JP2010137579A - Liquid ejecting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a liquid ejecting apparatus capable of reducing the consumption amount of liquid and a computer system therefor. <P>SOLUTION: The liquid ejecting apparatus is equipped with a plurality of nozzles for ejecting liquid, a movable ejecting head and a conveying mechanism for conveying a medium in a pre-determined conveying direction. The liquid ejecting apparatus for ejecting liquid to media from the plurality of nozzles is detects the part positioned upstream side in the conveying direction among the media, and in accordance with the detection result, causes nozzles positioned upstream side in the conveying direction among the plurality of nozzles not to eject liquid from the nozzles. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid ejection apparatus and a computer system.

  A color ink jet printer which is a typical liquid ejecting apparatus is already well known. This color inkjet printer includes a print head as an example of an ink jet type ejection head that ejects ink as an example of liquid from nozzles, and ejects ink onto printing paper as an example of a medium to thereby print images and characters. Etc. are recorded.

  The print head is supported by the carriage with the nozzle surface on which the nozzles are formed facing the print paper, and moves (main scan) in the width direction of the print paper along the guide member. Ink is ejected in synchronization with.

  In recent years, color ink jet printers capable of so-called borderless printing, which performs printing on the entire surface of printing paper, are gaining popularity for the reason that an output result of the same image as a photograph can be obtained. By borderless printing, for example, it is possible to print by ejecting ink without margins on the four edges of the printing paper.

  By the way, when the printing paper feeding operation and the ink ejection operation are repeatedly executed for printing on the printing paper, a state in which a part of the nozzle surface does not face the printing paper immediately before the end of printing occurs. In such a state, if ink is ejected from a nozzle that does not face the printing paper, the ink is wasted.

  In particular, in the case of borderless printing, since printing is performed on the entire surface of the printing paper, it is easy to cause a situation in which ink is ejected from nozzles that do not face the printing paper in the above state. Get higher.

JP 2001-96874 A

  The present invention has been made in view of such problems, and an object of the present invention is to realize a liquid ejection apparatus and a computer system that reduce liquid consumption.

  The main present invention has a feed mechanism for feeding a medium in a predetermined feed direction, and a discharge head including a plurality of nozzles arranged along the feed direction for discharging a liquid, In a liquid ejection apparatus that ejects liquid from the nozzle to a medium, the liquid ejection apparatus includes: a sensor that detects the presence or absence of the medium; and a controller that controls ejection of the liquid from the nozzle. Based on the change in the electrical signal due to the fact that the portion located upstream in the feed direction is not detected, the portion located upstream in the feed direction of the medium is more than the nozzle located upstream in the feed direction. Determining whether or not the downstream side of the feed direction has been reached, and the portion of the medium located on the upstream side of the feed direction is more than the nozzle located on the most upstream side of the feed direction, If it is determined that the recording medium has reached the downstream side in the recording direction, the liquid is not discharged from the nozzles located on the upstream side in the feeding direction after the medium is fed in the feeding direction by a predetermined amount. This is a liquid ejecting apparatus.

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

  According to the present invention, it is possible to realize a liquid ejection apparatus and a computer system that reduce liquid consumption.

1 is a block diagram illustrating a configuration of a printing system as an example of the present invention. 2 is a schematic perspective view illustrating an example of a main configuration of the color inkjet printer 20. FIG. 4 is a schematic diagram for explaining an example of a reflective optical sensor 29. FIG. FIG. 2 is a diagram illustrating a configuration around a carriage 28 of an inkjet printer. 3 is an explanatory diagram schematically showing a configuration of a linear encoder 11 attached to a carriage 28. FIG. 4 is a timing chart showing waveforms of two output signals of the linear encoder 11 during normal rotation and reverse rotation of a CR motor. 2 is a block diagram illustrating an example of an electrical configuration of the color inkjet printer 20. FIG. 4 is an explanatory diagram showing a nozzle arrangement on the lower surface of the print head. FIG. It is a flowchart for demonstrating 1st embodiment. 3 is a diagram schematically illustrating the positional relationship between the nozzles of the print head and the printing paper P. FIG. It is explanatory drawing which showed the external appearance structure of the computer system. It is a block diagram which shows the structure of the computer system shown in FIG.

  At least the following will be made clear by the description of the present specification and the accompanying drawings.

A liquid ejecting apparatus comprising a plurality of nozzles for ejecting liquid and having a movable ejection head and a feeding mechanism for feeding a medium in a predetermined feeding direction, and ejecting the liquid from the nozzle to the medium And detecting a portion of the medium located upstream in the feed direction, and based on the detection result, the liquid is not discharged from the nozzles located upstream of the feed direction among the plurality of nozzles. A liquid discharge apparatus characterized by:
A portion of the medium located upstream in the feed direction is detected, and based on the detection result, liquid is not discharged from nozzles located upstream of the feed direction among the plurality of nozzles. As a result, the liquid consumption can be reduced.

Further, a portion of the medium positioned upstream in the feed direction is detected, and based on the detection result, a nozzle located on the most upstream side in the feed direction among the plurality of nozzles and the feed from the nozzle. It is possible to prevent the liquid from being discharged from the nozzles whose direction distance is within a predetermined distance.
In this way, it is possible to further reduce the liquid consumption.

In addition, after a portion of the medium located upstream in the feeding direction is detected, a procedure for feeding the medium in the feeding direction by the feeding mechanism, and a liquid is ejected onto the medium by moving the ejection head The procedure may be repeated a predetermined number of times to end the discharge of the liquid onto the medium.
In this way, it is possible to completely record dots on the medium.

In addition, the predetermined number of times is a plurality of times, and liquid is ejected onto the medium in accordance with an increase in the accumulated paper feed amount of the medium after the portion located on the upstream side in the feeding direction of the medium is detected. The predetermined distance in the procedure may be increased.
In this way, it is possible to increase the number of nozzles that do not eject liquid in accordance with the increase in the number of nozzles that do not face the medium, and therefore it is possible to further reduce the amount of liquid consumption.

Further, an amount obtained by subtracting a predetermined amount from the accumulated paper feed amount may be set as the predetermined distance.
In this way, it is possible to secure a margin in consideration of detection errors when detecting a portion of the medium located upstream in the feeding direction.

Further, the predetermined amount may be smaller as the detection accuracy for detecting a portion of the medium located upstream in the feeding direction is higher.
In this way, it is possible to determine a nozzle that does not eject liquid more effectively by adjusting the amount of margin according to the magnitude of detection accuracy.

Further, a portion of the medium that is located upstream in the feed direction is determined by determining whether an end located on the upstream side in the feed direction has passed a predetermined position in the feed direction. It is good also as detecting.
In this way, it is possible to more reliably detect the portion of the medium located upstream in the feeding direction.

A medium supporting unit for supporting the medium; a light emitting unit for emitting light toward the medium supporting unit; and a light receiving sensor for receiving the light emitted by the light emitting unit, By determining whether or not the medium is in the traveling direction of the light emitted from the light emitting means based on the output value of the light receiving sensor, the end located on the upstream side in the feeding direction among the ends of the medium However, it may be determined whether or not it has passed a predetermined position in the feed direction.
In this way, it is possible to more easily determine whether the end located on the upstream side in the feed direction among the ends of the medium has passed a predetermined position in the feed direction.

Further, the light receiving unit that emits the light from the light emitting unit toward the predetermined position in the feeding direction on the medium support unit and is different in a main scanning direction, and receives the emitted light. Based on the output value of the sensor, it may be determined whether or not the medium is in the traveling direction of the light.
In this way, even when the medium is tilted, it is possible to reliably detect the portion of the medium that is located upstream in the paper feed direction.

The moving member movable in the main scanning direction is provided with the light emitting means and the light receiving sensor, and moving the moving member in the main scanning direction while moving the predetermined direction in the feeding direction on the medium support unit. The light is emitted from the light emitting means toward a plurality of different positions in the main scanning direction, and the medium advances the light based on an output value of the light receiving sensor that has received the emitted light. It may be determined whether or not it is in the direction.
In this way, when light is emitted from the light emitting means toward a plurality of different positions in the main scanning direction, there is no need to change the light emitting direction for each position.

The moving member includes the ejection head, and moves the moving member in the main scanning direction toward the predetermined positions in the feeding direction and different positions in the main scanning direction. And determining whether the medium is in the light traveling direction based on an output value of the light receiving sensor that has emitted the light from the light emitting means and received the emitted light, and is provided in the ejection head. The liquid may be discharged from the nozzle to the medium.
If it does in this way, the movement mechanism of the said moving member, the said light emission means, and the said light reception sensor can be made shared.

The liquid may be discharged over the entire surface of the medium.
In such a case, a situation in which liquid is easily discharged from a nozzle that does not face the medium in a state where a part of the nozzle surface does not face the medium is likely to occur.

The liquid may be ink, and the liquid ejecting apparatus may be a printing apparatus that performs printing on a printing medium that is the medium by ejecting ink from the nozzle.
In such a case, it is possible to realize a printing apparatus that exhibits the effects described above.

A plurality of nozzles for discharging the liquid; a movable discharge head; and a feeding mechanism for feeding the medium in a predetermined feeding direction, from the nozzles for the entire surface of the medium. In a liquid ejection apparatus that ejects liquid, a portion of the medium that is located upstream in the feed direction is detected, and a nozzle that is located on the most upstream side in the feed direction among the plurality of nozzles based on the detection result And the nozzle in which the distance in the feed direction from the nozzle is within a predetermined distance, and the feed mechanism after the portion located on the upstream side in the feed direction of the medium is detected The procedure for feeding the medium in the feeding direction and the procedure for moving the ejection head and ejecting the liquid onto the medium are repeated a predetermined number of times to complete the ejection of the liquid onto the medium. The predetermined number of times is a plurality of times, and the liquid is ejected to the medium in accordance with an increase in the accumulated paper feed amount of the medium after the portion located on the upstream side in the feed direction of the medium is detected. The predetermined distance in the procedure is increased, and an amount obtained by subtracting a predetermined amount from the accumulated paper feed amount is set as the predetermined distance, and the predetermined amount is a detection accuracy for detecting a portion of the medium located upstream in the feed direction. Is smaller, and among the edges of the medium, it is determined whether an end located on the upstream side in the feed direction has passed a predetermined position in the feed direction. A medium support part for detecting a position and supporting the medium, a light emitting means for emitting light toward the medium support part, and a light receiving sensor for receiving the light emitted by the light emitting means When, And determining whether the medium is in the traveling direction of the light emitted from the light emitting means based on the output value of the light receiving sensor, thereby positioning the medium upstream of the end of the medium in the feeding direction. The light emitting means and the light receiving sensor are provided on a moving member that can move in the main scanning direction, and the moving member moves the discharge head to the discharge head. And moving the moving member in the main scanning direction from the light emitting means toward the predetermined position in the feeding direction on the medium support unit and to a plurality of different positions in the main scanning direction. Based on an output value of the light receiving sensor that emits the light and receives the emitted light, it is determined whether or not the medium is in the traveling direction of the light, and from the nozzle provided in the ejection head, the medium is determined. A liquid ejecting apparatus characterized by ejecting liquid to the body can also be realized.
Since the liquid ejection device thus realized has all the effects described above, the object of the present invention can be achieved most effectively.

A computer main body, a display device connectable to the computer main body, and a liquid discharge device connectable to the computer main body, comprising a plurality of nozzles for discharging liquid, a movable discharge head, and a medium A liquid discharge device that discharges liquid from the nozzle to the medium, and detects a portion of the medium located on the upstream side in the feed direction; Based on the detection result, it is possible to realize a computer system comprising a liquid ejection device that prevents liquid from being ejected from nozzles located upstream in the feed direction among the plurality of nozzles. is there.
The computer system realized in this way is a system superior to the conventional system as a whole system.

=== Example of Overall Configuration of Apparatus ===
FIG. 1 is a block diagram showing a configuration of a printing system as an example of the present invention. This printing system includes a computer 90 and a color inkjet printer 20 as an example of a liquid ejection device. The printing system including the color inkjet printer 20 and the computer 90 can also be called a “liquid ejecting apparatus” in a broad sense. Although not shown, from the computer 90, the color inkjet printer 20, a display device such as a CRT 21 or a liquid crystal display device, an input device such as a keyboard or a mouse, a drive device such as a flexible drive device or a CD-ROM drive device, or the like. A computer system has been built.

  In the computer 90, an application program 95 operates under a predetermined operating system. A video driver 91 and a printer driver 96 are incorporated in the operating system, and print data PD to be transferred to the color inkjet printer 20 is output from the application program 95 via these drivers. The application program 95 that performs image retouching or the like performs desired processing on the image to be processed, and displays an image on the CRT 21 via the video driver 91.

  When the application program 95 issues a print command, the printer driver 96 of the computer 90 receives the image data from the application program 95 and converts it into print data PD to be supplied to the color inkjet printer 20. The printer driver 96 includes a resolution conversion module 97, a color conversion module 98, a halftone module 99, a rasterizer 100, a user interface display module 101, a UI printer interface module 102, and a color conversion lookup table LUT. And are provided.

  The resolution conversion module 97 plays a role of converting the resolution of the color image data formed by the application program 95 into the print resolution. The image data thus converted in resolution is still image information composed of three color components of RGB. The color conversion module 98 converts RGB image data into multi-gradation data of a plurality of ink colors that can be used by the color inkjet printer 20 for each pixel while referring to the color conversion lookup table LUT.

  The color-converted multi-gradation data has, for example, 256 gradation values. The halftone module 99 performs so-called halftone processing to generate halftone image data. The halftone image data is rearranged in the order of data to be transferred to the color inkjet printer 20 by the rasterizer 100, and is output as final print data PD. The print data PD includes raster data indicating the dot formation state during each main scan and data indicating the sub-scan feed amount.

  The user interface display module 101 has a function of displaying various user interface windows related to printing, and a function of receiving user input in these windows.

  The UI printer interface module 102 has a function of interfacing between a user interface (UI) and a color inkjet printer. Interpret the command instructed by the user through the user interface and send various commands COM to the color inkjet printer, or conversely interpret the command COM received from the color inkjet printer and perform various displays on the user interface .

  The printer driver 96 realizes a function of transmitting / receiving various commands COM, a function of supplying print data PD to the color inkjet printer 20, and the like. A program for realizing the function of the printer driver 96 is supplied in a form recorded on a computer-readable recording medium. Such recording media include flexible disks, CD-ROMs, magneto-optical disks, IC cards, ROM cartridges, punch cards, printed matter on which codes such as bar codes are printed, computer internal storage devices (such as RAM and ROM). A variety of computer-readable media such as a memory) and an external storage device can be used. It is also possible to download such a computer program to the computer 90 via the Internet.

  FIG. 2 is a schematic perspective view illustrating an example of a main configuration of the color inkjet printer 20. The color inkjet printer 20 includes a paper stacker 22, a paper feed roller 24 driven by a step motor (not shown), a platen 26 as an example of a medium support unit for supporting a medium, and a carriage as an example of a moving member. 28, a carriage motor 30, a traction belt 32 driven by the carriage motor 30, and a guide rail 34 for the carriage 28. The carriage 28 is mounted with a print head 36 as an example of an ejection head having a large number of nozzles, and a reflective optical sensor 29 described in detail later.

  The printing paper P is taken up by the paper feed roller 24 from the paper stacker 22 and sent on the surface of the platen 26 in a paper feed direction (hereinafter also referred to as a sub-scanning direction) as an example of a predetermined feed direction. The carriage 28 is pulled by a pulling belt 32 driven by a carriage motor 30 and moves in the main scanning direction along the guide rail 34. The main scanning direction means two directions perpendicular to the sub-scanning direction as shown in the figure. The paper feeding roller 24 also performs a paper feeding operation for supplying the printing paper P to the color ink jet printer 20 and a paper discharging operation for discharging the printing paper P from the color ink jet printer 20.

=== Configuration Example of Reflective Optical Sensor ===
FIG. 3 is a schematic diagram for explaining an example of the reflective optical sensor 29. The reflective optical sensor 29 is attached to the carriage 28, and includes a light emitting unit 38 as an example of a light emitting unit including, for example, a light emitting diode, and a light receiving unit 40 as an example of a light receiving sensor including, for example, a phototransistor. . Light emitted from the light emitting unit 38, that is, incident light is reflected by the platen 26 when there is no printing paper P or the printing paper P in the traveling direction of the emitted light, and the reflected light is received by the light receiving unit 40. It is converted into an electrical signal. And the magnitude | size of an electrical signal is measured as an output value of the light receiving sensor according to the intensity of the received reflected light.

  In the above description, as shown in the drawing, the light emitting unit 38 and the light receiving unit 40 are integrated to form a device called the reflective optical sensor 29. However, like the light emitting device and the light receiving device, respectively. A separate device may be configured.

  In the above, in order to obtain the intensity of the received reflected light, the magnitude of the electric signal is measured after converting the reflected light into an electric signal. However, the present invention is not limited to this. It is only necessary to measure the output value of the light receiving sensor according to the intensity of the reflected light.

=== Example of configuration around carriage ===
Next, the configuration around the carriage will be described. FIG. 4 is a diagram showing a configuration around the carriage 28 of the inkjet printer.

  The ink jet printer shown in FIG. 4 includes a paper feed motor (hereinafter also referred to as a PF motor) 31 that feeds paper as an example of a feed mechanism, and a print head 36 that ejects ink as an example of liquid onto the print paper P. A carriage 28 that is fixed and driven in the main scanning direction, a carriage motor (hereinafter also referred to as a CR motor) 30 that drives the carriage 28, a linear encoder 11 that is fixed to the carriage 28, and slits at predetermined intervals. The formed linear encoder code plate 12, the rotary encoder 13 (not shown) for the PF motor 31, the platen 26 that supports the printing paper P, and the paper that is driven by the PF motor 31 to convey the printing paper P Driven by the feed roller 24, a pulley 25 attached to the rotating shaft of the CR motor 30, and the pulley 25. And a pull belt 32.

  Next, the linear encoder 11 and the rotary encoder 13 will be described. FIG. 5 is an explanatory diagram schematically showing the configuration of the linear encoder 11 attached to the carriage 28.

  The linear encoder 11 shown in FIG. 5 includes a light emitting diode 11a, a collimator lens 11b, and a detection processing unit 11c. The detection processing unit 11c includes a plurality of (for example, four) photodiodes 11d, a signal processing circuit 11e, and, for example, two comparators 11fA and 11fB.

  When the voltage VCC is applied to both ends of the light emitting diode 11a through a resistor, light is emitted from the light emitting diode 11a. This light is condensed into parallel light by the collimator lens 11 b and passes through the linear encoder code plate 12. The linear encoder code plate 12 is provided with slits at predetermined intervals (for example, 1/180 inch (1 inch = 2.54 cm)).

  The parallel light that has passed through the linear encoder code plate 12 passes through a fixed slit (not shown), enters each photodiode 11d, and is converted into an electrical signal. The electric signals output from the four photodiodes 11d are processed in the signal processing circuit 11e, the signals output from the signal processing circuit 11e are compared in the comparators 11fA and 11fB, and the comparison result is output as a pulse. The pulses ENC-A and ENC-B output from the comparators 11fA and 11fB are the outputs of the linear encoder 11.

  FIG. 6 is a timing chart showing waveforms of two output signals of the linear encoder 11 at the time of forward rotation and reverse rotation of the CR motor.

  As shown in FIGS. 6 (a) and 6 (b), the pulse ENC-A and the pulse ENC-B differ in phase by 90 degrees in both cases of CR motor forward rotation and reverse rotation. When the CR motor 30 is rotating forward, that is, when the carriage 28 is moving in the main scanning direction, the pulse ENC-A is 90 degrees from the pulse ENC-B, as shown in FIG. When the phase is advanced by the time and the CR motor 30 is reversely rotated, the phase of the pulse ENC-A is delayed by 90 degrees from the pulse ENC-B, as shown in FIG. One cycle T of the pulse ENC-A and the pulse ENC-B is equal to the time during which the carriage 28 moves through the slit interval of the linear encoder code plate 12.

  Then, the rising edge and the rising edge of each of the output pulses ENC-A and ENC-B of the linear encoder 11 are detected, the number of detected edges is counted, and the rotational position of the CR motor 30 is based on the counted value. Is calculated. This count is incremented by “+1” when one edge is detected when the CR motor 30 is rotating forward, and is “−1” when one edge is detected when the CR motor 30 is rotating in the reverse direction. Is added. The period of each of the pulses ENC-A and ENC-B is the time from when a slit passes through the linear encoder 11 until the next slit passes through the linear encoder 11 of the linear encoder code plate 12. The pulse ENC-A and the pulse ENC-B are different in phase by 90 degrees. For this reason, the count value “1” of the count corresponds to ¼ of the slit interval of the linear encoder code plate 12. Thus, if the count value is multiplied by ¼ of the slit interval, the movement amount of the CR motor 30 from the rotational position corresponding to the count value “0” can be obtained based on the multiplication value. At this time, the resolution of the linear encoder 11 is ¼ of the slit interval of the linear encoder code plate 12.

  On the other hand, the rotary encoder 13 for the PF motor 31 has the same configuration as the linear encoder 11 except that the rotary encoder code plate is a rotating disk that rotates in accordance with the rotation of the PF motor 31. Two output pulses ENC-A and ENC-B are output, and the movement amount of the PF motor 31 can be obtained based on these outputs.

=== Example of an electrical configuration of a color inkjet printer ===
FIG. 7 is a block diagram illustrating an example of an electrical configuration of the color inkjet printer 20. The color inkjet printer 20 includes a buffer memory 50 that receives a signal supplied from a computer 90, an image buffer 52 that stores print data, a system controller 54 that controls the overall operation of the color inkjet printer 20, and a main memory 56. And an EEPROM 58. The system controller 54 further includes a main scanning drive circuit 61 that drives the carriage motor 30, a sub-scanning drive circuit 62 that drives the paper feed motor 31, a head drive circuit 63 that drives the print head 36, and reflective optics. A reflection type optical sensor control circuit 65 that controls the light emitting unit 38 and the light receiving unit 40 of the sensor 29, the linear encoder 11 described above, and the rotary encoder 13 described above are connected. The reflection type optical sensor control circuit 65 includes an electric signal measurement unit 66 for measuring an electric signal converted from the reflected light received by the light receiving unit 40.

  The print data transferred from the computer 90 is temporarily stored in the buffer memory 50. In the color ink jet printer 20, the system controller 54 reads necessary information from the print data from the buffer memory 50, and based on this information, the system controller 54 sends it to the main scanning drive circuit 61, the sub-scanning drive circuit 62, the head drive circuit 63, and the like. Send a control signal to it.

  The image buffer 52 stores print data of a plurality of color components received by the buffer memory 50. The head drive circuit 63 reads the print data of each color component from the image buffer 52 in accordance with a control signal from the system controller 54 and drives the nozzle array of each color provided in the print head 36 in response to this.

=== Example of nozzle arrangement of print head, etc. ===
FIG. 8 is an explanatory diagram showing the nozzle arrangement on the lower surface of the print head 36. The print head 36 has a black nozzle row, a yellow nozzle row, a magenta nozzle row, and a cyan nozzle row arranged on a straight line along the sub-scanning direction. As shown in the figure, each nozzle row is provided in two rows. In this specification, each nozzle row is designated as a first black nozzle row, a second black nozzle row, a first yellow nozzle row, They are called a two yellow nozzle row, a first magenta nozzle row, a second magenta nozzle row, a first cyan nozzle row, and a second cyan nozzle row.

  The black nozzle row (indicated by white circles) has 360 nozzles # 1 to # 360. Among these nozzles, odd-numbered nozzles # 1, # 3,..., # 359 are in the first black nozzle row, and even-numbered nozzles # 2, # 4,. Belongs to the nozzle row. The nozzles # 1, # 3,..., # 359 in the first black nozzle row are arranged at a constant nozzle pitch k · D along the sub-scanning direction. Here, D is the dot pitch in the sub-scanning direction, and k is an integer. The dot pitch D in the sub-scanning direction is equal to the pitch of the main scanning line (raster line). Hereinafter, the integer k representing the nozzle pitch k · D is simply referred to as “nozzle pitch k”. In the example of FIG. 8, the nozzle pitch k is 4 dots. However, the nozzle pitch k can be set to an arbitrary integer.

  The nozzles # 2, # 4,..., # 360 in the second black nozzle row are also arranged at a constant nozzle pitch k · D (nozzle pitch k = 4) along the sub-scanning direction. However, as shown in the figure, the position of each nozzle in the sub-scanning direction is shifted from the position of each nozzle in the first black nozzle row in the sub-scanning direction. In the example of FIG. 8, the amount of deviation is ½ · k · D (k = 4).

  The same applies to the yellow nozzle row (indicated by white triangles), the magenta nozzle row (indicated by white squares), and the cyan nozzle row (indicated by white rhombuses). That is, each nozzle row has 360 nozzles # 1 to # 360, of which odd-numbered nozzles # 1, # 3,..., # 359 are in the first row, # 2, # 4, ..., # 360 belongs to the second column. The nozzle rows are arranged at a constant nozzle pitch k · D along the sub-scanning direction, and the positions of the nozzles in the second row in the sub-scanning direction are the same as those in the sub-scanning direction of the nozzles in the first row. Compared with the position, it is shifted by ½ · k · D (k = 4).

  That is, the nozzle group arranged in the print head 36 has a zigzag shape. During printing, while the print head 36 moves at a constant speed in the main scanning direction together with the carriage 28, ink droplets are ejected from each nozzle. Discharged. However, depending on the printing method, not all nozzles are always used, and only some nozzles may be used.

  The reflective optical sensor 29 described above is attached to the carriage 28 together with the print head 36. In the present embodiment, the position of the reflective optical sensor 29 in the sub-scanning direction is as shown in the figure. This coincides with the position of the nozzle # 360 in the sub-scanning direction.

=== First Embodiment ===
Next, the first embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a flowchart for explaining the first embodiment. FIG. 10 will be described later.

  First, the user instructs to perform printing in the application program 95 or the like (step S2). When the application program 95 that has received this instruction issues a print command, the printer driver 96 of the computer 90 receives image data from the application program 95, and receives the raster data and the sub data indicating the dot formation state during each main scan. The print data PD including data indicating the scanning feed amount is converted. Further, the printer driver 96 supplies the print data PD to the color inkjet printer 20 together with various commands COM. The color inkjet printer 20 receives these by the buffer memory 50 and then transmits them to the image buffer 52 or the system controller 54.

  Further, the user can instruct the user interface display module 101 to perform the size of the printing paper P or borderless printing. The instruction by the user is received by the user interface display module 101 and sent to the UI printer interface module 102. The UI printer interface module 102 interprets the instructed command and transmits a command COM to the color inkjet printer 20. The color inkjet printer 20 receives the command COM by the buffer memory 50 and then transmits it to the system controller 54.

  Based on the command transmitted to the system controller 54, the color inkjet printer 20 feeds the printing paper P by driving the paper feed motor 31 by the sub-scanning drive circuit 62 (step S4).

  Then, the system controller 54 moves the carriage 28 in the main scanning direction while feeding the printing paper P in the paper feeding direction, and discharges ink from the print head 36 provided in the carriage 28 to perform borderless printing ( Step S6, Step S8). The printing paper P is fed in the paper feeding direction by driving the paper feeding motor 31 by the sub-scanning driving circuit 62, and the carriage 28 is moved in the main scanning direction by the main scanning driving circuit 61. The ink is ejected from the print head 36 by being driven by driving the print head 36 by the head drive circuit 63.

  The color inkjet printer 20 continues to perform the operations of step S6 and step S8. For example, when the number of movements of the carriage 28 in the main scanning direction reaches a predetermined number (step S10), the next main scanning is performed. From the movement of the carriage 28 in the direction, the following operation is performed.

  The system controller 54 controls the reflective optical sensor 29 provided in the carriage 28 by the reflective optical sensor control circuit 65, and emits light from the light emitting unit 38 of the reflective optical sensor 29 toward the platen 26 (step). S12).

  The system controller 54 moves the carriage 28 in the main scanning direction to eject ink from the print head 36 provided on the carriage 28 to perform borderless printing, and at a predetermined position in the paper feeding direction on the platen 26. Whether the printing paper P is in the light traveling direction based on the output value of the light receiving unit 40 that emits light from the light emitting unit 38 toward a plurality of different positions in the main scanning direction. Whether or not is detected (step S14).

  Note that, as described above, in the present embodiment, the position of the reflective optical sensor 29 in the paper feed direction matches the position of the nozzle # 360 in the paper feed direction. Corresponds to the position of nozzle # 360 in the paper feed direction.

  In the present embodiment, it is always detected whether or not the printing paper P is in the light traveling direction while the carriage 28 is moving in the main scanning direction. That is, when the light emitted from the light emitting unit 38 blocks the edge of the printing paper P, the incident destination of the light emitted from the light emitting unit 38 changes from the platen 26 to the printing paper P, and thus the reflected light is received. The magnitude of the electrical signal that is the output value of the light receiving unit 40 of the reflective optical sensor 29 changes. Then, by measuring the magnitude of the electric signal by the electric signal measuring unit 66, it is detected that the edge of the printing paper P has passed the light.

  When the movement of the carriage 28 in step S14 is completed, it is determined based on the output value of the light receiving unit 40 whether or not the printing paper P has come in the light traveling direction during the movement of the carriage 28 in the main scanning direction ( Step S16). That is, of the ends of the printing paper P, an end located upstream in the paper feed direction (hereinafter, this end is also referred to as a lower end) is a predetermined position in the paper feed direction (in this embodiment, nozzle # 360). The position of the printing paper P located upstream in the paper feeding direction is detected by determining whether or not the paper has passed the paper feeding direction position).

  As a result of the determination in step S16, if the printing paper P has come in the light traveling direction, the printing paper P is fed in the paper feeding direction (step S18), and then the process returns to step S14, and the light traveling direction. Until the printing paper P no longer comes, the above-described operation from step S14 to step S18 is repeated.

  As a result of the determination in step S16, when the printing paper P does not come in the light traveling direction, the following operation is performed.

  This will be described in more detail with reference to FIG. FIG. 10 is a diagram schematically showing the positional relationship between the nozzles of the print head 36 and the printing paper P. FIG.

  In each of FIGS. 10A to 10C, the small rectangle shown on the left side represents the nozzle of the print head 36. The numbers in the rectangles are nozzle numbers and correspond to the nozzle numbers shown in FIG. In FIG. 10, only the black nozzle row is shown for easy understanding, and the first black nozzle row and the second black nozzle row shown in FIG. 8 are shown on the same straight line. . In FIG. 10, the circle shown on the right side of the nozzle # 360 represents the reflective optical sensor 29. As described above, the position of the reflective optical sensor 29 in the paper feeding direction matches the position of the nozzle # 360 in the paper feeding direction. Further, on the right side of the black nozzle row, a part (lower right end portion) of the printing paper P is represented.

  First, attention is focused on FIG. FIG. 10A repeats the operations from step S14 to step S18 described above, and the nozzles of the print head 36 and the printing paper when it is determined in step S16 that the printing paper P has not come in the light traveling direction. The positional relationship of P is represented. As is apparent from the drawing, the carriage 28 provided with the print head 36 and the reflective optical sensor 29 is reflected optically during movement in the main scanning direction (in this embodiment, the arrow direction from the left to the right in the figure). The printing paper P does not come in the traveling direction of the light emitted from the light emitting unit 38 of the sensor 29.

  As described above, when the printing paper P does not come in the light traveling direction as a result of determination in step S16, the printing paper P is fed in the paper feeding direction as shown in FIGS. 10 (a) and 10 (b). (Step S20). In the present embodiment, the printing paper P is fed by 25 · D (D is a dot pitch).

  Next, the carriage 28 is moved in the main scanning direction (in this embodiment, the arrow direction from the left to the right in FIG. 10B), and ink is ejected from the nozzles of the print head 36 provided in the carriage 28. Then, borderless printing is performed (step S24). In the printing, ink is not discharged from the nozzles located upstream of the plurality of nozzles of the print head 36 in the paper feed direction. In the present embodiment, ink is prevented from being ejected from the nozzle located on the most upstream side in the paper feed direction and the nozzle in which the distance in the paper feed direction from the nozzle is within a predetermined distance. FIG. 10B shows nozzles # 353 to # 360 indicated by rectangles drawn by dotted lines.

  As can be understood from the above, a procedure (step S22) for determining the nozzles from which ink is not ejected is required before ink is ejected from the nozzles of the print head 36 to perform borderless printing (step S24). It is. A specific method for determining the nozzle that does not eject ink will be described later.

  Next, as shown in FIGS. 10B and 10C, the printing paper P is further fed in the paper feeding direction (step S20). In this embodiment, the printing paper P is also fed by 25 · D (D is a dot pitch).

  Next, the carriage 28 is moved in the main scanning direction (in this embodiment, the arrow direction from the left to the right in FIG. 10B), and ink is ejected from the nozzles of the print head 36 provided in the carriage 28. Then, borderless printing is performed (step S24). In the printing as well, ink is not discharged from the nozzles located upstream in the paper feed direction among the plurality of nozzles of the print head 36. In the present embodiment, ink is prevented from being ejected from the nozzle located on the most upstream side in the paper feed direction and the nozzle in which the distance in the paper feed direction from the nozzle is within a predetermined distance. FIG. 10C shows nozzles # 340 to # 360 indicated by rectangles drawn by dotted lines. The nozzles that do not eject ink are determined before step S24 (step S22).

  After the above procedure, that is, the procedure from step S20 to step S24, is repeated a predetermined number of times (in FIG. 9, this number is N), printing on the printing paper P is completed (step S26). Then, the printing paper P is discharged by the paper feed motor 31 driven by the sub-scanning drive circuit 62 (Step S28). Note that the predetermined number N is determined by the necessity of recording dots on the printing paper P, so that the nozzle pitch k described above, whether or not a so-called overlap recording method is used, and if used, a dot group on the same main scanning line. It is determined based on the number of nozzles for recording.

  Note that a program for performing the above processing is stored in the EEPROM 58, and the program is executed by the system controller 54.

  As described in the background art section, ejecting ink from nozzles that do not face the printing paper in a state where part of the nozzle surface does not face the printing paper results in wasteful consumption of ink. In particular, in the case of borderless printing, since printing is performed on the entire surface of the printing paper, it is easy to cause a situation in which ink is ejected from nozzles that do not face the printing paper in the above state. Get higher.

  Therefore, a portion of the printing paper located upstream in the paper feed direction is detected, and based on the detection result, ink is prevented from being ejected from nozzles located upstream in the paper feed direction among the plurality of nozzles. As a result, the ink consumption can be reduced, and the above problem can be solved.

  In the above description, the reflection type optical sensor is used, but the present invention is not limited to this. For example, the light emitting unit and the light receiving unit may be arranged so as to face each other in a direction perpendicular to the main scanning direction and the sub scanning direction, and the light emitting unit and the light receiving unit sandwich the printing paper.

  In the above description, in step S10, after the movement of the carriage 28 in the main scanning direction reaches a predetermined number of times, it starts to detect that the edge of the printing paper has passed light. However, the present invention is not limited to this. It is not something. For example, the detection may be started from the first movement of the carriage 28 in the main scanning direction, or an ideal detection timing may be obtained by calculation or the like to minimize the number of detections.

  In the above description, in the loop from step S20 to step S26, the nozzle that does not eject ink is determined every time it passes step S22. However, in the first step S22, the first to Nth nozzles are determined. The nozzle may be determined.

=== Method for Determining No-jet Nozzle ===
As described above, the nozzles that do not eject ink are determined in step S22. Here, an example of the nozzle determination method will be described with reference to FIGS. 9 and 10.

  First, as already described in the above embodiment, the nozzles that do not eject ink are nozzles located on the most upstream side in the paper feed direction and nozzles having a distance in the paper feed direction from the nozzle within a predetermined distance. In other words, in the example of FIG. 10, the nozzle # 360 and the distance from the nozzle # 360 in the paper feeding direction are within a predetermined distance.

  Next, the predetermined distance will be described. The predetermined distance is set to be large in accordance with the increase in the cumulative paper feed amount of the print paper P after the portion located on the upstream side in the paper feed direction of the print paper P is detected. More specifically, the predetermined distance is an amount obtained by subtracting the predetermined amount from the accumulated paper feed amount of the print paper P after the portion of the print paper P located upstream in the paper feed direction is detected. The accumulated paper feed amount is an amount of 25 · D (D is a dot pitch) in the example of FIG. 10B, and an amount of (25 · D + 25 · D) in the example of FIG. 10C. .

  The predetermined amount is determined according to the detection accuracy for detecting a portion of the printing paper P located upstream in the paper feed direction. If the predetermined distance is simply the accumulated paper feed amount, there is no problem if the portion of the printing paper P located upstream in the paper feed direction can be accurately detected. In such a case, a situation may occur in which a nozzle that does not eject ink faces the printing paper P. In order to avoid such inconvenience and to secure a certain margin, the predetermined amount is set. Therefore, the predetermined amount becomes smaller as the detection accuracy for detecting the portion of the printing paper P located upstream in the paper feeding direction is higher. In the example of FIG. 10, the amount of 10 · D is set as the predetermined amount.

  When the above determination method is applied to the examples of FIGS. 10B and 10C, nozzles that do not eject ink are as follows.

  In the example of FIG. 10B, the cumulative paper feed amount is an amount for 25 · D, and the predetermined amount is an amount for 10 · D. Therefore, the predetermined distance is a distance of 15 · D. The nozzles to be obtained are nozzles # 360 and nozzles whose distance in the paper feed direction from the nozzle # 360 is within a predetermined distance, and nozzles # 353 to # 360 are the nozzles. Note that the distance of the nozzle # 353 from the nozzle # 360 in the paper feeding direction is a distance of 14 · D.

  In the example of FIG. 10C, the cumulative paper feed amount is an amount for 50 · D, and the predetermined amount is an amount for 10 · D. Therefore, the predetermined distance is a distance of 40 · D. The nozzles to be obtained are nozzles # 360 and nozzles whose distance in the paper feed direction from the nozzle # 360 is within a predetermined distance, and nozzles # 340 to # 360 are the nozzles. The distance of the nozzle # 340 in the paper feed direction from the nozzle # 360 is a distance of 40 · D.

  As already described, the procedure from step S20 to step S24 shown in FIG. 9 is repeated a predetermined number of times (in FIG. 9, this number is N). Therefore, step S22 is repeated N times. The above-described examples of determining nozzles that do not eject ink according to FIGS. 10B and 10C are examples of determining nozzles in the first and second steps S22, respectively. The determination of the nozzle in step S22 from the third time to the Nth time can also be performed by the same method.

=== Other Embodiments ===
As mentioned above, although the liquid discharge apparatus etc. which concern on this invention have been demonstrated based on one Embodiment, Embodiment mentioned above is for making an understanding of this invention easy, and limits this invention. is not. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes the equivalents thereof.

  Further, although the printing paper has been described as an example of the medium, a film, a cloth, a thin metal plate, or the like may be used as the medium.

  In the above-described embodiment, the printing apparatus has been described as an example of the liquid ejection apparatus. However, the present invention is not limited to this. For example, color filter manufacturing apparatus, dyeing apparatus, fine processing apparatus, semiconductor manufacturing apparatus, surface processing apparatus, three-dimensional modeling machine, liquid vaporizer, organic EL manufacturing apparatus (particularly polymer EL manufacturing apparatus), display manufacturing apparatus, film formation You may apply the same technique as this embodiment to an apparatus, a DNA chip manufacturing apparatus, etc. Even if the present technology is applied to such a field, since the liquid can be ejected toward the medium, the above-described effects can be maintained.

  In the above-described embodiment, a color inkjet printer has been described as an example of a printing apparatus. However, the present invention is not limited to this, and can be applied to, for example, a monochrome inkjet printer.

  In the above embodiment, ink has been described as an example of a liquid, but the present invention is not limited to this. For example, a liquid (including water) containing a metal material, an organic material (particularly a polymer material), a magnetic material, a conductive material, a wiring material, a film forming material, a processing solution, a gene solution, or the like may be discharged from a nozzle. .

Further, in the above-described embodiment, a portion located on the upstream side in the paper feeding direction is detected in the printing paper, and the nozzle located on the most upstream side in the paper feeding direction among the plurality of nozzles based on the detection result The ink is prevented from being ejected from the nozzle whose distance in the paper feed direction from the nozzle is within a predetermined distance, but the present invention is not limited to this. For example, among the nozzles located on the most upstream side in the paper feeding direction and the nozzles with the distance in the paper feeding direction from the nozzles within a predetermined distance, there may be some nozzles that eject ink.
However, the above embodiment is more preferable in that the ink consumption can be further reduced.

Further, in the above embodiment, after a portion of the printing paper located upstream in the paper feeding direction is detected, a procedure for feeding the printing paper in the paper feeding direction by the paper feeding motor, and the printing head is moved to move the printing paper. The printing procedure is repeated a predetermined number of times to finish printing on the printing paper. However, the present invention is not limited to this.
However, the above embodiment is more preferable in that dots can be recorded on the printing paper.

In the above embodiment, the predetermined number of times is a plurality of times, and according to an increase in the cumulative paper feed amount of the print paper after the portion of the print paper located upstream in the paper feed direction is detected. Although the predetermined distance in the procedure for printing on the printing paper is increased, the present invention is not limited to this. For example, the predetermined distance may be a constant distance regardless of the increase in the cumulative paper feed amount.
However, in this way, it is possible to increase the number of nozzles that do not eject ink according to the increase in the number of nozzles that do not face the printing paper, and thus it is possible to further reduce the ink consumption. The above embodiment is more desirable.

In the above embodiment, an amount obtained by subtracting a predetermined amount from the accumulated paper feed amount is set as the predetermined distance. However, the present invention is not limited to this. For example, the accumulated paper feed amount may be set as the predetermined distance.
However, the above embodiment is more preferable in that a margin can be secured in consideration of a detection error when detecting a portion of the printing paper located upstream in the paper feed direction.

In the above-described embodiment, the predetermined amount is smaller as the detection accuracy for detecting the portion of the printing paper located on the upstream side in the paper feeding direction is higher. However, the present invention is not limited to this. For example, a value irrelevant to the detection accuracy may be set for the predetermined amount.
However, the above embodiment is more preferable in that a nozzle that does not eject ink more effectively can be determined by adjusting the amount of margin according to the magnitude of detection accuracy.

Further, in the above-described embodiment, it is determined whether or not the end of the print paper located upstream in the paper feed direction has passed through a predetermined position in the paper feed direction, thereby determining the paper feed of the print paper. Although the portion located upstream in the direction is detected, the present invention is not limited to this.
However, the above embodiment is preferable in that it can more reliably detect the portion of the printing paper located upstream in the paper feed direction.

In the above embodiment, a platen for supporting the printing paper, a light emitting unit for emitting light toward the platen, and a light receiving unit for receiving the light emitted by the light emitting unit. And determining whether or not the printing paper is in the traveling direction of the light emitted from the light emitting unit based on the output value of the light receiving unit. However, it has been determined whether or not it has passed a predetermined position in the paper feed direction, but is not limited to this.
However, it is easier to determine whether the end located upstream of the paper feed direction among the edges of the print paper has passed a predetermined position in the paper feed direction. Is more desirable.

Further, in the above embodiment, light is emitted from the light emitting unit toward the predetermined position in the paper feed direction on the platen and a plurality of different positions in the main scanning direction, and the emitted light is received. Although it is determined whether or not the printing paper is in the light traveling direction based on the output value of the light receiving unit, the present invention is not limited to this. For example, the printing paper emits light based on the output value of the light receiving unit that emits light from the light emitting unit toward the predetermined position in the paper feeding direction on the platen and is the only position. It may be determined whether or not the vehicle is in the traveling direction.
However, in this way, even if the printing paper is tilted, the embodiment described above can be surely detected on the upstream side of the printing paper in the paper feeding direction. Is more desirable.

In the above-described embodiment, the light-emitting unit and the light-receiving unit are provided in the carriage that can move in the main scanning direction, and the predetermined feeding direction in the paper feeding direction on the platen while moving the carriage in the main scanning direction. Whether or not the printing paper is in the light traveling direction based on the output value of the light receiving section that emits light from the light emitting section toward a plurality of positions that are different in the main scanning direction, and receives the emitted light However, the present invention is not limited to this. For example, the light emitting part and the light receiving part are fixed, and light is emitted from the light emitting part toward the predetermined position in the paper feeding direction on the platen and a plurality of different positions in the main scanning direction. It may be determined whether or not the printing paper is in the light traveling direction based on the output value of the light receiving unit that has received the light.
However, in this way, when emitting light from the light emitting unit toward a plurality of different positions in the main scanning direction, it is not necessary to change the light emitting direction for each of the positions. Is more desirable.

In the above embodiment, the carriage includes a print head, and the carriage moves in the main scanning direction while moving the carriage in the main scanning direction, and a plurality of different positions in the main scanning direction. The light is emitted from the light emitting unit toward the light source, and based on the output value of the light receiving unit that has received the emitted light, it is determined whether the printing paper is in the light traveling direction, and from the nozzle provided in the print head Although printing is performed on printing paper by discharging ink, the present invention is not limited to this. For example, the carriage, the light emitting unit, and the light receiving unit may be configured to be separately movable in the main scanning direction.
However, in this case, the above embodiment is preferable in that the carriage, the light emitting unit, and the moving mechanism of the light receiving unit can be shared.

Moreover, in the said embodiment, although borderless printing was performed, it is not limited to this.
However, in the case of borderless printing, printing is performed on the entire surface of the printing paper, so there is a situation in which ink is ejected from nozzles that do not face the printing paper when a part of the nozzle surface does not face the printing paper. Since it is easy, the merit by the said means becomes larger.

=== Configuration of Computer System etc. ===
Next, an embodiment of a computer system which is an example of an embodiment according to the present invention will be described with reference to the drawings.

  FIG. 11 is an explanatory diagram showing an external configuration of the computer system. The computer system 1000 includes a computer main body 1102, a display device 1104, a printer 1106, an input device 1108, and a reading device 1110. In this embodiment, the computer main body 1102 is housed in a mini-tower type housing, but is not limited thereto. The display device 1104 is generally a CRT (Cathode Ray Tube), a plasma display, a liquid crystal display device, or the like, but is not limited thereto. As the printer 1106, the printer described above is used. In this embodiment, the input device 1108 is a keyboard 1108A and a mouse 1108B, but is not limited thereto. In this embodiment, the reading device 1110 uses a flexible disk drive device 1110A and a CD-ROM drive device 1110B. However, the reading device 1110 is not limited to this. For example, an MO (Magneto Optical) disk drive device or a DVD (Digital Versatile) is used. Disk) etc. may be used.

  FIG. 12 is a block diagram showing a configuration of the computer system shown in FIG. An internal memory 1202 such as a RAM and an external memory such as a hard disk drive unit 1204 are further provided in a housing in which the computer main body 1102 is housed.

  In the above description, the printer 1106 is connected to the computer main body 1102, the display device 1104, the input device 1108, and the reading device 1110 to configure the computer system. However, the present invention is not limited to this. Absent. For example, the computer system may include a computer main body 1102 and a printer 1106, and the computer system may not include any of the display device 1104, the input device 1108, and the reading device 1110.

  Further, for example, the printer 1106 may have a part of each function or mechanism of the computer main body 1102, the display device 1104, the input device 1108, and the reading device 1110. As an example, the printer 1106 includes an image processing unit that performs image processing, a display unit that performs various displays, a recording medium attachment / detachment unit for attaching / detaching a recording medium that records image data captured by a digital camera or the like. It is good also as a structure to have.

  The computer system realized in this way is a system superior to the conventional system as a whole system.

11 Linear encoder
12 Code Plate for Linear Encoder 13 Rotary Encoder 20 Color Inkjet Printer 21 CRT
DESCRIPTION OF SYMBOLS 22 Paper stacker 24 Paper feed roller 25 Pulley 26 Platen 28 Carriage 29 Reflection type optical sensor 30 Carriage motor 31 Paper feed motor 32 Pull belt 34 Guide rail 36 Print head 38 Light emitting part 40 Light receiving part 50 Buffer memory 52 Image buffer 54 System controller 56 Main memory 58 EEPROM
61 Main Scan Drive Circuit 62 Sub Scan Drive Circuit 63 Head Drive Circuit 65 Reflective Optical Sensor Control Circuit 66 Electrical Signal Measuring Unit 90 Computer 91 Video Driver 95 Application Program 96 Printer Driver 97 Resolution Conversion Module 98 Color Conversion Module 99 Halftone Module 100 Rasterizer 101 User interface display module 102 UI printer interface module 1000 Computer system 1102 Computer main body 1104 Display device 1106 Printer 1108 Input device 1108A Keyboard 1108B Mouse 1110 Reading device 1110A Flexible disk drive device 1110B CD-ROM drive device 1202 Internal memory 1204 Hard disk drive unit Door

Claims (11)

A feeding mechanism for feeding the medium in a predetermined feeding direction;
A discharge head having a plurality of nozzles arranged along the feed direction for discharging a liquid;
In a liquid ejection apparatus that ejects liquid from the nozzle to the medium,
A sensor for detecting the presence or absence of the medium, and a controller for controlling the discharge of the liquid from the nozzle,
The controller is
Based on the change in the electrical signal due to the sensor no longer detecting the portion of the medium positioned upstream in the feed direction, the portion of the medium positioned upstream of the feed direction is It is determined whether or not it has reached the downstream side in the feed direction from the nozzle located upstream,
When it is determined that the portion of the medium located on the upstream side in the feed direction has reached the downstream side in the feed direction rather than the nozzle located on the most upstream side in the feed direction,
A liquid ejecting apparatus, wherein after a predetermined amount of the medium is fed in the feeding direction, liquid is not ejected from nozzles located on the upstream side in the feeding direction among the plurality of nozzles. The liquid ejection apparatus according to claim 1,
Of the plurality of nozzles, based on determining that the portion of the medium located on the upstream side in the feed direction has reached the downstream side in the feed direction rather than the nozzle located on the most upstream side in the feed direction, A liquid ejecting apparatus, wherein liquid is prevented from being ejected from a nozzle located on the most upstream side in the feeding direction and a nozzle having a distance in the feeding direction from the nozzle within a predetermined distance. The liquid ejection apparatus according to claim 2, wherein
After determining that a portion of the medium located on the upstream side in the feed direction has reached the downstream side in the feed direction with respect to the nozzle located on the most upstream side in the feed direction, the medium is moved in the feed direction by the feed mechanism. The liquid ejection apparatus is characterized in that the liquid ejection to the medium is completed by repeating a procedure for feeding to the medium and a process for ejecting the liquid onto the medium by moving the ejection head a predetermined number of times. The liquid ejection apparatus according to any one of claims 1 to 3,
Of the ends of the medium, by determining whether an end located on the upstream side in the feed direction has passed a predetermined position in the feed direction, a portion located on the upstream side in the feed direction of the medium is It determines with having reached the said feed direction downstream rather than the nozzle located in the said feed direction most upstream, The liquid discharge apparatus characterized by the above-mentioned. The liquid ejection apparatus according to claim 4, wherein
A medium support part for supporting the medium, a light emitting means for emitting light toward the medium support part, and a light receiving sensor for receiving light emitted by the light emitting means,
By determining whether or not the medium is in the traveling direction of the light emitted from the light emitting means based on the output value of the light receiving sensor, the end located on the upstream side in the feeding direction among the ends of the medium Determining whether or not the liquid has passed a predetermined position in the feed direction. The liquid ejection apparatus according to claim 5, wherein
The light receiving sensor that emits the light from the light emitting unit toward the predetermined position in the feeding direction on the medium support unit and that is different in a main scanning direction, and receives the emitted light. A liquid ejection apparatus that determines whether the medium is in a traveling direction of the light based on an output value. The liquid ejection apparatus according to claim 6, wherein
The light emitting means and the light receiving sensor are provided on a moving member movable in the main scanning direction,
While moving the moving member in the main scanning direction, the light emitting unit emits the light toward the predetermined position in the feeding direction on the medium support portion and a plurality of different positions in the main scanning direction. A liquid ejecting apparatus that determines whether or not the medium is in a traveling direction of the light based on an output value of the light receiving sensor that receives the emitted light. The liquid ejection device according to claim 7, wherein
The moving member includes the ejection head,
While moving the moving member in the main scanning direction,
Based on an output value of the light receiving sensor that emits the light from the light emitting unit toward the predetermined position in the feeding direction and different positions in the main scanning direction, and receives the emitted light. Determining whether the medium is in the direction of travel of the light, and
A liquid discharge apparatus for discharging a liquid to the medium from a nozzle provided in the discharge head. The liquid ejection apparatus according to any one of claims 1 to 8,
A liquid ejecting apparatus for ejecting liquid on the entire surface of the medium. The liquid ejection device according to any one of claims 1 to 9,
The liquid is ink;
The liquid ejecting apparatus, wherein the liquid ejecting apparatus is a printing apparatus that performs printing on a printing medium as the medium by ejecting ink from the nozzles.   A computer main body, a display device connectable to the computer main body, and a liquid ejection device connectable to the computer main body, the feeding mechanism for feeding the medium in a predetermined feeding direction, and the feeding for discharging the liquid A liquid ejection device that ejects liquid from the nozzles to the medium, the sensor for detecting the presence or absence of the medium, and the nozzles A controller for controlling the discharge of the liquid from the medium, the controller based on a change in an electric signal due to the sensor no longer detecting a portion of the medium located upstream in the feeding direction. It is determined whether or not the portion located on the upstream side in the feed direction has reached the downstream side in the feed direction with respect to the nozzle located on the most upstream side in the feed direction If it is determined that the portion of the medium located upstream in the feed direction has reached the downstream side of the feed direction relative to the nozzle located upstream in the feed direction, the medium is moved in the feed direction. A computer system comprising: a liquid ejecting apparatus that prevents liquid from being ejected from a nozzle located upstream in the feeding direction among the plurality of nozzles after feeding a predetermined amount. .

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