JPH11334046A - Method for printing in medium coverage area with ink jet nozzle array - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a hysteresis under load by printing an ink along a spiral track route and make it possible to perform an ink jet printing in a unidirection so that an unprinted blank area is eliminated when drawing a luster sweep on a flat medium using an ink jet nozzle array. SOLUTION: In an ink jet printing system 50, an ink jet nozzle array is arranged and a flat medium 10 is supported in such a way that ink droplets ejected from the nozzle array during an ink jet printing cycle are received. In addition, the ink droplets are ejected onto the medium 10 during the ink jet printing cycle. In this case, a relative movement is set between the nozzle array and the medium 10 in such a manner that during the ink jet printing cycle, the nozzle array defines a spiral track with the medium 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for printing on an area of a medium by an ink jet nozzle array, which prints on the medium by an ink jet.
More specifically, with regard to coverage with an ink jet nozzle array and its ink jet printing system, printing is performed along a spiral trajectory path to reduce mechanical hysteresis and eliminate unprinted margins. TECHNICAL FIELD The present invention relates to a method of printing on a region of a medium by an inkjet nozzle array that performs inkjet printing in one direction and an inkjet printing system thereof.

[0002]

Conventionally, in this type of ink-jet printing, a row of nozzles moves the surface of a flat, rectangular medium, usually from left to right, then back from right to left, and It is well known to arrange (drop) ink droplets on a medium by means of a square raster sweep that moves from top to bottom. In this manner, a row of inkjet nozzles may move through the entire area of the medium one or more times, depending on the length of vertical movement, the length of left and right scans, and the offset of the start of the sweep. .

[0003] During raster sweeping, ink jet nozzles are driven in response to data to fire (eject) ink droplets, which deposit on the media to form text or images on the media. Is done. This process introduces some undesirable errors. This error is generally caused by the angle at which the droplet is ejected from the nozzle, the timing resolution, the position error of the ink jet head mounting caused by position detection and significant mechanical hysteresis, ie, mechanical alignment.

Hysteresis moves from left to right,
This is caused by a non-repeatable position trace while moving from left to right. As a result, the command position becomes incorrect, and the ink ejection from the nozzle position is shifted. Hysteresis is often
It is caused by the friction of the mechanism due to the normal tolerances of the assembly and is pronounced by the start-stop movement of the mechanism. The static friction force may be larger than the dynamic friction force. This static friction force tends to shift to one side of the mechanical tolerances as the head sweep reverses.

[0005]

As described above, in the above conventional example, the ink droplets ejected from the nozzles adhere to wrong positions other than predetermined positions on the medium due to all the operations (actions). Regular images and text on the media,
An adverse effect on the visual image may appear. As a countermeasure, overlapping the "sweep width" of the sweep, for example, firing nozzles only during one-way sweep from the left to the right, or forming a large number of passages on the same area on the medium Several solutions have been found, such as selecting a droplet firing pattern that averages out mechanical errors. Techniques for automatic calibration to enhance the resulting print quality are also well known.

[0006] In addition to the problem of accurately firing ink at the proper location, there are the usual conditions for a mechanism to manipulate the vertical movement of the media, such that the nozzle array of the ink jet head must be able to reach the edge of the media. Because you can not move all over,
The inability to fire a drop of ink in both the left and right margins of the media. In addition, other mechanical constraints prevent the ink droplets from firing in the upper and lower margins of the media.

The present invention solves such problems in the prior art, and solves the problem of hysteresis and margin generation in the case of raster sweeping by an inkjet nozzle array on a flat medium. A method for printing on a region of a medium with an inkjet nozzle array that enables inkjet printing in one direction so as to reduce mechanical hysteresis and to eliminate the area of unprinted margins by printing along a trajectory path. It is intended to provide the ink jet printing system.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention solves the above-mentioned problems of hysteresis and margin when raster-scanning is performed on a flat medium by an inkjet nozzle array. That is, an improvement in the hysteresis problem is realized when the mechanical system does not start / stop multiple times or when the nozzle array is moving continuously with respect to the medium. Printing techniques according to aspects of the present invention satisfy that need by effectively achieving relative helical motion between the media and the nozzle array.
Further, the maximum diameter of the helix can be equal to the diagonal dimension of the square medium. This allows the droplet to be fired (adhered) to the most edge of the media. As a result, unprinted margin areas on both sides and the upper and lower portions of the medium are reduced or eliminated. It should be noted that the reduction or elimination of the blank area is appropriately described as “only no blank area”.

[0009] To this end, a method of printing an area of a medium with an inkjet nozzle array according to one aspect of the present invention comprises the steps of setting up an inkjet nozzle array and removing ink droplets ejected from the inkjet nozzle array during an inkjet printing cycle. Supporting the media flat to receive, firing ink droplets onto the media during an inkjet printing cycle, and the inkjet nozzle array defining a spiral trajectory relative to the media during the inkjet printing cycle. Setting relative motion between the inkjet nozzle array and the medium.

An ink jet printing system according to another aspect of the present invention includes an ink jet nozzle array for firing ink droplets during an ink jet printing cycle;
A flat medium positioned to receive ink droplets fired from the nozzle array during an inkjet printing cycle, the nozzle array such that the nozzle array defines a spiral trajectory relative to the medium during the inkjet printing cycle And a device for realizing relative movement between the medium and the medium.

As described above, the method for printing an area of a medium by the ink jet nozzle array and the ink jet printing system according to the present invention improve the problem that hysteresis and blank space are generated in the case of raster sweeping by the ink jet nozzle array on a flat medium. It is. In other words, printing is performed along a spiral trajectory path to reduce mechanical hysteresis, and ink jet printing in one direction can be performed so that an unprinted blank area is eliminated.

[0012] These and other features and advantages of the present invention will become apparent from the following detailed description of embodiments, as illustrated in the accompanying drawings, in which:

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a printing method for a region of a medium by an ink jet nozzle array and an ink jet printing system according to the present invention will be described in detail with reference to the drawings. In one embodiment, an inkjet printing technique is disclosed that provides relative movement between a nozzle array and a flat media surface without actually stopping or reversing the nozzle array or media. This is, in one embodiment, low (ρ), theta (θ)
By attaching a nozzle array to an arm extending from the coordinate center in the coordinate space of (1).

Here, ρ is the magnitude of the distance from the coordinate center, and θ is usually the angle in radians. This allows the nozzle array to move outward from this center while simultaneously rotating the medium around the coordinate center and with a circle. Alternatively, the nozzle array can be rotated and translated instead of the media to achieve a spiral trajectory for the media to be printed on the inkjet nozzles.

FIG. 1 is a perspective view showing a configuration of an embodiment of a printing method for a medium area by an ink jet nozzle array of the present invention and an ink jet printing system thereof, and shows an ink jet printing system 50 for carrying out the present invention. In FIG. 1, an inkjet pen 52 having a nozzle array 54 having inkjet nozzles 56 </ b> A to 56 </ b> N (FIG. 3 described below) arranged in a row is supported by a carriage 60. The carriage 60 is adapted to move along a scanning axis (carriage axis) 62.

A carriage driving system 70 is coupled to the carriage 60, and the carriage 60 is driven along a path along the scanning axis 62. Carriage drive system 70
Is a known configuration for scan width printers,
It has a drive motor 72, a belt drive 74, and an encoder stripe 76 with a pen scan encoder 78 (FIG. 8 described below) for providing carriage position data. The carriage drive system 70 shown in FIG. 1 does not require the high carriage speeds typically required for linear sweep width printers. Therefore, other drive mechanisms, such as a lead screw drive, can be used.

The medium 10 to be printed is the medium 10 here.
Is arranged on a flat turntable platen 80 mounted to rotate about a central axis 82 defining a coordinate center 86 in the plane of FIG. The turntable platen 80 is driven by a turntable drive system 90 that includes a turntable motor 92 and a turntable encoder 94 (see FIG. 8 described below) that provides position data for the turntable.

In the embodiment, an apparatus is provided for flatly supporting the medium to be printed on the turntable. Such devices include, for example, vacuum hold-down systems, electrostatic systems, mechanical systems with fixtures to hold the media in place, and the like, and are well known in the art.

A scanning axis (carriage axis) 62 intersects a linear nozzle array axis on a coordinate center 86 (see FIG. 3 described below).

FIG. 1 shows a second device (pen) 40 held by a carriage. This second
The device (pen) 40 is optional and can be a black inkjet pen (for example, the pen 40 in FIG. 8 described below).
B), or when the ink-jet pen 52 has three chambers, it may be a three-color pen having three nozzle arrays for firing ink droplets of three different colors. Both pens can use the movement of the pen carriage and the media turntable to sweep the same area on the media. For example, the inkjet pen 52 spirally sweeps when the second device (pen) 40 later sweeps the same 2π radian rotation region. As an alternative second device, an optical scanning head provided with an optical sensor array providing an optical scanner function may be used.

This is described in more detail with reference to agent reference number 1.
097031-1 "Method for Scanning Documents U
sing A Spiral Path Locus ", and is incorporated herein by reference in its entirety. An example of an optical scanning head suitable for this purpose is described in Haselby, filed September 23, 1996.
selby) et al. "UNDERPULSED SCANNER WITH VARIABLE
SCAN SPEED, PWM COLOR BALANCE SCAN MODES AND CO
No. 08/71, entitled "LUMN REVERSAL"
7,921, the entire contents of which application is incorporated herein by reference. For other applications,
The second device (pen) 40 is not used.

FIG. 2 shows a medium 1 during a printing operation according to the invention.
FIG. 9 is a diagram for explaining a relative movement path (that is, a spiral trajectory) of the nozzle array with respect to 0. Trajectory 1 in FIG.
Is a trace of a nozzle path of the inkjet pen 52 attached farthest (outside) from the coordinate center 86 with respect to the surface of the medium 10 to be printed. Region 1 is stationary such that when the nozzle array is closest to the coordinate center 86, the inner nozzle is located above the coordinate center 86, and the nozzle at the locus 1 is furthest (outer) from this center. This is a circular area defined by the relative sweep of the nozzle set by the rotation of the nozzle array and the medium. Area 2 shows a typical rectangular print area having a width W and a height H.
Region 3 is bounded by a circle indicating the outer boundary where ink droplets can be deposited.

FIG. 3 shows the ink jet nozzles 56A to 56A-5.
FIG. 4 is a schematic diagram illustrating a simplified nozzle array 54 having 6N. Position 1 shown in FIG. 3 shows the nozzle array at the start position with respect to the surface of the medium 10, and the inkjet nozzle 56A is located at the coordinate center 86 of the platen. Position 2 shows the relative rotation (angle theta) between the nozzle array 54 and the medium 10. In this embodiment, the carriage is stopped during the first rotation of the turntable platen 80 and completely covers region 1. That is, sweeping is performed completely. This first complete relative rotation is circular and also causes the inkjet nozzle 5
6A remains at the coordinate center 86 in FIG. In the second rotation, the carriage begins to move, providing a spiral relative path as shown in FIG. 4 below.

FIG. 4 shows that the medium 10 rotates for the second time (2
π radian), that is, the carriage is moved along with the scanning axis (carriage axis) 62 with the rotation of the turntable platen 80.
FIG. 9 is a diagram simply illustrating the path of the outermost inkjet nozzle 56N when a given movement is made along the arrow. The path shown in FIG. 4 starts from the position A of the inkjet nozzle 56N with θ = 0 and the radius ρ = 1 unit (1 unit is equal to the width of the nozzle array), and the inkjet nozzle with θ = 2π and ρ = 2 units. The process ends at a position E of 56N. Ink jet nozzle 56N has θ = π / 2, ρ = 1.2
Position B of 5 units and position C of θ = π, ρ = 1.5 units
And the position D of θ = π and ρ = 1.75 units, the path shown for the medium 10 is followed.

During the second rotation, that is, during the first rotation after the carriage starts moving, the coverage of the print nozzles overlaps with the first rotation. During the second rotation, it is preferable to execute a control program in the printer control device so as to suppress firing from the nozzles to the overlapping area and prevent double dots. Also, the ink droplets or dots are preferably evenly spaced along a spiral path according to standard design practices.

FIGS. 2 and 4 relate to this embodiment. In the radial movement of the nozzle array, each time the medium 10 on the turntable platen 80 rotates by 2π radians (360 degrees), the nozzle array moves in the radial direction. This shows a state in which the movement is restricted by one width. Thus, in FIG. 2, the spiral path does not overlap or underlap the path. For the third rotation of the turntable platen 80 and all subsequent rotations, there is no overlap of the nozzle array coverage with the initial rotation / passage of the nozzle array.

In a known Cartesian printer in many applications, in order to prevent swathing of the swath, ie, to prevent spiral swathing, as is currently done, It is desirable to overlap the routes. In this case, the nozzle array is moved by a distance smaller than the nozzle array width (one unit) every time the medium 10 rotates 2π radians.

FIG. 5 is a diagram for explaining an example of a spiral locus of such overlapping cases. In the example of FIG. 5, the carriage moves outward by 0.5 unit (nozzle array width) each time the nozzle array makes one complete rotation. Alternatively, the nozzle array may move a distance greater than the nozzle array width each time the medium 10 rotates 2π radians, providing a gap in the print range as the nozzle array moves outward. Such gaps are filled with reverse spiral scans that move the nozzle array from the outer position shown in FIG. 3 to the starting position.

FIG. 6 shows an example of a spiral locus in the case of such an underlap. In the example of FIG. 6, the carriage has two nozzle arrays every one complete rotation.
Move outward by a unit (nozzle array width). When the nozzle array is over area 1, ink droplets
Platen 80 so that it can be completely covered.
This position must be maintained during the first revolution of the upper medium 10.

Next, in the second and subsequent rotations of the turntable platen 80, every time the nozzle array moves outward, all remaining areas of area 3 may become targets for ink droplets. I can do it. Area 3 is circular, but most of the media that one wishes to print is usually rectangular, as shown in rectangular print area 2. To fully cover this area, the innermost nozzles of the nozzle array need to move outward from the center of the coordinate, and the outermost nozzles reach the corners furthest from the center of the media Must be able to do it.

In most cases, to minimize the total printing time of the print job, the inkjet nozzles fire a fixed rate of droplets, but this is not required for the present invention. However, if such an operation is required, the speed along the helix of a given nozzle will be a constant rotational speed (d
θ / dt), the rotation speed of the turntable platen 80 becomes dS using the differential d in [1] differential notation when S is the tangential distance along trajectory 1. = Ρ * dθ, [2] t means time, and V
Is the desired constant speed along trajectory 1, dS / d
The adjustment is performed so that t = ρ * dθ / dt = V. [3] When ρ starts with one nozzle unit width, dθ / d
Solving t = V / ρ reaches (W ² + H ² ) ^1/2 / 2 when the entire area of the medium is covered. Since ρ is a variable at the denominator position, if the tangential velocity of the head must be constant, the rotational speed is a non-linear function of the position of the inkjet head.

FIG. 7 shows a graph plotting an example of the angular velocity of the head as a function of the radial distance from the coordinate center. In other words, when the innermost nozzle is at the center of rotation, the maximum rotation speed of the medium is 1 radian / second, and the minimum rotation speed is 2 / (W ² + H ^{2) for} a nozzle array of one unit length. ) ^1/2/2 seconds.

As an example, 30 each equally spaced from the neighbor by 1/300 inch (0.085 mm)
Using an inkjet array consisting of 0 nozzles,
Suppose you want to print 8.5 to 11 inch (21.6 x 27.9 cm) media edge to edge. In this case, the array is one inch (25.4 mm) in length. Inkjet pens are typically designed for maximum firing speed. Thus, where f is the firing velocity (frequency), equally spaced droplets indicate the distance that the pen (head) moves in 1 / f seconds.

Thus, the maximum speed of the pen (head) is set. Further, while firing the dots at their maximum velocity, the maximum tangential velocity of this nozzle array is 10.
Assume 0 inches (25.4 cm) / sec. Thus, when the head moves over the media at this speed and the “sweep width” is 1.0 inch (25.4 mm) wide,
10 * 300 = 3000 dots are fired per second.

The maximum position at which the nozzle farthest from the center of rotation needs to move away from the center is, for example, (W ² + H
^{2) 1/2} /2=(8.5 ² +11 ^{2)) 1/2} /2=6.95
In inches (17.7 cm) and when the outer limit of ρ is reached, the rotational speed is dθ / dt = V, as shown in FIG.
/Ρ=10.0 inches / second / 6.95 inches = 1.44
Radians / second, or about 13.75 RPM (rotation speed / minute)
It is. The tangential speed is the rotation speed multiplied by the radius. This is, as expected, 1.44 * 6.95 = 10 inches (25.4 cm) / sec.

Next, the nozzle farthest from the center of rotation is
At ρ = 1.0 inch (2.54 cm), the rotation speed is 10.0 inches per second, as shown in FIG.
0 inches = 10.0 radians / second, or about 95.5 RP
M.

The total printing time is 10 square inches (64.5).
cm ² ) / sec (the area swept by the head per second is the product of the length of the nozzle and the distance moved per second) and is approximated as the time required to sweep the entire circular area of area 3 at a constant speed. You can do it. The total area of the “sweep” circle is π * (radius ² ) = 3.14159 * (6.95 ² )
= 151.75 square inches (979 cm ² ), where the radius is half the diameter dimension of region 2. 10 per second
Square inches (64.5 cm ² ), which is about 15.2
Seconds.

When an image composed of rows and columns of normal data pixels or picture elements is drawn in the conventional method, the quantum coordinates between the Cartesian coordinates of the rows and columns and the ρ-θ coordinate system shown in FIG. Droplet is the desired "Cartesian" due to the effect of chemical type
Some media areas are not accurately deposited based on coordinates. The maximum error in the above scheme occurs at a rotation angle of 180 degrees or π radians, where π represents the ratio of the circumference to the diameter of the complete circle. By re-sampling the raster Cartesian data to ρ-θ coordinates using well-known digital techniques (eg, convolution), printing errors are minimized. Te
chnique for Scanning Documents Using A Spiral Path
A co-pending application entitled "Locus" describes a technique that obviates the need for such coordinate transformations.

FIG. 8 is a simplified circuit diagram of the control system of the printer system shown in FIG. Control device 10
0 is connected to the memory 102 to retrieve the data defining the print job. The control device 100 generates a drive command to the drive motor 72 including the carriage drive mechanism, and receives a position signal indicating the carriage / pen position from the pen scan encoder 78. The control device 100
Generates a turntable motor drive command for controlling the turntable motor 92 that rotates the turntable platen, receives an encoder signal from the turntable encoder 94, and determines the position and angular velocity of the turntable platen.

Thus, the control device 100 controls the carriage drive so that the spiral trajectory of the pen nozzle array does not overlap the medium, and the trajectory overlaps to prevent banding and other errors. Wrap or underlap the trajectory to achieve other special printing modes. Examples of other print modes include:
In some printers, the spiral is formed by omitting the printing of the alternating rotation, the direction of the carriage is reversed at the end, and the dots omitted by the alternating rotation are filled.

The control device 100 also controls the nozzle array 54 according to the image to be generated and the position of the pen with respect to the coordinate center.
Supply a firing pulse. The image data is stored in the memory 102
May be received from the host computer 120. Further, the control device 100 can set the firing speed of the nozzle array 54. In many cases, it is desirable to use a constant (maximum) firing rate, but for other jobs and applications, the controller 100 may use a slower firing rate that is not constant throughout a particular print job. The firing speed can be controlled in this way. By changing the firing speed, the density of dots can be increased or decreased in specific areas on the medium 10.

Each nozzle of the nozzle array 54 is at a different radial distance from the coordinate center 86 than the other nozzles.
For this reason, by firing all the nozzles at a constant speed, a difference in dot interval that is easily recognized when ρ is a small value occurs, particularly in the area 1 in FIG. For example, in region 1 of the medium during initial rotation (without accompanying radial movement of the carriage), if the nozzle spacing is 1/300 inch (0.085 mm), then ρ is the inkjet nozzle 56N furthest from the center of rotation. (FIG. 3) must be fired 300 times per inch along the circumference. For a 1 inch nozzle array, the circumference is 2π inches.

Therefore, along this circumference, 1/300
1,885 dots are printed at intervals of inches (0.085 mm). The circumference of the second inkjet nozzle 56B deviated from the coordinate center is only 2π / 300 inches, that is, 0.0209 inches (0.53 mm).
It is inappropriate to fire 1,885 dots of ink along the circumference because too much ink is generated along the circumference. For a nozzle one inner than the outermost nozzle, i.e., a nozzle closer to 1/300 inch (0.085 mm) around the center of rotation, the number of dots fired to maintain 300 dots per inch is , 2π (1.0−1 / 300) (300), that is, 1,879.

However, if the firing speed is the same as that of the outermost nozzle, 1,885 dots are actually fired, so that the generated dot is generated by the outermost nozzle. You will be closer than you are. During area 1 sweeps or in other areas of the medium, the printed pixels must not be reprinted, and the logic in the controller 100 can easily determine which pixels each nozzle should print. It is possible to reduce the frequency of firing the nozzle near the center of rotation.

As yet another example, when the nozzle array reaches a ρ value of 2.0 after the second rotation of the medium, the inkjet nozzle 56A (closest to the center of rotation) has a ρ value of 1.0. Yes, it must fire at half the speed of the outermost nozzle to maintain the same dot spacing. Also in this case, the logic circuit in the control device 100 adjusts the firing speed so that ink does not adhere to the printed pixels. However, it is desirable to minimize the total printing time by firing the inkjet nozzle 56N, the outermost nozzle, at the maximum (constant) speed possible. In FIG. 7, when the outermost nozzle has a constant (maximum) speed, the pixel to be printed is at least 1/300 inch (0.085 mm) from the adjacent pixel.
FIG. 6 shows the relationship between the actual firing speeds of all the other nozzles when they are away from each other. This will always result in a firing speed that is lower than the maximum firing speed. Such a difference in speed rapidly decreases as the distance from the rotation center increases.

It is to be understood that the above-described embodiments are merely illustrative of specific embodiments that can represent the principles of the present invention. For example, other configurations can be used to achieve the desired relative movement between the pen and the print media to achieve a spiral path. For example, a pen can be placed on an arm mechanism that moves along a spiral path with the print medium placed on a stationary platen. Alternatively, on the contrary, the pen may be arranged at a stationary position, and the print medium may be arranged on a platen that realizes a desired spiral movement trajectory. Also, the pen movement has been described as starting from the coordinate center position and moving outward in the radial direction. Alternatively, the pen may start moving from any other position, for example, moving from the outermost position. At the beginning, the spiral may move inward and end at the coordinate center. Those skilled in the art can easily devise other configurations based on such principles without departing from the scope and spirit of the present invention.

The embodiments of the present invention will be summarized below. 1. A method of printing an area of a medium with an inkjet nozzle array, comprising the steps of: configuring an inkjet nozzle array (54); and flattening to receive ink droplets fired from the inkjet nozzle array (54) during an inkjet printing cycle. Supporting a medium (10); firing ink droplets onto the medium (10) during an inkjet printing cycle; and causing the inkjet nozzle array (54) to move the medium (10) during the inkjet printing cycle. A) setting a relative movement between the inkjet nozzle array (54) and the medium (10) so as to define a spiral trajectory with respect to).

2. The method of claim 1, wherein the step of setting the relative movement comprises periodically stopping the inkjet nozzle array (54) during a printing cycle and without reversing this direction. . 3. Setting the relative movement by attaching the inkjet nozzle array (54) to an arm extending from the center of coordinates, wherein the inkjet nozzle array (54) is armed while rotating the medium (10) around the center of coordinates; 3. The printing method for a region of a medium by the inkjet nozzle array according to the above 1 or 2, further comprising the step of moving outward from the coordinate center. 4. Setting the relative movement over a first distance in a direction in which the inkjet nozzle array (54) extends radially from the center of coordinates, wherein each time the medium (10) makes one revolution around the center of coordinates, 4. The inkjet nozzle array of claim 3 including the step of moving the inkjet nozzle array (54) in the radial direction at the same rate so that the inkjet nozzle array (54) moves radially by a distance equal to the first distance. The printing method for the area of the media. 5. Setting relative motion over a first distance in a direction in which the inkjet nozzle array (54) extends radially from the center of the coordinate, wherein the medium (10) rotates once around the center of the coordinate; The inkjet nozzle array of claim 3, including the step of moving the inkjet nozzle array (54) in the radial direction at the same rate so that the inkjet nozzle array (54) moves radially at a distance shorter than the first distance. The printing method for the area of the media. 6. The inkjet nozzle array (54) has a plurality of nozzles (56A-56N) including an outermost nozzle (56N) with respect to a coordinate center, and firing droplets of ink during an inkjet printing cycle, Firing ink droplets from the outermost nozzle at a constant velocity, and setting the relative movement, wherein the tangential velocity of the outermost nozzles of the inkjet nozzle array (54) is substantially constant; 4. The method for printing on a region of a medium by an inkjet nozzle array according to the above 3, further comprising the step of changing the relative rotational speed of the medium (10) so as to make the medium more opaque. 7. The step of relative movement between the inkjet nozzle array (54) and the medium (10) achieves a partial overlap of the inkjet nozzle array (54) with respect to the medium (10) during a printing cycle. Moving the inkjet nozzle array (54) in the radial direction at a speed selected as described above.
3. A printing method for an area of a medium by the inkjet nozzle array according to any one of 3. 8. The step consisting of relative movement between the inkjet nozzle array (54) and the medium (10) achieves a partial overlap of the inkjet nozzle array (54) with the medium (10). The inkjet nozzle array (5
4) The method for printing on a region of a medium by the inkjet nozzle array according to any one of the above 1 to 3, wherein the method includes a step of moving the radial direction. 9. The step of setting the relative motion includes the step of:
Inkjet nozzle array (5
The method for printing an area of a medium by an inkjet nozzle array according to any one of the above 1 to 8, wherein the inkjet nozzle array (54) has a step of moving the inkjet nozzle array (54) in a radial direction by a sufficient distance when sweeping.

10. An inkjet nozzle array (5) that fires ink droplets during an inkjet printing cycle.
4) and a flat medium (10) positioned to receive ink droplets ejected from said inkjet nozzle array (54) during an inkjet printing cycle.
And relative movement between the inkjet nozzle array (54) and the medium (10) such that the inkjet nozzle array (54) defines a spiral trajectory with respect to the medium (10) during an inkjet printing cycle. (60, 72, 80, 92) for realizing the inkjet printing system (50). 11. Apparatus (60, 72, 80, 92) for realizing relative movement between the inkjet nozzle array (54) and the medium (10) includes an ink jet nozzle for the medium (10) during a printing cycle. The inkjet printing system of claim 10, wherein the inkjet nozzle array (54) is adapted to move radially at a speed that achieves partial overlap at the nozzle array (54). 12. Apparatus (60, 72, 80, 92) for realizing relative movement between the inkjet nozzle array (54) and the medium (10) is provided with respect to the medium (10). The inkjet printing system of claim 11, wherein the inkjet printing system is adapted to move the inkjet nozzle array (54) in a radial direction at a speed that sets a partial overlap in (). 13. An inkjet pen (52) to which the inkjet nozzle array (54) is attached; and a carriage shaft (6) holding the pen and extending through the center of coordinates.
2) a pen carriage (60) mounted to move along the carriage axis; and an arm structure supporting the pen carriage to move along the carriage axis, wherein the device for setting relative movement comprises a pen. Drive device (7) for moving the arm outward from the coordinate center on the arm.
12. The inkjet printing system according to the above-mentioned 11, further comprising 2) and a rotation driving mechanism for rotating the medium (10) around a coordinate center. 14． The ink jet nozzle array (54) is arranged such that the carriage driving device (72) rotates the medium (10) around the coordinate center by one rotation over a first distance in a direction extending radially from the coordinate center. The inkjet printing system of claim 13, further comprising the step of moving the inkjet nozzle array (54) in the radial direction at the same speed such that the inkjet nozzle array (54) moves radially at a distance equal to the first distance. 15. A controller (100) generates nozzle firing instructions that cause the inkjet nozzle array (54) to fire ink droplets from a given nozzle, including the nozzle array, at a constant rate during a printing cycle, causing the medium (10) to be discharged. An inkjet printing system according to any of claims 10 to 14, wherein the rotating device is adapted to vary the rotational speed of the medium (10) to make the tangential speed of the inkjet nozzle array (54) substantially constant. 16. The controller (100) generates a nozzle firing command to cause the inkjet nozzle array (54) to fire ink droplets at a variable speed during a printing cycle.
15. The inkjet printing system according to any one of items 14 to 14.

[0050]

As is apparent from the above description, according to the printing method for the area of the medium by the ink jet nozzle array of the present invention and the ink jet printing system, the raster sweeping by the ink jet nozzle array on the flat medium is performed. Hysteresis and margin issues are improved. That is, printing along a spiral path,
Inkjet printing in one direction is possible, reducing mechanical hysteresis and eliminating the area of unprinted margins.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of an ink jet printing system according to an embodiment of a printing method for an area of a medium using an ink jet nozzle array of the present invention and the ink jet printing system.

FIG. 2 is a view for explaining a relative movement path (spiral locus) of a nozzle array with respect to a medium during a printing operation in the embodiment.

FIG. 3 is a schematic view showing a simplified nozzle array having a plurality of nozzles according to the embodiment at two positions with respect to a flat medium surface.

FIG. 4 is a simplified illustration of the path of the outermost nozzle when the medium rotates a second time (when the carriage makes a given movement along the carriage axis with the rotation of the platen) in the embodiment. FIG.

FIG. 5 is a diagram illustrating a first alternative path during one rotation of the medium of the outermost nozzle of the nozzle array when the spirals of the nozzle array partially overlap in the embodiment.

FIG. 6 is a view for explaining a second alternative path during one rotation of the medium of the outermost nozzle of the nozzle array when the spiral of the nozzle array partially underlaps in the embodiment.

FIG. 7 is a diagram (graph) showing the angular velocity of a flat medium as a function of radial distance for maintaining the tangential velocity of the nozzle array in the embodiment.

8 is a simplified circuit diagram showing a control system of the printer system shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Medium 40 2nd apparatus (pen) 50 Ink-jet printing system 52 Ink-jet pen 54 Nozzle array 56A-56N Ink-jet nozzle 60 Carriage 70 Carriage drive system 72 Drive motor 74 Belt drive mechanism 76 Encoder stripe 78 Pen scan encoder 80 Turntable platen 90 Rotation Table drive system 92 Turntable motor 94 Turntable encoder 100 Controller 102 Memory 120 Host computer

Claims (1)

[Claims] 1. A method of printing an area of a medium with an inkjet nozzle array, the method comprising: configuring an inkjet nozzle array (54); and receiving ink droplets fired from the inkjet nozzle array (54) during an inkjet printing cycle. Supporting the medium (10) so as to be flat, firing ink droplets onto the medium (10) during an inkjet printing cycle, and controlling the inkjet nozzle array (54) during the inkjet printing cycle. Setting relative motion between the inkjet nozzle array (54) and the medium (10) to define a spiral trajectory for the medium (10). A printing method for an area of a medium by an inkjet nozzle array.