JP4684462B2 - Printing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printing apparatus having means for conveying a print medium relative to a print head in the course of a printing operation.
[0002]
[Prior art]
As this type of printing apparatus, for example, the print head is moved relative to the print medium in a direction different from the arrangement direction of the plurality of print elements provided in the print head (main scan), and the main scan is performed between the main scans. There is a so-called serial printing apparatus that performs printing by relatively transporting (sub-scanning) a print medium with respect to a print head in a direction orthogonal to the direction. In such a printing apparatus, the transported print medium may bend at a portion facing the print head, and may come into contact with the print head to contaminate the print medium or interfere with main scanning of the print head. .
[0003]
Therefore, as a countermeasure, in the conveyance direction of the print medium, conveyance rollers are provided on the upstream side and the downstream side, respectively, across the portion facing the print head so that the print medium is regulated flat at the portion opposed to the print head. I was doing. Further, a tension is applied to the print medium by rotating a downstream transport roller (hereinafter referred to as a paper discharge roller) at a slightly higher speed than an upstream transport roller (hereinafter referred to as a line feed (LF) roller). Therefore, the bending of the print medium is suppressed.
[0004]
However, in such a configuration, since the tension is always applied to the print medium, the print medium is suddenly moved toward the discharge roller so that the print medium is repelled at the moment when the rear end of the print medium moves away from the LF roller as the print progresses. May occur (sometimes referred to as “kicking”), and accurate conveyance may not be performed. For this reason, the image printed on the rear end portion of the print medium may be disturbed.
[0005]
Conventionally, as one of the countermeasures, until the print medium is fed and the leading edge of the print medium reaches the discharge roller, and the rear edge of the print medium leaves the LF roller, The corresponding area on the print medium until it passes is called the “printable area” to distinguish it from the “print guarantee area” between them, and the user is recommended to print in the “printable area”. There is something that I tried not to do.
[0006]
[Problems to be solved by the invention]
However, the conventional example has the following problems.
1. The print guarantee area of the print medium is narrowed.
2. In recent years, the number of print elements provided in the print head has increased to increase the print throughput and the like, and the print head has become enormous. However, the distance between the LF roller and the discharge roller tends to increase accordingly. The print guarantee area is further narrowed.
[0007]
SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and it is an object of the present invention to reduce image quality degradation caused by a “kicking” phenomenon that occurs when a print medium leaves an LF roller, and to expand the print guarantee area of recording paper. And
[0008]
[Means for Solving the Problems]
  Therefore, the present invention provides a printing apparatus that performs printing using a print head formed by arranging a plurality of printing elements.
  Print data is set in the plurality of print elements to cause the print head to perform a print operation.Data settingMeans,
  The print headIs located upstream of the print media transport direction.Lint positionTo the aboveLint mediumTransportFeeding means;
  Disposed downstream of the print head in the transport direction,Discharging means for transporting the print medium from the print position;
  Detecting the transport state of the print mediumTransport status detectionMeans,
  A print medium detecting means disposed upstream of the feeding means for detecting the presence or absence of the print medium;
  A conveyance amount setting unit configured to set a conveyance amount of the print medium to be small after the print medium detection unit is in a state where the print medium is not detected from a state where the print medium is detected;
  Print data to be set on the plurality of print elements is shifted according to the transport state when the print medium is detached from the feeding unit.Data shiftMeans,
With,
  The data shift unit is configured to detect the plurality of print elements according to the conveyance amount set by the conveyance amount setting unit from the state where the print medium detection unit detects no more than the state where the print medium is detected. The range to be used for printing is set, and the remaining print elements are used to cope with the shift of the print data.It is characterized by that.
[0021]
In the present specification, “print” is not only formed when significant information such as characters and figures is formed, but also manifested so that human beings can perceive visually. Regardless of whether or not, an image, a pattern, a pattern, or the like is widely formed on a print medium, or the medium is processed.
[0022]
In addition, “print medium” refers not only to paper used in general printing apparatuses, but also to materials that can accept ink ejected by a head, such as cloth, plastic film, and metal plate. . However, in the following embodiments, it may be referred to as “recording paper” or simply “paper”.
[0023]
Furthermore, “ink” should be interpreted widely as the definition of “print” above, and can be used for forming an image, a pattern, a pattern, etc. or processing the print medium by being applied on the print medium. Say liquid.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0025]
(First example of embodiment)
FIG. 1 is a schematic perspective view showing a configuration example of a main part of a serial type ink jet printing apparatus as a printing apparatus to which the present invention can be applied.
[0026]
In FIG. 1, reference numeral 104 denotes a fixed lever for detachably mounting a head unit having a plurality of recording heads arranged with a plurality of ejection ports and ejecting ink droplets from the ejection ports to the carriage 103. Is stored in this lever. In the case of this embodiment, the head unit 102 integrally has four color ink recording heads of yellow (Y), magenta (M), cyan (C), and black (K), and each recording head. For example, dots are formed on the recording paper 110 serving as a print medium by the ink droplets discharged from the ink, thereby enabling printing of a color image or the like.
[0027]
In the configuration of FIG. 1, each head unit integrally includes a discharge unit that discharges ink of a predetermined color and an ink tank that stores ink to be supplied to the corresponding discharge unit. It is mounted detachably. When the ink runs out, it can be replaced with a new ink tank for each color.
[0028]
Although FIG. 2 shows an apparatus that enables full color printing by ejecting four colors of yellow, magenta, cyan, and black, the number of ink colors and the number and form of print heads are not limited to this. Of course.
[0029]
In the carriage 103, the driving force of the carriage driving motor (main scanning motor) 113 is transmitted via the motor pulley 112, the driven pulley 111 and the timing belt 107, so that the arrows a and b in FIG. It is provided so that it can move in the direction. On the other hand, the recording paper 110 as a print medium is transported in the direction f by two sets of transport rollers 106, 107 and 108, 109 provided upstream and downstream in the transport direction. Further, the back surface of the recording paper 110 is supported by a platen 302 (FIG. 2) so as to form a flat recording surface at a position facing the discharge port of the print head. Images and the like are sequentially formed on a predetermined area of the recording paper by scanning the recording paper of the print head by the movement of the carriage 103 and transporting the recording paper by the transport roller.
[0030]
The image data and the like for printing are transmitted from an electric circuit that forms a control unit of the printer body to a print head drive circuit via a flexible cable (not shown).
[0031]
A recovery unit 120 is disposed at the home position in the movement of the print head. The recovery unit 120 includes four caps 121 arranged corresponding to the ejection port arrays of the print heads of the respective ink colors, and a pump unit (not shown) connected to each cap by a tube or the like. When the carriage 103 approaches, the cap 121 can be moved up and down in accordance with the movement of the cap 121. When the print head is at the home position, a surface (hereinafter referred to as a discharge port of the corresponding print head) is provided. The discharge port surface is also in close contact with the discharge port surface (capping). By this capping, thickening or sticking due to evaporation of ink in the ejection port is prevented, thereby preventing ejection failure. Also, when the ink tank is replaced or when a print head discharge failure occurs, the pump unit is operated under the above-mentioned capping state to make the inside of the cap have a negative pressure, and the suction port by this negative pressure causes the discharge port to A suction recovery process for sucking out ink from the ink and introducing new ink is performed. Further, the recovery unit 120 is provided with a wiper blade 122 for wiping off ink droplets and the like adhering to the discharge port surface of the print head and cleaning the discharge port surface between the cap 121 and the print region.
[0032]
FIG. 2 is a schematic side view of the printing apparatus shown in FIG.
[0033]
In FIG. 2, 302 is a platen, and 307 is a paper end (PE) sensor for detecting the end of the recording paper by detecting the presence or absence of recording paper.
[0034]
A pair of transport rollers provided on the upstream side in the transport direction of the recording paper 110 are LF roller 106 for feeding the recording paper 110 toward the print position by the print head, and the recording paper in cooperation with the LF roller 106. It comprises a pinch roller 107 for nipping and conveying. Similarly, a pair of transport rollers provided on the downstream side includes a paper discharge roller 108 for discharging the recording paper 110 from a print position by the print head, and a pinch for nipping and transporting the recording paper in cooperation with the paper discharge roller 108. A roller 109. Note that the pinch roller 109 that contacts the print surface of the recording paper 110 after image formation has a spur roller shape with a small contact area in consideration of the case where the ink is not sufficiently fixed in this embodiment. be able to.
[0035]
The recording paper stacked on an ASF (automatic sheet feeder) or the like is conveyed to a position facing the head unit 110 by the LF roller 106 during printing. When the paper is further conveyed and reaches the paper discharge roller 108, the leading end of the recording paper 110 is nipped and fixed by the paper discharge roller 108 and the pinch roller 109, and the portion between the paper discharge roller 108 and the LF roller 106 is uniform. And a high-quality image can be formed. Further, in order to make a uniform flat surface more reliable, the discharge roller 108 is slightly increased with respect to the speed of the LF roller 106 to apply tension to the recording paper 110. At this time, the pressure between the LF roller 106 and the pinch roller 107 is made higher than the pressure between the pinch roller 109 and the paper discharge roller 108, and the paper discharge roller 108 side always slips, thereby recording paper. Can be controlled by the LF roller 106.
[0036]
In such a configuration, consider the moment when printing progresses and the trailing edge of the recording paper 110 leaves the LF roller 106. As described above, since the discharge roller 108 is accelerated relative to the LF roller 106, the recording paper 110 is tensioned in the direction of the discharge roller. Usually, since the rear end side of the recording paper 110 is nipped by the LF roller 106 and the pinch roller 107, feeding of the recording paper is limited to the LF roller 106, but the rear end of the recording paper 110 is nipped on the LF roller side. When the position is separated, the restriction by the LF roller 106 and the pinch roller 107 is removed. Therefore, at the moment when the trailing edge of the recording paper 110 leaves the LF roller 106, a phenomenon called “kicking”, in which the paper is abruptly transported toward the discharge roller 108 side by the tension generated by the discharge roller 108. Will occur. The amount of “kicking” is indefinite, but is within the mechanical play on the paper discharge roller side.
[0037]
FIG. 3 is a block diagram illustrating a schematic configuration example of a control circuit in the inkjet printing apparatus of FIGS. 1 and 2.
[0038]
In FIG. 3, a controller 200 is a main control unit, for example, a CPU 201 in the form of a microcomputer, a ROM 203 storing programs, required tables and other fixed data, an area for developing image data supplied from a host device 210, and a print head A RAM 205 or the like provided with a print buffer area for developing print data to be transferred to H and other work areas and the like.
[0039]
The host device 210 is a supply source of image data (in addition to being a computer that creates and processes data such as images related to printing, it may be in the form of a reader unit for image reading, a digital camera, or the like) It is. Image data, other commands, status signals, and the like are transmitted / received to / from the controller 200 via the interface (I / F) 212.
[0040]
The operation unit 220 includes a switch group that receives an instruction input by an operator, and includes a power switch 222, a switch 226 for setting online / offline with the host device 210, and the like.
[0041]
Reference numeral 230 denotes a sensor group for detecting the state of the apparatus. In addition to the above-described sensor 204 for detecting the home position, a paper end sensor 307 for detecting the presence / absence of a print medium, and a discharge roller 108 are also provided. A detection unit 234 for detecting the amount of rotation is included.
[0042]
The ejection unit (print head) H included in the head unit 102 can be configured to eject ink using, for example, thermal energy, and generates thermal energy that causes film boiling in the ink when energized. Therefore, an electrothermal converter (discharge heater) 225 can be provided. In other words, the print head H prints by causing film boiling in the ink by the thermal energy applied by the discharge heater and discharging ink from the discharge port using the pressure of bubbles generated at that time. A discharge port or a liquid passage communicating with the discharge port and a discharge heater disposed in the liquid passage (hereinafter, collectively referred to as a nozzle unless otherwise specified) constitute a printing element.
[0043]
The print head H includes a plurality of nozzles arranged in a direction different from the main scanning direction, for example, the sub-scanning direction, a shift register 242 for aligning nozzle drive data corresponding to the nozzle positions, and the aligned data. And a transistor circuit for driving each nozzle at an appropriate timing based on the latched data. A transfer unit 240 serially transfers the print data expanded in the print buffer provided in the RAM 205 to the shift register 242 of the print head H according to an appropriate clock.
[0044]
Reference numeral 250 denotes a motor driver for driving the main scanning motor 113, and reference numeral 270 denotes a motor driver for driving a transport motor 272 in the form of a pulse motor, for example.
[0045]
The configuration of the discharge roller rotation amount detection unit will be described with reference to FIG.
[0046]
In the figure, reference numeral 402 denotes a transmission unit that converts the speed of the conveyance motor 272 in the form of a pulse motor into appropriate rotation speeds of the LF roller 106 and the paper discharge roller 108. A disc-shaped sheet 404 is provided coaxially with the paper discharge roller 108 and rotates at the same time and is provided with a plurality of slits along the circumferential direction. The slit is positioned on the optical axis of the photo interrupter 406. Is provided. That is, the photo interrupter 406 outputs a pulsed signal as the sheet 404 rotates. Reference numeral 407 denotes a counter that counts the pulse-shaped output signal. The count value is transmitted to the CPU 201 and can be appropriately cleared by the CPU 201.
[0047]
In such a configuration, when the “kicking” phenomenon described with reference to FIG. 3 occurs, the discharge roller 108 exhibits a rotation amount different from the normal amount. This is because there is mechanical backlash.
[0048]
FIG. 5 shows the relationship between the output of the photo interrupter 406 and the drive signal of the pulse motor 401 at this time. In the section (a) in the figure (a section in which the recording paper is nipped and conveyed between the LF roller 106 side and the paper discharge roller 108 side; hereinafter referred to as a normal section), a photointerrupter for three pulses for each drive pulse of the pulse motor. Although an output is obtained, if “kicking off” occurs, the rotation is extra by the mechanical backlash, so that a larger number of pulses than usual is obtained. The section (b) in the figure corresponds to this, and in this embodiment, a state where there are four pulses is shown.
[0049]
In the present embodiment, this “kicking” phenomenon is dealt with by controlling the print head H to shift image data.
[0050]
FIG. 6 is a schematic configuration example of a print buffer and the like for realizing such control.
[0051]
In this figure, PB is a print buffer provided in the RAM 205, and TB is a transmission buffer for transferring data set from the print buffer PB to the print head H during the printing operation, and is provided in the transfer unit 240. The plurality of nozzles of the print head H are divided into 20 bands in units of 8 nozzles from the nozzle located at the end of the arrangement range (for example, the end on the most upstream side in the print medium conveyance direction). Shall be.
[0052]
The print buffer PB in this embodiment includes areas B0 to B19 each having a size of 1 byte (8 bits) in the sub-scanning direction in order to develop image data corresponding to the nozzle arrangement configuration of the print head H. A dummy data area dummy having a size of 1 byte in the sub-scanning direction is used in order to cause the print head H to appropriately perform a printing operation even for an extra transport amount (hereinafter referred to as a kicking amount) due to the “kicking” phenomenon. Is provided. The transmission buffer TB has 1-byte (8-bit) areas Band0 to Band20.
[0053]
In such a configuration, in the normal section, the 1-byte data in the area B0 on the print buffer PB is set in the area Band0 on the transmission buffer TB without setting the dummy data (NULL data) on the area dummy in the transmission buffer TB. , Assigned to the uppermost 8 nozzles (8 nozzles located on the uppermost stream side in the print medium transport direction) of the print head H. Hereinafter, 1-byte data in the area B1 of the print buffer PB is set in the area Band1 of the transmission buffer TB. And the next 8 dots of the print head H are assigned.
[0054]
On the other hand, when the “kicking” phenomenon occurs, the recording paper 110 is transported by the paper discharge roller, so that the recording paper 110 is transported by the increased speed, and several nozzles are displaced from the original print position. become. Therefore, in this embodiment, the data in the print buffer prepared for printing in the normal section is shifted by several nozzles from the highest nozzle.
[0055]
In other words, in the present embodiment, if the dot position needs to be corrected in response to the occurrence of the “kicking” phenomenon and the extra conveyance of several nozzles, the area dummy, In order to perform data transfer to the shift register 142 provided on the print head H, the data in the areas B0,..., B19 are set in the areas Band0, Band1,. The position of the data set in the print head H is corrected by reducing the number of clocks by an amount necessary for dot position correction.
[0056]
That is, for example, when an extra transport corresponding to three nozzles is performed, the number of transfer clocks is reduced by “8-3 = 5”, and data transfer in the areas Band0 to Band20 of the transmission buffer TB is performed. . Here, since the amount of data is larger by the amount of dummy data than the number of nozzles of the print head H, the dummy data for the upper 5 bits is discharged from the shift register and disappears. NULL data is set for these three nozzles, and data corresponding to the image data is set for the nozzles below that. Therefore, the print data can be appropriately positioned with respect to the nozzle position of the print head without re-editing the print buffer or the like.
[0057]
Note that not all of the data in the last print buffer area B19 to be transferred is printed, but this is done by clearing only the data area already printed in the print buffer, for example. You can print with
[0058]
In addition, the number of data transfer clocks corresponding to the “kicking” amount can be appropriately adjusted according to the number of pulses obtained in the section (b) of FIG.
[0059]
FIG. 7 shows an example of a control procedure for preventing the occurrence of image defects due to the “kicking” phenomenon.
[0060]
When this procedure is activated in response to the input of the print command, line feed (LF) is first performed until the PE sensor 307 detects the recording paper 110 (steps S702 and S703). When the PE sensor 307 detects the leading edge of the recording paper 110 (step S703), the PE sensor 307 further conveys the portion facing the print head H (step S704). Since the distance from the PE sensor 307 to the portion facing the print head H is fixed, the transport amount at this time may be stored in advance in the ROM 203 or the like.
[0061]
When the recording paper 110 reaches the position facing the print head H, the PE sensor 307 alternates between printing of one main scan (pass) by the print head H and conveyance of the normal amount of recording paper, and the PE sensor 307 detects the trailing edge of the recording paper 110. This is performed until it is detected (steps S705, S706, and S707). Even if the trailing edge of the recording paper 110 is detected, the recording paper 110 is present at the portion facing the print head H, so further printing is performed (steps S708 and S709).
[0062]
At this time, in order to detect the occurrence of the “kicking” phenomenon, the paper discharge roller rotation amount detecting means described above is used after the trailing edge is detected. The count value in the normal section obtained based on the photo interrupter output is set to “I_CONT”, and the count value “CONT” obtained by the conveyance in step S709 is compared with “I_CONT” (step S710).
[0063]
If “CONT” is equal to “I_CONT” (step S710), it is determined that the “kicking” phenomenon has not occurred, and the process returns to step S708. On the other hand, if “CONT” and “I_CONT” are not equal (step S710), it is determined that the “kicking” phenomenon has occurred, and the image shift control described with reference to FIG. The position of the image is shifted according to the count value (step S711).
[0064]
Thereafter, the conveyance and the main scanning are repeated until the printing is completed (steps S712 to S714). When the printing is completed, the recording paper is discharged (step S716) to complete a series of operations.
[0065]
Note that after the “kicking” phenomenon occurs, the conveyance amount is ideally constant, but the recording paper 110 is not sufficiently held after the trailing edge of the recording paper is separated from the nipping position by the LF roller 106, so that the conveyance is not performed. May become unstable. For this reason, in this embodiment, after the “kicking” phenomenon is detected in step S710, the conveyance amount is detected after each main scan (step S715), and if the conveyance disturbance is detected, the image shift is similarly performed. It is supposed to be.
[0066]
By performing the above control, it is possible to reduce the degradation of the image quality due to the “kicking” phenomenon that occurs when the recording paper leaves the LF roller, and it is possible to expand the print guarantee area of the recording paper.
[0067]
As another countermeasure, the rotation amount of the paper discharge roller is monitored by a rotary encoder or the like, and when an abnormal rotation amount is detected, it is determined that “kicking” has occurred, and the print data set in the print head By adjusting the position, it is possible to prevent image distortion.
[0068]
In the above example, the dummy data area is provided in the print buffer PB. However, dummy data generating means is provided only on the transfer unit side so that dummy data is transferred prior to original image data transfer. At the same time, the number of clocks may be controlled corresponding to the position correction in the same manner as described above. For example, in this case, an area in which dummy data is fixedly generated may be positioned above the transmission buffer.
[0069]
Further, in the above example, the dummy data is set to 8 bits in the sub-scanning direction, but the number of bits can be appropriately set according to the position correction amount.
[0070]
(Second example of embodiment)
In addition to the first embodiment described above, for example, the nozzles are arranged in a range larger than the range necessary for printing in the normal section on the print head, and the nozzles arranged in the enlarged range are used as correction nozzles. By doing so, it is effective to be able to prevent the loss of images due to the separation from the part facing the original print head due to extra conveyance.
[0071]
However, if the “kick-off” amount is larger than the correction nozzle arrangement range, it may not be possible to adjust the data position on the print head. From the viewpoint of downsizing the print head, the number of correction nozzles is A smaller one is considered preferable.
[0072]
The second example of the embodiment of the present invention adopts a configuration in view of this point.
In addition, about the apparatus and the control system, the structure similar to the said 1st example is employable.
[0073]
FIG. 8 is a schematic configuration example of a basic print buffer and the like employed for realizing the control in this example.
[0074]
In this figure, PB2 is a print buffer, and TB2 is a transmission buffer for transferring data set from the print buffer PB2 to the print head H2. Note that the print head H2 has 16 nozzles arranged on the downstream side in the transport direction in order to perform correction in addition to the nozzles arranged in a normally used range.
[0075]
In the present embodiment, the print buffer PB2 has regions B0 to B19 each having a size of 1 byte (8 bits) in the sub-scanning direction in order to develop image data corresponding to the normally used nozzle arrangement of the print head H. Have The transmission buffer TB2 has 1-byte (8-bit) areas Band0 to Band19, and a dummy data area capable of generating 2-byte (16-bit) NULL data before and after the area.
[0076]
In such a configuration, in the normal section, 1-byte data in the area B0 on the print buffer PB2 is set in the area Band0 on the transmission buffer TB2 and assigned to the most significant 8 nozzles in the normal use range of the print head H2. The 1-byte data in the area B1 of the buffer PB2 is set in the area Band1 of the transmission buffer TB2, and is assigned to the next 8 nozzles of the print head H2.
[0077]
On the other hand, when the “kicking” phenomenon occurs, the recording paper 110 is transported by the paper discharge roller, so that the recording paper 110 is transported by the increased speed, and several nozzles are displaced from the original print position. become. Therefore, in this embodiment, the data in the print buffer prepared for printing in the normal section is further shifted by several nozzles from the uppermost nozzle in the normal use range.
[0078]
In this embodiment, 16 dots of dummy data are added before and after the original image data and transferred. At this time, if the number of transfer clocks corresponds to the normal interval, the dummy data added to the end of the image data is not transferred to the print head H2, and the dummy data added to the head (NULL data) is the highest head. Data on the correction nozzle on the side (downstream in the transport direction) is cleared. When the “kicking” phenomenon occurs, the number of data transfer clocks is increased and the image data set position on the print head H2 is shifted. At this time, the dummy data (NULL data) added to the tail of the image data clears the data for the nozzles on the lower head side (upstream side in the transport direction).
[0079]
The number of data transfer clocks corresponding to the “kicking” amount can be adjusted as appropriate according to the number of pulses obtained in the section (b) of FIG. 5, as in the first example.
[0080]
FIG. 9 is a diagram for explaining the “kicking amount” that can be corrected by the above-described configuration.
[0081]
The above-described configuration shifts the image data on the nozzle row of the print head H2 in accordance with the “kick-off” amount. Therefore, the correctable “kick-off” amount is within the arrangement range of the correction nozzles.
[0082]
In FIG. 9, the recording paper 110 is conveyed from the right side to the left side. The “kick-off” amount increases in the order of (a) to (c). In (a) and (b), the “kick-off” amount is within the arrangement range of the correction nozzles, and can be dealt with by shifting the image data as described above. However, in the case of (c), since the “kick-off” amount exceeds the arrangement range of the correction nozzles, it cannot be dealt with by the shift of the image data, and an image is lost. In order to prevent such a state as shown in (c), it is desirable to suppress the “kicking” amount within a range that can be corrected by shifting the image data.
[0083]
The “kicking” phenomenon occurs because the discharge roller is accelerated as described with reference to FIG. The amount of “kicking off” is proportional to the tension acting on the recording paper. Therefore, if the tension acting on the recording paper is reduced, the “kicking” amount can be reduced.
[0084]
Therefore, in this embodiment, control is performed to reduce the amount of conveyance (line feed (LF) amount) at the position where the “kicking” phenomenon occurs, and to reduce the tension acting on the recording paper due to the increased speed of the paper discharge roller. Do.
[0085]
FIG. 10 shows an example of such a control procedure.
[0086]
This control procedure is substantially the same as the processing procedure of FIG. 7 according to the first example. That is, after the start of this procedure according to the input of the print command, first, the line feed (LF) until the PE sensor 307 detects the recording paper 110 (steps S802 and S803), and the position up to the portion facing the print head H. Carrying (step S804).
[0087]
When the recording paper 110 reaches the position facing the print head H, the PE sensor 307 alternately prints one main scan (pass) by the print head H2 and transports the normal amount of recording paper 110. Until it is detected (steps S805, S806, S807). The amount of recording paper transport performed in this process is set to an amount “LN” corresponding to the normal use nozzle range.
[0088]
Even if the trailing edge of the recording paper 110 is detected, the recording paper 110 is present at a portion facing the print print head H, and therefore, main scanning and transport operations are performed (steps S808 and S809). However, after the trailing edge is detected, the recording paper conveyance amount is set to an amount “LE” smaller than the normal amount “LN”. The “LE” amount is determined according to the mechanical configuration of the transport system, the shape of the head, and the like, and may be stored in advance in the ROM 203 or the like. Further, the use nozzle range at the time of main scanning may be determined according to the transport amount.
[0089]
Further, as in the first example, the count value in the normal section obtained based on the above-described photointerrupter output is “I_CONT”, and the count values “CONT” and “I_CONT” obtained by the conveyance in step S809 are By comparing, the occurrence of the “kicking” phenomenon is detected (step S810). If it is determined that the “kicking” phenomenon has not occurred, the process returns to step S808. On the other hand, if it is determined that the “kicking” phenomenon has occurred, the image shift control described with reference to FIG. The position of the image set on the print head H2 is shifted according to the count value (step S811).
[0090]
Thereafter, the LE amount of recording paper conveyance and main scanning are repeated until printing is completed (steps S812 to S814). When the printing is completed, the recording paper is discharged (step S816) to complete a series of operations. Similarly to the first example, after detecting the “kicking” phenomenon in step S810, the conveyance amount is detected after each main scan (step S815), and if the conveyance disturbance is detected, the image shift is performed similarly. I have to.
[0091]
By performing the above control, it is possible to reduce the degradation of the image quality due to the “kicking” phenomenon that occurs when the recording paper leaves the LF roller, and it is possible to enlarge the print guarantee area of the recording paper. In addition, the amount of “kicking” can be reduced by reducing the transport amount after detection of the trailing edge of the recording paper and reducing the tension acting on the recording paper due to the increased speed of the paper discharge roller. Therefore, it is possible to reliably cope with the “kicking” phenomenon by adjusting the data position using the nozzle. Alternatively, the arrangement range of the correction nozzles can be reduced to contribute to the downsizing of the print head.
[0092]
(Third example of embodiment)
FIG. 11 is a diagram for explaining how to deal with the “kicking” phenomenon by using the print head H3 in which correction nozzles are arranged in addition to the normally used nozzles.
[0093]
When the head shown in the figure is used to cope with the shift of image data on the nozzle array of the head basically in accordance with the kicking amount, the correctable “kicking” amount is within the arrangement range of the correction nozzles. That is, correction is performed by shifting the number of nozzles to be used in accordance with the “kicking” amount, and therefore, a dedicated nozzle for correction that is not normally used is provided. Accordingly, it can be said that by providing the nozzle dedicated for correction in this way, the print width per one main scan (normal use nozzle range) is smaller than the width of all nozzle rows, and accordingly, the print throughput is reduced accordingly. .
[0094]
In the third example of the embodiment of the present invention, the “kicking” phenomenon is dealt with while suppressing a decrease in throughput.
[0095]
FIG. 12 shows an example of a control procedure for performing such a countermeasure.
[0096]
This control procedure is also similar to the processing procedure of FIG. 7 according to the first example. That is, after the start of this procedure according to the input of the print command, first, the line feed (LF) until the PE sensor 307 detects the recording paper 110 (steps S902 and S903), and the conveyance to the portion facing the print head. (Step S904) is performed.
[0097]
When the recording paper 110 reaches the position facing the print head, the PE sensor 307 alternates between printing of one main scan (pass) by the print head H4 and conveyance of the normal amount of recording paper, and the PE sensor 307 detects the trailing edge of the recording paper 110. This is performed until it is detected (steps S905, S906, S907). The amount of recording paper transport performed in this process is set to an amount corresponding to the entire nozzle row range.
[0098]
Even if the rear end of the recording paper 110 is detected, the recording paper 110 is present at the portion facing the print print head H, so that the printing operation is performed. In this example, first, a correction nozzle is secured in the nozzle array (step). S908). The number of correction nozzles to be secured may be stored in advance in the ROM 203, for example. Then, the printing operation is performed while carrying out the transport operation and the main scanning (steps S909 and S919). However, after securing the correction nozzle based on the trailing edge detection, the recording paper conveyance amount is set to a predetermined amount obtained by subtracting the correction nozzle range. Further, unless the “kicking” phenomenon is detected, the image data is basically set for nozzles other than those reserved for correction.
[0099]
Further, as in the first example, the count value in the normal section obtained based on the above-described photointerrupter output is set to “I_CONT”, and the count values “CONT” and “I_CONT” obtained by the conveyance in step S909 are set. By comparing, the occurrence of the “kicking” phenomenon is detected (step S911). If it is determined that the “kicking” phenomenon has not occurred, the process returns to step S909. On the other hand, if it is determined that the “kicking” phenomenon has occurred, the nozzle secured for correction is also used as in the above example. By performing this image shift control, the position of the image set on the print head is shifted according to the count value (step S912).
[0100]
Thereafter, until the printing is completed, a predetermined amount of recording paper conveyance and main scanning are repeated (steps S913 to S915), and when the recording is completed, the recording paper is discharged (step S916) to complete a series of operations. As in the first and second examples, after detecting the “kicking” phenomenon, the conveyance amount is detected after each main scan, and the image shift is performed in the same manner when the conveyance disturbance is detected. Good.
[0101]
By performing the above control, it is possible to reduce the degradation of the image quality due to the “kicking” phenomenon that occurs when the recording paper leaves the LF roller, and it is possible to enlarge the print guarantee area of the recording paper. In addition, after detecting the trailing edge of the recording paper, the amount of conveyance is reduced by securing a correction nozzle, so the tension acting on the recording paper due to the increased speed of the paper discharge roller is reduced, and the amount of `` kicking off '' is reduced. Can be reduced. Further, during normal times (until the trailing edge of the recording paper is detected), printing is performed in the entire nozzle row range, so that a reduction in throughput can be suppressed.
[0102]
(Fourth example of embodiment)
In the third example, the entire nozzle range is normally used, and the correction nozzle is secured after detection of the trailing edge of the recording paper. However, in the fourth example of the embodiment of the present invention, the correction to be secured is described. A configuration is adopted in which a decrease in throughput is more effectively suppressed by appropriately adjusting the number of nozzles for use.
[0103]
FIG. 13 is a diagram for explaining how to deal with the “kicking” phenomenon according to this example. If the number of nozzles to be secured for correction is adjusted for each mode with different carry amounts, it is possible to more effectively suppress a decrease in throughput by using the minimum necessary number of nozzles for correction.
[0104]
FIG. 14 shows an example of a control procedure according to this example.
[0105]
This control procedure is similar to the processing procedure of FIG. 12 according to the third example, but in this example, the print mode is first set after the start of this procedure according to the input of the print command (step S1002). ). The setting of the print mode includes selection of a high-speed print mode, a normal print mode, a high-quality print mode, and the like, and the amount of conveyance to be performed after each main scan is recognized here. In addition, as in the above example, line feed (LF) until the PE sensor 307 detects the recording paper 110 (Steps S1003 and S1004), and conveyance to a portion facing the print head H4 (Step S1005). Do.
[0106]
When the recording paper 110 reaches the position facing the print head, the PE sensor 307 detects the trailing edge of the recording paper 110 alternately with printing of one main scan (pass) by the print head and the conveyance of the normal amount of recording paper. (Steps S1006, S1007, S1008). The amount of recording paper transport performed in this process is set to an amount corresponding to the entire nozzle row range.
[0107]
Even if the trailing edge of the recording paper 110 is detected, the recording paper 110 is present at the portion facing the print print head, so that the printing operation is performed. . The number of correction nozzles to be secured is the number corresponding to the set print mode. Then, the printing operation is performed while carrying out the transport operation and the main scanning (steps S1010 and S1011). However, after securing the correction nozzle based on the trailing edge detection, the recording paper conveyance amount is set to an amount obtained by subtracting the range of the correction nozzle secured from the entire nozzle range. Further, unless the “kicking” phenomenon is detected, the image data is basically set for nozzles other than those reserved for correction.
[0108]
Further, as in the third example, the count value in the normal section obtained based on the above-described photointerrupter output is “I_CONT”, and the count values “CONT” and “I_CONT” obtained by the conveyance in step S1010 are By comparing, occurrence of the “kicking” phenomenon is detected (step S1012). If it is determined that the “kicking” phenomenon has not occurred, the process returns to step S1010. On the other hand, if it is determined that the “kicking” phenomenon has occurred, the nozzle secured for correction is also used as in the above example. By performing this image shift control, the position of the image set on the print head is shifted according to the count value (step S1013).
[0109]
Thereafter, the recording paper conveyance and the main scanning are repeated until the printing is completed (steps S1014 to S1016). When the printing is completed, the recording paper is discharged (step S1017) to complete a series of operations. As in the first and second examples, after detecting the “kicking” phenomenon, the conveyance amount is detected after each main scan, and the image shift is performed in the same manner when the conveyance disturbance is detected. Good.
[0110]
By performing the above control, it is possible to reduce the degradation of the image quality due to the “kicking” phenomenon that occurs when the recording paper leaves the LF roller, and it is possible to enlarge the print guarantee area of the recording paper. In addition, after the detection of the trailing edge of the recording paper, the conveyance amount is reduced by securing an appropriate number of correction nozzles, so the tension acting on the recording paper due to the increased speed of the discharge roller is reduced, and `` The amount of kicking can be reduced. Also, during normal times (until the trailing edge of the recording paper is detected), printing is performed in the entire nozzle array range, but after the trailing edge is detected, an appropriately set number of correction nozzles are used, which reduces throughput. Furthermore, it can suppress effectively.
[0111]
(Other)
In addition, the numerical values (the number of nozzles, the number of bits, etc.) given in the above-mentioned examples are examples, and it is needless to say that they can be appropriately set.
[0112]
In the embodiment described above, the case where the present invention is applied to an ink jet printing apparatus that forms an image by ejecting ink from a print head onto a print medium has been described. However, the present invention is limited to the configuration. is not. Any printing apparatus, such as a thermal type or a thermal transfer printing apparatus, is effective as long as printing is performed by conveying the print medium relative to the print head.
[0113]
【The invention's effect】
As described above, according to the present invention, it is possible to reduce the degradation of image quality due to the “kicking” phenomenon that occurs when the print medium leaves the LF roller, and it is possible to expand the print guarantee area on the print medium.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view illustrating a configuration example of a main part of a serial type ink jet printing apparatus as a printing apparatus to which the present invention can be applied.
FIG. 2 is a schematic side view of the printing apparatus shown in FIG.
FIG. 3 is a block diagram illustrating a schematic configuration example of a control circuit in the ink jet printing apparatus of FIGS. 1 and 2;
4 is a schematic diagram illustrating a configuration example of a discharge roller rotation amount detection unit applied to the apparatus of FIG. 1;
5 is a diagram for explaining the relationship between the detection unit output of FIG. 4 and the conveyance motor drive signal when the “kicking” phenomenon occurs.
FIG. 6 is an explanatory diagram illustrating a schematic configuration example of a print buffer and the like for realizing control according to the first example of the embodiment of the present invention that deals with the “kicking” phenomenon;
FIG. 7 is a flowchart showing a control procedure according to the first example of the embodiment of the present invention.
FIG. 8 is an explanatory diagram illustrating a schematic configuration example of a print buffer or the like for realizing control according to a second example of an embodiment of the present invention that deals with the “kicking” phenomenon;
FIG. 9 is a diagram for explaining a “kicking amount” that can be corrected by the arrangement of a correction nozzle.
FIG. 10 is a flowchart showing a control procedure according to a second example of the embodiment of the present invention for dealing with the “kicking” phenomenon.
FIG. 11 is a diagram for explaining the premise of the third example of the embodiment of the present invention.
FIG. 12 is a flowchart showing a control procedure according to a third example of the embodiment of the present invention.
FIG. 13 is a diagram for explaining a control mode according to the fourth example of the embodiment of the present invention.
FIG. 14 is a flowchart showing a control procedure according to a fourth example of the embodiment of the present invention.
[Explanation of symbols]
H, H2, H3, H4 print head
PB, PB2 print buffer
TB, TB2 transmission buffer
103 Carriage
102 head unit
106 LF roller
107 Pinch roller
108 Paper discharge roller (spur roller)
109 Pinch roller
110 Recording paper
113 Carriage drive motor (main scanning motor)
200 controllers
201 CPU
203 ROM
205 RAM
234 Discharge roller rotation amount detection unit
240 Transfer section
242 Shift register
272 Conveyor motor
302 platen
307 Paper end (PE) sensor
402 Transmission unit
404 disc-shaped sheet
406 Photointerrupter
407 counter

Claims (11)

In a printing apparatus that performs printing using a print head in which a plurality of print elements are arranged,
Data setting means for setting print data in the plurality of print elements in order to cause the print head to perform a printing operation;
Than said printhead is disposed on the upstream side in the transport direction of the print medium, a feeding means for conveying the print medium in the print position,
A discharge unit disposed downstream of the print head in the transport direction and configured to transport the print medium from the print position;
A conveyance state detecting means for detecting a conveyance state of the print medium;
A print medium detecting means disposed upstream of the feeding means for detecting the presence or absence of the print medium;
A conveyance amount setting unit configured to set a conveyance amount of the print medium to be small after the print medium detection unit is in a state where the print medium is not detected from a state where the print medium is detected;
Data shift means for shifting print data set in the plurality of print elements in accordance with the transport state when the print medium is detached from the feeding means;
The equipped,
The data shift unit is configured to detect the plurality of print elements according to the conveyance amount set by the conveyance amount setting unit from the state where the print medium detection unit detects no more than the state where the print medium is detected. A printing apparatus characterized in that a range to be used for printing is set and the remaining printing elements are used to cope with the shift of the print data .   The printing apparatus according to claim 1, wherein a conveyance speed by the discharge unit is set higher than a conveyance speed by the feeding unit. The printing apparatus according to claim 1 , wherein each of the feeding unit and the discharging unit includes a pair of rollers that sandwich and convey the print medium. It said print medium detecting means, wherein said from when a state of not detecting from state detects the print medium, any one of claims 1 to 3, characterized in that the detection by said conveying state detecting means Printing device. The printing apparatus according to claim 3, wherein the conveyance state detection unit includes a unit that detects a rotation amount of a roller constituting the discharge unit. The rotation amount detecting means is arranged so as to be coaxial with the roller and rotate at the same time and is provided with a plurality of slits along the circumferential direction, and the slits are positioned on the optical axis. 6. The method according to claim 5 , further comprising: a photo interrupter; and a counter that counts a signal output from the photo interrupter as the member rotates, and detecting the rotation amount based on the count value. The printing apparatus as described. Said data shifting means, said data setting means of claim 1 to 6, characterized in that the shift by controlling the number of clocks used for transferring data to the plurality of printing elements A printing apparatus according to any one of the above. When performing the process of shifting the print data, the print data is set for the other print elements except for a part of the plurality of print elements to perform a print operation, and the print elements printing apparatus according to any one of claims 1 to 7, characterized by using to correspond to the shift of the print data. According to another aspect of the present invention, there is provided means for setting a range of print elements to be used in response to the shift of the print data in accordance with the amount of change in the conveyance state when the print medium is detached from the feeding means. The printing apparatus according to claim 8 . Said print head, the print apparatus according to any one of claims 1, characterized in that the form of the ink jet print head for performing printing by ejecting ink onto the print medium 9. The printing apparatus according to claim 10 , wherein the inkjet print head includes a heating element that generates thermal energy that causes film boiling in the ink as energy used to eject the ink.

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