JP3972953B2 - Liquid ejection device - Google Patents

Description

  The present invention relates to a liquid ejection apparatus.

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 order to solve such a problem, it is determined whether or not an end of the printing paper located upstream in the paper feeding direction has passed a predetermined position in the paper feeding direction, and a plurality of nozzles are determined based on the determination result. Among them, it is possible to take measures to prevent ink from being ejected from nozzles located upstream in the paper feed direction.

  However, although details will be described later, when such a measure is taken, there is a possibility that a problem that ink is wasted is generated. In addition, a margin portion is generated on the printing paper, and there is a possibility that a larger margin must be secured in order to avoid the occurrence of the margin portion.

  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 in which nozzles located on the most upstream side in the feed direction are arranged at more ideal positions.

The main present invention comprises a plurality of nozzles for discharging a liquid, a movable discharge head, a feed mechanism for feeding a medium in a predetermined feed direction, a medium support part for supporting the medium, An output value of the light receiving sensor, comprising: a light emitting means for emitting light toward the medium support portion; and a light receiving sensor for receiving the light emitted by the light emitting means. By detecting whether or not the medium is in the traveling direction of the light emitted from the light emitting means, an end located on the upstream side in the feeding direction among the ends of the medium is In the liquid ejection apparatus that determines whether or not a predetermined position has been passed, and based on the determination result, prevents the liquid from being ejected from the nozzles located upstream in the feed direction among the plurality of nozzles, the detection Means Among the plurality of nozzles, the nozzle positioned in the feeding direction most upstream side, and a liquid discharge apparatus characterized by being arranged in parallel in the main scanning direction.
Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

At least the following will be made clear by the description of the present specification and the accompanying drawings.
A plurality of nozzles for discharging liquid, a movable discharge head, a feed mechanism for feeding a medium in a predetermined feed direction, a medium support part for supporting the medium, and the medium support part Detecting means comprising: a light emitting means for emitting light toward the light; and a light receiving sensor for receiving the light emitted by the light emitting means, and the medium based on an output value of the light receiving sensor By detecting whether the light emitted from the light emitting means is in the traveling direction of the light, the end located on the upstream side in the feeding direction among the ends of the medium has passed a predetermined position in the feeding direction. In the liquid ejecting apparatus that prevents liquid from being ejected from the nozzles located upstream in the feed direction among the plurality of nozzles based on the determination result, the detecting means includes Noz Of the nozzle positioned in the feeding direction most upstream side, the liquid ejection apparatus characterized by being arranged side by side in the main scanning direction.
In this way, it is possible to realize a liquid ejection apparatus in which the nozzle located on the most upstream side in the feed direction is arranged at a more ideal position.

=== 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 as an example of a detection means 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, as shown in the drawing, the reflective optical sensor 29 includes a nozzle located on the most upstream side in the paper feed direction among the plurality of nozzles provided in the print head 36, and the main scanning direction. Are provided side by side.

=== 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 the 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).

  As described above, in the present embodiment, the reflective optical sensor 29 is aligned with the nozzle located on the most upstream side in the paper feed direction among the plurality of nozzles provided in the print head 36 in the main scanning direction. Therefore, the predetermined position in the paper feed direction corresponds to the position of the 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 moves 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 feed direction matches the position of the nozzle # 360 in the paper feed 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.

  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.

== About the detection error when detecting the portion of the printing paper located upstream in the paper feed direction ==
Next, a detection error when detecting a portion located on the upstream side in the paper feeding direction of the printing paper will be considered. As described above, in step S14, by determining whether or not the lower end of the printing paper P has passed a predetermined position in the paper feeding direction (in this embodiment, the position in the paper feeding direction of the nozzle # 360), A portion of the printing paper P located upstream in the paper feed direction is detected, but a detection error occurs during the detection.

  This will be described with reference to FIG. FIG. 11 is a diagram schematically showing the positional relationship between the nozzles of the print head 36 and the printing paper P. FIG.

  In FIG. 11, the small rectangle shown on the left represents the nozzles of the print head 36. The numbers in the rectangles are nozzle numbers and correspond to the nozzle numbers shown in FIG. In FIG. 11, 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. 11, 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. Although two print sheets P are shown in FIG. 11, the lower end position (hereinafter also referred to as the first position) of the print sheet P shown on the downstream side in the paper feed direction is a distance of 9 · D. It is downstream of the reflective optical sensor 29 in the paper feeding direction. Further, the lower end position (hereinafter also referred to as a second position) of the printing paper P shown on the upstream side in the paper feeding direction is upstream of the reflective optical sensor 29 by the distance of 9 · D.

  As described above, a detection error occurs when detecting a portion of the printing paper P located upstream in the paper feed direction, but printing when a portion located upstream in the paper feed direction is detected due to the detection error. The lower end position of the paper P varies in the range from the first position to the second position. That is, no matter where the lower end position of the printing paper P is located upstream of the first position, the portion of the printing paper P located upstream in the paper feed direction may not be detected. In addition, even if the lower end position of the printing paper P is located at any position downstream of the second position, a portion of the printing paper P located upstream in the paper feeding direction may be detected.

  Also, as shown in FIG. 11, in the present embodiment, the position of the nozzle (nozzle # 360) located on the most upstream side in the paper feed direction is upstream of the first position and the first position. It is on the downstream side from the two positions, and is in the middle between the first position and the second position.

  Thus, the position in the paper feed direction of the nozzle (nozzle # 360) located on the most upstream side in the paper feed direction is upstream from the first position and downstream from the second position. Benefits.

  This will be described with reference to FIGS. 12 and 13 are diagrams schematically showing the positional relationship between the nozzles of the print head 36 and the printing paper P. FIG. FIGS. 12 and 13 are views corresponding to FIG. 11, but the first position or the second position, and the position of the nozzle (nozzle # 360) located on the most upstream side in the paper feed direction in the paper feed direction. Is different from FIG. 11.

  First, attention is focused on FIG. In the example of FIG. 12, the position in the paper feed direction of the nozzle (nozzle # 360) located on the most upstream side in the paper feed direction is upstream of the first position and the second position. In other words, the position of the nozzle # 360 in the paper feed direction is always determined when the portion of the print paper P located upstream in the paper feed direction is detected regardless of the fluctuation due to the detection error of the lower end position of the print paper P. That is, it is upstream of the lower end position of the printing paper P.

  In the case of applying the above-described method for preventing ink from being ejected from the nozzle located upstream in the paper feeding direction to this example, for example, compared to the example of FIG. Since they do not face each other, the number of nozzles that eject ink increases without the need to eject ink. Such an increase in the number of nozzles causes the disadvantage of wasted consumption of ink.

  Next, pay attention to FIG. In the example of FIG. 13, the position in the paper feed direction of the nozzle (nozzle # 360) located on the most upstream side in the paper feed direction is downstream of the first position and the second position. In other words, the position of the nozzle # 360 in the paper feed direction is always determined when the portion of the print paper P located upstream in the paper feed direction is detected regardless of the fluctuation due to the detection error of the lower end position of the print paper P. That is, it is on the downstream side of the lower end position of the printing paper P.

  In this example, when applying the above-described method for preventing ink from being ejected from the nozzle located upstream in the paper feed direction, it is necessary to eject ink while facing the printing paper. However, there are nozzles that do not discharge ink. Therefore, a margin portion is generated on the printing paper due to the operation of the nozzle. In addition, in order to avoid the occurrence of the margin part, there arises a disadvantage that a larger margin must be secured by setting a larger value to the predetermined amount described above.

  Compared to these two examples, in the example shown in FIG. 11, the position of the nozzle (nozzle # 360) located on the most upstream side in the paper feeding direction is upstream of the first position, and Since it exists in the downstream from said 2nd position, each inconvenience demonstrated about the said 2 example is reduced. That is, according to the example shown in FIG. 11, it is possible to realize a printer in which the nozzle located on the most upstream side in the paper feeding direction is arranged at an ideal position in consideration of the inconvenience.

=== 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, cloth, metal thin 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. .

In the above embodiment, the position of the nozzle located on the most upstream side in the paper feed direction among the plurality of nozzles is in the middle between the first position and the second position. However, the present invention is not limited to this, and may be located upstream from the first position and downstream from the second position.
However, if the position in the paper feed direction of the nozzle located on the most upstream side in the paper feed direction is exactly halfway between the first position and the second position, the above two types of inconveniences are most effectively reduced. The above embodiment is preferable in that a printer in which nozzles located on the most upstream side in the feed direction are arranged at more ideal positions can be realized.

In the above embodiment, the reflective optical sensor is provided side by side in the main scanning direction with the nozzle located on the most upstream side in the paper feeding direction, but the present invention is not limited to this.
However, in this way, the position in the paper feed direction of the nozzle located on the most upstream side in the paper feed direction is almost certainly upstream from the first position and downstream from the second position. In addition, if the error to the upstream side is equal to the error to the downstream side from the position in the paper feed direction of the reflective optical sensor (in the example of FIG. 11, the error is both 9 · D). It is exactly halfway between the first position and the second position. Therefore, the above embodiment is more preferable in that the above-described effect can be obtained.

Further, in the above-described embodiment, the part 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; Although the ink is not ejected from the nozzle in which the distance in the paper feed direction from the nozzle is within a predetermined distance, 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 consumption of ink can be further reduced.

In the above-described embodiment, after a portion of the printing paper located upstream in the paper feeding direction is detected, the printing paper is fed by the paper feeding motor in the paper feeding direction, and the print head is moved to perform printing. The procedure for printing on paper is repeated a predetermined number of times to finish printing on the printing paper, but 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. 14 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. Disk) etc. may be used.

  FIG. 15 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.

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. 3 is a diagram schematically illustrating the positional relationship between the nozzles of the print head and the printing paper P. FIG. 3 is a diagram schematically illustrating the positional relationship between the nozzles of the print head and the printing paper P. FIG. 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.

Explanation of symbols

11 Linear Encoder 12 Linear Encoder Sign Plate 13 Rotary Encoder 20 Color Inkjet Printer 21 CRT 22 Paper Stacker 24 Paper Feed Roller 25 Pulley 26 Platen 28 Carriage 29 Reflective Optical Sensor 30 Carriage Motor 31 Paper Feed Motor 32 Pulling Belt 34 Guide rail 36 Print head 38 Light emitting unit 40 Light receiving unit 50 Buffer memory 52 Image buffer 54 System controller 56 Main memory 58 EEPROM 61 Main scanning drive circuit
62 Sub-scanning 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 Reader 1110A Flexible disk drive device 1110B CD-ROM drive device 1202 Internal memory 1204 Hard disk drive unit

Claims (1)

A movable ejection head comprising a plurality of nozzles for ejecting liquid and movable;
A feeding mechanism for feeding the medium in a predetermined feeding direction;
A medium support for supporting the medium;
A detecting means comprising: a light emitting means for emitting light toward the medium support portion; and a light receiving sensor for receiving the light emitted by the light emitting means,
By detecting 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 Determines whether or not the liquid has passed a predetermined position in the feed direction, and based on the determination result, the liquid that prevents discharge of the liquid from the nozzles located upstream in the feed direction among the plurality of nozzles In the discharge device,
The liquid ejecting apparatus according to claim 1, wherein the detection unit is provided side by side in the main scanning direction with a nozzle located on the most upstream side in the feeding direction among the plurality of nozzles.

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