JP2008068952A - Printing apparatus and printing method - Google Patents

Abstract

An end position of a printing object is accurately recognized regardless of a relative speed between an optical sensor and the printing object.
An optical sensor 45 for detecting a printing object P, a noise removing means 62 disposed on the output side of the optical sensor 45, an electrical time constant of the noise removing means 62, and an optical sensor 45. The original paper edge position of the print object P is calculated based on the relative speed of the optical sensor 45 and the print object P when the paper edge of the print object P is detected and the paper edge position of the print object P. The printing apparatus includes an end position calculation unit 70 that performs the above-described process.
[Selection] Figure 5

Description

  The present invention relates to a printing apparatus and a printing method.

  2. Description of the Related Art Conventionally, as a printing apparatus that performs printing on a print target, an ink jet printer that includes a print head that ejects ink onto the print target and a carriage on which the print head is mounted is known. In this type of printer, an optical sensor including a light emitting element and a light receiving element is widely used. For example, an optical sensor is mounted on the bottom surface of a carriage and is used to detect an end portion of a print object taken into the printer.

  For example, an optical sensor that outputs a low level signal when a print object is detected and outputs a high level signal when the print object is not detected is taken as one end of the print object. When detecting (the end of the carriage in the traveling direction start point side), it is determined whether or not the low level continues for a predetermined dimension ΔW after the sensor output changes from the high level to the low level. This dimension ΔW is set to be sufficiently longer than the width of the rib. When the low level continues for ΔW, it is determined that a print object is detected instead of a rib. As a result, the printing apparatus recognizes the carriage coordinates that have changed from the high level to the low level as the end of the print target (see, for example, Patent Document 1).

  In addition, as a printer equipped with an optical sensor, a printing unit that performs printing on a print object, a support unit that supports a print object that is printed by the printing unit, An optical system provided with a light emitting part that emits light and a light receiving part that receives light, and that generates a signal corresponding to the intensity of the light received by the light receiving part. A printer provided with a type sensor is also known (see, for example, Patent Document 2).

  In this printer, when printing, when the optical sensor moves relative to the support portion, a value obtained by sampling a signal generated by the optical sensor at a predetermined period; The print target is detected by comparing with a predetermined threshold value. When investigating the state of the support unit, the printer samples the signal generated by the optical sensor at a cycle different from a predetermined cycle when the optical sensor moves relative to the support unit. The predetermined threshold value is changed based on the value obtained by this sampling.

JP 2005-081750 A (Abstract) JP 2005-313603 A (abstract, etc.)

  The detection of the edge of the printing object by the optical sensor is useful for so-called borderless printing. When performing borderless printing, if the output voltage of the optical sensor is disturbed by electrical noise, the edge of the printing object cannot be accurately detected, and high-quality borderless printing cannot be performed. In particular, in the case of a large printer, since the FFC is long, it is easy to pick up noise. In addition, noise cannot be effectively removed if a low-cost optical sensor is used. Furthermore, as the printing apparatus is further downsized, the sheet metal becomes smaller, and the ground tends to become unstable. For this reason, noise removal means such as an RC circuit is usually mounted on the output side of the optical sensor to remove noise.

  When the noise removing means is mounted, the circuit constant is increased when the noise is large. However, increasing the circuit constant increases the electrical time constant of the noise removing means. For this reason, as the relative speed between the optical sensor and the printing object increases, the position of the end of the printing object cannot be detected accurately. Therefore, it is desired to reduce the error of the edge detection position due to the relative speed between the optical sensor and the printing object.

  The present invention has been made in order to meet the above demands, and provides a printing apparatus and a printing method for accurately recognizing the end position of a printing object regardless of the relative speed between the optical sensor and the printing object. The purpose is to provide.

  In order to achieve the above object, the present invention is a printing apparatus that performs printing on a printing object, an optical sensor for detecting the printing object, and noise removal arranged on the output side of the optical sensor. And the electrical time constant of the noise removing means, the relative speed between the optical sensor and the printing object when the optical sensor detects the edge of the printing object, and the edge position of the printing object. The printing apparatus includes an end position calculation unit that calculates an original end position of an object. For this reason, it is possible to accurately detect the end of the print object regardless of the relative speed of the print object and the optical sensor. Therefore, it is possible to suppress the occurrence of ink mist and prevent the printed image from being stained. In addition, an optimum circuit constant capable of removing noise can be selected even under conditions where noise is likely to occur, such as a large format printer with a long FFC. Accordingly, it is possible to prevent erroneous detection of the end portion of the printing object due to noise.

  In another aspect of the present invention, there is provided a relative speed variable means for changing the relative speed in the previous invention, a plurality of relative speeds, and a print object when an end of the print object is detected by an optical sensor at each relative speed. The printing apparatus further includes time constant calculating means for calculating an electric time constant based on the position of the end portion. Therefore, in practice, the electrical time constant can be obtained by changing the relative speed between the printing object and the optical sensor, and the electrical time constant can be used to detect the edge of the printing object during printing. it can. Therefore, it is possible to more accurately detect the end of the printing object during printing.

  Further, the present invention further includes a determination unit that determines whether or not noise is likely to increase based on the type of the printing object in each of the previous inventions, and that the determination unit is likely to increase noise. When the determination is made, the end position calculation means is a printing apparatus that calculates the original end position of the print object. For this reason, when the print object is large and the FFC is long and noise is likely to occur, when the reflectance of the print object is low and its end is relatively difficult to detect, the end position is calculated. In the case where printing is performed on a printing object with low noise, the end position can be not calculated.

  Further, the present invention further includes a determination unit that determines whether or not noise is likely to increase based on the type of the printing object in each of the previous inventions, and that the determination unit is likely to increase noise. When the determination is made, the time constant calculation means is a printing apparatus that calculates the electrical time constant. For this reason, when the print object is large and the FFC is long and noise is likely to occur, when the reflectance of the print object is low and its end is relatively difficult to detect, the end position is calculated. In the case where the electrical time constant is calculated and printing is performed on a print object with low noise, the electrical time constant can be prevented from being calculated.

  Another aspect of the present invention is a printing apparatus in which the optical sensor in each of the previous inventions is mounted on a carriage that is scanned in the width direction of a print object. For this reason, in particular, the end of the printing object in the width direction (that is, the main scanning direction) can be accurately detected by scanning the carriage.

  Another aspect of the present invention is a printing method for printing on a printing object, an edge detection step of detecting an edge of the printing object by an optical sensor, and removing noise from the output of the optical sensor. The original end of the print object based on the electrical time constant of the noise removal means, the relative speed between the optical sensor and the print object when the end of the print object is detected, and the end position of the print object The printing method includes an end position calculating step for calculating the position. For this reason, by using the printing method, it is possible to accurately detect the end portion of the printing object regardless of the relative speed of the printing object and the optical sensor. Therefore, it is possible to suppress the occurrence of ink mist and prevent the printed image from being stained. In addition, an optimum circuit constant capable of removing noise can be selected even under conditions where noise is likely to occur, such as a large format printer with a long FFC. Accordingly, it is possible to prevent erroneous detection of the end portion of the printing object due to noise.

  Another aspect of the present invention is a relative speed setting step for setting a relative speed in the previous invention, a plurality of relative speeds, and an object to be printed when an end of the print object is detected by an optical sensor at each relative speed. The printing method further includes a time constant calculating step of calculating an electric time constant based on the end position of the object. For this reason, by using the printing method, an electrical time constant is actually obtained by changing the relative speed between the printing object and the optical sensor, and the edge of the printing object is detected during printing. An electrical time constant can be used. Therefore, it is possible to more accurately detect the end of the printing object during printing.

  Hereinafter, preferred embodiments of a printing apparatus and a printing method according to the present invention will be described with reference to the drawings.

(1) Schematic Configuration of Printing Apparatus FIG. 1 is a perspective view showing a schematic configuration of a printing apparatus 1 according to an embodiment of the present invention. FIG. 2 is a schematic side view showing a schematic configuration of a portion related to paper feeding of the printing apparatus 1 shown in FIG. FIG. 3 is a schematic configuration diagram schematically showing a detection mechanism of the carriage 3 shown in FIG. 1 and the PF drive roller 6 shown in FIG. FIG. 4 is a front view showing a schematic configuration of the optical sensor 45 shown in FIG.

  The printing apparatus 1 according to the present embodiment is an ink jet printer that performs printing by ejecting liquid ink onto a printing paper P that is one form of a printing object. As shown in FIGS. 1 to 3, the printing apparatus 1 includes a carriage 3 on which a print head 2 that ejects ink is mounted, a carriage motor (CR motor) 4 that drives the carriage 3 in the main scanning direction MS, and printing. The paper feed motor (PF motor) 5 that transports the paper P in the sub-scanning direction SS, the PF drive roller 6 connected to the PF motor 5, and the ink ejection surface (lower surface in FIG. 2) 2a of the print head 2 face each other. And the main body chassis 8 on which these configurations are mounted. Note that the printing paper P in this embodiment includes plain paper used for normal document printing, glossy paper used for photo printing, thick paper thicker than plain paper and photographic paper, etc., as well as stickers and OHP. A transparent film such as a sheet is also included.

  Further, as shown in FIG. 2, the printing apparatus 1 has a hopper 11 on which the printing paper P before printing is placed, and a supply for taking the printing paper P placed on the hopper 11 into the printing apparatus 1. A paper roller 12 and a separation pad 13, a paper detection device 14 for detecting the passage of the printing paper P taken into the printing device 1 from the hopper 11, and a discharge for discharging the printing paper P from the printing device 1. And a paper drive roller 15.

  The carriage 3 is configured to be transportable in the main scanning direction MS by a guide shaft 17 supported by a support frame 16 fixed to the main body chassis 8 and a timing belt 18. That is, a part of the timing belt 18 is fixed to the carriage 3 (see FIG. 2), and the pulley 19 attached to the output shaft of the CR motor 4 and the pulley 20 attached rotatably to the support frame 16 It is arrange | positioned so that it may have fixed tension in the state hung over. The guide shaft 17 slidably holds the carriage 3 so as to guide the carriage 3 in the main scanning direction MS. In addition to the print head 2, an ink cartridge 21 that stores various inks supplied to the print head 2 is mounted on the carriage 3.

  The print head 2 is provided with a plurality of nozzles (not shown). The print head 2 is provided with a piezoelectric element (not shown) that is one of electrostrictive elements and has excellent responsiveness so as to correspond to each nozzle, for example. Specifically, the piezoelectric element is disposed at a position in contact with a wall surface that forms an ink passage (not shown). When the wall surface is pushed by the operation of the piezo element, the print head 2 ejects ink from the nozzles disposed at the end of the ink passage. Specifically, the print head 2 ejects ink from the ink ejection surface 2a.

  The paper feed roller 12 is connected to the PF motor 5 through a gear (not shown) and is driven by the PF motor 5. As shown in FIG. 2, the hopper 11 is a plate-like member on which the printing paper P can be placed, and can swing around a rotation shaft 22 provided on the upper portion by a cam mechanism (not shown). ing. The lower end portion of the hopper 11 is elastically pressed against the paper feed roller 12 by the cam mechanism and is separated from the paper feed roller 12. The separation pad 13 is formed of a member having a high friction coefficient, and is disposed at a position facing the paper feed roller 12. The paper feed roller 12 is not necessarily connected to the PF motor 5, and a driving motor for driving the paper feed roller 12 may be provided separately.

  When the paper feed roller 12 rotates, the surface of the paper feed roller 12 and the separation pad 13 are pressed against each other. Therefore, when the paper feeding roller 12 rotates, the uppermost printing paper P among the printing paper P placed on the hopper 11 passes through the pressure contact portion between the surface of the paper feeding roller 12 and the separation pad 13. Although it is sent to the paper discharge side, the printing paper P placed on the second and subsequent pages from the top is prevented from being conveyed to the paper discharge side by the separation pad 13.

  The PF drive roller 6 is connected to the PF motor 5 directly or via a gear not shown. As shown in FIG. 2, the printing apparatus 1 is provided with a PF driven roller 23 that conveys the printing paper P together with the PF drive roller 6. The PF driven roller 23 is rotatably held on the paper discharge side of the driven roller holder 24 configured to be swingable about the rotation shaft 25. The driven roller holder 24 is urged counterclockwise by an unillustrated spring so that the PF driven roller 23 always receives the urging force toward the PF drive roller 6. When the PF driving roller 6 is driven, the PF driven roller 23 is rotated together with the PF driving roller 6.

  As shown in FIG. 2, the paper detection device 14 includes a detection lever 26 and an optical sensor 27, and is provided in the vicinity of the driven roller holder 24. The detection lever 26 is rotatable about the rotation shaft 28. When the printing paper P passes through the lower side of the detection lever 26 from the passage state of the printing paper P shown in FIG. 2, the detection lever 26 rotates counterclockwise. When the detection lever 26 rotates, light from the light emitting element (not shown) of the optical sensor 27 toward the light receiving element (not shown) is blocked, and the end of passage of the printing paper P can be detected.

  The paper discharge drive roller 15 is disposed on the paper discharge side of the printing apparatus 1 and is connected to the PF motor 5 via a gear (not shown). As shown in FIG. 2, the printing apparatus 1 is provided with a paper discharge driven roller 29 that discharges the printing paper P together with the paper discharge driving roller 15. Similarly to the PF driven roller 23, the paper discharge driven roller 29 is always urged toward the paper discharge drive roller 15 by a spring (not shown). When the paper discharge driving roller 15 is driven, the paper discharge driven roller 29 is rotated together with the paper discharge driving roller 15.

  Further, as shown in FIGS. 2 and 3, the printing apparatus 1 includes a linear scale 31 and an optical sensor as a position detection device for detecting the position of the carriage 3 in the main scanning direction MS, detecting the speed of the carriage 3, and the like. A linear encoder 33 having 32 is provided. Further, as shown in FIG. 3, the printing apparatus 1 detects the position of the printing paper P in the sub-scanning direction SS, detects the conveyance speed of the printing paper P, and the like (specifically, detects and rotates the rotational position of the PF driving roller 6). A rotary encoder 36 having a rotary scale 34 and an optical sensor 35 is provided as a position detection device for performing speed detection and the like. As shown in FIG. 3, the position detection signals output from the linear encoder 33 and the rotary encoder 36 are input to a control unit 37 that performs various controls of the printing apparatus 1, and various controls of the printing apparatus 1 are performed. Is called. In FIG. 1, the linear scale 31 and the like are not shown for convenience.

  As shown in FIGS. 2 and 3, the optical sensor 32 constituting the linear encoder 33 includes a light emitting element 41 and a light receiving element 42. The optical sensor 32 is fixed to the back surface of the carriage 3 (the back surface in FIG. 1). The linear scale 31 is formed in a long shape (elongated linear shape) from a transparent resin thin plate or the like. The linear scale 31 is attached to the support frame 16 in parallel with the main scanning direction MS. Further, the linear scale 31 has a light transmitting portion (not shown) that transmits light from the light emitting element 41 of the optical sensor 32 and a light shielding portion (not shown) that blocks light from the light emitting element 41. It is formed alternately along the direction. When the carriage 3 moves, the linear scale 31 relatively moves between the light emitting element 41 and the light receiving element 42 of the optical sensor 32. As the linear scale 31 moves relatively, the optical sensor 32 outputs a position detection signal at a cycle corresponding to the moving speed of the carriage 3.

  As shown in FIG. 3, the optical sensor 35 constituting the rotary encoder 36 includes a light emitting element 43 and a light receiving element 44, and is fixed to the main chassis 8 or the like via a bracket (not shown). The rotary scale 34 is made of a transparent resin thin plate or the like and is formed in a disk shape. The rotary scale 34 of this embodiment is attached to the PF drive roller 6 so as to rotate integrally with the PF drive roller 6. That is, when the PF drive roller 6 makes one revolution, the rotary scale 34 also makes one revolution. The rotary scale 34 has a translucent part (not shown) that transmits light from the light emitting element 43 of the optical sensor 35 and a light shielding part (not shown) that blocks light from the light emitting element 43. It is formed alternately along the direction. When the PF drive roller 6 rotates, the rotary scale 34 rotates relatively between the light emitting element 43 and the light receiving element 44 of the optical sensor 35. The optical sensor 35 outputs a position detection signal at a period corresponding to the rotational speed of the PF drive roller 6 along with the relative rotation of the rotary scale 34.

  Further, as shown in FIGS. 2 to 4, the printing apparatus 1 detects the edge of the printing paper P or the like in the main scanning direction MS (movement direction of the carriage 3), and the printing paper P or the like in the sub-scanning direction SS. An optical sensor 45 is provided for detecting the end portions (that is, the front end portion and the rear end portion of the printing paper P or the like). The optical sensor 45 is fixed to the carriage 3 as shown in FIG. Specifically, the optical sensor 45 is fixed on the lower surface side of the carriage 3 and on the upstream side (right side in FIG. 2) of the print head 2 in the sub-scanning direction SS. As shown in FIG. 3, the optical sensor 45 is fixed to the left end side of the carriage 3 in the main scanning direction MS.

  As shown in FIG. 4, the optical sensor 45 includes a light emitting element 46 that emits light toward the platen 7 or the printing paper P in order to detect an end portion of the printing paper P, and the like. This is a reflection type optical sensor including a light receiving element 47 on which light emitted and reflected by the platen 7 or the printing paper P is incident. In the optical sensor 45, the platen 7 or printing is performed from the light emitting element 46 with the movement of the carriage 3 in the main scanning direction MS or while conveying the printing paper P to the sub-scanning method SS with the carriage 3 stopped. Light is emitted toward the paper P, and the light reflected by the platen 7 or the printing paper P enters the light receiving element 47. The optical sensor 45 is electrically connected to the control unit 37 as shown in FIG.

(2) Schematic Configuration of Optical Sensor and Control Unit FIG. 5 is a diagram showing a schematic configuration of the optical sensor 45 and the control unit 37 shown in FIG. In FIG. 5, only the configuration in the control unit 37 related to the optical sensor 45 is shown.

  As described above, in the present embodiment, the optical sensor 45 is a reflective photointerrupter including the light emitting element 46 and the light receiving element 47. For example, as shown in FIG. 5, the optical sensor 45 includes a light emitting diode as the light emitting element 46 and a phototransistor as the light receiving element 47. In the optical sensor 45, a resistor 48 is disposed on the current input side to the light emitting element 46.

  The optical sensor 45 outputs an output signal corresponding to the amount of light received by the light receiving element 47. That is, the optical sensor 45 outputs an output signal that is at a low level when the printing paper P is detected and is at a high level when the printing paper P is not detected. The output signal becomes low when the light receiving element 47 receives light emitted from the light emitting element 46 and reflected by the printing paper P, and the light receiving element 47 receives light emitted from the light emitting element 46 and reflected by the platen 7. When receiving light, the level is high. In the present embodiment, the platen 7 is formed of a member such as black having a low light reflectance. The printing paper P having a higher light reflectance than that of the platen 7 reflects more light than the platen 7. For this reason, when the amount of light received by the light receiving element 47 is large, the output signal is at a low level. On the other hand, when the amount of light received by the light receiving element 47 is small, the output signal is at a high level. Further, when the amount of light received by the light receiving element 47 increases (that is, when the value of the current flowing through the light receiving element 47 increases), the level of the output signal decreases. When the amount of light received by the light receiving element 47 decreases (that is, when the current value flowing through the light receiving element 47 decreases), the level of the output signal increases.

  As shown in FIG. 5, the control unit 37 has a configuration related to the optical sensor 45, and supplies a current to the light emission intensity adjusting unit 50 for adjusting the light emission intensity of the light emitting element 46, and the light emitting element 46 and the light receiving element 47. An internal power supply 52 as a power supply to be supplied, a resistor 53 connected between the internal power supply 52 as a power supply for supplying current to the light emitting element 46 and the light emission intensity adjusting unit 50, and an internal for supplying current to the light receiving element 47 A resistor 55 connected between the power source 52 and the light receiving element 47, an end detection unit 59 for detecting the end of the printing paper P, and an output disposed between the light receiving element 47 and the end detection unit 59. RC circuit 62 which is noise removing means for removing the side noise.

  The light emission intensity adjusting unit 50 includes a transistor 60 disposed between the resistor 53 and the light emitting element 46, and a D / A converter 61 connected to the base terminal of the transistor 60. The transistor 60 is a PNP transistor, and a light emitting element 46 is connected to the collector terminal side, and an internal power supply 52 is connected to the emitter terminal side via a resistor 53. The D / A converter 61 adjusts the light emission intensity of the light emitting element 46 by increasing or decreasing the current flowing from the emitter terminal to the collector terminal of the transistor 60, that is, the current supplied from the internal power supply 52 to the light emitting element 46 with a predetermined resolution. To do.

  The end detection unit 59 includes an A / D converter 65 and an end determination unit 66. An output signal from the optical sensor 45 is input to the A / D converter 65. The A / D converter 65 has a function of converting the output voltage of the optical sensor 45 into a digital value. For example, in the case of an 8-bit A / D converter 65, 3.3V is a digital value 255 and 0.0V is a digital value 0. The edge determination unit 66 determines the edge of the printing paper P based on the digital value output from the A / D converter 65.

The RC circuit 62 includes a resistor 63 that is connected between the light receiving element 47 and the A / D converter 65, and a capacitor 64 that is branched from the resistor 63 and the A / D converter 65. Yes. The capacitor 64 is grounded. The RC circuit 62 is a low-pass filter composed of a resistor 63 and a capacitor 64, and has a function of passing only a signal having a certain frequency or less. With this function, noise included in the output signal of the optical sensor 45 can be removed.

  Further, the control unit 37 includes an end position calculation unit 70 as an end position calculation unit that calculates the original end position of the printing paper P, and a time constant calculation unit that calculates an electrical time constant of the RC circuit 62. As a time constant calculation unit 71, an end position calculation unit 70, and a time constant calculation unit 71, and information such as an end position and a time constant calculated by the end position calculation unit 70 and the time constant calculation unit 71. , A storage unit 72 as a storage unit that stores information, a determination unit 73 as a determination unit that determines whether noise is likely to increase based on the type of the printing paper P, the optical sensor 45, and the printing paper And a relative speed variable unit 74 as a relative speed variable means for changing the relative speed with respect to P. The storage unit 72 stores information about the printing paper P that is likely to be noisy.

  The control unit 37 is connected to a printing paper information receiving unit 75 that receives information about the printing paper P. The printing paper information receiving unit 75 receives information such as the size (A3, B4, etc.), type (glossy paper, plain paper, etc.) or color of the printing paper P input by the user. However, the printing paper information receiving unit 75 may be a unit that receives information such as the size, type, or color of the printing paper P that is automatically recognized through a sensor or the like.

  The edge position calculation unit 70 detects the electrical time constant t of the RC circuit 62, the relative speed between the optical sensor 45 and the printing paper P when the optical sensor 45 detects the paper edge of the printing paper P, and the printing paper P. Based on the paper edge position, the original paper edge position of the printing paper P is calculated. The relative speeds of the optical sensor 45 and the printing paper P in the main scanning direction MS and the sub scanning direction SS are received from the relative speed variable unit 74. However, the relative speed in the main scanning direction MS may be an actually measured speed based on a detection signal from the optical sensor 32. Similarly, the relative speed in the sub scanning direction SS may be an actually measured speed based on a detection signal from the optical sensor 35. The edge position calculation unit 70 recognizes each sheet edge position of the printing paper P in the main scanning direction MS and the sub scanning direction SS based on the determination result of the edge determination unit 66. Further, the end position calculation unit 70 receives the electrical time constant t of the RC circuit 62 from the storage unit 72.

  When the relative speed between the optical sensor 45 and the printing paper P is changed, the time constant calculation unit 71 prints when the relative speed and the edge of the printing paper P are detected by the optical sensor 45 at each relative speed. Based on the end position of the paper P, the electrical time constant t of the RC circuit 62 is calculated. The relative speed between the optical sensor 45 and the printing paper P is received from the relative speed variable unit 74. However, as described above, the relative speed may be the actually measured speed. Further, the paper edge position of the printing paper P when the optical sensor 45 detects the paper edge of the printing paper P is recognized based on the determination result of the edge determination unit 66 as in the case of the edge position calculation unit 70. Is done. The time constant calculation unit 71 stores the electrical time constant t obtained by the calculation in the storage unit 72.

  The determination unit 73 determines whether noise is likely to increase based on information indicating the type of the print paper P from the print paper information reception unit 75. At the time of the determination, the determination unit 73 obtains information of the printing paper P that is registered in advance and is likely to generate noise from the storage unit 72, and receives the information received from the printing paper information reception unit 75. Match. The edge position calculation unit 70 and the time constant calculation unit 71 receive the result of the determination unit 73, and do not calculate the sheet edge position and the time constant, respectively, in the case of the printing paper P in which noise is difficult to increase. On the other hand, the edge position calculation unit 70 and the time constant calculation unit 71 calculate the sheet edge position and the time constant, respectively, in the case of the printing paper P in which noise tends to increase.

  The end determination unit 66, the end position calculation unit 70, the time constant calculation unit 71, the determination unit 73, and the relative speed variable unit 74 are realized by a calculation unit such as a CPU. The storage unit 72 is realized by a ROM, a RAM, a nonvolatile memory, or the like.

(3) Paper Edge Detection Method for Printing Paper P FIG. 6 is a graph for explaining a phenomenon in which the detection of the paper edge position of the printing paper P is deviated and recognized depending on the speed of the carriage 3. The horizontal axis indicates the moving distance of the carriage 3 from the home position. The vertical axis represents the output value of the optical sensor 45. Also, the vicinity of the paper edge of the printing paper P is shown below the horizontal axis.

  When the moving speed of the carriage 3 is not taken into consideration, the relationship between the moving distance of the carriage 3 and the output voltage of the optical sensor 45 is an output voltage curve (curve A) indicated by a dotted line. That is, the moving distance of the carriage 3 at which the output voltage is equal to or less than the determination threshold matches the position of the paper edge of the printing paper P.

  However, when the speed of the carriage 3 is V_vs (high speed), the output voltage curve (curve C) shown by the solid line on the right side of FIG. 6 is obtained. As is apparent from the curve C, the position (POS_vs) at which the output voltage of the optical sensor 45 is equal to or less than the determination threshold and is recognized as the paper edge is shifted by POS_rc from the original paper edge position (POS_vs−POS_rc). On the other hand, when the speed of the carriage 3 is Va (low speed), an output voltage curve (curve B) shown by a solid line in the center of FIG. 6 is obtained. As is apparent from the curve B, the position where the output voltage of the optical sensor 45 is equal to or lower than the determination threshold value and is recognized as the paper edge is shifted from the original paper edge position (POS_vs-POS_rc), but the carriage 3 The amount of deviation is smaller than when V_vs (high speed) is set. That is, as the speed of the carriage 3 is increased, the detection position of the paper edge is greatly shifted from the original paper edge position. This is because when the circuit constant is increased for noise removal, the electrical time constant t increases, and the deviation of the paper edge detection increases as the speed of the carriage 3 increases.

  In order to reduce the deviation amount of the paper edge depending on the speed of the carriage 3 and accurately recognize the original paper edge regardless of the speed of the carriage 3, the printing apparatus 1 performs the following processing. Yes.

  FIG. 7 is a flowchart showing a flow of processing for calculating the electrical time constant t of the RC circuit 62.

  First, the determination unit 73 receives information about the printing paper P from the printing paper information reception unit 75, and determines whether the printing paper P is a paper type that increases noise (step S101). If the result of the determination in step S101 is that the printing paper P is not a paper type that increases noise, the processing ends because the necessity of performing the electrical time constant t calculation processing is low.

  On the other hand, if the result of the determination in step S101 is that the printing paper P is a paper type that increases noise, the relative speed variable unit 74 rotates necessary to drive the carriage 3 at a low speed (for example, 5 cps). The CR motor 4 is driven at a speed (step S102: relative speed setting step). Next, based on the output voltage of the optical sensor 45, the edge determination unit 66 detects the paper edge of the printing paper P and determines the paper edge position (step S103). Next, the time constant calculation unit 71 acquires the speed of the carriage 3 and the paper end position at the time of paper end detection (step S104).

  Next, the relative speed variable means 74 drives the CR motor 4 at a rotational speed necessary for driving the carriage 3 at a high speed (for example, 280 cps) (step S105: relative speed setting step). Next, based on the output voltage of the optical sensor 45, the edge determination unit 66 detects the paper edge of the printing paper P and determines the paper edge position (step S106). Next, the time constant calculation unit 71 acquires the speed of the carriage 3 and the paper end position at the time of paper end detection (step S107).

  Next, the time constant calculation unit 71 reads the calculation formula shown in Formula 1 from the storage unit 72 (step S108). T in Formula 1 is an electrical time constant to be obtained. POS_hv is the paper edge position obtained under the condition that the speed of the carriage 3 is high. POS_lv is a paper edge position obtained under the condition that the speed of the carriage 3 is low. V_hv and V_lv are the high speed and low speed of the carriage 3, respectively. A is a conversion coefficient.

      t = (POS_hv−POS_lv) / A (V_hv−V_lv) Equation 1

  Next, the time constant calculating unit 71 inputs the speeds of the two carriages 3 and the two paper end positions acquired in Step S104 and Step S107 into the read calculation formula, and calculates the electrical time constant t ( Step S109: Time constant calculation step). Next, the time constant calculation unit 71 stores the electrical time constant t obtained in step S109 in the storage unit 72 (step S110). With this flow, the time constant calculation process ends.

  When detecting the paper edge of the printing paper P in the sub-scanning direction SS, the optical sensor is fixed and the printing paper P is moved to recognize the paper edge position. In such a case, a curve similar to the output voltage curve shown in FIG. 6 is obtained by taking the movement distance of the printing paper P on the horizontal axis and the output voltage of the optical sensor on the vertical axis in FIG. That is, as the speed of the printing paper P increases, the error in detecting the position of the edge of the printing paper P increases. The error correction method will be described below.

  FIG. 8 is a flowchart showing a flow of processing for calculating the electrical time constant t of the RC circuit arranged on the output side of the optical sensor 27 that can move the printing paper P in the sub-scanning direction SS and detect the paper edge. It is.

  First, the determination unit 73 receives the information of the print paper P from the print paper information reception unit 75, and determines whether or not the print paper P is a paper type that increases noise (step S201). If the result of determination in step S201 is that the printing paper P is not a paper type that increases noise, the processing ends because the necessity of performing the electrical time constant t calculation processing is low.

  On the other hand, if the result of determination in step S201 is that the printing paper P is a paper type that increases noise, the relative speed variable unit 74 performs PF at the rotational speed necessary for driving the printing paper P at low speed. The motor 5 is driven (step S202: relative speed setting step). Next, based on the output voltage of the optical sensor 27, the edge determination unit 66 detects the paper edge of the printing paper P and determines the paper edge position (step S203). Next, the time constant calculation unit 71 acquires the speed of the printing paper P and the paper edge position at the time of paper edge detection (step S204).

  Next, the relative speed variable unit 74 drives the PF motor 5 at a rotational speed necessary for driving the printing paper P at a high speed (step S205: relative speed setting step). Next, based on the output voltage of the optical sensor 27, the edge determination unit 66 detects the paper edge of the printing paper P and determines the paper edge position (step S206). Next, the time constant calculation unit 71 acquires the speed of the printing paper P and the paper edge position at the time of paper edge detection (step S207).

  Next, the time constant calculation unit 71 reads out the calculation formula shown in Formula 1 from the storage unit 72 (step S208). Next, the time constant calculation unit 71 inputs the speeds of the two printing papers P and the two paper edge positions acquired in Step S204 and Step S207 to the read calculation formula, and calculates the electrical time constant t. (Step S209: Time constant calculation step). Next, the time constant calculation unit 71 stores the electrical time constant t obtained in step S209 in the storage unit 72 (step S210). With this flow, the time constant calculation process ends.

  Next, a method for calculating the paper edge position from the electrical time constant t stored in the storage unit 72 will be described.

  FIG. 9 is a flowchart showing a flow of processing for calculating the paper edge position in the main scanning direction MS using the electrical time constant t.

  First, the determination unit 73 receives information about the print paper P from the print paper information reception unit 75, and determines whether or not the print paper P is a paper type that increases noise (step S301). If the result of the determination in step S301 is that the printing paper P is not a paper type that increases noise, the processing ends because the necessity of performing the paper edge position calculation processing is low.

  On the other hand, if the result of the determination in step S301 is that the printing paper P is a paper type that increases noise, the relative speed variable unit 74 needs a rotational speed required to drive the carriage 3 at a predetermined speed (V_vs). The CR motor 4 is driven at (step S302). Next, based on the output voltage of the optical sensor 45, the edge determination unit 66 detects the paper edge of the printing paper P and determines the paper edge position (step S303: edge detection step). Next, the edge position calculation unit 70 acquires the output voltage of the optical sensor 45 and the paper edge position at the time of paper edge detection (step S304).

  Next, the end position calculation unit 70 reads the calculation formula and the electrical time constant t shown in Formula 2 from the storage unit 72 (Step S305). (POS_vs−POS_rc) in Equation 2 is the paper edge position to be obtained. POS_vs is the paper edge position at which the paper edge is recognized at a predetermined speed (V_vs). A and t are a conversion factor and an electrical time constant, respectively.

      POS_vs−POS_rc = POS_vs−A × V_vs × t Equation 2

  Next, the end position calculation unit 70 inputs the electrical time constant t read from the storage unit 72 in addition to the output voltage and the paper end position acquired in step S304 to the read calculation formula. The position is calculated (step S306: end position calculation step). With this flow, the paper edge position calculation process ends.

  FIG. 10 is a flowchart showing the flow of processing for calculating the paper edge position in the sub-scanning direction SS using the electrical time constant t.

  First, the determination unit 73 receives information about the print paper P from the print paper information reception unit 75, and determines whether or not the print paper P is a paper type that increases noise (step S401). If the result of determination in step S401 is that the printing paper P is not a paper type that increases noise, it is less necessary to perform paper edge position calculation processing, and the processing ends.

  On the other hand, if the result of the determination in step S401 is that the printing paper P is a paper type that increases noise, the relative speed variable unit 74 rotates necessary to drive the printing paper P at a predetermined speed (V_vs). The PF motor 5 is driven at the speed (step S402). Next, based on the output voltage of the optical sensor 27, the edge determination unit 66 detects the paper edge of the printing paper P and determines the paper edge position (step S403: edge detection step). Next, the edge position calculation unit 70 acquires the output voltage of the optical sensor 27 and the paper edge position at the time of paper edge detection (step S404).

  Next, the end position calculation unit 70 reads out the calculation formula and the electrical time constant t shown in Formula 2 above from the storage unit 72 (Step S405). Next, the edge position calculation unit 70 inputs the electrical time constant t read from the storage unit 72 in addition to the output voltage and the paper edge position acquired in step S404 to the read calculation formula. The position is calculated (step S406: end position calculation step). With this flow, the paper edge position calculation process ends.

  FIG. 11 is a diagram illustrating a print area (P1) recognized without correcting the paper edge position and a print area (P2) after the paper edge position is corrected when performing borderless printing.

  A printing area P1 indicated by a dotted line is an area that is inside the printing paper P by L1 on both sides in the main scanning direction MS and that is inside by L2 on both sides in the sub-scanning direction SS. On the other hand, the printing area P2 is an area that almost overlaps the printing paper P, and there is no error in both the main scanning direction MS and the sub-scanning direction SS. Therefore, when performing borderless printing, the printing area of the printing paper P is accurately recognized by performing the paper edge position correction processing as shown in the above-described flowchart.

(4) Main Effects of the Present Embodiment The printing apparatus 1 according to the present embodiment includes the optical sensor 45, the RC circuit 62 disposed on the output side of the optical sensor 45, and the electric power of the RC circuit 62. The end of calculating the original paper end position of the printing paper P based on the target time constant t and the speed of the carriage 3 and the paper edge position of the printing paper P when the optical sensor 45 detects the paper edge of the printing paper P. A part position calculation unit 70. Therefore, it is possible to accurately detect the paper edge of the printing paper P in the main scanning direction MS regardless of the speed of the carriage 3. Further, the end position calculation unit 70 detects the electrical time constant t of the RC circuit disposed on the output side of the optical sensor 27, and the optical sensor 27 detects the paper end of the printing paper P in the sub-scanning direction SS. Based on the speed of the printing paper P and the paper edge position of the printing paper P, the original paper edge position of the printing paper P in the sub-scanning direction SS can be calculated. Therefore, it is possible to suppress the occurrence of ink mist and prevent the printed image from being stained. In addition, an optimum circuit constant capable of removing noise can be selected even under conditions where noise is likely to occur, such as a large format printer with a long FFC. Therefore, it is possible to prevent erroneous detection of the edge of the printing paper P due to noise.

  Further, the printing apparatus 1 according to the present embodiment includes a relative speed variable unit 74 that changes the speed of the carriage 3, a plurality of speeds of the carriage 3, and a main scanning direction MS of the printing paper P by the optical sensor 45 at each speed. And a time constant calculator 71 for calculating an electrical time constant t based on the paper edge position of the printing paper P when the paper edge is detected. Therefore, in practice, the electric time constant t can be obtained by changing the speed of the carriage 3, and the electric time constant t can be used for detecting the end of the printing paper P during printing. Therefore, the end of the printing paper P in the main scanning direction MS can be detected more accurately during printing. In addition, the relative speed variable unit 74 in the printing apparatus 1 changes the speed of the printing paper P in the sub-scanning direction SS, so that the time constant calculation unit 71 has a plurality of speeds of the printing paper P and the optical sensor 45 at each speed. Thus, the electrical time constant t is calculated based on the paper edge position of the printing paper P when the paper edge of the printing paper P in the sub-scanning direction SS is detected. Therefore, in practice, the electrical time constant t can be obtained by changing the speed of the printing paper P, and the electrical time constant t can be used for detecting the end of the printing paper P during printing. Therefore, the end of the printing paper P in the sub-scanning direction SS can be detected more accurately during printing.

  The printing apparatus 1 according to the present embodiment further includes a determination unit 73 that determines whether noise is likely to increase based on the type of the printing paper P, and the determination unit 73 increases the noise. If it is determined that it is easy, the edge position calculation unit 70 calculates the original paper edge position of the printing paper P. For this reason, when the print paper P is large and the FFC is long and noise is likely to occur, or when the print paper P has a low reflectance and it is relatively difficult to detect the paper edge, the paper edge position is calculated. When printing is performed on the printing paper P with low noise, it is possible not to calculate the paper edge position.

  In the printing apparatus 1 according to the present embodiment, when the determination unit 73 determines that noise is likely to increase based on the type of the printing paper P, the time constant calculation unit 71 calculates the electrical time constant t. is doing. For this reason, when the print paper P is large and the FFC is long and noise is likely to occur, or when the print paper P has a low reflectance and its edge is relatively difficult to detect, the paper edge position is calculated. When the electrical time constant t is calculated and printing is performed on the printing paper P with low noise, the electrical time constant t can be prevented from being calculated.

  In the printing apparatus 1 according to the present embodiment, the optical sensor 45 is mounted on the carriage 3 that is scanned in the main scanning direction (width direction) of the printing paper P. Therefore, in particular, the paper edge in the width direction of the printing paper P can be accurately detected by scanning the carriage 3.

  In the printing method according to the present embodiment, the edge detection step of detecting the paper edge of the printing paper P in the main scanning direction MS by the optical sensor 45, the electrical time constant t of the RC circuit 62, the printing paper P An edge position calculating step of calculating the original paper edge position of the printing paper P in the main scanning direction MS based on the speed of the carriage 3 and the paper edge position of the printing paper P when the paper edge is detected. Yes. Therefore, it is possible to accurately detect the paper edge of the printing paper P in the main scanning direction MS regardless of the speed of the carriage 3. Furthermore, in the printing method according to the present embodiment, the optical sensor 27 detects the edge of the printing paper P in the sub-scanning direction SS, and the RC circuit is arranged on the output side of the optical sensor 27. The paper edge position in the original sub-scanning direction SS of the printing paper P is determined based on the electrical time constant t, the speed of the printing paper P when the paper edge of the printing paper P is detected, and the paper edge position of the printing paper P. And an end position calculating step of calculating. For this reason, regardless of the speed of the printing paper P, the edge of the printing paper P in the sub-scanning direction SS can be accurately detected. Therefore, it is possible to suppress the occurrence of ink mist and prevent the printed image from being stained. In addition, an optimum circuit constant capable of removing noise can be selected even under conditions where noise is likely to occur, such as a large format printer with a long FFC. Therefore, it is possible to prevent erroneous detection of the edge of the printing paper P due to noise.

  In the printing method according to the present embodiment, a relative speed setting step for setting the speed of the carriage 3, a plurality of speeds of the carriage 3, and the optical sensor 45 at each speed in the main scanning direction MS of the print paper P. A time constant calculating step of calculating an electrical time constant t based on the paper edge position of the printing paper P when the paper edge is detected. For this reason, by using the printing method, the electric time constant t is actually obtained by changing the speed of the carriage 3, and the electric edge constant is detected in the main scanning direction MS of the printing paper P during printing. The target time constant t can be used. Therefore, the end of the printing paper P in the main scanning direction MS can be detected more accurately during printing. Further, the electrical time constant t can be obtained by changing the speed of the printing paper P, and the electrical time constant t can be used to detect the paper edge of the printing paper P in the sub-scanning direction SS during printing. Therefore, the end of the printing paper P in the sub-scanning direction SS can be detected more accurately during printing.

  The preferred embodiments of the printing apparatus and the printing method according to the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit of the present invention. Is possible.

  In the above-described embodiment, the optical sensor 45 is a reflective photo interrupter. In addition, the optical sensor 45 may be a light emitting / receiving sensor in which the light emitting surface of the light emitting element and the light receiving surface of the light receiving element are arranged to face each other. The light receiving element 47 is a phototransistor, but the light receiving element 47 may be a photodiode. Furthermore, the configuration of the light emission intensity adjusting unit 50 is not limited to the above-described configuration. For example, a variable resistor may be used instead of the D / A converter 61. The transistor 60 may be an NPN transistor or a field effect transistor (FET). Further, the ink cartridge 21 may be fixed to the main body chassis 8 instead of the carriage 3. In this case, the ink cartridge fixed to the main body chassis 8 and the print head 2 mounted on the carriage 3 are connected by a flexible ink supply tube.

  The determination unit 73 is not necessarily provided. In that case, the printing apparatus does not perform the determination step (step S101, step S201, step S301, step S401). That is, the printing apparatus 1 calculates the paper edge position for any paper type without determining whether the paper edge position or the electrical time constant t needs to be calculated according to the type of the printing paper P. Alternatively, the electrical time constant t is calculated. Further, the edge position calculation unit 70 may calculate each position of only the paper edge of the printing paper P in the main scanning direction MS or only the paper edge of the printing paper P in the sub-scanning direction SS. Similarly, the time constant calculating unit 71 calculates the electrical time constant t in order to calculate the position of only the paper edge of the printing paper P in the main scanning direction MS or only the paper edge of the printing paper P in the sub-scanning direction SS. You may calculate. In addition, the determination unit 73 does not determine whether the paper type is likely to increase noise when calculating the time constant, but determines whether the paper type is likely to increase noise when calculating the paper edge position. You may do it.

  The time constant calculation unit 71 may calculate the electrical time constant t based on three or more different relative speeds. Further, in the main scanning direction MS, the relative speed between the optical sensor 45 and the printing paper P is the speed of the carriage 3, but the drive target is the carriage 3 if it is a member on which the optical sensor 45 is mounted. It is not limited. In addition to driving only the member on which the optical sensor 45 is mounted, only the printing paper P is driven, or both the member on which the optical sensor 45 is mounted and the printing paper P are driven. Anyway. Further, in the sub-scanning direction SS, the relative speed between the optical sensor 27 and the printing paper P is the speed of the printing paper P, but the drive target is only the member on which the optical sensor 27 is mounted, or the optical You may make it drive both the member carrying the type | formula sensor 27, and the printing paper P. FIG.

  The time constant calculating unit 71 or the time constant calculating step is not necessarily provided. In the assembly process of the printing apparatus 1, a specific electrical time constant t is stored in the storage unit 72, and the paper edge position is calculated using the specific electrical time constant t during printing. Also good. In addition to performing both the time constant calculation process and the paper edge position calculation process during the assembly process of the printing apparatus 1, the time constant calculation process is performed during the assembly process of the printing apparatus 1, and the paper edge position calculation process is performed in the printing apparatus 1. You may make it carry out at the time of use.

1 is a schematic configuration diagram of a printing apparatus according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of a portion related to paper feeding of the printing apparatus of FIG. 1. FIG. 3 is a schematic configuration diagram illustrating a detection mechanism of the carriage of FIG. 1 and the PF drive roller of FIG. 2. The front view which shows schematic structure of the optical sensor of FIG. The figure which shows schematic structure of the optical sensor and control part of FIG. The graph explaining the phenomenon recognized by the detection of the paper edge position of printing paper being shifted. The flowchart which shows the calculation process of the time constant of RC circuit shown in FIG. The flowchart which shows the calculation process of the time constant of RC circuit of the optical sensor of FIG. 6 is a flowchart showing a flow of processing for calculating a paper edge position in a main scanning direction. 6 is a flowchart showing a flow of processing for calculating a paper edge position in the sub-scanning direction. The figure which compared the printing area before and after correction | amendment of a paper edge position.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Printer, 2 Print head, 3 Carriage, 27 Optical sensor, 32 Optical sensor, 35 Optical sensor, 45 Optical sensor, 46 Light emitting element, 47 Light receiving element, 50 Light emission intensity adjustment part, 52 Internal power supply (power supply) , 60 transistors, 61 D / A converter, 62 RC circuit (noise removal means), 70 end position calculation section (end position calculation means), 71 time constant calculation section (time constant calculation means), 72 storage section (storage) Means), 73 discriminating section (discriminating means), 74 relative speed variable section (relative speed variable means), 75 printing paper information receiving section, P printing paper (printing object).

Claims (7)

A printing apparatus for printing on a print object,
An optical sensor for detecting the print object;
Noise removing means disposed on the output side of the optical sensor;
Based on the electrical time constant of the noise removing means, the relative speed between the optical sensor and the printing object when the optical sensor detects the edge of the printing object, and the edge position of the printing object. End position calculating means for calculating the original end position of the print object;
A printing apparatus comprising: A relative speed variable means for changing the relative speed;
When calculating the electrical time constant based on a plurality of the relative speeds and the end position of the print object when the end of the print object is detected by the optical sensor at each relative speed Constant calculation means;
The printing apparatus according to claim 1, further comprising:   Based on the type of the print object, the image forming apparatus further includes a determination unit that determines whether noise is likely to increase. When the determination unit determines that the noise is likely to increase, the end position calculation unit The printing apparatus according to claim 1, wherein an original end position of the print object is calculated.   Based on the type of the printing object, further includes a determination unit that determines whether noise is likely to increase, and when the determination unit determines that noise is likely to increase, the time constant calculation unit includes: The printing apparatus according to claim 1, wherein the electrical time constant is calculated.   The printing apparatus according to claim 1, wherein the optical sensor is mounted on a carriage that is scanned in a width direction of the print object. A printing method for printing on a print object,
An end detection step of detecting an end of the print object by an optical sensor;
Based on the electrical time constant of the noise removing means for removing noise from the output of the optical sensor, the relative speed between the optical sensor and the printing object in the detection of the edge, and the edge position of the printing object. An end position calculating step for calculating an original end position of the print object;
A printing method comprising: A relative speed setting step for setting the relative speed;
When calculating the electrical time constant based on a plurality of the relative speeds and the end position of the print object when the end of the print object is detected by the optical sensor at each relative speed A constant calculation step;
The printing method according to claim 6, further comprising:

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