JP2009101701A - Printing by positioning printing paper by sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To print image data on a print sheet while positioning the sheet accurately. <P>SOLUTION: The print sheet P is guided by guides 29a and 29b, and fed in the subscanning direction so that both side ends are located above the left groove 26a and the right groove 26b of a platen 26. A carriage 31 equipped with a photoreflector 33 is arranged at a position shown by a dashed line. The photoreflector 33 detects whether the print sheet P exists at the joint 26d of the left groove 26a and a downstream side groove 26r. When the forward end of the print sheet P is detected by the photoreflector 33, feeding in the subscanning direction is stopped and printing at the upper end Pf (lower end in Fig. 1) of the print sheet P is started by a part of nozzles above the downstream side groove 26r. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for recording dots on the surface of a recording medium using a dot recording head, and more particularly to a technique for performing printing by accurately positioning printing paper.

  In recent years, printers that eject ink from nozzles of a print head have become widespread as computer output devices. FIG. 15 is a side view showing the periphery of a print head of a conventional printer. The printing paper P is fed in the direction of arrow A by the upstream paper feed rollers 25p and 25q arranged upstream of the platen 26o and the downstream paper feed rollers 25r and 25s arranged downstream of the platen 26o. It stops at the position. The printing paper P is supported on the platen 26o so as to face the head 28o. Thereafter, a large number of ink droplets Ip are ejected from the print head toward a predetermined position on the platen 26o while feeding the printing paper little by little in the direction of arrow A. These ink droplets Ip land on the printing paper P on the platen 26o, and an image is recorded on the printing paper.

Japanese Patent Laid-Open No. 7-214822

  In the printer as described above, as shown in FIG. 15, when the printing paper is deviated from the assumed position indicated by the broken line, an image is not formed at the assumed position on the printing paper. In addition, an image that is scheduled to be formed near the edge of the printing paper may protrude from the printing paper. In such a case, as shown in FIG. 15, the ink droplets are detached from the edge of the printing paper to be originally landed and landed on the platen, and then the printing paper passing on the platen becomes dirty.

  The present invention has been made to solve the above-described problems in the prior art, and an object of the present invention is to provide a technique for performing printing by accurately positioning printing paper.

  In order to solve at least a part of the above-described problems, the present invention employs the following configuration. The dot recording apparatus of the present invention is a dot recording apparatus that records dots on the surface of a print medium using a dot recording head provided with a plurality of dot forming elements that eject ink droplets. In addition, a main scanning drive unit that drives the dot recording head with respect to the printing medium to perform main scanning, and forms dots by driving at least some of the plurality of dot forming elements during the main scanning. A head driving unit for driving, a sub-scanning driving unit for performing sub-scanning by driving the printing medium in a direction crossing the main scanning direction, a detection unit for detecting the presence or absence of the printing medium at a predetermined detection point, and each unit A control unit for controlling. The detection unit is provided at a position that does not intersect with the trajectory of the ink droplet ejected from the dot forming element during the main scanning. According to such an aspect, by detecting the print medium by the detection unit, the print medium can be accurately positioned to record dots, and an image can be formed on the record medium.

  In the above dot recording apparatus, it is preferable to perform the following printing. That is, the sub-scan of the print medium is started from a state where there is no print medium at the detection point. When the detection unit detects the print medium, the sub-scan of the print medium is stopped at a predetermined sub-scan position with respect to the sub-scan direction. Thereafter, main scanning is started while ejecting ink droplets from the dot forming elements in a state where the print medium is at a predetermined sub-scanning position. According to such printing, it is possible to position the print medium based on whether or not the leading end of the print medium has reached a predetermined detection point. Therefore, the printing medium can be accurately positioned in the sub scanning direction.

  Moreover, it is preferable that a detection part is equipped with the light emission part which inject | emits light toward a predetermined | prescribed detection point, and the light-receiving part which receives the reflected light which light reflected on the printing medium and reflected. In this way, the print medium can be detected without touching the print medium, and there is no hindrance when dots are recorded on the print medium.

  The detection unit is preferably provided so as to be driven integrally with the dot recording head during main scanning. With such an aspect, the dot recording head and the detection unit do not interfere with each other in the main scanning.

  Further, the position of the detection unit is set to a position in the vicinity of the dot forming element located at the downstream end in the sub scanning direction among the dot forming elements used for printing in the sub scanning direction. Is preferred. With such an aspect, the print medium can be positioned by detecting the presence or absence of the print medium in the vicinity of the dot forming element that prints the leading end of the print medium. Therefore, the print medium can be accurately positioned with respect to the dot forming element that prints the leading end of the print medium.

  The dot recording apparatus preferably includes a platen that extends in the main scanning direction so as to face the dot forming element in at least a part of the main scanning path and supports the print medium. And it is preferable to set it as the following structures. That is, the platen has a downstream groove portion that extends in the main scanning direction at a position facing a dot forming element located at the downstream end in the sub-scanning direction among at least a plurality of dot forming elements. Shall. The detection point of the detection unit is set to a predetermined position within the opening of the downstream groove portion and within the range where the dot forming element exists in the sub-scanning direction. According to such an aspect, it is possible to detect that the leading end of the recording medium is positioned at the opening of the downstream groove portion, and to start recording dots near the leading end of the recording medium by the dot forming element.

  Further, the platen further has a lateral groove portion provided in a range including at least the landing range of the ink droplet from the dot forming element in the sub-scanning direction and connected to the downstream groove portion. Such a configuration is preferable. That is, the dot recording apparatus further includes a guide unit for positioning the print medium at a predetermined main scanning position in the main scanning direction during the sub-scanning. The predetermined main scanning position at which the guide unit positions the print medium is positioned within the main scanning process of the dot recording head with respect to the main scanning direction, and one side edge of the printing medium in the main scanning direction. The part is a position located on the opening of the side groove part. And the detection point of a detection part is made into the predetermined position of the connection part of a side groove part and a downstream groove part. According to such an aspect, it is detected that the leading edge of the recording medium is located at the opening of the downstream groove and the side edge is located above the opening of the lateral groove, and recording of dots onto the recording medium is started. can do.

  In addition, it is preferable to provide a pair of side groove portions including a first side groove portion and a second side groove portion. The first side groove portion and the second side groove portion are such that when the print medium is at a predetermined main scanning position, one side end portion in the main scanning direction of the print medium is the first side groove portion. It is preferable to be provided so that the other side end portion is located on the second side groove portion. According to such an aspect, when it is detected that the leading end of the recording medium is positioned at the opening of the downstream groove portion and one side end portion is positioned above the opening of the first side groove portion, The end portion is located on the opening of the second lateral groove portion. Then, after confirming such an arrangement, it is possible to start recording dots on the recording medium.

Note that the present invention can be realized in various modes as described below.
(1) A dot recording device, a printing control device, and a printing device.
(2) A dot recording method, a printing control method, and a printing method.
(3) A computer program for realizing the above apparatus and method.
(4) A recording medium on which a computer program for realizing the above apparatus and method is recorded.
(5) A data signal embodied in a carrier wave including a computer program for realizing the above-described apparatus and method.

Hereinafter, embodiments of the present invention will be described in the following order based on examples.
A. Summary of embodiment:
B. Overall configuration of the device:
C. Printing paper layout:
D. Top edge processing:
E. Printing the left and right edges:
F. Bottom edge processing:
G. Variations:

A. Summary of embodiment:
FIG. 1 is a plan view schematically showing a structure around a platen of an ink jet printer according to an embodiment of the present invention. In FIG. 1, the printing paper P is sub-scanned in the direction of arrow SS from the top to the bottom. At that time, the printing paper P is guided by the guides 29a and 29b, and is sub-scan fed so that both side edges Pa and Pb are positioned on the left groove 26a and the right groove 26b of the platen 26. On the other hand, when the print paper P is sub-scanned toward the platen 26, the carriage 31 of the print head is disposed at a position indicated by a broken line. The carriage 31 includes a photo reflector 33 on the surface facing the platen 26. The photo reflector 33 is provided on the carriage 31 at a position slightly upstream (a direction opposite to the arrow SS) from the nozzle at the downstream end in the sub-scanning direction. The photo reflector 33 detects whether or not the printing paper P is present at a predetermined point DP of the connecting portion 26d between the left groove portion 26a and the downstream groove portion 26r.

  When the printing paper P is sub-scanned in the direction of the arrow SS and the front end thereof is detected by the photo reflector 33, the sub-scanning feeding of the printing paper P is stopped. And printing of the upper end part Pf (it becomes a lower end in FIG. 1) of the printing paper P is started by a part of nozzles on the downstream side groove part 26r among the nozzles on the print head. Since the nozzles on the print head are provided beyond the upper end portion Pf of the print paper P in the direction of the arrow SS, an image can be formed without creating a margin at the upper end of the print paper P. Further, since the nozzles used for printing are the nozzles on the downstream side groove 26r, even when the ink droplets deviate from the printing paper P, the ink droplets land on the downstream side groove 26r, and the center of the platen 26 There is no landing on the part 26c. Therefore, the lower surface of the printing paper P is not soiled by the ink droplets that have landed on the central portion 26c of the platen 26. Similarly, the left and right side edges of the printing paper P are printed by nozzles located on the left groove 26a and the right groove 26b during main scanning. Therefore, it is possible to print the left and right side edges without margins without staining the central portion 26c of the platen 26.

B. Device configuration:
FIG. 2 is a block diagram illustrating a software configuration of the printing apparatus. 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 image data D to be transferred to the printer 22 is output from the application program 95 via these drivers. An application program 95 that performs image retouching and the like reads an image from the scanner 12, performs predetermined processing on the image, and displays the image on the CRT 21 via the video driver 91. Data ORG supplied from the scanner 12 is original color image data ORG that is read from a color original and includes three color components of red (R), green (G), and blue (B).

  When the application program 95 issues a print command, the printer driver 96 of the computer 90 receives image data from the application program 95, and signals that can be processed by the printer 22 (here, cyan, magenta, yellow, light cyan, light Multi-valued signals for magenta and black colors). In the example shown in FIG. 2, the printer driver 96 includes a resolution conversion module 97, a color correction module 98, a halftone module 99, and a rasterizer 100. A color correction table LUT and a dot formation pattern table DT are also stored.

  The resolution conversion module 97 converts the resolution of color image data (consisting of three colors of RGB) handled by the application program 95, that is, the number of pixels per unit length into a resolution that can be handled by the printer driver 96. The color correction module 98 refers to the color correction table LUT, and converts the resolution-converted image data into cyan (C), magenta (M), light cyan (LC), and light magenta (used by the printer 22 for each pixel. LM), yellow (Y), and black (K).

  The color-corrected data has a predetermined gradation value. The printer 22 expresses this gradation value by forming dots in a dispersed manner. When the halftone module 99 performs halftone processing on the data, the data becomes data that allows the printer 22 to express a gradation value by forming such dots. The halftone module 99 refers to the dot formation pattern table DT, sets the dot formation pattern of each ink dot according to the tone value of the image data, and then executes this halftone process. The processed image data is rearranged in the order of transfer to the printer 22 by the rasterizer 100, and output as final print data PD. The print data PD includes raster data indicating the dot recording state during each main scan and data indicating the sub-scan feed amount. In this embodiment, the printer 22 only serves to form dots according to the print data PD and does not perform image processing. However, the printer 22 may perform these processes.

  Next, a schematic configuration of the printer 22 will be described with reference to FIG. As shown in the figure, the printer 22 includes a mechanism for transporting the printing paper P by a paper feed motor 23, guides 29a and 29b (not shown in FIG. 3) for guiding the printing paper P during transportation, and a carriage motor. 24, a mechanism for reciprocating the carriage 31 in the axial direction of the platen 26, a mechanism for driving the print head 28 mounted on the carriage 31 to eject ink and forming ink dots, and the paper feed motor 23, The control circuit 40 controls the exchange of signals with the carriage motor 24, the print head 28, and the operation panel 32.

  The mechanism for reciprocating the carriage 31 in the axial direction of the platen 26 is constructed in parallel with the axis of the platen 26 and is an endless drive belt between the carriage shaft 24 and the carriage motor 24 slidably holding the carriage 31. 36, a pulley 38 for extending 36, a position detection sensor 39 for detecting the origin position of the carriage 31, and the like.

  The carriage 31 is a color ink containing a black ink (K) cartridge 71 and six inks of cyan (C), light cyan (LC), magenta (M), light magenta (LM), and yellow (Y). Cartridge 72 can be mounted. A total of six ink ejection heads 61 to 66 are formed on the print head 28 below the carriage 31, and introduction pipes 67 that guide ink from the ink tanks to the heads for the respective colors are formed at the bottom of the carriage 31. It is erected. When the black (K) ink cartridge 71 and the color ink cartridge 72 are mounted on the carriage 31 from above, the introduction pipe 67 is inserted into the connection hole provided in each cartridge, and the ejection heads 61 to 66 are ejected from each ink cartridge. Ink can be supplied to the printer.

  FIG. 4 is an explanatory diagram showing in detail the structure of the piezo element PE and the nozzle Nz. In each color head 61 to 66 provided at the lower part of the carriage 31, a piezo element PE which is one of electrostrictive elements and excellent in responsiveness is arranged for each nozzle. As shown in the upper part of FIG. 4, the piezo element PE is disposed at a position in contact with the ink passage 68 that guides ink to the nozzle Nz. As is well known, the piezo element PE is an element that transforms electro-mechanical energy at a very high speed because the crystal structure is distorted by application of a voltage. In the present embodiment, by applying a voltage having a predetermined time width between the electrodes provided at both ends of the piezo element PE, the piezo element PE extends for the voltage application time as shown in the lower part of FIG. One side wall of 68 is deformed. As a result, the volume of the ink passage 68 contracts according to the expansion of the piezo element PE, and the ink corresponding to the contraction becomes particles Ip and is ejected from the tip of the nozzle Nz at high speed. Printing is performed by the ink particles Ip soaking into the paper P mounted on the platen 26.

  FIG. 5 is an explanatory diagram showing the arrangement of the inkjet nozzles Nz in the ink ejection heads 61-66. These nozzles are arranged from six sets of nozzle arrays that eject ink for each color of black (K), cyan (C), light cyan (LC), magenta (M), light magenta (LM), and yellow (Y). Each of the 48 nozzles is arranged in a line at a constant nozzle pitch k. The “nozzle pitch” is a value indicating how many rasters (that is, how many pixels) the intervals in the sub-scanning direction of the nozzles arranged on the print head are. Here, the “raster” is a column of pixels arranged in the main scanning direction. The “pixel” is a square grid virtually defined on the print medium in order to define the position where the ink droplet is landed and the dot is recorded. For example, the pitch k of the nozzles arranged with an interval of 3 rasters therebetween is 4.

  FIG. 6 is an explanatory diagram showing an electrical configuration of the photo reflector. As shown in FIG. 5, a photo reflector 33 is provided on the lower surface of the carriage 31 at the same position as the nozzle # 4 in the sub-scanning direction. The photo reflector 33 may be provided in the vicinity of the nozzle # 1 located at the downstream end in the sub-scanning direction. For example, the photo reflector 33 may be upstream of the nozzle # 1 by several times the nozzle pitch. It is preferable to provide in. As shown in FIG. 6, the photoreflector 33 includes a light emitting diode 33d and a phototransistor 33t that are integrated. The light emitting diode 33d emits light toward a predetermined detection point, and the phototransistor 33t receives the reflected light and converts a change in the light amount into a change in current. The CPU 41 in the control circuit 40 determines whether or not a part of the printing paper P is at the detection point depending on whether or not the phototransistor 33t receives the reflected light reflected by the printing paper P.

  The photo reflector 33 corresponds to a “detecting unit” in the claims. The light emitting diode 33d corresponds to the “light emitting portion”, and the phototransistor 33t corresponds to the “light receiving portion”. In addition, the light emission part should just be what can emit light toward a predetermined | prescribed detection point, and can also be used as a laser. The light receiving section may be any photodiode as long as it can receive reflected light reflected by the light hitting the print medium.

  FIG. 7 is a plan view showing the periphery of the platen 26. The platen 26 is provided longer than the width of the printing paper P in the main scanning direction MS so as to face each nozzle of the print head 28 in the main scanning. In addition, upstream paper feed rollers 25 a and 25 b are provided upstream of the platen 26. The upstream paper feed roller 25a is a single drive roller, whereas the upstream paper feed roller 25b is a plurality of small rollers that rotate freely. Further, downstream paper feed rollers 25c and 25d are provided downstream of the platen. The downstream paper feed roller 25c is a plurality of rollers provided on the drive shaft, and the downstream paper feed roller 25d is a plurality of small rollers that freely rotate. The downstream paper feed roller 25c and the upstream paper feed roller 25a rotate in synchronization so that the outer peripheral speeds are equal.

  The print head 28 reciprocates in the main scanning on the platen 26 sandwiched between the upstream paper feed rollers 25a and 25b and the downstream paper feed rollers 25c and 25d. The printing paper P is held by the upstream paper feeding rollers 25 a and 25 b and the downstream paper feeding rollers 25 c and 25 d, and a portion therebetween is supported by the upper surface of the platen 26 so as to face the nozzle row of the printing head 28. Sub-scan feed is performed by the upstream paper feed rollers 25 a and 25 b and the downstream paper feed rollers 25 c and 25 d, and images are sequentially recorded by ink ejected from the nozzles of the print head 28.

  The platen 26 is provided with an upstream groove 26f and a downstream groove 26r on the upstream and downstream sides in the sub-scanning direction, respectively. The upstream groove 26f and the downstream groove 26r are provided longer than the width of the printing paper P in the main scanning direction. The downstream groove portion 26r is provided at a position facing a part of the nozzle group Nr on the downstream side including the nozzles at the downstream end among the nozzles N on the print head 28 (the nozzles indicated by hatching in FIG. 7). . However, the width of the downstream groove 26r is wider than the width of the nozzle group Nr in the sub-scanning direction. The upstream groove 26f is provided at a position facing a part of the upstream nozzle group Nf (not shown in FIG. 7) including the nozzles at the upstream end among the nozzles on the print head 28. The width of the upstream groove 26f is wider than the width of the nozzle group Nf in the sub-scanning direction.

  Further, the platen 26 is provided with a left groove portion 26a and a right groove portion 26b that extend in the sub-scanning direction so as to connect both ends of the upstream groove portion 26f and the downstream groove portion 26r. The left groove portion 26a and the right groove portion 26b are provided in a range in the sub-scanning direction longer than the landing range of the ink droplets from the nozzle row on the print head. The left groove portion 26a and the right groove portion 26b are provided so that the distance between the center lines (in the main scanning direction) is equal to the width of the printing paper P in the main scanning direction. When the printing paper P is at a predetermined main scanning position where the printing paper P is guided by the guides 29a and 29b, one side end Pa in the main scanning direction of the printing paper P is the left-hand groove 26a and the right-hand groove 26b. It is only necessary that the other side end portion Pb is located on the right groove portion 26b. Therefore, as described above, when the printing paper P is in a fixed position, the side edges of the printing paper P are located on the left groove 26a, in addition to the aspect in which the side edges are on the center line of the left groove 26a and the right groove 26b. You may provide so that it may be located inside the centerline of the right side groove part 26b.

  The upstream groove portion 26f, the downstream groove portion 26r, the left groove portion 26a, and the right groove portion 26b are connected to each other to form a quadrilateral groove portion. An absorbing member 27 for receiving the ink droplet Ip and absorbing it is disposed at the bottom.

  When the sub-scan feed is performed by the upstream paper feed rollers 25a and 25b and the downstream paper feed rollers 25c and 25d, the printing paper P passes over the openings of the upstream groove 26f and the downstream groove 26r. . Further, the printing paper P is positioned in the main scanning direction on the platen 26 by the guides 29a and 29b so that the left end Pa is located on the left groove 26a and the right end Pb is located on the right groove 26b. Has been.

  Next, the internal configuration of the control circuit 40 (see FIG. 3) of the printer 22 will be described. Inside the control circuit 40, in addition to the CPU 41, PROM 42, and RAM 43, a PC interface 45 that exchanges data with the computer 90, and a drive that outputs ink dot ON / OFF signals to the ink ejection heads 61 to 66. A buffer 44 is provided, and these elements and circuits are connected to each other by a bus. The control circuit 40 receives the dot data processed by the computer 90, temporarily stores it in the RAM 43, and outputs it to the driving buffer 44 at a predetermined timing.

  The printer 22 having the hardware configuration described above moves the carriage 31 back and forth by the carriage motor 24 while transporting the paper P by the paper feed motor 23 and simultaneously drives the piezo elements of the nozzle units of the print head 28. The ink droplets Ip are ejected to form ink dots to form a multicolor image on the paper P.

  In the printer of this embodiment, as will be described later, the upper end Pf of the printing paper P is printed on the downstream groove 26r, and the lower edge Pr is printed on the upstream groove 26f. In the vicinity of the lower end, a printing process different from the intermediate portion of the printing paper is performed. In this specification, the printing process in the middle part of the printing paper is called “intermediate processing”, the printing process in the vicinity of the upper edge of the printing paper is called “upper edge processing”, and the printing process in the vicinity of the lower edge of the printing paper is called “lower edge”. This is called “processing”. In addition, when the upper end process and the lower end process are collectively referred to as “upper / lower end process”.

  Further, the width W in the sub-scanning direction of the upstream groove 26f and the downstream groove 26r can be determined by the following equation.

  W = p × n + α

  Here, p is a single feed amount [inches] of the sub-scan feed in the upper and lower end processing. n is the number of sub-scan feeds performed in each of the upper end process and the lower end process. α is a sub-scan feed error assumed in each of the upper end process and the lower end process. The value of α in the lower end processing (upstream groove portion 26f) is preferably set larger than the value of α in the upper end processing (downstream groove portion 26r). If the width of the groove portion of the platen is determined by the above formula, it is possible to provide a groove portion having a width that can sufficiently receive ink droplets ejected from the nozzles during the upper and lower end processing.

C. Printing paper layout:
FIG. 8 is a plan view showing the arrangement of each part when the printing paper P is first arranged on the platen 26 in the ink jet printer. In FIG. 8, the printing paper P is sub-scanned in the direction of arrow SS from the top to the bottom. At that time, the printing paper P is guided by guides 29a and 29b (see FIG. 7), and is sub-scan fed so that both side ends are positioned on the left and right groove portions 26a and 26b of the platen 26.

  When the printing paper P is sub-scan fed toward the central portion 26c of the platen 26, the carriage 31 of the print head 28 is disposed at a position on the left side of the platen 26 as shown in FIG. When the carriage 31 is at the position shown in FIG. 8, the photo reflector 33 is located on a predetermined detection point DP in the connection portion 26d between the left groove portion 26a and the downstream groove portion 26r. At this position, the light emitting diode 33d of the photo reflector 33 can emit light toward the detection point DP. This detection point DP is a predetermined position within the range where the nozzles on the print head 28 exist with respect to the position in the sub-scanning direction. The CPU 41 can detect whether or not the printing paper P is present at the detection point DP by using the photo reflector 33.

  Since the photo reflector 33 can detect the printing paper without contacting the printing paper, unlike the case of the contact-type sensor, there is no hindrance in the subsequent printing. Further, since the photo reflector 33 is provided on the carriage, it does not intersect with the trajectory of the ink droplet in the main scanning. Therefore, there is little possibility that detection performance deteriorates due to ink. Since the detection point DP of the photo reflector 33 is a predetermined position within the range where the nozzles exist in the sub-scanning direction, the printing paper P is arranged near the position of the printing paper P when the printing paper P is detected. Then, if ink droplets are ejected from the nozzles, an image can be formed at the leading edge of the printing paper P without a blank space.

  First, from a state where there is no printing paper P on the platen 26, the printing paper P is sub-scanned in the direction of the arrow SS. When the leading edge is detected by the photo reflector 33, the sub-scan feed of the printing paper P is stopped. In the present embodiment, the photo reflector 33 is provided at the position of the nozzle # 4. The CPU 41 slightly performs sub-scan feed after the photo reflector 33 detects the printing paper P, and the position of the nozzle at the downstream end in the sub-scan direction (hereinafter, this nozzle is referred to as “lower end nozzle”). The sub-scan feed is stopped so that the upper end Pf of the printing paper P is positioned at a position upstream of the raster in the sub-scanning direction (the direction opposite to the arrow SS) by a few rasters. As a result of the sub-scan feed of the printing paper P as described above, the printing paper P is supported by the central portion 26c of the platen 26, and its upper end (the upper end is located on the lower side of the drawing in FIG. 8) is the downstream groove portion. It will be located on 26r. The left end Pa of the printing paper P is located on the left groove 26a, and the right end Pb is located on the right groove 26b.

  Thereafter, the carriage is moved to the right end side as shown in FIG. 7, and printing is started. That is, main scanning is performed while ejecting ink droplets from the nozzles. If the print paper P cannot be detected at the detection point DP by the photo reflector 33 even if the sub-scan feed of the print paper P is performed, the CPU 41 sends an error signal to the computer 90 to perform printing. Cancel.

D. Top edge processing:
In this embodiment, an image is recorded without a margin up to the upper end of the printing paper. At that time, the recording at the upper end portion Pf of the printing paper P is recorded by the nozzle Nr arranged at a position corresponding to the position on the downstream groove portion 26r in the sub-scanning direction. As shown in FIG. 7, some of the nozzles Nr including the lower end nozzle are located downstream of the upper end of the printing paper P in the sub-scanning direction (the direction of the arrow SS). In other words, the printing paper P is arranged so that the upper end Pf of the printing paper P is located upstream of the lower end nozzle in the sub-scanning direction.

  Theoretically, if the printing paper P is arranged with respect to the print head 28 so that the lower end nozzle is positioned at the position of the top edge of the printing paper P and dot recording is started, the upper end of the printing paper P is started. An image can be recorded without a margin until it is full. However, an error may occur in the feed amount during the sub-scan feed. Further, the ejection direction of the ink droplets may be shifted due to a manufacturing error of the print head 28 or the like. In this embodiment, the printing paper P is arranged so that the upper end Pf of the printing paper P is located upstream of the lower end nozzle, and the upper end portion Pf of the printing paper P is printed. For this reason, even when the landing position of the ink droplet on the printing paper is deviated, no margin is generated at the upper end of the printing paper.

  FIG. 9 is a side view showing the relationship between the print head 28 and the printing paper P at the start of printing. Here, in order to simplify the description, the number of nozzles will be described as eight. The central portion 26c of the platen 26 is provided in a range R26 from a position two rasters behind the # 2 nozzle of the print head 28 to a position two rasters ahead from the # 7 nozzle. And Therefore, even when ink droplets Ip are ejected from each nozzle in the absence of printing paper, ink droplets from the nozzles # 1, # 2, # 7, and # 8 do not land on the platen 26.

  In FIG. 7, the nozzle group Nr of the portion indicated by the oblique lines of the print head 28 is the portion where the nozzles # 1 and # 2 are located. A downstream groove 26r is provided below a portion through which these nozzles pass during main scanning. Then, when the upper end Pf of the printing paper P is on the downstream side groove 26r, printing is started. In the present embodiment, the upper end portion Pf of the printing paper P using the # 2 nozzle just above the upper end portion Pf of the printing paper P and the # 1 nozzle outside the upper end portion Pf of the printing paper P is used. Is printed, an image can be printed without creating a margin at the upper end of the printing paper P. Further, since the printing paper P is positioned using the photo reflector 33, the printing paper P can be accurately arranged with respect to the nozzle used for the upper end processing. Further, even when the position of the printing paper is shifted due to a sub-scan feed error or the like, since the nozzles # 1 and # 2 are located on the downstream groove 26r, the ink droplets land on the central portion 26c of the platen 26. There is nothing.

  FIG. 10 is a plan view showing the relationship between the image data D and the printing paper P. In this embodiment, the image data D is set beyond the upper end Pf of the printing paper P to the outside of the printing paper P. Similarly, for the lower end Pr, the left end Pa, and the right end Pb, the image data D is set beyond the end of the print paper P to the outside of the print paper P. Therefore, in this embodiment, the relationship between the size of the image data D and the printing paper P, and the assumed position of the image data D at the time of printing and the arrangement of the printing paper P is as shown in FIG. Since the left and right names of the left end Pa and the right end Pb correspond to the left and right names of the printer 22, on the printing paper P, the actual left and right names and the names of the left end Pa and the right end Pb are reversed. It has become.

E. Printing the left and right edges:
FIG. 11 is an explanatory diagram showing printing at the left and right end portions of the printing paper P. In the present embodiment, printing is performed so that no margin is provided at the left and right edges of the printing paper P throughout the entire recording of the image on the printing paper P, including the upper edge processing and the lower edge processing. At that time, in the main scanning, the print head 28 is sent to a position where all the nozzles are located outside the print paper P beyond the end of the print paper P for one end, and also for the other end. All nozzles are fed beyond the other end of the printing paper P to a position outside the printing paper P. The image data is not only when the nozzle Nz is on the printing paper P, but also when the nozzle Nz is at a position beyond the end of the printing paper P and on the left groove 26a or the right groove 26b. Ink droplets are ejected from the nozzle Nz according to D.

  By performing such printing, even when the printing paper P is slightly displaced in the main scanning direction, an image can be formed without creating margins on the left and right ends of the printing paper P. Further, the detection point DP of the photo reflector 33 is located at the connecting portion 26d between the left groove portion 26a and the downstream groove portion 26r, and printing is stopped when the printing paper P cannot be detected at the detection point DP. Also, the printing paper P can be placed at the correct position for printing. Further, since the nozzles for printing the both end portions of the printing paper are nozzles located on the left groove 26a or the right groove 26b, even when the ink droplets are separated from the printing paper P, the ink droplets are located in the central portion of the platen 26. It lands on the left groove 26a or the right groove 26b without landing on 26c. Therefore, the printing paper P is not soiled by ink droplets that have landed on the central portion 26c of the platen 26.

F. Bottom edge processing:
FIG. 12 is a plan view showing the relationship between the upstream groove 26f and the printing paper P when the lower end portion Pr of the printing paper P is printed. In the present embodiment, as in the case of the upper end, an image is recorded without a margin to the end of the printing paper P at the lower end. In FIG. 12, the portion of the nozzle group Nf indicated by diagonal lines of the print head 28 is a portion where the nozzle for performing the lower end processing is located. An upstream groove 26f is provided below a portion through which these nozzles pass during main scanning. When the lower end Pr of the printing paper P is at the position indicated by the alternate long and short dash line on the upstream groove 26f, the lower end Pr is printed, and then the printing ends. At this time, some of the nozzles in the nozzle group Nf are located upstream of the lower end of the printing paper P (the upper end in the drawing in FIG. 12) in the sub-scanning direction.

  As in the case of the upper end processing, when the nozzle at the uppermost stream in the sub-scanning direction (hereinafter, this nozzle is referred to as “upper end nozzle”) is positioned at the bottom edge of the printing paper P, the lower end dot is recorded. In theory, an image can be recorded up to the bottom edge of the printing paper. However, in this embodiment, printing is performed on the lower end portion Pr of the printing paper P when the lower end of the printing paper P is positioned downstream of the upper end nozzle. Therefore, even when the landing position of the ink droplet on the printing paper is shifted, no margin is generated at the lower end of the printing paper.

  FIG. 13 is a side view showing the relationship between the print head 28 and the print paper P when the lower end portion Pr of the print paper P is printed. When printing the lower end portion Pr of the printing paper P, the lower end Pr of the printing paper P is positioned on the upstream groove portion 26f. The printing of the lower end portion Pr of the printing paper P is performed using the # 7 nozzle that is directly above the lower end portion Pr and the # 8 nozzle that is outside the lower end portion Pr of the printing paper P. For this reason, the printer 22 of the present embodiment can print an image without creating a margin at the lower end Pr of the printing paper P. Further, the printer 22 of this embodiment positions the printing paper P using the photo reflector 33 when printing is started. For this reason, as long as the sub-scan feed after the start of printing is performed accurately, the printing paper P can be accurately arranged with respect to the nozzles used in the lower end processing. Further, even when the printing paper position is shifted due to a sub-scan feed error or the like, since the nozzles # 7 and # 8 are located on the upstream groove 26f, the ink droplets land on the central portion 26c of the platen 26. There is nothing.

G. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

G1. Modification 1:
In the above embodiment, one detection unit is provided on the carriage 31. However, the detection unit can also be provided in another part of the printer 22. For example, a detection unit may be provided independently of the carriage 31 at a position further away from the platen than the space through which the carriage 31 passes in main scanning. With such an aspect, it is possible to detect the presence or absence of printing paper at the detection point without moving the carriage 31. Even when a dimensional error occurs in the position of the carriage in the main scanning, it is not affected. Furthermore, a plurality of detection units corresponding to different detection points can be provided. If a detection unit is provided on each of the left and right groove portions, this can be detected when the printing paper is displaced in any direction in the main scanning direction.

  In addition, the detection unit may be configured to move independently of the carriage 31 on the slide shaft 34. If the detection unit is moved so that the carriage and the detection unit do not interfere during printing, there will be no trouble in printing. With such an aspect, the height dimension of the printer can be reduced as compared with the aspect in which the detection unit is provided further away from the platen than the carriage 31 described above.

  FIG. 14 is a plan view showing the periphery of a platen 26 according to a modification. The detection unit may be provided further downstream in the sub-scanning direction than the position where the carriage 31 reciprocates in the main scanning. Even in such an aspect, by detecting the print medium by the detection unit (photoreflector 33a), the print medium can be accurately positioned to record dots, and an image can be formed on the record medium. However, in such an aspect, when the upper end portion of the printing paper is arranged on the groove and printing is performed without a margin to the upper end of the printing paper with the nozzle on the groove, the printing paper is directed upstream in the sub-scanning direction. It is necessary to feed the printing paper in the opposite direction.

  On the other hand, it is possible to adopt a mode in which the detection unit is provided further upstream in the sub-scanning direction than the position where the carriage 31 reciprocates in the main scanning. In such an embodiment, if printing is started after the detection unit detects the printing paper and the sub-scan feed is performed by a predetermined amount, the printing paper is placed so that the upper end of the printing medium comes to an arbitrary position. You can start printing. Therefore, after the printing paper is detected, the sub-scan can be performed so that the upper end of the printing paper comes on the groove, and the end printing can be performed with the nozzle on the groove from that state. As described above, if the detection unit is arranged downstream or upstream in the sub-scanning direction from the position where the carriage 31 reciprocates in the main scanning, the object of detecting the position of the printing medium with a simple structure is achieved. And the device can be made smaller.

G2. Modification 2:
In the above embodiment, both the upper end process and the lower end process are executed, but only one of them may be executed as necessary. Also, neither the upper end process nor the lower end process may be performed. The printing apparatus according to the present embodiment includes the upstream groove portion 26f and the downstream groove portion 26r on the upstream side and the downstream side in the sub-scanning direction of the platen 26, and includes the left groove portion 26a and the right groove portion 26b on the left and right. Any of these may be selectively provided. In such a case, it is preferable that printing of each end portion of the printing paper P is performed on the end portion where the corresponding groove portion is provided, and each nozzle is provided on the groove portion. Alternatively, the printing paper P may be accurately positioned on a platen that does not include a groove, and margins may be provided on four sides to print an image at an accurate position in the printing paper P.

G3. Modification 3:
In the above embodiment, a part of the configuration realized by hardware may be replaced with software, and conversely, a part of the configuration realized by software may be replaced by hardware. For example, the host computer 90 can execute part of the functions of the CPU 41 (FIG. 3).

  A computer program for realizing such a function is provided in a form recorded on a computer-readable recording medium such as a floppy disk or a CD-ROM. The host computer 90 reads the computer program from the recording medium and transfers it to the internal storage device or the external storage device. Or you may make it supply a computer program to the host computer 90 from a program supply apparatus via a communication path. When realizing the function of the computer program, the computer program stored in the internal storage device is executed by the microprocessor of the host computer 90. Further, the host computer 90 may directly execute the computer program recorded on the recording medium.

  In this specification, the host computer 90 is a concept including a hardware device and an operation system, and means a hardware device that operates under the control of the operation system. The computer program causes the host computer 90 to realize the functions of the above-described units. Note that some of the functions described above may be realized by an operation system instead of an application program.

  In the present invention, the “computer-readable recording medium” is not limited to a portable recording medium such as a flexible disk or a CD-ROM, but an internal storage device in a computer such as various RAMs and ROMs, An external storage device fixed to a computer such as a hard disk is also included.

FIG. 2 is a plan view schematically showing a structure around the platen of the ink jet printer according to the embodiment of the present invention. FIG. 3 is a block diagram illustrating a software configuration of the printing apparatus. FIG. 3 is a diagram illustrating a configuration of a mechanical part of the printing apparatus. Explanatory drawing which showed in detail the structure of the piezo element PE and the nozzle Nz. FIG. 4 is a plan view illustrating an example of an arrangement of nozzle units for each color in the print head unit 60. Explanatory drawing which shows the electrical structure of a photo reflector. FIG. 3 is a plan view showing the periphery of a platen 26. FIG. 3 is a plan view showing an arrangement of each part when the printing paper P is first arranged on the platen 26 in the ink jet printer. FIG. 4 is a side view showing the relationship between the print head and the printing paper P at the start of printing. FIG. 3 is a plan view showing the relationship between image data D and printing paper P. FIG. 3 is an explanatory diagram illustrating printing of left and right end portions of the printing paper P. The top view which shows the relationship between the upstream groove part 26f and the printing paper P at the time of printing the lower end part Pr of the printing paper P. FIG. FIG. 4 is a side view showing the relationship between the print head and the print paper P when printing the bottom end of the print paper. The top view which shows the periphery of the platen 26 of a modification. The side view which shows the periphery of the print head of the conventional printer.

12 ... Scanner 21 ... CRT
DESCRIPTION OF SYMBOLS 22 ... Printer 23 ... Paper feed motor 24 ... Carriage motor 25a, 25b ... Upstream paper feed roller 25c, 25d ... Downstream paper feed roller 25p, 25q ... Upstream paper feed roller 25r, 25s ... Downstream paper feed roller 26 ... Platen 26a ... Left side groove portion 26b ... Right side groove portion 26c ... Center portion 26d ... Connection portion 26f ... Upstream side groove portion 26o ... Platen 26r ... Downstream side groove portion 27 ... Absorbing member 28 ... Print head 28o ... Print head 29a, 29b ... Guide 31 ... Carriage 32 ... Operation panel 33, 33a ... Photo reflector 33d ... Light emitting diode 33t ... Phototransistor 34 ... Sliding shaft 36 ... Drive belt 38 ... Pulley 39 ... Position detection sensor 40 ... Control circuit 41 ... CPU
42 ... PROM
43 ... RAM
44 ... Drive buffer 45 ... PC interface 60 ... Print head unit 61-66 ... Ink ejection head 67 ... Introducing pipe 68 ... Ink passage 71 ... Cartridge 72 ... Color ink cartridge 90 ... Computer 91 ... Video driver 95 ... Application program 96 ... Printer driver 97 ... Resolution conversion module 98 ... Color correction module 99 ... Halftone module 100 ... Rasterizer

Claims (10)

A dot recording apparatus that records dots on the surface of a print medium using a dot recording head provided with a plurality of dot forming elements that eject ink droplets,
A main scanning drive unit that performs main scanning by driving the dot recording head with respect to the print medium;
A head driving unit that drives at least some of the plurality of dot forming elements during the main scanning to form dots; and
A sub-scan driving unit that performs sub-scanning by driving the print medium in a direction crossing the main scanning direction;
A detection unit for detecting the presence or absence of the print medium at a predetermined detection point;
A control unit for controlling the respective units,
The said recording part is a dot recording device provided in the position which does not cross the locus | trajectory of the ink droplet discharged from the said dot formation element in the said main scanning. The dot recording apparatus according to claim 1,
The controller is
A function of starting the sub-scanning of the print medium from a state where the print medium is not present at the detection point;
A function of stopping the sub-scan of the print medium at a predetermined sub-scan position with respect to the sub-scan direction when the detection unit detects the print medium;
A function of starting the main scanning while ejecting ink droplets from the dot forming element in a state where the print medium is at the predetermined sub-scanning position;
A dot recording apparatus comprising: The dot recording apparatus according to claim 1,
The detector is
A light emitting unit that emits light toward the predetermined detection point;
A light receiving unit that receives reflected light that is reflected when the light hits the print medium;
A dot recording apparatus. The dot recording apparatus according to claim 1,
The detection unit is a dot recording apparatus provided so as to be driven integrally with the dot recording head during the main scanning. The dot recording apparatus according to claim 4,
The position of the detection unit is set to a position in the vicinity of the dot forming element located at the downstream end in the sub scanning direction among the dot forming elements used for printing in the sub scanning direction. A dot recording device. The dot recording apparatus according to claim 1, further comprising:
A platen provided extending in the main scanning direction so as to face the dot forming element in at least a part of the main scanning path, and supporting the print medium;
The platen has a downstream groove provided extending in the main scanning direction at a position facing at least a dot forming element located at a downstream end in the sub-scanning direction among the plurality of dot forming elements. Have
The dot recording apparatus, wherein the detection point is a predetermined position within an opening of the downstream groove portion and within a range where the dot forming element exists in the sub-scanning direction. The dot recording apparatus according to claim 6, wherein:
The platen further includes a lateral groove portion that is provided in a range including at least an ink droplet landing range from the dot forming element in the sub-scanning direction, and is connected to the downstream groove portion,
The dot recording apparatus further includes a guide unit for positioning the print medium at a predetermined main scanning position in the main scanning direction during the sub-scanning,
The predetermined main scanning position is such that the printing medium is positioned within the main scanning stroke of the dot recording head with respect to the main scanning direction, and one side edge of the printing medium in the main scanning direction is A position located on the opening of the lateral groove,
The dot recording apparatus, wherein the detection point is a predetermined position of a connection portion between the side groove portion and the downstream groove portion. The dot recording apparatus according to claim 7, wherein
The side groove part is provided with a pair of a first side groove part and a second side groove part,
The first lateral groove and the second lateral groove are such that when the print medium is at the predetermined main scanning position, one side end of the print medium in the main scanning direction is the first side groove. A dot recording apparatus, wherein the dot recording apparatus is provided so as to be located on one side groove and the other side end is located on the second side groove. A dot recording head provided with a plurality of dot forming elements for ejecting ink droplets, and the presence or absence of the print medium at a predetermined detection point provided at a position that does not intersect the trajectory of the ink droplets of the dot forming elements during main scanning A dot recording method using a dot recording device that records dots on the surface of the print medium,
(A) starting sub-scanning, which is scanning for driving the recording medium in a direction crossing the main scanning direction, from a state where the print medium is not present at the detection point;
(B) stopping the sub-scanning of the print medium at a predetermined sub-scanning position with respect to the sub-scanning direction when the detection unit detects the print medium;
(C) starting the main scanning while ejecting ink droplets from the dot forming element in a state where the print medium is at the predetermined sub-scanning position;
A dot recording method comprising: A dot recording head provided with a plurality of dot forming elements for ejecting ink droplets, and the presence or absence of the print medium at a predetermined detection point provided at a position that does not intersect the trajectory of the ink droplets of the dot forming elements during main scanning And a computer-readable recording having recorded thereon a computer program for causing a computer to have a dot recording device for recording dots on the surface of the print medium. A medium,
A function of starting sub-scanning, which is scanning for driving the recording medium in a direction crossing the main scanning direction, from a state in which the print medium is not present at the detection point;
A function of stopping the sub-scan of the print medium at a predetermined sub-scan position with respect to the sub-scan direction when the detection unit detects the print medium;
A function of starting the main scanning while ejecting ink droplets from the dot forming element in a state where the print medium is at the predetermined sub-scanning position;
The computer-readable recording medium which has recorded the computer program for making the said computer implement | achieve.

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