Patent Publication Number: US-8113610-B2

Title: Fluid ejection device and mounting position determination method

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a fluid ejection device and a mounting position determination method. 
     2. Description of the Prior Art 
     In a typical known ink jet recording device, a sensor is arranged on a recording head, and detects an edge of a recording paper sheet on a platen when the recording head moves in a main scan direction with the sensor facing the platen. For example, Patent Document 1 discloses an ink jet recording device. The disclosed ink jet recording device includes a reflective-type photo-interrupter composed of a light emitter unit including a light-emitting diode and a light receiver including a photo-transistor. The photo-interrupter is arranged upstream of the recording head in a sub scan direction. Light emitted from the light emitter unit is received by the light receiver and an output voltage of the light receiver changes in response to the level of the received light. The ink jet recording device detects an edge of a recording sheet based on a difference between the light level of the light reflected from the recording sheet and the light level of the light reflected from the platen. [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2004-90316 
     SUMMARY OF THE INVENTION 
     Such an ink jet recording device is manufactured by pre-assembling components into an assembly, and then by assembling a plurality of assemblies into a finished ink jet recording device. An assembly error of each component and a assembly error of the device may be summed. Even if each component is pre-assembled within a permissible assembly error range (design basis range), a mounting position of an assembly, when assembled into the final device, may fall out of the design basis range. If an unintentional impact is applied to the device in the course of delivery or because of the aging of the device, the device may fall finally out of the design basis range even though the device was set within the design basis range. Since the device can still print in such a case, the user may not notice such an irregularity. The ink jet recording device disclosed in Patent Document 1 can determine whether a mounting position of the element member falls within the design basis range by installing a dedicated mechanism for detecting a mounting error. With such a dedicated mechanism introduced, the device becomes complicated in structure, enlarged in size, and expensive in cost. 
     It is an object of the present invention to provide a fluid ejection device and a mounting position determination method for determining without any dedicated mechanism whether a mounting position of a predetermined element member forming a device falls within a design basis range. 
     The present invention has adopted the following module to achieve the above object. 
     A fluid ejection device of the present invention includes: 
     an ejection module for ejecting a fluid; 
     an edge detection module for detecting an edge of a target based on a variation in an output voltage in response to the presence or absence of the target on a platen; 
     a carriage module for mounting the ejection module and the edge detection module and moving the ejection module and the edge detection module in the predetermined direction while causing the ejection module to eject the fluid onto the target; 
     a memory module for storing information regarding a design basis range of a mounting position of a predetermined element member provided within a detection coverage area of the edge detection module; and 
     a determination module for controlling the edge detection module and the carriage module to detect the edge of the element member when an instruction to measure the mounting position of the element member is issued and determining, based on the output voltage of the edge detection module and the information regarding the design basis range stored on the memory module, whether a mounting position of the element member falls within the design basis range. 
     When the instruction to measure the mounting position of the element member is issued in the fluid ejection device, the determination module controls the edge detection module and the carriage module to detect the edge of the element member. On the basis of the output voltage of the edge detection module and the information regarding the design basis range stored on the memory module, the determination module determines whether a mounting position of the element member falls within the design basis range. In response to the instruction to measure the element member, the edge detection module for detecting the edge of the target is used to determine whether the mounting position of the element member falls within the design basis range. The determination as to whether the mounting position of the predetermined element member forming the device falls within the design basis range is preformed without using any dedicated mechanism. The predetermined element members may include a wiper for removing a fluid remnant sticking to the ejection module, a cap closing the ejection module, a blotter blotting the fluid ejected and landed off the target, a flushing member ejecting an ink drop to prevent the fluid from solidifying at the ejection module, and a platen. 
     In the fluid ejection of the present invention, the memory module may store, as the information regarding the design basis range, information regarding the design basis range of the mounting position of the element member in the predetermined direction, and the determination module may measure the mounting position of the element member in the predetermined direction based on the output voltage of the edge detection module and an amount of movement of the carriage module, and determines, based on the measured mounting position and the design basis range stored on the memory module, whether the mounting position of the element member falls within the design basis range. With this arrangement, a position error of the element member in the predetermined direction is recognized. 
     In the fluid ejection device, the memory module may store, as the information regarding the design basis range, information regarding the design basis range of the mounting position of the element member in a direction substantially perpendicular to the predetermined direction, and the determination module may measure the mounting position of the element member in the direction substantially perpendicular to the predetermined direction based on the output voltage of the edge detection module and an amount of movement of the carriage module, and determine, based on the measured mounting position and the design basis range stored on the memory module, whether the mounting position of the element member falls within the design basis range. With this arrangement, a position error of the element member in the direction substantially perpendicular to the predetermined direction is recognized. The mounting position may be represented by an output voltage of the edge detection module. 
     The fluid ejection device may further include a notification module for notifying a user of the determination results of the determination module. 
     In the fluid ejection device, the determination module may determine whether mounting positions of a plurality of element members fall within the design basis ranges thereof, and determine that at least one of the mounting position of the carriage module and the mounting position of the edge detection module with respect to the carriage module is likely to fall out of the design basis range if all the determined members are shifted out of the design basis range. With this arrangement, whether at least one of the mounting position of the carriage module and the mounting position of the edge detection module with respect to the carriage module falls out of the design basis range is determined without using any dedicated mechanism. 
     The fluid ejection device may include a lifting module for moving the element member in a direction substantially perpendicular to the predetermined direction, and a fault determination module for outputting a command to the lifting module to move the element member in the direction substantially perpendicular to the predetermined direction and determining that the lifting module malfunctions if the output of the edge detection module remains unchanged subsequent to the output of the command. With this arrangement, whether any fault takes place in the lifting module is determined without using any dedicated mechanism. 
     A mounting position determination method of the present invention is a method of a fluid ejection device of the present invention including an ejection module for ejecting a fluid, an edge detection module for detecting an edge of a target based on a variation in an output voltage in response to the presence or absence of the target on a platen, and a carriage module for mounting the ejection module and the edge detection module and moving the ejection module and the edge detection module in the predetermined direction while causing the ejection module to eject the fluid onto the target, the mounting position determination method including steps of: 
     controlling the edge detection module and the carriage module to detect the edge of a predetermined element member provided within a detection coverage area of the edge detection module when an instruction to measure a mounting position of the predetermined element member is issued; and 
     determining, based on the output voltage of the edge detection module and information regarding a design basis range of a mounting position of the element member read from memory module, whether the mounting position of the element member falls within the design basis range. 
     In the mounting position determination method, the edge detection module and the carriage module are controlled to detect the edge of a predetermined element member provided within a detection coverage area of the edge detection module when an instruction to measure a mounting position of the predetermined element member is issue. It is determined whether the mounting position of the element member falls within the design basis member, based on the output voltage of the edge detection module and information regarding a design basis range of the mounting position of the element member read from memory module. With this arrangement, in response to the instruction to measure the element member, the edge detection module for detecting the edge of the target is used to determine whether the mounting position of the element member falls within the design basis range. The determination as to whether the mounting position of the predetermined element member forming the device falls within the design basis range is preformed without using any dedicated mechanism. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a general configuration of an ink-jet printer  10  in accordance with one embodiment of the present invention: 
         FIG. 2  illustrates reference information  73   a  stored on a read-only memory (ROM)  73 ; 
         FIG. 3  illustrates an arrangement of test element members and an output voltage from a PW detector  46 ; 
         FIG. 4  is a flowchart illustrating a mounting error determination routine; 
         FIG. 5  illustrates an image of determination results displayed on a liquid-crystal display  82 ; 
         FIG. 6  is a flowchart illustrating a process of determining whether a cap motor malfunctions or not; and 
         FIG. 7  illustrates an image of other determination results displayed on the liquid-crystal display  82 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The embodiments of the present invention are described below with reference to the drawings.  FIG. 1  illustrates a generation configuration of an ink-jet printer  10  in accordance with one embodiment of the present invention.  FIG. 2  illustrates reference information  73   a  stored on a read-only memory (ROM)  73 . 
     Referring to  FIG. 1 , the ink-jet printer  10  of the present embodiment includes a platen  44  serving as a support for a paper sheet S, a printer mechanism  21  printing by ejecting ink drops onto the paper sheet S that is carried over the platen  44  from the back to the front by a sheet conveyance roller  35 , a paper-width (PW) detector  46 , arranged on the left side of a print head  24 , for detecting left and right edges of the paper sheet S, a flushing member  42  arranged in the vicinity of the left end of the platen  44 , a capping unit  40  arranged in the vicinity of the right end of the platen  44 , a wiper unit  49  arranged between the platen  44  and the capping unit  40 , a discharge section  48  formed in parallel with the platen  44  in a main scan direction, an operation panel  80  for displaying a variety of information and receiving a variety of instructions from the user, and a controller  70  for controlling the overall the ink-jet printer  10 . 
     The platen  44  is arranged at a position that faces the print head  24  that moves along the main scan direction. The platen  44  supports the paper sheet S so that a predetermined gap is maintained between the paper sheet S and the print head  24 . 
     The printer mechanism  21  includes a drive motor  33  for driving the sheet conveyance roller  35 , a carriage  22  that is moved in a reciprocatory fashion in the main scan direction along a guide  28  by a carriage belt  32  and a carriage motor  34 , ink cartridges  26 , mounted on the carriage  22 , and containing separately inks of yellow (Y), magenta (M), cyan (C), and black (B), the print head  24  for pressurizing the inks supplied from the ink cartridges  26  by deforming piezoelectric elements, and a nozzle  23  for ejecting ink drops pressurized by the print head  24 . A linear encoder  25  for detecting a position of the carriage  22  is arranged on the back of the carriage  22 . The position of the carriage  22  is controlled using the linear encoder  25 . The print head  24  may be of a type that applies a voltage on a heating resistor element (such as a heater) to heat ink and pressurizes the ink by bubbles caused by heating. 
     The PW detector  46  is an optical sensor including a light emitting element (not shown) including a light-emitting diode (LED) for emitting light toward the paper sheet S and a light receiver (not shown) for receiving light reflected from the paper sheet S and outputting a voltage responsive to the light level of the received light. The PW detector  46 , arranged on the left side of the print head  24 , detects the left and right edges of the paper sheet S while being moved laterally in a reciprocatory fashion. Upon receiving a detection command signal from the controller  70 , the PW detector  46  moves laterally in a reciprocatory fashion. Along with the movement of the PW detector  46 , the light emitting element emits light to the paper sheet S and the light receiver receives the light reflected from the paper sheet S and sends an output voltage responsive to the light level of the received light to the controller  70 . The light receiver has characteristics that the higher the light level of the received light is received, the lower the output voltage becomes. Alternatively, the light receiver may have characteristics that the higher the light level of the received light is received, the higher the output voltage becomes. 
     The flushing member  42  is arranged at an area leftward out of a printable region of the platen  44  as illustrated in  FIG. 1 . The flushing member  42  performs a flushing operation. In the flushing operation, ink drops are ejected periodically or at a predetermined timing in a manner not dependent on print data to prevent ink from being dried and solidifying at the tip of the nozzle  23 . 
     The capping unit  40  is arranged on the rightward out of the printable region of the platen  44  as illustrated in  FIG. 1 . The capping unit  40  is a generally rectangular parallelepiped and includes a cap  40   a  having a top opening and lifted up and down by a cap motor (not shown). While the ink-jet printer  10  is not used, the capping unit  40  closes the print head  24  in order to prevent the print head  24  from being dried. The position right above the capping unit  40  is also referred to a home position. 
     The wiper unit  49  is arranged to the right of the printable region of the platen  44 . The wiper unit  49  includes a wiper member  49   a  made of an elastic material such as a synthetic rubber and supported by a plastic member. The wiper member  49   a  is raised and lowered by a wiper motor (not shown). The wiper unit  49  is used to remove remnant ink sticking to the nozzle  23  and the surrounding area thereof. To remove the remnant ink, the wiper member  49   a  is left at an upper position by the wiper motor (not shown). When the carriage  22  moves leftward in the main scan direction from the home position, the top end of the wiper member  49   a  wipes the underside of the print head  24  mounted on the carriage  22 . In this way, the remnant ink sticking to the nozzle  23  and the surrounding area thereof on the underside of the print head  24  is removed. 
     The discharge section  48  is an elongated area extending in the main scan direction in parallel with the platen  44  and includes a blotting member  48   a  (such as sponge) for blotting ink. The discharge section  48  is used to receive ink ejected off the edge of the paper sheet S, for example, when printing with no outline is performed. The discharge section  48  is shorter than the platen  44  in the main scan direction as shown in  FIG. 1 . 
     The operation panel  80  includes a liquid-crystal display  82  for displaying a variety of information in response to a display command signal from the controller  70  and an operation button group  84  for inputting a variety commands when the user presses each button. The operation button group  84  includes a test button  84   a  that is used to input to the ink-jet printer  10  a command to start measurement of a mounting position. 
     As illustrated in  FIG. 1 , the controller  70  is configured as a microprocessor centered on a central processing unit (CPU)  72 , and includes a read-only memory (ROM)  73  storing a variety of programs such as a print process routine, and a variety of data, a random-access memory (RAM)  74  storing temporarily data, a flash memory  75  allowing data to be written and deleted, an interface (I/F)  76  exchanging data with an external device, and input and output ports (not shown). The controller  70  receives an on-off signal from the test button  84   a , an output voltage from the PW detector  46 , a signal related to a position of the carriage  22  from the linear encoder  25 , etc. via input ports (not shown). The controller  70  further receives a print job from a user personal computer  90  via the interface  76 . The controller  70  in turn outputs control signals to the print head  24 , the drive motor  33 , the cap motor, and the wiper motor, a display command signal to the liquid-crystal display  82 , a detection command signal to the PW detector  46 , etc. via output ports (not shown). The controller  70  further outputs print status information to the user personal computer  90  via the interface  76 . 
     The ROM  73  stores the reference information  73   a  as illustrated in  FIG. 2 . The reference information  73   a  relates to the design basis range of the mounting position of a test element member such as the wiper member  49   a , the platen  44 , the blotting member  48   a , or the flushing member  42 . More specifically, the ROM  73  stores the order and threshold values of member names, the design basis range in the horizontal direction and the design basis range in the vertical direction. 
     The order of the element member names is an arrangement order of the test element members starting leftward from the home position.  FIG. 3  illustrates the arrangement order of the test element members and an output voltage of the PW detector  46 . Referring to  FIG. 3 , in the arrangement order, the wiper member  49   a  is first, the platen  44  is second, the blotting member  48   a  is third, and the flushing member  42  is fourth. As illustrated in  FIG. 3 , a voltage V 1  and a position HP represent the output voltage of the PW detector  46  with the carriage  22  at the home position, and the home position, respectively. Voltages V 2 -V 5  and positions P 1 -P 4  represent, respectively, the output voltages of the PW detector  46  when right edges of the wiper member  49   a , the platen  44 , the blotting member  48   a  and the flushing member  42  are detected, and the right edge positions of the right edges of the wiper member  49   a , the platen  44 , the blotting member  48   a  and the flushing member  42 . Referring to  FIG. 3 , the wiper member  49   a , the platen  44 , the blotting member  48   a  and the flushing member  42  are arranged within a detection coverage range of the PW detector  46 , i.e., from the home position HP to position EP representing an end position of the flushing member  42 . 
     The threshold value is empirically determined so that a variation in the output voltage of the PW detector  46  that moves leftward from the home position and passes by the right edge of each test element member is reliably detected. Referring to  FIG. 3 , the output voltage of the PW detector  46  greatly changes when the PW detector  46  passes by the right edge of each test element member. The voltage change is determined by the position of each test element member in a vertical direction and the quality of the material (reflectance) of each test element member. In accordance with the present embodiment, the change in the output voltage is monitored beforehand at the moment the PW detector  46  passes by each test element member in experiments. A value allowing the right edge of each test element member to be reliably detected and not mistaken for noise is set as a threshold value. More specifically, the output voltage of the PW detector  46  moving leftward from the home position is monitored. When the output voltage decreases and becomes equal to or lower than a threshold value Vref 1 , the right edge of the wiper member  49   a  is considered to be detected. When the output voltage decreases and becomes equal to or lower than a threshold value Vref 2 , the right edge of the platen  44  is considered to be detected. When the output voltage then increases and becomes equal to or higher than a threshold value Vref 3 , the right edge of the blotting member  48   a  is considered to be detected. When the output voltage then decreases and becomes equal to or lower than a threshold value Vref 4 , the right edge of the flushing member  42  is considered to be detected. 
     The design basis range in the horizontal direction (the main scan direction) is determined by setting with respect to a design position of the right edge of each test element member, a tolerance within which the device operates without any problem. The design basis range in the horizontal direction extends from a horizontal lower limit to a horizontal upper limit, and is set for each test element member as listed in  FIG. 2 . The design basis range in the vertical direction (up-down direction) is determined by setting with respect to a design position of the right edge of each test element member in the vertical direction, a tolerance within which the device operates without any problem. The design basis range in the horizontal direction extends from a vertical lower limit to a vertical upper limit, and is set for each test element member as listed in  FIG. 2 . The lower limit and the upper limit are coordinates with respect to the home position serving as the origin. 
     The operation of the ink-jet printer  10  of the present embodiment thus constructed is described below particularly from the standpoint of determining whether the mounting position of each test element member falls within the design basis range with the PW detector  46  and notifying the user of the determination results.  FIG. 4  is a flowchart of an mounting error determination routine. The routine is stored on the ROM  73 . When the user presses the test button  84   a , the CPU  72  in the controller  70  executes the routine. The timing of the pressing of the test button  84   a  by the user may be at the moment when the assembling of finished element members into the ink-jet printer  10  in the manufacturing process is completed. It is noted that the paper sheet S is not set on the ink-jet printer  10  when the test button  84   a  is pressed. 
     Once the routine starts, the CPU  72  drives the drive motor  33  to move the carriage  22  to the home position, and resets the position of the carriage  22  to zero (step S 100 ). The CPU  72  then sets a counter n representing the order of  FIG. 3  to the value 1 (step S 100 ), enters the output voltage of the PW detector  46  while moving the carriage  22  in the main scan direction (step S 120 ), and determines whether the right edge of a n-th test element member is detected or not (step S 130 ). More specifically, if the test element member is the wiper member  49   a  (i.e., n=1), the right edge of the wiper member  49   a  is considered to be detected when the output voltage deceases and becomes equal to or lower than the threshold value Vref 1 . If the test element member is the platen  44  (i.e., n=2), the right edge of the platen  44  is considered to be detected when the output voltage decreases and becomes equal to or lower than the threshold value Vref 2 . If the test element member is the blotting member  48   a  (i.e., n=3), the right edge of the blotting member  48   a  is considered to be detected when the output voltage increases and becomes equal to or higher than the threshold value Vref 3 . If the test element member is the flushing member  42  (i.e., n=4), the right edge of the flushing member  42  is considered to be detected when the output voltage decreases and becomes equal to or lower than the threshold value Vref 4 . If it is determined in step S 130  that the right edge of the n-th test element member has not been detected, processing returns to step S 120 . If the right edge of the n-th test element member is detected, the CPU  72  determines the horizontal position of the right edge of the n-th test element member in response to a signal from the linear encoder  25  (step S 140 ). The CPU  72  determines whether the horizontal position of the right edge of the n-th test element member is out of the horizontal design basis range (step S 150 ). As previously discussed with reference to  FIG. 2 , the horizontal design basis range is determined on a per test element member basis. If the answer to the determination in step S 150  is affirmative, the CPU  72  stores on the RAM  74  the indication that the horizontal position of the right edge of the n-th test element member is out of the horizontal design basis range (step S 160 ). 
     Subsequent to step S 160  or if the answer to the determination in step S 150  is non-affirmative, the CPU  72  determines the vertical position of the test element member based on the output voltage of the PW detector  46  observed when the right edge of the n-th test element member is detected (step S 170 ). In accordance with the present embodiment, the correlation between the right edge of each test element member in the vertical direction and the output voltage of the PW detector  46  is empirically determined beforehand, and the determined correlation is stored in the form of a map, a table, or a function on the ROM  73 . The vertical position of the n-th test element member is determined based on the output voltage of the PW detector  46  in accordance with the correlation. The CPU  72  then determines whether the vertical position of the n-th test element member falls out of the design basis range (step S 180 ). The vertical design basis range is determined on a per test element member basis as illustrated in  FIG. 2 . If the answer to the determination in step S 180  is affirmative, the CPU  72  stores on the RAM  74  an indication that the vertical position of the n-th test element member is out of the design basis range (step S 190 ). 
     Subsequent to step S 190  or if the answer to the determination in step S 180  is non-affirmative, the CPU  72  determines whether the counter n reaches a maximum value (4 in this case) (step S 200 ). If the counter n is yet to reach the maximum value, the CPU  72  increments the counter n by 1 (step S 210 ), and then returns to step S 120 . If the counter n has reached the maximum value, the CPU  72  determines whether all the test element members exceed the design basis range in substantially the same direction to substantially the same degree (step S 220 ). If the answer to the determination in step S 220  is affirmative, the CPU  72  stores on the RAM  74  an indication that the mounting positions of the PW detector  46  and the carriage  22  are likely to be in error (step S 230 ). This operation is performed because the affirmative answer to the determination in step S 220  can mean that the mounting positions of the PW detector  46  and the carriage  22  are in error with the remaining test elements mounted to within the design basis range. The affirmative answer to the determination in step S 220  can also mean that the test element members exceed the design basis range in substantially the same direction to substantially the same degree. Subsequent to step S 230  or if the answer to the determination in step S 220  is non-affirmative, the CPU  72  moves the carriage  22  back to the home position (step S 240 ). The CPU  72  displays the determination results on the liquid-crystal display  82  of the operation panel  80  (step S 250 ). The routine thus ends. 
       FIG. 5  illustrates an example of the determination results displayed on the liquid-crystal display  82  of the operation panel  80 . “Passed” means that the mounting position falls within the design basis range and “failed” means that the mounting position falls out of the design basis range. In the mounting error determination routine, the test element member having the horizontal position thereof stored on the RAM  74  as falling out of the design basis range is displayed as the main scan direction as “failed,” and the test element member having the vertical position thereof stored on the RAM  74  as falling out of the design basis range is displayed as the up-down direction as “failed.” The other test element members are determined as being “passed.” Referring to  FIG. 5 , the wiper member  49   a , the blotting member  48   a , and the flushing member  42  fall within the horizontal design basis range and the vertical design basis range. The platen  44  falls out of the horizontal design basis range but within the vertical design basis range. If the indication that the mounting positions of the PW detector  46  and the carriage  22  are likely to be in error is stored on the RAM  74 , the message to that effect is displayed on the bottom display column below the determination results. If such an indication is not stored on the RAM  74 , the indication that the mounting positions of the PW detector  46  and the carriage  22  are likely to be normal is displayed on the bottom display column below the determination results as illustrated in  FIG. 5 . The user can know the determination results of the mounting positions of the test element members and can thus know that it is necessary that a test element member falling out of the design basis range be re-mounted. Referring to  FIG. 5 , the platen  44  needs re-mounting. 
     Here, the relationship between the elements of the embodiments and those of this invention will be described. The print head  24  corresponds to the ejection module, the paper sheet S corresponds to the target, the PW detector  46  corresponds to the edge detection module, the carriage  22  corresponds to the carriage module, the reference information  73   a  corresponds to the information relating to the design basis range, the ROM  73  corresponds to the memory module, and the controller  70  corresponds to the determination module. The main scan direction corresponds to the predetermined direction, the up-down direction corresponds to the direction substantially perpendicular to the predetermined direction, the liquid-crystal display  82  corresponds to the notification module, and the cap motor and the wiper motor correspond to the lifting module. 
     When the test button  84   a  in the ink-jet printer  10  described above is pressed, the PW detector  46  for detecting the edge of the paper sheet S is used to determine whether the mounting position of a test element member falls within the design basis range. Whether the mounting position of the test element member falls within the design basis range is thus determined without using any dedicated mechanism. The controller  70  determines the position of the right edge of the test element member from the output voltage of the PW detector  46  and the position of the carriage  22  read by the linear encoder  25 , and then determines whether the position of the right edge is out of the horizontal design basis range. The controller  70  can thus recognize a positional error of the test element member in the main scan direction. The controller  70  further determines the vertical position from the output voltage of the PW detector  46  and thus determines whether the vertical position is out of the vertical design basis range. The controller  70  can thus recognize a positional error of the test element member in the up-down direction. The controller  70  displays the determination results on the liquid-crystal display  82 , thereby causing the user to recognize the error of the mounting position of the test element member. If all the test element members are out of the design basis range in substantially the same direction to substantially the same degree, the controller  70  displays on the liquid-crystal display  82  the indication that the mounting positions of the PW detector  46  and the carriage  22  are likely to be in an error. Whether the mounting positions of the PW detector  46  and the carriage  22  are likely to be in an error is determined without using any dedicated mechanism. 
     The present invention is not limited to the above-described embodiments, and various changes may be possible to the above-described embodiments without departing from the scope of the present invention. 
     In the above-described embodiments, for example, the element members of the ink-jet printer  10  within the detection coverage range of the PW detector  46  are determined as to whether the mounting positions thereof fall within the design basis range. The moving element members of the ink-jet printer  10  may be determined as to whether they operate normally or not. More specifically, a process of  FIG. 6  may be executed subsequent to step S 100  of the mounting error determination routine illustrated in  FIG. 4 .  FIG. 6  is a flowchart of the process of determining whether the cap motor of the capping unit  40  malfunctions or not. After step S 100 , the PW detector  46  remains over the capping unit  40 . A cap  40   a  of the capping unit  40  remains at the lower position thereof. Subsequent to step S 100 , the CPU  72  enters the output voltage of the PW detector  46  (step S 101 ), and then operates the cap motor of the capping unit  40  to lift up the cap  40   a  to the upper position thereof (step S 103 ). The CPU  72  detect the output voltage of the PW detector  46  again (step S 105 ). The CPU  72  then determines whether a change in the output voltage responsive to the startup of the cap motor is consistent with the movement of the cap  40   a  from the lower position to the upper position (step S 107 ). If it is determined in step S 107  that the change in the output voltage is consistent with the movement of the cap  40   a , processing proceeds to step S 110 . If it is determined in step S 107  that the change in the output voltage is not consistent with the movement of the cap  40   a,  the controller  70  stores an indication of an error of the capping unit  40  onto the RAM  74  (step S 109 ). Processing then proceeds to step S 110 . When the determination results are displayed in step S 250 , the indication of the error of the capping unit  40 , if stored on the RAM  74 , is also displayed together. One display example on the liquid-crystal display  82  is illustrated in  FIG. 7 . In this way, whether the cap motor malfunctions or not is determined without using any dedicated mechanism. Similarly, the wiper motor of the wiper unit  49  may be checked as to whether the wiper motor malfunctions or not. 
     In accordance with the above-described embodiments, the vertical position of the test element member is measured from the output voltage of the PW detector  46 , and the measured vertical position is compared with the vertical design basis range represented in coordinates to determine whether the vertical position of the test element member is out of the vertical design basis range. Alternatively, the output voltage of the PW detector  46  may be compared with the vertical design basis range represented in voltage to determine whether the vertical position of the test element member is out of the vertical design basis range. 
     In accordance with the above-described embodiments, the mounting position in the main scan direction and mounting position in the up-down direction are compared with the design basis range. Alternatively, the mounting position in one direction only may be compared with the design basis range. 
     In accordance with the above-described embodiments, the image of the determination results is displayed on the liquid-crystal display  82 . The determination results may be presented in the form of an audio output from a loudspeaker (not shown) in addition to or instead of displaying the image of the determination results on the liquid-crystal display  82 . 
     In accordance with the above-described embodiments, the indication that the horizontal position of the test element member is out of the design basis range is stored on the RAM  74  in step S 160  of the mounting error determination routine and the indication that the vertical position of the test element member is out of the design basis range is stored on the RAM  74  in step S 190  of the mounting error determination routine. In addition to or instead of these operations, a displacement direction and a displacement amount may be stored. The displacement direction and the displacement amount stored on the RAM  74  may be displayed with the test element member associated therewith when the determination results are displayed on the liquid-crystal display  82  in step S 250  of the mounting error determination routine. An adjustment mechanism for adjusting finely the position of each test element member both in the main scan direction and the up-down direction may be arranged. Subsequent to the end of the mounting error determination routine, the CPU  72  may control the adjusting mechanism to cancel the displacement amount. 
     In accordance with the above-described embodiments, the fluid ejection device is applied to the ink-jet printer  10 . The present invention may be applicable to any type of fluid ejection device that ejects a fluid different from ink, a liquid-like body with functional material particles dispersed therewithin, or a liquid-like body such as a gel. The present invention may be applicable to a fluid ejection device that ejects a solid body that can be ejected as a fluid-like body. The present invention may be applicable to a fluid ejection device that ejects a fluid into which a material such as an electrode material or a color material may be dissolved. Such a material may be used in the manufacturing of a liquid-crystal display, an electroluminescence (EL) display, a plane emission display, or a color filter. The present invention may be applicable to a fluid ejection device that ejects a liquid-like body into which such a material is dispersed. The present invention may be applicable to a fluid ejection device that is used as a precision pipet and ejects a fluid serving as a specimen. The present invention may also be applicable to a fluid ejection device that ejects a lubricant to a precision machine such as a watch or a camera, and a fluid ejection device that ejects onto a board a transparent resin liquid such as an ultraviolet curing resin for forming a miniature hemispherical lens (optical lens) for use as optical communication elements. The present invention is also applicable to a fluid ejection device that ejects an acid etchant or an alkaline etchant to etch a board. The present invention is also applicable to a fluid ejection device that ejects a gel or powder such as a toner. 
     The present specification contains the subject matter of Japanese Patent Application No. 2008-000093 filed in Japan on Jan. 4, 2008, the entire disclosed contents of the specification, drawings, and claims of which are incorporated herein by reference.