residual ink amount is less than the amount of ink consumed by the ink suction in the cleaning operation (S 196 ), the sequence select means  45  starts the process for replacing the color ink cartridge  8  (S 197 ). 
     In this way, it is ascertained that the amount of ink left in the ink cartridges  7  and  8  in greater than the amount of ink consumed by the ink suction in the cleaning operation. If the sequence select means  45  refers to the data of the ink level detecting means  41  and recognizes that the amount of ink left in the ink cartridges  7  and  8  is at least ½ after the ink cartridges are both replaced, and the amount of printing is less than a predetermined value of the ink amount after the cartridge replacement, the sequence select means  45  executes the special bubble discharging process (S 199 ). If the residual ink amounts and the printing amount are different from those in the above case, the sequence select means  45  executes the suction process (S 200 ). 
     I. Cartridge Replacement Process 
     When the sequence of the ink cartridge replacement process is started by the operating the ink cartridge replacement switch IC on the operation panel  9  or by each process mentioned above, the sequence select means  45  causes the carriage motor control means  36  to move the carriage  11 , which is at the home position, to the position for replacing the ink cartridges  7  and  8  in the print section (S 201  in FIG.  17 ). 
     When the ink cartridge  8  is pulled out, the detector  32  detects the pulling-out of the cartridge, and produces a signal. When the ink cartridge  8  is attached to the carriage  11 , the same detector detects the cartridge attachment and produces a signal. Therefore, the sequence select means  45  stores the replacement of the ink cartridge  8  in the suction control means  39  (S 202 ). 
     When a preset time elapses (S 203 ) after a new color ink cartridge  8  is attached to the carriage, or the user presses the ink cartridge replacement switch IC (S 172 ) within the preset time after the attachment of the new cartridge (S 204 ), the sequence select means  45  causes the carriage motor control means  36  to drive the carriage drive motor  13  to turn by a low torque or at such a low speed as to cause the movement of the carriage to be appreciated by the user, or to move the carriage by a low torque and at low speed (S 205 ). In this way, the sequence select means  45  executes the initializing process of the carriage position (S 206 ). Therefore, even if an external force acts on the carriage  11  in the cartridge replacement work and the carriage  11  is forcibly moved, the carriage  11  can be moved to a position suitable for printing. 
     The sequence select means  45  judges whether the cartridge replacement is a first time replacement after the printer is procured, or whether it is for the resupply of ink, and selects the auction mode (S 208 ). 
     If the cartridge replacement is a first time replacement after the printer is procured, i.e., the initial charging flag in the suction status storing means  46  is in an off state, the sequence select means  45  produces a signal for transmission to the suction control means  39  to operate the suction pump  52  which sucks from the print heads  17  and  18  the amount of ink-necessary for the initial charging, i.e., the amount of ink for discharging the maintenance liquid, which was charged into the print heads at the factory, and for completely removing the air bubbles from the print head  150  to make the print head ready for printing. If the cartridge replacement is for the resupply of ink, the suction status storing means  46  performs a normal suction operation (S 209 ). 
     When those operations end, the home position is detected by the carriage position detecting means  34 , and the carriage  11  is stopped at the home position (S 210 ). The print head  150  is capped with the cap  51  of the capping unit, and the fact that the ink cartridge ( 7  or  8 ) has been replaced faultlessly is stored in the suction status storing means  46  (S 211 ). 
     When the cartridge replacement is not carried out (S 207 ), the type of ink cartridge to be replaced and the fact that suction from the ink cartridge is being deferred are stored into the suction status storing means  46  (S 212 ). 
     In the above-mentioned embodiment, the cartridge replacing position is defined by the window  6  and the partitioning portion  2   c  of the case body. In a printer having a window  6 ′ through which the ink cartridges  7  and  8  are both exposed, as shown in FIG.  18 ( a ), the cartridge replacing position may be specified by marking a proper position with a cartridge replacing position CP. In a printer shown in FIG.  18 ( b ), windows  61  and  62  are respectively provided for specifying the cartridge replacing positions of the black ink cartridge and the color ink cartridge. A printer shown in FIG.  18 ( c ) is provided with ink cartridges  81 ,  82  and  83  of different colors. In this printer, windows  62 ,  63  and  64  are provided at positions confronted with the color ink cartridges, respectively. In those printers, the kinds of ink cartridges can be clearly indicated by the utilization of a broad area of the case body. Therefore, there is no chance that the user erroneously selects the ink cartridge.