1. Field of the Invention
The present invention relates to a recording apparatus.
2. Description of the Related Art
Japanese Patent Application Laid-Open No. 2007-301768 discusses that, to perform recording on a recording medium that is being conveyed, drive timing of a recording head is adjusted corresponding to an angular velocity of a driving roll. Further, it discusses that eccentricity data is previously stored in a memory, a reference clock signal is set delayed based on a delay time corresponding to an amount of the eccentricity of a roll and a delay time corresponding to the angular velocity, and then a print clock is output. Furthermore, it discusses that a print timing signal is output based on the print clock.
Even without considering influence of the eccentricity of the roll, a rotational velocity of the driving roll included in a conveyance unit may not correspond to a conveyance speed of a recording medium. The driving roll is rotated by driving a motor, which is a drive source of the driving roll, at a predetermined speed. In this conveyance configuration, an error can be caused between the assumed conveyance speed of the recording medium and the actual conveyance speed thereof. The error depends on conditions (type and size of the recording medium, environment temperature, and environment moisture) when a recording apparatus performs a recording operation. For example, a cause of the error can be a diameter of the roller that varies depending on the environment temperature, pressing force of a pinch roller that varies depending on a size of the recording medium to be conveyed, and a friction force between the recording medium and the roller depending on a type of the recording medium.
Thus, it is demanded that the number of lines to be recorded on the recording medium is adjusted corresponding to a rotation amount of the driving roll to perform the recording. According to Japanese Patent Application Laid-Open No. 2007-301768, correction of the eccentricity of the roll can be controlled but adjustment of the number of lines to be recorded on the recording medium cannot be controlled.
According to an aspect of the present invention, a recording apparatus includes a recording head, a roller configured to convey a recording medium, an acquisition unit configured to acquire information about a conveyance amount for conveying the recording medium per a predetermined rotation amount of the roller, a recording timing generation unit configured to generate a plurality of timing signals for performing recording for one raster line according to a rotation of the roller during one rotation thereof, and a drive signal generation unit configured to generate a drive reference signal for performing the recording for the one raster line on the recording medium at a predetermined interval based on the conveyance amount information and the timing signal.
Further features and aspects of the present invention will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the invention and, together with the description, serve to explain the principles of the invention.
Various exemplary embodiments, features, and aspects of the invention will be described in detail below with reference to the drawings.
A printer (recording apparatus) performs recording on a continuous sheet wound in a roll shape.
The sheet supply unit 1 stores and supplies the continuous sheet wound in a roll shape. The sheet supply unit 1 can store two rolls R1 and R2, and alternatively draws and supplies the sheet. The number rolls that can be stored is not limited to two, and any number of rolls greater than or equal to one roll can be stored.
The de-curl unit 2 reduces curl (warpage) of the sheet supplied from the sheet supply unit 1. By using two pinch rollers for one driving roller, the de-curl unit 2 strokes the sheet to give the warpage in an opposite direction of the curl to reduce the curl.
The skew correction unit 3 corrects skew (inclination against an original traveling direction) of the sheet that has passed the de-curl unit 2. The skew of the sheet is corrected by pressing an edge of the sheet at a reference side to a guide member.
The print unit 4 forms an image on the sheet that is being conveyed by using the recording head 14. The print unit 4 also includes a plurality of conveyance rollers (conveyance members) that convey the sheet.
The recording head 14 includes the recording head of a line type on which a nozzle array of an inkjet method is formed within a range for covering the maximum width of the sheet that is assumed to be used. The recording head 14 includes a plurality of the recording heads disposed in parallel in a conveyance direction. According to the present exemplary embodiment, seven recording heads corresponding to seven colors of cyan (C) ( ) magenta (M), yellow (Y), light cyan (LC), light magenta (LM), gray (G), and black (K) are included. Furthermore, the number of colors and the number of recording heads are not limited to seven.
An inkjet method can adopt a method using an electrothermal conversion device, a method using a piezoelectric element, a method using an electrostatic element, and a method using a micro electromechanical system (MEMS) element, as a recording element. Each color ink is supplied to the recording head 14 from an ink tank through an ink tube.
The test unit 5 optically reads a test pattern and the image printed on the sheet by the print unit 4, to test a state of the nozzles of the recording heads, a state of conveying the sheet, and an image position.
The cutter unit 6 includes a mechanical cutter for cutting a printed sheet by a predetermined length. The cutter unit 6 includes a plurality of conveyance rollers for sending the sheet to a next processing. The information recording unit 7 records print information including a serial number and date of printing on a rear surface of the cut sheet. The drying unit 8 heats up the sheet printed by the print unit 4 and dries applied ink in a short time. The drying unit 8 includes conveyance belts and conveyance rollers for sending the sheet to the next processing.
The sheet winding unit 9 temporarily wind the continuous sheet on which front-surface printing has been finished when two-sided printing is performed. The sheet winding unit 9 includes a winding drum that rotates to wind the sheet. The winding drum temporarily winds the continuous sheet on which the front-surface printing has been finished and has not been cut yet. When winding is finished, the winding drum rotates in reverse to supply the wound sheet to the de-curl unit 2, and then sent it to the print unit 4. Since the sheet is reversed inside out, the print unit 4 can perform printing on the rear surface. More specific operation of the two-sided printing will be described below.
The discharge and conveyance unit 10 conveys the sheet cut by the cutter unit 6 and dried by the drying unit 8, and sends the sheet to the sorter unit 11. The sorter unit 11 separates as necessary the sheets on which the printing has been finished, to discharge them to different trays of the discharge tray 12 for each group.
The control unit 13 controls an overall printer. The control unit 13 includes a central processing unit (CPU) 100, a memory retaining a control program, a controller 15, and an interface unit. The control unit 13 communicates with an external device 16 via an interface.
A drive source of the main conveyance roller 17 is a stepping motor 61. A motor control unit 60 included in the control unit 13 open-controls drive of the stepping motor 61 according to a predetermined speed table. The speed measuring unit 25 measures, for example, an average speed of the recording medium in a predetermined period (time period when the main conveyance roller 17 is rotated a plurality of times). This average speed is used to perform the control as the conveyance speed of the recording medium.
In addition, the speed measuring unit 25 measures a moving amount of the recording medium (amount of conveyance) to measure the speed. Thus, the control unit 13 acquires the moving amount of the main conveyance roller 17 for a predetermined rotation amount (unit rotation amount) from a rotation amount of the main conveyance roller 17 and the moving amount (conveyance amount) of the recording medium acquired from the signal from the rotary encoder 30.
The sheet is formed in a loop shape at the upstream side of the main conveyance roller 17 and at the downstream side of the sub conveyance roller 20 in the most downstream so that, when the sheet is conveyed in the periphery of the recording unit, the sheet is not influenced by the conveyance roller disposed in other than the periphery of the recording unit. Further, pressing force of the main pinch roller 18 applied to the main conveyance roller 17 is set to be a value sufficiently larger than the pressing force of the sub pinch roller 20 applied to the sub conveyance roller 19 and the pressing force of the pre-main pinch roller 22 applied to the pre-main conveyance roller 21. With this arrangement, the sheet is conveyed along with the rotation of the main conveyance roller 17.
The recording element included in the recording head is driven based on record data. By driving the recording element, the ink is discharged from the nozzles and impacts on the recording medium. A first color corresponding to the record data is recorded by a first color nozzle of the recording head. Next, a second color corresponding to the record data is recorded by a second color nozzle. By repeating the recording by a third color nozzle, a fourth color nozzle, and so on, the image is formed with the ink.
If the conveyance speed of the recording medium is V2 (speed faster than V1), to perform the recording for seven raster lines while the main conveyance roller 17 performs one rotation, the control unit 13 outputs the pulse trains RAS1 to RAST. If the conveyance speed of the recording medium is V3 (speed slower than V1), to perform the recording for five raster lines while the main conveyance roller 17 performs one rotation, the control unit 13 outputs the pulse trains RAS1 to RAS5. These raster numbers are the values that are used to illustrate the control intelligibly.
A waiting time Tw is provided from an end of a previous pulse train RAS until a start of a following pulse train RAS. For example, the period Tw is provided between the pulse train RAS1 and the pulse train RAS2, and between the pulse train RAS2 and the pulse train RAS3.
As illustrated in the
Before performing a recording operation, the control unit 13 determines the number of pulse trains, an interval Tp of the pulses, an output interval Tr of the pulse trains, and a delay time Dt while the main conveyance roller 17 performs one rotation. These parameters are determined based on information about the moving amount of the recording medium per a predetermined rotation amount (predetermined rotation angle) of the main conveyance roller 17, the conveyance speed of the recording medium, and the eccentricity of the main conveyance roller 17.
The parameters will be described. The pulse trains RAS1 and RAS2 are sequentially output to perform the recording for two raster lines (N1 raster and N2 raster) based on the edge Eg0. The control pulses included in such pulse trains have an interval Tp0. There is an interval Tr0 between the pulse train RAS1 and the pulse train RAS 2. There is a delay time of 0. Based on the edge Eg1, the pulse train RAS3 is output to perform the recording for one raster line (N3 raster). The pulse train RAS3 is output, being delayed from the timing of edge Eg1 by the delay time Dt1. There is an interval Tp1 between the control pulses included in the pulse train RAS3. Based on the edge Eg2, the pulse trains RAS4 and RAS5 are sequentially output to perform the recording for two raster lines (N4 raster and N5 raster). There is an interval Tp2 between the control pulses included in the pulse trains.
There is an interval Tr2 between the pulse train RAS4 and the pulse train RAS5. There is a delay time of 0. Based on the edge Eg3, the pulse train RAS6 is output to perform the recording for one raster line (N6 raster). The pulse train RAS6 is output, being delayed from the timing of the edge Eg3 by the delay time Dt3. There is an interval Tp3 between the control pulses included in the pulse train RAS6. According to the present exemplary embodiment, Tp0, Tp1, Tp2, and Tp3 are the same numerical value. Further, Tr0 and Tr2 are the same numerical value. However, to finely adjust the drive timing, at least one value of Tp0 to Tp3 may be set to a different value. Furthermore, Tr0 and Tr2 may be set to different values from each other.
Moreover, a part (correspondence between the edge and the pulse train) of the parameter to perform the recording for seven raster lines will be described. Based on the edge Eg0, the pulse train RAS1 and RAS2 are sequentially output to perform the recording for the two raster lines (N1 raster and N2 raster). Based on the edge Eg1, the pulse trains RAS3 and RAS4 are sequentially output to perform the recording for two raster lines (N3 raster and N4 raster). Based on the edge Eg2, the pulse trains RAS5 and RAS6 are sequentially output to perform the recording for two raster lines (N5 raster and N6 raster). Based on the edge Eg3, the pulse train RAST is output to perform the recording for one raster line (N7 raster).
The storage unit of the control unit 13 stores the parameters for performing the recording for five raster lines, the parameters for performing the recording for six raster lines, and the parameters for performing the recording for seven raster lines described above. The falling edge is used as an edge to be used for the control, however, a rising edge may be also used.
Next, speed fluctuation due to the eccentricity will be described. For example, a case is assumed in which there is difference in diameters of the main conveyance roller 17 at each phase thereof (from 0 to 90 degrees, from 90 degrees to 180 degrees, from 180 degrees to 270 degrees, and from 270 degrees to 360 degrees of an angle).
By the simple control configuration as described above, the timing signal can be output for driving the recording head with the timing corresponding to the movement (eccentricity of the main conveyance roller 17) of the recording medium. In particular, even when the number of raster lines recorded during one rotation of the roller is not divided by the number of edges of the encoder signal, the recording can be performed on the recording medium at an equal interval at resolution of 1200 dpi in the conveyance direction.
In addition, the timing of falling edges (Eg0, Eg1, Eg2, Eg3) of the encoder signal Enc may be shifted due to cogging of the stepping motor 61 that is the drive source of the main conveyance roller 17 and the eccentricity of a transmission member between the stepping motor 61 and the rotary encoder 30. However, by providing the waiting time Tw between the pulse train RAS and the pulse train RAS, even if the timing of the edge of the encoder signal is shifted, the timing of the previous pulse train RAS and the timing of the following pulse trans RAS can avoid overlapping each other, thereby preventing the recorded image from being deteriorated.
A record timing generation unit 40 includes a reference signal generation unit 41, a timing generation unit 42, a drive signal generation unit 43, a memory control unit 44, and a correction data storage unit 45.
The reference signal generation unit 41 and the timing generation unit 42 input parameters from the correction data storage unit 45 via the memory control unit 44. The parameters are information for determining the drive timing of the recording head for performing the recording at a desired position, even if the speed is fluctuated by the moving speed and the eccentricity of the recording medium.
As the parameters described above, parameters (e.g., a parameter for the recording for five raster lines and a parameter for the recording for seven raster lines) corresponding to a plurality of conveyance velocities including a parameter for performing the recording for the six raster lines described above are determined.
The reference signal generation unit 41 acquires the delay timing Dt described above based on the parameters. The timing control unit 42 acquires Tp and Tr. Based on the control parameters described above, the drive signal generation unit 43 outputs the pulse train formed of the control pulses to the transfer control unit 50. The transfer control unit 50 transfers the pulse train to the recording head 14.
The recording head 14 includes a drive circuit (not illustrated) that drives the recording element corresponding to the nozzle and a drive control circuit that controls the drive circuit. The drive control circuit controls the drive of the recording element based on the control signal transferred from a transfer control unit 50 in addition to the drive reference signal Con. The drive circuit includes the recording element and a switch (e.g., transistor) for turning on the recording element for a predetermined period. In addition, in the recording head 14, the control signal (control data) transferred from the transfer control unit 50 includes information for selecting the recording element (block) to be driven and information about the period when the drive pulse for driving the recording element is turned on.
The reference signal generation unit 41 inputs the signal from the rotary encoder 30. The memory control unit 44 inputs the signal from the speed measuring unit 25 and the roller reference sensor 31 that detects a rotation reference position of the main conveyance roller 17. The speed measuring unit 25 may be, for example, a laser Doppler speed meter.
The controller 15 generates record data from data input from the external device 16 (refer to
In addition, when the record operation is started, the conveyance speed of the recording medium is acquired at least once. An example of the acquisition timing in step S1 is the timing before a job is started in which the recording apparatus performs the recording operation. Further, the moving amount for the predetermined rotation amount (unit rotation amount) of the main conveyance roller 17 is acquired as a processing of step S2, and then, based on the moving amount, the control pulse may be generated.
As described above, the exemplary embodiment of the present invention has been described, however, the values are not limited to the values described above. Furthermore, the configuration of the printer is not limited either. For example,
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all modifications, equivalent structures, and functions.
This application claims priority from Japanese Patent Application No. 2011-027541 filed Feb. 10, 2011, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
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2011-027541 | Feb 2011 | JP | national |