JP2007276264A - Inkjet recording device, and its controlling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording device which can form an image of a high picture quality and a high printing precision, and to provide its controlling method. <P>SOLUTION: This inkjet recording device includes a distal end distance detecting sensor, a rear end distance detecting sensor, a tilting angle detecting means, and a discharging timing correcting means. In this case, the distal end distance detecting sensor is provided on the distal end of a printing head, and detects a distal end distance which is a distance to a recording medium. The rear end distance detecting sensor is provided on the rear end of the printing head, and detects a rear end distance which is a distance to the recording medium. The tilting angle detecting means detects a tilting angle to the carrying direction of the nozzle surface of the recording head based on the detected distal end distance and the detected rear end distance. The discharging timing correcting means corrects a timing by which an ink is discharged from a nozzle based on the detected tilting angle and the moving speed of a carriage in a discharging section. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to an ejection timing generation method for an inkjet recording apparatus such as an inkjet printer. More specifically, the present invention relates to a configuration for acquiring ink discharge timing by acquiring positional information of a carriage on which a print head is mounted based on a detection signal from a recording position detection mechanism using an encoder or the like.

  An ink jet recording apparatus known as an ink jet printer has various advantages and has a wide range of applications. In order to cope with such a wide range of applications, it is required to reduce the size of the apparatus, increase the printing speed, and increase the definition of recorded images.

  In the conventional inkjet recording apparatus, in order to improve the accuracy of the image, the carriage scanning speed during printing on the recording medium (that is, during ink ejection from the print head) is controlled so as to be constant at the target speed. Yes.

  FIG. 10 is a diagram for explaining the principle of detecting the scanning position of the carriage using an encoder and generating the ejection timing based on the signal.

  In FIG. 10, the time indicated by ↓ is the time when the encoder signal is input to the ejection control unit, and the time indicated by ● is the ejection timing of the print head.

  Here, it is assumed that the encoder forms a slit with a resolution of 300 lpi (1/300 inch pitch), for example, and that the printing resolution is 2400 dpi (1/2400 inch pitch). In this case, ejection driving is performed 8 times at 2400/300 during each cycle of the input signal of the encoder signal. ΔT is the time from the input timing of the encoder signal to the first discharge in that section.

  In the conventional control, control is performed so that the scanning speed of the carriage ejecting ink from the print head is equal to the target speed, so the encoder signal period is sufficiently short with respect to the change in the scanning speed of the carriage. . Therefore, the difference in speed between adjacent sections of the encoder signal cycle is treated as small as not causing a problem, and the scanning speed of the current section, which is the target section for controlling the discharge timing, is equal to the speed data obtained in the adjacent previous section. The method is taken.

  In order for the carriage to start printing on the recording medium at the target speed, the carriage must be accelerated to reach the target speed before reaching the print area of the recording medium. Therefore, the apparatus size is increased by a length corresponding to the run-up distance required for the print head to accelerate and the run-up distance required for the print head to decelerate.

  Further, if the carriage scanning speed is increased in order to increase the printing speed, the run distance of the print head is further increased.

  Therefore, in order to reduce the size of the device and increase the printing speed, it is necessary to have a technique to perform recording by ejecting ink while the carriage is accelerated to the target speed and decelerated from the target speed on the recording medium. It becomes.

  FIG. 11 is a diagram showing the speed fluctuation in the scanning of the recording head in the conventional example.

  In FIG. 11, the vertical axis indicates the scanning speed, the horizontal axis indicates the elapsed time from the start of scanning, the encoder cycle time in the previous section is T1, and the encoder cycle time in the current section is T2. In the acceleration / deceleration region shown in FIG. 11, since the change in scanning speed is large, if ejection is performed by the conventional ejection timing control described in FIG. 10, T1 = T2 shown in FIG. 11 is controlled. However, in the acceleration / deceleration region, there is a difference between the encoder cycle time T1 and the encoder cycle time T2. Therefore, if the control is performed with T1 = T2, it does not land at the assumed location, and therefore the image accuracy is adversely affected. give.

  FIG. 12 is a diagram illustrating a force component applied to an ink droplet ejected from a print head in a conventional example.

  In FIG. 12, the distance between the ink ejection surface of the print head and the recording medium (sometimes referred to as the distance between papers or between papers) is D, the ink ejection speed of the print head is Vj, and the carriage speed is Vn.

  As shown in FIG. 12, the ejected ink droplets land on the recording medium at a combined speed of the ejection speed Vj and the carriage speed Vn. Therefore, the ink droplet landing position is determined according to the combined speed of the ejection speed Vj and the carriage speed Vn and the inter-paper distance D.

  As a technique for improving the landing accuracy in the acceleration / deceleration region, a method of providing a LUT storing a speed profile and controlling the speed along this LUT is known (for example, see Patent Document 1).

  In addition, based on the position correction amount at the target speed of the carriage, a correction amount table showing the relationship between an arbitrary carriage speed and position correction amount is provided, and the correction amount table is added to the carriage speed detected by measuring the encoder cycle. To determine the position correction amount. A method of controlling ink ejection from the print head is known (see, for example, Patent Document 2).

  Further, the carriage needs to be opposed to and arranged with high accuracy with respect to the recording medium. That is, the print head is always present at an appropriate height position with respect to the recording medium, and the ink discharge port of the print head needs to be parallel to the recording medium.

  Therefore, when an inkjet recording apparatus is manufactured, the interval between the platen and the carriage is adjusted to an appropriate value. In addition, the arrangement of the attachment angles of the print heads is adjusted so that the ink discharge ports of the print head are parallel to the recording medium.

  Here, in the current adjustment process, the operator makes an adjustment while observing which side the carriage and the carriage shaft are inclined as viewed from the outside of the side surface of the ink jet recording apparatus. As another adjustment method, printing is actually performed on an object to be printed, and the inclination of the carriage is determined and adjusted by looking at the print result.

As a method of adjusting as described above, a method of adjusting an inclination angle with respect to a reference plane by rotating the carriage about the carriage axis is known (for example, see Patent Document 3).
JP 2003-276269 A JP 2004-034650 A JP 2004-306374 A

  However, the carriage is installed in a slightly inclined state with respect to the recording medium due to an error in operating the printer.

  FIG. 13 is a diagram illustrating a configuration of a conventional print head.

  The print head has a plurality of nozzles, and the nozzles are constituted by a plurality of ink ejection openings. It is the figure seen from the recording medium.

  FIG. 14 is a diagram illustrating a state in which the carriage is inclined with respect to the recording medium.

  In FIG. 14, the horizontal axis represents the direction in which the recording medium is conveyed, and the vertical axis represents the distance between the recording medium and the print head. In FIG. 14, the distance between the recording medium and the print head at point A is different from the distance between the recording medium and the print head at point C. That is, the distance between the print head and the recording medium is different between the upstream side and the downstream side in the conveyance direction of the recording medium. Supplementally, in FIG. 14, the print head moves perpendicular to the paper surface.

  When an image is formed on the recording medium in the state shown in FIG. 14, the individual ink ejection openings provided in the print head form dots on the recording medium at substantially different coordinates. That is, there is a difference in the head-paper distance between the front and rear ink discharge ports in the same nozzle row.

  FIG. 15 is a diagram illustrating a case where ejection is performed at a normal timing when the carriage is inclined with respect to the recording medium.

  Since the distance between the head and the paper is different for each ink ejection port in the nozzle, the time until the ink lands on the paper surface is different. For this reason, dots on the recording medium are displaced from each other, and the image quality and printing accuracy are lowered.

  In addition, when the carriage is tilted in the XY direction (main scanning direction), the inter-paper distance for each ink ejection port in the nozzle does not change, so the delay time is not affected by the carriage speed. For this reason, if the delay time is set for each nozzle, it can be corrected.

  On the other hand, when the carriage is tilted with respect to the recording medium, if the delay time is set and corrected for each nozzle, the distance between the papers differs for each ink ejection port in the nozzle, so that it is affected by the carriage speed. .

  For this reason, when printing is performed in an area where the carriage speed changes, such as the acceleration / deceleration area, the delay time must be corrected in consideration of the carriage speed at that time.

An object of the present invention is to provide an ink jet recording apparatus capable of forming an image with high image quality and high printing accuracy, and a control method therefor.

The present invention relates to a tip distance detection sensor provided at the tip of a print head in an ink jet recording apparatus that uses a print head that discharges ink and discharges ink from the print head onto a recording medium. A leading edge distance detection sensor that detects a leading edge distance that is a distance from the medium, and a trailing edge distance detection sensor that is provided at the trailing edge of the print head, and that detects a trailing edge distance that is a distance from the recording medium. An edge distance detection sensor, an inclination angle detection means for detecting an inclination angle of the nozzle surface of the recording head with respect to the transport direction based on the detected tip distance and the trailing edge distance; and the detected inclination angle; Ink jet having discharge timing correction means for correcting the timing of discharging ink from the nozzles based on the carriage moving speed in the discharge section A recording apparatus.

According to the present invention, the inkjet recording apparatus can produce an image with high image quality and high printing accuracy.

  The best mode for carrying out the invention is the following embodiment.

  In this specification, “print” refers not only to the formation of information such as characters and graphics, but also to the formation of images, patterns, patterns, etc. on a wide print medium, or the processing of a print medium. Refers to cases. In other words, “prints” are widely used to display images, patterns, patterns, etc. on print media, regardless of whether they are significant or not, and whether or not they are manifested so that humans can perceive them visually. When forming or when processing a print medium.

  The “recording medium” is not only paper used in a general printing apparatus, but also widely, cloth, plastic film, metal plate, glass, ceramics, wood, leather, etc. that can accept ink. .

  Further, the “ink” refers to a liquid that is applied to a print medium and used for forming an image, a pattern, a pattern, or the like, processing the print medium, or processing an ink.

  FIG. 1 is a perspective view schematically showing the internal structure of an inkjet printer 100 that is Embodiment 1 of the present invention.

  The ink jet printer 100 includes a print head 1, a carriage 2, a carriage shaft 3, an encoder film 4, a front end distance detection sensor 5 a, a rear end distance detection sensor 5 b, and an encoder sensor 6. The ink jet printer 100 includes a transport roller 7, a platen 8, a maintenance device 9, and a head cap 10.

  The print head 1 has one or a plurality of nozzles for ejecting ink and printing, is mounted on the carriage 2, is scanned, and records on the recording medium P. The carriage 2 carries the head 1 and scans in the main scanning direction. The carriage shaft 3 is a guide when the carriage 2 performs main scanning.

  The encoder film 4 is used when the print timing by the print head 1 is set. The tip distance detection sensor 5 a is disposed at the tip of the side surface of the carriage 2 and detects the tip distance that is the distance from the recording medium P. The rear end distance detection sensor 5 b is disposed at the rear end of the side surface of the carriage 2 and detects a rear end distance that is a distance from the recording medium P.

  The maintenance device 9 performs capping of the print head 1, wiping of the ink ejection surface of the print head 1, and recovery of the print head 1. The head cap 10 capping the print head 1 to seal the nozzles of the print head 1 and prevent the ink from drying.

  Next, the operation of the ink jet printer 100 will be described.

  When the printing operation is started, the recording medium P is fed to a paper feeding position by a paper feeding roller (not shown) and conveyed to a specific printing start position by a conveying roller 7. The recording medium P conveyed to the recordable area by the conveying roller 7 is supported by the platen 8 from below.

  The carriage 2 reciprocates along a main scanning direction indicated by arrows Q1 and Q2 in a scanning area including a recording area of a carriage motor (not shown). During this time, the print head 1 mounted on the carriage 2 ejects ink from the ink ejection port toward the recording medium P located below the ink ejection port, thereby recording for one scan.

  When one main scanning is completed, the recording medium P is conveyed by a fixed amount in the sub-scanning direction indicated by the arrow R to prepare for the next main scanning. Recording is performed by repeating these main scanning and sub-scanning.

  Next, the distance detection operation by the front end distance detection sensor 5a and the rear end distance detection sensor 5b in the first embodiment will be described.

  FIG. 2 is a diagram illustrating an operation of detecting the distance between each of the front end distance detection sensor 5a and the rear end distance detection sensor 5b and the recording medium P in the first embodiment.

  The tip distance detection sensor 5 a is pulse-driven by the drive circuit 20, and when the light source 21 generates the detection light f, the light projection lens 22 condenses the detection light f emitted from the light source and irradiates the target object 30. To do.

  The reflected light of the detection light f from the target object 30 is condensed on a one-dimensional position detection element 24 such as a PSD or a CCD via the light receiving lens 23. The position detection element 24 outputs a detection signal corresponding to the amount of displacement of the imaging position with respect to the reference position. The amplifying circuit 25 amplifies this detection signal, and detects the front end distance (distance between the front end distance detection sensor 5a and the recording medium P) and the rear end distance (distance between the rear end distance detection sensor 5b and the recording medium P). .

  Further, by detecting the leading end distance and the trailing end distance, the inclination angle of the carriage 2 with respect to the recording medium P can be obtained, so that the distance from the recording medium P at each ink discharge port is obtained.

  FIG. 3 is a block diagram illustrating a schematic configuration of a control system of the inkjet printer 100.

  Recording data such as characters and images to be recorded in the inkjet printer 100 and control data are transmitted from the external device 200 such as a host computer, and these data are stored in the reception buffer 41 of the inkjet printer 100. Further, data for confirming whether the data transmitted from the external device 200 is correctly transferred and data for informing the operation state of the ink jet printer 100 are transmitted from the ink jet printer 100 to the external device 200 such as a host computer. Is done.

  Data stored in the reception buffer 41 is data to be recorded when the print head 1 performs main scanning under the control of the CPU 42 that performs processing such as calculation, discrimination, and control in accordance with a program stored in the ROM 50. And stored in a recording unit in the RAM 43.

  The data recorded in the recording unit is transferred to the print head 1 by the print head control unit 51, and the print head 1 is controlled to record character and image data. Further, the print head control unit 51 detects temperature information indicating the state of the print head 1 and sends it to the CPU 42, transmits the information to the print head control unit 51, and controls the ink ejection operation of the print head 1. .

  The CPU 42 has a timing correction value calculation unit 53. The timing correction value calculation unit 53 controls the timing correction unit 60 in the print head control unit 51 to calculate the ink ejection timing correction amount of the print head 1. That is, the ink ejection timing correction amount of the print head 1 is calculated based on the control data and the data detected by the sensor 47 prior to the start of printing on the recording medium P according to the print data received from the external device 200. It is stored in the recording unit in the RAM 43.

  Further, the machine control unit 44 controls driving of the machine unit 45 such as a carriage motor or an LF motor in accordance with a command from the CPU 42.

  The sensor control unit 46 sends a signal from the sensor unit 47 configured by various sensors to the CPU 42. The sensor unit 47 includes a carriage position detection sensor such as an encoder sensor that detects the position of the carriage 2 and a sensor that measures the distance between the print head 1 and the recording medium P.

  In addition, the display panel control unit 48 performs drive control of the LED of the operation / display unit, the display unit 49 including a liquid crystal display element, and the like according to commands from the CPU 42.

  Next, an operation in which the inkjet printer 100 controls the ejection timing will be described.

  In addition, when the calculation of the data regarding discharge timing control shown below and its result are memorize | stored, it memorize | stores in the recording part etc. in CPU42 or RAM43.

  FIG. 4 is a diagram illustrating a discharge timing generation method according to the first embodiment of the present invention.

  In FIG. 4, a section Tb indicates the encoder cycle time two times before the current section with respect to the encoder cycle related to the discharge control, the section Ta is the encoder cycle time of the previous section, and the section Tn is the current section. . Also, the average scanning speed obtained from the encoder period time two times before the current section is Vb, the average scanning speed obtained from the encoder period time of the previous section is Va, and the average is obtained from the encoder period time in the current section. Let the scanning speed be Vn.

  In the first embodiment, since the encoder cycle time Tn in the current section related to the discharge control cannot be known in the current section, it is based on the encoder cycle time Tb two times before the current section and the encoder cycle time Ta of the previous section. Predict.

First, it can be considered that the change in speed changes at a constant rate in a minute time. Thus, the speed change between the encoder cycle time Tb two times before the current zone and the encoder cycle time Ta of the previous zone, the speed change of the encoder cycle time Ta of the previous zone, and the encoder cycle time Tn of the current zone. ,
(Vb−Va) / (Tb−Ta) = (Va−Vn) / (Ta−Tn)
It is. In this case, it is assumed that the change in the encoder cycle time with respect to the change in the average scanning speed of the print head 1 is very small and can be ignored. by this,
Vb-Va = Va-Vn
Which is considered to be
Vn = 2Va-Vb
The following relational expression can be obtained.

Next, the average scanning speed of each section can be obtained based on the encoder cycle time and the encoder slit interval. When the slit interval of the encoder is L, the encoder cycle time Tn in the current interval is based on the average scanning speed Vn in the current interval and the encoder slit interval L.
Vn = L / Tn
It is.

Va and Vb are also similar to the above.
Va = L / Ta, Vb = L / Tb
It is. Therefore, the encoder cycle time Tn in the current section is Tn = 1 / (2 / Ta−1 / Tb)
And the known encoder cycle time Tb two times before the current interval and the encoder cycle time Ta of the previous interval can be predicted.

  Actually, since there is a distance between the recording medium P and the ejection port of the print head 1, there is a time difference between the ejection of the ink and the landing on the recording medium P, thereby landing at the ideal position. I can't.

  In the first embodiment, the delay time ΔT until the first ejection is made variable, thereby correcting the time difference from the time when ink is ejected until the ink reaches the recording medium P.

  In FIG. 12, the front end distance and the rear end distance are D, the ink ejection speed of the recording print head 1 is Vj, the estimated average scanning speed in the current section is Vn, and the reference scanning speed is V0. To do.

  Here, the delay time ΔT can be obtained as follows.

  The time from when the ink is ejected from the print head 1 until it lands on the recording medium P is D / Vj because it is the time when the leading edge distance and trailing edge distance D are moved at the ejection speed Vj. The distance that the print head 1 moves during the time from ink ejection to landing is considered to have moved by the time of D / Vj at the speed Vn, and the distance is Vn × D / Vj. .

  Further, when V0−Vn is multiplied by the time until landing, the difference between the position where the ink lands when scanned at the speed V0 and the position where the ink lands when scanned at the speed Vn can be calculated. it can.

  Then, by dividing the difference between the landing positions by the scanning speed V0, the ink landing position when scanning at the reference scanning speed V0 and the estimated current scanning speed Vn. A delay time ΔT for correcting the difference from the ink landing position is obtained. That is, the delay time ΔT that delays the discharge timing as a whole can be obtained.

The delay time ΔT is
ΔT = D / Vj × (V0−Vn) / V0
Therefore, V0 = L / T0, from the above equation of Vn,
ΔT = (Tn−T0) × D / T0 × Vj
It is. Therefore,
ΔT = {TaTb / (2Tb−Ta) −T0} × D / T0 × Vj
Get.

  Next, the operation of the first embodiment of the present invention will be described.

  FIG. 5 is a flowchart illustrating the operation of the inkjet printer 100 according to the first embodiment.

  In the external apparatus 200, printing is instructed by application software such as word processing software or graphic software, and thereby the printing control program stored in the storage unit or the like in the RAM 43 is loaded on the memory. The CPU 42 executes the loaded print control program, whereby the flowchart shown in FIG. 5 is started.

  The external apparatus 200 displays a selection screen for selecting the type and size of the print medium, the print quality mode, and the like. Then, it waits for the operator to select such information and press the print start key (S1). When the print start key is pressed, the front end distance and rear end distance of the print head 1 are detected by the front end distance detection sensor 5a and the rear end distance detection sensor 5b of the carriage 2 (S2). In order to obtain the inclination angle of the carriage 2 with respect to the recording medium P based on the front end distance and the rear end distance, the front end distance and the rear end distance are generated for each section in which the nozzles are divided into a plurality (S3). This data (front end distance, rear end distance data) is held in the storage unit in the RAM 43.

  As a result, for each section in which the nozzles are divided into a plurality of sections, the front end distance and the rear end distance D are different from each other. And get based on.

  FIG. 6 is a diagram illustrating a schematic configuration of the timing correction unit 60 according to the first embodiment.

  The timing correction unit 60 can discharge from one nozzle at different discharge timings by having the number of divided nozzles, not the number of each nozzle but the number of divided nozzles.

  In FIG. 6, the section detector 61 monitors a signal corresponding to the position of the carriage 2 output from the encoder sensor 6 on the platen.

  The register 62 is a shift register that temporarily holds the encoder period time in one section read from the section detector 61, and the register 63 stores the encoder period time in one section output from the register 62. , A shift register that temporarily holds.

  The encoder cycle calculation circuit 65 calculates the encoder cycle time Tn of the current section based on the data stored in the register 62 and the register 63.

  The correction time calculation circuit 66 determines the ink at the current position based on the encoder period time Tn of the current section obtained by the encoder period calculation circuit 65 and the leading end distance and trailing end distance D held in the storage unit in the RAM 43. A delay time ΔT of the discharge timing is calculated.

  The print timing delay circuit 67 outputs the output timing of the drive signal for controlling the ink discharge of the print head 1 generated by the CPU 42 according to the delay time ΔT of the ink discharge timing at the current position of the carriage 2 calculated by the correction time calculation circuit 66. Delay.

  In the first embodiment, the ejection timing control is performed in the acceleration region in the scanning region of the print head 1. However, the control can be performed in the deceleration region in the same manner as the ejection timing control in the acceleration region.

  Furthermore, not only in the acceleration / deceleration region but also in the constant speed control section, even when there is a speed fluctuation, the same control as the discharge timing control in the acceleration region can be performed.

In Example 1, a plurality of additional sensors are provided between the front end distance detection sensor and the rear end distance detection sensor, and the distance between each of the additional sensors and the recording medium is output.

  FIG. 7 is a flowchart showing the operation of the inkjet printer 100 according to the second embodiment of the present invention.

  In this flowchart, printing is instructed by application software such as word processing software or graphic software in the external apparatus 200, and thereby a print control program stored in a storage unit or the like in the RAM 43 is loaded onto the memory. As a result, the CPU 42 starts executing the flowchart shown in FIG.

  The external apparatus 200 displays a selection screen for selecting the type and size of the print medium, the print quality mode, and the like. Then, it waits for the operator to select such information and press the print start key (S11). When the print start key is pressed, the front end distance detection sensor 5a and the rear end distance detection sensor 5b of the carriage 2 detect a front end distance and a rear end distance, which are distances between the print head 1 and the recording medium P (S12). . An inclination angle of the carriage 2 with respect to the recording medium P is obtained based on the front end distance and the rear end distance. And the front-end | tip distance and rear-end distance for every area which divided the nozzle into plurality are produced | generated (S13). The data of the front end distance and the rear end distance is held in the storage unit in the RAM 43.

  As a result, for each section in which the nozzles are divided into a plurality of sections, the front end distance and the rear end distance D are different from each other. Time ΔT is obtained.

  Next, when print data is received via the external device 200 (S14), the carriage 2 starts printing, and the front end distance detection sensor 5a and the rear end distance detection sensor 5b of the carriage 2 are detected at each ink discharge timing. The front end distance and rear end distance of the print head 1 are detected. The detected distance is stored in the CPU 42 and the recording unit in the RAM 43 (S15).

  Next, the timing correction value calculation unit 53 calculates the delay time ΔT of the ink ejection timing in the current section. In accordance with the calculated delay time ΔT of the ink discharge timing, the drive signal for ink discharge control is delayed to correct the ink discharge timing (S16). Continue until printing on the recording medium P by the print data is completed (S17).

  FIG. 8 is a diagram illustrating a schematic configuration of the timing correction unit 60a.

  The timing correction unit 60a can discharge from one nozzle at different discharge timings by having the number of divided nozzles, not the number of nozzles but the number of divided nozzles.

  The section detector 61 monitors a signal corresponding to the position of the carriage 2 output from the encoder sensor 6 on the platen.

  The register 62 is a shift register that temporarily holds the encoder cycle time in one section read from the section detector 61. The register 63 is a shift register that temporarily holds the encoder cycle time in one section output from the register 62.

  The register 64 detects the front end distance and the rear end distance in the print head 1 by the front end distance detection sensor 5a and the rear end distance detection sensor 5b of the carriage 2 at each ink discharge timing. The register 64 is a shift register that temporarily holds the front end distance and the rear end distance for each section obtained by dividing the nozzle into a plurality of sections.

  The encoder cycle calculation circuit 65 calculates the encoder cycle time Tn of the current section based on the data stored in the register 62 and the register 63.

  The correction time calculation circuit 66 determines the ink ejection timing at the current position based on the encoder period time Tn of the current section obtained by the encoder period calculation circuit 65 and the leading edge distance and trailing edge distance D held in the register 64. The delay time ΔT is calculated.

  The print timing delay circuit 67 outputs the output timing of the drive signal for controlling the ink discharge of the print head 1 generated by the CPU 42 according to the delay time ΔT of the ink discharge timing at the current position of the carriage 2 calculated by the correction time calculation circuit 66. Delay.

  In the second embodiment, the ejection timing control for the acceleration area in the scanning area of the print head 1 can be applied to the ejection timing control for the deceleration area.

  Furthermore, when there is a speed fluctuation in the constant speed control section as well as the acceleration / deceleration area, the discharge timing control for the acceleration area can be applied.

  In multi-pass printing, printing is performed by making multiple reciprocations of one scan, so printing in the main scanning direction Q2 (hereinafter referred to as the backward direction) is performed in the main scanning direction Q1 (hereinafter referred to as the forward direction). Print on the part that overlaps the part. When printing in the backward direction, since the recording medium P contains ink by printing in the forward direction, the leading edge distance and trailing edge distance of the print head 1 are changed from before printing. In order to detect the change between the papers, the front end distance and rear end distance of the print head 1 are detected at two points of the front end distance detection sensor 5a and the rear end distance detection sensor 5b, and the timing correction unit 60 corrects the timing. To do.

  FIG. 9 is a flowchart showing the operation of the ink jet printer 100 according to the third embodiment of the present invention.

  When the external apparatus 200 instructs printing using application software such as word processing software or graphic software, the printing control program stored in the storage unit or the like in the RAM 43 is loaded onto the memory. The CPU 42 executes the loaded print control program, whereby the flowchart shown in FIG. 9 is started.

  The external device 200 selects multi-pass printing in the print quality mode and waits for the print start key to be pressed (S21). When the print start key is pressed, the front end distance detection sensor 5a and the rear end distance detection sensor 5b of the carriage 2 detect the front end distance and rear end distance of the print head 1, and based on the difference between the front end distance and the rear end distance. Thus, the inclination angle of the carriage 2 with respect to the recording medium P is obtained (S22). Therefore, data on the front end distance and rear end distance for each section in which the nozzles are divided into a plurality of sections is generated (S23). The generated data is held in the storage unit in the RAM 43.

  As a result, for each section in which the nozzles are divided into a plurality of sections, the front end distance and the rear end distance D are different from each other. Based on, get.

  Next, when print data is received via the external device 200 (S24), the carriage 2 prints in the forward direction (S25). Thereafter, printing is started in the backward direction (S26). During backward printing, the front end distance and rear end distance of the print head 1 are detected at the two points of the front end distance detection sensor 5a and the rear end distance detection sensor 5b, and stored in the CPU 42 and the recording unit in the RAM 43 (S27). .

  Next, the timing correction value calculation unit 53 calculates the delay time ΔT of the ink ejection timing in the current section. In accordance with the calculated delay time ΔT of the ink ejection timing, the drive signal for ink ejection control is delayed, the ink ejection timing is corrected (S28), and the backward printing is finished (S29). The process is continued until printing on the recording medium P by the print data is completed (S30).

  In the third embodiment, the ejection timing control for the acceleration area in the scanning area of the print head 1 can be applied to the ejection timing control for the deceleration area.

  Further, when there is a speed fluctuation in the constant speed control section as well as the acceleration / deceleration area, the discharge timing control for the acceleration area can be applied.

  According to the above-described embodiment, a plurality of discharge periods can be determined in consideration of the acceleration in the previous section. In addition, the timing of a plurality of ejections can be entirely shifted based on the relative speed between the print head 1 and the recording medium P estimated for the current section in which the ejection is performed. Therefore, according to the above embodiment, the deviation from the landing position of the regular ejected ink droplets can be reduced.

A front end distance detection sensor 5a and a rear end distance detection sensor 5b are provided at the end portions of the print head. However, the present invention is not limited to this form, and the front end distance detection sensor 5a and the rear end distance detection are provided on the inner side of the print head in the transport direction as long as the print head inclination (tilt angle) and distance can be detected. A sensor 5b may be provided.

According to the present invention, since stable recording can be performed in a wide range including the acceleration / deceleration region, the apparatus size can be reduced even in applications requiring high quality such as photographs, art, and pools.

1 is a perspective view schematically showing an internal structure of an inkjet printer 100 that is Embodiment 1 of the present invention. FIG. FIG. 6 is a diagram illustrating an operation of detecting the distance between each of the leading end distance detecting sensor 5a and the trailing end distance detecting sensor 5b and the recording medium P in the first embodiment. 2 is a block diagram illustrating a schematic configuration of a control system of the inkjet printer 100. FIG. It is a figure explaining the discharge timing production | generation method in Example 1 of this invention. 2 is a flowchart illustrating an operation of the inkjet printer 100 according to the first embodiment. FIG. 3 is a diagram illustrating a schematic configuration of a timing correction unit 60 according to the first embodiment. It is a flowchart which shows operation | movement of the inkjet printer 100 in Example 2 of this invention. It is a figure which shows schematic structure of the timing correction part 60a. 6 is a flowchart illustrating an operation of an inkjet printer 100 that is Embodiment 3 of the present invention. It is a figure explaining the principle which detects the scanning position of a carriage using an encoder, and produces | generates a discharge timing based on the signal. It is a figure which shows the speed fluctuation | variation in the scan of the recording head in a prior art example. In the conventional example, it is a figure which shows the force component added to the ink droplet discharged from the print head. It is a figure which shows the structure in the conventional print head. FIG. 3 is a diagram illustrating a state where a carriage is inclined with respect to a recording medium. FIG. 10 is a diagram illustrating a case where ejection is performed at a normal timing when the carriage is inclined with respect to the recording medium.

Explanation of symbols

100: Inkjet printer,
1 ... Print head,
2 ... carriage,
3 Carriage shaft,
4 ... Encoder film,
5a ... tip distance detection sensor,
5b ... rear end distance detection sensor,
6 ... Encoder sensor,
10 ... Head cap,
20 ... Drive circuit,
21 ... light source,
24: Position detecting element.

Claims (10)

In an inkjet recording apparatus that uses a print head that discharges ink and discharges and records ink from the print head to a recording medium.
A tip distance detection sensor that is provided at the tip of the print head in the transport direction and detects the tip distance that is the distance between the recording medium and the print head;
A rear end distance detection sensor that is provided at a rear end portion in the transport direction of the print head and detects a rear end distance that is a distance between the recording medium and the print head;
An inclination angle detection means for detecting an inclination angle of the nozzle surface of the recording head with respect to the conveying direction based on the detected leading edge distance and trailing edge distance;
Discharge timing correction means for correcting the timing of discharging ink from the nozzles based on the detected inclination angle and the movement speed of the carriage in the discharge section;
An ink jet recording apparatus comprising: In claim 1,
The discharge timing correction means includes
An encoder that calculates the encoder cycle time Tn of the current section based on the encoder cycle time in one section corresponding to the position on the platen of the carriage output from the encoder sensor, the tip distance, and the rear end distance A period calculation circuit;
A correction time calculation circuit for calculating a delay time ΔT of the ink ejection timing based on the encoder cycle time Tn of the current section obtained by the encoder cycle calculation circuit, the tip distance, and the rear edge distance;
A print timing delay circuit for delaying the output timing of the drive signal for controlling the ink ejection of the print head according to the delay time ΔT calculated by the correction time calculation circuit;
An ink jet recording apparatus, characterized by comprising: In claim 1,
Position signal output means for outputting a signal for each relative distance between the print head and the recording medium when the print head and the recording medium move relative to each other;
An encoder sensor for detecting the scanning position of the print head and outputting a signal for each specific distance;
An ink jet recording apparatus comprising: In claim 1 or claim 3,
The inkjet recording apparatus, wherein the leading edge distance detection sensor and the trailing edge distance detection sensor are optical sensors. In any one of Claims 1-4,
A plurality of additional sensors provided between the front end distance detection sensor and the rear end distance detection sensor, each having an additional sensor that outputs a distance between each of the additional sensors and a recording medium, Inkjet recording apparatus. In any one of Claims 1-5,
The ejection timing correction means includes Tb as the cycle immediately preceding the current section, Ta as the period of the previous section, Tn as the period of the current section, D as the distance between the recording medium and the discharge port of the print head, and ink of the print head. When the discharge speed is Vj, the encoder signal time interval corresponding to the reference scanning speed is T0, and the delay time until the first discharge in the current section is ΔT,
ΔT = {TaTb / (2Tb−Ta) −T0} × D / T0 × Vj
Ink jet recording apparatus, characterized in that the delay time ΔT is obtained and corrected based on the above. In any one of Claims 1-5,
The ejection timing correction means includes Tc as the period three times before the current section, Tb as the period two times before the current section, Ta as the period before the current section, Tn as the period of the current section, When the distance from the outlet is D, the ink ejection speed of the print head is Vj, the encoder signal time interval corresponding to the reference scanning speed is T0, and the delay time until the first ejection in the current section is ΔT,
ΔT = {TaTbTc / (3TbTc−3TaTc + TaTb) −T0} × D / T0 × Vj
Ink jet recording apparatus, characterized in that the delay time ΔT is obtained and corrected based on the above. In claim 6,
The ejection timing correction means detects a change in the distance between the print head and the recording medium due to the landing of ink in the forward printing during the backward printing, and determines the ejection timing of the backward printing based on the change in the distance. An ink jet recording apparatus which is means for correcting. In an inkjet recording apparatus that uses a print head that discharges ink and discharges and records ink from the print head to a recording medium.
A tip distance detection sensor provided at the tip of the print head, the tip distance detecting sensor detecting a tip distance that is a distance from the recording medium;
A rear end distance detecting sensor provided at a rear end of the print head, the rear end distance detecting sensor detecting a rear end distance which is a distance from the recording medium;
An inclination angle detecting means for detecting an inclination angle of the print head with respect to the recording medium based on the detected leading edge distance and trailing edge distance;
Discharge timing correction means for correcting the timing of discharging ink from the nozzles based on the detected inclination angle and the moving speed of the carriage in the discharge section;
An ink jet recording apparatus, wherein the leading edge distance detection sensor and the trailing edge distance detection sensor are optical sensors. In a control method of an inkjet recording apparatus that uses a print head that discharges ink and discharges and records ink from the print head to a recording medium,
A step of detecting a tip distance, which is a distance between the print head and the recording medium, by a tip distance detection sensor provided at a tip portion in the transport direction of the print head;
A step of a rear end distance detection sensor provided at a rear end in the transport direction of the print head detecting a rear end distance which is a distance between the print head and the recording medium;
An inclination angle detecting step of detecting an inclination angle of the nozzle surface of the recording head with respect to the conveyance direction based on the detected leading edge distance and trailing edge distance;
An ejection timing correction step of correcting the timing of ejecting ink from the nozzles based on the detected inclination angle and the moving speed of the carriage in the ejection section;
A method for controlling an ink jet recording apparatus, comprising:

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