JP2005246669A - Striking position measuring method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a striking position measuring method whereby only a deviation amount resulting from a recording head whose feeding error caused by a carriage or a moving means for a recording medium is eliminated can be extracted, and moreover a deviation amount resulting from an arrangement manner of a recording medium can be eliminated by measuring a striking position deviation by the same apparatus as an apparatus which prints an evaluation pattern, and to provide a striking position measuring apparatus. <P>SOLUTION: This method comprises: a position detection process of detecting a position of a recording head; a process of performing image recording onto the recording medium on the basis of the position in a main scanning direction of the recording head detected in the position detection process; and a process of exchanging the recording head with an image capturing means for capturing the image on the recording medium at a mounting position of the recording head in the carriage, and of detecting a striking position of ink dots discharged from a plurality of nozzles from a captured image obtained by the image capturing means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for measuring the landing position of ink dots drawn on a recording medium.

Conventionally, the landing position is measured by the following procedure.
(1) An evaluation pattern is recorded on a recording medium with an inkjet printer.
(2) Take this recording medium to a device different from the ink jet printer and measure the landing position.

  First, the ink jet printer (1) will be described.

  FIG. 10 shows a schematic diagram of an ink jet printer using a conventional color ink jet recording system.

  In the ink jet printer of FIG. 10, when recording (drawing) an image on the recording medium 140 on the platen 106, the motor 103 is first driven, and the carriage 102 is moved to the position of the origin sensor 108 by the driving belt 109, and then , While moving the carriage 102 in the forward direction indicated by the arrow X1, black BK, cyan C, magenta M, and yellow Y inks are recorded from the predetermined positions according to the input image data, respectively. A predetermined image is recorded by discharging from the nozzle 123.

  When the recording of an image for a predetermined length set in advance is finished, the carriage 102 stops moving in the forward direction indicated by X1, and then the carriage 102 is moved in the backward direction opposite to the forward direction indicated by the arrow X2. While moving, the carriage 102 is returned to the start position (the position of the origin sensor 108) for the next image recording scan. While moving the carriage 102 in the backward direction, the feed rollers 106 and 110 are rotated by the feed motor 107, and the recording medium 140 is moved in the main scanning direction by a length corresponding to the width of the image recorded by the recording heads 120 to 123. It is conveyed in the sub-scanning direction (arrow Y direction) that is a direction orthogonal to each other.

  An image is recorded on the recording medium 140 while moving the carriage 102 in the main scanning direction as described above, and then the operation of transporting the recording medium 140 by one band width is repeated to complete image recording of a color image.

  In the above description, the image recording operation in one direction of the forward direction has been described as an example, but bidirectional image recording operation in the forward direction and the backward direction is also possible, and in this case, image recording in the forward direction was performed. Thereafter, if the recording medium 140 is transported in the sub-scanning direction by the length corresponding to one band width in which the images are recorded by the recording heads 120 to 123, and the image recording is performed in the backward direction, the forward and backward directions are performed. Images can be recorded. In the figure, reference numerals 100 and 101 denote feed second rollers, and 111 denotes a medium detection sensor.

  Further, the ink ejection timing from each nozzle of the recording heads 120 to 123 is generated with reference to an output signal from a linear encoder described later. The position of each recording head 120 to 123 is detected by a linear encoder, and this linear encoder can detect the position with an accuracy corresponding to a required resolution (for example, 1200 dpi). Yes. Therefore, in an inkjet printer having such a linear encoder, the image recording resolution and the image recording accuracy are determined by the position detection signal output from the linear encoder.

  For this reason, in the ink jet printer as described above, the recording heads 120, 121,... Are related to the image data corresponding to the same pixel from the positional information from the linear encoder and the relative positions of the recording heads 120, 121, 122, 123. Since multicolor image recording is realized by superimposing black (BK), cyan (C), magenta (M), and yellow (Y) inks ejected from 122 and 123, the linear encoder The position information has a great influence on the image quality.

  Currently, a magnetic encoder and an optical encoder shown in FIG. 10 are generally used as the linear encoder used in the ink jet printer as described above. For example, a magnetic linear encoder is a metal linear scale plate formed with a large number of magnetized locations on a scale unit, and a magnet that is mounted on the carriage 102 and detects magnetism at the magnetized locations of the linear scale plate. And a sensor unit.

  On the other hand, as shown in FIG. 10, the optical linear encoder 130 is a scale with a band-shaped scale grid formed by alternately printing light reflecting portions and non-reflecting portions in units of scale on a glass having a low expansion coefficient. 131 and a sensor unit 132 that receives light applied to the scale 131 and receives reflected light from the scale 131. Examples of the sensor unit 132 include a light projecting unit made up of an LED or a laser light source mounted on the carriage 102 and a light receiving unit made up of a photodiode, a phototransistor, or the like (light projecting / receiving device). Commonly used.

  In any linear encoder using either a magnetic type or an optical type, the home position is the reference position, and the reading pulse signal from the sensor unit that is output in units of linear scales as the main scanning carriage 102 moves is used. The position information of the carriage 102 can be obtained by counting up / down by an encoder counter and reading the count value.

  The evaluation pattern is recorded by the ink jet printer having improved image quality as described above.

  Next, a conventional landing position measuring apparatus will be described with reference to the schematic diagram of FIG.

  In the landing position measuring apparatus of FIG. 17, reference numeral 140 denotes a recording medium drawn by the ink jet printer, and 2 denotes a microscope for optically expanding an evaluation pattern on the recording medium 140. Here, the microscope 2 is fixed by a height adjusting mechanism (not shown), and is configured so that the interval between the recording medium 140 and the microscope 2 can be adjusted. 3 is a CCD camera for converting the optical image of the evaluation pattern magnified by the microscope 2 into an electrical video signal, 4 is a light source for illuminating the recording medium 140, and 5 is the light from the light source 4 up to the recording medium 140. A light guide 6 that guides the video signal from the CCD camera 3 and processes an image processing unit for measuring the position and shape of dots, and 7 displays an image of the recording medium 140 captured by the CCD camera 3. The monitor TV 8 is an XY stage for moving the recording medium 140, and 9 is a host computer for controlling the image processing apparatus 6 and the XY stage 8.

The operator places the recording medium 140 as the measurement object on the XY stage 8 at the correct position, operates the host computer 9 while watching the monitor TV 7, and the measurement area of the evaluation pattern formed on the recording medium 140 is the microscope 2. The XY stage 8 is moved so as to enter the field of view. When the movement is completed, the computer 9 sends a measurement start signal to the image processing unit 6, and the image processing unit 6 that receives the measurement start signal captures the video signal of the TV camera 3 as a digital image. After that, the image is moved to a predetermined measurement area and the digital image is captured in the same manner. According to the proposal in Patent Document 1, the position data related to the position of each dot and the shape data related to the shape are extracted from the image data captured in this manner, and the pattern data is extracted according to the position data and the shape data of each dot. A pattern evaluation value representing a state is calculated, and landing performance evaluation is performed using a deviation amount from the ideal position, which is a difference between an ideal dot position and an actual dot position, as position data.
JP-A-4-338777

  However, in the ink jet printer as described above, it is not possible to correct a feed error caused by pitching, yawing, straightness, etc. possessed by the carriage and the recording medium moving means. Therefore, when an evaluation pattern is formed on a recording medium with such an ink jet printer, and the landing position deviation of the ink dots formed on the recording medium is measured with the above landing position measuring apparatus, the measured value includes the ink jet printer. Therefore, it is impossible to extract only the deviation amount due to the recording head.

  Further, since the landing position deviation of the ink dots is measured by a landing position measuring device that is a device different from the ink jet printer that has printed the evaluation pattern, it is not possible to eliminate the amount of deviation caused by how the recording medium is placed.

  The present invention has been made in view of such a problem, and the intended processing is only the amount of deviation caused by the recording head excluding the feeding error caused by the carriage or the moving means of the recording medium. To provide a landing position measuring method and apparatus capable of extracting and measuring landing position deviation by the same apparatus as the apparatus on which the evaluation pattern is printed, and eliminating the deviation amount caused by how to place the recording medium It is in.

  The present invention has achieved the above object by the following technical configuration.

  (1) A recording head provided with a plurality of nozzle groups for ejecting ink, a carriage on which the recording head is mounted, a first moving step for moving the carriage in the main scanning direction, and a main scanning of the recording medium A second moving step that moves in the sub-scanning direction intersecting the direction, a position detecting step that detects the position of the recording head, and the carriage that moves in the main scanning direction and that is detected by the position detecting step. A step of recording an image on the recording medium based on a position of the recording head in the main scanning direction, and an imaging for capturing an image on the recording medium instead of the recording head at a mounting position of the recording head in the carriage And a step of detecting landing positions of ink dots ejected from the plurality of nozzles from a captured image obtained by the imaging means. Landing position measuring method characterized.

  (2) A recording head provided with a plurality of nozzle groups for ejecting ink, a carriage on which the recording head is mounted, a first moving means for moving the carriage in the main scanning direction, and a main scanning of the recording medium A second moving means that moves in a sub-scanning direction that intersects the direction, a position detecting means that detects the position of the recording head, and the carriage that moves in the main scanning direction and that is detected by the position detecting means. An image recording unit that records an image on the recording medium based on a position of the recording head in the main scanning direction, an imaging unit that captures an image on the recording medium, and a plurality of the captured images obtained by the imaging unit. A landing position detecting means for detecting a landing position of the ink dots ejected from the nozzles, and a replacement of the recording head at the mounting position of the recording head in the carriage; Landing position measuring device, characterized in that said image pickup means provided with a replacement unit to be installed in Ri.

  (3) The exchanging means is a third moving means for exchanging the positions of the recording head and the imaging means by sliding the recording head and the imaging means in the main scanning direction in the carriage. The landing position measuring device according to (2), which is characterized in that

  (4) The landing position measuring apparatus according to (2) or (3), further including fourth moving means for finely moving the imaging means in the sub-scanning direction.

  According to the present invention, the image pickup means for picking up the landing position of the ink dot formed on the recording medium is provided in the vicinity of the position where the recording head nozzle is arranged, thereby causing the carriage or the recording medium moving means. It is possible to extract only the amount of deviation caused by the recording head from which the feeding error has been eliminated, and by measuring the landing position deviation with the same device that printed the evaluation pattern, the amount of deviation caused by how to place the recording medium is eliminated. It is possible to provide a landing position measurement method and apparatus that can be used.

  Embodiments of the present invention will be described below with reference to the drawings.

  Embodiments of the present invention will be described with reference to the drawings.

1. Configuration of Landing Position Measuring Device In the embodiment of the present invention, the landing position is measured by the following procedure.

  (1) An evaluation pattern is recorded on a recording medium by the landing position measuring apparatus.

  (2) With the same apparatus, the landing position deviation is measured with the recording medium as it is.

  First, the overall configuration of the landing position measuring apparatus will be described.

  FIG. 8 is an overall configuration diagram of the landing position measuring apparatus according to the embodiment of the present invention.

  The landing position measuring apparatus of the present embodiment shown in FIG. 8 has a configuration similar to that of the conventional ink jet printer described in FIG. 10, but in order to improve feed reproducibility in the main scanning direction and the sub scanning direction. In addition, a high-precision linear motor is employed as the moving means for the carriage 1102 and the recording medium 140, and the recording medium 140 is fixedly moved on the stage 1003 having a high surface accuracy.

  That is, the carriage 102 is conventionally moved in the main scanning direction by the motor 103 and the driving belt 109, but in this embodiment, the CR linear motor 1001 is used as the moving means for the carriage 1102, and the moving means for the recording medium 140 is also used. A stage 1003 and an LF linear motor 1002 are employed instead of the feed motor 107 and the feed rollers 106 and 110.

  The LF linear motor 1002 is firmly fixed to the surface plate 1008 so that the stage surface on which the recording medium 140 is placed is always parallel to the surface plate surface even when the stage 1003 moves. On the other hand, the CR linear motor 1001 is fixed on the surface plate 1008 via the bases 1004 and 1005 with high accuracy and high rigidity, and adjusted so that the carriage 1102 moves parallel to the surface surface, that is, the stage surface. Has been.

  The CR linear motor 1001 and the LF linear motor 1002 incorporate linear encoders 1130 and 1131 and origin sensors 1006 and 1007, which are used as servo control inputs during movement of the respective linear motors. 1130 is also used to generate ink ejection timing as in the prior art. The resolution of the linear encoders 1130 and 1131 is 0.5 μm, which is several tens of times higher than the resolution of a conventional inkjet printer (for example, the resolution is 21.2 μm at 1200 dpi).

  FIG. 9 shows an enlarged view of the carriage 1102 as viewed from directly above the apparatus, and FIG. 9A shows the position of the moving stage 38 when the image recording operation is performed with this apparatus. FIG. 9B shows the position of the moving stage 38 when the landing position measuring operation is performed by this apparatus. That is, the moving stage 38 is attached to the guide rail 44 in the carriage 1102 so that it can move along the guide rail 44. When performing an image recording operation with this apparatus, adjustment is performed so that the center position of the nozzle row of the recording head 120 is arranged at the reference position A in the drawing. Further, when the landing position measuring operation is performed by this apparatus, the CCD camera 42 is fixed so as to be arranged at the reference position A.

2. Image Recording Operation Next, an image recording operation of the landing position measuring apparatus according to the present embodiment will be described with reference to FIG.

  FIG. 1 is an overall block diagram of a landing position measuring apparatus according to this embodiment. The mechanism unit 16 conveys a CR linear motor 1001 for moving the carriage 1102 on which the recording heads 120, 121, 122, and 123 are mounted in the main scanning direction, and a stage 1003 on which a recording medium 140 such as a film or a glass substrate is mounted. An LF linear motor 1002 and a recovery unit 1009 for recovering ink clogging of the recording head are included.

  The moving stage 38 in the carriage 1102 is set to a position for performing an image recording operation as shown in FIG.

  The main control unit 14 is a central part that controls the entire landing position measuring apparatus including the recording head and the mechanism unit 16 and the like. The main control unit 14 is a ROM that stores a CPU, an operation program, etc., and writes various data. It is composed of a working RAM for performing reading and the like.

  The main control unit 14 outputs a control signal to the mechanism unit 16 to perform mechanism control such as movement of the carriage 1102 and movement of the recording medium 140, and further, the head drive unit 12, the memory control unit 20, and further recording. Signals are also exchanged closely with the position signal generator 11 to control the drive of the recording heads 120, 121, 122, 123.

  The I / F unit 17 receives a command and image data from the host computer, and further receives correction data, which will be described later, at an interface portion between a host computer (not shown) and the landing position measuring device.

  The memory control unit 20 transfers the command input from the I / F unit 17 to the main control unit 14 and sends an address and a write timing signal so as to write image data into the buffer memory 15 under the control of the main control unit 14. Generate.

  The main control unit 14 decodes the command input from the I / F unit 17 and sets image recording conditions such as an image recording speed and an image recording resolution based on the result, and the mechanism unit 16 and the recording unit according to the image recording conditions. The position signal generator 11 is controlled to record an image under desired conditions.

  On the other hand, image data received from a host computer (not shown) is stored in the buffer memory 15 which is a temporary memory, and then transferred to the head drive unit 12 under the control of the memory control unit 20 which receives a command from the main control unit 14. Is done.

  The head driving unit 12 records each image by driving each nozzle of the recording head according to the image data transferred from the buffer memory 15 in synchronization with the image recording position signal output from the recording position signal generating unit 11.

  Here, the buffer memory 15 has a storage capacity capable of storing image data of one band or more required for the recording heads 120, 121, 122, 123 to scan once in the main scanning direction and record an image. It is comprised from the memory provided with.

  For example, if the number of nozzles in the sub-scanning direction of each recording head is 128 nozzles and the maximum number of dots that can be recorded in one scan in the main scanning direction is 8k dots, the memory of the buffer memory 15 has 128 (nozzles). X8k (dots) x4 (colors) = 4 Mbits or more of storage capacity.

  When the image data to be transferred is enormous and the drawing speed is required to be increased, the I / F unit 17 uses, for example, a high-speed interface such as IEEE1394 in addition to the Centronics interface and the SCSI interface. May be.

3. Control of Image Recording Position Next, a method for controlling the image recording position in the landing position measuring apparatus of this embodiment will be described.

  2A and 2B are diagrams showing output signals of the linear encoder 1130. FIG. Two signals A and B having a phase shift of 90 ° are signals generated by the linear encoder 1130. FIG. 2A shows signals A and B generated when the carriage 1102 operates in the forward direction, and FIG. ) Indicate signals A and B generated when the carriage 1102 operates in the backward direction.

  As shown in FIG. 2A, when the phase of the signal A is advanced by 90 ° from the phase of the signal B, the carriage 1102 is moving in the forward direction, so that it corresponds to the rising and falling edges of each signal. Count up. Further, as shown in FIG. 2B, when the phase is delayed by 90 °, the carriage 1102 is moved in the backward direction, so that it counts down. In this way, the movement position of the carriage 1102 can be detected by counting the output signal of the linear encoder 1130.

  1 receives the two signals A and B from the linear encoder 1130 described above and the origin signal Z output from the origin sensor 1006, and actually detects the absolute position of the carriage 1102 in the main scanning direction. Is detected.

  FIG. 3 shows an example of a circuit of the recording head position detection unit 10. The signals A and B from the linear encoder 1130, the origin signal Z from the origin sensor 1006, and a clock for synchronizing the logic timing ( Based on (CLK), a count signal (PLS) and an up / down signal, that is, a moving direction signal (DIR) are generated.

  The circuit composed of 201 to 204 in FIG. 3 is a part for detecting the rising and falling timings of A. From the output of 203, a pulse synchronized with the rising timing of A is a pulse synchronized with the falling timing. 204.

  Similarly, the circuit composed of 205 to 208 in FIG. 3 is a part for detecting the rising and falling timings of B, and a pulse synchronized with the rising timing of B changes from the output of 205 to the falling timing. A synchronized pulse is output from 208.

  FIG. 4 is a timing chart thereof.

  In FIG. 4, since the phase of A at the beginning is 90 ° ahead of the phase of B, the movement direction signal DIR is the forward direction (LO level), and the phase is delayed by 90 ° from the middle of FIG. It can be seen that the signal DIR is in the backward direction (HIGH level).

  Further, the count signal PLS indicates that a pulse is output at the rising and falling timings of the two signals A and B, and it moves 0.5 μm every time one pulse is generated.

  The origin signal Z, the count signal PLS, and the movement direction signal DIR are connected to the reset (CLR), clock (CK), and up / down (UP / DW) input signals of the up / down counter 210 shown in FIG. .

  Therefore, when the carriage 102 moves to the origin position by the initialization command of the main control unit 14, the origin signal Z becomes active, the count output is cleared (count value = 0), and the count value = 0 is set as the origin thereafter. The absolute position of the carriage 1102 in the main scanning direction is output to the recording position signal generation unit 11 as a count value.

  FIG. 5 is a block diagram of the recording position signal generator 11. The count output generated by the recording head position detection unit 10 in FIG. 3 is connected to the address input of the RAM 300 via the selector 301.

  In the RAM 300, the address bus is connected to the address input AB of the RAM 300 via the other input of the selector 301, and the data bus and the access signal are stored so that the CPU in the main control unit 14 can directly read / write. Each is connected to the data bus DB and R / W of the RAM 300.

  When data is written from the main control unit 14 to the RAM 300, the selector 301 is set to the CPU side, and during the image recording operation, the selector 301 is switched so that the count value becomes the address input of the RAM 300. RAM data at an address corresponding to is output to the head drive unit 12.

  Here, if the recording position data is written in advance in the RAM 300 from the CPU of the main control unit 14, a recording position pulse is output to the head driving unit 12 every time the carriage moves and reaches the recording position. When this recording position pulse is received, the recording head is driven to eject ink onto the recording medium 140.

  FIG. 6 is a diagram illustrating the timing of the recording position pulse.

  In FIG. 6, addresses (RAM) and data (RAM) represent the addresses and data of the RAM 300, and indicate how round-trip 2-bit data written in the RAM 300 is written.

  Further, the recording position pulse in FIG. 6 is a pulse signal that gives recording timing to the head drive unit 12 and when the carriage moves, corresponding bits are selected in the forward direction and the backward direction as shown in FIG. Can be obtained.

  By the way, in FIG. 6, the output timings of pulses in the forward direction and the backward direction do not match. This is because even if the recording head is driven at the same timing in the forward direction and the backward direction, it takes a predetermined time for the ink droplets ejected from the recording head to reach the recording medium. This is because the landing position of the droplet is shifted. Therefore, the timing of the recording position pulse is set in advance so as to be different in the forward direction and the backward direction.

  Note that FIG. 6 illustrates the timing of the recording position pulse by taking an example of bidirectional image recording in which images are recorded in the forward direction and the backward direction. For example, in the case of unidirectional image recording in which image recording is performed only in the forward direction. In this case, all the bits on the return path may be set to 0. In this case, the recording position pulse is not output when the carriage is moving in the backward direction.

  In FIG. 6, for convenience, the data in the RAM 300 and the recording position pulse are described only for one set of reciprocation. However, when there are four recording heads 120, 121, 122, 123 as in this embodiment, The number of data bits in the RAM 300 may be increased to generate four sets.

4). Method for Creating Recording Position Data The method for generating the image recording timing to be output to the head drive unit 12 has been described above. Next, a method for creating recording position data to be written in the RAM 300 will be described.

  First, a method of creating image recording position data when simply recording an image at a specified resolution will be described.

Assuming that the image recording start position is Ls, the resolution pitch is Pr, and the resolution of the linear encoder is Er, the address of the RAM corresponding to the image recording position of the nth, that is, the nth column from the image recording start position is An. Is
An = (Ls + n × Pr) / Er
After all the contents of the RAM 300 are cleared to 0, An is obtained for n for all the image recording positions according to the above formula, and image recording is indicated in a desired bit of data corresponding to the address An of the RAM 300. If 1 is written, a recording position pulse can be generated with a desired image recording resolution.

5). Next, a method for measuring the amount of landing position deviation caused by the recording head while eliminating the feeding error caused by the carriage and the recording medium moving means, which is a feature of the present invention, will be described.

5-1. Elimination of displacement due to moving means As shown in the block diagram of FIG. 8, the landing position measuring apparatus of this embodiment can move the carriage and the recording medium with high accuracy by a high-precision linear motor. However, even in such a high-accuracy linear motor, due to feed errors such as pitching, yawing, and straightness, a deviation occurs as the linear motor moves as shown in FIG. FIG. 7A shows a deviation amount in the main scanning direction and the sub-scanning direction when the CR linear motor 1001 moves in the main scanning direction, and FIG. 7B similarly relates to the LF linear motor 1002. Is.

  Therefore, in the present application, a recording head is mounted on the moving stage 38 in the carriage 1102, and the objective lens 41 and the CCD camera 42 are also arranged, and the carriage 1102 is moved in the same manner as in the image recording operation to move the carriage during the image recording operation. Measurement is performed at substantially the same position as 1102.

  The reason why the recording head and the CCD camera 42 are mounted on the moving stage 38 in the carriage 1102 so that the moving stage 38 can be moved will be described.

  FIG. 15 shows the positional relationship between the recording head and the CCD camera 42 and the deviation amount in the main scanning direction and the sub-scanning direction when the CR linear motor 1001 shown in FIG. 7A moves in the main scanning direction. It is. As shown in FIG. 15, the distance between the recording head and the CCD camera 42 is about 150 mm, and the distance between the X1 position and the X2 position shown in the figure is equal to the distance between the recording head and the CCD camera 42. Yes. When the carriage 1102 moves and the position of the recording head reaches the X1 position, the position of the CCD camera 42 becomes the X2 position. When image recording is performed at this position (the position of the recording head is the X1 position), in order to measure the ink dots that have landed on the recording medium 140, the CCD camera 42 must be moved to the X1 position. At this time, if the carriage 1102 is moved and the CCD camera 42 is set to the X1 position, measurement is performed at a position different from the position where the image was recorded (the position of the recording head is the X1 position). Then, if the shift amount in the main scanning direction and the sub-scanning direction when the position of the CCD camera 42 is the X2 position is different from the shift amount in the main scanning direction and the sub-scanning direction at the X1 position, the shift amount is different. However, this method cannot eliminate the amount of deviation caused by the movement of the carriage 1102.

  On the other hand, in the present application, when the carriage 1102 moves and the position of the recording head reaches the X1 position, the measurement is performed at substantially the same position as the position of the carriage 1102 during the image recording operation. The stage 38 is moved so that the CCD camera 42 is aligned with the X1 position.

5-2. Measurement Operation Next, the landing position deviation measurement operation will be described.

  After drawing an evaluation pattern on the recording medium 140 as shown in the configuration diagram of FIG. 8, the ink dots landed on the recording medium 140 are measured with the recording medium 140 placed on the stage 1003. At this time, the moving stage 38 in the carriage 1102 during the above-described image recording operation is fixed at a position where the recording head comes to the reference position A as shown in FIG. When the measurement is performed, the CCD camera 42 is fixed at a reference position A as shown in FIG. That is, by sliding the position of the moving stage 38, the position of the recording head during the image recording operation and the position of the CCD camera 42 during the landing position deviation measurement are exchanged.

  After that, since the absolute position of the carriage 1102 can be detected by the above-described image recording position control method, the carriage 1102 moves directly to the image recording position and stops without moving to the start position (the position of the origin sensor 1006). Let Then, at that position, the image control unit 40 images the ink dots landed on the recording medium 140 by the CCD camera 42 through the objective lens 41, converts them into image data, and stores the image data in the image memory 43. Thus, by measuring at approximately the same position as the position of the carriage 1102 when image recording is performed, the image recording operation and the landing position deviation measuring operation are performed at positions where the deviation amount is equal. Measurement is possible without being affected by the amount.

  Next, the carriage 1102 is moved again in the main scanning direction and stopped when it reaches the next image recording position, and the ink dots that have landed on the recording medium 140 are imaged in the same manner as before, and after conversion to image data, Image data is stored in the image memory 43.

  The above process is repeated until the image data of the desired ink dot is stored.

  In the present embodiment, the image data at each image recording position is stored in the image memory 43. However, each time the ink dots landed on the recording medium 140 are imaged and converted into image data, the image data is read from the image data. The ink dot positions may be extracted and the ink dot positions may be recorded in the image memory 43. A method for extracting the position of the ink dot from this image data is described in 5-4. This will be described in detail in the extraction of the landing position deviation amount.

5-3. Measurement Error at Minute Movement FIG. 13 shows a single imaging range using the objective lens 41 having a magnification of about 50 times. At this time, the imaging area 45 is a 0.1 mm mouth. Then, when the nozzles of the recording head are arranged at an arrangement pitch of 1200 dpi, the nozzle interval L is 21.2 μm. Therefore, in one imaging area 45, the central nozzle n and two upper and lower nozzles (nozzle n −2 to nozzle n + 2), the ink dots landed on the recording medium 140 can be simultaneously imaged. Here, for simplicity of explanation, the recording head in which a plurality of nozzles are arranged in a row is used to perform alignment so that the nozzle n comes to the center point O of the imaging area 45. Even in the case of a recording head having a plurality of nozzle rows or a plurality of nozzle rows of a plurality of recording heads, the nozzle row to be imaged may be aligned with the center point O of the imaging area 45.

  As described above, the imaging area 45 that is a single imaging range is an area as small as a 0.1 mm mouth. Therefore, in order to capture ink dots outside the imaging area 45, it is necessary to move in the sub-scanning direction. In this case, since the carriage 1102 cannot be moved in the sub scanning direction, the carriage 1102 is moved in the sub scanning direction by the LF linear motor 1002 that is a moving unit of the recording medium 140. At this time, a deviation amount in the main scanning direction and the sub-scanning direction when the LF linear motor 1002 shown in FIG. 7B moves in the sub-scanning direction occurs. However, at present, even if the 0.5 inch recording head is the mainstream 1 inch recording head, the amount of movement is about ± 10 mm at most in the sub-scanning direction, and the carriage 1102 does not move. When the change in the shift amount accompanying the movement in the sub-scanning direction is viewed between about 150 mm from the Xa position to the Xb position shown in FIG. 7B, the main scanning direction and the sub-scanning at the Xa position in the drawing are shown. The shift amount in the main scanning direction and the sub-scanning direction at a position about 10 mm away from the Xa position can be almost ignored, so that the shift amount due to the movement of the recording medium 140 is small.

  Therefore, in order to image the ink dots outside the imaging area 45, it is possible to image in the vicinity of the image recording position by moving the recording medium 140 in the sub-scanning direction.

5-4. Extraction of landing position deviation amount Next, a landing position deviation amount extraction method in the landing position measurement apparatus of the present embodiment will be described.

  In the present application, the position of the ink dot is extracted from the image data captured at each image recording position, the position of each ink dot is represented by coordinates, and the landing position deviation is measured by the amount of displacement.

  More specifically, FIG. 16 is a diagram in which ink dots landed on the recording medium 140 when ejected from one nozzle of the recording head are imaged at four image recording positions, converted into image data, and arranged. It is. As shown in FIG. 16, the image of each point represents the position of the ink dot by coordinates (X, Y), where X is the horizontal axis and Y is the vertical axis. Here, if the center point O in the figure is a coordinate (0, 0), the position of the ink dot is the coordinate (1, 1) in the first point image that is the first image recording position, and the second point In the image of the second point that is the image recording position, the position of the ink dot is the coordinates (1, 2). Subsequently, in the third point image that is the third image recording position, the ink dot position is the coordinates (2, 2), and in the fourth point image that is the fourth image recording position, the ink dot position. Is the coordinates (2, 2).

  Looking at the positions of these four ink dots, first, coordinates (1, 1) → coordinates (1, 2), and +1 in the vertical axis direction. Next, coordinates (1, 2) → coordinates (2, 2), and +1 in the horizontal axis direction. Finally, coordinates (2, 2) → coordinates (2, 2), where it can be seen that there is no change and displacement. In addition, when the coordinates (1, 1) of the first point are used as the reference value, the coordinates (1, 2) of the second point are shifted by X = 0 and Y = 1 with respect to the reference value. The coordinates (2, 2) of the third and fourth points are X = 1 and Y = 1.

  In this way, it is possible to extract the position of the ink dot from the image data of each point, express the position of each ink dot with coordinates, and measure the amount of displacement. Furthermore, when the coordinates of a certain point are used as a reference value, it is possible to extract a landing position deviation from the reference value.

6). Example of Embodiment Next, an example of this embodiment will be described.

  FIG. 11 shows an image of ink dots landed on the recording medium 140 when ejected continuously from a nozzle of a recording head at a predetermined interval, converted into image data, and arranged in order for one line. It is. The image data shown in FIG. 11 was imaged at the same position as the position of the carriage 1102 when the image recording as a feature of the present application was performed, without being affected by the amount of deviation accompanying the movement of the carriage 1102. In addition, the ink dots landed on the recording medium 140 in a state where the recording medium 140 is placed on the stage 1003 are imaged.

  Therefore, when looking at the position of the ink dot as shown in FIG. 11, the coordinates to the point near the center do not change, but when viewed from the point near the center in the main scanning direction, the coordinates are It can be seen that the vertical axis gradually moves downward.

  This recording medium 140 is brought to a landing position measuring apparatus as shown in FIG. 17 of the prior art, and the landed ink dots are imaged, converted into image data, and arranged in order for one line in FIG. It is. Each image data shown in FIG. 12 is obtained by imaging ink dots in a form including a shift amount due to a carriage or recording medium feed error as shown in FIG. 7, and further uses a least square method. The center line M is calculated so that the error of the ink dot position is minimized. The method using the least square method is based on the displacement of the recording medium when printing the evaluation pattern by the ink jet printer as shown in FIG. 10 or the landing position measuring device as shown in FIG. It is used for correcting misalignment of the recording medium when measuring. Even when the image data shown in FIG. 12 is compared with the image data shown in FIG. 11, it can be seen that the change in the ink dot position is larger in FIG.

  In addition, as shown in FIG. 11, the coordinates to the point near the center are not actually changed, but in FIG. 12, it is measured that the coordinates to the point near the center are gradually moving upward in the vertical axis. Resulting in. Therefore, the present embodiment is also effective in eliminating the amount of deviation due to such a recording medium placement.

  Next, a second embodiment will be described.

  In the first embodiment, as shown in FIG. 13, each imaging area 45 is landed on the recording medium 140 of the central nozzle n and upper and lower nozzles (nozzle n−2 to nozzle n + 2). Only ink dots can be imaged. Therefore, in order to image the ink dots landed on the recording medium 140 when ejected from, for example, the nozzle n + 10 outside the imaging area 45, the moving stage 38 in the carriage 1102 or the CCD camera 42 in the moving stage 38 is used. Since there is no mechanism for moving the portion to which the image is attached in the sub-scanning direction, there is only a method for imaging the ink dots by moving the recording medium 140 in the sub-scanning direction by the LF linear motor 1002.

  However, when the LF linear motor 1002 shown in FIG. 7B is moved in the sub-scanning direction, a shift amount in the main scanning direction and the sub-scanning direction is generated, but the movement amount is very small, and the carriage 1102 does not move, and it is considered that the amount of displacement associated with the movement of the recording medium 140 is small.

  However, this method cannot completely eliminate the feeding error caused by the moving means of the recording medium, so that it becomes impossible to extract only the deviation amount caused by the recording head.

  On the other hand, in the second embodiment, a mechanism for moving in the sub-scanning direction a portion to which the CCD camera 42 in the moving stage 38 in the carriage 1102 is attached is provided. Actually, as shown in FIG. 14, the CCD camera mounting portion in the carriage 1102 moving stage 38 is mounted on the guide rail 46 so that the CCD camera mounting portion can move along the guide rail 46 in the sub-scanning direction. It has become. It is assumed that the guide rail 46 is aligned with a direction substantially orthogonal to the guide rail 44 for moving in the main scanning direction.

  The movement width in the sub-scanning direction of the CCD camera mounting portion may be as long as an imaging area corresponding to one band width recorded with the recording heads 120 to 123 can be secured.

  In this way, by providing a mechanism for moving in the sub-scanning direction the portion where the CCD camera 42 is attached in the carriage 1102 moving stage 38, the ink landed on the recording medium 140 is ejected from any nozzle. It becomes possible to pick up an image of dots, and it is possible to extract only the deviation amount caused by the print head from which the feeding error caused by the carriage or the moving means of the print medium is eliminated.

  In the present application, the recording head and the CCD camera 42 are mounted on the moving stage 38 in the carriage 1102 so that the moving stage 38 can be moved for printing the evaluation pattern and measuring the landing position deviation. Instead of using the moving stage 38, the recording head may be removed and replaced with the CCD camera 42 instead.

Block diagram of the landing position measuring device of this embodiment The figure which shows the output signal in the outward direction of the linear encoder of this embodiment, and a return direction 1 is a diagram illustrating an example of a circuit of a position detection unit of a recording head according to an embodiment. The figure which shows an example of the timing chart of the position detection part of this embodiment. Block diagram of the position generator of this embodiment The figure explaining operation | movement of the position generation part of this embodiment. Graph showing landing position deviation at the time of movement of CR linear motor of this embodiment Schematic of the landing position measurement device of the present embodiment The enlarged view of the carriage part of the landing position measuring apparatus of this embodiment Schematic diagram of a conventional inkjet printer The figure which shows an example of the imaging example in the landing position measuring apparatus of this embodiment The figure which shows an example of the imaging example in the landing position measuring apparatus of a prior art The figure explaining the imaging area of this embodiment The enlarged view of the carriage part of the landing position measuring apparatus of 2nd embodiment The figure explaining the relationship between the carriage position of this embodiment, and deviation | shift amount Example of imaging at four locations in the landing position measuring apparatus of this embodiment Schematic diagram of a conventional landing position measurement device

Explanation of symbols

2 Microscope 3 CCD camera 4 Light source 5 Light guide 6 Image processor 7 Monitor TV
8 XY stage 9 Host computer 10 Recording head position detection unit 11 Recording position signal generation unit 12 Head control unit 120 to 123 Recording head 14 Main control unit 15 Buffer memory 16 Mechanism unit 17 I / F unit 19 Temperature sensor 20 Memory control unit 38 Moving stage 40 Image control unit 41 Objective lens 42 CCD camera 43 Image memory 44, 46 Guide rail 45 Imaging area 100, 101 Roller 102 Carriage 103, 107 Motor 106 Platen 108 Origin sensor 110 Feed roller 111 Medium detection sensor 130 Linear encoder 140 Recording Medium 201, 202, 204, 206 Latch 203, 204, 207, 208 Gate 210 Up / down counter 300 RAM
301 selector 1001 CR linear motor 1002 LF linear motor 1003 stage 1004, 1005 base 1006, 1007 origin sensor 1008 surface plate 1009 recovery unit 1130, 1131 linear encoder

Claims (4)

A recording head provided with a plurality of nozzle groups for discharging ink;
A carriage on which the recording head is mounted;
A first moving step of moving the carriage in the main scanning direction;
A second moving step of moving the recording medium in the sub-scanning direction intersecting the main scanning direction;
A position detecting step for detecting the position of the recording head;
Moving the carriage in the main scanning direction and recording an image on the recording medium based on the position of the recording head in the main scanning direction detected by the position detecting step;
Replacing with an imaging means for imaging an image on the recording medium instead of the recording head at the mounting position of the recording head in the carriage;
And a step of detecting landing positions of ink dots ejected from the plurality of nozzles from a captured image obtained by the imaging means. A recording head provided with a plurality of nozzle groups for discharging ink;
A carriage on which the recording head is mounted;
First moving means for moving the carriage in the main scanning direction;
Second moving means for moving the recording medium in the sub-scanning direction intersecting the main scanning direction;
Position detecting means for detecting the position of the recording head;
Image recording means for moving the carriage in the main scanning direction and recording an image on the recording medium based on the position of the recording head in the main scanning direction detected by the position detecting means;
Imaging means for capturing an image on the recording medium;
Landing position detection means for detecting landing positions of ink dots ejected from the plurality of nozzles from a captured image obtained by the imaging means;
An impact position measuring apparatus, wherein an exchange means capable of mounting the imaging means instead of the recording head is provided at the mounting position of the recording head in the carriage.   The exchanging means is a third moving means for exchanging positions of the recording head and the imaging means by sliding the recording head and the imaging means in the main scanning direction in the carriage. The landing position measuring device according to claim 2.   4. The landing position measuring apparatus according to claim 2, further comprising a fourth moving unit that minutely moves the imaging unit in the sub-scanning direction.

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