JP2000158711A - Interlace type printer and interlace type printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer and a print method which can solve banding resulting from a transfer error of a print medium or the like. SOLUTION: A medium transfer mechanism 14 moves a medium 100 by a pitch feed unit so that a dot pitch distance in a sub scan direction of print images becomes D/t (t: 3 or larger integer and D: a distance between dot form elements). A medium transfer mechanism control part 17 sends to the medium transfer mechanism 14 pitch feed amount data obtained by adding a data DΔ corresponding to a change amount Δi expressed by Δi=-δi×(D/t) in which i: 1, 2,..., t, δi: >=-(t-2), <=(t-2) and Σδi=0 to a data Du corresponding to a pitch feed reference amount U expressed by U=N×(D/t) in which N: the number of dot form elements having a relationship of a 'prime' to the t, while sending the pitch feed amount data by t times is one cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interlaced printing technique, and more particularly, to a method for eliminating unevenness (such as banding) in a printout image caused by a transport error of a print medium (hereinafter, simply referred to as "medium"). It relates to a printer and a printing method that can be used.

[0002]

2. Description of the Related Art In recent years, printers tend to have higher resolution regardless of the print format. In a dot-impact printer (dot-impact printer), the interval between pins arranged on the print head is reduced, and in an ink-jet printer (ink-jet printer), the interval between nozzles arranged on the print head is reduced. By reducing the size, the resolution can be increased.

However, in these printers, there is a limit in reducing a pin interval or a nozzle interval due to a problem in mechanism. In a normal printing method (a method in which dot rows in the main scanning direction are printed in an adjacent order, that is, in a line arrangement order), the resolution is the same as the arrangement density of pins and nozzles, that is, 60 dpi (d) in a dot impact printer.
about per inch), and an ink jet printer can only obtain a resolution of about 180 dpi.

[0004] For this reason, in the dot impact printer and the ink jet printer, printing by the interlace method is performed in order to increase the resolution. FIG. 4 is an explanatory diagram illustrating an outline of the ink jet printer 6 that performs printing in the interlaced mode. The printer 6 includes a print head 61 and a mechanical system,
A carriage 62 on which the print head 61 is mounted;
A carriage driving mechanism 6 for moving the carriage 62
3 and a medium transport mechanism 64, and the control system includes a print head controller 65, a carriage drive mechanism controller 66, a medium transport mechanism controller 67, and an image analysis processor 68. I have.

[0005] In FIG. 4, a medium transport mechanism 64 includes a medium transport roller 641, a stepping motor 642, and a plurality of gear groups 644 interposed therebetween. The driving force of the stepping motor 642 is transmitted to the medium transport roller 641 via a group of gears 644. The medium transport roller 641 sandwiches the medium 100 between the medium 100 and the medium transport auxiliary roller 643, and moves in the sub-scanning direction (y direction). ) In a predetermined pitch unit.

The carriage driving mechanism 63 includes a timing belt 631, a motor (not shown), a pulley 6
32. The pulley 632 is connected to the carriage 62
The shaft is rotatably mounted on the
The carriage 62 can reciprocate in the main scanning direction (± x direction) via the pulley 632 by receiving a driving force from a motor (not shown).

In the printer 6 shown in FIG. 4, a print head 61 has 15 nozzles NZ _{1 to} NZ (not shown).
₁₅ is 18 in the sub-scanning direction (the transport direction of the medium 100).
It is formed at 0 dpi (ie, at an interval of 1/180 inch). Since the resolution of the printer is usually expressed in dpi, it is convenient to express the dimensions of the members constituting the transport mechanism of the medium 100, the transport distance of the medium 100, and the like in “inch”. Therefore, in this specification, "inch" is used as a unit of length.

When printing is performed so that the resolution in the sub-scanning direction is 720 dpi, the medium transport mechanism controller 6
Reference numeral 7 designates a value corresponding to one pitch feed (1/48)
0 inch), and the medium transport mechanism 64 rotates the stepping motor 642 by an amount corresponding to the pitch feed amount data PTD at a predetermined timing. Thereby, the medium transport roller 64
No. 2 transports the medium 100 by one pitch. The carriage driving mechanism 63 moves the carriage 62 in the main scanning direction during the period in which the conveyance of the medium 100 is stopped, and the print head 61 moves the ink droplets from predetermined nozzles based on a control signal from the print head controller 65. Fire,
Perform printing.

FIGS. 5A and 5B are diagrams for explaining the principle of printing by the conventional interlace method. Here, for convenience of explanation, it is shown that the medium 100 is stationary and the print head 61 is moving. FIG. 5 (A)
Then, during the conveyance stop period of the medium 100, the nozzle N
The theoretical positions of ink droplets from Z _{1 to} NZ ₁₅ are indicated by solid squares. Further, in FIG. 5B, the drop positions in principle of the ink droplets from the nozzles NZ _{1 to} NZ ₁₅ during the transport stop period after the medium 100 is fed by one pitch are indicated by black triangles. I have. For easy understanding, in FIGS. 5 (A) and 5 (B), white squares are also arranged at portions other than the black squares and the black triangles. As described above, by successively feeding ink droplets onto the medium 100 with four consecutive pitch feeds, printing can be performed at a resolution of 720 dpi, which is four times the nozzle density of 180 dpi in the sub-scanning direction.

[0010]

However, due to the eccentricity of the rotation shafts of the medium conveyance rollers 641 and the gear group 644, the conveyance distance of the medium 100 by one pitch by the medium conveyance mechanism 64 is originally planned. And the dot distance in the sub-scanning direction may not be equal. It is expected that the error of the dot interval usually appears periodically with respect to the transmission of the pitch feed amount data PTD.

FIGS. 6A to 6D show the positions at which dots (ink droplets) are successively deposited in the sub-scanning direction when ink droplets are deposited on a medium by four consecutive pitch feeds. Is shown. In FIG. 6 (A), the first pitch feeding, shows the dripping position of ink droplets from the nozzle _{NZ 15} and _{NZ 14} Metropolitan by a black circle _P 1, _{P 5,} FIG. 6 (B), 2 nd pitch in the feed, it is shown dripping position of ink droplets from the nozzle NZ ₁₁ by a black circle P _2. FIG. 6 (C)
So the third pitch feeding, shows the dripping position of ink droplets from the nozzles NZ ₇ by black circles P _3, in FIG. 6 (D), the at fourth pitch feeding, application of ink droplets from the nozzle NZ ₃ It is shown ejection position by a black circle P _4. 6 (A) to 6 (D), the setting positions of P ₁ , P ₂ , P ₃ , P ₄ , and P ₅ (original ink droplet deposition positions) are indicated by dotted lines.

FIG. 6 shows a case where the actual pitch feed amount is smaller than the original pitch feed amount L by δ _{L in} each pitch feed. FIG.
(D) As can be seen from, for dripping position P ₁ in the first pitch feed, the error in the dripping position P ₄ at the fourth pitch feed, a second time, the error is accumulated in the third pitch feed , P ₄ total 3δ _{L to} P ₅
Approaching the distance.

FIG. 7 shows a case where the actual pitch feed amount is larger than the original pitch feed amount L by δ _{L in} each pitch feed. In FIG. 7 (A), the first pitch feed, the nozzles _{NZ 15} and N
Black droplets P ₁ and P ₅ indicate the positions where the ink droplets land from Z _{14. In} FIGS. 7B, 7C, and 7D, the nozzles in the second, third, and fourth pitch feeds are shown. NZ ₁₁ , N
The positions where the ink droplets are deposited from Z ₇ and NZ ₃ are indicated by black circles P ₂ , and in FIG. 7C, in the third pitch feed,
The dripping position of the ink droplet black circle _P 2 from the nozzle NZ _7, P
_3, is indicated by _{P 4.} In the case of FIG. 7, for dripping position P ₁ in the first pitch feed, to the fourth error of dripping position P ₄ in the pitch feed, a second time, the error is accumulated in the third pitch feed, P ₄ would be separated by a distance of total 3δ _L with respect to _{P 5.}

Due to such a shift of the ink droplet landing position from the original position, a band pattern (light-colored stripe pattern or dark-colored stripe pattern) called, for example, banding occurs in the printed image. Or unevenness in the image, resulting in deterioration of image quality.

The present invention has been made to solve the problem that the error of the pitch feed amount is accumulated every time the number of pitch feeds is increased. Another object of the present invention is to provide an interlaced printer and an interlaced printing method which can prevent or improve the image quality caused by the pitch feed amount error by a simple means or technique.

[0016]

As described above, in a conventional interlaced printer, for example, a print head having N nozzles in the sub-scanning direction is used to print an image in the sub-scanning direction. Resolution is 1
/ D (dpi) (where D: interval between dot forming elements)
(A) Among the dot rows in the main scanning direction, printing is performed in the order of dot rows in each row group in which continuous t rows constitute one group. The transport mechanism transports the medium without changing the set amount of pitch feed.

The present inventor has focused on the above (a) and (b) and made various studies. As a result, among the dot rows in the main scanning direction, in each row group having continuous t rows as one group, If the printing of each dot row is performed in a different order from the arrangement order of the dot rows (that is, if the set amount of the pitch feed of the medium is changed), the pitch feed amount error described above can be reduced. Based on the knowledge, the present invention has been accomplished.

The interlaced printer of the present invention (hereinafter simply referred to as “printer of the present invention”) is a dot impact type or ink jet type printer.
Dot pitch interval P in the sub-scanning direction of the image to be printed
Where D / t, where t is an integer of 3 or more, and D is the interval between dot forming elements.

The printer of the present invention has a print head, a carriage, a carriage drive mechanism, a medium transport mechanism, a print head control section, a carriage drive mechanism control section, and a medium transport mechanism control section, similarly to a conventional interlaced printer. are doing.

In the print head, dot forming elements (pins and nozzles) are arranged at predetermined intervals in the sub-scanning direction. The print head is mounted on the carriage,
The carriage drive mechanism control unit controls the carriage drive mechanism,
The carriage driving mechanism sends a reciprocating timing signal and the like, and the carriage driving mechanism reciprocates the carriage in the main scanning direction.

The print head controller drives the print head in accordance with the reciprocation of the carriage in the main scanning direction, and causes a predetermined dot forming element to print a dot row in the main scanning direction. The “printing of dot rows” here includes printing of blank rows (that is, not driving the dot forming elements over the entire dot rows) and printing of some of the dot rows (that is, printing of some of the dot rows). Drives the dot-forming element, but does not drive the dot-forming element for the other parts).

The medium transport mechanism control unit controls the medium transport mechanism
The pitch feed amount data is transmitted in pitch units. The medium transport mechanism transports the medium in the sub-scanning direction at a predetermined pitch feed amount based on the pitch feed amount data.

The print head control unit, the carriage drive mechanism control unit, and the medium transport mechanism control unit may be constituted by, for example, a dedicated processor (microprocessor, digital signal processor, etc.) or may be constituted by mutually independent circuits. Can also. Further, at least a part of these control units may be configured by a common circuit.

In the printer of the present invention, the medium transport mechanism control section corresponds to a pitch feed reference amount U represented by the following equation (1), where transmission of pitch feed amount data t times to the medium transport mechanism is one cycle. This is configured to transmit pitch feed amount data obtained by adding data corresponding to a change amount _ｉi expressed by the following equation (2) to the data to be changed.

U = N × (D / t) (1) where N: the number of dot forming elements having a relation of “prime” with each other D: interval of dot forming elements Δ _i = − δ _i × (D / t) (2) where, i: 1, 2,..., t δ _i : an integer ≧ − (t−2), ≦ (t−2), ， δ _i = 0 In the above equation, D / t is a distance equivalent to the dot interval in the sub-scanning direction of the image, and δ _i is information (value) corresponding to the pitch feed change amount △ _i . The calculation for setting Σδ _i = 0 can be performed by, for example, an appropriate counter.

[0026] In the printer of the present invention, the medium transport unit controller, the change amount storage means for storing information [delta] _i are provided. The change amount storage means stores δ ₁ , δ ₂ ,.
as long as it can store the [delta] _t, it is a memory may be a register. The change amount storage means constitutes a part of the medium transport mechanism control unit. For example, when a register of the image processor is used as the change amount storage means, the change amount storage means It can be provided separately from other parts (parts other than the change amount storage means) of the medium transport mechanism control unit.

The information δ ₁ ,
δ _{2, ···,} δ _t are each, pitch feed variation △ _1, △ _2, · · ·, as long as it is associated with △ _t, may be used what code. For example, t
= 4, the possible values of δ _i are -2, -1,
0, +1, +2. When these values are stored in a register, δ ₁ , δ ₂ , δ ₃ , δ ₄ are binary numbers representing the magnitude of a numerical value, such as 110, 101,000, 001, 010, in the register. Notation may be stored, or a binary code notation that does not represent the magnitude of a numerical value, for example, 000,001,010,011,100
And so on.

[0028] The change amount storage unit (e.g. register), having a storage unit of fewer tau than t, [delta] ₁ to the tau-number storage _unit, [delta] _2, · · ·, tau pieces of information of the [delta] _t Is stored ((t−τ) pieces of information are not stored). For example, when t = 4, the transmission of the pitch feed amount data four times is defined as one cycle, and △ ₁ ,
The change amounts of Δ ₂ , Δ ₃ , and Δ ₄ are added to the pitch feed reference amount U, but it is not necessary to set all of Δ ₁ , Δ ₂ , Δ ₃ , and Δ ₄ to values other than 0, and usually, At least one of these values is set to zero. For example, when △ ₁ is always 0, because the storage unit of the register for [delta] ₁ is not required, the register, [delta] _2, [delta] _3, sufficient if provided to the storage unit for the [delta] _4.

The print head is provided with a plurality of dot forming elements as described above. Interlaced printing is performed by the number N of dot forming elements having a “prime” relationship with t. However, the printer of the present invention is not limited to the number N described above, and a larger number of dot forming elements can be provided in the print head. For example, the number of dot-forming elements provided on the print head, by more than the number N, during printing, the pitch feed amount of change △ _1, △ _2, · · ·, the value of △ _t, the equation (2) The condition can be changed to satisfy the condition.

[0030] In the printer of the present invention, in advance, the change amount storage means, the amount of change △ _1, △ _2, · · ·, information [delta] ₁ corresponding to _{△ t, δ 2, ···,} δ t is stored You. The information δ ₁ , δ ₂ ,..., Δ _t can be written into the change amount storage means from outside the printer by visually observing and examining the image output by the test print. Alternatively, it can be written in the change amount storage means at the time of quality inspection before shipping. Also, software for a printer drive, drawing software, or the like may write the information δ ₁ , δ ₂ ,..., Δ _t into the change amount storage means.

The medium conveying mechanism control unit sending the t times the pitch feed amount data as one cycle, sequentially pitch feed variation △ _1, △ _2, · · ·, data about △ _t, pitch feed reference amount The pitch feed amount data PTD is created by adding to the data for U, and this is output to the medium transport mechanism.

The print head control section can know which dot forming element should be driven by referring to the information δ ₁ , δ ₂ ,..., Δ _t stored in the change amount storage means. .

In the printer of the present invention, printing is performed in an order different from the arrangement order of the dot rows for each group of continuous t rows among the dot rows in the main scanning direction. Therefore,
As shown in FIGS. 2 and 3, which will be described later, the deterioration of the image quality due to the pitch feed amount error of the dot forming element is improved.

The interlaced printing method of the present invention (hereinafter simply referred to as the “printing method of the present invention”) is a method of printing an image printed by a print head in which dot forming elements are arranged at predetermined intervals in the sub-scanning direction. The present invention is applied to a printing method in which a dot pitch interval P in the scanning direction is D / t, where t is an integer of 3 or more and D is an interval between dot forming elements.

In the printing method of the present invention, the pitch feed reference amount U expressed by the above equation (1) is added to the above equation (2) for each group of continuous t rows among the dot rows in the main scanning direction. ), The medium is conveyed by the pitch feed amount to which the change amount で_i is added, whereby the group of t rows is printed in a different order from the arrangement order of the dot rows.

According to the printing method of the present invention, printing is performed in a different order from the arrangement of the rows for each group of continuous t rows among the dot rows in the main scanning direction. Image quality degradation due to volume errors is improved.

Although the printing method of the present invention can achieve the same object as the printer of the present invention, it is not always carried out only by the printer of the present invention. For example, a register for setting the order of the dot rows to be printed is prepared, and the printing order of the dot rows is determined according to the value of the register. The medium transport mechanism control unit controls the pitch corresponding to the order. It is also possible to control the medium transport mechanism so as to obtain the feed amount.

[0038]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention. In FIG. 1, an ink jet printer 1 includes a print head 11, a carriage 12, a carriage drive mechanism 13, a medium transport mechanism 14, a print head control section 15, a carriage drive mechanism control section 16, a medium transport mechanism control section 17, an image processing processor. 18.

The carriage drive mechanism 13 includes a timing belt 131, a pulley 132, a motor (not shown), and the like. The pulley 132 is rotatably attached to the carriage 12, and the timing belt 131 reciprocates the carriage 12 in the main scanning direction (± x direction) via the pulley 132 by receiving the driving force from the motor (not shown). Can be moved.

The print head 11 is mounted on a carriage 12. The print head 11 has dot forming elements (that is, nozzles NZ _{1 to} NZ) as shown in FIG.
Z ₁₅ ) is 180 d in the sub-scanning direction (the y direction in FIG. 1).
15 pieces are arranged at a density of pi. In this embodiment, the nozzles are formed serially in the print head 11, but may be formed in an array in the case of a color inkjet printer, for example.

The carriage drive mechanism controller 16 controls the carriage drive mechanism 13 by sending a reciprocating timing signal TS and the like to the carriage drive mechanism 13. Further, the print head control unit 15 drives the print head 11 in accordance with the reciprocation of the carriage 12 in the main scanning direction.

The medium transport mechanism 14 receives the pitch feed amount data PTD from the medium transport mechanism control unit 17, and transports the medium 100 in the sub-scanning direction at a pitch feed amount PT corresponding to the pitch feed amount data PTD. Can be.

In FIG. 1, the medium transport mechanism 14 includes a medium transport roller 141, a motor (in this embodiment, a stepping motor 142), a medium transport auxiliary roller 143,
And a gear group 144. The driving force of the stepping motor 142 is transmitted to the medium transport roller 141 via the gear group 144, and is transmitted to the medium transport roller 141.
Transports the medium 100 in the sub-scanning direction (y direction) so as to be sandwiched between the medium 100 and the medium transport auxiliary roller 143.

In FIG. 1, the medium transport mechanism controller 17 includes a pitch feed reference amount generator 171, a register (change amount storage means) 172, a change amount generator 173, and an adder 17.
4 and a counter 175.

In this embodiment, the medium transport mechanism controller 17
Indicates that the media feed mechanism 14 outputs the pitch feed amount data PT four times.
With the transmission of D as one cycle, pitch feed amount data PTD obtained by adding data corresponding to the pitch feed change amount to data corresponding to the pitch feed reference amount U is sent. The register 172 stores information δ ₁ , corresponding to the pitch feed change amounts _{１ 1} , △ ₂ , _{３ 3} , △ ₄ , respectively.
δ ₂ , δ ₃ , δ ₄ are stored.

The change amount generating section 173 refers to the register 172 and generates data D _Δ for the pitch feed change amounts △ ₁ , △ ₂ , _{３ 3} , △ ₄ . On the other hand, pitch feed reference amount generating unit 171 generates data D _U for pitch feed reference amount U. And data _{D U} for the pitch feed reference quantity U, pitch feed variation _{△ 1, △ 2, △ 3} , △
The data D _Δ for the _fourth data is added by the adder 174. The medium transport mechanism controller 17 determines the result of this addition ( _DU
+ D _△ ) as the pitch feed amount PT, and
4 Here, the counter 175 determines that Σδ _i = δ
₁ + δ ₂ + δ ₃ + δ ₄ are counted, and the medium transport mechanism control unit 17 sets δ ₁ , δ ₂ ,.
δ ₃ and δ ₄ are selected.

The medium transport mechanism control section 17 may calculate the pitch feed amount data PTD for each pitch feed, and may send this to the medium transport mechanism 14 one pitch at a time. Needless to say, the pitch feed amount data PTD can be stored in a stack provided in the medium transport mechanism control unit 17, the medium transport mechanism 14, and the like before the pitch feed.

In this embodiment, the image processor 18
Controls the print head controller 15, the carriage driving mechanism controller 16, the medium transport mechanism controller 17, and the like. The print head control unit 15 and the carriage drive mechanism control unit 16 store the values δ ₁ , δ ₂ , δ ₃ , δ of the register 172.
You need to know ₄ . In this embodiment, the image processor 18 acquires these values and sends them to the print head control unit 15 and the carriage drive mechanism control unit 16. Of course, the present invention is not limited to this. For example, the printhead control unit 15 and the carriage drive mechanism control unit 16 may use the values δ ₁ ,
It is also possible to acquire controls according to the values of δ ₂ , δ ₃ , δ ₄ and perform control according to these values.

In this embodiment, the print data PD loaded on the printer 1 is stored in a buffer memory (not shown). The print data PD is called by the print head control unit 15. The print head controller 15, the print head 11, and is configured to output a driving signal PHD corresponding to the nozzles _NZ 1 _{~NZ 15.}

The operation of the printer 1 having the above configuration will be described below.

The pitch feed reference amount U is given by the following equation (ie,
The above equation (1)), U = N × (D / t). In this embodiment, t = 4, D = 1/18
0 inches (resolution is 180 dpi), U = 1
/ 48 inches.

[0052] Further, the pitch feed amount of change △ _i, the following equation (i.e., the above-mentioned formula _{(2)), △ i =} -δ i × (D / t) _{However, δ i: ≧ - (t} -2) , ≦ (t−2), 整数 δ _i = 0. In this embodiment, since t = 4, δ
_{As i} , -2, -1, 0, +1, +2 can be adopted, and Σ
Considering the condition of δ _i = 0, δ ₁ = 0, δ ₂ = + 2, δ
₃ = −1, δ ₄ = −1. Therefore, _{１ 1} =
0 (inch), △ ₂ = −1 / 320 (inch), _{３ 3} =
Δ ₄ = + 1/720 (inch).

FIGS. 2A to 2D show drop positions of dots that are continuous in the sub-scanning direction when ink droplets are dropped on a medium by four consecutive pitch feeds. I have. In FIG. 2A, after the first pitch feed,
Black droplets P ₁ and P ₅ indicate positions where ink droplets are deposited from the nozzles NZ ₁₅ and NZ ₁₄ .

In the second pitch feed, the medium transport mechanism control section 17 sends the pitch transport amount data PTD corresponding to (U + △ ₂ ) to the medium transport mechanism 14. Here, the pitch feed amount is U + △ ₂ (that is, 1 / 48−
The printhead controller 15 drives the stepping motor 142 so as to make 1/320 (inch), and sends a predetermined drive signal to each nozzle of the printhead 11. In FIG. 2 (B), shown in this case, the dripping position of ink droplets from the nozzle _{NZ 11} by a black circle _{P 2.}

In the third pitch feed, the medium transport mechanism control section 17 sends the pitch transport amount data PTD corresponding to (U + △ ₃ ) to the medium transport mechanism 14. Here, the pitch feed amount is U + △ ₃ (that is, 1/48 +
The printhead control unit 15 drives the stepping motor 142 so as to make 1/720 (inch), and sends a predetermined drive signal to each nozzle of the printhead 11. In FIG. 2 (C), shown in this case, the dripping position of ink droplets from the nozzles NZ ₇ by black circles _{P 3.}

In the fourth pitch feed, the medium transport mechanism control section 17 sends the pitch transport amount data PTD corresponding to (U + △ ₄ ) to the medium transport mechanism 14. Here, the pitch feed amount is U + △ ₄ (that is, 1/48 +
The printhead control unit 15 drives the stepping motor 142 so as to make 1/720 (inch), and sends a predetermined drive signal to each nozzle of the printhead 11. In FIG. 2 (D), shown in this case, the dripping position of ink droplets from the nozzle NZ ₃ by black circles _{P 4.} Also, P ₁ , P
The setting positions of ₂ , P ₃ , P ₄ , and P ₅ (original ink droplet deposition positions) are indicated by dotted lines.

FIG. 2 shows a case where the actual pitch feed amount is smaller than the original pitch feed amount L by δ _{L at} each pitch feed, as shown in FIG. 6 (prior art). It is.

[0058] In FIG. 6, the error between adjacent dots (between dripping position) is maximum was 3Deruta _L, in the embodiment of FIG. 2, at most 2.delta. _L. Therefore, in this embodiment, image unevenness is less likely to occur than in the conventional method of FIG.

FIG. 3 shows a case where the actual pitch feed amount is larger than the original pitch feed amount L by δ _{L in} each pitch feed. Also in this case, as in FIG. 2, δ ₁ = 0, δ ₂ = + 2, δ ₃ = −1,
Since δ ₄ = −1, △ ₁ = 0 inch, △ ₂ = −
1/320, _{３ 3} = △ ₄ = + ／ 720 inch.
In FIG. 3 (A), the first pitch feeding, shows the dripping position of ink droplets from the nozzle _{NZ 15} and _{NZ 14} Metropolitan by a black circle _P 1, _{P 5,} FIG. 3 (B), (C) , ( D)
Black circles P ₂ , P ₃ , and P ₄ indicate positions where ink droplets are deposited from the nozzles NZ ₁₁ , NZ ₇ , and NZ _{3 in the} second, third, and fourth pitch feeds. In the case of Figure 3, since the error between adjacent dots is the largest at 2.delta. _L, image unevenness is less likely to occur even in this case.

In the above embodiment, the error of the pitch feed amount has been described as being the same for each pitch feed, but in general, the pitch feed error differs for each pitch feed. In such a case, the settings of δ ₁ , δ ₂ , δ ₃ , δ ₄ can be changed. If the number of print heads 11 is set to 15 or more (for example, 18), the values of δ ₁ , δ ₂ , δ ₃ , δ ₄ can be changed during printing.

[0061]

According to the present invention, a group of dot rows is printed in a different order from the arrangement of the dot rows in the main scanning direction, so that adjacent dots (ink droplets) come close to each other (or Overlapping) or adjacent dots are not far apart. Therefore, deterioration of image quality can be prevented or improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration example of a printer according to the invention.

2A and 2B are diagrams illustrating an operation when an error is smaller than an original pitch feed amount, and FIG. 2A is a diagram illustrating a position where a first ink droplet is deposited in four consecutive pitch feeds. (B) is a diagram showing a second ink droplet deposition position, (C) is a third ink droplet deposition position, and (D) is a fourth ink droplet deposition position. FIG.

3A and 3B are diagrams illustrating an operation when an error is greater than an original pitch feed amount, and FIG. 3A is a diagram illustrating a first ink droplet deposition position in four consecutive pitch feeds. (B) is a diagram showing a second ink droplet deposition position, (C) is a third ink droplet deposition position, and (D) is a fourth ink droplet deposition position. FIG.

FIG. 4 is an explanatory view schematically illustrating a conventional inkjet printer 11 that performs printing in an interlaced mode.

FIGS. 5A and 5B are diagrams illustrating the principle of printing by a conventional interlace method, and FIG. 5A is a diagram illustrating the principle of ink dropping from each nozzle during a medium conveyance stop period; FIG. 4D is a diagram showing a principle drop position of ink from each nozzle during a transport stop period after one pitch feed of the medium.

6A and 6B are diagrams illustrating a conventional technique when an error is smaller than an original pitch feed amount, and FIG. 6A is a diagram illustrating a first ink droplet deposition position in four consecutive pitch feeds. , (B) is a diagram showing a second ink droplet deposition position, (C) is a third ink droplet deposition position, (D) is a fourth ink droplet deposition It is a figure showing a position.

7A and 7B are diagrams for explaining a conventional technique in which an error is larger than an original pitch feed amount, and FIG. 7A is a diagram illustrating a first ink droplet deposition position in four consecutive pitch feeds. , (B) is a diagram showing a second ink droplet deposition position, (C) is a third ink droplet deposition position, (D) is a fourth ink droplet deposition It is a figure showing a position.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printer 11 Print head 12 Carriage 13 Carriage drive mechanism 131 Timing belt 132 Pulley 14 Medium conveyance mechanism 141 Medium conveyance roller 142 Stepping motor 143 Medium conveyance auxiliary roller 144 Gear group 15 Printer head control part 16 Carriage drive mechanism control part 17 Medium conveyance mechanism Control unit 171 Pitch feed reference amount generation unit 172 Register 173 Change amount generation unit 174 Adder 175 Counter 18 Image processing processor

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Claims (6)

[Claims] A print head in which a plurality of dot forming elements are arranged at predetermined intervals in a sub-scanning direction; a carriage on which the print head is mounted; and a carriage driving mechanism for reciprocating the carriage in the main scanning direction. A medium transport mechanism that transports a print medium at a predetermined pitch feed amount in the sub-scanning direction; a print head control unit that drives the print head; a carriage drive mechanism control unit that controls the carriage drive mechanism; A medium transport mechanism control unit that sends pitch feed amount data in units of one pitch to the mechanism and controls the medium transport mechanism. The dot pitch P in the sub-scanning direction of the image to be printed is provided.
Where D / t, where t: an integer of 3 or more, and D: the interval between dot forming elements. In the interlaced printer, the medium transport mechanism control unit controls the medium transport mechanism to transmit t times of pitch feed amount. Assuming that data transmission is one cycle, the following equation (1)
And the medium corresponding to the pitch feed reference amount U represented by the following formula (2) is added to the data corresponding to the change amount _ｉi represented by the following equation (2). An interlaced printer, characterized in that the transport mechanism control unit is provided with a change amount storage means for storing information δ _i corresponding to the change amount △ _i . U = N × (D / t) (1) where N: the number of dot forming elements having a relationship of “prime” with each other D: interval of dot forming elements Δ _i = −δ _i × (D / t) (2) where i: 1, 2,..., T δ _i : an integer ≧ − (t−2), ≦ (t−2), ， δ _i = 0 2. The change amount storage means of the information δ _i ,
δ _1, δ _{2, ···,} characterized in that it is a register for storing a value of [delta] _t, interlaced printer according to claim 1. 3. The interlaced printer according to claim 1, wherein the medium transport mechanism control unit has a counter that stores a value of Σδ _i . 4. The register has a number of storage units τ smaller than t, and stores δ ₁ , δ ₂ ,.
4. The register according to claim 2, wherein τ information of... _Δt is stored. 5. The method according to claim 1, wherein the number of dot forming elements formed on the print head is N.
The interlaced printer according to any one of the above. 6. The dot pitch P in the sub-scanning direction of an image printed by a print head in which dot forming elements are arranged at predetermined intervals in the sub-scanning direction is D / t, where t is an integer of 3 or more. : In the interlaced printing method in which the intervals of the dot forming elements are expressed, the following formula is used for the pitch feed reference amount U expressed by the following equation (1) for each group of continuous t rows among the dot rows in the main scanning direction. (2) The print medium is transported by the pitch feed amount to which the change amount △ _i is added, and the group of t rows is printed in a different order from the arrangement order of the dot rows in the main scanning direction. Interlaced printing method. U = N × (D / t) (1) where N: the number of dot forming elements having a “prime” relationship with t D: interval of dot forming elements Δ _i = −δ _i × (D / t) (2) where, i: 1, 2,..., T δ _i : an integer ≧ − (t−2), ≦ (t−2), Σδ _i = 0