JP2002113849A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink jet printer which can vary the resolution by inclining the direction of a nozzle array and can form an image at an appropriate position on a recording sheet. SOLUTION: A dot pitch in the sub-scanning direction is calculated so that all dots in the sub-scanning direction of image data on one page of a received recording sheet can be located on one sheet of recording medium. An ink head 52 is turned in the ink head insertion hole 53 of an ink carriage 51 such that a nozzle array has an inclination angle at which the calculated dot pitch can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer which forms an image by ejecting ink droplets on a recording medium (recording paper). In particular, the present invention relates to an improvement in an image forming operation in an ink jet printer that changes the resolution of an image.

[0002]

2. Description of the Related Art In general, an ink-jet type image forming apparatus (hereinafter, referred to as an ink-jet printer) is an ink-jet image forming apparatus which is capable of reciprocating in a direction (main scanning direction) orthogonal to a recording paper conveyance direction (sub-scanning direction). A carriage is provided, and an ink head is mounted on the ink carriage. Then, ink droplets are ejected from each nozzle of the ink head toward the recording paper while the operation of transporting the recording paper in the sub-scanning direction and the operation of moving the ink carriage in the main scanning direction are performed alternately. A predetermined image is formed thereon.

In this type of ink jet printer, as an image forming operation, an image forming mode (speed printing mode) in which the image forming speed is prioritized over the image resolution, and the image resolution is higher than the image forming speed. There is an image forming mode (high image quality mode) in which is given priority. Japanese Patent Laid-Open Publication No. Hei.
There is an ink jet printer disclosed in Japanese Patent Publication No. 1-235813. In this publication, as an ink head mounted on an ink carriage, a plurality of types of ink heads capable of forming images at mutually different resolutions are prepared, and the ink heads can be replaced according to a required image forming mode. The technical idea described above is disclosed.

However, in the ink jet printer disclosed in this publication, it is necessary to replace the ink head in accordance with the required resolution, and the burden on the user is large. Further, since it is necessary to prepare a plurality of types of ink heads, it is necessary to secure a storage place for unused ink heads and manage the storage state thereof, which also increases the burden on the user,
It also led to soaring costs.

As means for solving these problems, it is conceivable that the direction of the nozzle row of the ink head can be inclined with respect to the sub-scanning direction, thereby making the pitch of each nozzle in the sub-scanning direction variable. (This kind of technical idea is disclosed in, for example, JP-A-3-290263 and JP-A-5-96728). For example, if the direction of the nozzle row is inclined by 60 ° with respect to the sub-scanning direction, it is possible to obtain twice the resolution as compared with the case where the direction of the nozzle row is matched with the sub-scanning direction. Without changing the resolution, it is possible to form an image in a desired image forming mode by changing the resolution.

[0006]

However, in the case where the resolution is variable by inclining the direction of the nozzle row, the inclination angle of the nozzle row is independent of the amount of image data per recording sheet. Is set, for example, a part of the image G protrudes from the sheet P as shown in FIG. 13A, or the image G is biased to one side of the sheet P as shown in FIG. It may be formed. Note that the image forming area G in each of these figures is a portion surrounded by a broken line.

The inventor of the present invention sets the inclination angle of the nozzle row appropriately in accordance with the image data in order to realize a configuration in which the resolution is variable by inclining the direction of the nozzle row as described above. The present invention has been achieved by focusing on the fact that the image forming position must be set to a predetermined position (for example, substantially the center position of the recording paper).

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ink jet printer in which the resolution is variable by inclining the direction of a nozzle row, so that an ink jet printer suitable for recording on a recording paper can be used. An object of the present invention is to enable image formation at a position.

The inventor of the present invention has also paid attention to the fact that when image formation is performed using image data in which text data and image data are mixed, the resolution required for each data is different. Specifically, a relatively low resolution is required for image formation based on text data, but a high resolution is required for image formation based on image data. The inventor of the present invention has also studied to enable an image forming operation that satisfies each requirement.

Another object of the present invention is to realize an appropriate image forming operation for image data in which text data and image data are mixed, according to each data.

[0011]

Means for Solving the Problems-Summary of the Invention-In order to achieve the above object, the present invention sets the inclination angle of a nozzle row according to image data, that is, converts the resolution of an image to image data. By setting according to this, an image is formed at a predetermined position on a recording medium (recording paper).

-Solution Means- More specifically, it is assumed that an ink jet printer is provided with a nozzle row tilting mechanism that can tilt the direction of the nozzle row with respect to the transport direction of the recording medium. A data receiving unit that receives image data for the inkjet printer;
Angle setting means. The angle setting means calculates a dot pitch in the sub-scanning direction in which all of the dots in the sub-scanning direction based on the image data for one page of the recording medium received by the data receiving means can be located on one recording medium. The nozzle array tilting mechanism is controlled so that the nozzle array has an inclination angle at which the dot pitch is obtained.

According to this specific matter, the angle setting means controls the nozzle row tilt mechanism to set the tilt angle of the nozzle row to a predetermined angle based on the image data received by the data receiving means. The nozzle row inclination angle is set so as to obtain a dot pitch in the sub-scanning direction that enables all dots in the sub-scanning direction based on image data for one page of the recording medium to be located on one recording medium. . For this reason, the problem that a part of the image protrudes in the sub-scanning direction of the recording medium is solved.

Further, another invention has the following configuration. That is, a data receiving unit for receiving image data and a resolution setting unit are provided. The resolution setting means determines the data content of the image data received by the data receiving means, selects a required resolution according to the data content, and sets the nozzle row to an inclination angle at which the required resolution is obtained. In addition, it controls the nozzle row tilting mechanism.

According to this specific matter, based on the image data received by the data receiving means, the resolution setting means controls the nozzle row tilt mechanism to set the tilt angle of the nozzle row to a predetermined angle. The nozzle row inclination angle is set such that the required resolution according to the data content is obtained. Therefore, even when multiple types of image data such as text data and image data are received at the same time,
An image can be formed at an appropriate resolution according to each data.

The following is a specific configuration in which the resolution in the main scanning direction is made variable by image data. That is, by adjusting the ejection timing of ink droplets from each nozzle according to the nozzle row inclination angle, all dots in the main scanning direction based on image data for one page of the recording medium are located on one recording medium. The resolution in the main scanning direction is adjusted so that

According to this specific matter, the problem that a part of the image runs off in the main scanning direction of the recording medium is solved, and the image can be formed at a predetermined position on the recording medium.

Further, the nozzle row tilt mechanism is configured to change the nozzle row tilt angle by rotating the ink head with respect to the ink carriage, and the ink carriage displays the rotation position of the ink head with respect to the ink carriage. When an index is provided, the user can confirm the current resolution by viewing the index. That is, it is possible to check the resolution without requiring any special resolution detecting means (a sensor for detecting the rotational position of the ink head) or a resolution displaying means (such as a liquid crystal display unit for displaying the resolution). it can.

Further, as a configuration in a case where the above-mentioned nozzle row tilting mechanism is applied to a color ink jet printer, the following can be mentioned. That is, by providing a plurality of ink heads corresponding to the inks of a plurality of colors, the nozzle array tilting mechanism connects the ink heads to each other and synchronizes the respective ink heads to set the same tilt angle, thereby providing a nozzle array for each color. Are made to have the same inclination angle.

According to this specific matter, the resolution of image formation by the ink head corresponding to each color matches, and a color image can be formed at a predetermined position on a recording medium.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) -Description of Configuration of Inkjet Printer- First, the configuration of an inkjet printer 1 according to the present embodiment will be described with reference to FIGS.
FIG. 1 is a perspective view showing the appearance of the ink jet printer 1. FIG. 2 is a schematic diagram showing the internal structure of the ink jet printer 1.

In the ink jet printer 1, a paper feed cassette 3 is provided on the front side (the right side in FIG. 2) of the cabinet 2, and a paper discharge tray 4 is provided above the paper feed cassette 3 on the front side. Have been.

On the other hand, as shown in FIG.
, A pickup roller (not shown), a feed roller 11,
A transport roller pair 12, a PS roller (not shown), an ink jet mechanism 5, and a paper discharge roller pair 15 are sequentially provided.

The ink-jet mechanism 5 includes an ink carriage holding shaft (not shown) extending in a direction perpendicular to the plane of FIG. 2, an ink carriage 51 (see FIG. 3) held by the ink carriage holding shaft, An ink head 52 that is reciprocally scanned (reciprocated in the left-right direction in FIG. 3) together with the ink carriage 51 along the ink carriage holding shaft.
An ink tank (not shown) is mounted on the ink carriage 51.

Hereinafter, the detailed configurations of the ink carriage 51 and the ink head 52 will be described. The ink carriage 51 is shown in FIG. 3 (a plan view of the ink carriage 51 and the ink head 52) and FIG. 4 (IV-IV in FIG. 3B).
As shown in the sectional view taken along the line), an ink head insertion hole 53 is formed in the center. The ink head insertion hole 53 has a central hole 53a located at the center in the vertical direction in FIG. 4, and position regulating holes 53b and 53c formed continuously above and below the central hole 53a. It has. The central hole 53a is formed of a columnar space. The position regulating holes 53b and 53c are formed as cylindrical spaces slightly smaller in diameter than the central hole 53a, and as shown in FIG. Convex portions 53d, 53 for regulating the movement position
d is formed.

A pulse motor 54 is provided on one side (the right end in FIG. 3) of the ink carriage 51. A relatively small gear 54b is provided at the upper end of a drive shaft 54a of the motor 54. It is attached to the rotating body.

On the other hand, as shown in FIG. 3, the ink head 52 is rotatably inserted within a predetermined rotation angle range inside the ink head insertion hole 53. Specifically, the central portion in the height direction of the ink head 52 is
The guide hole 52a is formed on a guide portion 52a having an outer peripheral surface that matches the curvature of the inner peripheral surface of the central hole portion 53a.
Regulators 52b and 52c having outer peripheral surfaces that match the curvatures of the inner peripheral surfaces of b and 53c are formed. Further, the upper regulating portion 52b is provided with a projecting portion 52d projecting outward from the inner peripheral surface of the position regulating hole 53b, and the outer periphery of the projecting portion 52d is formed in an arc shape. A gear portion 52e meshing with the gear 54b is formed on the periphery. That is, the rotation of the gear 54b with the driving of the motor 54 transmits the rotation force to the ink head 52 via the gear portion 52e, and the ink head 52 rotates in the ink head insertion hole 53. It has become. The rotation angle of the ink head 52 can be set arbitrarily by adjusting the rotation amount of the motor 54. Thus, the nozzle row tilting mechanism 5A according to the present invention is configured.

For example, the state shown in FIG. 3 (a) shows a posture in which the ink head 52 has been turned clockwise in FIG. 3 (the rotation angle of the ink head 52 is 0 °).
In this state, the position is regulated by the side surface of the ink head 52 abutting on the protrusions 53d of the ink head insertion hole 53. The state shown in FIG. 3B is a posture in which the ink head 52 has been rotated by 60 ° counterclockwise in the figure from the state of FIG. 3A (the rotation angle of the ink head 52 is 60 °). Is shown.

The ink head 52 has a plurality of nozzles 5
5, 55,... Are formed. These nozzles 55, 5
Are arranged in a straight line in the longitudinal direction of the ink head 52 (vertical direction in FIG. 3A) to form a nozzle row. Are connected to the ink tank via a supply path (not shown) so that ink is supplied from the ink tank. Then, the ink head 52 shown in FIG.
In the rotational position of, the direction of the nozzle row is the vertical direction in the figure (the transport direction of the recording paper: the sub-scanning direction). On the other hand, at the rotational position of the ink head 52 shown in FIG. 3B, the direction of the nozzle row is inclined by 60 ° with respect to the transport direction of the recording paper.

FIG. 5 is a block diagram showing the configuration of the control unit 6 of the ink jet printer 1. As shown in FIG. Hereinafter, the configuration of the control unit 6 will be described. As shown in FIG. 5, the control unit 6 includes an interface 61 as data receiving means for receiving image data from a data source such as a personal computer, an interface memory 62 for storing the received image data, The print memory 63 receives image data from the interface memory 62 at the time of printing). The image data is transmitted from the print memory 63 as appropriate, and the ink jet mechanism 5 is controlled based on the print data so that the ink from each of the nozzles 55, 55,. A print head driver 64 for controlling the timing of discharging droplets is provided. The control operation of the interface 61, the interface memory 62 and the print memory 63, and the driving operation of the motor 54 are performed by a CPU.
65.

The control section 6 of this embodiment is provided with a resolution calculation ROM 66 as angle setting means. The resolution calculation ROM 66 calculates the resolution required for image formation based on the image data for each page stored in the interface memory 62, and stores an image formed by the image data for one page as a recording medium. Recording paper P
An arithmetic program for automatically adjusting the rotation angle of the ink head 52 and automatically setting the inclination angle of the nozzle row is stored so as to be formed within the range of one sheet. That is, the dot pitch in the sub-scanning direction in which all the dots in the sub-scanning direction based on the received image data for one page of the recording sheet can be located on one recording sheet is calculated. The rotation angle of the ink head 52 is adjusted so that the obtained inclination angle is obtained.

The setting operation of the rotation angle of the ink head 52 by the calculation program of the resolution calculation ROM 66 will be specifically described below. For example, when the direction of the nozzle row coincides with the sub-scanning direction (the state shown in FIG. 3A)
When the print resolution is 600 dpi (FIG. 6)
(A), 1200 dots per inch (120 dots) in the sub-scanning direction in order to print the image data per page received by the interface 61 on one sheet of recording paper P.
When 0 dpi) is required, the rotation angle of the ink head 52 (the inclination angle of the nozzle row) is calculated to be 60 ° from the following equation.

Rotation angle = COS ⁻¹ (600/1200) /
(2 × π) × 360 = 60 As a result, the inclination angle of the nozzle row is set to 60 ° as shown in FIG.
Pi can be used for image formation.

Similarly, when the print resolution is 600 dpi when the direction of the nozzle row coincides with the sub-scanning direction (see FIG. 7A), the interface 6
1 prints the image data per page received on one recording paper P in the sub-scanning direction.
When 00 dots (2400 dpi) are required, the rotation angle of the ink head 52 (the inclination angle of the nozzle row) is calculated to be 75.52 ° from the following equation.

Rotation angle = COS ⁻¹ (600/2400) /
(2 × π) × 360 = 75.52 As a result, the inclination angle of the nozzle row is set to 75.52 ° as shown in FIG.
Image formation at 00 dpi becomes possible.

Further, the calculation program in the resolution calculation ROM 66 prints all the dots in the paper width direction of the image data of each page within the width of one recording paper P in the main scanning direction. The dot pitch in the main scanning direction is calculated so that the movement pitch of the ink carriage 51 (movement pitch in the main scanning direction) can be controlled.

Thus, all the images based on the image data for one page can be formed on one recording sheet P in conformity with the sheet size.

-Explanation of Printing Operation- When the printing operation of the ink jet printer 1 is started, first, one of the recording papers P stored in the paper feed cassette 3 is taken out by a pickup roller, and is fed to a feeding roller. It is conveyed by 11 and a conveying roller pair 12.
Then, the recording paper P is conveyed to the image forming position 16 facing the ink head 52 with the leading end of the recording paper P aligned with the image information by the PS roller. When the recording paper P passes through the image forming position 16, ink droplets are individually ejected from each of the nozzles 55 provided on the ink head 52 based on the position of the recording paper P and the image data. Thus, an image is formed on the upper surface of the recording paper P (the details of the ink droplet ejection operation will be described later).

The image forming operation will be specifically described.
When the recording paper P is transported to the image forming position 16, the ink carriage 51 moves from the nozzles 55 to the recording paper P while moving in the direction of arrow I (main scanning direction) in FIG. Ink is ejected, and an image is formed on the recording paper P by this. Ink carriage 5
When the recording paper P moves to one end of the recording paper P, the recording paper P is moved (conveyed) by a predetermined amount (arrow II in FIG. 3A).
After moving in the sub-scanning direction indicated by I), the operation is stopped. Then, image formation is performed while the ink carriage 51 moves in the direction of arrow II (main scanning direction) in FIG. In this manner, the image forming operation by the reciprocating movement of the ink carriage 51 and the feeding operation of the recording paper P are performed alternately, and the image is formed on the entire recording paper P.

The recording paper P on which an image is formed over substantially the entire surface is discharged toward the discharge tray 4 by a pair of discharge rollers 15. As a result, the recording paper P on which a predetermined image has been formed is discharged to the discharge tray 4 in a face-up state (a state in which the image forming surface faces upward).

Next, the operation of discharging ink droplets, which is a feature of this printing operation, will be described with reference to the flowchart of FIG.

In the ink droplet ejection operation, first, in step ST1, one page of image data is received by the interface 61, and the image data is stored in the interface memory 62. In step ST2, the inclination angle of the nozzle row in accordance with the resolution of the recording paper P in the feed direction (sub-scanning direction) so that all the images based on the image data for one page can be formed on one recording paper P. But,
It is calculated by a calculation program stored in the resolution calculation ROM 66. Thereafter, in step ST3, the motor 5 is driven so that the calculated inclination angle of the nozzle row is obtained.
4 to drive the ink head 52 into the ink head insertion hole 5.
Rotate within 3. That is, as described above, 1200d
When a resolution of pi is required, the inclination angle of the nozzle row is 6
When the resolution is set to 0 ° and a resolution of 2400 dpi is required, the motor 54 is driven to rotate the ink head 52 so that the inclination angle of the nozzle row is set to 75.52 °.

With the ink head 52 thus rotated, the resolution in the main scanning direction is calculated based on the rotation angle of the ink head 52 in step ST4. In step ST5, the ejection timing of the ink droplet is set in accordance with the calculated resolution in the main scanning direction. In other words, all the dots in the paper width direction of the image data can be printed within the width of one recording paper P.
The dot pitch in the main scanning direction is calculated, the movement pitch of the ink carriage 51 is controlled, and the ejection timing of the ink droplet is set.

At the time of discharging ink droplets, first, in step ST6, a line counter N previously set in the CPU 65 is set to 1. That is, since image formation is performed sequentially from the first line (the first line on the leading side in the transport direction of the recording paper P), the line counter N is set to 1. Thereafter, in step ST7, the image data of the first line is transmitted from the interface memory 62 to the print head driver 64 via the print memory 63, and the ejection operation of the ink droplet is performed at the set ejection timing. A predetermined image formation (first line image formation) is performed.

After the image formation of the first line is performed in this way, in step ST8, it is determined whether or not the line on which the image formation is completed is the last line of one page. If it is determined that the last row has not been reached (NO), the process proceeds to step ST9, where "1" is added to the count value N of the line counter (N = N + 1), and step ST9 is performed.
Return to 7. In this manner, image formation is performed from the first line to the last line of one recording sheet P while sequentially adding “1” to the count value N of the line counter. When the image formation of the last line is completed, YES is determined in step ST8, and the image forming operation for one recording sheet P is completed.

When the interface 61 receives image data of a plurality of pages, such an operation is performed for each image data of each page, and an image is formed by each image data on each recording paper P. Done.

As described above, in this embodiment, the rotation of the ink head 52 is performed so that an image formed by one page of image data can be formed within the range of one recording sheet P. By adjusting the angle, the inclination angle of the nozzle row is automatically set. For this reason, the problem that a part of the image runs off the recording paper P is solved, and the image can be formed at an appropriate position on the recording paper P.

(Second Embodiment) Next, a second embodiment will be described. This embodiment is a modification of the rotation operation of the ink head 52, and the other configuration is the same as that of the above-described first embodiment. Therefore, here, the ink head 5
Only the configuration of the control unit 6 for performing the rotation operation 2 and the image forming operation will be described.

FIG. 9 is a block diagram showing the configuration of the control unit 6 of the ink jet printer 1 according to this embodiment. The control unit 6 includes a text / image mixed print control ROM 67 as resolution setting means instead of the resolution calculation ROM 66 in the control unit 6 of the inkjet printer 1 according to the first embodiment described above. The text / image mixed print control ROM 67 stores an arithmetic program for determining whether the data is text data or image data for each dot of the image data, and changing the rotation angle of the ink head 52 accordingly. ing. That is, if the text data does not require a high resolution, the rotation angle of the ink head 52 is set small, and if the image data requires a high resolution, the rotation of the ink head 52 is reduced. The motor 54 is controlled so that the moving angle is set large.

Next, the operation of ejecting ink droplets in this embodiment will be described with reference to the flowchart of FIG.

In the ink droplet ejection operation, first, in step ST11, the image data for one page is received by the interface 61, and the image data is stored in the interface memory 62. In step ST12, the magnification in the main scanning direction and the sub-scanning direction is calculated so that all the images based on the image data for one page can be formed on one recording sheet P.

Then, in step ST13, the line counter N is set to 1. That is, since image formation is performed sequentially from the first line (the first line on the leading side in the transport direction of the recording paper P), the line counter N is set to 1. In step ST14, the print position counter M is set to 1. That is, since image formation is performed sequentially from the head of the line, the print position counter M is set to 1
Set to.

Next, in step ST15, the M-th image data of the N-th row (the first image data of the first row at the start of the image forming operation) is taken out from the interface memory 62, and this image data is the image data. It is determined whether or not there is. If the image data is image data, the process proceeds to the control operation from step ST16. On the other hand, if the image data is text data, the process proceeds to step ST20.
Move to the subsequent control operation.

In step ST16 when the image data is image data, the resolution required for forming an image based on the image data and the above-mentioned step ST1 are determined.
The motor 54 is controlled to rotate the ink head 52 so as to incline the nozzle row at an inclination angle suitable for the magnification in the sub-scanning direction calculated in Step 2. Step ST1
In step 7, the resolution in the main scanning direction is calculated from the rotation angle of the ink head 52. In step ST18, the calculated resolution in the main scanning direction is compared with the resolution in step ST12.
The ejection timing of the ink droplets is set so as to conform to the magnification in the main scanning direction calculated in step (1).

After the inclination angle of the ink head 52 and the ejection timing of ink droplets are set in this way, in step ST19, image data is transmitted from the interface memory 62 to the print head driver 64 via the print memory 63, An ink droplet ejection operation is performed at the set ejection timing, whereby a predetermined image is formed on the recording paper P (image formation based on the Mth image data (image data) in the Nth row).

In step ST20 where the image data is text data, the motor 54 is controlled to incline the ink head 52 at an inclination angle suitable for the magnification in the sub-scanning direction calculated in step ST12. 52 is rotated. In step ST21, the resolution in the main scanning direction is calculated from the rotation angle of the ink head 52. In step ST22, the ejection timing of the ink droplets is set to match the calculated resolution in the main scanning direction and the magnification in the main scanning direction calculated in step ST12.

After the inclination angle of the ink head 52 and the ejection timing of ink droplets are set in this way, in step ST23, text data is transmitted from the interface memory 62 to the print head driver 64 via the print memory 63, An ink droplet ejection operation is performed at the set ejection timing, whereby a predetermined image is formed on the recording paper P (image formation based on the Mth image data (text data) on the Nth line).

After the image formation based on the M-th image data in the N-th row has been performed in this way, step ST2
In 4, it is determined whether or not the M-th image for which image formation has been completed is the last image data of the line. And
If it is determined that the image data has not reached the last image data of the line, the process proceeds to step ST25, where "1" is added to the count value M of the print position counter (M = M +
1) Return to step ST15. In this way, while adding “1” to the count value M of the print position counter in order, image formation is performed from the head position to the end position of the line. When the image formation based on the last image data of the line is completed, Y is determined in step ST24.
The determination is ES, and the process proceeds to step ST26.

In step ST26, it is determined whether or not the line on which image formation has been completed is the last line of one page.
If it is determined that the last row has not been reached (NO), the process proceeds to step ST27, where "1" is added to the count value N of the line counter (N = N + 1), and step S27 is performed.
Return to T14. In this manner, image formation is performed from the first line to the last line while sequentially adding “1” to the count value N of the line counter. When the image formation of the last line is completed, step S
YES is determined in T26, and the image forming operation on one recording sheet P ends.

In this way, the required resolution is selected according to the data content (whether it is image data or text data) of the image data at each position in each row,
The image formation is performed while appropriately changing the inclination angle of the ink head 52 so that the nozzle row has the inclination angle at which the required resolution is obtained. And the interface 61
Is received for a plurality of pages of image data, such an operation is performed for each page of image data, and an image is formed on each recording sheet P by each image data.

As described above, in this embodiment, the inclination angle of the ink head 52 (the inclination angle of the nozzle array) is changed according to whether the image data is image data or text data. An image is formed. Therefore, even when a plurality of types of image data are received at the same time, it is possible to form an image with an appropriate resolution according to each data.

(Modifications) Next, modifications of the above embodiments will be described.

First, as a first modified example, a configuration provided with an index for displaying the rotational position of the ink head 52 with respect to the ink carriage 51 will be described.

As shown in FIG. 11, on the upper surface of the ink carriage 51 in this example, an index 7 indicating a resolution set according to the rotational position of the ink head 52 is drawn. In the case of FIG. 11, “300 dpi”, “400 dpi”, “500 dpi” according to the rotational position of the ink head 52.
dpi, "600 dpi", "900 dpi", "1
200 dpi "," 2400 dpi "," 4800 dpi "
Each index 7 of "i" is drawn. On the other hand, the ink head 5
On the upper surface of 2, a triangular mark 71 for indicating each index 7 is drawn, and according to the rotation position of the ink head 52, the mark 71 indicates a specific index 7 so that the user can You can see the current resolution.
Note that FIG. 11A shows a state in which the rotation angle of the ink head 52 is 0 ° and the mark 71 points to the index 7 of “300 dpi”, and FIG. When the rotation angle is 60 ° and the mark 71 is “60”
0 dpi ”is indicated.

As the image forming operation in this example, any of the above-described operations in the first embodiment and the operations in the second embodiment can be adopted.

As described above, according to this embodiment, special resolution detecting means (a sensor for detecting the rotational position of the ink head) and resolution displaying means (such as a liquid crystal display for displaying a resolution) are required. It is possible to check the resolution without doing so.

Hereinafter, a second modified example will be described. This example is a case where the present invention is applied to a color inkjet printer. The color inkjet printer according to the present embodiment includes a plurality of ink heads 81, 82, 83, and 84 corresponding to respective colors of Y (yellow), M (magenta), C (cyan), and Bk (black). The nozzles 55 formed in these ink heads 81 to 84,
At 55,..., Ink tanks (not shown) storing the inks of the respective colors are individually connected via supply paths.

In this embodiment, the ink heads 81 to 84 are connected to each other by two connecting rods 85, 85 and are configured to rotate in synchronization. Specifically, the black ink head 84 located on the rightmost side in FIG. 12 includes an overhang portion 84a, and the outer periphery of the overhang portion 84a is formed in an arc shape. A gear portion 84b that meshes with the rotating gear 54b is formed. That is, when the gear 54b rotates with the driving of the motor 54, the rotational force is transmitted to the black ink head 84 via the gear portion 84b, and the rotational power of the black ink head 84 is transmitted by the connecting rods 85, 85. It is transmitted to the other ink heads 81 to 83, whereby each of the ink heads 81 to 84 is synchronously rotated within the ink head insertion hole 53 by the same rotation angle. For example, FIG.
The state shown in FIG. 2A shows a posture in which each of the ink heads 81 to 84 is rotated clockwise in the drawing most (a state where the rotation angle of each of the ink heads 81 to 84 is 0 °). In addition, the state shown in FIG.
Reference numeral 84 denotes a posture rotated by 30 ° in the counterclockwise direction from the state of FIG. 12A (a state in which the rotation angles of the ink heads 81 to 84 are 30 °).

As the image forming operation in this example, any of the above-described operations in the first embodiment and the operations in the second embodiment can be adopted.

As described above, in this example, a color image can be formed at a predetermined position on the recording paper P.

In this example, the four color ink heads 8 are used.
Although the case where 1 to 84 are provided has been described, the present invention is not limited to this.

-Other Embodiments- In each of the above embodiments and modifications, the ink head 5
The case where only one nozzle row is formed in 2, 81 to 84 has been described. The present invention is not limited to this, and is also applicable to an ink jet printer having an ink head having a plurality of nozzle rows.

Further, by combining the present invention with a device that makes the size of the ink droplet ejected from each nozzle variable (a device that performs a so-called drop modulation), it is possible to realize higher image quality.

[0075]

As described above, according to the present invention, the recording medium 1
All dots in the sub-scanning direction based on image data for one page
The nozzle row inclination angle is set so as to obtain a dot pitch in the sub-scanning direction that can be positioned on one recording medium. For this reason, the problem that a part of the image protrudes in the sub-scanning direction of the recording medium is solved. As a result, an image can be formed at an appropriate position on the recording medium, and the reliability of the image forming operation can be improved. Further, it is not necessary to transmit a control command relating to the nozzle array tilt angle from a source of image data such as a personal computer, or to perform a switch operation for setting the nozzle array tilt angle on the inkjet printer side. Therefore, an image can be formed at an appropriate resolution without any special consideration by the user.

When the nozzle row inclination angle is set so as to obtain the required resolution according to the data content, even if a plurality of types of image data such as text data and image data are received at the same time, An image can be formed at an appropriate resolution according to each data, and the quality of the entire image formed on the recording medium can be improved. Further, when image formation is performed at the same resolution on the entire recording medium as in the related art, if text data and image data are mixed, image formation is performed at a high resolution on the entire recording medium. However, since the image formation of the text data portion is performed at a high resolution, the image forming time is prolonged, and the ink consumption increases more than necessary. Further, if an image is formed at a low resolution on the entire recording medium, a sufficient image quality cannot be obtained in the image data portion. In the present invention, since the resolution can be changed according to each image data, the image forming time can be reduced, the ink consumption can be reduced, and the image quality can be improved.

Further, in addition to the above invention, the resolution in the main scanning direction is adjusted so that all dots in the main scanning direction based on image data of one page of the recording medium can be located on one recording medium. In this case, the problem that a part of the image runs off in the main scanning direction of the recording medium can be solved, and the image can be formed at a predetermined position on the recording medium. Can be further improved.

Further, when an index for indicating the rotational position of the ink head with respect to the ink carriage is provided, the user can confirm the current resolution by visually checking the index. As a result, the resolution can be checked without requiring any special means, and the cost can be reduced.

In addition, when a plurality of ink heads corresponding to a plurality of color inks are provided, and the respective ink heads are connected to each other and set at the same inclination angle in synchronization with each other, the ink heads corresponding to the respective colors are used. The resolution of image formation by the ink heads thus matched is matched, and a color image can be formed at a predetermined position on the recording medium.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an appearance of an inkjet printer according to an embodiment.

FIG. 2 is a schematic diagram showing an internal structure of the ink jet printer.

FIG. 3 is a plan view illustrating an ink carriage and an ink head according to the first embodiment.

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3 (b).

FIG. 5 is a block diagram illustrating a configuration of a control unit according to the first embodiment.

FIG. 6A shows the dot pitch in the sub-scanning direction when the nozzle row tilt angle is 0 °, and FIG. 6B shows the dot pitch in the sub-scanning direction when the nozzle row tilt angle is 60 °. FIG.

7A shows a dot pitch in the sub-scanning direction when the inclination angle of the nozzle row is 0 °, and FIG. 7B shows a dot pitch in the sub-scanning direction when the inclination angle of the nozzle row is 75.52 °. It is a figure showing a pitch.

FIG. 8 is a flowchart of an ink droplet ejection operation in the first embodiment.

FIG. 9 is a diagram corresponding to FIG. 5 in the second embodiment.

FIG. 10 is a diagram corresponding to FIG. 8 in a second embodiment.

FIG. 11 is a diagram corresponding to FIG. 3 in a first modified example.

FIG. 12 is a diagram corresponding to FIG. 3 in a second modified example.

FIG. 13 is a diagram illustrating a relationship between a sheet and an image forming area for explaining a conventional problem.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Ink jet printer 51 Ink carriage 52, 81-84 Ink head 55 Nozzle 5A Nozzle array inclination mechanism 61 Interface (data receiving means) 66 Resolution calculation ROM (Angle setting means) 67 Text / image mixed print control ROM (Resolution setting means) 7 Index P Recording paper (recording medium)

Claims (5)

[Claims] 1. An ink jet printer having a nozzle array tilting mechanism capable of tilting the direction of a nozzle array with respect to the transport direction of a recording medium, a data receiving means for receiving image data, and a data receiving means for receiving the image data. A dot pitch in the sub-scanning direction that allows all of the dots in the sub-scanning direction based on the image data for one page of the recording medium to be located on one recording medium is calculated. An ink jet printer comprising: an angle setting unit that controls the nozzle row tilting mechanism so as to obtain a tilt angle. 2. An ink jet printer having a nozzle array tilting mechanism capable of tilting the direction of a nozzle array with respect to the transport direction of a recording medium, a data receiving means for receiving image data, and a data receiving means for receiving the image data. A resolution setting for controlling the nozzle row tilt mechanism so as to determine the data content of the image data obtained, select a required resolution according to the data content, and control the nozzle row tilt mechanism so that the nozzle row has a tilt angle at which the required resolution is obtained. And an ink jet printer. 3. The ink jet printer according to claim 1, wherein the ejection timing of the ink droplets from each nozzle is adjusted in accordance with the nozzle row inclination angle, and the ejection timing in the main scanning direction based on the image data of one page of the recording medium. An ink jet printer, wherein the resolution in the main scanning direction is adjusted so that all of the dots can be located on one recording medium. 4. The ink jet printer according to claim 1, wherein the nozzle row tilt mechanism changes the nozzle row tilt angle by rotating the ink head with respect to the ink carriage. An ink jet printer, wherein the ink carriage is provided with an index for indicating a rotation position of the ink head with respect to the ink carriage. 5. The ink jet printer according to claim 1, further comprising: a plurality of ink heads corresponding to a plurality of color inks; By connecting and synchronizing and setting the same inclination angle,
An ink jet printer, wherein the inclination angle of a nozzle row for each color is made to match.