JP2001150705A - Printing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable highly fine printing. SOLUTION: The apparatus includes a carriage-driving part for driving to move a carriage in a horizontal scanning direction, a driving pulse generating part for generating driving pulses, and a nozzle head mounted on the carriage and having a plurality of nozzle arrays for discharging ink drops on the basis of the driving pulses. A speed in the horizontal scanning direction of the carriage when ink drops are discharged from each of the nozzle arrays is made equal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a printing apparatus.

[0002]

2. Description of the Related Art In general, in a serial printer such as an ink jet printer, a recording head scans a printing paper to perform printing. The recording head is fixed to the carriage and moves with the carriage. The carriage is driven by a DC motor. The driving method is as follows.

First, a timing belt is tensioned by a pulley fixed to a rotating shaft of a DC motor and a driven vehicle paired with the pulley so as to have a predetermined tension, and the carriage is attached to the timing belt. Is configured. Thereby, the carriage is driven so as to move in the main scanning direction by the rotation of the DC motor.

When the carriage is moving at a constant speed,
That is, printing is performed when the DC motor is rotating at a constant speed.

[0005]

However, the DC motor has a torque fluctuation, and this torque fluctuation occurs p times during one rotation of the DC motor, where p is the number of poles of the DC motor.

For this reason, in a color serial printer using a DC motor for driving the carriage, the speed of the carriage (ie, D
(The speed of the C motor) fluctuates and periodic vertical stripes are generated in the main scanning direction, and there is a problem that high-definition printing cannot be performed.

The present invention has been made in view of the above circumstances, and has as its object to provide a printing apparatus capable of performing high-definition printing.

[0008]

A printing apparatus according to the present invention is provided with a carriage driving section for driving a carriage to move in a main scanning direction, a driving pulse generating section for generating a driving pulse, and mounted on the carriage. A nozzle head having a plurality of nozzle arrays that eject ink droplets based on drive pulses, wherein the speed of the carriage in the main scanning direction when ejecting ink droplets from each of the nozzle arrays is the same. The printing apparatus is characterized in that the printing apparatus is configured to be configured as follows.

The nozzle head may have a black nozzle row for discharging black ink droplets and at least a first and a second nozzle row for discharging ink drops of different colors. good.

The distance between the nozzle rows of the first nozzle row and the second nozzle row is an integral multiple of the distance the carriage moves during one cycle Tv of the speed variation of the carriage. Is preferred.

The time T from when ink droplets are ejected from one of the first and second nozzle arrays to when ink droplets are ejected from the other nozzle array is one cycle of the speed variation of the carriage. It is preferable to be configured to be an integral multiple of Tv.

The carriage driving section includes a motor, a pulley mounted on a rotating shaft of the motor, and a timing belt driven by the pulley to move the carriage in the main scanning direction. You may.

The distance L between the nozzle rows of the first nozzle row and the second nozzle row and the pitch circle length Lp of the pulley are defined by p as the number of poles of the carriage motor and n as a positive number. When an integer is set, the configuration may be such that L = n · Lp / p is satisfied.

It is preferable that the first and second nozzle arrays are configured to eject ink droplets of a color that affects the image quality due to color superposition.

[0015] Incidentally, the nozzle row distance L between the first nozzle row and the second nozzle array, the pitch p ₁ of the timing belt, when the m is a positive integer, L = m · p ₁ May be configured to satisfy the following.

It is preferable that the first nozzle row discharges magenta ink droplets and the second nozzle row discharges cyan ink droplets.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a printing apparatus according to the present invention will be described with reference to the drawings. The printing apparatus of this embodiment is an ink jet printer, and FIG. 6 shows a schematic configuration of the ink jet printer.

This ink jet printer includes a paper feed motor (hereinafter also referred to as a PF motor) 1 for feeding paper,
A paper feed motor driver 2 for driving this paper feed motor 1
, A carriage 3, a carriage motor (hereinafter also referred to as a CR motor) 4 for driving the carriage 3, and a CR motor driver 5 for driving the carriage motor 4
, A DC unit 6, a pump motor 7 for controlling suction of ink to prevent clogging, a pump motor driver 8 for driving the pump motor 7, and a carriage 3
9 which is fixed to the head and ejects ink to the printing paper 50
And a head driver 10 for driving and controlling the head 9
And a linear encoder 11 fixed to the carriage 3
And a code plate 12 having slits formed at predetermined intervals,
A rotary encoder 13 for the PF motor 1 and a current sensor 14 for detecting a current flowing through the carriage motor 4
A paper detection sensor 15 for detecting the end position of the paper being printed, and a CPU 16 for controlling the entire printer.
A timer IC 17 for periodically generating an interrupt signal to the CPU 16, an interface unit (hereinafter also referred to as an IF) 19 for transmitting and receiving data to and from the host computer 18, and a transmission from the host computer 18 via the IF 19. An ASIC 20 for controlling a printing resolution, a driving waveform of the head 9, and the like based on the received printing information;
PROM 21, RAM 22, and EE used as work areas and program storage areas for CPU 20 and CPU 16.
PROM 23 and platen 2 supporting paper 50 being printed
5, a transport roller 27 driven by the PF motor 1 to transport the printing paper 50, a pulley 30 attached to the rotation shaft of the CR motor 4, and a timing belt 31 driven by the pulley 30. I have.

The DC unit 6 drives and controls the paper feed motor driver 2 and the CR motor driver 5 based on control commands sent from the CPU 16 and outputs of the encoders 11 and 13. Each of the paper feed motor 1 and the CR motor 4 is constituted by a DC motor.

FIG. 7 shows a configuration around the carriage 3 of the ink jet printer.

The carriage 3 is connected to the carriage motor 4 via a pulley 30 by a timing belt 31 and is driven by a guide member 32 to move parallel to the platen 25. On the surface of the carriage 3 facing the printing paper, a recording head 9 including a nozzle array for discharging black ink and a nozzle array for discharging color ink is provided. Each nozzle receives ink supplied from an ink cartridge 34 to perform printing. Prints characters and images by ejecting ink droplets on paper.

In the non-printing area of the carriage 3, a capping device 35 for sealing the nozzle opening of the recording head 9 during non-printing and a pump unit 36 having a pump motor 7 shown in FIG. 6 are provided. I have. When the carriage 3 moves from the print area (no-load area) to the non-print area (load area), the capping device 35 moves upward by contacting a lever (not shown) to seal the head 9.

When clogging occurs in the nozzle opening row of the head 9 or when the cartridge 34 is replaced or the like,
When the ink is forcibly ejected from the pump unit, the pump unit is operated while the head 9 is sealed, and the ink is sucked out from the nozzle opening row by the negative pressure from the pump unit. Thus, dust adhering in the vicinity of the nozzle opening row is cleaned, and the bubbles of the head 9 are discharged to the cap 37 together with the ink.

Next, the configuration of the linear encoder 11 mounted on the carriage 3 is shown in FIG. The encoder 11 includes a light emitting diode 11a and a collimator lens 11
b and a detection processing unit 11c. The detection processing unit 11c includes a plurality of (four) photodiodes 11d, a signal processing circuit 11e, and two comparators 11fA, 1fA.
1fB.

When a voltage Vcc is applied to both ends of the light emitting diode 11a via a resistor, light is emitted from the light emitting diode 11a. This light is made parallel by the collimator lens 11b and passes through the code plate 12. The code plate 12 has a configuration in which slits are provided at predetermined intervals (for example, 1/180 inch).

The parallel light that has passed through the code plate 12 passes through a fixed slit (not shown) and passes through each photodiode 11d.
And is converted into an electric signal. The electric signals output from the four photodiodes 11d are applied to the signal processing circuit 11
The signal is processed in e. The signals output from the signal processing circuit 11e are compared in the comparators 11fA and 11fB, and the comparison result is output as a pulse. Pulse EN output from comparators 11fA and 11fB
CA and ENC-B are outputs of the encoder 11.

The phases of pulse ENC-A and pulse ENC-B differ by 90 degrees. When the CR motor 4 is rotating forward, that is, when the carriage 3 is moving in the main scanning direction, the pulse ENC-A is changed to the pulse ENC as shown in FIG.
When the CR motor 4 is rotating in the reverse direction by 90 degrees from that of the pulse ENC-B as shown in FIG.
The encoder 4 is configured such that the phase of A is delayed by 90 degrees from the pulse ENC-B. One cycle T of the pulse is equal to the slit interval of the code plate 12 (for example, 1 /
180 inches), which is equal to the time during which the carriage 3 moves through the slit interval.

On the other hand, the rotary encoder 13 for the PF motor 1 has the same configuration as the linear encoder 11 except that the code plate is a rotating disk that rotates in accordance with the rotation of the PF motor 1. In the ink jet printer, the slit interval of a plurality of slits provided on the code plate of the encoder 13 for the PF motor 1 is 1 /.
180 inches, and the paper is fed by 1/1440 inch when the PF motor 1 rotates by the slit interval.

Next, the paper detection sensor 15 shown in FIG.
Will be described with reference to FIG. In FIG. 10, the paper 5 inserted into the paper feed slot 61 of the printer 60 is shown.
0 is the paper feed roller 6 driven by the paper feed motor 63
4 to the printer 60. Printer 6
The leading end of the paper 50 fed into the area 0 is detected by, for example, an optical paper detection sensor 15. This paper detection sensor 1
The paper 50 whose leading end is detected by the paper feed roller 65 and the free roller 6 driven by the PF motor 1
6, the paper is fed.

Subsequently, printing is performed by dropping ink from a recording head (not shown) fixed to the carriage 3 moving along the carriage guide member 32. When the paper is fed to a predetermined position,
The end of the printed paper 50 is detected by the paper detection sensor 15. The gear 67c is driven by the gear 67a driven by the PF motor 1 via the gear 67b, whereby the paper discharge roller 68 and the free roller 69 are driven to rotate, and the paper 50 on which printing has been completed is discharged to the paper discharge port. It is discharged from 62 to the outside.

Next, the head driver 10 for forming ink droplets will be described with reference to FIG. The head driver 10, the interface unit from the host computer 18 (hereinafter, also referred to as IF) and the receiving buffer 10a ₁ for temporarily storing the print data or the like including a multivalue gradation information sent via the 19, various data RAM to store the data
And 10a _2, an output buffer 10a _3, a ROM10b storing routines, etc. for various types of data processing, CPU
A driving signal generating circuit 10d for generating a driving signal (COM) for each piezo element of the print head 9 described later, and a piezo element driving circuit 10f And an interface 10e for transmission to the

[0032] The host computer 18, in this embodiment, since the print data after binarization processing has been performed is sent, the head driver 10, after stored the print data in the reception buffer 10a ₁ once expanded data to an output buffer 10a ₃ in accordance with the arrangement of the nozzle array of the print head 9, through the interface 10e this
It is enough to output it. The print head 9 is, for example, each color 4
Since eight nozzles are provided, one of the print heads 9
After preparing the dot pattern data corresponding to scan of the output buffer 10a _3, the dot pattern data, and outputs via the interferon over scan 10e. The print data developed as dot pattern data is composed of, for example, one bit as gradation data for each nozzle, as will be described later.
Respectively correspond to dot formation.

Further, in order to clearly explain the reason for forming ink droplets by the head driving unit, the principle of ink ejection, the principle of forming ink droplets, and the piezo element driving circuit will be described in order.

First, the principle of ink ejection will be described.

A mechanism for discharging ink and forming dots will be described. FIG. 12 is an explanatory diagram showing a schematic configuration inside the print head 9, and FIG. 13 is a schematic diagram showing a state in which ink is ejected by expansion and contraction of the piezo element PE. When the ink cartridge 34 is mounted on the carriage 3, as shown in FIG. 12, the ink in the ink cartridge is sucked out through the introduction tube 34 a by utilizing the capillary phenomenon, and the print head provided at the lower portion of the carriage 3. 9 for each color head.

In the present embodiment, the head of each color is provided with 48 nozzles for each color, and is one of the electrostrictive elements as a pressure generating element for each nozzle and has excellent responsiveness. A piezo element PE is disposed. As shown in FIG. 13A, the piezo element PE is provided at a position in contact with an ink passage 9a for guiding ink to a nozzle. As is well known, the piezo element PE is an element that distorts the crystal structure due to the application of a voltage and converts electro-mechanical energy very quickly. In the present embodiment, by applying a voltage having a predetermined time width between the electrodes provided at both ends of the piezo element PE, the piezo element PE contracts by the voltage application time as shown in FIG. , Ink passage 9a
Is changed. As a result, the volume of the ink passage 9a contracts in accordance with the contraction of the piezo element PE, and the ink corresponding to the contraction becomes particles Ip, and is ejected at a high speed from the tip of the nozzle. The ink particles Ip are applied to the platen 2
Printing is performed by soaking into the sheet 50 attached to the sheet 5.

Next, the principle of ink droplet formation will be described.

In this embodiment, 48 nozzles Nz for each color
Have the same inner diameter. Such a nozzle N
Two types of dots having different diameters can be formed using z. This principle will be described. FIG. 14 is an explanatory diagram schematically showing a relationship between a driving waveform of the nozzle Nz when the ink is ejected and the ejected ink. FIG.
When the voltage from the intermediate potential to the low potential side is rapidly applied as shown in the section d1 by using the drive waveform shown by the solid line in (a), the state in which the ink is largely depressed inward as shown in FIG. Become.

Thereafter, when the voltage applied to the piezo element PE is made positive (section d3), ink is ejected based on the principle described above with reference to FIG. 13 (FIG. 14C,
(D)).

Finally, the piezo element driving circuit will be described.

FIG. 15 is a block diagram showing the internal configuration of the piezo element drive circuit 10f. As shown, the piezo element driving circuit 10f includes shift registers 253A to 253N, latch elements 254A to 254N, and level shifters 255A to 255 corresponding to the respective nozzles of the print head 9.
5N, switch elements 256A to 256N, piezo element 2
57A to 257N. The print data is
Each nozzle is composed of 1-bit data. Then, 1-bit data for all nozzles is input to the shift registers 253A to 253N within one recording cycle. That is, 1-bit data for all nozzles is serially transferred to the shift registers 253A to 253N. And
For example, when the bit data applied to each of the switch elements 256A to 256N configured as analog switches is "1", the drive signal (COM) sent from the drive signal generation circuit 10d via the interface 10e is used to drive the piezo element. Piezo elements 257A to 257 as signals
N, and each of the piezo elements 257A to 257N is displaced according to the signal waveform of the drive signal (COM). Conversely, when the bit data applied to each of the switch elements 256A to 256N is “0”, each of the piezo elements 257A to 257A
The drive signal (COM) to 7N is cut off, and each of the piezo elements 257A to 257N holds the previous charge.

Each 1-bit print data is transferred to the switch element 2
The specific configuration given to 56 etc. will be narrowed. First, the output buffer stores the 1
Bit print data (D1) is stored. Here, D1 is a pulse selection signal. The 1-bit print data is supplied to the switch elements 256 corresponding to the respective nozzles of the print head 9 within one recording cycle. Specifically, the number of nozzles of the print head 9 is n, and the print data of the first nozzle at a certain position in the sub-scanning direction is (D1
1) When the print data of the second nozzle is represented as (D12), the shift register 253 stores the data (D11, D1) of the pulse selection signal D1 for all nozzles.
2, D13,. . . D1n) is PTS (Print Timing S)
ingal) Serial input in synchronization with the signal. The PTS signal is sent from the DC unit 6, and this PTS is an output signal of the linear encoder 11 (for example, ENC-
A), the cycle immediately before the signal ENC-A is detected (for example, a cycle corresponding to 1/180 inch)
Is output from the DC unit 6 as a pulse signal having a period of, for example, 1/16 (for example, a period corresponding to 1/2880 inch) (see FIGS. 16A and 16B). Note that the PTS may be output as a pulse signal having a cycle of 1/32 of the sum of the immediately preceding cycle and the previous cycle.

Based on the above description, the head driver 1
A mechanism for recording on the paper surface 50 by causing the carriage 3 to scan in the main scanning direction while ejecting ink droplets in the direction of gravity based on the PTS from the DC unit 6 will be briefly described below. The drive signal generation circuit 10d generates a drive waveform for forming an ink droplet, that is, a drive signal (COM), and generates a drive signal (COM) inside the piezoelectric element drive circuit 10d.
By comparing the bit data applied to each of the switch elements 256A to 256N inside f with the PTS from the DC unit 6 and transferring the applied voltage shown in FIG. 14A to each of the piezo elements 257A to 257N, The carriage is moved at a constant speed in the main scanning direction while ejecting ink droplets downward in the direction of gravity, so that the ink droplets land at a desired position on the paper surface 50.

However, if the speed of the carriage 3 fluctuates while the print head 9 is driven based on the PTS signal, ink droplets ejected from different nozzles of the print head 9 will be at the same position on the paper. It is common that they do not land. This will be described with reference to FIG.

Now, when the nozzle 14a of the print head 9 passes the point P, for example, a cyan ink droplet is ejected at a predetermined ejection pressure based on the PTS, and the nozzle 1 of the print head 9 is ejected.
Consider a case in which, when 4b passes through the point P, magenta ink droplets are ejected at the above-mentioned predetermined ejection pressure based on the PTS, and printing is performed on the same point on the printing paper.

Since the ink droplets are ejected from the nozzles 14a and 14b at a predetermined ejection pressure, the ejection speed 80 of the ink droplet in a direction perpendicular to the direction in which the print head 9 moves is a predetermined value. The combined speed of this speed 80 and the speed 82 of the print head 9 when the nozzle 14a passes through the point P is the speed at which the ink droplets are ejected from the nozzles 14a. The ink droplet lands at the point A. Then, the print head 9 moves horizontally (to the right in FIG. 17), and the speed 85 of the print head 9 when the nozzle 14b passes through the point P is changed so that the nozzle 14a passes through the point P due to the speed fluctuation of the carriage 3. Speed 82 is generally different. Therefore, when the nozzle 14b passes through the point P, the ejection speed of the magenta ink droplet ejected from the nozzle 14b is a combined speed 87 of the speed 80 and the speed 85, and the above-described magenta ink droplet is the combined speed 87 of the combined speed 87. It lands at the position of point B on the printing paper on the extension line. Therefore, when the speed of the carriage 3 fluctuates, the cyan ink droplet ejected from the nozzle 14a and the nozzle 1
Generally, it is difficult to land the magenta ink droplet ejected from 4b on the same point on the printing paper.

Therefore, the printing apparatus according to the present embodiment solves the above-described problem. The speed of the carriage 3 in the main scanning direction at the moment when, for example, a cyan ink droplet is ejected from the nozzle 14a, and the speed of the nozzle 14b For example, the ink droplets are ejected at an ejection timing such that the speed of the carriage 3 in the main scanning direction at the moment when the magenta ink droplet is ejected becomes equal.

[0048] For example, when the speed of the carriage 3 fluctuates around the average speed Ve as shown in FIG. 1, for example, when the ink droplets are ejected from the nozzle 14a at time t _0, the ink droplets from the nozzle 14b discharge timing to become, for example, the time _{t 1} and watch _{t 2,} and the like. That is, a nozzle (for example, the nozzle 14a) which discharges an ink droplet to be superimposed at a position where the ink droplet lands after a certain nozzle (for example, the nozzle 14a) discharges the ink droplet
b) Time (timing) T until the ink droplet is ejected
Is the period T of the speed fluctuation of the carriage 3 as shown in FIG.
If it is an integral multiple of v, no color shift will occur.

When it is considered that the speed fluctuation of the carriage 3 consists only of the speed fluctuation of the carriage motor 4, the number of poles of the carriage motor 4 is p, and the pulley 30 attached to the rotation shaft of the carriage motor 4 drives the timing belt 31.
Is the effective diameter length (that is, the pitch circle length) of the carriage 3, the cycle Tv of the speed fluctuation of the carriage 3 is Tv = Lp / (p
Ve).

Therefore, in order to prevent color misregistration, if n is a positive integer, the configuration may be such that T = n.Tv = n.Lp / (p.Ve).

If the distance between the nozzle rows for ejecting ink droplets to be superimposed is L, then L = T · Ve. Therefore, the distance L between the nozzle rows of the nozzles that eject the ink droplets to be color-overlaid may be configured to satisfy L = n · Lp / p.

For example, consider a six-color head 9 as shown in FIG. This head 9 has six nozzle rows 9a, 9b, 9
c, 9d, 9e and 9f, and each nozzle row 9i
(I = a,... F) has a configuration in which a plurality of nozzles 14 are arranged in one row, and the corresponding nozzles are arranged on the same straight line. The nozzle row 9a discharges yellow (Y) ink drops, the nozzle row 9b discharges light magenta (LM) ink drops, the nozzle row 9c discharges magenta (M) ink drops, Row 9d discharges light cyan (LC) ink drops, nozzle row 9e discharges cyan (C) ink drops, and nozzle row 9f discharges black (K) ink drops. I have.

In the six-color head shown in FIG. 2, the inter-row distance L of each nozzle row satisfies L = n · Lp / p. With this configuration, it is possible to perform high-definition printing without causing landing displacement.

Incidentally, yellow (Y) and light magenta (L
M) The light cyan ink droplets are not noticeable to human eyes even if they are slightly misaligned. For this reason, at least the nozzle array 9c that ejects magenta (M) ink droplets
And a nozzle array 9e for ejecting cyan (C) ink droplets
If the distance L ₁ between the nozzle rows between the nozzles is configured to satisfy L ₁ = n · Lp / p, high-definition printing can be performed.

Also, in the case of the four-color head 9 as shown in FIG. 3, the distance L between the nozzle rows may be configured to satisfy L = n · Lp / p, or the magenta (M) color may be used. The configuration may be such that only the distance between the nozzle row that discharges and the nozzle row that discharges cyan (C) satisfies the above expression.

The same applies to a six-color head in which the nozzles are arranged in a staggered manner as shown in FIG.

[0057] For this way the nozzle row separation distance L that is determined, the influence of the velocity fluctuation due to the pitch p ₁ of the timing belt 31 by appropriately determining the pitch p ₁ of the timing belt 31 also be removed it can. This will be described. The pitch p of the timing belt 31
₁ means the pitch of the convex portions provided to engage with the pulley 30 as shown in FIG. Thus, the pitch _{p 1} of the timing belt 31, timing belt 31
And the pulley 30 are engaged with each other,
, That is, a value obtained by dividing the pitch circle length Lp by the number Z of teeth of the pulley 30 and p ₁ = Lp / Z.

Meanwhile, the carriage 3 according to the pitch _{p 1}
The speed variation Tvp of Tvp = Lp / (Z · Ve) = p
₁ / Ve. Therefore, in order to color misregistration does not occur, when the m is a positive integer, the timing T for ejecting ink droplets to be color superposition may be configured so as to satisfy T = m · Tvp = mp 1 / Ve .

On the other hand, the distance L between the nozzle rows for discharging the ink droplets to be superposed is L = T · Ve. Therefore, L
= T · Ve = m · p ₁ , color misregistration due to the influence of the pitch p ₁ of the timing belt 31 can be prevented.

In the above description, the pulley 30
Is determined when the effective diameter length (pitch circle length) Lp is determined in advance, but when the distance L between nozzle rows is determined in advance, as shown in FIG. The effective diameter length Lp may be determined so as to satisfy Lp = (Lp) / n.

If the diameter of the pitch circle of the pulley 30 is Dp, then Lp = π · Dp. Therefore, the diameter Dp of the pitch circle of the pulley 30 may be configured to satisfy Dp = (L · p) / (n · π).

In the above-described embodiment, the carriage 3 is driven so as to move in the main scanning direction by the carriage driving unit including the carriage motor 4, the pulley 30, and the timing belt 31, but the present invention is not limited to this. However, the present invention is not limited to this, and the carriage may be driven by a carriage driving unit having another configuration. Also in this case, if the speed of the carriage 3 in the main scanning direction when ejecting ink droplets from each of the nozzle rows is made equal, high-definition printing can be performed.

The distance between the nozzle arrays may be an integral multiple of the distance the carriage 3 moves during one cycle Tv of the speed fluctuation of the carriage 3.

[0064]

As described above, according to the present invention, it is possible to prevent the occurrence of color misregistration as much as possible, and to perform high-definition printing.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between ink droplet ejection timing and carriage speed fluctuation according to an embodiment of the present invention.

FIG. 2 is a diagram showing a nozzle arrangement of a six-color head according to the present invention.

FIG. 3 is a diagram showing a nozzle arrangement of a four-color head according to the present invention.

FIG. 4 shows a nozzle according to the invention in which the nozzles are arranged in a staggered arrangement.
FIG. 3 is a diagram showing a nozzle arrangement of a color head.

FIG. 5 is a diagram illustrating a relationship between a carriage and a pulley.

FIG. 6 is a block diagram illustrating a configuration of a printing apparatus according to the present invention.

FIG. 7 is a perspective view showing a configuration around a carriage.

FIG. 8 is a schematic diagram showing a configuration of a linear encoder.

FIG. 9 is a waveform diagram of an output pulse of an encoder.

FIG. 10 is a schematic perspective view of the printer illustrating the position of a paper detection sensor.

FIG. 11 is a block diagram showing a specific configuration of a head driver according to the present invention.

FIG. 12 is a schematic configuration diagram around a feed pipe of a print head.

FIG. 13 is an explanatory view showing the principle of ejecting ink droplets by expansion and contraction of a piezo element.

FIG. 14 is a schematic diagram illustrating the relationship between a drive signal applied to a piezo element and ejection of ink droplets.

FIG. 15 is a block diagram showing a specific configuration of a piezo element driving circuit.

FIG. 16 is a timing chart illustrating a PTS occurrence situation.

FIG. 17 is a view for explaining the speed of a head and the landing position of an ink droplet.

[Explanation of symbols]

 1 Paper feed motor (PF motor) 2 Paper feed driver 3 Carriage 4 Carriage motor (CR motor) 5 Carriage motor driver (CR motor driver) 6 DC unit 7 Pump motor 8 Pump motor driver 9 Recording head 10 Head driver 11 Linear encoder DESCRIPTION OF SYMBOLS 12 Code board 13 Encoder (lolita-type encoder) 14 Nozzle 15 Paper detection sensor 16 CPU 17 Timer IC 18 Host computer 19 Interface unit 20 ASIC 21 PROM 22 RAM 23 EEPROM 25 Platen 30 Pulley 31 Timing belt 32 Guide member of carriage motor 34 Ink Cartridge 35 Capping device 36 Pump unit 37 Cap 50 Recording paper

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiroaki Tojo 3-5-5 Yamato, Suwa-shi, Nagano F-term in Seiko Epson Corporation (reference) 2C056 EA07 EA11 EB11 EB37 ED07 EE02 EE09 FA10 HA22 HA38 2C480 CA11 CA32 DA01 EA02 EC04

Claims (9)

[Claims] 1. A carriage driving unit for driving a carriage to move in a main scanning direction; a driving pulse generating unit for generating a driving pulse; and being mounted on the carriage and ejecting ink droplets based on the driving pulse. A printing head comprising: a nozzle head having a plurality of nozzle arrays; and a configuration in which the speed of the carriage in the main scanning direction when ejecting ink droplets from each of the nozzle arrays is the same. Printing device. 2. The nozzle head according to claim 1, wherein the nozzle head has a black nozzle array for ejecting black ink droplets, and at least first and second nozzle arrays for ejecting ink droplets of different colors. The printing device according to claim 1, wherein 3. A distance between nozzle rows of the first nozzle row and the second nozzle row is an integral multiple of a distance traveled by the carriage during one cycle Tv of speed variation of the carriage. 3. The printing apparatus according to claim 2, wherein the printing apparatus is configured. 4. A time period T from when an ink droplet is ejected from one of the first and second nozzle lines to when an ink droplet is ejected from the other nozzle line is determined by a speed variation of the carriage. 3. The printing apparatus according to claim 2, wherein the printing apparatus is configured to be an integral multiple of one cycle Tv. 5. The carriage driving section includes a motor, a pulley mounted on a rotating shaft of the motor, and a timing belt driven by the pulley to move the carriage in a main scanning direction. The printing device according to claim 2, wherein: 6. A distance L between nozzle rows of the first nozzle row and the second nozzle row, and a pitch circle length Lp of the pulley, wherein the number of poles of the carriage motor is p, and n is a positive number. 6. The printing apparatus according to claim 5, wherein, as an integer, L = n.Lp / p is satisfied. 7. A distance between the nozzle rows of the first nozzle row and the second nozzle row L, the pitch p ₁ of the timing belt, when the m is a positive integer, L = m · p ₁ 6. The printing apparatus according to claim 5, wherein the printing apparatus is configured to satisfy the following. 8. The printing apparatus according to claim 2, wherein the first and second nozzle arrays discharge ink droplets of a color that affects image quality due to color superposition. . 9. The printing apparatus according to claim 8, wherein the first nozzle row discharges magenta ink droplets, and the second nozzle row discharges cyan ink droplets.