JP4686856B2 - Inkjet printer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet printer, and more particularly to an ink jet printer capable of correcting a positional deviation of nozzles.
[0002]
[Prior art]
In recent years, printers that can receive digital image data and perform full-color printing have been used. Digital image data is subjected to image processing by an internal CPU, and full color printing is performed on a recording sheet from, for example, an inkjet head (hereinafter referred to as a head). A resolution of 300 dpi or more has been used.
[0003]
[Problems to be solved by the invention]
By the way, in a head that enables full color printing, ink ejection nozzles of three or more colors are arranged side by side in the main scanning direction. Here, the problem is nozzle misalignment. For example, when the nozzles are arranged in the order of YMCK in the main scanning direction, each nozzle must be installed at a distance from the adjacent nozzle in the main scanning direction. Then, in order to spray ink to the same position, it is necessary to shift the ink discharge timing of each nozzle with respect to the moving head. This is called nozzle misalignment correction.
[0004]
On the other hand, in the prior art, the drive data for driving the nozzles is corrected according to the displacement of the nozzles. The conventional correction method will be specifically described. FIG. 5 is a diagram schematically showing the arrangement of nozzle rows arranged in the head. FIG. 6 is a diagram illustrating a discharge start signal of each nozzle row.
[0005]
In FIG. 5, nozzles n1 to n4 are arranged in the head H1 in four rows along the main scanning direction in the order of YMCK, and the head H2 has nozzles n5 in the order of YMCK in the four rows along the main scanning direction. To n8 are arranged. Here, with the first nozzle n1 as a reference, the subsequent nozzles n2 to n8 are spaced apart by distances (corresponding to positional deviations) G2 to G8 in the main scanning direction. Such distances G2 to G8 are difficult to keep at a constant value due to problems such as the accuracy of parts and assembly accuracy.
[0006]
Therefore, in the prior art, the distances G2 to G8 are measured at the time of manufacture, stored in a nonvolatile memory, and a discharge reference signal generated based on the distance G2 to G8 is provided from the control unit to each nozzle drive unit. In other words, the ejection timing of each nozzle is delayed by the head movement time corresponding to the distances G2 to G8, thereby forming an appropriate image. However, in this conventional correction method, it is necessary to connect a signal line for distributing the discharge timing to each nozzle drive unit, and depending on the type of ink jet printer, as many as 32 signal lines are required. There is a problem that the configuration becomes large.
[0007]
Further, such a conventional correction method is effective when ink is ejected by moving the head from the left to the right (forward direction) with respect to the recording medium. On the other hand, an ink jet printer has been developed in which the printing speed is improved by discharging ink from nozzles not only when the head moves in the forward direction but also when the head moves in the backward direction. However, in such an ink jet printer, when trying to correct the nozzle misalignment with the drive data, the conventional correction method described above is effective when moving in the forward direction, but it is difficult to correct the nozzle misalignment when moving in the backward direction. There is a problem that.
[0008]
The present invention has been made in view of such a problem, and even when forming an image by ejecting ink from the head during reciprocating movement while having a compact configuration, the positional deviation of the nozzles, An object of the present invention is to provide an ink jet printer that can be easily corrected by processing data.
[0009]
[Means for Solving the Problems]
In order to achieve this object, an ink jet printer according to the present invention is an ink jet printer including a plurality of nozzles capable of ejecting ink based on image data in the main scanning direction and having a head movable in the main scanning direction. ,
Storage means for storing correction data corresponding to the positional deviation of each nozzle;
Reading means for reading image data;
A plurality of combining means provided for each nozzle of a plurality of nozzles arranged in the main scanning direction for combining the read image data and the correction data;
CPU for controlling the timing of outputting the correction data combined with the image data by the combining means to each nozzle ,
The correction data is 16 × n + m numerical values n and m (both integers greater than or equal to 0), where the input unit of image data read from the reading unit and input to each of the combining units at a time is 16 bits. ) Is stored, and is data for moving the head in the main scanning direction in a state where ink is not ejected from the nozzles.
The composition of the image data and the correction data by the combining means is performed at the timing of inputting the image data from the reading means based on the stored n and m values of the correction data with respect to the moving direction of the head. In this case, the n + 1th image data input from the reading means is shifted backward by m bits with respect to the moving direction of the head, and correction data is forwardly generated. The overflowed m-bit image data is created by adding the n + 2th input image data to the front after shifting it backward by the overflow m bits. The correction data is output by the CPU at a timing common to each nozzle .
[0010]
[Action]
An ink jet printer according to the present invention includes a plurality of nozzles capable of ejecting ink based on image data in a main scanning direction and a head that is movable in the main scanning direction. Storage means for storing the corresponding correction data, read-out means for reading out the image data, and combining means for combining the read-out image data and the correction data, the correction data being ink from the nozzles This is data for moving the head in the main scanning direction in a state where no ink is ejected, and the head is driven to form an image based on the combined image data. By storing the correction data corresponding to the ink data, when the ink is actually ejected, the correction data is read and the image data is read out. And forming an image based on the synthesized image data, it is possible to form an appropriate image without the influence of the nozzle position shift without requiring a separate signal of the shift timing. Simplification, configuration downsizing, and cost reduction can be achieved. The data for moving the head in the main scanning direction without ejecting ink from the nozzles means, for example, data corresponding to gradation 0 in image data, but is not limited thereto.
[0011]
Further, if the correction data is added before the image data with respect to the moving direction of the head, it is possible to correct the positional deviation of the nozzle not only in the forward direction but also in the backward direction. The image forming speed can be increased.
[0012]
Therefore, it is preferable that the nozzles of the head eject ink based on the synthesized image data in both directions in the main scanning direction.
[0013]
Furthermore, when post data is added after the image data in order to prevent ink from being ejected from the nozzle in the moving direction of the head, for example, inappropriate data is prevented from being transmitted to the nozzle drive unit. It is preferable because it is possible.
[0014]
Further, it is preferable that nozzles capable of ejecting a plurality of colors of ink are arranged in the main scanning direction.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a mechanical configuration example near the head in the ink jet printer according to the present embodiment. The carriage 2 is a resin case that houses the head 10 and a head driver (not shown). A head driver, which is a driving means housed in the carriage 2, is composed of, for example, an IC including a parallelism 18 to be described later, and is connected to the control board 9 by a flexible cable 5 drawn from the carriage 2.
[0016]
The carriage 2 is reciprocated by the carriage drive mechanism 6 in the main scanning direction (X direction) indicated by an arrow in the figure. The carriage drive mechanism 6 includes a motor 6a, a pulley 6b, a toothed belt 6c, and a guide rail 6d, and the carriage 2 is fixed to the toothed belt 6c.
[0017]
When the pulley 6b is rotated by the motor 6a, the carriage 2 fixed to the toothed belt 6c is moved along the arrow X direction in the figure. The guide rail 6d is two cylinders parallel to each other and penetrates the insertion hole of the carriage 2 so that the carriage 2 slides.
[0018]
For this reason, the toothed belt 6c is not bent by the weight of the carriage 2, and the reciprocating direction of the carriage 2 is in a straight line. The direction in which the carriage 2 moves can be changed by reversing the rotation direction of the motor 6a, and the moving speed of the carriage 2 can be changed by changing the number of rotations. The ink cartridge 4 (not shown) has an ink tank inside. The ink supply port of the ink tank opens when the ink cartridge 4 is set on the carriage 2 and is connected to the ink supply pipe, and is closed when the connection is released, and ink is supplied to the head 10.
[0019]
The carriage 2 is provided with a head 10. On the back surface of the head 10, ink cartridges containing inks of Y, M, C, and K for ejection are detachably disposed. Note that the illustration of the ink cartridge is omitted. The flexible cable 5 is applied to data transfer means and is a flexible film in which a wiring pattern including a data signal line, a power supply line, etc. is printed, and data is transferred between the carriage 2 and the control board 9. The movement of the carriage 2 is followed.
[0020]
The encoder 7 is a resin transparent film with a scale at predetermined intervals, and the scale is detected by an optical sensor provided on the carriage 2 to detect the moving speed, position and moving direction of the carriage 2. The paper transport mechanism 8 is a mechanism for transporting the recording paper P in the sub-scanning direction indicated by an arrow Y in the figure, and includes a transport motor 8a and transport roller pairs 8b and 8c. The transport roller pair 8b and the transport roller pair 8c are driven by a transport motor 8a and are roller pairs that are substantially equal to each other by a gear train (not shown), but the transport roller pair 8c rotates at a slightly faster peripheral speed.
[0021]
The recording paper P is sandwiched between a pair of transport rollers 8b that have been fed from a paper feed mechanism (not shown) and rotated at a constant speed, and the direction of transport in the sub-scanning direction is controlled by a paper feed guide (not shown). After being corrected, the sheet is sandwiched and transported by the transport roller pair 8c.
[0022]
Since the peripheral speed of the conveyance roller pair 8c is slightly faster than that of the conveyance roller pair 8b, the recording paper P passes through the recording unit without causing slack. The speed at which the recording paper P moves in the sub-scanning direction is set to a constant speed.
[0023]
In this way, while moving the recording paper P at a constant speed in the sub-scanning direction, the carriage 2 is moved at a constant speed in the main scanning direction, and the ink ejected from the head 10 is adhered to a predetermined range on one side of the recording paper P. Record an image on
[0024]
FIG. 2 is a block diagram showing an outline of an image data processing circuit in the ink jet printer according to the present embodiment. In the embodiment described below, it is assumed that the nozzles are arranged in the main scanning direction in the order of Y (yellow) M (magenta) C (cyan) K (black) in the head 10. In order to simplify the description, an example including nozzles capable of ejecting four colors of ink has been described, but the present invention is not limited to this.
[0025]
In the processing circuit shown in FIG. 2, each unit is integrally controlled by the CPU 100 via the CPU bus B. In a non-volatile memory (not shown) of the CPU 100, positional deviation data (shift amount from the reference position) for each nozzle measured at the time of manufacturing the ink jet printer is stored for the forward direction and the backward direction in the main scanning direction, respectively. ing. The operation of the ink jet printer will be described. Image data is input to a SCSI circuit 102 via a SCSI connector 101 from a SCSI cable (not shown) connected to an external personal computer or the like.
[0026]
The image data input to the SCSI circuit 102 is further input to the data control unit 103 which is a reading unit, and in accordance with the contents of the distribution control register set in advance by the CPU 100, the composition provided in parallel for each ink color It is input to the drive control units 104Y, 104M, 104C, and 104K as means.
[0027]
On the other hand, in the development memories 105Y, 105M, 105C, and 105K, which are storage means connected to the drive control units 104Y, 104M, 104C, and 104K, the positional deviation data is read from the CPU 100 when the inkjet printer is turned on, for example. The image data, that is, the zero value (hereinafter referred to as correction data) indicating that no ink is ejected by the number corresponding thereto is stored.
[0028]
The drive control units 104Y, 104M, 104C, and 104K combine the correction data before the image data supplied from the data control unit 103, and do not eject any ink after the image data. Data, that is, a zero value (hereinafter referred to as post-data) is added. This point will be described in more detail.
[0029]
FIG. 3A is a diagram schematically showing image data shown in a stored state, and FIG. 3B is a diagram schematically showing image data after being synthesized by the drive control unit. . From the data control unit 103, an image of one row as shown in FIG. 3A (a plurality of rows when nozzles are arranged over a plurality of rows) with respect to the drive control units 104Y, 104M, 104C, and 104K. Data YD, MD, CD, and KD are input. On the other hand, the drive control units 104Y, 104M, 104C, and 104K read the correction data from the corresponding development memories 105Y, 105M, 105C, and 105K and add them to the front of the image data.
[0030]
Here, since the Y-color nozzle is at the head in the forward direction in the main scanning direction, that is, at the front reference position, it is not necessary to add correction data to the front (in this case, meaning to come before the image data in the forward direction). For nozzles of other colors, correction data Msd, Csd, and Ksd, which become longer according to the positional deviation of the nozzles, are added in front of the image data MD, CD, and KD (the left end in FIG. 3B). On the other hand, after the image data YD, MD, and CD (here, meaning that they come after the image data in the forward direction), post-data Yrd, Mrd, and Crd are added. Since the K color nozzle is positioned at the rear reference position when the carriage moves to the rightmost position, it is not necessary to add rear data. The post data consists of the same zero value as that of the correction data, but does not need to correspond exactly to the positional deviation and is used to make the data length constant. Thus, the forward direction composite image data for driving the nozzle is created.
[0031]
Next, creation of backward composite image data will be described. Since the K color nozzle is at the head, that is, the rear reference position in the backward direction in the main scanning direction, it is not necessary to add the correction data to the front (meaning that it comes before the image data in the backward direction). For the nozzles of other colors, the correction data Ysd ′, Msd ′, and Ksd ′, which become longer according to the displacement of the nozzle, are placed before the image data MD, CD, and KD (the right end in FIG. 3B). Append. On the other hand, after the image data MD, CD, and KD (meaning that they come after the image data in the backward direction), post-data Mrd ', Crd', and Krd 'are added. Thus, backward composite image data for driving the nozzles is created.
[0032]
The composite image data formed in this way is converted by the LUT stored in advance, and is input to the p / s circuits 106Y, 106M, 106C, and 106K, respectively, and waits for the timing to be supplied to the nozzles. When the carriage 2, that is, the head 10 starts moving in the forward direction and determines that it has reached the front reference position based on a signal from a sensor (not shown), the CPU 100 drives the I / O control circuit 107, A timing signal is simultaneously transmitted in parallel to the p / s circuits 106Y, 106M, 106C, and 106K via a single wiring w.
[0033]
Then, the p / s circuits 106Y, 106M, 106C, and 106K simultaneously output the composite image data to the nozzles 108Y, 108M, 108C, and 108K. Here, since the correction data is not added to the composite image data output to the Y color nozzle 108Y, the nozzle 108Y immediately starts ink ejection based on the image data YD. However, since the other nozzles are first driven based on the correction data, the head 10 moves in the forward direction while being maintained in a state where ink is not ejected.
[0034]
Thereafter, when the head 10 moves in the forward direction by the positional deviation of the M color nozzle 108M from the previous reference position, the driving based on the correction data Msd is completed, so that the nozzle 108M starts ink ejection based on the image data MD. . Further, when the head 10 moves in the forward direction by the positional deviation of the C-color nozzle 108C from the previous reference position, the driving based on the correction data Csd is completed, so that the nozzle 108C starts ink ejection based on the image data CD. . Further, when the head 10 moves in the forward direction by the positional deviation of the K-color nozzle 108K from the previous reference position, the driving based on the correction data Ksd is completed, so that the nozzle 108K starts ink ejection based on the image data KD. .
[0035]
Thereafter, when ink ejection from the nozzle 108Y based on the image data YD is completed, the nozzle 108Y is maintained in a state where ink is not ejected based on the post-data Yrd. Subsequently, when ink ejection from the nozzle 108M based on the image data MD is completed, the nozzle 108M is maintained in a state where ink is not ejected based on the subsequent data Mrd. Subsequently, when ink ejection from the nozzle 108C based on the image data CD is completed, the nozzle 108C is maintained in a state where ink is not ejected based on the post-data Crd. Finally, when the ink ejection from the nozzle 108K based on the image data KD is completed, the carriage 2 reaches the rear reference position, and then the scanning direction is reversed in the backward direction. Also in the backward direction, nozzle drive control is performed based on the composite image data in the same manner as described above.
[0036]
As described above, according to this embodiment, the wiring w for transmitting the ejection timing signal to the p / s circuits 106Y, 106M, 106C, and 106K is sufficient, and the timing for transmitting from the I / O control unit 107 is sufficient. Only one signal is required per scan, and the control relationship is simplified. Further, since the correction data and the post-data are added to the drive control units 104Y, 104M, 104C, and 104K every time image data is read, it is not necessary to store the composite image data, which contributes to saving of memory capacity.
[0037]
The positional deviation data stored in the nonvolatile memory of the CPU 100 can theoretically store the correction data. However, since the data amount is large, the correction data is 16 bits × It is preferable to store the numerical values n and m after being expressed by n + m because the memory capacity can be saved.
[0038]
FIG. 4 is a diagram showing a data shift when correction data is added. First, consider a case where image data (16 bits) is input to the drive control unit. Here, in order to set the ink ejection position based on the data to an appropriate position, the drive control unit stores in advance that, for example, the image data needs to be shifted by 3 bits and correction data needs to be added thereto. Suppose you are.
[0039]
The drive control unit shifts the image data stored as shown in FIG. 4A backward by 3 bits as shown in FIG. 4B. Then, since the last 3 bits of 16 bits overflow, this is stored in the memory.
[0040]
The image data stored in the memory is read when the next image data is input to the drive control unit (FIG. 3 (c)), and the next image data is shifted backward by 3 bits and synthesized with it. (Fig. 3 (d)). In a similar step, all image data is shifted. This makes it possible to combine with correction data.
[0041]
The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be modified or improved as appropriate.
[0042]
【The invention's effect】
According to the present invention, it is possible to provide an ink jet printer that can easily correct nozzle misalignment by processing data even when an image is formed by ejecting ink from a head during reciprocation.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an example of a mechanical configuration near a head in an ink jet printer according to an embodiment.
FIG. 2 is a block diagram showing an outline of an image data processing circuit in the ink jet printer according to the embodiment.
FIG. 3A is a diagram schematically illustrating image data shown in a stored state, and FIG. 3B is a diagram schematically illustrating image data after being synthesized by a drive control unit. FIG.
FIG. 4 is a diagram showing a data shift according to the present embodiment.
FIG. 5 is a diagram schematically showing the arrangement of nozzle rows arranged in a head.
FIG. 6 is a diagram illustrating a discharge start signal of each nozzle row.
[Explanation of symbols]
2 Carriage 5 Flexible cable 6 Carriage drive mechanism 10 Head 100 CPU
103 Data control unit 104Y, 104M, 104C, 104K Drive control unit 105Y, 105M, 105C, 105K Development memory 106Y, 106M, 106C, 106K p / s circuit 108Y, 108M, 108C, 108K Nozzle

Claims (4)

In an inkjet printer having a plurality of nozzles capable of ejecting ink based on image data arranged in the main scanning direction and having a head movable in the main scanning direction,
Storage means for storing correction data corresponding to the positional deviation of each nozzle;
Reading means for reading image data;
A plurality of combining means provided for each nozzle of a plurality of nozzles arranged in the main scanning direction for combining the read image data and the correction data;
CPU for controlling the timing of outputting the correction data combined with the image data by the combining means to each nozzle ,
The correction data is 16 × n + m numerical values n and m (both integers greater than or equal to 0), where the input unit of image data read from the reading unit and input to each of the combining units at a time is 16 bits. ) Is stored, and is data for moving the head in the main scanning direction in a state where ink is not ejected from the nozzles.
The composition of the image data and the correction data by the combining means is performed at the timing of inputting the image data from the reading means based on the stored n and m values of the correction data with respect to the moving direction of the head. In this case, the n + 1th image data input from the reading means is shifted backward by m bits with respect to the moving direction of the head, and correction data is forwardly generated. The overflowing m-bit image data is created by adding the n + 2th input image data to the front after shifting the overflowing m-bit backward image data.
The combined correction data is output by the CPU at a common timing to each nozzle. 2. The ink jet printer according to claim 1, wherein the nozzles of the head eject ink based on the synthesized image data in both directions in the main scanning direction. The ink jet printer according to claim 1, wherein post data for preventing ink from being ejected from the nozzles is added after the image data with respect to the moving direction of the head. 4. An ink jet printer according to claim 1, wherein nozzles capable of discharging a plurality of colors of ink are arranged in the main scanning direction.

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