JP2009160944A - Recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize conveyance of a recording medium with high accuracy and at high speed by minimizing a conveyance error in a conveyance roller. <P>SOLUTION: A recording apparatus is provided with a first conveyance amount measuring means 1006 for obtaining the conveyance amount of the recording medium 1007 by measuring the rotation amount of the conveyance roller 1001 that conveys the recording medium 1007 and a second conveyance amount measuring means 701 for obtaining the conveyance amount of the recording medium 1007 by directly detecting the movement amount of the recording medium 1007 and controls the conveyance of the recording medium 1007 by using in combination of each of the output values obtained from the first conveyance amount measuring means 1006 and the second conveyance amount measuring means 701. Thereby the output value that can be obtained from the first conveyance amount measuring means 1006 can be corrected based on the output value obtainable from the second conveyance amount measuring means 701, and the output value for use in the conveyance control can be switched between both of them, as needed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a recording apparatus, and more particularly to a technique that enables a mechanism for feeding and conveying a recording medium to be driven at high speed and with high accuracy.

  In a recording apparatus in which an image is formed by a recording unit while transporting a recording medium inside the recording apparatus, various devices have been made in order to improve the transport accuracy of the recording medium (see, for example, Patent Document 1). Particularly in recent years, means for detecting the current position of the recording medium and controlling the conveyance speed using the detected contents has become a configuration necessary for forming an image at a target position on the recording medium (for example, Patent Document 2). Hereinafter, a recording medium conveyance control method which is generally applied will be described.

  FIG. 1 is a schematic diagram for explaining a main part of a transport system in a conventional recording apparatus. In the figure, reference numeral 1001 denotes a first transport roller, and reference numeral 1002 denotes a second transport roller. Reference numeral 1003 denotes a first pinch roller corresponding to the first conveying roller 1001, and reference numeral 1004 denotes a second pinch roller corresponding to the second conveying roller 1002. The conveyance rollers 1001 and 1002 play a role of conveying the recording medium 1007 in the direction of the arrow while sandwiching the recording medium 1007 between the pinch rollers 1003 and 1004. Reference numeral 1008 denotes a conveyance motor. The transport rollers 1001 and 1002 are rotated by engaging with the drive shaft of the transport motor 1008. In the recording medium 1007 to be conveyed, an image is recorded by the head cartridge 1 mounted on the carriage 2 in an area between the two conveying rollers 1001 and 1002.

  The rotation angle sensor 1006 and the code wheel 1005 are means for detecting the conveyance amount and conveyance speed of the recording medium. The code wheel 1005 is fixed on the same rotation axis as the first transport roller. Further, the code wheel 1005 has slits formed at equal intervals at the circumferential end thereof, and the rotation angle sensor 1006 fixedly installed in the recording apparatus can confirm the position of the slit. .

  FIG. 2 is an enlarged view showing how the rotation angle sensor 1006 detects the slit 201 of the code wheel 1005. The slits 201 are cut into the code wheel 1005 at equal intervals. The rotation angle sensor 1006 is an optical transmission sensor, detects the moving slit 201, and transmits a pulse signal at the detected timing. The rotation angle of the code wheel 1005 is detected from the transmitted pulse signal, and the position, velocity, and acceleration of the recording medium 1007 are calculated from the time interval at which the pulse signal is transmitted. Further, the rotation speed of the transport roller 1001 can be controlled using the obtained value.

  FIG. 3 is a diagram for explaining a control profile of a recording medium that is generally performed. In the figure, the horizontal axis represents elapsed time, the curve a represents the detected distance to the target position of the recording medium, and the curve b represents the speed at which the recording medium is conveyed. As shown in the figure, normally, when the position of the recording medium is far from the target position, the conveyance speed is accelerated for a certain period of time, then becomes a constant speed, and is decelerated when approaching the target position. Then, it is controlled to stop when it finally reaches the target position.

  In a general recording apparatus, transport control of a recording medium is performed by the method described above. When it is necessary to control the conveyance of the recording medium at a higher speed and with higher accuracy, conventionally, the accuracy of the mechanical dimension of the first conveyance roller that conveys the recording medium is improved, and the first Improvements have been made in technology for controlling the rotation angle of the conveying roller at a higher speed and with a higher accuracy.

JP 2002-128313 A JP 2002-137469 A

  However, in recent years, in order to record a higher quality image such as a photographic image quality, various configurations and precisions are required, such as recording finer-sized dots with higher density and higher definition. Under such circumstances, the accuracy of transporting the recording medium has to be dramatically improved, and there has been a limit to the mechanism and the control method as described above.

  For example, when the conveyance speed is extremely reduced, the output pulse from the rotation angle sensor 1006 becomes discrete, and there is a problem that it is very difficult to control the speed. Specifically, the mechanical friction load and the like change due to the decrease in speed, and the pulse signal acquired to grasp the actual speed becomes discrete including errors. The speed control is also likely to be unstable. In order to avoid this problem, there is a method of increasing the resolution of the slit 201 of the code wheel 1005, but there is actually a limit in manufacturing the code wheel. Nevertheless, in order to increase the resolution, there is a method of increasing the number of slits by increasing the diameter of the code wheel, that is, the circumference, but this method has caused an increase in the size of the apparatus itself.

  Further, the code wheel 1005 and the conveying roller 1001 have a large problem of eccentricity at the time of attachment, and this problem cannot be ignored as the control is precisely performed.

  There is also a problem with the stop position accuracy. When the recording medium is stopped with an accuracy equal to or higher than the resolution of the code wheel 1005, the recording medium is stopped by prediction while the true position cannot be grasped between the slits. In this case, there is a fear that the stop position may fluctuate due to mechanical friction load fluctuations or the like against prediction.

  Furthermore, the transport amount obtained by the conventional method is an indirect calculation value determined from the rotation angle of the code wheel 1005, and cannot be obtained by directly measuring the transport amount of the recording medium 8. Absent. Therefore, there is a problem that a dimensional error and an attachment error of parts arranged downstream from the code wheel 1005, a slip amount due to a friction difference between the recording medium 1007 and the pinch roller, and the like all become errors in the transport distance. It was.

  When the conventional recording medium control method having the problems as described above is applied, some adverse effects which are concerned in the environment surrounding the recent recording apparatus will be specifically described.

  1) Diversification of recording media and conveyed items such as plain paper, coated paper, glossy paper, and plastic trays for CD-R printing has been progressing. Therefore, the characteristics such as the friction coefficient of the surface of the recording medium and the conveyed product are diversified, and the magnitude of the frictional force generated between the conveyed product and the conveying roller is also varied. Therefore, even for the same rotation angle of the transport roller, the actual transport amount differs depending on the type of the transport object, and there is a problem that an accurate transport amount cannot be obtained even if only the rotation angle of the transport roller is controlled. It was.

  2) There is slight eccentricity and vibration in the gear that drives the transport system and the encoder that is used for control. Therefore, in terms of control, even if the sensor is used to control to the correct rotation angle, the actual transport amount includes some errors in the mechanical system. In the high-definition conveyance accuracy required in recent years, this error has become a size that cannot be ignored.

  3) In the conventional configuration in which the recording medium feed amount is converted from the rotation angle sensor, in order to further increase the resolution of the detectable rotation angle, there is a method of increasing the diameter of the wheel serving as the scale of the rotation angle sensor. is there. However, in this case, since the size of the wheel directly affects the size of the recording device, the size of the wheel is limited in the situation where importance is given to downsizing of the device as in recent years. Therefore, there is a limit in improving the resolution of the rotation angle, that is, the conveyance accuracy.

  4) In recent years, there is a high demand for so-called “borderless recording” in which recording is performed up to the end of the recording medium. When performing such recording, there occurs a situation in which the recording medium leaves the first transport roller and is transported only by the second transport roller at the stage of recording the last end of the recording medium. A slight error is inevitably generated in the transport performance between the first transport roller and the second transport roller due to the difference in the mechanical transmission path. When recording the rear end portion, there is a problem that this error causes a shift in the recording position and causes a significant image defect. In recent “borderless recording”, as a countermeasure, a method of suppressing a mechanical error by reducing the amount of conveyance of a recording medium at one time is employed. However, this method has a new problem that the recording speed is lowered.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to reduce conveyance errors caused by the conveyance rollers as much as possible and realize conveyance of a recording medium with high accuracy and high speed. It is.

Therefore, according to the present invention, in a recording apparatus that records on a recording medium to be conveyed, the first roller and the second roller and the first roller that are arranged apart from each other in the direction in which the recording medium is conveyed are rotated. A first unit that has a motor for driving, and that obtains a conveyance amount of the recording medium by measuring a rotation amount of the first roller using a conveyance unit that conveys the recording medium and a rotation angle sensor; A transport amount measuring unit; a second transport amount measuring unit that acquires a transport amount of the recording medium by performing image processing on a plurality of pieces of image data detected at different timings using a line sensor or an area sensor; Control means for performing drive control of the motor by using respective output values obtained from the transport amount measuring means and the second transport amount measuring means And a position where recording is performed on the recording medium and a position detected by the line sensor or area sensor are both positioned in a region between the first roller and the second roller in the direction in which the recording medium is conveyed. It is characterized by doing.

  According to the present invention, the output value obtained from the first transport amount measuring means is corrected by the output value obtained from the second transport amount measuring means, and the output values used for the transport control are both set as necessary. Or switch between them. As a result, the recording medium can be conveyed at high speed and with high accuracy.

FIG. 10 is a schematic diagram for explaining a main part of a conveyance system in a conventional recording apparatus. It is an enlarged view for demonstrating the state of a rotation angle sensor and a code wheel. It is a figure for demonstrating the control profile of the recording medium generally performed. It is a figure which shows the structure of the principal part in the inkjet recording device to which this invention is applied. FIG. 4 is a schematic perspective view for partially showing a main part structure of a recording head part of a head cartridge applicable in the embodiment. It is a block diagram for demonstrating the structure of control in the inkjet recording device applied by embodiment of this invention. It is a schematic diagram for demonstrating the main structures of the conveyance system most characteristic of this invention. It is an enlarged view for demonstrating the structural example of a movement distance reading sensor. 6 is a flowchart of processing performed by a CPU in transport control of a recording medium in Embodiment 1 of the present invention. FIG. 6 is a diagram for explaining a recording medium conveyance state at each timing. It is a schematic diagram for demonstrating another example of the main structures of the conveyance system most characteristic of this invention.

  In this specification, “record” means not only when forming significant information such as characters and figures but also whether it is manifested so that it can be perceived visually by humans, regardless of significance or insignificance. Regardless of the case, an image, a pattern, a pattern, or the like is widely formed on the recording medium, or the medium is processed.

  Here, the “recording medium” (hereinafter also referred to as a sheet material) refers not only to paper used in a general recording apparatus but also to a material that can accept ink, such as cloth, plastic film, and metal plate. Shall.

  Further, the term “ink” should be interpreted broadly in the same way as the definition of “recording”. When applied to a recording medium, it is used for forming an image, pattern, pattern, etc. or processing the recording medium. Say liquid to get.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the element shown with the same code | symbol shall respectively show the same or corresponding element.

FIG. 4 shows the configuration of the main part of an ink jet recording apparatus applicable to the present invention.
In FIG. 4, the head cartridge 1 is detachably mounted on the carriage 2. The head cartridge 1 has a recording head portion provided with a plurality of recording elements for ejecting ink, for example, as droplets, and an ink tank portion for replenishing each recording element with ink.

  Further, the head cartridge 1 is provided with a connector for transmitting and receiving a signal for driving the recording head portion, and the carriage 2 has a connector holder for transmitting a drive signal and the like to the head cartridge 1 via the connector. Is provided.

  Reference numeral 3 denotes a guide shaft installed in the apparatus main body. The carriage 2 is guided and supported by a guide shaft 3 and can reciprocate in the main scanning direction in the figure along the direction in which the guide shaft 3 extends. The carriage 2 is moved by the main scanning motor 4 through a driving mechanism such as a motor pulley 5, a driven pulley 6, and a timing belt 7, and its position and moving amount are controlled.

  Further, the carriage 2 is provided with a home position sensor 30. When the home position sensor 30 passes over the shielding plate 36 at the home position, it can be detected that the carriage 2 is at the home position.

  Before recording is performed, the sheet material 8 such as a recording medium or a plastic thin plate is stacked on the auto sheet feeder 32. When recording is started, the paper feed motor 35 is driven, and this driving force is transmitted to the pickup roller 31 via a gear. As a result, the pickup roller 31 rotates, and the sheet material 8 is separated from the auto sheet feeder 32 one by one and fed into the recording apparatus.

  Subsequently, the sheet material 8 is conveyed in the sub-scanning direction at a predetermined speed by the rotation of the conveying roller 9 and passes through a position facing the ejection port surface of the head cartridge 1. The rotation of the conveyance roller 9 is achieved by transmitting the rotation of the conveyance motor 1008 via a gear. Although not shown in the drawing, apart from the first transport roller 9, a second transport roller is provided further downstream from the carriage. And this 2nd conveyance roller also rotates with the 1st conveyance roller, and has the composition which conveys sheet material 8.

  The head cartridge 1 mounted on the carriage 2 is held so that its discharge port surface protrudes downward from the carriage 2 and is parallel to the sheet material 8 between the two pairs of transport rollers described above. Further, the back surface of the sheet material 8 is supported by a platen (not shown) so as to form a flat recording surface in the recording portion. When the sheet material 8 passes through the lower part, the head cartridge 1 ejects ink to the sheet material 8 according to a predetermined image signal.

  33 is a paper end sensor capable of confirming the presence or absence of the sheet material 8. When the sheet material 8 is fed, it is possible to determine whether or not the sheet material 8 has been fed normally by detection of the paper end sensor 33. The timing at which the paper end sensor 33 detects the leading end of the sheet material 8 is also used to determine the recording start position of the fed sheet material 8. Further, in the final stage of recording, by detecting the rear end portion of the sheet material 8, the position of the rear end portion in the subsequent recording is grasped, and the position on the sheet material currently being recorded is determined. Also, the paper end sensor 33 is used.

  The head cartridge 1 applied in the present embodiment is an inkjet head cartridge that ejects ink using thermal energy, and includes a plurality of electrothermal transducers for generating thermal energy. Specifically, thermal energy is generated by a pulse signal applied to the electrothermal transducer, and film boiling occurs inside the ink liquid by this thermal energy. Further, the ink is discharged from the ejection port using the foaming pressure of film boiling. Recording is performed by discharging.

  FIG. 5 is a schematic perspective view for partially showing the main structure of the recording head portion 26 of the head cartridge 1 applicable in the present embodiment.

  In FIG. 5, a plurality of discharge ports 22 are formed at a predetermined pitch on the discharge port surface 21 facing the sheet material 8 at a predetermined interval (for example, about 0.5 to 2.0 mm). The discharge ports 22 are formed with liquid passages 24 communicating with the common liquid chambers 23, respectively, and the capillary force forces the ink present in the common liquid chambers to the respective discharge ports. On each wall surface of the liquid passage 24, an electrothermal converter (such as a heating resistor) 25 for generating heat energy is disposed. A predetermined pulse is applied to the electrothermal transducer 25 based on the image signal or the ejection signal, and the heat generated thereby causes film boiling in the ink in the liquid path 24. A predetermined amount of ink is ejected as droplets from the ejection port 22 by the foaming pressure at this time.

  In the present embodiment, a serial type ink jet recording apparatus is applied, and the ejection ports 22 of the head cartridge 1 are arranged in a direction crossing the scanning direction of the carriage 2. Then, by repeating the recording main scan for ejecting ink from each ejection port 22 while moving and scanning the carriage 2 and the sub-scan for conveying a predetermined amount of the recording medium (sheet material) in a direction intersecting the recording medium (sheet material), An image is sequentially formed on a recording medium. However, applying the serial type recording apparatus does not limit the present invention.

FIG. 6 is a block diagram for explaining a control configuration in the ink jet recording apparatus applied in the present embodiment.
In FIG. 6, a controller 100 is a main control unit of the recording apparatus. For example, a CPU 101 in the form of a microcomputer, a ROM 103 storing programs, necessary tables and other fixed data, an area for developing image data, a work area, and the like. The RAM 105 is provided.

  The host apparatus 110 is an apparatus connected to the outside of the recording apparatus and serving as an image supply source. The host device 110 may be a computer that creates and processes data such as images related to recording, or may be in the form of a reader unit for image reading. Image data, other commands, status signals, and the like supplied from the host device 110 can be transmitted to and received from the controller 100 via an interface (I / F) 112.

  The operation unit 120 is a switch group that receives an input instruction from an operator, and includes a power switch 122, a recovery switch 126 for instructing activation of suction recovery, and the like.

  The sensor unit 130 is a sensor group for detecting the state of the apparatus. In the present embodiment, in addition to the home position sensor 30 and the paper end sensor 33 described above, a temperature sensor 134 and a rotation angle sensor 1006 provided for detecting the environmental temperature, and a movement distance reading sensor 701 unique to the present invention. Etc.

  A head driver 140 drives the electrothermal transducer 25 of the recording head 26 in accordance with the recording data. The head driver 140 also includes a shift register that aligns recording data in correspondence with each of the plurality of electrothermal transducers 25, a latch circuit that latches at appropriate timing, and the electrothermal transducer 25 in synchronization with a drive timing signal. A logic circuit element to be operated, and a timing setting unit for appropriately setting the ejection timing in order to adjust the dot formation position on the recording medium are included.

  A sub heater 142 is provided in the vicinity of the recording head 26. The sub-heater 142 adjusts the temperature of the recording head in order to stabilize the ink ejection characteristics, and may be formed on the substrate of the recording head 26 in the same manner as the electrothermal transducer 25. 26 may be attached to the main body or the head cartridge 1.

  150 is a motor driver for driving the main scanning motor 4, and 170 is a motor driver for driving the transport motor 1008. The carriage 2 can be moved in the main scanning direction by driving the main scanning motor 4, and the sheet material 8 is conveyed in the sub scanning direction by driving the conveyance motor 1008.

  Reference numeral 160 denotes a motor driver for driving the paper feed motor 35, and the sheet material 8 is separated from the auto foot seeder 32 by the drive of the paper feed motor 35 and fed into the recording apparatus.

  FIG. 7 is a schematic diagram for explaining the main configuration of the most characteristic transport system of the present invention, in comparison with FIG. 1 described in the background section.

In this embodiment, a movement distance reading sensor 701 capable of directly reading the movement distance of the recording medium 1007 downstream of the first conveying roller 1001 with respect to the conventional recording apparatus described in FIG. Is installed. The effect of the present invention can be obtained by installing the movement distance reading sensor 701 between the two rollers. In the present embodiment, the movement distance reading sensor 701 is used as a carriage near the ejection port surface of the head cartridge 1. 2 is arranged on the side surface. As another embodiment, as shown in FIG. 11, the moving distance reading sensor 701 may be arranged at a position facing the discharge port surface of the head cartridge 1 and detected from the back side of the recording medium.

  FIG. 8 is an enlarged view for explaining a configuration example of the movement distance reading sensor 701. In the figure, the movement distance reading sensor 701 is provided with an LED 61 and a light receiving portion 62 as light sources as shown in the figure. As the light receiving unit 62, a line sensor in which light receiving elements are arranged one-dimensionally or an area sensor in which two-dimensional arrangement is arranged can be used. The light receiving element may be a CCD or CMOS.

  As an operation principle, the LED 61 emits light to the moving recording medium 1007, and the light receiving unit 62 takes in the reflected light at regular time intervals. Then, the data captured at each timing is subjected to image processing, and the feature is extracted, whereby the distance at which each image deviates from the previous event can be acquired.

  Various methods can be applied to image feature extraction. For example, a method of performing a Fourier transform to check the match for each frequency may be employed, or a method of extracting only a peak portion and acquiring a shift amount of the position may be employed. Furthermore, a method of binarizing the acquired image and matching the binarized pattern is also common. Whichever method is adopted, it is possible to obtain an instantaneous value of the speed from the obtained movement distance per unit time and to calculate an acceleration value from the change in the speed before and after.

  The use of such a reflective optical sensor can measure the speed and the amount of movement every unit time, and this point is greatly different from the case where the rotation angle sensor is used. Since the rotation angle sensor measures time per unit distance, high-precision control is difficult during low-speed operation, but according to this embodiment, the recording medium can be conveyed with stable accuracy regardless of the conveyance speed. It is possible to acquire the speed.

  Hereinafter, some examples will be described in order to explain the effects to be verified using the recording apparatus of the present embodiment to which the movement distance reading sensor 701 is applied.

Example 1
FIG. 9 and FIG. 10 are diagrams for explaining a flowchart of processing performed by the CPU 101 and a recording medium conveyance state at each timing in the recording medium conveyance control in this embodiment.

  Referring to both figures, when recording is started, first, feeding of the recording medium 1007 is started in STEP1. The recording medium 1007 is carried in the direction of the arrow as shown in FIG.

  In STEP 2, it is determined whether or not the paper end sensor 33 has detected the leading end of the recording medium 1007, and the feeding operation in STEP 1 is continued until the detection is confirmed.

  When the leading edge of the recording medium 1007 is confirmed in STEP 2, the process proceeds to STEP 3, and the conveyance speed and position control by the rotation angle sensor 1006 is started from this position. This stage corresponds to FIG.

  In STEP 4, it is determined whether or not the movement distance reading sensor 701 has confirmed the presence of the recording medium 1007. Until it is confirmed, the conveyance speed and position are controlled by the rotation angle sensor 1006 in STEP3.

  If it is confirmed in STEP4 that the recording medium 1007 is present by the movement distance reading sensor 701, that is, if it is in the state of FIG. 10C, the process proceeds to STEP5.

  In STEP5, the detection of the conveyance speed by the movement distance reading sensor 701 is started, and at the same time, the rotation of the conveyance roller 1001 and the actual conveyance are determined from the difference between the value detected by the rotation angle sensor 1006 and the value detected by the movement distance reading sensor 701. An error generated between the recording medium 1007 and the amount is calculated and stored in a memory in the recording apparatus main body in a state where the type of the recording medium 1007 can be identified. In detecting this error, for example, when the cause of the error is mainly the eccentricity of the conveyance roller, it is preferable to continue the error detection at a distance equal to or greater than the circumference of the conveyance roller during one rotation of the conveyance roller. Of course, an error value may be acquired and stored in the entire area that can be simultaneously detected by the rotation angle sensor 1006 and the movement distance reading sensor 701. In STEP 6, the conveyance control by the rotation angle sensor 1006 is continued.

  When the conveyance proceeds to the position of FIG. 10D and the paper end sensor 33 confirms the rear end portion of the recording medium 1007 in STEP 7, the rear end portion of the recording medium 1007 is detected by the movement distance reading sensor 701 in STEP 8. The position immediately before the position is calculated.

  Then, the conveyance of the recording medium 1007 is continued until the calculated value obtained in STEP 9 is reached. When the recording is completed, the recording medium 1007 is discharged by STEP 10 and the present process is terminated.

  In this embodiment, for each type of recording medium, an error in the conveyance amount by the conveyance roller 1001 is stored in the memory. Therefore, the next time recording is performed on the same type of recording medium, the previously stored error information can be used. Specifically, in the region where the rotation control is performed by the rotation angle sensor, by recognizing the conveyance amount that is larger (or smaller) by a predetermined amount in a predetermined direction than the conveyance amount detected by the rotation angle sensor, The actual transport amount can be corrected to a target value. In this way, it is possible to perform suitable recording on a recording medium having any friction coefficient while reducing the transport error as much as possible.

(Example 2)
In the present embodiment, the method for correcting the transport amount according to the type of the recording medium described in the first embodiment is performed, and the transport position of the recording medium is determined with an accuracy equal to or higher than the resolution of the rotation angle sensor 1006 to perform recording. A method for stopping the medium will be described.

  The resolution of the moving distance reading sensor 701 applied in this embodiment is assumed to be higher than the resolution of the rotation angle sensor 1006. Therefore, without increasing the diameter of the code wheel 1005 used for the rotation angle sensor 1006, it is possible to set the conveyance resolution and thus the recording resolution high while keeping the recording apparatus small.

  The actual operation will be described. When the carry amount is larger than a predetermined value, the carry control is first performed by the rotation angle sensor 1006 up to a value close to the target carry amount and smaller than this. At this time, the error between the output of the rotation angle sensor 1006 and the actual conveyance distance of the recording medium 1007 may be corrected by using the correction value stored by adopting the method shown in the first embodiment. it can. However, adopting this method does not limit the present embodiment.

  After carrying the necessary distance under the control of the rotation angle sensor 1006, in this embodiment, the carrying control is switched to the movement distance reading sensor 701. The remaining small distance is transported by the recording medium 701 under the control of the moving distance reading sensor 701 with higher resolution.

(Example 3)
In the present embodiment, the method for correcting the conveyance amount according to the type of the recording medium described in the first embodiment is performed, and the control method for performing a low-speed operation that is difficult to control with the resolution of the rotation angle sensor 1006 is described. To do.

  In the rotation angle sensor 1006 that outputs a pulse at the timing when the transport roller 1001 rotates by a predetermined pitch, when the transport speed, that is, the rotational speed of the roller fluctuates, the intervals of generated pulses are discrete. Even in such a case, if a certain rotational speed is maintained, the algorithm for controlling the speed can be controlled relatively well, but immediately before the stop at the finally determined position. The rotation speed is also considerably reduced, and the control tends to be very unstable.

  Here, this phenomenon will be described in more detail. Immediately before attempting to stop at the finally determined position, the deviation of the position information of the recording medium is reduced, and the speed command value is also reduced. Therefore, the power actually input to the transport motor 1008 is considerably reduced. In this case, if the motor torque is insufficient due to individual variations in motor torque or variations in the friction of individual mechanical systems, the conveyance speed is abnormally reduced. And on control, the action which raises electric power and raises torque arises. However, if the transport speed is very low, speed information can be acquired only discretely, so in order to judge whether the speed is actually increasing, a very gentle rate of increase Must be set to prevent the control system from oscillating. Therefore, there is a problem that the time required for positioning and stopping becomes extremely long especially after entering the low speed control region.

  In this embodiment, when the conveyance speed of the recording medium 1007 becomes lower than a predetermined value, the conveyance control is performed using the rotation angle sensor 1006 and the movement distance reading optical sensor 701 together. . As a result, in the low speed region, information having higher resolution than that of the rotation angle sensor 1006 can be obtained from the movement distance reading optical sensor 701. Therefore, the control can be performed at the same level as the speed other than the low speed, and the above-described problems are solved. It is.

  In this embodiment, at the top speed of conveyance, by applying a rotation angle sensor that does not decrease the sampling frequency even during high-speed conveyance, even if it is impossible to sample in response speed, it is stable. Sampling can be ensured. On the other hand, in the low speed control state, by using the movement distance reading optical sensor 701, the characteristic that sampling can always be performed at a constant frequency is utilized. By adopting such a configuration, the deviation from the target position can be made extremely small, so that the necessary motor torque control can be properly performed even in the low speed control state. It is possible to stop at the target position in a short time.

  The timing at which control is transferred from the rotation angle sensor to the movement distance reading sensor may be applied when the conveyance speed falls below a predetermined value. Control by the movement distance reading sensor may be performed in the entire area.

  As another setting method, a configuration may be used in which only the speed control uses the detection value of the movement distance reading sensor. If the rotation angle sensor is sufficient for the positioning accuracy itself, the moving distance reading sensor may be used by taking advantage of the advantage that the position can be determined at a higher speed by using only the effectiveness in the speed control described above. .

  Also in the present embodiment, the error between the output of the rotation angle sensor 1006 and the actual conveyance distance of the recording medium 1007 is corrected by using the correction value stored by adopting the method shown in the first embodiment. You can also However, adopting this method does not limit the present embodiment.

Example 4
This embodiment can be carried out independently or simultaneously with the methods of the first to third embodiments described above, and the rear end of the recording medium leaves the first conveying roller, and the second conveying roller. This is a method used in a situation where recording is performed while transporting a recording medium only.

  Also in this embodiment, the conveyance control of the recording medium 1007 is switched from the rotation angle sensor 1006 to the movement distance reading sensor 701 at a predetermined timing. The timing for switching the control is generally “just before the recording medium is removed from the first conveyance roller after the paper end sensor 33 detects the trailing edge of the recording medium 1007 and a certain amount of conveyance is performed”. It is preferable. However, switching at this timing does not limit the present embodiment and the present invention.

  Since the first transport roller and the second transport roller have different component parts, some error is inevitably caused in the transport accuracy between the two. Therefore, in a situation where the rear end of the recording medium 1007 passes through the first pinch roller 1003 and is transported only by the second transport roller, the transport accuracy is higher than the state transported by both transport rollers. Are also prone to instability.

  In such a situation, in this embodiment, even when transporting only with the second transport roller, the transport control is performed based on the movement distance reading sensor with higher accuracy, thereby reducing the accuracy to the rear end. This ensures reliable transport without any problems. After recording to the extreme end of the rear end, as in “Borderless recording”, the control is switched to the rotation angle sensor again and the second transport roller is rotated, so that a quick paper discharge operation can be performed. Can be done.

  The present invention can be used in a recording apparatus that records an image on a recording medium while conveying the recording medium.

DESCRIPTION OF SYMBOLS 1 Head cartridge 2 Carriage 3 Guide shaft 4 Main scanning motor 5 Motor pulley 6 Driven pulley 7 Timing belt 8 Sheet material 8
DESCRIPTION OF SYMBOLS 9 Conveyance roller 21 Discharge port surface 22 Discharge port 23 Common liquid chamber 24 Liquid path 25 Electrothermal conversion body 26 Recording head part 30 Home position sensor 31 Pickup roller 32 Auto sheet feeder 33 Paper end sensor 35 Paper feed motor 36 Shielding plate 61 Light source 62 Light Receiving Element 100 Controller 101 CPU
103 ROM
105 RAM
110 Host device 112 Interface 120 Operation unit 122 Power switch 122
126 Recovery switch 130 Sensor unit 134 Temperature sensor 140 Head driver 142 Sub heater 150, 160, 170 Motor driver 201 Slit 701 Movement distance reading sensor 1001 First transport roller 1002 Second transport roller 1003 First pinch roller 1004 Second Pinch roller 1005 Code wheel 1006 Rotation angle sensor 1007 Recording medium 1008 Conveyance motor

Claims (4)

In a recording apparatus for recording on a transported recording medium,
A first roller and a second roller disposed apart from each other in a direction in which the recording medium is conveyed, and a motor for rotating the first roller, and conveying means for conveying the recording medium;
  First conveyance amount measuring means for obtaining the conveyance amount of the recording medium by measuring the rotation amount of the first roller using a rotation angle sensor;
  A second transport amount measuring means for acquiring a transport amount of the recording medium by performing image processing on a plurality of image data detected at different timings using a line sensor or an area sensor;
  Control means for performing drive control of the motor by using respective output values obtained from the first carry amount measuring means and the second carry amount measuring means;
Comprising
  Both the recording position on the recording medium and the detection position by the line sensor or area sensor are located in a region between the first roller and the second roller in the direction in which the recording medium is conveyed. A recording apparatus.   The second roller is installed on the downstream side of the first roller in the direction in which the recording medium is conveyed when recording is performed, and the first roller is rotated by the driving of the motor. The recording apparatus according to claim 1, wherein the second roller rotates as the roller rotates. The line sensor or area sensor is mounted on a carriage mounted with an ink jet recording head and moves in a direction crossing the direction in which the recording medium is transported, and performs detection from the surface side on which recording is performed on the recording medium. The recording apparatus according to claim 1, wherein: The line sensor or the area sensor is disposed on a side facing the ink jet recording head with the recording medium interposed therebetween, and detects from the back side of the surface on which recording is performed on the recording medium. 2. The recording apparatus according to 2.

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