JP4976117B2 - Printing device - Google Patents

Description

  The present invention relates to a printing apparatus, and more particularly, to an ink jet printing apparatus that performs color printing using a print head that forms dots of a plurality of colors.

  Conventionally, a print head that ejects ink on a carriage that reciprocates in a main scanning direction that is substantially perpendicular to the sheet feeding direction of a sheet-like print medium has a desired image / character on the print medium. An ink jet printing apparatus that records the above is used (see, for example, cited documents 1 to 3).

  In the ink jet printing apparatus, the position of the carriage is detected by reading a linear scale pattern having a plurality of patterns arranged at regular intervals along the sub-scanning direction. It is known to control ink ejection (see, for example, Patent Document 4). Furthermore, in order to form dots of a plurality of colors, a printing apparatus (inkjet printer) having a print head in which nozzle groups for ejecting each ink are arranged at a constant pitch along the sub-scanning direction that is the recording paper conveyance direction Is also known (see, for example, Patent Document 5).

  In the case of a general inkjet printer, the nozzle rows for each color of the print head are arranged along the main scanning direction substantially orthogonal to the transport direction of the printing medium (recording paper). In order to shorten the printing process time (improving the processing speed), the print head is reciprocated along the main scanning direction, and ink is ejected and printed during the forward movement and the backward movement.

  However, if the print head is reciprocated along the main scanning direction and ink is ejected and printed during the reciprocal movement, the overlapping order of the color inks is reversed between forward printing and reverse printing. There were problems such as color tone differences. For this reason, using a print head in which nozzle groups that discharge ink of each color are arranged at a constant pitch along the sub-scanning direction, which is the recording paper conveyance direction, in accordance with the reciprocation of the print head, By discharging ink during printing and when returning, problems due to color tone differences are eliminated.

Japanese Patent Publication No. 3-76226 JP 11-48503 A JP 2003-145877 A Japanese Patent Laid-Open No. 2004-90289 Japanese Patent No. 3740918 (FIG. 24)

  However, if printing is performed by ejecting ink at the time of forward and backward movement in accordance with the reciprocation of the print head as described above, each color ink is not affected by the color tone difference as described above. Is a so-called long head configuration in which the nozzle group that discharges the nozzle is arranged along the sub-scanning direction, which is the recording paper conveyance direction. There is a problem in that printing misalignment occurs due to misalignment of the ink ejection / landing position between the time and the backward movement, resulting in a decrease in printing accuracy.

  The present invention provides a printing apparatus that can perform high-precision and high-quality printing without causing printing misalignment between the printing process when the print head moves forward and the printing process when the print head moves backward. The task is to do.

In order to solve the above-described problems, the present invention provides a head that ejects ink onto a printing medium, and a carriage that includes the head and is movable in a main scanning direction that is substantially perpendicular to the conveyance direction of the printing medium. A linear scale extending along the main scanning direction and formed with a plurality of patterns, a sensor fixed to the carriage and reading the plurality of patterns formed on the linear scale, and read by the sensor Control means for controlling ejection of ink by the head based on the pattern, and the linear scale is disposed on the upstream side of the carriage in the transport direction of the print medium; and And a second linear scale disposed on the downstream side of the carriage in the transport direction of the print medium, and the sensor The a first sensor for reading a plurality of patterns formed on a first linear scale, Ri Do and a second sensor for reading a plurality of patterns formed on the second linear scale, said control means And a first counter and a second counter for counting patterns read by the first and second sensors when the head moves in the main scanning direction, respectively. obtains the position data of both ends of the head on the basis, it characterized that you prediction sets the ink ejection timing of the head on the basis of the deviation of the both end portions of the head according to this position data.

In the printing apparatus of the present invention, a head that ejects ink onto a printing medium, a carriage that has the head and is movable in a main scanning direction substantially orthogonal to the conveyance direction of the printing medium, and along the main scanning direction A linear scale that is extended to form a plurality of patterns, a sensor that reads the plurality of patterns that are fixed to the carriage and formed on the linear scale, and a controller that controls ejection of ink by the head based on the patterns read by the sensors The linear scale is disposed on the upstream side of the carriage in the conveyance direction of the printing medium, and the second linear scale is disposed on the downstream side of the carriage in the conveyance direction of the printing medium. A linear scale, and a sensor that reads a plurality of patterns formed on the first linear scale. If, Ri Do and a second sensor for reading a plurality of patterns formed on a second linear scale, the control means, the pattern being read by the first and second sensors during main scanning direction movement of the head, respectively It has first and second counters for counting, acquires position data at both ends of the head based on the counting results of the first and second counters, and shifts both ends of the head due to the position data. it predicted sets the ink ejection timing of the head based. According to the present invention, a pattern to be read by the first sensor, the both ends of the head is obtained based on the first and second counters counting result counting the pattern being read by the second sensor, respectively Based on the misalignment , the control means predicts and sets the ink ejection timing of the head and controls the ink ejection, so that the print misalignment or the like is performed by the print processing at the time of forward movement and the print processing at the time of backward movement in the main scanning direction of the head. High-precision and high-quality printing can be performed without causing it.

  In the present invention, it is preferable to further include a guide shaft that is arranged along the main scanning direction and guides the carriage, and this guide shaft is preferably arranged in the vicinity of the second linear scale in a substantially parallel shape. In addition, the head preferably includes a plurality of colors of ink that are provided along the conveyance direction of the printing medium and arranged in a predetermined order, and a plurality of nozzles that eject the inks of the plurality of colors. In such an aspect, the control means includes the first ink group ejected from the nozzle based on the pattern read by the first sensor and the second ink ejected from the nozzle based on the pattern read by the second sensor. A plurality of colors of ink constituting the ink group may be individually controlled for ejection.

Specifically, the control means includes first and second timer for measuring the period of the signal output from the first and second sensors by reading the pattern, respectively, said first and second timer The position data of both ends of the head are calculated based on the counting results of the first and second registers and the first and second counters that hold the cycle data measured by the above-described positions, and both ends of the head based on the position data are calculated. And a calculation unit that calculates the ink discharge timing of each color of the head based on the shift of the unit. At this time, when the deviation between both ends of the head based on the position data counted by the first and second counters is less than 2, the arithmetic unit precedes the first and second timers in the main scanning direction. Reads the linear scale pattern arranged on the other end side of the head moving with the output from the sensor reading the linear scale pattern arranged on the one end side of the moving head as a trigger. A sensor that reads the pattern on the other side by calculating the difference between the value of the previous cycle data of the register that holds the cycle data of the sensor and the value of the cycle data at that time of the sensor that reads the pattern on the other side Next, the cycle of the signal to be output next is obtained, the obtained cycle, the position information of the center position of each color of the head determined in advance, and the position information of both ends based on the position data. From the first and second timers, the ink ejection timing of each color of the head is calculated, and the deviation of both ends of the head based on the position data counted by the first and second counters is 2 or more. Arranged on the other end side of the head moving late with the input from the sensor reading the linear scale pattern arranged on the one end side of the head moving in the main scanning direction in advance as a trigger A sensor that reads the pattern on the other side from the value obtained by multiplying the value of the previous cycle data of the register that holds the cycle data of the sensor that reads the linear scale pattern by the difference between the counter values of the first and second counters By calculating the difference from the value of the period data at that point in time to obtain the period of the next signal output from the sensor reading the pattern on the other side. And the period was, the positional information of the center position of each color of heads predetermined from the position information of the both end portions by the position data, may be calculated ink ejection timing of each color of the head.

  In the present invention, it is preferable that the ink discharge timing of each color predicted and set by the control unit is set with reference to the center of the plurality of nozzles in each color, and the control unit performs ink reciprocation in the main scanning direction of the carriage. It is desirable to control the discharge so as to perform the discharge operation.

According to the present invention, a pattern to be read by the first sensor, the both ends of the head is obtained based on the first and second counters counting result counting the pattern being read by the second sensor, respectively Based on the misalignment , the control means predicts and sets the ink ejection timing of the head and controls the ink ejection, so that the print misalignment or the like is performed by the print processing at the time of forward movement and the print processing at the time of backward movement in the main scanning direction of the head. It is possible to obtain an effect that high-precision and high-quality printing can be performed without causing the occurrence.

  Hereinafter, an embodiment in which the present invention is applied to an ink jet printing apparatus will be described with reference to the drawings.

(Constitution)
As shown in FIG. 5, the printing apparatus 10 of the present embodiment is connected to the upper apparatus 1 (for example, a host computer such as a personal computer) via an interface (not shown), and is transferred from the upper apparatus 1 to the printing apparatus 10. It is possible to instruct a printing operation or the like by transmitting print data or the like. Note that the printing apparatus 10 includes an operation panel (operation panel) 50, and in addition to a printing operation instruction from the host apparatus 1, a printing operation instruction from the operation panel 50 is also possible.

  The host device 1 is generally generated by an image input device 2 such as a scanner for reading an image recorded on a document, an input device 3 such as a keyboard for inputting commands and data to the host device 1, and the host device 1. A monitor 4 such as a liquid crystal display for displaying data or the like is connected.

  As shown in FIG. 1, the printing apparatus 10 is provided on one side (the right side in FIG. 1), and is inclined so that a plurality of sheets (not shown) as printing media before printing can be stacked and held. A paper feed tray 11 provided, a conveyance belt 12 that intermittently conveys a sheet to be printed in one direction, and a conveyance direction of the sheet conveyed by the conveyance belt 12 (the direction of arrow A shown in FIG. A printing unit 20 having a print head 21 that prints a sheet while reciprocating in a direction (arrow B direction shown in FIG. 1) substantially orthogonal to the conveyance direction A, and the other side (see FIG. 1 is provided obliquely on the left side of 1 and includes a paper discharge tray 14 for storing printed sheets.

  The conveyor belt 12 is composed of a plurality (two) of endless belts, and each belt has a plurality of suction holes 13 formed on the surface thereof so that the sheet can be sucked by a vacuum mechanism (not shown). Yes. The conveyance belt 12 is rotatably attached so as to convey the sheet along the sheet conveyance direction A while sucking the sheet through the plurality of suction holes 13 (see also FIG. 2).

  As shown in FIGS. 1 to 3, the printing unit 20 can reciprocate in the main scanning direction (the direction of arrow B in FIG. 1, hereinafter referred to as the main scanning direction B) that is substantially perpendicular to the sheet conveying direction A. A plurality of color ink cartridges 23a, 23b, 23c, and 23d are arranged on the carriage 22 in a predetermined order along the sub-scanning direction that is the same as the sheet conveying direction A. Are integrally provided.

  In this embodiment, from the upstream side to the downstream side in the sheet conveying direction A, the cartridge 23a that holds black (K) ink therein, the cartridge 23b that holds cyan (C) ink inside, and magenta (M) The cartridge 23c that holds the ink in the inside and the cartridge 23d that holds the yellow (Y) ink in the inside are arranged in series (in a straight line) so that printing (ink ejection) can be performed in order of darkness on the sheet. ing. Note that the printing unit 20 having the print head 21 employs a conventionally known ink jet method, and the ink ejection configuration thereof is that of the known technology described in the background art section (see, for example, Patent Documents 1 and 2). ), And a detailed description thereof is omitted here.

  A part of the carriage 22 is fixed to a toothed drive belt 25 that receives a driving force transmitted from a DC motor 24 (see FIG. 2) that can be rotated in the forward and reverse directions, so that the drive belt 25 rotates in the forward and reverse directions. In addition, the print head 21 (multiple color ink cartridges 23a, 23b, 23c, 23d) can be reciprocated in the main scanning direction B.

  A guide shaft 26 that guides the carriage 22 is juxtaposed in parallel with the drive belt 25 so that the carriage 22 can stably reciprocate. A bearing 27 (see FIG. 3) through which the guide shaft 26 is inserted is provided on one end side of the carriage 22 (on the downstream side of the print head 21 with respect to the sheet conveyance direction A). The carriage 22 supports the print head 21 by cantilever support.

  As described above, the print head 21 uses the ink cartridges 23a (black: K), 23b (cyan: C), 23c (magenta: M), and 23d (yellow: Y) provided on the carriage 22. As shown in FIG. 4, it is integrally provided so as to be arranged in a predetermined order along the sub-scanning direction that is the same as the sheet conveying direction A, but the surface side facing the sheet Corresponding to the ink car cartridges of each color (23a (black: K), 23b (cyan: C), 23c (magenta: M), 23d (yellow: Y)) A plurality are provided for each. In this embodiment, the ink in the blank (K) ink cartridge 23a and the ink in the cyan (C) ink cartridge 23b constitute the first ink group, and the ink in the magenta (M) ink cartridge 23c and The ink of the yellow (Y) ink cartridge 23d constitutes the second ink group.

  In this embodiment, the black (K) ink ejecting nozzle 28a of the ink car cartridge 23a, the cyan (C) ink ejecting nozzle 28b of the ink cartridge 23b, and the magenta (M) ink ejecting of the ink cartridge 23c are ejected. 600 nozzles 28d for ejecting yellow (Y) ink of the ink cartridge 23d and the ink cartridge 23d are arranged in a straight line for each color (in FIG. 4, seven nozzles 28a to 28d for each color are arranged in each of seven. This is schematically shown by the nozzle.) In this embodiment, each color has a head length of 1 inch (4 inches for 4 colors) and dots are formed for each nozzle, so the print head 21 has a resolution of 600 DPI (Dot Per Inch). is doing. As will be described later, the ink ejection timing of each color predicted and set in the present invention is set with reference to the central nozzles 28ac, 28bc, 28cc, and 28dc of the plurality of nozzles 28a, 28b, 28c, and 28d in each color. Is done.

  As shown in FIGS. 1 to 3, the printing apparatus 10 has a linear scale 31 (31 a, 31 b) that has a plurality of patterns 32 formed on its surface and extends along a main scanning direction that is a moving direction of the print head 21. ) And sensors 33 (33a, 33b) that optically read a plurality of patterns 32 are arranged in pairs in the same position on the upstream side of the print head 21 with respect to the sheet conveying direction A as well as on the downstream side. Has been.

  The plurality of patterns 32 formed on the surface of the linear scale 31 (31a, 31b) and read by the optical sensor 33 (33a, 33b) have strip-shaped scales formed in the vertical direction at intervals of 150 LPI (Line Per Inch). Is arranged (see FIG. 6). The linear scale 31 (31a, 31b) is composed of a PET film. In this embodiment, the optical sensor 33 (33a, 33b) that reads the pattern 32 is a transmission sensor including a light emitting element and a light receiving element, and is fixed to both ends of the carriage 22.

  Further, as shown in FIG. 5, the printing apparatus 10 includes a control unit 40 as a control unit. The control unit 40 includes a buffer memory 35 that receives a signal supplied from the host apparatus 1 and stores print data, and a system controller 41 that controls the operation of the entire printing apparatus 10.

  The system controller 41 includes a trigger generation unit 49 that generates an ink discharge trigger of 600 DPI from output signals from the first sensor 33a and the second sensor 33b, and a first optical that reads the pattern 32 from the first linear scale 31a. The first timer 42a that measures the cycle of the input signal (ON / OFF or High / Low) from the sensor 33a, and the input signal from the second optical sensor 33b that similarly reads the pattern 32 from the second linear scale 31b. A timer 42 having a second timer 42b for measuring a cycle (ON / OFF or High / Low) and a first signal for counting an input signal (ON / OFF or High / Low) from the first optical sensor 33a. The input signal (O from the counter 43a and the second optical sensor 33b similarly. / OFF or High / Low), a counter 43 having a second counter 43b, a first register 44a holding a timer value for each period measured by the first timer 42a, and a second register A register 44 having a second register 44b for holding a timer value for each period measured by the timer 42b, a timer 42, a counter 43, and an arithmetic unit 45 for calculating based on data values from the register 44; It consists of

  Here, the trigger generation unit 49 will be described in detail. As shown in FIG. 6, the first and second sensors 33a and 33b for reading a pattern formed on the linear scale 31 (31a and 31b) at an interval of 150 LPI are as follows. A 90-degree A-phase and B-phase signal output is possible (known technology, for example, see Patent Document 3), and the trigger generation unit 49 is configured to output signals from the first and second sensors 33a and 33b. A trigger at the time of printing (ink ejection) is generated based on four timings at the time of rising and falling of each signal, and is output to the calculation unit 45. This trigger is 150 × 4 = 600 (DPI). The first and second timers 42 (42 a and 42 b) and the first and second counters 43 (43 a and 43 b) are connected to the first and second sensors 33 ( 33a and 33b) (in FIG. 5, the inside of the trigger generation unit 49 is indicated by a broken line).

  The control unit 40 mounts the print head 21 under the control of the ink discharge control unit 46 and the system controller 41 that control the discharge of each color ink of the print head 21 in accordance with the ink discharge timing calculated by the calculation unit 45. A sheet drive drive for conveying a sheet under the control of a carriage drive control unit 47 for controlling a drive motor 24 (DC motor) for driving a carriage drive mechanism for reciprocating the carriage 22 to be placed, and the system controller 41. The sheet conveyance control unit 48 is configured to control a drive motor (stepping motor) 29 for driving the mechanism (including the conveyance belt 12 and the like).

(Operation)
Next, the operation of the printing apparatus 10 of the present embodiment will be described focusing on the operation of the system controller 41.

  The printer driver installed in the host apparatus 1 determines various parameter values for controlling the printing operation of the printing apparatus 10 based on the printing method designated by the user, and print data for performing printing in the printing method. Is transmitted to the printing apparatus 10. The buffer memory 35 of the control unit 40 stores image data of a plurality of color components obtained by separating the print data for each color component.

  The sheet conveyance control unit 48 operates the vacuum mechanism in accordance with a control signal from the system controller 41 and drives the drive motor 29 constituting the sheet conveyance drive mechanism to convey the sheet in the sheet conveyance direction A. When a sheet is conveyed in a predetermined amount (corresponding to the width of the ink cartridge for each color) in the sheet conveyance direction A, the carriage drive control unit 47 is driven by a drive motor 24 that constitutes a carriage drive mechanism in accordance with a control signal from the system controller 41. Is driven (forward rotation). The ink ejection control unit 46 reads out image data of each color component from the buffer memory 35 in accordance with a control signal from the system controller 41, and configures the print head 21 according to the ink ejection timing for each color instructed from the arithmetic unit 45 ( 28a, 28b, 28c, and 28d), ink for each color is ejected toward the sheet. This operation is the same as the printing operation of the conventional ink jet printing apparatus.

  In the printing apparatus 10 according to the present embodiment, since the print head 21 is long, when the carriage 22 is reciprocated in the main scanning direction B, the print head 21 is accompanied by mechanical backlash and bending. This prevents the printing accuracy (quality) from deteriorating due to a deviation in the ink protruding position and the landing position of the ink discharged from the nozzle 28 on the sheet at each time.

  For this reason, the characteristics of the system controller 41 of the present embodiment can be summarized as follows. The patterns of the first and second linear scales 31 (31a, 31b) arranged on both sides of the carriage 22 (print head 21) are the first and second patterns. By reading with the second sensor 33 (33a, 33b), the calculation unit 45 of the system controller 41 acquires the position data of both ends of the carriage 22 (print head 21) in the main scanning direction B, and based on this position data. Based on the misalignment between both ends of the carriage 22 (print head 21), the ink discharge timing of each color discharged from the print head 21 (nozzle 28) is predicted and set, and the ink discharge control unit 46 is instructed about the ink discharge timing However, the details are as follows.

  First, in a state where the print head 21 is completely stopped, the first and second counters 43 (43a, 43b) are initialized (for example, both counter values are set to 0), and the print head 21 is straightened. The position data of both ends that can be printed on is acquired. This position data is used to manage the start / end positions of printing when the print head 21 is moved in the main scanning direction B, and as described later, the calculation unit 45 stores the first and second counters 43. By comparing the counter values, it is used as an initial counter value for managing a case where one of both ends is delayed (deviation occurs) when the print head 21 moves in the main scanning direction B.

  The first and second counters 43 (43a, 43b) increment or decrement the counter value according to signals (see also FIG. 6) output from the first and second sensors 33 (33a, 33b).

  The signals from the first and second sensors 33 (33a, 33b) are input to the first and second timers 42 (42a, 42b), respectively, and the first and second timers 42 are And the period of the input signal from the 2nd sensor 33 is measured, respectively, and a measurement result is output to the calculating part 45 and the 1st and 2nd register | resistor 44 (44a, 44b). Each time the timer value (Timer0a) is input from the first timer 42a, the first register 44a holds or backs up the timer value as Timer1a and clears the timer value (Timer0a) of the first timer 42a. The held timer value (Timer1a) is output to the calculation unit 45. Similarly, each time a timer value (Timer0b) is input from the second timer 42b, the first register 44b holds or backs up the timer value as Timer1b and stores the timer value (Timer0b) of the second timer 42b. Clear and output the held timer value (Timer1b) to the arithmetic unit 45.

  Therefore, at a specific time, the arithmetic unit 45 has the timer value (Timer0a) from the first timer 42a and the timer value (Timer1a) immediately before the first timer 42a held in the first register 44a. The timer value (Timer0b) from the second timer 42b and the timer value (Timer1b) immediately before the second timer 42b held by the second register 44b are output.

  FIG. 7 shows the first and second cases where the end of the print head 21 on the first sensor 33a side moves in the main scanning direction B later than the end of the print head 21 on the second sensor 33b side. The output from the sensor 33 and the counter values of the first and second counters 43 are schematically shown. In the drawing, Timer1a represents the previous timer value held by the first register 44a, as described above, and Timer0a represents the current value output from the first timer 42a ( It represents the timer value (when the signal is output from the second sensor 33b).

  When the end portion of the print head 21 on the first sensor 33a side moves in the main scanning direction B later than the end portion of the print head 21 on the second sensor 33b side, the calculation unit 45 uses the second sensor When the signal from 33b is output (when the timer value is output from the second timer 42b), that is, as indicated by a broken line in FIG. 7 using the signal output from the second sensor 33b as a trigger. Then, the time T until the next signal output from the first sensor 33a (the time until the timer value is output from the first timer 42a) T is calculated as (Timer1a-Timer0a). That is, since the timer value (Timer1b) held by the first register 44a is the actual value (backup) of the signal output from the first sensor 33a, the arithmetic unit 45 outputs a signal with a substantially similar cycle. The period of the next signal output is predicted by subtracting the current (intermediate) timer value (Timer0a) from the actual value.

  In FIG. 7, prediction is made when the end of the print head 21 on the first sensor 33 a side moves in the main scanning direction B later than the end of the print head 21 on the second sensor 33 b side. On the other hand, when the end of the print head 21 on the second sensor 33b side is moved in the main scanning direction B with a delay, the signal from the second sensor 33b is output until the next time. The time T (the time until the timer value is output from the second timer 42b) T is calculated as (Timer1b-Timer0b). The computing unit 45 determines which is delayed by comparing the counter values of the first and second counters 43 (43a, 43b) (see FIG. 7). That is, the deviation between both ends of the print head 21 is detected by calculating the difference between the counter values of the first and second counters 43.

  Next, the computing unit 45 determines whether or not the difference between the counter values of the first and second counters 43 is less than 2.

  When an affirmative determination is made (when the difference between the counter values of the first and second counters 43 is less than 2), the above-described time T (cycle) and the centers 28ac of the nozzles 28a, 28b, 29c, and 28d of the respective colors, From the position information (predetermined value) of 28bc, 28cc, and 28dc and the counter values of the first and second counters 43 (position information of both ends of the print head 21), the nozzles 28a, 28b, 29c, and 28d of the respective colors are detected. Ink discharge timing is calculated.

  On the other hand, when the determination is negative (when the difference between the counter values of the first and second counters 43 is 2 or more), the end of the print head 21 on the first sensor 33a side is replaced with the time T described above. When moving in the main scanning direction B with a delay, T = Timer1a × (counter value of the second counter 43b−counter value of the first counter 43a) −Timer0a is calculated, and the second sensor 33b side When the end of the print head 21 is moved in the main scanning direction B with a delay, T = Timer1b × (counter value of the first counter 43a−counter value of the second counter 43b) −Timer0b is calculated. The calculated time T, the positional information of the centers 28ac, 28bc, 28cc, 28dc of the nozzles 28a, 28b, 29c, 28d of the respective colors, and the first and second counters 43 From the counter value (position information of both ends of the print head 21), the ink ejection timing of each color nozzle 28a, 28b, 29c, 28d is calculated.

  When the deflection amount of the print head 21 (the difference between the counter values of the first and second counters 43) is small, the calculation unit 45 sets the blank (K) ink cartridge 23a constituting the first ink group described above. The ink discharge timing of the nozzles 28a and 28b for discharging the ink and the ink of the cyan (C) ink cartridge 23b is synchronized with the output signal of the first sensor 33a, and magenta (M) constituting the second ink group Even if the ink ejection timings of the nozzles 28c and 28d that eject the ink of the ink cartridge 23c and the ink of the yellow (Y) ink cartridge 23d are synchronized with the output signal of the second sensor 33a, high printing accuracy (quality ) Can be ensured, but as the amount of deflection of the print head 21 increases, the printing accuracy increases. Inferiority occurs. As will be described below, the calculation unit 45 of this embodiment ensures high printing accuracy even when the amount of deflection of the print head 21 is large.

  FIG. 8 shows the time T and the centers 28ac of the nozzles 28a, 28b, 29c, 28d of the respective colors when the end of the print head 21 on the first sensor 33a side is moved in the main scanning direction B with a delay. It is a timing chart which shows the relationship with the ink discharge timing from 28bc, 28cc, and 28dc. Specifically, T = T1 + T0 + T0 + T0 + T1, and the time T represents the relationship between the ejection timings T0 and T1 from the nozzles 28a, 28b, 29c, and 28d of the respective colors. T1 depends on the distance between the first and second sensors 33 and the positions of the K and Y color nozzle centers 28ac and 28dc, and T1 is at the positions of the KCMY color nozzle centers 28ac, 28bc, 28cc and 28dc. Dependent. Therefore, the calculation unit 45 predicts when the signal output from the first sensor 33a is performed at the time when the signal output from the second sensor 33b is received (time T), and the physical output of the nozzle is determined accordingly. An ink ejection timing for each color is calculated (predicted setting) by adding a position (distance) element.

  The calculation unit 45 outputs a signal to the ink discharge control unit 46 in accordance with the calculated ink discharge timing for each color. Accordingly, the ink ejection control unit 46 ejects ink for each color from the nozzles 28a, 28b, 28c, and 28d of the print head 21, and sequentially forms an image on the sheet (printing processing is executed).

  The arithmetic unit 45 monitors the counter values of the first and second counters 43, and when the counter value reaches a predetermined value, outputs a signal to the carriage drive control unit 47 to configure the carriage drive mechanism. The drive motor 24 is rotated in the reverse direction, and printing (printing process) is performed by reciprocating the sheet in the main scanning direction B. The first and second counters 43 increment the counter value when the carriage 22 moves forward, and decrement the counter value when the carriage 22 moves backward.

  During this time, the sheet conveyance control unit 48 operates the vacuum mechanism and drives the drive motor 29 to convey the sheet in the sheet conveyance direction A as described above. When a sensor (not shown) for detecting the trailing edge of the sheet detects the trailing edge of the sheet, the sheet conveyance control unit 48 terminates the operation of the vacuum mechanism, but the printed sheet is placed on the discharge tray 14. The driving motor 29 continues to be driven for a predetermined time until the printed sheet is placed on the discharge tray 14 until the driving motor 29 is driven. Thus, when printing on the first sheet is completed and there is a print job for the second sheet, the above operation is repeated.

(Effects etc.)
Next, effects and the like of the printing apparatus 10 according to the present embodiment will be described.

  The printing apparatus 10 according to this embodiment includes a 4-inch print head 21. When such a long head is used for reciprocal printing with cantilever support, printing misalignment may occur between the forward path and the backward path due to mechanical backlash or deflection, which may reduce printing accuracy and print quality. There is. In order to prevent this, the printing apparatus 10 is formed on the linear scale 31 by arranging the linear scales 31 along the main scanning direction B on both the upstream side and the downstream side in the sheet conveying direction of the print head 21. A configuration was adopted in which the patterns were read by the first and second sensors 33 and the ink discharge timings of the respective colors from the nozzles were predicted and set based on the misalignment between both ends of the print head 21. For this reason, according to the printing apparatus 10 of the present embodiment, high-precision and high-quality printing is performed without causing printing misalignment between the print processing when the print head 21 moves forward and the print processing when the print head 21 moves backward. be able to. Further, by using the print head 21 as a cantilever support, the size of the entire printing apparatus 10 can be suppressed, and factors that simplify the mechanism and increase the cost can be suppressed.

  In the present embodiment, the conveyance belt 12 for conveying the sheet to be printed sucks the sheet by the vacuum mechanism. However, the present invention is not limited to this configuration. You may make it employ | adopt the sheet | seat conveyance mechanism by a suction system. In this case, in order to improve the quality, it is preferable that the print area portion of the sheet corresponding to the entire print head 21 is positioned so as to be as flat as possible without being uneven.

  In the present embodiment, the so-called cantilever support configuration of the so-called print head 21 is exemplified. However, this cantilever support configuration is configured such that the guide shaft 26 and the bearing 27 are connected to the other end side of the carriage 22 (in the sheet conveyance direction). In contrast, the guide shaft 26 and the bearing 27 may be provided on both ends of the carriage 22 (upstream and downstream of the print head 21 with respect to the sheet conveying direction). It is good also as what is called a both-end support structure provided in (4).

  Furthermore, in the present embodiment, the first and second sensors 33a and 33b are exemplified by transmission sensors including light emitting elements and light receiving elements. However, the present invention is not limited to this, and the linear sensors 31a and 31b are formed. It is only necessary to be able to detect the presence or absence (ON / OFF) of a scale as a patterned pattern.

  In the present embodiment, the logic circuit is exemplified in the system controller 41 that constitutes the control unit 40. However, the logic circuit may be constituted by a CPU (Central Processing Unit) or the like.

  The present invention provides a printing apparatus capable of performing high-accuracy and high-quality printing without causing printing misalignment between the printing process when the print head moves forward and the printing process when the print head moves backward. Since it contributes to the manufacture and sale of printing devices, it has industrial applicability.

1 is an external perspective view of a printing apparatus according to an embodiment to which the present invention is applicable, with an upper cover omitted. 1 is a perspective view of a printing apparatus according to an embodiment in which a casing, a paper feed tray, and a paper discharge tray are omitted. FIG. 3 is a perspective view of the printing apparatus according to the embodiment in which a casing, a paper feed tray, and a paper discharge tray are omitted, and is a perspective view when viewed from an angle different from FIG. 2. It is a perspective view when the printing head used for the printing apparatus of an embodiment is shown typically and it sees from the lower part. FIG. 2 is a block diagram illustrating a schematic configuration of a control unit of the printing apparatus according to the embodiment. It is explanatory drawing which shows the relationship between the pattern formed in the linear scale, the 1st and 2nd sensor, and a trigger production | generation part. It is a timing chart which shows the relationship between the signal output of the 1st and 2nd sensor, and a timer, a register, and a counter. It is a timing chart which shows the signal output of the 1st and 2nd sensor, and the ink discharge timing of the nozzle of each color of KCMY.

Explanation of symbols

21 Print head
22 Carriage 23a, 23b, 23c, 23d Ink cartridge 26 Guide shaft 28a, 28b, 28c, 28d Nozzle 31a First linear scale 31b Second linear scale 33a First sensor 33b Second sensor 40 Control section (control means) )
42a first timer 42b second timer 43a first counter 43b second counter 44a first register 44b second register 45 arithmetic unit

Claims (8)

A head that ejects ink onto a printing medium; a carriage that includes the head and is movable in a main scanning direction substantially perpendicular to a conveyance direction of the printing medium; and extends along the main scanning direction. A linear scale on which a plurality of patterns are formed; a sensor that is fixed to the carriage and that reads the plurality of patterns that are formed on the linear scale; and that the ink is ejected by the head based on the patterns that are read by the sensor. Control means for controlling, wherein the linear scale is disposed on the upstream side of the carriage in the transport direction of the print medium, and downstream of the carriage in the transport direction of the print medium. And a second linear scale disposed on the side, wherein the sensor is shaped into the first linear scale. A first sensor for reading a plurality of patterns, wherein Ri Do and a second second sensor for reading a plurality of patterns formed on the linear scale, said control means, the main scanning direction movement of the head The first and second counters for counting the patterns read by the first and second sensors at the time, respectively, and the positions of both ends of the head based on the counting results of the first and second counters. obtains the data, the printing apparatus characterized that you prediction sets the ink ejection timing of the head on the basis of the deviation of the both end portions of the head according to this position data. 2. The guide shaft according to claim 1, further comprising a guide shaft that is disposed along the main scanning direction and guides the carriage, and the guide shaft is disposed substantially parallel to the vicinity of the second linear scale. Printing device. The head includes a plurality of colors of ink that are provided along a transport direction of the print medium and arranged in a predetermined order, and a plurality of nozzles that eject the inks of the colors. Item 4. The printing apparatus according to Item 1. The control means includes a first ink group ejected from the nozzle based on a pattern read by the first sensor, and a second ink ejected from the nozzle based on a pattern read by the second sensor. The printing apparatus according to claim 3, wherein the plurality of colors of ink constituting the group are individually controlled to be ejected. The control means measures the first and second timers that measure the periods of signals output from the first and second sensors by reading the pattern, and the first and second timers, respectively. The position data of the both ends of the head is calculated based on the count results of the first and second registers holding the cycle data and the first and second counters, and both ends of the head based on the position data are calculated. The printing apparatus according to claim 3 , further comprising: a calculation unit that calculates an ink discharge timing of each color of the head based on a shift of the unit. When the deviation between both ends of the head based on the position data counted by the first and second counters is less than 2, the arithmetic unit precedes the main timer among the first and second timers. The output from the sensor that reads the pattern of the linear scale arranged on one end of the head moving in the scanning direction is used as a trigger, and the linear scale arranged on the other end of the head moving late By calculating the difference between the value of the previous cycle data of the register that holds the cycle data of the sensor that reads the pattern and the value of the cycle data at that time of the sensor that reads the pattern on the other side, A period of a signal to be output next from the sensor that reads the pattern on the side, the obtained period, and position information of a predetermined center position of each color of the head; The ink discharge timing of each color of the head is calculated from the position information of the both ends by the position data, and the deviation of the both ends of the head by the position data counted by the first and second counters is 2. In the above case, the input from the sensor that reads the linear scale pattern arranged on the one end side of the head that has moved in the main scanning direction in advance among the first and second timers as a trigger. The first and second counters are set to the value of the previous cycle data of the register that holds the cycle data of the sensor that reads the pattern of the linear scale arranged on the other end side of the head moving late. By calculating the difference from the value of the period data of the sensor that reads the pattern on the other side from the value obtained by multiplying the difference between the counter values of A period of a signal output next from a sensor that reads the pattern on the other side, the determined period, position information of a center position of each color of the predetermined head, and the both end portions based on the position data The printing apparatus according to claim 5 , wherein the ink discharge timing of each color of the head is calculated from the position information of the head. The printing apparatus according to claim 5 or 6 , wherein the ink ejection timing of each color predicted and set by the control unit is set based on a center of a plurality of nozzles in each color. Wherein, the printing apparatus according to any one of claims 1 to 7, characterized in that the ejection control so as to perform the ejection operation of the ink at the time of reciprocating in the main scanning direction of the carriage.

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