Patent Abstract:
An object of this invention is to provide an ink jet printing apparatus that can detect a state causing a printing operation failure without adding a sensor and also enhance the ease of handling on the part of the user while keeping an apparatus cost from rising. For this purpose, in a serial type ink jet printing apparatus, a travel range in which the print head  303  can be moved is detected and it is decided whether the detected travel range is a proper travel range. When, for example, the travel range is determined to be, it is decided that there is an obstacle in a path of the print head and a decision result is displayed. When the travel range is determined to be, it is decided that the ink tank is not properly mounted on the print head and the corresponding indication is made.

Full Description:
[0001]    This application claims priority from Japanese Patent Application No. 2003-050122 filed Feb. 26, 2003, which is incorporated hereinto by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to an ink jet printing apparatus of a so-called serial type which performs a printing operation by moving a print head in a main scan direction and also moving a print medium in a subscan direction crossing the main scan direction, and more particularly to an ink jet printing apparatus capable of easily detecting the condition of use of the printing apparatus and a method of controlling the same.  
           [0004]    2. Description of the Related Art  
           [0005]    A common serial type ink jet printing apparatus mounts one or more print heads on a carriage that moves in the main scan direction and also removably mounts on the print heads ink tanks accommodating inks to be supplied to the respective print heads. In the ink jet printing apparatus with the ink tanks removably mounted on the print heads, when the ink tanks run out of inks, the inks can be replenished by replacing the old tanks with new tanks filled with inks, facilitating their handling on the part of user.  
           [0006]    One conventionally known construction for removably mounting ink tanks on print heads engages a part of each ink tank in a groove formed in the associated print head. In this construction, fitting a part of each ink tank in the groove formed in the associated print head can bring a liquid supply port formed at a bottom of each ink tank into hermetic engagement with an ink receiving port that communicates with a common liquid chamber of the print head. In this type of ink jet printing apparatus, the ink tanks must engage the corresponding print heads properly for supply of ink from the ink tanks to the print heads.  
           [0007]    To meet this requirement, conventional ink jet printing apparatus employ a detection means, such as a sensor or switch, to determine whether or not the ink tanks are properly mounted to a mounting portion of the associated print head in order to alert the user when any tank is not properly mounted.  
           [0008]    However, such a switch or sensor detects only the mounted state of ink tanks and does not detect any other conditions. Thus, from the standpoint of cost performance, such a detection means is not normally used in relatively inexpensive apparatus. In conventional apparatus therefore, any improper mounting of an ink tank at the start of the use of the apparatus or during an ink tank replacement results in ink failing to be supplied to the associated print head, which in turn causes an ink ejection failure of the print head.  
           [0009]    In the serial type ink jet printing apparatus., a trouble may occur in which an obstacle present in a carriage path blocks a proper movement of the carriage.  
           [0010]    For example, the user may inadvertently start using a printing apparatus without removing a protective material inserted in the apparatus for its protection during shipping. If power is initially turned on with the protective material (obstacle) left in the carriage path, a reference position of a print head is determined at a wrong position, which prevents the print head position from being recognized correctly in subsequent printing operations. In that case, a print medium fails to be fed at a correct timing with respect to the reciprocal movement of the print head, making it impossible to produce a desired printing operation.  
           [0011]    To reliably prevent such a trouble, it is necessary to check for any obstacle present in the carriage path by using a sensor. This sensor, however, is not normally used in inexpensive printing apparatus and the resolving of this problem is entirely left to the user&#39;s careful handling during unpacking.  
         SUMMARY OF THE INVENTION  
         [0012]    For solving the above-mentioned problem, it is an object of this invention to provide an ink jet printing apparatus which can detect a state of ink tanks mounted on the print head and a presence or absence of an obstacle in the path of the print head without adding a sensor and which also can enhance the ease of handling on the part of the user while keeping an apparatus cost from rising. It is also an object of this invention to provide a method of controlling such an ink jet printing apparatus.  
           [0013]    To achieve the above objective, the present invention provides an ink jet printing apparatus which performs printing by moving a print head in a main scan direction and also feeding a print medium in a subscan direction crossing the main scan direction, the ink jet printing apparatus comprising: a detection means for detecting a travel range of the print head; a decision means for determining whether or not the detected travel range is a proper travel range; and a control means for performing a predetermined control if the decision means decides that the travel range of the print head is not the proper travel range.  
           [0014]    In this invention, the detection means detects a range in which the print head can be moved and determines whether or not the detected travel range is a proper travel range, thereby determining whether an obstacle such as a protective packing material exists in a travel path of the print head. If there is an unwanted object such as a protective packing material in the path of the print head, the print head motion is interfered with by the obstacle. As a result, the travel range of the print head, as detected by the detection means, is shorter than a print head movable range that is available when there is no obstacle. The decision means therefore decides that the print head travel range is not a proper one and, based on this decision, the control means performs controls, such as displaying a predetermined indication and stopping a print head drive motor, to prevent a printing operation from being executed under an improper condition.  
           [0015]    As described above, since this invention detects a movable range of the print head and checks if the detected movable range is an appropriate one, it is possible to detect undesired states that will result in operation failures, such as improperly mounted ink tanks on the print head and an obstacle lying in the path of the print head, without having to add a sensor. This in turn greatly facilitates the ease of use while keeping the apparatus cost from increasing.  
           [0016]    The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1A is a schematic perspective view of an ink jet printing apparatus in a first embodiment of the present invention;  
         [0018]    [0018]FIG. 1B is an enlarged view of an operation/display unit of FIG. 1A;  
         [0019]    [0019]FIG. 2 is a perspective view schematically showing an inner construction of an ink jet printing apparatus body of this invention;  
         [0020]    [0020]FIG. 3A is a perspective view showing how print heads and ink tanks are mounted on the ink jet printing apparatus of FIG. 1A, with a front cover open;  
         [0021]    [0021]FIG. 3B is a perspective view showing how print heads are mounted on a carriage in the state of FIG. 3A;  
         [0022]    [0022]FIG. 3C is a perspective view showing how ink tanks are mounted on the print heads in the state of FIG. 3B;  
         [0023]    [0023]FIG. 4A is a perspective view showing the ink tanks improperly mounted on the print heads;  
         [0024]    [0024]FIG. 4B is a perspective view showing a position where the improperly mounted ink tanks abut an enclosure of the printing apparatus when the carriage is moved;  
         [0025]    [0025]FIG. 5 is a perspective view showing an obstacle, such as a protection material for transport, in the carriage path in the ink jet printing apparatus body;  
         [0026]    [0026]FIG. 6 is a block diagram showing an outline configuration of a control system for the ink jet printing apparatus;  
         [0027]    FIGS.  7 A- 7 D are explanatory plan views showing how to determine whether an obstacle exists in a print head path and whether ink tanks are correctly mounted;  
         [0028]    [0028]FIG. 8 is a flow chart showing a sequence of operations executed when a power is turned on in a first embodiment of the invention;  
         [0029]    [0029]FIG. 9 is a flow chart showing a sequence of operations executed when a front cover is closed in the first embodiment of the invention; and  
         [0030]    FIGS.  10 A- 10 D are explanatory plan views showing how a kind of an improperly mounted ink tank is identified in a second embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0031]    Now, embodiments of the present invention will be described.  
         [0032]    (First Embodiment)  
         [0033]    [0033]FIG. 1A is an external perspective view of an ink jet printing apparatus in a first embodiment of this invention; and FIG. 1B is an enlarged view showing an operation/display unit of FIG. 1A.  
         [0034]    In FIG. 1A, reference number  10  denotes a serial type ink jet printing apparatus and  100  represents a body of the apparatus. The apparatus body  100  has an internal construction of FIG. 2 and also has mounted at its front a front cover  101  that can be opened and closed. On a top surface of the front cover  101  is mounted an operation/display unit  106 , which, as shown in FIG. 1B, has switches  107   a ,  107   b  for turning the apparatus power on or off and setting a variety of printing modes and a display  108  for indicating a state of the printing apparatus. Opening the front cover  101  can expose the interior of the apparatus body  100  as shown in FIG. 3A, allowing the print head and ink tank to be accessed for replacement.  
         [0035]    [0035]FIG. 2 is a perspective view schematically showing an inner construction of the apparatus body  100 .  
         [0036]    In the figure, denoted  206  is a transport roller  206  which transports to a printable area a print medium P that was fed by an automatic paper feeder  102  to a paper feed position. The print medium P transported to the printable area by the transport roller  206  is now supported on a platen  205 .  
         [0037]    Designated  201  is a carriage  201  movably supported on two parallel guide shafts  202 ,  203  installed in the apparatus body  100 . On this carriage  201  is removably mounted a print head  303 , on which an ink tank  204  is also removably mounted.  
         [0038]    The carriage  201  is driven by a DC motor not shown to reciprocally move (main-scan) over a scan area including a print area in a main scan direction indicated by arrows Q 1 , Q 2  (axial direction of the guide shafts  202 ,  203 ), during which time the print head  303  mounted on the carriage  201  ejects ink from its nozzles onto the print medium P situated immediately below to perform printing for one scan.  
         [0039]    With one main scan completed, the print medium P is fed a predetermined distance in a subscan direction indicated by an arrow R and waits for the next scan. These main scan and subscan are alternately repeated until one page of printing is completed.  
         [0040]    Now, referring to FIG. 3, a construction and a procedure for mounting and removing the print head  303  and the ink tank  204  will be explained.  
         [0041]    The print head  303  and the ink tank  204  are replaced by opening the front cover  301  provided on the front side of the apparatus body  100  as shown in FIG. 3A to expose the carriage  201  supported inside the apparatus body  100 . The print head  303  is mounted on the carriage  201  by engaging the print head  303  in a container-like holder  201   a  formed on the carriage  201 . In this embodiment, the print head  303  has four head portions for yellow (Y), cyan (C), magenta (M) and black (Bk) ink. These head portions, when mounted on the carriage  201 , are electrically connected to a flexible printed circuit board and receive signals to eject ink.  
         [0042]    The print head  303  has a plurality of ink tank accommodation portions (in this case, two)  303   a ,  303   b , which can accommodate two independent ink tanks  204   a ,  204   b . Of the two ink tanks  204   a ,  204   b , the ink tank  204   b  is a black ink tank, a single container holding a black ink therein. The other ink tank  204   a  is a color ink tank, the interior of which is divided into three ink containers for holding Y, M and C inks respectively. Bottom portions of these ink tanks  204   a ,  204   b  are formed with ink supply ports for the associated ink containers (not shown). When these ink tanks  204   a ,  204   b  are properly mounted on the carriage  201 , the ink supply ports of the individual ink containers communicate with ink receiving ports of the respective head portions of the print head  303 , supplying inks from the ink containers to the print head  303 .  
         [0043]    [0043]FIG. 4A shows the ink tanks  204   a ,  204   b  mounted on the print head  303 . One of the ink tanks (color ink tank) 204   a  is correctly mounted on the print head  303  whereas the other ink tank (black ink tank) 204   b  is not yet fully mounted. When the ink tank  204   a  is correctly mounted on the print head  303 , a back portion of the ink tank  204   a  is held almost vertically along a back of the print head  303  so that a front face of the ink tank  204   a  rests behind a front of sidewall portions  303   a  of the print head  303 . In this state the ink tank  204   a  has its engagement projection  204   a  l fit in an engagement recess  303   b  formed in a top surface of the print head  303  and is thus firmly held without a play. When the properly mounted ink tank  204   a  is to be removed from the print head  303 , an upper part of the ink tank  204   a  is pulled forward to disengage the engagement projection  204   a   1  from the engagement recess  303   b.    
         [0044]    In a state where the ink tank  204   b  is not yet fully mounted (before being mounted correctly), the ink tank  204   b  protrudes forwardly from the front of the sidewall portions  303   a  of the print head  303 , with its engagement projection  204   b   1  disengaged from the engagement recess  303   b . In this state, pushing the ink tank  204   b  rearward can bring it into the same properly mounted state as the ink tank  204   a.    
         [0045]    When the ink tank  204   b  is not in the fully mounted state, moving the carriage  201  in the backward direction (Q 2  direction) causes an ink tank wall surface  204   b   2  to interfere with one end portion  403   a  (see FIG. 4B) of a housing  403  enclosing the apparatus body  100 , thereby preventing a further movement of the carriage in the backward direction (Q 2  direction). When the carriage  201  is moved in the forward direction (Q 1  direction), the other ink tank wall surface  204   b   2  of the ink tank  204   b  interferes with the other end portion  403   b  (see FIG. 3A) of the housing  403  enclosing the apparatus body  100 , preventing a further movement of the carriage in the forward direction (Q 1  direction). When both of the ink tanks  204   a ,  204   b  are in the properly mounted state, the carriage  201  can move in the forward and backward directions beyond a movable range or travel range that is available when one of the ink tanks is not fully mounted. The carriage travel range is maximum when both of the ink tanks are correctly mounted. This is one of the features of this embodiment of the invention.  
         [0046]    When the ink tanks are not in the fully mounted state, as described above, the current position and the movable range of the carriage  201  can be determined by a carriage position detection sensor and a CPU in the control system described later. The carriage position detection sensor may use a conventionally available sensor, for example, a well-known linear encoder (not shown) having a scale arranged.narallel to the guide shafts  202 ,  203 . Even if the ink tanks  204   a ,  204   b  are properly mounted on the print head  303 , when there is an obstacle in the paths of the carriage  201  and the print head  303 , the travel range of the carriage  201  becomes shorter than the maximum movable range. The travel range of the carriage  201  and the travel range of the print head  303  mounted on the carriage  201  are the same, so in this specification no distinction is made between them.  
         [0047]    [0047]FIG. 5 shows an obstacle  507  present in the path of the carriege  201 . This obstacle  507  may, for example, be a protective packing material filled in the path of the movable carriage  201  to protect the inner structure of the ink jet printing apparatus  10  during transport. The protective material  507  needs to be removed after the delivered ink jet printing apparatus  10  is unpacked and before it is used. Normally, this protective material  507  is not easily recognized as it is installed at the end of the path of the carriage  201 , and thus the user often starts using the printing apparatus without removing the protective material.  
         [0048]    Should the carriage  201  be driven with such a protective material  507  left in its path, the carriage  201  or the print head  303  interferes with the obstacle  507  and its movable range is limited to a shorter range than when the obstacle  507  is not present. The movable range of the carriage  201  is similarly reduced also when other obstacles than the protective material  507  exist in the paths of the carriage  201  and print head  303 .  
         [0049]    [0049]FIG. 6 is a block diagram showing an outline configuration of a control system of the ink jet printing apparatus in the first embodiment.  
         [0050]    Print data and control data, such as characters and images to be printed in the ink jet printing apparatus lo, are sent from an external device  650  such as a host computer to a receive buffer  601  of the apparatus body  100  where they are stored. Data for checking if what the external device  650  has transmitted is being correctly received by the apparatus body  100  and data indicating the operating state of the apparatus body  100  are returned from the ink jet printing apparatus  10  to the external device  650 .  
         [0051]    The data stored in the receive buffer  601  is processed into data, which is to be printed when the print head  303  performs main scans, under the control of a CPU  602  (control and decision means) that executes calculations, decisions and controls according to programs stored in a ROM  611 . The processed data is temporarily stored in a print buffer in a random access memory (RAM)  603  and then transferred to a print head control unit  610 , which in turn controls a print head unit  612  of the print head  303  to print data such as characters and images. The print head control unit  610  also reads temperature information representing the state of the print head unit  612  and sends it to the CPU  602  which in turn sends the corresponding control data to the print head control unit  610  to control the ink ejection operation of the print head  303 .  
         [0052]    A mechanical control unit  604 , according to a command from the CPU  602 , controls the driving of a mechanical unit  605  including a carriage drive motor and a line feed motor.  
         [0053]    A sensor/SW control unit  606  sends signals from a sensor/SW unit  607  made up of various sensors and switches to the CPU  602 . The sensor/SW unit  607  includes a carriage position detection sensor such as a linear encoder for detecting the position of the carriage  201 . A display device control unit  608 , according to commands from the CPU  602 , controls a display unit  609  made up of LEDs and a liquid crystal display in the operation/display unit  106 .  
         [0054]    Next, referring to FIGS.  7 A- 7 D, FIG. 8 and FIG. 9, a method of checking a mounting state of the ink tanks  204  and a presence or absence of an obstacle in the path of the carriage. FIG. 7 is an explanatory plan view showing a positional relation between parts in the carriage path. FIG. 8 and FIG. 9 are flow charts showing detection sequences to check for an improper. mounting of ink tanks and a presence or absence of an obstacle in the carriage path, FIG. 8 representing processing to be executed when a power is turned on and FIG. 9 representing processing to be executed when the front cover is closed.  
         [0055]    In the first embodiment, the above detection operation is performed at two timings when a power is turned on and when the front cover is closed.  
         [0056]    First, processing to be executed at a turn-on-of power will be explained below.  
         [0057]    When a power switch of the ink jet printing apparatus  10  is turned on, power-ON processing shown in steps S 801 -S 808  of FIG. 8 is executed. That is, immediately after the power is turned on, an absolute position of the carriage  201  is not known. Thus, the carriage  201  is moved in a direction Q 2  (backward direction) toward a reference position (shown at  a  in FIGS.  7 A- 7 D) and a position at which the carriage engages, and is stopped by, some member is temporarily taken as a preliminary reference position (step S 801 ). Next, the carriage  201  is moved in a direction Q 1  (forward direction) toward a maximum movable position (shown at  b  in FIGS.  7 A- 7 D) at the other end of the path on a (non-reference) side opposite the reference position  a . When the carriage engages some member and is stopped by it, a distance from this position to the preliminary reference position is determined (step S 802 ). This is done by the CPU  602  counting the number of pulses received from the carriage position detection means. Then, it is checked whether the travel range or the distance traveled agrees with the preset maximum movable range (step S 803 ). If the distance traveled is shorter than the maximum movable range, the processing moves to step S 805  where it stops the carriage drive motor in the mechanical unit  605  through the mechanical control unit  604  (step S 805 ). If the distance traveled agrees with the maximum movable range, the processing moves to step S 804  to continue the predetermined power-ON processing.  
         [0058]    That is, when the ink tanks  204  are not fully engaged, the ink tanks  204  interfere with the end portions  403   a ,  403   b  of the housing  403  during the reciprocal movement as shown in FIG. 7C and FIG. 7D. As a result, the travel range L 1  is shorter than the preset maximum movable range L 0  (see FIG. 7B). Further, when a protective packing material  507  is left inserted in the path of the carriage  201 , the carriage  201  interferes with the packing protective material  706  (see FIG. 7A) and therefore its travel range L 2  becomes shorter than the preset maximum movable range L 0 . If the travel range or the distance traveled determined by step S 802  differs from the maximum movable range L 0 , it is decided that an error has occurred and the carriage drive motor is quickly stopped.  
         [0059]    Then, based on the distance traveled L 1  or L 2 , it is determined whether the error in question is caused by an improper mounting of the ink tank (ink tank mounting error) or by a presence of an obstacle such as a protective packing material  507  (obstacle error) (step S 806 ) and the corresponding indication is shown on the display unit  609  (step S 807 ). Further, error information is sent to the external device  650  connected to the ink jet printing apparatus  10  (step S 808 ) for appropriate display on the external device  650 .  
         [0060]    Next, processing executed when the front cover  101  is closed will be explained.  
         [0061]    When the front cover  101  is closed, there are two possible states. On state is that the reference position of the carriage  201  is already correctly determined during the power-ON processing, and the other state is that the reference position have failed to be correctly determined during the power-ON processing (reference position is not yet determined). If the carriage position is not determined correctly immediately after the power is turned on, the absolute position of the carriage  201  is still unknown. Thus, if a check on a reference position of the printing apparatus (step S 901 ) finds that the reference position is not yet determined, the front cover closing processing executes the reference position determination processing to determine the reference position. As in the power-ON processing described above, the carriage  201  is moved in the backward direction Q 2  toward the reference position (indicated at  a  in FIGS.  7 A- 7 D) and a position at which the carriage is blocked and stopped by some member is taken temporarily as a preliminary reference position (step S 908 ). Next, the carriage  201  is moved in the forward direction Q 1  toward the maximum movable position (indicated at  b  in FIGS.  7 A- 7 D) at the other end of the path on a (non-reference) side opposite the reference position  a . When the carriage abuts against and is stopped by some member, a distance from this position to the preliminary reference position is determined (stop S 909 ). This is done by the CPU  602  counting the number of pulses received from the carriage position detection means. Then, it is checked whether the travel range or the distance traveled agrees with the preset maximum movable range (step S 910 ). If the distance traveled is shorter than the maximum movable range, the processing moves to step S 904  where it stops the carriage drive motor in the mechanical unit  605  through the mechanical control unit  604  (step S 904 ). If the distance traveled agrees with the maximum movable range, the processing moves to step S 911  to continue the predetermined front cover closing processing.  
         [0062]    If the reference position of the carriage  201  is already determined correctly by the power-ON processing, the carriage  201  is moved in the backward direction Q 2  from an ink replacement position (indicated at  c  in FIGS.  7 A- 7 D) toward the reference position (indicated at  a  in FIGS.  7 A- 7 D) (step S 902 ).  
         [0063]    At this time, if the ink tanks  204  are in a correctly inserted position, the carriage  201  reaches the reference position  a . In response to this, the predetermined processing (front cover closing processing) triggered by the closure of the front cover  101  is continued (step S 911 ). However, when the ink tank  204   b  is not fully inserted, the carriage  201  cannot reach the reference position  a  because of an interference between the ink tank  204   b  and the end portion  403   a  of the housing  403 . Hence, the carriage drive motor is quickly stopped (step S 904 ). At the same time it is decided from the position of the carriage  201  detected at time of error that the error is caused by an improper mounting of the ink tank (step S 905 ) and the corresponding indication is made on the operation/display unit  106  of the ink jet printing apparatus  10 . At the same time, error information is sent to the external device  650  connected to the ink jet printing apparatus  10  for appropriate display on the external device (step S 907 ). The error display is reset by power-OFF processing or cover opening processing.  
         [0064]    (Second Embodiment)  
         [0065]    Next, a second embodiment of this invention will be described by referring to FIG. 10.  
         [0066]    In the second embodiment, as shown in FIG. 10, a plurality (in this case, two) of ink tanks  304   a ,  304   b  fitted in the print head  303  have different widths in the main scan direction. In other respects, the construction of the second embodiment is similar to that of the first embodiment.  
         [0067]    Taking advantage of the differing widths of the ink tanks  304   a ,  304   b , the second embodiment makes it possible to identify which ink tank is in an improper mounting state. Let us consider a case where the width of the black ink tank  304   b  containing a black ink is set larger than that of the color ink tank  204   a  containing color inks. It is also assumed that only the color ink tank  304   a  is in an improper mounting state, as shown in FIG. 10B. The travel range of the carriage  201  is L 11  which is dictated by an interference between the color ink tank  304   a  and the end portions  403   a ,  403   b  of the housing  403 . This range is shorter than a travel range (maximum movable range) L 10  in which the carriage  201  can move when both of the ink tanks  304   a ,  304   b  are properly installed (see FIG. 10A). If only the black ink tank  304   b  is in an improper mounting state as shown in FIG. 10C, the travel range of the carriage  201  is L 12 , which is shorter than the range L 11  obtained when only the color ink tank  304   b  is in a proper mounting state. If both of the ink tanks  304   a ,  304   b  are in an improper mounting state as shown in FIG. 10D, the travel range of the carriage  201 , L 13 , is shorter than the travel range L 12 .  
         [0068]    Detecting the travel range of the carriage  201  and comparing it with the maximum movable range as described above can determine whether the ink tanks  204  are properly mounted or not. Further, by checking which of L 11 , L 12  and L 13  the travel range matches, it is possible to identify the improperly mounted ink tank and to indicate the check result on the display unit thereby providing the user with appropriate information.  
         [0069]    In the above embodiments, a housing provided on the printing apparatus body is used as a member for restricting the movement of the carriage when the ink tanks are not fully mounted. The restricting member is not limited to the housing and may be constructed of a member protruding from other parts of the printing apparatus body.  
         [0070]    Further, in the above embodiments, we have taken up an example case in which two ink tanks are installed on the print head. This invention is also applicable to cases where one ink tank or three or more ink tanks are mounted. For example, a print head configuration is available which has four color inks—cyan, magenta, yellow and. black—contained in independent ink tanks. In another configuration the print head has a total of six ink tanks, i.e., two ink tanks containing a light cyan ink and a light magenta ink in addition to the above four color inks. This invention is also applicable to these printing apparatus.  
         [0071]    The above embodiments use a so-called bubble jet (trade mark) system in which the print head incorporates electrothermal transducers as a means to generate an energy for ejecting ink from its nozzles. A thermal energy generated by the electrothermal transducers produces bubbles in ink which, as they expand, expel ink droplets from the nozzles.  
         [0072]    It is noted, however, that the present invention is not limited to a particular configuration of an ink ejection energy generation means in the print head but can also be applied to ink jet printing apparatus with print heads that use other ejection energy generation means than the electrothermal transducers, such as ones having piezoelectric devices.  
         [0073]    The present invention has been described in detail with respect to preferred embodiments, and it will now be apparent from the foregoing to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspect, and it is the intention, therefore, in the apparent claims to cover all such changes and modifications as fall within the true spirit of the invention.

Technology Classification (CPC): 1