JP2017087545A - Image formation device, program and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control discharging of ink within a dischargeable range with more sureness.SOLUTION: An image formation device which forms an image on a print medium includes a nozzle for discharging an image formation substance, a position information acquiring means for acquiring position information of the nozzle on a surface of the print medium, and a position predicting means for deciding a predicted position information representing a next discharge position of the nozzle based on a past position information of the nozzle and a current position information of the nozzle. The position prediction means decides a predicted position information of the nozzle at a cycle shorter than the cycle for acquiring a position information of the nozzle.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus, a program, and a method.

  A hand-held printer (hereinafter referred to as HHP (Hand Held Printer)) that forms an image by scanning the apparatus with a user's hand on paper and ejecting ink from the apparatus when it reaches the image forming position is being put into practical use. is there. Since the HHP does not have a paper transport unit, it is a size that can be carried by the user.

  FIG. 1 is an example of a diagram schematically illustrating image formation by the HHP 1. The HHP 1 receives image data from an image data output device 9 such as a smartphone or a PC (Personal Computer). The user holds the HHP 1 and causes the HHP 1 to scan on the paper freehand. The HHP 1 includes a position detection sensor and an IJ recording head on the bottom surface in contact with the paper surface. The HHP 1 detects the position on the paper by a position detection sensor, and ejects ink from the IJ (Ink Jet) recording head when the IJ recording head reaches the ejection position. Since the portion where ink has already been ejected is masked, the HHP 1 does not eject ink even if it reaches the once ejected portion again.

  The HHP 1 predicts the position of its own device ahead of a predetermined time on the basis of the current position and the moving speed of its own device, etc., assuming that it moves from the current position at a constant speed. The HHP 1 determines whether or not the predicted position ahead for a predetermined time is an ejectable region. When the predicted position is included in the ejectable area, the HHP 1 ejects ink when the predicted position is reached, and when the predicted position is not included in the ejectable area, the HHP 1 does not eject ink when the predicted position is reached.

  For example, when the encoder cycle of the printer apparatus is one interval, a method for predicting the next encoder cycle based on the previous interval and the previous interval and determining the next ejection timing according to the predicted next encoder cycle Is known (see, for example, Patent Document 1).

  However, in the related art, when there is a sudden change in the moving speed of the HHP, there is a case where ink is not ejected to the ejectable region.

  For example, when the HHP scanning speed suddenly increases, the predicted position of the apparatus may go beyond the nearby dischargeable area to the discharge impossible area, and as a result, ink may not be discharged to the dischargeable area. .

  On the other hand, the phenomenon that ink is not ejected to the ejectable region can be reduced by shortening the period for acquiring the sensor value from the position detection sensor. However, due to the structure of the sensor, there is a limit to shortening the period for acquiring the sensor value.

  In view of the above problems, an object of the present embodiment is to perform control so as to discharge ink more reliably in a dischargeable range.

  In the disclosed technology, an image forming apparatus that forms an image on a print medium, the nozzle that discharges an image forming material, the position information acquisition unit that acquires the position information of the nozzle on the surface of the print medium, and the nozzle Position prediction means for determining predicted position information indicating the next discharge position of the nozzle from the previous position information of the nozzle and the current position information of the nozzle, and the position prediction means includes the position information of the nozzle There is provided an image forming apparatus characterized in that the predicted position information of the nozzle is determined in a cycle shorter than a cycle of acquiring the nozzle.

  Control can be performed so that ink is ejected to the ejectable range more reliably.

It is an example of the figure which shows the image formation by HHP typically. It is a figure which shows the hardware constitutions of HHP. It is an example of the figure explaining the structure of a control part. It is a figure which shows the timing chart of the process performed in a control part. It is a figure which shows the timing chart of the image processing of a reference example. It is a figure which shows the positional relationship of a sensor and a nozzle. It is a figure for demonstrating the position calculation method of a sensor. It is a figure for demonstrating calculation of the head nozzle position. It is a figure for demonstrating calculation of the position of the nozzle in the middle of a head and a tail nozzle. It is a figure explaining the pixel conversion of the unit of the position coordinate of each nozzle. It is a figure for demonstrating the determination of discharge. It is a figure which shows the flow of an image formation process. It is a figure for demonstrating calculation of the predicted position of a nozzle in case HHP scans at equal speed. It is a figure which shows the example of the PID parameter value set for every speed. It is a figure for demonstrating calculation of the predicted position of a nozzle when the scanning speed of HHP20 changes.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has substantially the same function structure, the duplicate description is abbreviate | omitted by attaching | subjecting the same code | symbol.

[Embodiment 1]
<Hardware configuration>
FIG. 2 is a diagram illustrating a hardware configuration of the HHP 20. The HHP 20 is an example of an image forming apparatus that forms an image on a print medium. The overall operation of the HHP 20 is controlled by a control circuit 25. The control circuit 25 includes a communication I / F (Interface) 27, an IJ recording head drive circuit 23, an OPU (Operation Unit) 26, a ROM (Read Only Memory) 28, A DRAM (Dynamic Random Memory) 29 and a sensor 30 are electrically connected. Further, since the HHP 20 is driven by electric power, it has a power source 22 and a power source circuit 21. The electric power generated by the power supply circuit 21 is supplied to the communication I / F 27, the IJ recording head driving circuit 23, the OPU 26, the ROM 28, the DRAM 29, the IJ recording head 24, the control circuit 25, and the sensor 30 by wiring shown by dotted lines. Yes.

  The power source 22 is mainly a battery. A solar cell, a commercial power source (AC power source), a fuel cell, or the like may be used. The power supply circuit 21 distributes the power supplied from the power supply 22 to each part of the HHP 20. Further, the voltage of the power supply 22 is stepped down or boosted to a voltage suitable for each part. In addition, when the power source 22 can be charged by a battery, the power source circuit 21 detects the connection of the AC power source and connects it to the battery charging circuit so that the power source 22 can be charged.

  The communication I / F 27 receives image data from the image data output device 9 such as a smartphone or a PC. The communication I / F 27 is a communication device corresponding to a communication standard such as a wireless LAN, Bluetooth (registered trademark), NFC (Near Field Communication), infrared, 3G (mobile phone), or LTE (Long Term Evolution). In addition to such wireless communication, a communication device that supports wired communication using a wired LAN, a USB cable, or the like may be used.

  The ROM 28 stores firmware that performs hardware control of the HHP 20, drive waveform data of the IJ recording head 24 (data that defines voltage changes for ejecting droplets), initial setting data of the HHP 20, and the like.

  The DRAM 29 is used for storing image data received by the communication I / F 27 and storing firmware developed from the ROM 28. Therefore, it is used as a work memory when the CPU 31 executes the firmware.

  The sensor 30 is a sensor that detects the position of the HHP 20. The sensor 30 includes, for example, a light source such as a light emitting diode (LED) or a laser and an image sensor that images the print medium 2 or a sensor that images interference fringes of incident / reflected light. When the HHP 20 is scanned over the print medium 2, minute edges of the print medium 2 are detected one after another (imaged), and the amount of movement is obtained by analyzing the distance between the edges. The sensors 30 are mounted on at least two places of the HHP 20. When distinguishing both, it is called sensors 30a and 30b. In addition, as the sensor 30, a multi-axis acceleration sensor, a gyro sensor, or the like may be used, or the position of the HHP 20 may be detected only by the acceleration sensor or the gyro sensor.

  The OPU 26 includes an LED 6 that displays the state of the HHP 20, a switch (for example, a calibration button 5) for the user to instruct the HHP 20 to form an image, and the like. However, the present invention is not limited to this, and may have a liquid crystal display and may further have a touch panel. Further, it may have a voice input function.

  The IJ recording head driving circuit 23 generates a driving waveform (voltage) for driving the IJ recording head 24 using the above driving waveform data. A drive waveform corresponding to the ink droplet size can be generated.

  The IJ recording head 24 is a head for ejecting ink. In the figure, four colors of CMYK ink can be ejected, but it may be a single color or ejecting five or more colors. A plurality of nozzles for ink ejection (described later) arranged in one row (may be two or more rows) for each color are arranged. Further, the ink ejection method may be a piezo method or a thermal method, or any other method.

  The control circuit 25 determines the position of each nozzle of the IJ recording head 24, the image to be formed according to the position, the determination of whether or not the ejection nozzle is available, based on the movement amount detected by the sensor 30. In the ejection nozzle availability determination, it is determined whether or not to eject ink depending on whether or not a position where the nozzle is expected to be ejected (hereinafter, target ejection position) is included in the allowable error range from the nozzle position. Details of the control circuit 25 will be described below.

  FIG. 3 is an example of a diagram illustrating the configuration of the control circuit 25. The control circuit 25 includes a SoC (System On a Chip) 50 and an ASIC (Application Specific Integrated Circuit) / FPGA (Field Programmable Gate Array) 40. The SoC 50 and the ASIC / FPGA 40 communicate via a bus 45 and a bus 46. It means that the ASIC / FPGA 40 may be designed by any mounting technology, and may be configured by other mounting technology other than the ASIC / FPGA 40. Further, the SoC 50 and the ASIC / FPGA 40 may be configured as a single chip or substrate without using separate chips. Alternatively, it may be implemented with three or more chips or substrates.

  The SoC 50 has functions such as a CPU 31, a position calculation circuit 32, a memory CTL (controller) 35, and a ROMCTL (controller) 36 connected via a bus 48. In addition, the component which SoC50 has is not restricted to these.

  The ASIC / FPGA 40 includes an image RAM (Image Random Access Memory) 37, a DMAC (Direct Memory Access Controller) 38, a rotator 39, an interrupt controller 41, a sensor I / F 42, and print / sensor timing connected via a bus 47. A generation circuit 43 and an IJ recording head control circuit 44 are provided. In addition, the component which ASIC / FPGA40 has is not restricted to these.

  The CPU 31 executes firmware (program) or the like developed from the ROM 28 to the DRAM 29, and controls operations of the position calculation circuit 32, the memory CTL (Controller) 35, and the ROMCTL 36 in the SoC 50. It also controls the operations of the ImageRAM 37, DMAC 38, rotator 39, interrupt controller 41, sensor I / F 42, print / sensor timing generation circuit 43, and IJ recording head control circuit 44 in the ASIC / FPGA 40.

  The position calculation circuit 32 calculates the position (coordinate information) of the HHP 20 based on the movement amount detected for each driving cycle of the sensor 30. Strictly speaking, the position of the HHP 20 is the position of the nozzle, but if the position of the sensor 30 is known, the position of the nozzle can be calculated. Note that the position of the sensor 30 is calculated based on, for example, a predetermined origin (for example, printing paper or the upper left corner of the image data 7).

  Further, the position calculation circuit 32 calculates the predicted position of the HHP 20 based on the calculated current position of the HHP 20, the past movement amount for each driving cycle detected by the sensor 30, and the movement direction. For example, the position calculation circuit 32 calculates the predicted position of each nozzle of the HHP 20 for each driving cycle of the IJ recording head 24. That is, the position calculation circuit 32 calculates in advance the predicted position of the HHP 20 at the next ink ejection timing. In this way, it is possible to discharge ink while suppressing a delay with respect to scanning by the user.

  The position calculation unit 52 calculates a current nozzle position and a future nozzle position. The position calculation unit 52 includes a current position calculation circuit 52a and a future position calculation circuit 52b. The current position calculation circuit 52 a calculates the position (coordinate information) of the HHP 20 based on the movement amount detected for each driving cycle of the sensor 30. Specifically, the current position calculation circuit 52 a calculates the current position of the sensor 30 and calculates the position of each nozzle based on the positional relationship with the sensor 30. For example, since each nozzle is located on a line connecting the sensors 30a and 30b, the position coordinates of each nozzle can be calculated from the coordinates of the sensors 30a and 30b.

  The future position calculation circuit 52b calculates the predicted position of each nozzle based on the calculated current nozzle position, the past movement amount of the nozzle measured for each driving cycle detected by the sensor 30, and the movement direction. Calculation is performed for each driving cycle of the IJ recording head 24. Further, the driving cycle detected by the sensor 30 is shorter than the driving cycle of the IJ recording head 24.

  For example, when the driving cycle of the IJ recording head 24 is 16 times in one driving cycle of the sensor 30, the future position calculating circuit 52b calculates the predicted position of each nozzle for 16 times. In this case, the control unit 51 controls the print / sensor timing circuit 43 to adjust the ink ejection timing according to the 16 predicted positions. The calculation method of the current position and the predicted position of the sensor 30 and each nozzle will be described later.

  The memory CTL 35 is an interface with the DRAM 29, requests data from the DRAM 29, sends the acquired firmware to the CPU 31, and sends the acquired image data 7 to the ASIC / FPGA 40.

  The ROMCTL 36 is an interface with the ROM 28, requests data from the ROM 28, and sends the acquired data to the CPU 31 and the ASIC / FPGA 40.

  The DMAC 38 acquires the image data 7 around each nozzle of the IJ recording head 24 via the memory CTL 35 based on the position information calculated by the position calculation circuit 32. That is, the image data 7 around the position where the HHP 20 exists is acquired for the print medium 2.

  The rotator 39 rotates the image data acquired by the DMAC 38 in accordance with the head that ejects ink and the nozzle position in the head. The DMAC 38 outputs the rotated image data to the IJ recording head control circuit 44. For example, the rotator 39 can acquire the rotation angle θ calculated when the position calculation circuit 32 calculates the position, and can rotate the image using the rotation angle θ. Further, the rotator 39 determines whether or not to discharge ink from the nozzle, determines whether or not to discharge ink if there is a target discharge position where ink should be discharged, and determines not to discharge if there is no target discharge position. Do.

  The ImageRAM 37 temporarily stores the image data 7 acquired by the DMAC 38. That is, a certain amount of image data 7 is buffered and read according to the position of the HHP 20.

  The IJ recording head control circuit 44 performs dithering or the like on the image data 7 (bitmap data) to convert the image data 7 into a set of points representing an image with size and density. As a result, the image data 7 becomes data of the ejection position and the dot size. The IJ recording head control circuit 44 outputs a control signal corresponding to the dot size to the IJ recording head drive circuit 23. The IJ recording head drive circuit 23 generates a drive waveform (voltage) using the drive waveform data corresponding to the control signal as described above.

  The sensor I / F 42 communicates with the sensor 30, receives the movement amounts ΔX and ΔY as information from the sensor 30, and stores the values in an internal register. ΔX and ΔY indicate the amount of movement in the X-axis direction and the Y-axis direction of the image displayed on the screen 11 with the screen 11 of the display device 10 shown in FIG.

  The print / sensor timing generation circuit 43 notifies the sensor I / F 42 of the timing for reading information from the sensor 30 and notifies the IJ recording head control circuit 44 of the drive timing. The IJ recording head control circuit 44 controls the IJ recording head drive circuit 23 to discharge ink according to the determination result of whether or not to discharge by the rotator 39. Further, the IJ recording head control circuit 44 can also determine whether or not the ejection nozzle is available for the image data received from the rotator 39.

  The interrupt controller 41 detects that the sensor I / F 42 has completed communication with the sensor 30, and outputs an interrupt signal for notifying the SoC 50 of the completion. The CPU 31 acquires ΔX and ΔY stored in the internal register by the sensor I / F 42 by this interruption. In addition, it has a status notification function for errors and the like.

<Timing chart of Embodiment 1>
FIG. 4 is a diagram illustrating a timing chart of processing performed in the control circuit 25. The horizontal axis is time t, indicating the passage of time from the left side to the right side. Each item of the timing chart will be described.

  “Tim_timer” is an internal trigger for the sensor I / F 42 to read the movement amounts ΔX and ΔY measured by the sensor 30. “TSCYC” is a driving cycle in which the sensor I / F 42 reads the movement amount detected by the sensor 30.

  The print / sensor timing generation circuit 43 transmits tim_timer to the sensor I / F 42 every time tSCYC elapses.

  “Sens_TXD” indicates a time for performing read processing on ΔX measured by the sensor 30. “Sens_RXD” indicates a time for performing read processing on ΔY measured by the sensor 30. After receiving tim_timer, the sensor I / F 42 reads ΔX from the sensor 30 during the processing time of Sens_TXD. Further, after receiving tim_timer, the sensor I / F 42 reads ΔY from the sensor 30 during the processing time of Sens_RXD.

  “REG_SENS_RXD” indicates the time during which the value (ΔX, ΔY) written in the register is recorded. The sensor I / F 42 writes ΔX and ΔY read from the sensor 30 to the register.

  “Sens_int” indicates the timing of interrupt processing issued when the sensor I / F 42 completes reading to the sensor 30. “TSPEAD” indicates the time required to read the sensor 30.

  The sensor I / F 42 issues a sens_int interrupt notification to the CPU 31 when the reading process of the sensor 30 is completed. After receiving the sens_int interrupt notification, the CPU 31 reads the movement amounts ΔX and ΔY from the register.

  The current position calculation circuit 52a calculates the current position of the sensor 30 based on the previous position of the sensor 30 and the movement amounts ΔX and ΔY. For example, as will be described later, the current position calculation circuit 52a calculates the current position of the sensor 30 by calculating the parallel movement component and the rotation component from the movement amounts ΔX and ΔY. Subsequently, the current position calculation circuit 52a calculates each nozzle position arranged on the line connecting the sensor 30a and the sensor 30b based on the positional relationship with the sensor 30a and the sensor 30b.

  The future position calculation circuit 52b calculates the predicted position of each nozzle for the number of times that ejection is determined for each drive cycle tSCYC. The driving cycle tSCYC indicates a cycle for acquiring nozzle position information. The driving cycle tSCYC corresponds to a time interval at which tim_timer is transmitted, for example. For example, assuming that ink is ejected 10 times during the driving cycle tSCYC, the future position calculation circuit 52b calculates the predicted position of the sensor 30 up to 10 times ahead.

  Moreover, although the future position calculation circuit 52b demonstrated calculating the estimated position of each nozzle for the frequency | count of discharge determination for every drive period tSCYC, it is not limited to this. The future position calculation circuit 52b may calculate the predicted position of each nozzle at a predetermined cycle shorter than the drive cycle tSCYC. For example, the future position calculation circuit 52b may calculate the predicted position of each nozzle every two drive cycles (drive cycle “tJCYC” described later) or more of the IJ print head 24.

  “TCAL” is an elapsed time from the start of calculation of the current position of each nozzle to the end of calculation of the predicted position. The future position calculation circuit 52b completes the calculation of the plurality of predicted positions of each nozzle within the time tCAL.

  Moreover, although the method of calculating the predicted position of a nozzle for every nozzle was demonstrated, it is not limited to this. For example, the future position calculation circuit 52b calculates the predicted position of each sensor 30 for the number of times that ejection is determined for each drive cycle tSCYC, and calculates the predicted position of each nozzle from the calculated predicted position of each sensor 30. May be. For example, the nozzles are arranged at equal intervals on a line connecting the sensor 30a and the sensor 30b. For this reason, if the future position calculation circuit 52b calculates the predicted positions of the sensor 30a and the sensor 30b, it can calculate the predicted position of each nozzle from the positional relationship with the sensor 30a and the sensor 30b.

  “REG_HEAD_POS” indicates the time during which the value (ΔX, ΔY) written in the register of the rotator 39 is recorded. The future position calculation circuit 52b writes the predicted position of each nozzle to the register of the rotator 39. The register of the rotator 39 can store, for example, 16 predicted positions of each nozzle, and stores the predicted positions of each nozzle in a FIFO (First In First Out) format.

  The rotator 39 reads the information on the predicted position stored in the register in the order of storage, and acquires the predicted position of each nozzle from the information on the predicted position of the sensor 30.

  The rotator 39 reads the image data corresponding to the calculated predicted position of each nozzle from the external memory and stores it in the ImageRAM 37.

  “TMEM” is the time required to read the image data at the first ink discharge position after the predicted position of each nozzle is stored in the ImageRAM 37. “TJCYC” is the drive cycle of the IJ recording head 24. “Tim_enctrg” is a trigger for the driving cycle tJCYC of the IJ recording head 24, and ink is ejected each time a trigger for the driving cycle tJCYC is generated.

  The rotator 39 compares the position where the nozzle is scheduled to be ejected with the coordinates of the image data, and determines whether or not to eject ink. When it is determined that the ejection condition is satisfied, the rotator 39 transfers the image data to the IJ recording head control circuit 44 according to the cycle of tim_enctrg.

  The predicted position of each nozzle is calculated by the rotator 39 for the number of times ink is determined to be ejected within the drive cycle tSCYC in which the sensor 30 is read (for the number of times of the drive cycle tJCYC), and it is determined whether or not to eject ink. Is done. That is, the rotator 39 determines whether or not to discharge ink every driving cycle tJCYC of the IJ recording head 24.

  “Vcom” indicates a driving waveform of the IJ recording head 24. “TDRV” indicates the time for each drive waveform. For example, “tDRV” is the driving time of the piezo element. In the case of the first embodiment, “tDRV” is relatively short, and the drive waveform of the IJ recording head 24 is intermittent. “TJet” indicates the time from when the drive waveform is generated until ink reaches the paper. “TPREDICT” indicates the time from when the position information of the sensor 30 is read to when the ink first lands.

<Timing chart of reference example>
FIG. 5 is a diagram illustrating a timing chart of the image processing of the reference example. As a difference from the first embodiment, in the reference example, regarding “Vcom”, “tDRV” is relatively long, the drive waveform of the IJ recording head 24 is continuous, and the ejection time for one time is relatively long. long.

  In the reference example, the predicted position of each nozzle is calculated once within the driving cycle tSCYC in which the sensor 30 is read, and it is determined once whether or not ink is to be ejected. That is, the area printed on the paper at a time is large, and it is determined whether or not ink is ejected to the print area. The determination is executed once for each cycle tSCYC in which the sensor 30 is read. . When the print area overlaps the non-ejection area, ejection from the nozzle is stopped.

<Positional relationship between sensor and nozzle>
FIG. 6 is a diagram illustrating a positional relationship between the sensor 30 and the nozzle. FIG. 6 is a diagram for explaining detection of a rotation component by a sensor 30. FIG. 6A represents the bottom surface of the HHP 20. FIG. 6B shows the IJ recording head 24. Hereinafter, a method for calculating the position of each nozzle from the position of the sensor 30 will be described with reference to FIGS.

  The HHP 20 of this embodiment has two or more sensors 30. Since the HHP 20 includes two or more sensors 30, the rotation angle θ can be detected even if the sensors 30 rotate on the print medium. For example, in FIG. 6A, two sensors 30a and 30b are arranged apart from each other in the nozzle arrangement direction. The length between the two sensors 30a and 30b is a distance L. The rotation angle θ can be calculated using the difference in the amount of movement of the sensors 30a and 30b in the X-axis direction or the Y-axis direction and the distance L.

  Also, the longer the distance L, the smaller the minimum rotation angle θ that can be detected, and the smaller the position error of the HHP 20, so the longer the distance L, the better.

  The distances from the sensor 30a to the IJ recording head 24 are distances a and b, respectively. The distance a is equal to the distance b. Further, as shown in FIG. 6B, the distance from the tip of the IJ recording head 24 to the first nozzle is a distance d, and the distance between adjacent nozzles is a distance e. The values of the distances a to e are stored in advance in the ROM 28 or the like.

  The position calculation circuit 32 can calculate the position of each nozzle from the positional relationship with the sensor 30 by calculating the position of the sensor 30.

  In this embodiment, the horizontal direction to the print medium 2 is set as the X axis, and the vertical direction is set as the Y axis. On the other hand, the sensor 30 outputs a position on the following coordinate axes (X ′ axis, Y ′ axis). That is, a nozzle arrangement direction (a direction parallel to a line passing through the two sensors 30a and 30b) is a Y ′ axis, and a direction orthogonal to the Y ′ axis is an X ′ axis.

  FIG. 7 is a diagram for explaining a sensor position calculation method. In FIG. 7, the IJ recording head 24 before movement is shown on the left side, and the IJ recording head 24 after movement is shown on the right side. Sensors 30 a and 30 b are arranged at both ends of the IJ recording head 24. The IJ recording head 24 moves in the upper right direction. Further, the axis passing through the sensor 30a and the sensor 30b of the IJ recording head 24 is turned by dθ in the clockwise direction.

The initial position of the sensor 30a is (X ₀ , Y ₀ ), the initial position of the sensor 30b is (X ₁ , Y ₁ ), and the distance from the sensor 30a to the sensor 30b is L. Further, the rotational component of the axis passing through the sensor 30a and the sensor 30b before and after the movement is dθ, and the parallel movement component in the X-axis direction of the sensor 30a before and after the movement is ΔX ₀ , the parallel in the Y-axis direction Let the moving component be ΔY ₀ . Further, the movement component in the X-axis direction detected by the sensor 30a before and after movement is referred to as dx _S0 , and the movement component in the Y-axis direction is defined as dy _S0 . Note that the movement components detected by the sensor 30a include dx _S0 and dy _S0 that include rotational components of the axis passing through the sensors 30a and 30b.

The position calculation circuit 32 calculates a rotation component and a parallel movement component from dx _S0 . The position calculation circuit 32 calculates the rotation component dθ based on the following mathematical formula.

The position calculation circuit 32 calculates the parallel movement components dX ₀ and dY ₀ based on the following mathematical formula.

dX ₀ = dx _{S 0} × cos θ + dy _{S 0} × sin θ
dY ₀ = −dx _{S 0} × sin θ + dy _{S 0} × cos θ (1)
FIG. 8 is a diagram for explaining calculation of the leading nozzle position. Nozzles 24a to 24f are arranged on a line segment connecting the sensor 30a and the sensor 30b. The position calculation circuit 32 calculates the exact position of each nozzle from the positional relationship between the sensors 30a and 30b and each nozzle.

When the distance from the sensor 30a to the IJ recording head 24 is a, the distance from the sensor 30a side end of the IJ recording head 24 to the head nozzle 24a is d, and the distance between the nozzles is e, the position calculation circuit 32 Finds the position (NZL ₁ _X, NZL ₁ _Y) of the _first nozzle 24a in the array by the following equation. Further, the position calculation circuit 32 obtains the rear nozzle 24f in the same manner as the nozzle 24a.

NZL ₁ _X = X ₀ − (a + d) × sin θ
NZL ₁ _Y = Y ₀ − (a + d) × cos θ (2)
FIG. 9 is a first diagram for explaining the calculation of the position of the nozzle located in the middle between the head and tail nozzles. The position calculation circuit 32 obtains the position of the Nth nozzle 24N (24b to f) from the head that is between the head and tail nozzles based on the positional relationship with the head and tail nozzles using the following formula.

NZLN_X = XS + {(XE-XS) / (E-1)} * N
NZLN_X = YS + {(YE−YS) / (E−1)} × N (3)
<Pixel conversion of nozzle position coordinates>
FIG. 10 is a diagram for explaining pixel conversion in units of position coordinates of each nozzle. FIG. 10 shows the position of the IJ recording head 24 when the IJ recording head 24 is scanned in the lower right direction. The solid line figure is the current position of the IJ recording head 24, and the dotted line figure is the position of the IJ recording head 24 in the past for one drive cycle (tJCYC) of the IJ recording head 24. The IJ recording head 24 includes nozzles 24a to 24n. The nozzle 24a is the first nozzle in the nozzle array, and the nozzle 24n is the last nozzle in the nozzle array.

  For example, the position calculation circuit 32 calculates the position coordinates 24a (1) to (5) of the nozzle 24a that are predicted based on the position coordinates of the current and past nozzles 24a. Similarly, the position calculation circuit 32 calculates the position coordinates 24n (1) to (5) of the nozzle 24b that are predicted based on the position coordinates of the current and past nozzles 24n. Note that the position calculation circuit 32 similarly calculates position coordinates for the nozzles between the nozzles 24a and 24n.

  Predicted position coordinates 24 a (1) to (5) of the nozzle 24 a are position coordinates that are expected to reach every driving cycle (tJCYC) of the IJ recording head 24. The same applies to the position coordinates 24b (1) to (5) of the nozzle 24b.

In the following, the position coordinates of the nozzle 24a in the past for one drive cycle (tJCYC) are expressed as (d_nzl ₁ _x, d_nzl ₁ _y), and the current position coordinates are expressed as (c_nzl ₁ _x, c_nzl ₁ _y). The predicted position coordinates of the nozzle 24a are set to (r ₀ _nzl ₁ _x, r ₀ _nzl ₁ _y), (r ₁ _nzl ₁ _x, r ₁ _nzl ₁ _y), (r ₂ ) in each drive cycle (tJCYC). _{_nzl 1 _x, r 2 _nzl 1} _y), shall be expressed as _{(r 3 _nzl 1 _x, r} 3 _nzl 1 _y), (r 4 _nzl 1 _x, r 4 _nzl 1 _y).

As for the head of the counting from the nozzles 24a of the n-th nozzle 24n, 1 driving cycle (tJCYC) minutes past coordinates and _{(d_nzl n _x, d_nzl n _y} ) is expressed as the current position coordinates (C_nzl _n _x, referred to as c_nzl _n _y). The position coordinates of the expected nozzle 24a for each drive cycle (tJCYC), sequentially _{(r 0 _nzl n _x, r} 0 _nzl n _y), (r 1 _nzl n _x, r 1 _nzl n _y), (r 2 _{_nzl n _x, r 2 _nzl n} _y), it shall be expressed as _{(r 3 _nzl n _x, r} 3 _nzl n _y), (r 4 _nzl n _x, r 4 _nzl n _y).

  When the coordinates of the nozzles on the actual print medium are expressed in μm units, they can be converted into pixel units by the following mathematical formula.

Nozzle coordinate [pixel] = nozzle coordinate [μm] × resolution [dpi] ÷ 25400 (1)
For example, when the current position coordinates (NZL ₁ _X, NZL ₁ _Y) of the nozzle 24a and the nozzle 24n are converted into pixels, the following is performed. The resolution is 2400 [dpi].

c_nzl ₁ _x = NZL ₁ _X × 2400 [dpi] ÷ 25400
c_nzl ₁ _y = NZL ₁ _Y × 2400 [dpi] ÷ 25400
c_nzl _n _x = NZL _n _X × 2400 [dpi] ÷ 25400
c_nzl _n _y = NZL _n _Y × 2400 [dpi] ÷ 25400
<Judgment of discharge>
FIG. 11 is a diagram for explaining the ejection determination. Nozzles 24 a to 24 d are arranged in the IJ recording head 24. The rotator 39 determines whether or not to eject ink individually to each of the nozzles 24a to 24d. When the rotator 39 determines that the ejection condition is satisfied, the rotator 39 transmits the image data to the IJ recording head control circuit 44. The rotator 39 compares the coordinates of the predicted position of the nozzle and the coordinates of the target discharge position (dischargeable area), and determines that the discharge condition is satisfied if they match.

  The rotator 39 may determine that the discharge condition is satisfied when a predetermined range near the nozzles 24a to 24d is set as an allowable error range and the target discharge position is included in the allowable error range of the nozzles 24a to 24d. Thereby, even when the scanning speed of the HHP 20 is high, the timing at which the nozzle position coordinates coincide with the coordinates of the target ejection position is missed, and non-ejection is prevented.

  For example, even if the predicted position coordinates of the nozzle 24a in FIG. 11 deviate from the target discharge position, if the target discharge position is included within the allowable error range from the predicted position coordinates, the rotator 39 may The determination result to be ejected may be transmitted to the IJ head control circuit 44 to eject ink. The allowable error range is set to a predetermined range of 1 cell or less, for example.

  Also, when the allowable error range is set to be large, the timing at which the nozzle position coordinates coincide with the target ejection position coordinates is less likely to be missed, and non-ejection is less likely to occur, but the displacement of the ink ejection position increases. On the other hand, when the allowable error range is set small, the deviation of the ink ejection position is small, but the timing at which the nozzle position coordinates coincide with the target ejection position coordinates is often missed, and non-ejection tends to occur. Therefore, the allowable error range is appropriately adjusted according to the application for which the HHP 20 is used.

<Flow of image forming process>
FIG. 12 is a flowchart illustrating the image forming process. The left side of FIG. 12 shows the operation flow of the user, and the right side of FIG. 12 shows the operation flow on the control circuit 25 side such as the SoC 50 and the ASIC / FPGA 40.

  When the user depresses the power source of the HHP 20 (step S10), the power source is supplied to the control circuit 25 side, and the control circuit 25 starts operation (step S20). The SoC 50 executes initialization of each device (step S21). The SoC 50 determines whether or not the initialization has been completed (step S22). If the initialization has not been completed (step S22 No), the determination process is performed again after a predetermined time. When the initialization is completed (Yes in step S22), the SoC 50 turns on the LED lamp (step S23) and notifies the user of the completion of the initialization process.

  When a print image is selected on an image data output device such as a smartphone or tablet terminal (step S11), the image data output device generates a print JOB (step S12). For example, a print job is generated by an application or printer driver installed in the image data output device. The image data output device transmits the print job and the selected print image to the HPP 20 by wireless communication.

  When receiving the image data, the SoC 50 notifies the user by blinking the LED (step S24).

  When the initial position of the printing process is determined by the user (step S13) and the print start button is pressed (step S14), the printing process is started by the HHP 20. For example, the HHP 20 is placed by the user along the four corners of the printing paper as the initial position. Subsequently, the HHP 20 is scanned freehand by the user (step S15).

  The SoC 50 notifies the sensor I / F 42 to acquire the position information of the HHP 20. The sensor 30 acquires position information and stores the acquired position information in the internal memory (step S26). The sensor I / F 42 reads the internal memory of the sensor 30 and acquires position information stored in the internal memory (step S25). The sensor I / F 42 stores the first read position in the memory as an initial position (step S27). For example, the sensor I / F 42 stores the read initial position in the memory as the origin (0, 0).

  The print / sensor timing generation circuit 43 measures the timing of reading to the sensor 30 with a counter, and if it is not the set sensor read time (No in step S29), it waits until the sensor read time is reached. The print / sensor timing generation circuit 43 reads position information from the memory of the sensor 30 when the set sensor read time is reached (step S29 Yes) (step S30).

  The current position calculation circuit 52a calculates the current position of the sensor 30 from the previously calculated position of the sensor 30 and the movement amounts ΔX and ΔY read this time, and stores the current position of the sensor 30 in the memory 29 (step S31). ).

  The current position calculation circuit 52a calculates the current position of the nozzle from the positional relationship with the sensor 30, and stores the current position of the nozzle in the memory 29 (step S32).

  The future position calculation circuit 52b calculates the predicted position of each nozzle for the number of times of determining ink ejection within the read cycle (drive cycle tSCYC) of the sensor 30 (the number of drive cycles tJCYC) and stores it in the memory 29 ( Step S33).

  In addition to the method described in steps S31 to S33, the predicted position of each nozzle may be calculated as follows. The future position calculation circuit 52b calculates the predicted position of each sensor 30 by the number of times ink ejection is determined within the read cycle of the sensor 30. Subsequently, the future position calculation circuit 52b may calculate a predicted position of each nozzle for the number of ejection determinations based on the positional relationship with the sensor 30.

  The rotator 39 reads the image data around each nozzle from the external memory based on the predicted position of each nozzle, and stores it in the ImageRAM 37 (step S34). The rotator 39 compares the image data stored in the ImageRAM 37 with the predicted position of each nozzle (step S35), and determines whether or not the ejection condition is satisfied (step S36). For example, the rotator 39 determines whether or not image data is included in the allowable error range from the nozzle position as the ejection condition.

  When the discharge condition is not satisfied (No at Step S36), the rotator 39 stands by until a position that satisfies the discharge condition. When the discharge condition is satisfied (Yes at Step S36), the rotator 39 outputs the image data to the IJ recording head 24, and discharges the ink onto the print medium (Step S37).

  The SoC 50 determines whether all image data has been output (step S38). The SoC 50 returns to the process of step S29 when all the image data is not output (step S38 No). On the other hand, when all the image data has been output (Yes at Step S38), the SoC 50 notifies the user of printing completion by turning off the LED (Step S39). Even before all the image data is output, if the processing completion button is pressed by the user, the HHP 20 may complete the processing halfway.

<First example of predicted position calculation (equal speed)>
FIG. 13 is a diagram for explaining the calculation of the predicted nozzle position when the HHP 20 scans at a constant speed. The horizontal axis is time t, indicating the passage of time from the left side to the right side. The HHP 20 scans on the paper at a constant speed, and the movement amounts ΔX and ΔY increase in proportion to the time t. The items in the timing chart are the same as those in FIG.

  The print / sensor timing generation circuit 43 transmits tim_timer to the sensor I / F 42 every time 1 [ms] of tSCYC elapses.

  After receiving tim_timer, the sensor I / F 42 reads ΔX from the sensor 30 during the processing time of Sens_TXD. Further, after receiving tim_timer, the sensor I / F 42 reads ΔY from the sensor 30 during the processing time of Sens_RXD. The time tSPEAD required for reading the sensor 30 is 90 [um]. Subsequently, the sensor I / F 42 writes the movement amounts ΔX and ΔY read from the sensor 30 to the register.

  The sensor I / F 42 issues a sens_int interrupt notification to the CPU 31 when the reading process of the sensor 30 is completed. After receiving the sens_int interrupt notification, the CPU 31 reads the movement amounts ΔX and ΔY from the register.

The current position calculation circuit 52a calculates the current position of the sensor 30 based on the previous position of the sensor 30 and the movement amounts ΔX and ΔY. For example, as will be described later, the current position calculation circuit 52a calculates the current position of the sensor 30 by calculating the parallel movement component and the rotation component from the movement amounts ΔX and ΔY. Subsequently, the current position calculation circuit 52 a calculates the current positions (c_nzl ₁ _x, c_nzl ₁ _y) to (c_nzl _n _x, c_nzl _n _y) of the nozzles 24 a to 24 _n from the positional relationship with the sensor 30.

The future position calculation circuit 52b calculates the predicted position of the nozzle for the number of times of the driving cycle tJCYC within the driving cycle tSCYC (for the number of times of ejection determination). Since the HHP 20 scans the paper at a constant speed, the future position calculation circuit 52b calculates the predicted position coordinates of each nozzle for each drive cycle tJCYC by proportional calculation. E.g., x-coordinate r _i _nzl ₁ _x nozzle 24a after the next i driving cycle from the current position is calculated by the following equation.

Further, the x coordinate r _i —nzl _n —x of the nozzle 24 _n after the next i driving cycle from the current position is calculated by the following mathematical formula.

Moreover, the y coordinate of the nozzle 1 and the nozzle n can be similarly calculated by the above method.

  As described above, the future position calculation circuit 52b calculates the predicted position for the number of times of the drive cycle tJCYC for each nozzle, as in the mathematical expressions 1 and 2.

An example of calculation using the mathematical formula 1 will be described. Number of ejections jet_num = 5 in 1 driving cycle, d_nzl_x = 0, when the C_nzl_x = 2, the future position calculation circuit 52b is the x coordinate r _i _nzl _n _x of the nozzles after i driving cycle, the formula in Formula 2 Is calculated as follows.

i = 1: 0 + (2 * 2) + (2 * 3/5) = 5.2
i = 2: 0 + (2 * 2) + (2 * 4/5) = 5.6
i = 3: 0 + (2 * 2) + (2 * 4/5) = 6.0
i = 4: 0 + (2 * 2) + (2 * 4/5) = 6.4
i = 5: 0 + (2 * 2) + (2 * 4/5) = 6.8
Note that the future position calculation circuit 52b also calculates the y-coordinates r _i _nzl _n _y of the nozzle after the i driving cycle in the same manner as described above.

  The rotator 39 compares the calculated predicted position of the nozzle with the target ejection position, and causes the IJ recording head 24 to eject ink when the target ejection position is within the allowable error range from the predicted position of the nozzle.

  In this way, by calculating the position of each nozzle for each drive cycle of the IJ recording head 24, it is possible to reduce non-ejection and control to eject ink more reliably in the ejectable area.

[Embodiment 2]
<Calculation of operation amount using PID control>
By using the PID control algorithm, the future position calculation circuit 52b can calculate the position coordinates of each nozzle even when the acceleration of the scanning speed of the HHP 20 changes. When PID control is used, the operation amount is defined by the following mathematical formula. K _p is a proportional element parameter, K _i is an integral element parameter, K _d is a derivative element parameter, and e is a deviation. The operation amount is a movement amount of the HHP 20 for each driving cycle tJCYC in consideration of acceleration.

The future position calculation circuit 52b calculates the proportional term P, the integral term I, and the differential term D as follows when the proportional element is P, the integral element is I, and the differential element is D (operation amount = P + I + D). To do.

P: P = K _p × deviation The deviation indicates the difference between the previous nozzle position coordinates and the current nozzle position coordinates. That is, the deviation is the moving distance of the nozzle.

I: I = K _i × accumulated value × period accumulated deviation value = {(current deviation + previous deviation) / 2} × period The period indicates a discharge time interval. That is, one drive cycle (tJCYC) of the IJ recording head 24 is shown.

D: D = K _d × (current deviation−previous deviation) / cycle <various parameter values used for PID control>
Parameters used in the PID control as described above, a proportional element parameters K _p, an integral element parameters K _i, which is one third differentiating element parameter K _d.

  Each parameter value may be set in advance for each speed, and each parameter may be changed according to a change in the scanning speed of the HHP 20.

FIG. 14 is a diagram illustrating an example of PID parameter values set for each speed. V [mm / s] indicates the speed per second of HHP20. For example, when the scanning speed of the HHP 20 is 0 to 100 [mm / s], K _p = 1.0, K _i = 0.0, K _d = 0.0 are set, and the differential and integral terms The value is 0, and only the value of the proportional term is reflected in the manipulated variable. This is because when the scanning speed of the HHP 20 is low, the HHP 20 is often scanned at a constant speed.

Further, when the scanning speed of the HHP 20 is 100 to 200 [mm / s], K _p = 1.0, K _i = 0.0, K _d = 0.5 are set, and the value of the proportional term is 1. , The value of the differential term is ½, and the value of the integral term is 0. This is because when the speed of the HHP 20 is slightly low, the HHP 20 is often scanned with equal acceleration.

  Each parameter is also set when the speed is 200 to 300 [mm / s] or 300 to 400 [mm / s]. When the scanning speed of the HHP 20 is high, the speed is likely to change, so the value of the proportional element parameter is set low.

  Each parameter value may be recorded in the ROM 28 in advance, for example. The future position calculation circuit 52b may acquire each parameter from the ROM 28 according to the scanning speed calculated from ΔX and ΔY measured by the sensor 30 and use it for PID control.

  As described above, the parameter values used for the proportional term, the integral term, and the differential term are set in advance for each speed, and the operation amount is calculated by properly using each parameter value according to the scanning speed, whereby the future position calculation circuit 52b. The prediction accuracy of the predicted position can be improved.

<Second example of predicted position calculation (with speed change)>
FIG. 15 is a diagram for explaining the calculation of the predicted nozzle position when the scanning speed of the HHP 20 changes. The horizontal axis is time t, indicating the passage of time from the left side to the right side. The HHP 20 scans on the paper at a constant speed, and the movement amounts ΔX and ΔY increase in proportion to the time t. The items in the timing chart are the same as those in FIG.

  The print / sensor timing generation circuit 43 transmits tim_timer to the sensor I / F 42 every time 1 [ms] of tSCYC elapses.

  After receiving tim_timer, the sensor I / F 42 reads ΔX from the sensor 30 during the processing time of Sens_TXD. Further, after receiving tim_timer, the sensor I / F 42 reads ΔY from the sensor 30 during the processing time of Sens_RXD. The time tSPEAD required for reading the sensor is 90 [um]. Subsequently, the sensor I / F 42 writes ΔX and ΔY read from the sensor 30 to the register.

  The sensor I / F 42 issues a sens_int interrupt notification to the CPU 31 when the reading process of the sensor 30 is completed. After receiving the sens_int interrupt notification, the CPU 31 reads the movement amounts ΔX and ΔY from the register.

The current position calculation circuit 52a calculates the current position of the sensor 30 based on the previous position of the sensor 30 and the movement amounts ΔX and ΔY. For example, the current position calculation circuit 52a calculates the current position of the sensor 30 by calculating the parallel movement component and the rotation component from the movement amounts ΔX and ΔY. Subsequently, the current position calculation circuit 52 a calculates the current positions (c_nzl ₁ _x, c_nzl ₁ _y) to (c_nzl _n _x, c_nzl _n _y) of the nozzles 24 a to 24 _n from the positional relationship with the sensor 30.

  The future position calculation circuit 52b calculates the predicted position of each nozzle for the number of times that ejection is determined for each drive cycle tSCYC. Since the scanning speed of the HHP 20 changes, the future position calculation circuit 52b calculates the predicted position coordinates of each nozzle for each driving cycle tSCYC by PID control.

For example, the x coordinate r _i —nzl ₁ —x of the nozzle 1 after the next i driving cycle from the current position is calculated by the following equation.

Further, the x coordinate r _i —nzl _n —x of the nozzle n after the next i driving cycle from the current position is calculated by the following mathematical formula.

Moreover, the y coordinate of the nozzle 1 and the nozzle n can be similarly calculated by the above method.

  Thus, even when the scanning speed of the HHP 20 changes by calculating the position of each nozzle using PID control, the prediction accuracy of each nozzle can be improved.

The HHP 20 is an example of an image forming apparatus. The sensor I / F 42 is an example of a position information acquisition unit. The future position calculation circuit 52b is an example of a position prediction unit. The driving cycle tSCYC is an example of a cycle for acquiring position information. The drive cycle tJCYC is an example of a discharge cycle. The rotator 39 is an example of a target discharge position acquisition unit. The proportional element parameter _Kp is an example of a first coefficient. The integral element parameter K _i is an example of a second coefficient. The differential element parameter _Kd is an example of a third coefficient. Acceleration is an example of speed deviation.

10 Display Device 23 IJ Recording Head Drive Circuit 25 Control Circuit 26 OPU
28 ROM
29 Memory (DRAM)
30a, 30b Sensor 31 CPU
32 position calculation circuit 35 memory CTL
36 ROMCTL
37 ImageRAM
38 DMAC (CACHE)
39 Rotator 40 ASIC / FPGA
41 Interrupt controller 42 Sensor I / F
43 Print / Sensor Timing Generation Circuit 44 IJ Recording Head Control Circuit 45, 46 Bus

JP 2006-305812 A

Claims (10)

An image forming apparatus for forming an image on a medium,
A nozzle for discharging an image forming material;
Position information acquisition means for acquiring position information of the nozzle on the surface of the medium;
Position prediction means for determining predicted position information indicating a next discharge position of the nozzle from past position information of the nozzle and current position information of the nozzle, and
The image forming apparatus, wherein the position predicting unit determines the predicted position information of the nozzle in a cycle shorter than a cycle of acquiring the position information of the nozzle.   2. The position prediction unit determines prediction position information for the number of times that the image forming material is determined to be ejected each time the position information acquisition unit acquires the position information of the nozzle. Image forming apparatus.   A target for causing the nozzle to eject an image forming material when a target ejection position for ejecting the image forming material on the surface of the medium is acquired and the target ejection position is within an allowable error range from the determined predicted position information. The image forming apparatus according to claim 1, further comprising an ejection position acquisition unit.   The position predicting unit determines the predicted position information of the nozzle based on current position information of the image forming apparatus and position information one cycle before a period for acquiring the position information of the nozzle. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   5. The image according to claim 4, wherein the position predicting unit receives a change in a first coefficient that multiplies the speed of the image forming apparatus, and determines predicted position information of the nozzle based on a calculation result. Forming equipment.   The position predicting unit further determines the predicted position information of the nozzle by using a cumulative value of the speed deviation of the image forming apparatus and a change amount of the speed deviation of the image forming apparatus. Item 6. The image forming apparatus according to Item 4 or 5.   The position predicting unit receives a change in a second coefficient that is multiplied by a cumulative value of the speed deviation of the image forming apparatus and a third coefficient that is multiplied by a change amount of the speed deviation of the image forming apparatus. 6. The image forming apparatus according to claim 5, wherein the predicted position information of the nozzle is determined based on the information.   The position predicting means stores a value corresponding to the speed in each of the first coefficient, the second coefficient, and the third coefficient, and determines the predicted position information of the nozzle based on a calculation result. The image forming apparatus according to claim 7. A method executed by an image forming apparatus,
Obtaining position information on the surface of the print medium of the nozzle for discharging the image forming material;
Determining predicted position information indicating a next discharge position of the nozzle from a past position information of the nozzle and a current position information of the nozzle at a cycle shorter than a cycle of acquiring the position information of the nozzle; The image forming apparatus executes the above. A program to be executed by an image forming apparatus,
Obtaining position information on the surface of the print medium of the nozzle for discharging the image forming material;
Determining predicted position information indicating the next discharge position of the nozzle from the past position information of the nozzle and the current position information of the nozzle in a cycle shorter than the cycle of acquiring the position information of the nozzle; , Which causes the image forming apparatus to execute.