JP2009255305A - Recording apparatus and recording control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that in a serial inkjet recording apparatus, a failure in the measurement of the moving speed of a recording medium by a laser Doppler velocimeter occurs, an error occurs in the conveyance amount of the recording medium by the influence of the eccentricity, etc. of a conveying roller due to the failure and a recording dot position is deviated to deteriorate an image. <P>SOLUTION: The conveyance amount of a recording paper is detected from the output information of a rotary encoder attached to the conveying roller and information where a low frequency component is extracted from the output of the laser Doppler velocimeter detecting the moving speed of the recording paper, to perform control for reducing the deviation of the recording dot position. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a recording apparatus and a conveyance control method. In particular, the present invention relates to a recording apparatus and a recording control method for controlling the conveyance of a recording medium while detecting the conveyance position of the recording medium using, for example, a rotary encoder.

  In recent years, digital copying machines and printers have been rapidly put into practical use. Particularly, digital color printers and color copying machines take advantage of digital features such as easy color adjustment and image processing. It is becoming mainstream in the field of printers and color copiers.

  As recording methods of these recording apparatuses, there are various methods such as an electrophotographic method, an ink jet method, and a thermal transfer method. Among them, an ink jet recording apparatus performs recording by ejecting ink from a recording head onto a recording medium. The recording head can be easily made compact, and high-definition images can be recorded at high speed. In addition, the running cost is low, and the non-impact method is advantageous in that the noise is low and it is easy to record a color image using multi-color ink.

  In order to convey a recording medium with high accuracy, a conventional inkjet recording apparatus (hereinafter referred to as a recording apparatus) is provided with a rotary encoder at one end of a conveyance roller that conveys the recording medium, and detects the conveyance position of the recording medium. ing.

  The rotary encoder includes an encoder wheel provided with a scale at every fixed angle and an encoder sensor for detecting the scale of the encoder wheel. When the transport roller is driven with the rotation of the transport motor, a pulse signal synchronized with the scale is output from the encoder sensor. When transporting the recording medium, the pulse signals output from the encoder sensor are counted, and the transport motor is driven so that the recording medium is transported by a desired distance. Note that, depending on the type of recording medium, there are some cases in which the conveyance amount differs even when the same number of encoder pulses are counted due to the friction coefficient between the recording medium and the conveyance roller being different. In this case, according to the type of the recording medium, the relationship between the carry amount and the encoder pulse is corrected to drive the carry motor.

  As described above, when the recording medium is transported, the transport motor is driven based on the angular displacement of the transport roller detected by the rotary encoder provided on the shaft of the transport roller. For example, when a rotary roller having an outer circumference of 25.4 mm and an output per revolution of 1200 pulses is used, in order to convey the recording medium by 4.23 mm, the conveyance motor is only output 200 pulses from the encoder. Will drive.

  However, in reality, due to the influence of manufacturing errors (eccentricity, roundness, etc.) of the transport roller, even if the transport roller is rotated by a certain angle, the transport distance of the recording medium varies.

  FIG. 9 is a diagram showing the measurement result of the speed fluctuation of the recording medium when the conveying roller having an outer circumference of 50.8 mm is rotated at a constant angular speed of about 125 rpm and the recording medium is continuously conveyed.

  This figure shows the fluctuation ratio with respect to the ideal recording medium speed V (= 50.8 × 125 / 60≈105.8 mm / sec). That is, a fluctuation ratio of 0 [%] indicates an ideal recording medium conveyance speed.

  Now, it can be seen from FIG. 9 that there is a large speed fluctuation with a period of 0.48 sec. On the other hand, the relationship between the ideal recording medium speed V and the outer circumference L of the conveying roller is L / V = 50.8 / 105.8 = 0.48. Therefore, the value of 0.48 sec is a period of one rotation of the conveying roller, and it can be understood that the speed fluctuation of the illustrated 0.48 sec period is caused by the eccentricity of the conveying roller. In addition, the speed fluctuation shown in the figure is most noticeable with a period of 0.48 sec. However, since this is not the only case, the speed fluctuation due to factors other than the eccentricity of the conveying roller (for example, due to a slight slip between the recording medium and the conveying roller). It is thought that there is)).

  Thus, even if the conveyance roller is driven at an equal angular speed, the conveyance speed of the recording medium is not equal. That is, the relationship between the output of the rotary encoder that detects the angular displacement of the conveyance roller and the conveyance distance of the recording medium is not constant but varies. Therefore, if the output amount of the rotary encoder provided on the shaft of the transport roller is counted to control the transport amount of the recording medium, an error occurs in the transport amount of the recording medium. The same problem also occurs when a pulse motor is used as the conveyance motor for driving the conveyance roller and the conveyance amount of the recording medium is controlled by the number of pulses input to the pulse motor.

  When there is an error in the transport amount of the recording medium, the positional relationship between the recording dots recorded before transporting the recording medium at a certain timing and the recording dots recorded after transporting the recording medium is the error that occurred in the transport amount of the recording medium. It will shift. If the position of the recording dot is shifted, white streaks, black streaks and density unevenness occur, and the recorded image deteriorates.

  As described above, when the conveyance control of the recording medium is performed based on the angular displacement of the conveyance roller, the image deterioration occurs due to the influence of the eccentricity of the conveyance roller.

  In order to improve such a problem, a test pattern is conventionally recorded by a recording apparatus, the amount of eccentricity of the conveyance roller is estimated from the pattern, and the amount of eccentricity estimated when the recording medium is conveyed is obtained. Based on this, a method for correcting the driving amount of the transport roller has been proposed (Patent Document 1).

In addition, a method has been proposed in which the positional deviation of the recording dots is prevented by detecting the speed of the recording medium instead of estimating the eccentric amount of the conveying roller (Patent Document 2). Patent Document 2 proposes a method of detecting a moving speed of a conveying belt with a laser Doppler velocimeter in a line type recording apparatus that conveys a recording medium using a conveying belt. Patent Document 2 mainly describes a line type recording apparatus, but the present invention can also be applied to a serial type recording apparatus in that the conveyance speed of the recording medium is detected.
JP 2006-224380 A Japanese Patent No. 3039703

  However, the above conventional example has the following problems.

  The method disclosed in Patent Document 1 is feedforward control based on information detected and stored in the past. Therefore, it is an effective method when the conveyance of the recording medium fluctuates in synchronization with the rotation period of the conveyance roller as in the past detection, but when the cause of the fluctuation is different from the past detection. Cannot remove the effect.

  For example, deformation of the conveyance roller accompanying continuous use of the apparatus, expansion or contraction of the conveyance roller due to temperature change inside the apparatus, or slight slip between the conveyance roller and the recording medium that is not synchronized with the rotation cycle of the conveyance roller, etc. If this occurs, the error in conveying the recording medium cannot be corrected sufficiently. Increasing the detection frequency of the recording medium conveyance fluctuation can improve the correction accuracy against deformation of the conveyance roller due to continuous use of the apparatus and expansion / contraction of the conveyance roller due to temperature change inside the apparatus. Is possible. However, in this case, in addition to increasing the downtime of the recording apparatus and reducing the throughput, another problem arises that the consumption of recording paper and ink used for detection increases.

  Further, when the relationship between the rotation angle of the conveyance roller and the conveyance distance of the recording medium differs depending on the type of the recording medium, the correction process is necessary. However, when the type of the recording medium cannot be accurately recognized, a desired distance is obtained. Only the recording medium can not be transported and corrected.

  Further, the method disclosed in Patent Document 2 performs the feedback control while directly detecting the change in the conveyance speed of the recording medium, and thus the above-described problem does not occur. However, the laser Doppler velocimeter employed in the method of Patent Document 2 has the following problems.

  Before describing the problem, a laser Doppler velocimeter will be described.

  FIG. 10 is a block diagram showing the configuration of the laser Doppler velocimeter.

  In laser Doppler velocimeter 400 shown in FIG. 10, first, laser light LA is emitted from laser light source 401. The irradiated laser beam LA is divided into two at the beam splitter 402. One laser beam L1 passes through the beam splitter 402 and directly irradiates the object to be measured 410. On the other hand, the other laser beam L2 is reflected by the beam splitter 402, and further reflected by the reflecting mirror 403 to irradiate the object 410 to be measured. As shown in FIG. 10, the laser beams L1 and L2 are incident on the perpendicular to the measured object 410 at an incident angle θ, that is, irradiate the measured object 410 symmetrically with respect to the perpendicular.

  Here, when the laser beams L1 and L2 are incident on the measurement object 410 moving at the velocity V, the measurement object 410 scatters the laser beams L1 and L2 and emits the scattered light LB. The scattered light LB passes through the optical system such as the condenser lens 404 and reaches the light receiving sensor 405. The light receiving sensor 405 detects the scattered light LB and performs photoelectric conversion. Thereby, the amplitude of the scattered light is converted into an electric signal and input to the amplifier 406. The amplifier 406 amplifies the amplitude of the electrical signal picked up by the light receiving sensor 405 and outputs it to the bandpass filter 407. The bandpass filter 407 performs heterodyne detection, and as a result, obtains a Doppler signal D that is an analog signal.

  The Doppler signal D is obtained by electrically extracting a beat signal (beat) generated when the two laser beams L1 and L2 are scattered by the measurement object 410 moving at the velocity V. The frequency fD of the Doppler signal D is expressed by Equation (1) from the velocity V of the measurement object 410, the incident angle θ, and the wavelength λ of the laser beam.

fD = 2V · sin θ / λ (1)
From the equation (1), by using the set incident angle θ, the wavelength λ of the laser beam, and the frequency fD observed from the waveform of the Doppler signal D, the speed of the DUT 410 can be obtained.

  On the other hand, the laser Doppler velocimeter 400 inputs the Doppler signal D to the signal processing circuit 408. The signal processing circuit 408 converts the Doppler signal D having a frequency of fD into a pulse signal having the same frequency of fD, and outputs this signal as a speed signal.

  That is, as shown in OUTPUT in FIG. 10, this signal is a pulse signal whose period is expressed by the equation (2).

T (= 1 / fD) (2)
The period T can be written as Expression (3) from Expression (1) and Expression (2).

T = λ / (2V · sin θ) (3)
Therefore, the period T is inversely proportional to the speed V of the object to be measured 410.

  Further, when Expression (3) is modified, Expression (4) is obtained.

T · V = λ / (2 · sinθ) (4)
The value obtained by multiplying the velocity V and the period T has a dimension of length (distance), and λ / (2 · sin θ) on the right side of the equation (4) is a constant value (constant value determined by the design specification of the laser Doppler velocimeter 400 Distance L).

Therefore, if L is an expression (5),
L≡λ / (2 · sinθ) (5)
The period T of the pulse signal indicates the time for the DUT 410 to travel a certain distance L.

  In other words, the rising edge of the pulse signal occurs each time the DUT 410 travels a certain distance L. For example, when the laser wavelength λ = 800 nm and sin θ = 1/4, the size of the constant distance L is L = 1.6 μm. That is, the rising edge of the pulse signal indicates a displacement every L = 1.6 μm, and a very precise displacement can be detected.

  In this way, the laser Doppler velocimeter 400 outputs a pulse signal capable of detecting a precise displacement in real time as a speed signal, in other words, a time (period T) during which the measured object 410 travels a certain distance L. Is output in real time as a speed signal.

  In Patent Document 2, the speed of the conveyor belt is detected using the laser Doppler velocimeter described above. However, although not described in detail in Patent Document 2, since the laser Doppler velocimeter detects the speed in a non-contact manner, the Doppler signal weakens momentarily depending on the surface condition of the object to be measured, and the output is lost (hereinafter referred to as dropout). ).

  The dropout of the laser Doppler velocimeter will be described with reference to the drawings.

  FIG. 11 is a diagram showing a measurement result of a laser Doppler velocimeter with an output resolution of 1.25 μm when a conveyance medium having an outer circumference of 50.8 mm is rotated at an equal angular speed of about 125 rpm to convey a recording medium.

  Here, FIG. 11A is a pulse waveform output from the laser Doppler velocimeter, and FIG. 11B is a plot of the time between the rising and falling edges of the output pulse waveform. .

  The output of the laser Doppler velocimeter used for this measurement changes in level from “High” to “Low” or from “Low” to “High” every 1.25 μm. Therefore, the normal pulse half cycle T (period of “High” or “Low”) is as follows if the eccentricity of the roller is ignored.

T = f / V
= 1.25 (μm) / {50.8 (mm) × 125 (rpm) / 60 (sec)}
≒ 11.8 (μsec)
Here, f is the output resolution and V is the moving speed of the recording medium.

  According to the measurement performed separately, the speed fluctuation due to the eccentricity of the conveyance roller used for the measurement is within ± 5%. On the other hand, since the speed fluctuation between 150 μsec and 900 μsec shown in FIG. 11 is ± 5% or more, it can be understood that the cause is not the speed fluctuation of the recording medium but the effect of dropout.

  As described above, since dropout generally occurs in the laser Doppler velocimeter, the speed of the conveyor belt detected by the laser Doppler velocimeter as in Patent Document 2 includes an error due to the influence of dropout. End up.

  Even if the conveyor belt is scaled and read by an optical sensor instead of a laser Doppler velocimeter, if the conveyor belt scale becomes dirty, the detection signal will still be missing and detected. An error occurs in speed.

  The present invention has been made in view of the above-described conventional example. Even when a missing recording medium moving speed is detected, fluctuations in the recording medium conveyance speed are detected, and high-precision conveyance control and high-quality image recording are performed. It is an object of the present invention to provide a possible recording apparatus and recording control method.

  In order to achieve the above object, the recording apparatus of the present invention has the following configuration.

  That is, a recording apparatus that performs recording on a recording medium by scanning a recording head having a row of recording elements composed of a plurality of recording elements, the conveying roller conveying the recording medium, and the driving force of the conveying roller A transport motor for generating the transport motor, a driving means for driving the transport motor, a rotary encoder that is provided at one end of the transport roller and outputs a rotation signal indicating the position of the transport roller according to the rotation of the transport roller, Detecting means for detecting a moving speed of a recording medium; correcting means for correcting a moving signal representing the moving speed based on the rotation signal, the moving speed, and motor control information output from the driving means; Generation means for generating long-period fluctuation information about the movement speed based on the movement signal corrected by the correction means and the motor control information; Calculation means for calculating a deviation amount of the conveyance of the recording medium based on the long period fluctuation information generated by the generation means and the rotation signal; and a deviation of the conveyance of the recording medium calculated by the calculation means. Control means for determining a recording element to be used for recording from the plurality of recording elements based on the amount and controlling the recording to be performed on the recording medium by the determined recording element.

  According to another invention, a recording head having a row of recording elements composed of a plurality of recording elements is scanned, while the recording medium is conveyed to the recording medium while being conveyed by a conveying roller using a driving force generated by a conveying motor. A recording control method for a recording apparatus that performs recording on a recording apparatus, the detection being performed by a rotation signal from a rotary encoder provided at one end of the conveyance roller and detecting the position of the conveyance roller according to the rotation of the conveyance roller, and detection means A correction step for correcting a movement signal representing the movement speed based on the movement speed of the recording medium that has been performed and motor control information output from a motor driver that drives the conveyance motor, and correction in the correction step Based on a movement signal and the motor control information, a generation step for generating long-period fluctuation information about the movement speed; A calculation step of calculating a deviation amount of the conveyance of the recording medium based on the long period fluctuation information generated in the generation step and the rotation signal, and a deviation of the conveyance of the recording medium calculated in the calculation step. And a control step of determining a recording element to be used for recording from the plurality of recording elements based on the quantity and controlling the recording to be performed on the recording medium by the determined recording element. A control method is provided.

  Therefore, according to the present invention, even if the detection of the moving speed of the recording medium is lost, the influence can be reduced and the conveying speed of the recording medium can be detected with high accuracy. Thereby, for example, it is possible to reduce the positional deviation of the recording dots that occurs due to fluctuations in the conveyance speed of the recording medium due to the eccentricity of the conveyance rollers, and to realize high-quality image recording.

  Hereinafter, preferred embodiments of the present invention will be described more specifically and in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the already demonstrated part and duplication description is abbreviate | omitted.

  In this specification, “recording” (sometimes referred to as “printing”) is not limited to the case of forming significant information such as characters and graphics, but may be significant. It also represents the case where an image, a pattern, a pattern, etc. are widely formed on a recording medium, or the medium is processed, regardless of whether it is manifested so that humans can perceive it visually. .

  “Recording medium” refers not only to paper used in general recording apparatuses but also widely to cloth, plastic film, metal plate, glass, ceramics, wood, leather, and the like that can accept ink. Shall.

  Further, “ink” (sometimes referred to as “liquid”) should be interpreted widely as in the definition of “recording (printing)”. Therefore, by being applied on the recording medium, it is used for formation of images, patterns, patterns, etc., processing of the recording medium, or ink processing (for example, solidification or insolubilization of the colorant in the ink applied to the recording medium). It shall represent a liquid that can be made.

  Furthermore, unless otherwise specified, the “recording element” collectively refers to an ejection port or a liquid path communicating with the ejection port and an element that generates energy used for ink ejection.

<Description of Inkjet Recording Apparatus (FIG. 1)>
FIG. 1 is an external perspective view showing an outline of the configuration of an ink jet recording apparatus 1 which is a typical embodiment of the present invention.

  As shown in FIG. 1, an ink jet recording apparatus (hereinafter referred to as a recording apparatus) has a recording head 3 mounted on a carriage 2 for performing recording by discharging ink according to an ink jet system. A driving force generated by the carriage motor M1 is transmitted to the carriage 2 from the transmission mechanism 4, and the carriage 2 is reciprocated in the arrow A direction. At the time of recording, for example, a recording medium P such as recording paper is fed through the paper feeding mechanism 5 and conveyed to a recording position, and recording is performed by ejecting ink from the recording head 3 to the recording medium P at the recording position. Do.

  Further, in order to maintain the state of the recording head 3 satisfactorily, the carriage 2 is moved to the position of the recovery device 10 and the ejection recovery process of the recording head 3 is intermittently performed.

  In addition to mounting the recording head 3 on the carriage 2 of the recording apparatus 1, an ink cartridge 6 for storing ink to be supplied to the recording head 3 is mounted. The ink cartridge 6 is detachable from the carriage 2.

  The recording apparatus 1 shown in FIG. 1 is capable of color recording. For this reason, the carriage 2 contains four inks containing magenta (M), cyan (C), yellow (Y), and black (K) inks, respectively. An ink cartridge is installed. These four ink cartridges are detachable independently.

  Now, the carriage 2 and the recording head 3 can achieve and maintain a required electrical connection by properly contacting the joint surfaces of both members. The recording head 3 applies energy according to a recording signal to selectively eject ink from a plurality of ejection ports for recording. In particular, the recording head 3 of this embodiment employs an ink jet system that ejects ink using thermal energy. For this reason, the recording head 3 is provided with an electrothermal transducer for generating thermal energy. The electrical energy applied to the electrothermal converter is converted to thermal energy, and the ink is ejected from the discharge port using the pressure change caused by the growth and contraction of bubbles caused by film boiling caused by applying the thermal energy to the ink. To discharge. The electrothermal transducer is provided corresponding to each of the ejection ports, and ink is ejected from the corresponding ejection port by applying a pulse voltage to the corresponding electrothermal transducer in accordance with the recording signal.

  As shown in FIG. 1, the carriage 2 is connected to a part of the driving belt 7 of the transmission mechanism 4 that transmits the driving force of the carriage motor M <b> 1, and slides in the direction of arrow A along the guide shaft 13. It is guided and supported freely. Accordingly, the carriage 2 reciprocates along the guide shaft 13 by forward and reverse rotations of the carriage motor M1. A scale 8 is provided for indicating the absolute position of the carriage 2 along the moving direction of the carriage 2 (arrow A direction, scanning direction). In this embodiment, the scale 8 uses a transparent PET film on which black bars are printed at the necessary pitch, one of which is fixed to the chassis 9 and the other is supported by a leaf spring (not shown). Yes.

  Further, the recording apparatus 1 is provided with a platen (not shown) facing the discharge port surface where the discharge port (not shown) of the recording head 3 is formed. Then, the carriage 2 on which the recording head 3 is mounted is reciprocated by the driving force of the carriage motor M1, and at the same time, a recording signal is given to the recording head 3 to eject ink, thereby conveying the recording medium P conveyed onto the platen. Recording is performed over the full width.

  Further, in FIG. 1, reference numeral 14 denotes a conveyance roller driven by a conveyance motor M2 to convey the recording medium P, and 15 denotes a pinch roller that abuts the recording medium P against the conveyance roller 14 by a spring (not shown). Reference numeral 16 denotes a pinch roller holder that rotatably supports the pinch roller 15, and reference numeral 17 denotes a conveyance roller gear fixed to one end of the conveyance roller 14. Then, the transport roller 14 is driven by the rotation of the transport motor M2 transmitted to the transport roller gear 17 through an intermediate gear (not shown).

  As will be described later, one end of the transport roller 14 is provided with a rotary encoder including an encoder wheel provided with a scale at every fixed angle and an encoder sensor for detecting the scale of the encoder wheel. When the transport roller 14 is driven with the rotation of the transport motor M2, a pulse signal synchronized with the scale is output from the encoder sensor. When transporting the recording medium P, transport control is performed based on a pulse signal output from the encoder sensor.

  Further, reference numeral 20 denotes a discharge roller for discharging the recording medium P on which an image is formed by the recording head 3 to the outside of the recording apparatus, and is driven by transmitting the rotation of the transport motor M2. . The discharge roller 20 abuts on a spur roller (not shown) that presses the recording medium P by a spring (not shown). Reference numeral 22 denotes a spur holder that rotatably supports the spur roller.

  Furthermore, the recording apparatus 1 includes a recording head at a desired position (for example, a position corresponding to the home position) outside the range of reciprocal motion for recording operation of the carriage 2 on which the recording head 3 is mounted (outside the recording area). A recovery device 10 for recovering the ejection failure 3 is provided.

  The recovery device 10 includes a capping mechanism 11 for capping the ejection port surface of the recording head 3 and a wiping mechanism 12 for cleaning the ejection port surface of the recording head 3. In conjunction with capping of the ejection port surface by the capping mechanism 11, ink is forcibly discharged from the ejection port by a suction means (suction pump or the like) in the recovery device, and the viscosity in the ink flow path of the recording head 3 is increased. The ejection recovery process such as removing the ink and bubbles is performed.

  Further, when the recording head 3 is not in operation or the like, the ejection port surface of the recording head 3 is capped by the capping mechanism 11 to protect the recording head 3 and to prevent ink evaporation and drying. On the other hand, the wiping mechanism 12 is disposed in the vicinity of the capping mechanism 11 and wipes ink droplets adhering to the ejection port surface of the recording head 3.

  The capping mechanism 11 and the wiping mechanism 12 can keep the ink ejection state of the recording head 3 normal.

<Control Configuration of Inkjet Recording Apparatus (FIG. 2)>
FIG. 2 is a block diagram showing a control configuration of the recording apparatus shown in FIG.

  As shown in FIG. 2, the controller 600 includes an MPU 601, a ROM 602, a special purpose integrated circuit (ASIC) 603, a RAM 604, a system bus 605, an A / D converter 606, and the like. Here, the ROM 602 stores a program corresponding to a control sequence to be described later, a required table, and other fixed data. The ASIC 603 generates control signals for controlling the carriage motor M1, the transport motor M2, and the recording head 3. The RAM 604 is used as a development area for image data, a work area for program execution, and the like. A system bus 605 connects the MPU 601, the ASIC 603, and the RAM 604 to each other to exchange data. The A / D converter 606 inputs analog signals from the sensor group described below, performs A / D conversion, and supplies a digital signal to the MPU 601.

  In FIG. 2, reference numeral 610 denotes a computer (or a reader for image reading, a digital camera, etc.) serving as a supply source of image data, and is collectively referred to as a host device. Image data, commands, status signals, and the like are transmitted and received between the host apparatus 610 and the recording apparatus 1 via an interface (I / F) 611. This image data is input in a raster format, for example.

  Reference numeral 620 denotes a switch group, which includes a power switch 621, a print switch 622, a recovery switch 623, and the like.

  Reference numeral 630 denotes a sensor group for detecting the apparatus state, and includes a position sensor 631, a temperature sensor 632, and the like.

  Further, 640 is a carriage motor driver that drives a carriage motor M1 for reciprocating scanning of the carriage 2 in the direction of arrow A, and 642 is a conveyance motor driver that drives a conveyance motor M2 for conveying the recording medium P.

  The ASIC 603 transfers drive data (DATA) of the printing element (ejection heater) to the printing head while directly accessing the storage area of the RAM 604 during printing scanning by the printing head 3.

  The configuration shown in FIG. 1 is a configuration in which the ink cartridge 6 and the recording head 3 can be separated, but a replaceable head cartridge may be configured by integrally forming them.

  Next, some examples of the conveyance control executed in the recording apparatus having the above configuration will be described.

  FIG. 3 is a block diagram illustrating a configuration of the conveyance control according to the first embodiment.

  In FIG. 3, the recording head 3 includes a nozzle array composed of a plurality of nozzles arranged in a direction substantially parallel to the conveyance direction of the recording medium P, and ejects ink droplets from the nozzle array while scanning in the depth direction of the drawing. Make a record. In FIG. 3, the same components as those already described in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  The transport roller 14 is driven by the rotation of the transport motor M2 transmitted through the belt member 105 as driving force transmitting means, and the recording medium P is transported accordingly. One end of the conveying roller 14 is provided with a rotary encoder 110 as a roller rotation signal generating means comprising an encoder wheel 108 provided with a scale at every fixed angle and an encoder sensor 109 for detecting the scale of the encoder wheel 108. ing. When the transport roller 14 is driven, a pulse signal is output from the rotary encoder 110 at every predetermined angular rotation.

  In the recording apparatus shown in FIG. 1, the transport motor driver 642 outputs a rotation command signal to the transport motor M2 according to a desired speed profile, and rotates the transport motor M2. The transport motor driver 642 receives the pulse signal output from the rotary encoder 110, and counts the input pulse signal to control the rotation amount of the transport motor M2. In this way, the recording medium P is transported by a predetermined amount by rotating the transport motor M2 by a predetermined amount, and then a single recording operation is performed by ejecting ink droplets while scanning the recording head 3.

  The recording medium P is in contact with the discharge roller 20 by a spur roller 107.

  As shown in FIG. 3, a platen member 112 having an opening is disposed at a position facing the nozzle formation surface of the recording head. Further, a laser Doppler velocimeter 111 is provided as a recording medium movement signal generation unit, and detects the conveyance speed of the recording medium P conveyed on the platen member by irradiating laser light from the opening of the platen member 112. From the laser Doppler velocimeter 111, a pulse signal is output every time the recording medium P advances a certain distance.

  Note that an opening / closing shutter member (not shown) is provided in the opening of the platen member 112, and the shutter member is closed when the laser Doppler velocimeter 111 does not detect the conveyance speed of the recording medium P. This prevents the laser Doppler velocimeter 110 from being contaminated by ink droplets ejected from the recording head 3 or ink mist floating in the recording apparatus.

  The signal output from the rotary encoder 110 and the signal output from the laser Doppler velocimeter 111 are input to the controller 600. Further, motor control information is input to the controller 600 from the transport motor driver 642.

  Functionally, the controller 600 includes a recording medium movement signal correction unit 120 as a signal correction unit, a long period information generation unit 130 as a variation information generation unit, and a conveyance amount information calculation unit 140 as a conveyance amount information generation unit. It is provided and used for transport control of the recording medium. These functional units are realized as a part of a control program executed by the MPU 601 or a part of a logic circuit executed by the ASIC 603.

  The conveyance information generation unit 113 will be described in detail later.

  Conveyance amount error information is output from the conveyance information generation unit 113 and input to the head driver 644. Here, the conveyance amount error information is information representing a deviation amount with respect to an ideal conveyance amount (when there is no eccentricity of the conveyance roller).

  The head driver 644 determines the driving range of the nozzle row in accordance with the input carry amount error information, and drives the recording head 3 to perform recording.

  For example, it is assumed that the recording head includes a nozzle row in which 512 nozzles are arranged at an interval of 1200 dpi. Here, for the sake of explanation, the nozzles are referred to as nozzle 1, nozzle 2,..., Nozzle 512 in order from the upstream side in the conveyance direction of the recording medium.

  First, when the carry amount error information is “0 μm”, that is, when the deviation from the ideal carry amount is 0 μm, the drive range of the nozzle row is determined to be 480 nozzles from nozzle 17 to nozzle 496. Then, recording is performed by ejecting ink droplets from the 480 nozzles based on the image data.

  On the other hand, when the transport amount error information is “+63 μm”, that is, when the transport amount has been transported by 63 μm more than the ideal transport amount, the drive range of the nozzle row is increased to 480 nozzles from nozzle 20 to nozzle 499. decide. Then, recording is performed by ejecting ink droplets from the 480 nozzles based on the image data.

  Similarly, when the carry amount error information has other values, the driving range of the nozzle row is determined so that printing can be performed at a position closest to the ideal recording dot position. By doing so, the amount of deviation of the recording dot from the ideal position can be suppressed to ½ or less of the resolution of the nozzle array, and image deterioration due to the displacement of the recording dot is reduced.

  Now, the conveyance information generation function unit of the controller 600 which is a characteristic configuration of this embodiment will be described in detail.

  FIG. 4 is a block diagram illustrating a functional configuration of the transport information generation function unit.

  As shown in FIG. 4, a recording medium movement signal (hereinafter, movement signal) output from the laser Doppler velocimeter 111 is input to the first input terminal 101. The movement signal is a pulse signal that generates a rising edge every time the recording medium P moves by a certain amount. Since the movement signal is an output signal of the laser Doppler velocimeter 111, dropout may occur as described above. Motor control information output from the transport motor driver 642 is input to the second input terminal 102. The motor control information is information indicating at what speed the motor is driven. A roller rotation signal output from the rotary encoder 110 is input to the third input terminal 103. The roller rotation signal is a pulse signal that generates a rising edge every time the transport roller 14 rotates by a certain angle. The rotary encoder 110 has a home position, and a pulse signal indicating the home position is generated every time the rotary encoder 110 makes one round.

  A recording medium movement signal correction unit (hereinafter, correction unit) 120 is a processing unit that corrects a dropout generated in the laser Doppler velocimeter 111. The correction unit 120 determines that there is an abnormality when the pulse period of the input movement signal is outside the assumed range, and performs correction processing.

  The correction unit 120 includes a recording medium movement signal cycle detection unit (hereinafter referred to as a cycle detection unit) 121, a recording medium movement signal state determination unit (hereinafter referred to as a state determination unit) 122, and a recording medium movement signal state determination criterion storage unit (hereinafter referred to as a recording medium movement signal state determination reference storage unit). , State determination reference storage unit) 123. Further, the correction unit 120 includes a recording medium movement signal cycle correction unit (hereinafter referred to as a cycle correction unit) 124 and a recording medium movement signal cycle correction value storage unit (cycle correction value storage unit) 125. Furthermore, the correction unit 120 includes a recording medium movement signal correction information generation unit (correction information generation unit) 126, a roller phase detection unit 127, a roller phase information storage control unit 128, and a roller phase information storage unit 129. .

  The period detection unit 121 detects the generation period of the rising edge of the input movement signal, and outputs this as pulse period information every time the rising edge of the movement signal occurs.

  The pulse period information output from the period detection unit 121 is input to the state determination unit 122. The state determination unit 122 compares the determination reference information (upper limit value and lower limit value of the pulse period) stored in the state determination reference storage unit 123 with the input pulse period information. When the input pulse period information is within the range, it is determined that the input pulse period information is normal, and when it is out of the range, the recording medium movement signal state determination information is determined to be determined as abnormal.

  When the recording medium movement signal state determination information output from the state determination unit 122 indicates “normal”, the period correction unit 124 outputs the input pulse period information as it is as corrected pulse period information. On the other hand, when the recording medium movement signal state determination information indicates “abnormal”, the input pulse period information is replaced with the correction period information stored in the period correction value storage unit 125, and this is corrected pulse. Output as period information.

  Note that the determination reference information stored in the state determination reference storage unit 123 and the correction cycle information stored in the cycle correction value storage unit 125 are generated by the correction information generation unit 126.

  First, the roller phase detector 127 detects and outputs the roller phase information of the transport roller 14 from the roller rotation signal input from the third input terminal 103. The output roller phase information is input to the roller fluctuation information storage control unit 128. In the roller fluctuation information storage control unit 128, the roller fluctuation information storage unit 129 uses the pulse period information in each roller phase as roller fluctuation information in accordance with the input roller phase information and the corrected pulse period information input from the period correction unit 124. To remember. Further, the roller fluctuation information storage control unit 128 reads out the roller fluctuation information stored one revolution before the conveyance roller from the roller fluctuation information storage unit 129 and outputs it to the correction information generation unit 126 according to the input roller phase information. .

  The correction information generation unit 126 generates determination criterion information and correction cycle information from the input roller fluctuation information and the motor control information input from the second input terminal 102. Specifically, for example, a value of ± 5% of the roller fluctuation information input from the roller fluctuation information storage control unit 128 is set as the upper limit value and the lower limit value of the determination reference, and the roller fluctuation information itself is set as the correction cycle information. The determination reference storage unit 123 and the period correction value storage unit 125 are stored.

  In this way, the reference value used for determining the recording medium movement signal state and the recording medium movement signal period correction value used for correcting the recording medium movement signal period are conveyed even during acceleration and deceleration during the conveyance of the recording medium. Updated / referenced in synchronization with the motor driver 642. Thereby, the correction process of the movement signal is performed.

  Here, a configuration has been described in which the recording medium movement signal state determination can be performed with high accuracy, but it is also possible to generate the determination reference information and the correction cycle information simply from the motor control information.

  Further, when the conveyance roller 14 is accelerated or decelerated, a delay occurs until the conveyance roller 14 reacts to the rotation command from the conveyance motor driver 642. Therefore, the determination criterion information particularly at the time of acceleration / deceleration has a larger range for determining normal It is preferable to perform exception processing such as.

  In this way, the correction unit 120 performs a correction process for dropout generated in the laser Doppler velocimeter 111 and outputs post-correction pulse period information.

  The corrected pulse period information output from the correction unit 120 is input to the long period information generation unit 130. The long cycle information generation unit 130 detects fluctuation information having a relatively long cycle from the input corrected pulse cycle information.

  The long cycle information generation unit 130 includes a recording medium movement signal cycle average value calculation unit (hereinafter referred to as a cycle average value calculation unit) 131, a recording medium movement signal averaged interval storage unit (hereinafter referred to as an averaged interval storage unit) 132, A recording medium movement signal fluctuation information calculation unit (hereinafter referred to as a fluctuation information calculation unit) 133.

  In the period average value calculation unit 131, the corrected pulse period input from the correction unit 120 based on the recording medium movement signal averaging section information (hereinafter, averaged section information) stored in the averaging section storage unit 132. The average value of information is calculated. For example, when the averaged interval information stored in the averaged interval storage unit 132 is “200 μm” and the output resolution of the laser Doppler velocimeter 111 is “2 μm”, the average value for 100 corrected pulse period information Is calculated. The average value is output as recording medium movement signal cycle average value information (hereinafter, cycle average value information). Note that the averaged section information stored in the averaged section storage unit 132 may always be a constant value or a different value depending on the conveyance speed of the recording medium.

  The period average value information output from the period average value calculation unit 131 is input to the fluctuation information calculation unit 133. In the fluctuation information calculation unit 133, an ideal recording medium movement signal pulse cycle calculated from the motor control information input from the second input terminal 102, and the cycle average value information output from the cycle average value calculation unit 131, Then, the movement amount variation rate information of the recording medium is calculated and output. r The ideal pulse period is the period when there is no eccentricity of the transport roller.

  In this way, the long period information generation unit 130 extracts the long period component of the movement amount fluctuation of the recording medium and outputs it as movement amount fluctuation rate information.

  The movement amount variation rate information output from the long cycle information generation unit 130 is input to the transport amount information calculation unit 140. In the carry amount information calculation unit 140, the deviation amount with respect to the ideal carry amount of the recording medium from the roller rotation signal inputted from the third input terminal 103 and the movement amount variation rate information inputted from the long period information generation unit 130. Is output.

  The transport amount information calculation unit 140 includes a roller rotation signal edge detection unit 141, a transport movement amount error value calculation unit 142, and a transport movement amount error integration unit 143.

  The roller rotation signal edge detection unit 141 detects a rising edge of the roller rotation signal input from the third input terminal 103, and outputs a pulse signal each time a rising edge is detected. The transport movement amount error value calculation unit 142 calculates and outputs a recording medium movement amount error value per pulse of the roller rotation signal based on the movement amount variation rate information input from the long cycle information generation unit 130. The transport movement amount error integration unit 143 integrates the recording medium movement amount error value output from the transport movement amount error value calculation unit 142 each time a pulse signal is input from the roller rotation signal edge detection unit 141. For a period in which the recording medium is transported once during the recording operation, the transport movement amount error integration unit 143 integrates the recording medium movement amount error value, thereby calculating a deviation amount of the transport amount in one transport operation.

  The transport amount error information calculated in this way is output from the output terminal 104.

  The output carry amount error information is input to the head driver 644 shown in FIG. 3, and the nozzle row drive range is determined based on the carry amount error information as described above, thereby reducing recording dot positional deviation. To do.

  Therefore, according to the embodiment described above, the long period component of the speed fluctuation of the recording medium is extracted, and the conveyance amount of the recording medium is calculated together with the rotation amount of the conveyance roller. As a result, the influence of the eccentricity of the transport roller can be reduced, and even if a defect occurs in the speed detection of the recording medium, the influence can be reduced and the position control of the recording dots can be performed, so that high-quality image formation Is possible.

  In this embodiment, since the moving speed of the recording medium is directly detected, the conveyance amount is corrected according to the type of the recording medium as in the case where the conveyance amount of the recording medium is controlled from the rotary encoder. There is also an advantage that becomes unnecessary.

  FIG. 5 is a block diagram illustrating a configuration of transport control according to the second embodiment.

  In FIG. 5, the same components as those already described in FIG. 1 and the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 5, the conveyance information generation function unit of the controller 600 of this embodiment includes a correction unit 120 as a signal correction unit, a long period information generation unit 130 as a variation information generation unit, and a conveyance amount. A conveyance amount information calculation unit 140 ′ as information generation means. These functional units are realized as a part of a control program executed by the MPU 601 or a part of a logic circuit executed by the ASIC 603.

  An output signal of the rotary encoder 110 and an output signal of the laser Doppler velocimeter 111 are input to the transport information generation function, and transport amount correction information is output. The output conveyance amount correction information is input to the conveyance motor driver 642. The carry motor driver 642 controls the carry motor M2 based on the inputted carry amount correction information. Here, the conveyance amount correction information is information for correcting the rotation amount of the conveyance motor M2 rotated by the conveyance motor driver 642.

  Next, the generation of the conveyance amount error information will be described with reference to the drawings.

  FIG. 6 is a block diagram illustrating a functional configuration of the transport information generation function unit.

  In FIG. 6, the correction unit 120 and the long cycle information generation unit 130 have the same functions as those in the first embodiment, and thus description thereof is omitted. Of the functional blocks constituting the carry amount information calculation unit 140 ′, the roller rotation signal edge detection unit 141, the carry movement amount error value calculation unit 142, and the carry movement amount error integration unit 143 are the same as those in the first embodiment. .

  As described in the first embodiment, the transport movement amount error integration unit 143 outputs an integrated value of the transport movement amount error. In this embodiment, the transport movement amount error integrated value output from the transport movement amount error integration unit 143 is input to the roller rotation signal target correction value calculation unit 744.

  The roller rotation signal target correction value calculation unit 744 generates transport amount correction information for correcting the rotation amount of the transport motor M2 according to the input transport movement amount error integrated value. The conveyance amount correction information is output from the output terminal 104 and input to the conveyance motor driver 642. The transport motor driver 642 performs drive control of the transport motor M2 while correcting the rotation amount of the transport motor M2 based on the transport amount correction information.

  For example, if the outer circumference of the transport roller 14 is 50.8 mm and the output of the rotary encoder 110 is 10,000 pulses per revolution, the recording medium is ideally 50.8 mm / mm during the time between the rising edges of the output pulses. Move by 10000 = 5.08 μm. Therefore, for example, in order to convey the recording medium by 10.16 mm, the conveyance motor M2 is rotated by the amount corresponding to the encoder signal output corresponding to 2000 pulses.

  However, in reality, there is an error in the conveyance movement amount due to the eccentricity of the conveyance roller, etc., so the roller rotation signal target correction value calculation unit 744 calculates a correction value for the target pulse number of the rotary encoder. For example, when the conveyance movement amount error integrated value output from the conveyance movement amount error integration unit 143 is +178 μm, the conveyance amount correction information calculated by the roller rotation signal target correction value calculation unit 744 is − (178 / 2.54). ≒ -35 pulses.

  Therefore, in the conveyance motor driver 642 in which “−35 pulses” is input as the conveyance amount correction information from the roller rotation signal target correction value calculation unit 744, the target pulse number of the rotary encoder is changed to 2000−35 = 1965 pulses. Controls the amount of rotation of the roller. By doing so, it is possible to correct a conveyance amount error due to eccentricity of the conveyance roller.

  Therefore, according to the embodiment described above, the long period component of the speed fluctuation of the recording medium is extracted, the conveyance amount of the recording medium is calculated together with the rotation amount of the conveyance roller, and further, based on the information including the conveyance error. Controls motor drive. As a result, the influence of the eccentricity of the conveyance roller is reduced, and even when a defect occurs in the speed detection of the recording medium, the influence of the recording medium can be reduced and the conveyance amount of the recording medium can be controlled. It becomes possible.

  Although not described in detail because it is not the subject of the present invention, there are various transport speed profiles such as transporting a recording medium at a low speed immediately before stopping in order to improve the stopping accuracy of the recording medium. Are devised. The present invention can also be applied to such various speed profiles, and the intended effect can be obtained.

  Furthermore, when the resolution of the rotary encoder is not so high, the output pulse signal may be electrically divided by a processing circuit to generate a pseudo high resolution pulse signal. It is possible to apply and obtain the desired effect.

  FIG. 7 is a block diagram illustrating a configuration of transport control according to the third embodiment.

  In FIG. 7, the same components as those already described in FIG. 1 and Embodiments 1 and 2 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 7, in addition to the provision of the rotary encoder 110 (first roller rotation signal generating means) as in the first and second embodiments, the rotary encoder is also provided at one end of the discharge roller 20. 903 (second roller rotation signal generation means) is provided. The rotary encoder 903 includes an encoder wheel 901 and an encoder sensor 902.

  The output signal of the rotary encoder 110, the output signal of the rotary encoder 903, and the output signal of the laser Doppler velocimeter 111 are input to the conveyance information generation function unit of the controller 600. Furthermore, motor control information is input from the conveyance motor driver 642 to the conveyance information generation function unit.

  The conveyance information generation function unit according to this embodiment includes a recording medium movement signal correction unit (hereinafter, correction unit) 120 ′ as a signal correction unit, a long period information generation unit 130 as a variation information generation unit, and a conveyance amount information generation unit. The transport amount information calculation unit 140 ″. The transport information generation function unit outputs transport amount error information.

  Here, generation of transport amount error information will be described with reference to the drawings.

  FIG. 10 is a block diagram showing the configuration of the transport information generation function unit.

  In FIG. 10, a recording medium movement signal output from the laser Doppler velocimeter 111 is input from the first input terminal 101, and motor control information output from the transport motor driver 642 is input from the second input terminal 102. These are the same as in Examples 1 and 2. On the other hand, in this embodiment, the first roller rotation signal output from the rotary encoder 110 is input from the input terminal 103a, and the second roller rotation signal output from the rotary encoder 903 is input from the input terminal 103b. .

  In the functional blocks constituting the correction unit 120 ′, the cycle detection unit 121, the state determination unit 122, the state determination reference storage unit 123, the cycle correction unit 124, and the cycle correction value storage unit 125 are the same as those in the first embodiment.

  Further, the first roller phase detection unit 921 and the second roller phase detection unit 924 have the same functions as the roller phase detection unit 127 in the first embodiment. The first roller variation information storage control unit 922 and the second roller variation information storage control unit 925 have the same functions as the roller variation information storage control unit 128 in the first embodiment. The first roller variation information storage unit 923 and the second roller variation information storage unit 926 have the same functions as the roller variation information storage unit 129 in the first embodiment.

  In the recording medium movement signal correction information generation unit (hereinafter referred to as correction information generation unit) 126 ′, two pieces of first and second roller variation information output from the first and second roller variation information storage control units 922 and 925, respectively. One piece of information selected from is input. Further, the correction information generation unit 126 ′ receives the motor control information from the second input terminal 102, generates determination reference information and correction cycle information from these information, and each of them generates the state determination reference storage unit 123 and the cycle correction value. Store in the storage unit 125.

  Selection switching between the first roller fluctuation information and the second roller fluctuation information will be described later.

  In this way, the correction unit 120 ′ performs a correction process for dropout generated in the laser Doppler velocimeter 111, and outputs corrected pulse period information.

  The long cycle information generation unit 130 has the same function as that of the first embodiment and outputs movement amount variation rate information. The movement amount variation rate information output from the long cycle information generation unit 130 is input to the transport amount information calculation unit 140 ″.

  In the functional block constituting the long cycle information generation unit 140 ″, the first roller rotation signal edge detection unit 941 and the second roller rotation signal edge detection unit 944 have the same functions as the roller rotation signal edge detection unit 141 in the first embodiment. In addition, the first transport movement amount error value calculation unit 942 and the second transport movement amount error value calculation unit 945 have the same functions as the transport movement amount error value calculation unit 142 in the first embodiment. The first transfer movement amount error integration unit 943 and the second transfer movement amount error integration unit 946 have the same functions as the transfer movement amount error integration unit 143 in the first embodiment.

  Therefore, as described in the first embodiment, the first transport movement amount error integration unit 943 uses the recording medium movement signal that is the output of the laser Doppler velocimeter 111 and the first roller rotation signal that is the output of the rotary encoder 110. Thus, the first transport movement amount error integrated value is output. Further, from the second transport movement amount error integration unit 946, the second transport is similarly performed from the recording medium movement signal that is the output of the laser Doppler velocimeter 111 and the second roller rotation signal that is the output of the rotary encoder 903. The travel error integrated value is output.

  In the signal selection / synthesis unit 947, one of these two outputs is selected and output from the output terminal 104 as conveyance amount error information. When selection switching is performed during one transport of the recording medium, the signal selection combining unit 947 combines the integrated value of the transport movement amount error before switching and the integrated value of the transport movement amount error after switching. The calculated value is output as an integrated value of the transport movement amount error. Further, the selection switching between the first transport movement amount error integrated value and the second transport movement amount error integrated value is performed at the same timing as the selection switching between the first roller variation information and the second roller variation information described above.

  The transport amount error information generated in this way is output from the output terminal 104, input to the head driver 644, and used to determine the nozzle row drive range in the same manner as described in the first embodiment.

  Here, the selection switching timing in the correction information generation unit 126 ′ and the signal selection synthesis unit 947 will be described.

  In the recording apparatus shown in FIG. 1, when performing so-called borderless recording in which recording is performed on the entire surface of the recording medium P, when the recording medium is transported to perform recording on the rear end portion of the recording medium P, the recording medium P Passes through the position of the transport roller 14 and is transported only by the discharge roller 20.

  Normally, that is, when the recording medium P is carried by both the transport roller 14 and the discharge roller 20, the transport force of the transport roller 14 is generally set larger than the transport force of the discharge roller 20. Dominant. For this reason, the rotary encoder 110 provided at one end of the transport roller 14 is used for detecting the transport amount of the recording medium P.

  On the other hand, as described above, when the recording medium P is carried only by the discharge roller 20 and is transported only by the discharge roller 20, the rotary encoder 903 provided at one end of the discharge roller 20 is used to transport the recording medium P. Used for quantity detection.

  The timing at which the recording medium P passes the position of the conveyance roller 14 is determined from the conveyance movement amount after the leading edge of the recording medium P is detected and the size of the recording medium. In this embodiment, the transport amount of the recording medium is detected using the first roller rotation signal output from the rotary encoder 110 and the recording medium movement signal output from the laser Doppler velocimeter 111. Therefore, by integrating the transport movement amount, the timing at which the rear end portion of the recording medium P passes the position of the transport roller 14, that is, the selection switching timing in the correction information generation unit 126 ′ and the signal selection combining unit 947 is determined. Is done.

  Further, the surface linear velocity of the conveying roller 14 and the discharging roller 20 is generally set slightly higher for the discharging roller 20 than for the conveying roller 14. This is because tension is generated between the transport roller 14 and the discharge roller 20 to keep the distance between the nozzle forming surface of the recording head 3 and the recording medium P constant. Accordingly, when the rear end portion of the recording medium P passes through the position of the transport roller 14 and is transported only by the discharge roller 20, the transport is greater than when it is carried by both the transport roller 14 and the discharge roller 20. Slightly faster By utilizing this characteristic, it is possible to determine the selection switching timing in the correction information generation unit 126 ′ and the signal selection / synthesis unit 947 by measuring the fluctuation of the recording medium movement signal output from the laser Doppler velocimeter 111. It is.

  Furthermore, it is also possible to determine the selection switching timing in the correction information generation unit 126 ′ and the signal selection synthesis unit 947 by combining the above two methods.

  Therefore, according to the embodiment described above, a rotary encoder is provided for each of the transport roller and the discharge roller, each encoder signal is input, and one of the two encoder signals is selected according to the progress of the recording medium. Then, the conveyance control is performed according to the selected signal. As a result, for example, even when borderless recording is performed, the influence of eccentricity of the conveyance roller is reduced, and even when a defect occurs in the speed detection of the recording medium, the influence is reduced and the position control of the recording dots is performed. be able to. As a result, high quality image formation becomes possible.

  Furthermore, in order to directly measure the conveyance speed of the recording medium, in borderless recording, switching is performed when the recording medium P is carried only by the conveyance roller, by both the conveyance roller and the discharge roller, and only by the discharge roller. It is possible to cope with fluctuations in the conveyance speed of the recording medium that occur in This makes it possible to perform more accurate recording dot position control.

  Although the three embodiments to which the present invention can be applied have been described above, the present invention can also be applied to other examples described below.

  That is, as in the third embodiment, the transport roller and the discharge roller are each provided with a rotary encoder, and the transport movement amount of the recording medium is detected from them and the laser Doppler velocimeter, and based on the detected transport movement amount information, the second embodiment. As described above, the motor control is performed so as to reduce the conveyance amount error.

  In the first to third embodiments, the laser Doppler velocimeter is disposed at a position facing the recording head, but the present invention is not limited to this. For example, it may be located upstream of the position where the recording head is opposed, or may be located downstream of the transport. Further, in the case where the recording head is disposed at a position other than the position where the recording heads are opposed to each other, it is more preferable to arrange two or more laser Doppler velocimeters so that the moving speed can always be detected from the leading end to the trailing end of the recording medium. .

  Furthermore, the means for detecting the conveyance speed of the recording medium is not limited to the laser Doppler velocimeter. For example, a scale may be formed on the recording medium and detected optically, or may be detected optically without using a scattered light on the surface of the recording medium. Alternatively, the moving speed may be detected while performing image recognition with an area sensor.

  Furthermore, in order to extract the long period component of the recording medium movement signal, the average value of a plurality of period information is obtained in the above embodiment, but the present invention is not limited to this. For example, a low-pass filter having a more complicated configuration may be used, or a long-period component may be extracted by sampling at a desired period.

  In the above embodiments, the liquid droplets ejected from the recording head have been described as ink, and the liquid stored in the ink tank has been described as ink. However, the storage is limited to ink. It is not a thing. For example, a treatment liquid discharged to the recording medium may be accommodated in the ink tank in order to improve the fixability and water resistance of the recorded image or to improve the image quality.

  The above embodiment uses a method that includes means (for example, an electrothermal converter) for generating thermal energy for ink ejection, and causes a change in the state of the ink by the thermal energy, among ink jet recording methods. High density and high definition of recording can be achieved.

  In addition, as an embodiment of the ink jet recording apparatus of the present invention, in addition to those used as an image output apparatus of information processing equipment such as a computer, a copying apparatus combined with a reader or the like, and further a facsimile apparatus having a transmission / reception function. It may be one taken.

1 is an external perspective view showing an outline of a configuration of an ink jet recording apparatus that is a representative embodiment of the present invention. 3 is a block diagram illustrating a configuration of a control circuit of the recording apparatus. FIG. FIG. 3 is a block diagram illustrating a configuration of conveyance control according to the first embodiment. It is a block diagram which shows the function structure of the conveyance information generation function part according to Example 1. FIG. FIG. 10 is a block diagram illustrating a configuration of transport control according to a second embodiment. It is a block diagram which shows the function structure of the conveyance information generation function part according to Example 2. FIG. 10 is a block diagram illustrating a configuration of transport control according to a third embodiment. It is a block diagram which shows the function structure of the conveyance information generation function part according to Example 3. FIG. 6 is a diagram illustrating fluctuations in the conveyance speed of a recording medium. It is a figure which shows the principle of a laser Doppler velocimeter. It is a figure which shows the signal missing state of a laser Doppler velocimeter.

Explanation of symbols

M2 conveying motor 3 recording head 14 conveying roller 15 pinch roller 20 discharge roller 105 belt member 107 spur roller 108 encoder wheel 109 encoder sensor 110 rotary encoder 111 laser Doppler velocimeter 112 platen member 120 recording medium movement signal correction unit (correction unit)
121 Recording medium movement signal period detector (period detector)
122 Recording medium movement signal state determination unit (state determination unit)
123 Recording medium movement signal state determination reference storage unit (state determination reference storage unit)
124 recording medium movement signal cycle correction unit (cycle correction unit)
125 Recording medium movement signal cycle correction value storage unit (cycle correction value storage unit)
126 Recording medium movement signal correction information generation unit (correction information generation unit)
127 Roller Phase Detection Unit 128 Roller Fluctuation Information Storage Control Unit 129 Roller Fluctuation Information Storage Unit 130 Long Period Information Generation Unit 131 Recording Medium Movement Signal Period Average Value Calculation Unit (Period Average Value Calculation Unit)
132 Recording medium movement signal averaging section storage section (average section storage section)
133 Recording medium movement signal fluctuation information calculation section (variation information calculation section)
140 Transport amount information calculation unit 141 Roller rotation signal edge detection unit 142 Transport movement amount error value calculation unit 143 Transport movement amount error integration unit 642 Transport motor driver 644 Head driver 947 Signal selection synthesis unit

Claims (10)

A recording apparatus that performs recording on a recording medium by scanning a recording head having a row of recording elements composed of a plurality of recording elements,
A transport roller for transporting the recording medium;
A transport motor for generating a driving force of the transport roller;
Drive means for driving the transport motor;
A rotary encoder that is provided at one end of the transport roller and outputs a rotation signal indicating the position of the transport roller according to the rotation of the transport roller;
Detecting means for detecting the moving speed of the recording medium;
Correction means for correcting a movement signal representing the movement speed based on the rotation signal, the movement speed, and motor control information output from the driving means;
Generating means for generating long period fluctuation information about the moving speed based on the movement signal corrected by the correcting means and the motor control information;
A calculation unit that calculates a deviation amount of conveyance of the recording medium based on the long period variation information generated by the generation unit and the rotation signal;
Based on the transport deviation amount of the recording medium calculated by the calculating means, a recording element to be used for recording is determined from the plurality of recording elements, and recording is performed on the recording medium by the determined recording element. And a control means for controlling the recording apparatus.   The recording apparatus according to claim 1, further comprising a rotation signal correcting unit that corrects the rotation signal based on the conveyance deviation amount. A discharge roller for discharging the recording medium out of the recording apparatus;
Another rotary encoder provided at one end of the discharge roller and outputting a rotation signal indicating the position of the discharge roller according to the rotation of the discharge roller;
The correction means and the calculation means further input a rotation signal output from the separate rotary encoder,
Each of the correction unit and the calculation unit selects one of the two rotation signals from the two rotary encoders according to the progress of conveyance of the recording medium, and uses the selected rotation signal to move the movement The recording apparatus according to claim 1, wherein the recording apparatus corrects a signal and calculates a deviation amount of the conveyance.   4. The laser Doppler velocimeter that irradiates the recording medium with laser light and obtains the moving speed of the recording medium from the scattered light of the laser light. The recording device described in 1. The correction means includes
A period detecting means for detecting a period of a pulse signal output from the laser Doppler velocimeter;
Based on the rotation signal for each rotation of the transport roller or the discharge roller and the motor control information, information for determination to determine whether the cycle of the pulse signal is normal is generated, State determination means for determining whether the period of the pulse signal is within a reference range based on the determination information;
The recording apparatus according to claim 4, further comprising a period correction unit that corrects a period of the pulse signal based on a result of determination by the state determination unit. The generating means includes
Average value calculating means for obtaining an average value of the period of the pulse signal corrected by the period correcting means over a period longer than the output resolution of the laser Doppler velocimeter;
6. The recording according to claim 5, further comprising fluctuation information calculating means for generating fluctuation information of a long period for the moving speed based on the motor control information and an average value of the period of the pulse signal. apparatus. The calculating means includes
An edge detection means for detecting a rising edge of the rotation signal of the transport roller or the discharge roller;
An error value calculating means for calculating an error value of the moving amount of the recording medium per pulse of the rotation signal based on the fluctuation information;
Each time detection of the rising edge is input from the edge detection unit, the error value output from the error value calculation unit is integrated for a period in which the recording medium is conveyed once during a recording operation, and the conveyance is performed. The recording apparatus according to claim 6, further comprising an error value accumulating unit that calculates a deviation amount of the conveyance amount per operation.   When the conveyance roller and the discharge roller carry the recording medium, the correction unit and the calculation unit respectively select a rotation signal from a rotary encoder provided on the conveyance roller, and perform the discharge. 4. The recording apparatus according to claim 3, wherein when the recording medium is carried only by a roller, a rotation signal from a rotary encoder provided on the discharge roller is selected. A platen provided at a position facing the recording head;
The recording apparatus according to claim 4, wherein the laser Doppler velocimeter is provided at a position facing the recording head so that laser light passes through an opening of the platen. A recording apparatus that scans a recording head having a row of recording elements composed of a plurality of recording elements and performs recording on the recording medium while the recording medium is conveyed by a conveying roller using a driving force generated by a conveying motor. A recording control method,
Provided at one end of the transport roller, the rotation signal from the rotary encoder that detects the position of the transport roller according to the rotation of the transport roller, the moving speed of the recording medium detected by the detecting means, and the transport motor are driven. A correction step of correcting the movement signal representing the movement speed based on the motor control information output from the motor driver;
Based on the movement signal corrected in the correction step and the motor control information, a generation step for generating long period fluctuation information about the movement speed;
A calculation step of calculating a deviation amount of the conveyance of the recording medium based on the long period variation information generated in the generation step and the rotation signal;
A recording element to be used for recording is determined from the plurality of recording elements based on the deviation amount of the recording medium transport calculated in the calculating step, and recording is performed on the recording medium by the determined recording element. And a control process for controlling the recording.

Images