JP2007105970A - Inkjet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording apparatus which delivers ink droplets at an appropriate timing and makes recording even when a carrying path for a recording medium is divided into a plurality of passages. <P>SOLUTION: In this inkjet recording apparatus, a recording paper P placed at a placing position 49 on the outer peripheral face of belts 23a-23c is carried in the X direction by a carrying force of the belts 23a-23c, and by the time when the tip part 47 of the recording paper P reaches a carrying force changing position 57 where the carrying force is changed to the carrying force of belts 25a-25d, a timing for delivering the ink droplets is made to be a first delivering timing based on a scale detecting signal by a first linear encoder 29. At the time when the tip part 47 reaches the carrying force changing position 57, the delivering timing is switched to a second delivering timing when a phase to the scale detecting signal at the first linear encoder 29 is corrected to the scale detecting signal by the second linear encoder 31. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus.

In recent years, in an ink jet recording apparatus that records on a recording medium by ejecting ink droplets from nozzles, a line type in which a large number of nozzles are arranged over a length longer than the width of the recording medium due to a demand for higher recording speed. An ink jet recording apparatus (hereinafter referred to as a line type ink jet recording apparatus) provided with a recording head (hereinafter referred to as a line head) has been put into practical use.

In this line type ink jet recording apparatus, conventionally, a line head cleaning unit (cap) is disposed in a non-image area (non-recording area) outside a recording area, which is an area where recording is performed on recording paper (recording medium). In addition, a configuration is known in which cleaning is performed by rotating the line head in the recording area to a position where the nozzle faces the cleaning unit in the non-image area (see, for example, Patent Document 1).

JP 2002-103638 A (page 4, FIGS. 5 and 6)

In the conventional example described in Patent Document 1, the recording head (line head) is rotated between the recording area and the non-recording area. In other words, in the conventional example described in Patent Document 1, since the recording head must be rotated without damaging the recording head, which is an assembly of precision parts, without impact, the recording head is rotated. There is a problem that the mechanism and control for making it complicated, and a problem that it is difficult to shorten the time required to rotate without giving an impact. In addition, since a cleaning unit (cap) must be provided in the non-recording area, there is a problem that it is difficult to reduce the size of the ink jet recording apparatus.

In order to solve these problems, the applicant of the present invention is an inkjet recording apparatus I shown in FIG.
JP configuration is proposed (PCT / JP2005 / 000778). This ink jet recording apparatus IJP has a plurality of conveying belts V1 and V2 respectively connected to a first driven roller FS1.
And a sheet conveyance section CV having a configuration in which the drive roller DS and the drive roller DS and the second driven roller FS2 are alternately arranged, and the head unit HU is disposed at a position facing the conveyance belts. The cap CA covering the nozzles of the head units HU is arranged at a position facing the head units HU across the conveyance path of the recording paper P. When the nozzle is covered with the cap CA, the cap CA rises in the direction of the arrow in the figure and comes into contact with each head unit HU. In addition, the symbol Mo of this figure shows the motor which generate | occur | produces the motive power for driving the drive roller DS.

As shown in FIG. 18A, which is a plan view, the paper transport unit CV of the ink jet recording apparatus IJP includes a first driven roller FS1, from the upstream in the X direction, which is the transport direction of the recording paper P, to the downstream. A driving roller DS and a second driven roller FS2 are arranged in this order, and a conveying belt V1 is laid between the first driven roller FS1 and the driving roller DS;
The driving roller DS unit is connected to the first conveying unit CV1, and the conveying belt V2 is configured by a second conveying unit CV2 provided between the driving roller DS and the second driven roller FS2. In this paper transport section CV, the transport belt V1 and the transport belt V2 are driven by a common drive roller DS, and rotate in the counterclockwise direction as viewed in FIG. Transport in X direction.

Here, in general, in an ink jet recording apparatus, recording is performed by measuring the ejection timing of ink droplets based on the transport position of the recording paper. In the above-described paper transport unit CV, for example, a linear scale is provided on one side edge of the transport belt V1, the scale of the linear scale is detected by an encoder, and the transport position of the recording paper P is grasped. It is conceivable to measure the discharge timing based on this. That is, one rotation position of the conveyance belt V1 is detected by the linear scale and the encoder, and the discharge timing and the second conveyance unit in the first conveyance unit CV1 are determined based on the conveyance position of the recording paper P grasped from the rotation position. CV
Both the discharge timings in 2 are measured.

However, in the paper transport unit CV, as shown in FIG. 18B, the first transport path P
Since the conveyance belt V1 is on the tight side at L1 and the conveyance belt V2 is on the loose side on the second conveyance path PL2, the conveyance speed of the first conveyance unit CV1 and the conveyance speed of the second conveyance unit CV2 may be different. When the conveyance speeds of the first conveyance unit CV1 and the second conveyance unit CV2 are different, the discharge timings of both the first conveyance unit CV1 and the second conveyance unit CV2 are determined based on the rotation position of the conveyance belt V1 detected by the encoder. In the above-described example to be measured, there is an unsolved problem that the discharge timing in the second transport unit CV2 is not an appropriate timing.

The present invention has been made paying attention to this unsolved problem, and can perform recording by ejecting ink droplets at an appropriate timing even when the conveyance path of the recording medium is divided into a plurality of paths. It is an object of the present invention to provide an ink jet recording apparatus that can be used.

According to a first aspect of the present invention, an endless first conveying belt that conveys a recording medium is wound around a driving roller and is laid over the upstream side in the conveying direction of the recording medium with respect to the driving roller. An endless second transport belt for transporting the medium is wound around the drive roller so that the first transport belt and the first transport belt are alternately arranged in the axial direction of the drive roller, and the transport roller is more transported than the drive roller. A recording medium conveying means having a configuration erected toward the downstream side in the direction, and a nozzle for discharging ink droplets, and the first and second of the recording medium conveyed by the recording medium conveying means. The ink droplets are ejected onto the recording surface opposite to the surface placed on the conveyor belt at an ejection timing at which ejection of the ink droplets is permitted, and one line is formed in a direction perpendicular to the transport direction. Align to A recording head that can be formed without moving a number of dots, a first timing generation unit that generates the first ejection timing based on the rotation amount of the first transport belt, and the second A second timing generation unit that generates the second ejection timing based on the rotation amount of the conveyance belt; and the recording that is sent from the first conveyance belt to the second conveyance belt across the drive roller. Recording medium detecting means for detecting that the medium has reached a conveyance force change position, which is a position where the conveyance force of the recording medium on the second conveyance belt is equal to or higher than the conveyance force on the first conveyance belt; The discharge timing is changed from the first discharge timing to the second discharge timing based on the fact that the recording medium detection means detects the arrival of the recording medium at the conveyance force change position. When the ejection timing switching means for switching to the recording medium and the recording medium detection means detect the arrival of the recording medium at the transport force change position, the phase of the second ejection timing with respect to the first ejection timing is corrected. And a phase correction means.

Here, the conveyance force is the maximum static friction force that acts on the recording medium along the conveyance direction of the recording medium between the conveyance belt and the recording medium. Further, correcting the phase means that the first discharge timing immediately before the discharge timing is switched from the first discharge timing to the second discharge timing, and the discharge timing is switched from the first discharge timing to the second discharge timing. That is, the second ejection timing is corrected so that the interval from the second ejection timing immediately after being performed becomes an interval corresponding to the recording resolution.

In the first invention, the recording head performs recording on the recording medium by ejecting ink droplets at the first ejection timing until the recording medium detecting means detects the arrival of the recording medium at the conveyance force change position. . The recording head ejects ink droplets at the second ejection timing in which the phase with respect to the first ejection timing is corrected after the recording medium detection means detects the arrival of the recording medium at the conveyance force change position. Recording on this recording medium is continued. Therefore, even if the recording medium conveying section in the recording medium conveying means is divided by the first conveying belt and the second conveying belt, it is possible to perform recording by ejecting ink droplets at an appropriate ejection timing. It becomes.

In a second aspect based on the first aspect, the transport force per unit area of the recording medium on the second transport belt is the per unit area of the recording medium on the first transport belt. Friction force increasing means for increasing the friction force acting between the second conveyance belt and the recording medium so as to be larger than the conveyance force is provided.

In the second aspect of the invention, there is provided friction force increasing means for increasing the friction force acting between the second transport belt and the recording medium, and the transport force per unit area of the recording medium on the second transport belt is The conveyance force per unit area of the recording medium on the first conveyance belt is larger. As a result, the conveyance force of the recording medium on the second conveyance belt can be easily made larger than the conveyance force of the recording medium on the first conveyance belt.

In a third aspect based on the second aspect, the frictional force increasing means includes belt charging means for charging the second conveying belt, and the recording medium is adsorbed to the charged second conveying belt. And the frictional force is increased.

In the third aspect of the invention, the recording medium can be adsorbed to the charged second transport belt,
The frictional force can be increased.

In a fourth aspect based on any one of the first to third aspects, the second transport belt is
The conveyance speed for conveying the recording medium is set to be higher than the conveyance speed of the first conveyance belt.

In the fourth aspect of the invention, since the conveying speed of the second conveying belt is set to be higher than the conveying speed of the first conveying belt, the recording medium has the conveying force of the second conveying belt equal to that of the first conveying belt. When the conveyance force of one conveyance belt is exceeded, the conveyance speed is controlled by the second conveyance belt. When the conveyance speed is governed by the second conveyance belt, the recording medium is pulled by the second conveyance belt, and the recording medium is separated from the first conveyance belt having a conveyance force smaller than the conveyance force of the second conveyance belt. Slip occurs between them.
That is, it is possible to suppress the influence of the rotation state of the first conveying belt to a low level, and to convey the recording medium in a stable state with the second conveying belt with low occurrence of wrinkles. Accordingly, it is possible to perform recording by ejecting ink droplets at an appropriate ejection timing, and it is possible to further improve the recording quality.

In a fifth aspect based on the fourth aspect, the conveying speed is such that the outer diameter of the portion of the drive roller around which the second conveying belt is wound is the portion where the first conveying belt is wound. The outer diameter of the second conveyor belt is set to be higher than that of the first conveyor belt.

In the fifth aspect of the invention, the outer diameter of the portion around which the second conveying belt of the drive roller is wound is the first diameter.
Since the outer diameter of the portion around which the conveyor belt is wound is set larger, the conveyance speed of the second conveyor belt can be made faster than the conveyance speed of the first conveyor belt.

According to a sixth invention, in any one of the first to third inventions, the invention further comprises phase difference detection means for detecting a phase difference between the first discharge timing and the second discharge timing, and the phase correction means. Is based on the phase difference detected by the phase difference detecting means, and the recording medium detecting means detects the arrival of the recording medium at the transport force change position when the recording medium is detected at the second ejection timing. The phase with respect to the first ejection timing is corrected.

In this sixth invention, the phase correction means is based on the phase difference detected by the phase difference detection means,
The phase of the second ejection timing with respect to the first ejection timing is corrected. Thereby, the phase difference between the first ejection timing and the second ejection timing can be detected, and the phase can be corrected by the detected phase difference.

1st Embodiment of this invention is described based on drawing.
The ink jet recording apparatus 1 according to the first embodiment of the present invention is a plan view of FIG.
1B, which is a front view, a gate roller 2, a paper feed motor 3 that generates power for driving the gate roller 2, a paper transport unit 4, a paper detection sensor 5, A first recording head 6 and a second recording head 7 are provided. In the drawing, the X direction indicates the conveyance direction of the recording paper P, and the Y direction indicates a direction orthogonal to the X direction.
The ink jet recording apparatus 1 is a so-called line type ink jet recording apparatus that completes recording without moving the first recording head 6 and the second recording head 7 during recording.

  Here, the detail of each said structure is demonstrated.

As shown in FIG. 1A, the gate roller 2 is disposed on the upstream side in the X direction of the paper transport unit 4. As shown in FIG. 1B, the gate roller 2 is in contact with each of the recording surface 8 and the placement surface 9 of the recording paper P to sandwich the recording paper P, and is configured to be rotatable. It has a roller. When the gate roller 2 is driven by the power from the paper feed motor 3 and is supplied so that the recording paper P is abutted between a pair of rollers of the gate roller 2 from a paper feed unit (not shown), the recording paper After performing skew correction for correcting the tilt of P with respect to the X direction and the positional deviation in the Y direction, the recording paper P is supplied to the paper transport unit 4.

As shown in FIG. 2A, which is a plan view, the paper transport unit 4 includes a transport motor 13 that generates power for driving the paper transport unit 4, and a drive roller 1 to which power is transmitted from the transport motor 13.
5, a first driven roller 17 disposed on the upstream side in the X direction of the drive roller 15, and the drive roller 1
5, a second driven roller 19 disposed downstream in the X direction, a first belt group 23 stretched between the driving roller 15 and the first driven roller 17, and the driving roller 15 and the second driven roller 19. A second belt group 25 stretched between them, a first linear encoder 29 that detects the rotational position of the first belt group 23, and a second linear that detects the rotational position of the second belt group 25. And an encoder 31.

The first belt group 23 includes four belts 23 a, 23 b, 23 c, and 23 d provided between the driving roller 15 and the first driven roller 17. Each belt 23a-23d
The thickness, width, and circumference are set equally between these belts 23a-23d. Also,
As shown in FIG. 2A, the positions of the belts 23a to 23d in the Y direction are regulated by flange portions 27 provided on the driving roller 15 and the first driven roller 17, respectively. A gap is maintained.

The second belt group 25 includes five belts 25 a, 25 b, 25 c, 25 d, and 25 e installed between the driving roller 15 and the second driven roller 19. Each belt 25a
˜25e has the same thickness, width and circumferential length between these belts 25a to 25e. Further, these belts 25a to 25e are respectively regulated in the Y direction by the flange portions 27 provided on the driving roller 15 and the second driven roller 19, respectively, so that a gap of H1 is maintained.

Furthermore, the belts 23 a to 23 d in the first belt group 23 and the belts 25 a to 25 e in the second belt group 25 are laid on the drive roller 15 so as to be alternately arranged in the Y direction. That is, the belts 23a to 23d of the first belt group 23 and the belts 25a to 25e of the second belt group 25 are laid so as to be alternated as shown in FIG. The thickness of each flange portion 27 in the radial direction is set to a thickness that does not protrude outward from the outer peripheral surfaces of the belts 23a to 23d and 25a to 25e so as not to hinder the conveyance of the recording paper P. Moreover, the thickness of each belt 23a-23d, 25a-25e is
All are set to equivalent dimensions.

Here, although not shown in the figure, linear scales each having a plurality of scales arranged at predetermined intervals along the X direction are provided on the outer peripheral surfaces of the belts 23d and 25e. The plurality of scales formed on each linear scale are formed at intervals corresponding to the recording resolution in the X direction of the inkjet recording apparatus 1.

The first linear encoder 29 is disposed so as to sandwich the belt 23d and the linear scale provided on the outer peripheral surface of the belt 23d from one side edge side of the belt 23d, and the second linear encoder 31 is The belt 25e and the linear scale provided on the outer peripheral surface of the belt 25e are arranged so as to be sandwiched from one side edge side of the belt 25e.

Each of the first and second linear encoders 29 and 31 is composed of, for example, a reflective optical sensor having a light emitting element and a light receiving element, and the amount of light received by the light receiving element is reduced by the scale formed on the linear scale. When it changes, the output voltage is changed in a pulse shape. That is, each of the first and second linear encoders 29 and 31 changes the output voltage from the Lo level to the Hi level each time a scale is detected.

In the inkjet recording apparatus 1, the first linear encoder 29 is the belt 23d.
The rotational position of the first belt group 23 is grasped based on the result of detecting the linear scale, and the second belt group 25 is determined based on the result of the second linear encoder 31 detecting the linear scale of the belt 25e. The rotation position of is understood.

Further, as shown in FIG. 2B, the paper transport unit 4 includes a belt 23a of the first belt group 23.
A first belt charging unit 35 that charges the belts 23a to 23c of the second belt group 25, and a second belt charging unit 37 that charges the belts 25a to 25d of the belts 25a to 25e of the second belt group 25. It has.

As shown in FIG. 2 (b), the first belt charging unit 35 includes the first driven roller 1 as viewed in this figure.
7 includes a first charging roller 39 that contacts the outer peripheral surfaces of the belts 23a to 23c, and a first charging power source 41 that is connected to the first charging roller 39 and generates an AC voltage. The first belt charging unit 35 is connected to the belt 23a from the first charging power source 41 via the first charging roller 39.
These belts 23a-23c are alternately charged on the positive electrode side and the negative electrode side by applying an AC voltage to .about.23c.

Similarly, the second belt charging unit 37 includes a second charging roller 43 that contacts the outer peripheral surface of the belts 25 a to 25 d below the driving roller 15 as viewed in FIG. A second charging power supply 45 that is connected and generates an AC voltage, and the AC voltage is applied from the second charging power supply 45 to the belts 25a to 25d via the second charging roller 43, thereby the belts 25a to 25d.
Are alternately charged on the positive electrode side and the negative electrode side.

The charged belts 23a to 23c and 25a to 25d are subjected to an adsorbing force between the recording paper P and the outer peripheral surfaces of the belts 23a to 23c and 25a to 25d. Note that the AC voltage generated by the second charging power supply 45 is set to an amplitude larger than the amplitude of the AC voltage generated by the first charging power supply 41. As a result, the belts 25a to 25d
The charge amount per unit area of each outer peripheral surface is larger than the charge amount per unit area of the outer peripheral surface in each of the belts 23a to 23c. That is, the suction force acting per unit area of the recording paper P on the belts 25a to 25d is set to be larger than the suction force acting per unit area of the recording paper P on the belts 23a to 23c.

In the paper transport unit 4 having the above-described configuration, the driving roller 15 is driven to rotate counterclockwise by the power of the transport motor 13 as viewed in FIG. 2B, which is a front view, and is shown in FIG. As described above, the recording paper P has a leading end 47 of the recording paper P and the belts 23 a to 23 b of the first belt group 23.
A separation position that is a position at which the rear end portion 51 of the recording paper P is separated from the outer peripheral surfaces of the belts 25a to 25d of the second belt group 25 from the mounting position 49 that is a position to be mounted on the outer peripheral surface of 23c. 5
Up to 3 in the X direction. At this time, the recording paper P is conveyed so as not to cover the outer peripheral surface of the belt 23d and the outer peripheral surface of the belt 25e. These belt 23d and belt 25
e is used exclusively for linear scale detection.

In the paper transport unit 4, the transport path of the recording paper P is between the first driven roller 17 and the driving roller 15 by the belts 23 a to 23 c of the first belt group 23 as shown in FIG. The first transport path PL1 formed, and the second transport path PL2 formed by the belts 25a to 25d of the second belt group 25 between the driving roller 15 and the second driven roller 19.
And divided. The first transport path PL1 and the second transport path PL2 are connected to the connection position 55.
Are connected in the X direction.

Here, a process in which the recording paper P is transported along the first transport path PL1 and the second transport path PL2 will be described with reference to FIG.

In the paper transport unit 4, the recording paper P is adsorbed and placed on the outer peripheral surfaces of the belts 23a to 23c of the first belt group 23 at the placement position 49, as shown in FIG. The And this recording paper P is between the outer peripheral surface of the belts 23a-23c and the mounting surface 9 of the recording paper P,
Due to the action of the conveying force which is the maximum static frictional force acting along the X direction, the belts 23a to 23a.
It is held on the outer peripheral surface of c and is conveyed along the first conveyance path PL1.

Next, as shown in FIG. 3B, the recording paper P crosses the driving roller 15 from the outer peripheral surface of the belts 23 a to 23 c of the first belt group 23 at the connection position 55, and passes through the second belt group 2.
5 is gradually sent to the outer peripheral surfaces of the belts 25a to 25d. At this time, the recording paper P is conveyed by being controlled by the conveying speed of the first belt group 23 until the conveying force of the belts 25a to 25d becomes equal to or higher than the conveying force of the belts 23a to 23c. Therefore, even if there is a difference in the conveyance speed between the first belt group 23 and the second belt group 25, the placement surface 9 of the recording paper P and the belt 2
Slip occurs between the outer peripheral surfaces of 5a to 25d.

Next, as shown in FIG. 3C, when the leading end portion 47 reaches a conveyance force change position 57 that is a position where the conveyance force in the belts 25a to 25d and the conveyance force in the belts 23a to 23c become equal. The recording paper P is controlled by the second belt group 25 in terms of conveyance force. At this time, the first
Even if there is a difference in the transport speed between the belt group 23 and the second belt group 25, the recording paper P is held on the outer peripheral surfaces of the belts 25a to 25d and the outer peripheral surfaces and the placement surfaces of the belts 23a to 23c. 9
Slip occurs between the two.

Next, as shown in FIG. 3 (d), the recording sheet P has its leading end 47 positioned at the separation position 53 as X.
When crossing the direction, the belts 25a to 25d are sequentially separated from the outer peripheral surfaces. And the rear end 5
2 is separated from the outer peripheral surfaces of the belts 25a to 25d at the separation position 53 as shown in FIG. 2B, the conveyance of one recording sheet P is completed.

The paper detection sensor 5 is constituted by, for example, a reflection type photo interrupter, and as shown in FIGS. 4A and 4B, at the conveyance force change position 57 between the belt 25b and the belt 25c,
The second belt group 25 is disposed above the outer peripheral surface of the second belt group 25 as viewed in FIG. This sheet detection sensor 5 changes the output voltage when the leading end portion 47 of the recording sheet P conveyed through the second conveyance path PL2 through the first conveyance path PL1 reaches the conveyance force change position 57. That is, the paper detection sensor 5 detects that the leading end portion 47 of the recording paper P has reached the conveyance force change position 57 and outputs the detection result as a paper detection signal.

Here, the conveyance force in the belts 23a to 23c, the conveyance force in the belts 25a to 25d, and the conveyance force change position 57 will be described. Here, the recording paper P is the belts 23a-2.
3c straddling the driving roller 15 and gradually being fed to the belts 25a to 25d, and the leading end 4
Assume that 7 has reached the conveyance force change position 57 as shown in FIG. Also,
In FIG. 4A, the recording paper P is shown by a broken line in order to easily show the configuration.

At this time, the conveying force F ₁ in the belt 23a~23c is calculated by the following equation (1).
F ₁ = μ × f ₁ × L ₁ × W × 3 (1)
In the above equation (1), μ is a friction coefficient between the belts 23a to 23c and 25a to 25d and the recording paper P, and f ₁ is an adsorption force acting per unit area of the recording paper P on the belts 23a to 23c. It is. L ₁ is the distance from the mounting position 49 to the connection position 55 as shown in FIG. W is the width in the Y direction of each belt 23a-23c.

Further, the conveying force F ₂ in the belt 25a~25d is calculated by the following equation (2).
F ₂ = μ × f ₂ × L ₂ × W × 3 (2)
In the above formula (2), f ₂ is an attractive force acting per unit area of the recording paper P in the belts 25a to 25d. In addition, L ₂ is a connecting position 55 as shown in FIG.
To the conveyance force change position 57. W is the width in the Y direction of each of the belts 25a to 25d. In the present embodiment, each of the belt 25a and the belt 25d includes
As shown in FIG. 4A, the recording paper P is placed in the Y direction by (W / 2).

Since the conveyance force change position 57 is a position where F ₁ = F ₂ , the distance L ₂ is expressed by the following expression (3) from the above expressions (1) and (2).
L ₂ = (f ₁ / f ₂ ) × L ₁ (3)
Accordingly, the conveyance force change position 57 is specified by the distance L ₂ calculated by the above equation (3).

The distance L ₂ is calculated in such a way that the length of the recording paper P in the X direction is equal to the path length of the first transport path PL1 and the path length of the second transport path PL2, as shown in FIG. Applicable when longer than sum. When the length of the recording paper P in the X direction is shorter than the sum of the path length of the first transport path PL1 and the path length of the second transport path PL2, the distance L ₁ is as shown in FIG. The distance from the rear end portion 51 of the recording paper P to the connecting position 55 may be replaced.

The first recording head 6 includes four head units 6 as shown in FIG.
a, 6b, 6c and 6d. Further, as shown in FIG. 6A, the second recording head 7 includes three head units 7a, 7b, and 7c.

As shown in FIG. 6B, which is a front view, the first recording head 6 is formed with nozzles for ejecting ink droplets on the upper side of the first belt group 23 across the first transport path PL1. A gap is maintained between the nozzle surface 61 and the recording surface 8 of the recording paper P. In addition, the second recording head 7 is disposed above the second belt group 25 with the second transport path PL2 interposed therebetween and with a gap between the nozzle surface 61 and the recording surface 8.

As shown in FIG. 6A, the head units 6a to 6d in the first recording head 6 are
The belts 23a to 23d in the first belt group 23 are arranged alternately in the Y direction.

Among these head units 6a to 6d, the head units 6b, 6c and 6d are arranged such that the head unit 6b is located at a position facing the belt 23a and 23b, and the head unit 6c is located at the position facing the belt 23b and 23c. Unit 6d is belts 23c and 2
It is arrange | positioned in the position which opposes between 3d. As shown in FIG. 6A, the head unit 6a is disposed at a position adjacent to the head unit 6b with the belt 23a interposed therebetween.

The head units 7a to 7c in the second recording head 7 are arranged so as to be alternately arranged in the Y direction with the belts 25a, 25b, 25c, and 25d in the second belt group 25, respectively.

As shown in FIG. 6A, these head units 7a to 7c are the same as the head unit 7a.
Is disposed between the belts 25a and 25b, the head unit 7b is disposed between the belts 25b and 25c, and the head unit 7c is disposed between the belts 25c and 25d.

Here, the arrangement of the nozzles formed in each of the head units 6a to 6d and 7a to 7c will be described. The head units 6a to 6d and 7a to 7c have the same configuration. Therefore, here, the nozzle arrangement will be described using the head unit 6a as an example.

As shown in FIG. 7A, which is a bottom view, the head unit 6a includes a nozzle 63y that ejects yellow ink droplets onto a nozzle surface 61 and a nozzle 63m that ejects magenta ink droplets.
The nozzles 63c for discharging cyan ink droplets and the nozzles 63k for discharging black ink droplets are arranged in an array from the upstream side in the X direction to the downstream side with a gap therebetween.

Further, these nozzles 63y, 63m, 63c, and 63k are arrayed over a distance H2 at a predetermined interval along the Y direction, and constitute a nozzle row for each color. The distance H2 and the gap H1 between the belts 23a to 23d and 25a to 25e described above have a relationship of H2 <H1. The head units 6a to 6d and 7a to 7c are arranged so that the nozzles 63y, 63m, 63c, and 63k do not overlap the belts 23a to 23d and 25a to 25e in plan view.

Further, the head units 7a to 7c of the second recording head 7 are translated in the X direction upstream side,
When all the head units 6a to 6d and 7a to 7c are virtually aligned in the Y direction, one nozzle row of each color is formed as shown in FIG. 7B. That is, the first recording head 6
In addition, the second recording head 7 is configured to be able to form on the recording paper P a dot row that is aligned with one row of each color in the Y direction.

In FIG. 7, the nozzles 63y, 63m, 63 are shown for easy understanding of the configuration.
The size of c and 63k is exaggerated and the number is reduced. In addition, as the head units 6a to 6d and 7a to 7c, head units that apply ink pressure by a piezoelectric element, a heating element, or the like to eject ink droplets can be employed.

The first recording head 6 and the second recording head 7 having the above-described configuration are supplied from a host computer such as a personal computer or a digital still camera onto the recording surface 8 of the recording paper P conveyed in the X direction by the paper conveying unit 4. Based on the recording information, the head units 6a to 6d
And 7a to 7c, ink is selectively ejected from all the nozzles 63y, 63m, 63c and 63k to perform recording.

In this recording, the first recording head 6 is placed on the recording paper P moving in the X direction on the first transport path PL1, and the plurality of nozzles 63y, 63m, 63c and 63k in the head units 6a to 6d.
Ink droplets are selectively ejected from the first recording. Then, the second recording head 7 selectively ejects ink droplets from the plurality of nozzles 63y, 63m, 63c and 63k in the head units 7a to 7c onto the recording paper P moving in the X direction along the second transport path PL2. The second recording is performed and the recording on one recording paper P is completed.

Here, the first recording head 6 and the second recording head 7 are allowed to eject ink droplets at the ejection timing corresponding to the recording resolution in the X direction. The discharge timing includes the first discharge timing generated based on the result of the first linear encoder 29 detecting the scale and the first discharge timing generated based on the result of the second linear encoder 31 detecting the scale. 2
Discharge timing. Details of the generation of the first discharge timing and the second discharge timing will be described later.

As the discharge timing, the first discharge timing is adopted during the period in which the conveyance force of the recording paper P described above is governed by the first belt group 23. Then, when the conveyance force of the recording paper P is dominated by the second belt group 25, the second ejection timing is switched. That is, when the paper detection sensor 5 detects the leading edge 47 of the recording paper P, the ejection timing is switched from the first ejection timing to the second ejection timing.

Further, as shown in FIG. 8, the inkjet recording apparatus 1 includes a control circuit 71 that controls the operation of each of the above-described configurations. The control circuit 71 includes a control unit 72, a paper feed motor driver 73, a transport motor driver 74, a charging power source driver 75, an ejection timing generation circuit 76, a recording head driver 77, and an interface unit 78. Yes.

The control unit 72 includes, for example, a microcomputer, and includes a CPU (Central Processing Unit) 721 that executes various processes such as a recording process, and a memory unit 722.

The memory unit 722 includes a RAM (Random Access Memory) and a ROM (Read-Only Memory).
And so on.

The RAM stores recording information from a host computer 79 such as a personal computer or a digital still camera, temporarily develops application programs such as recording processing executed by the CPU 721, and temporarily stores various data. Or R
The OM is composed of a nonvolatile semiconductor memory, and stores a control program executed by the CPU 721 and the like.

The paper feed motor driver 73 controls the paper feed motor 3. The carry motor driver 74 controls the carry motor 13. The charging power source driver 75 individually controls each of the first charging power source 41 and the second charging power source 45.

The recording head driver 77 individually controls the head units 6 a to 6 d and 7 a to 7 c in the first recording head 6 and the second recording head 7. The interface unit 78 receives recording information such as image data output from the host computer 79 and then controls the control unit 72.
Or after receiving various kinds of information output from the control unit 72, the information is output to the host computer 79.

As shown in FIG. 9, the discharge timing generation circuit 76 includes a phase difference detection circuit 761, a phase shift circuit 762, and a switch circuit 763.
The phase difference detection circuit 761 includes a scale detection signal E1 from the first linear encoder 29,
A phase difference from the scale detection signal E2 in the second linear encoder 31 is detected, and the result is output to the phase shift circuit 762.

The phase shift circuit 762 generates a phase correction signal SP in which the phase difference of the scale detection signal E2 with respect to the scale detection signal E1 is corrected based on the phase difference detected by the phase difference detection circuit 761, and the phase correction signal SP is generated. Output to the switch circuit 763.

As shown in FIG. 9, the switch circuit 763 includes the first linear encoder 29 and the control unit 7.
2 and the connection between the phase shift circuit 762 and the control unit 72 are switched. In the initial state (reset state), the switch circuit 763 connects the first linear encoder 29 and the control unit 72 as shown in FIG. 9, and in this state, the scale detection from the first linear encoder 29 is performed. The signal E1 is output to the control unit 72 as the ejection timing signal TP.

When the switching signal SW is input from the control unit 72, the switch circuit 763 is switched in connection, and connects the phase shift circuit 762 and the control unit 72 as indicated by a broken line in FIG. In the switch circuit 763, a state where the connection is switched from the initial state is referred to as a switching state. In the switching state, the switch circuit 763 outputs the phase correction signal SP to the control unit 72 as the ejection timing signal TP.

The switching signal SW output from the control unit 72 is generated when the above-described sheet detection sensor 5 detects the leading end 47 of the recording sheet P, that is, the sheet detection signal DP of the sheet detection sensor 5 changes from Lo level to Hi level. When changed, the Lo level is switched to the Hi level. This switching signal SW is input to the switch circuit 763 and also to the phase difference detection circuit 761.

The switch circuit 763 changes from the initial state to the switching state based on the change of the switching signal SW from the Lo level to the Hi level. In the phase difference detection circuit 761, the switching signal SW is L
The phase difference detected immediately before the change from the o level to the Hi level is latched (held) based on the change of the switching signal SW from the Lo level to the Hi level, and the latched phase difference is output to the phase shift circuit 762. .

Here, the flow of the various signals described above will be described based on the timing chart shown in FIG. In FIG. 10, in order to show each signal in an easy-to-understand manner, the ejection timing signal TP is divided at the rising edge of the paper detection signal DP, and the ejection timing signal TP during the period when the paper detection signal DP is at the Lo level In the upper part, the discharge timing signal TP in the period in which the paper detection signal DP is at the Hi level is shown in the lower part of the figure.

And scale detection signal E1 and scale detection signal E2 has a phase difference obtained as G ₁ between the first rising edge each other have a phase difference obtained as G ₂ between the second rising edge between, 3
Th has a phase difference obtained as G ₃ between the rising edge each other, and had a phase difference comprising G _n between n-th rising edge together.

At this time, the switch circuit 763 is in an initial state because the paper detection signal DP is at the Lo level. Accordingly, as the ejection timing signal TP at this time, the scale detection signal E1 is output as shown in FIG.

Phase difference detecting circuit 761, the phase difference G _1, the phase difference G _2, the phase difference G _3, each time it detects a ... phase difference G _n, and outputs the phase differences G ₁ ~G _n to the phase shift circuit 762 . Phase shift circuit 76
2, when the phase difference G ₁ ~G _n is input, and outputs a phase correction signal SP which is corrected based on the scale detection signal E2 to each phase difference G ₁ ~G _n. That is, the first rising edge of the phase correction signal SP is delayed by the phase difference G ₁ from the second rising edge of the scale detection signal E2, and the first falling edge of the phase correction signal SP is the scale detection. Signal E2
It occurs with a phase difference G ₁ delayed from the second falling edge. Similarly, each of the (n-1) th rising edge and falling edge of the phase correction signal SP has a phase difference G from each of the nth rising edge and falling edge of the scale detection signal E2.
Occurs after _n-1 .

Here, when the phase difference detection circuit 761 detects the phase difference G _n , the paper detection signal DP is H
Assume that the level has changed to i level. Based on the change of the paper detection signal DP to the Hi level,
The control unit 72 changes the switching signal SW from the Lo level to the Hi level, and this switching signal SW
Is output to the switch circuit 763 and the phase difference detection circuit 761. When the switching signal SW changes to the Hi level, the switch circuit 763 changes from the initial state to the switching state, and the phase difference detection circuit 7
61 is a phase difference G _n detected immediately before the switching signal SW changes from Lo level to Hi level.
Latch.

When the phase difference detection circuit 761 latches the phase difference G _n , the phase shift circuit 762 outputs a phase correction signal SP obtained by correcting the scale detection signal E2 based on the phase difference G _n . That means
From the time point when the paper detection signal DP changes to Hi level, the rising edge and falling edge of the phase correction signal SP are delayed by the phase difference G _n from the rising edge and falling edge of the scale detection signal E2, respectively. appear.

Since the switch circuit 763 is changed to the switching state when the paper detection signal DP changes to the Hi level, the ejection timing signal TP thereafter is output with the phase correction signal SP as shown in FIG. The In the ejection timing signal TP, rising edges TPa and TPb from the Lo level to the Hi level are ejection timings that permit ejection of ink droplets. The discharge timing TPa based on the scale detection signal E1 is the first discharge timing, and the discharge timing TPb based on the scale detection signal E2 is the second discharge timing.

A flow of recording processing and recording operation in the inkjet recording apparatus 1 having the above-described configuration will be described.
In the inkjet recording apparatus 1, when the control unit 72 receives recording information from the host computer 79 via the interface unit 78, the CPU 721 starts the recording process illustrated in FIG. 11.

In this recording process, first, in step S1, a conveyance unit drive command is output to the conveyance motor driver 74, and the first belt group 23 and the second belt group 25 are counterclockwise as viewed in FIG. The conveyance motor 13 is driven to rotate, and the process proceeds to step S2.

In step S2, a belt charging command is output to the charging power source driver 75, an AC voltage is generated from each of the first charging power source 41 and the second charging power source 45, and the process proceeds to step S3.
In step S3, the count value Ct of the discharge timing signal TP is reset, and the process proceeds to step S4.

In step S4, a reset signal for the switch circuit 763 is output, the switch circuit 763 is initialized, and the process proceeds to step S5.
In step S5, a paper feed command is output to a paper feed unit (not shown).
The sheet of recording paper P is supplied to the gate roller 2, and the process proceeds to step S6. At this time, the recording paper P is abutted between the pair of rollers of the gate roller 2 and skew-corrected.

In step S6, a paper supply command is output to the paper feed motor driver 73, and the paper feed motor 3 is rotated so that the gate roller 2 rotates in the direction of feeding the recording paper P in the X direction as seen in FIG. Then, the recording paper P is supplied to the outer peripheral surfaces of the belts 23a to 23c of the first belt group 23, and the process proceeds to step S7.

In step S7, the ejection timing signal T input from the switch circuit 763.
The count of P is started and the process proceeds to step S8. Here, counting the ejection timing signal TP means counting the number of times the ejection timing signal TP is switched from the Lo level to the Hi level.

In step S8, the count value Ct is determined whether reaches a predetermined value Ct _1, it is determined reaches the a (YES), there moves to step S9, if it is determined that not reached (NO) The process waits until the count value Ct reaches the predetermined value Ct ₁ . Here, the predetermined value Ct ₁ is the first recording start position where the recording paper P is the position of the nozzle 63y on the most upstream side of the first recording head 6 from the placement position 49 in plan view, as shown in FIG. It is set to a value counted while being conveyed up to 81.

In step S9, the first recording start command is output to the recording head driver 77 to start the drive control of the head units 6a to 6d, and the first recording head 6 starts the first recording based on the recording information. Then, the process proceeds to step S10. In the first recording here, as described above, the ejection of ink droplets is permitted at the ejection timing TPa based on the scale detection signal E1 from the first linear encoder 29.

In step S10, the count value Ct is determined whether reaches a predetermined value Ct _2, it is determined reaches the with (YES), there moves to step S11, if it is determined not to reach (NO) The process waits until the count value Ct reaches the predetermined value Ct ₂ . Here, the predetermined value Ct ₂ is the second recording start position where the recording paper P is the position of the nozzle 63y on the most upstream side of the second recording head 7 from the mounting position 49 in plan view as shown in FIG. It is set to a value counted while being conveyed up to 83.

In step S11, a second recording start command is output to the recording head driver 77,
Control of driving of the head units 7a to 7c is started, and the second recording head 7 starts the second recording based on the recording information, and the process proceeds to step S12. Even in the second recording here,
Ink droplet ejection is permitted at ejection timing TPa based on the scale detection signal E1 from the first linear encoder 29.

In step S12, it is determined whether or not the sheet detection signal DP has changed from the Lo level to the Hi level. If it is determined that the sheet detection signal DP has changed (YES), the process proceeds to step S13, and it is determined that it has not changed (NO). Then, it waits until the paper detection signal DP changes from the Lo level to the Hi level.

In step S13, the switching signal SW is changed from the Lo level to the Hi level, the switch circuit 763 is changed from the initial state to the switching state, and the process proceeds to step S14. By switching from the initial state to the switching state in the switch circuit 763, the discharge timing is switched from the discharge timing TPa based on the scale detection signal E1 to the discharge timing TPb based on the scale detection signal E2. Thereafter, the recording by the first recording head 6 and the second recording head 7 is continued at the discharge timing TPb.

In step S14, a paper discharge command is output to a paper discharge unit (not shown), and the recording paper P on which recording has been completed is discharged to the outside of the inkjet recording apparatus 1, and the process proceeds to step S15.
In step S15, it is determined whether or not the recording of all of the recording information has been completed. If it is determined that the recording has been completed (YES), the process proceeds to step S16, and has not been completed (N
If it is determined as O), the process proceeds to step S3.

In step S16, a belt charging stop command is output to the charging power source driver 75, and the first
The charging power supply 41 and the second charging power supply 45 are stopped from generating the AC voltage, and the process proceeds to step S17.
In step S <b> 17, a conveyance unit stop command is output to the conveyance motor driver 74 to stop driving the conveyance motor 13, and then the process ends.

In the first embodiment, the paper transport unit 4 corresponds to the recording medium transport unit, and the first belt group 2
Belts 23a to 23c among the belts 23a to 23d constituting the belt 3 correspond to the first conveying belt, and belts 25a to 25d among the belts 25a to 25e constituting the second belt group 25 are respectively Corresponding to the second conveyor belt, the first linear encoder 29 corresponds to the first timing generation unit, the second linear encoder 31 corresponds to the second timing generation unit, and the sheet detection sensor 5 corresponds to the recording medium. Corresponding to the detection means, the second belt charging unit 37 corresponds to the belt charging means as the frictional force increasing means, the phase difference detection circuit 761 corresponds to the phase difference detection means, and the phase shift circuit 762 serves as the phase correction means. Correspondingly, the switch circuit 763 corresponds to the discharge timing switching means.

In the ink jet recording apparatus 1 of the first embodiment, the transport path of the recording paper P in the paper transport unit 4 is divided into a first transport path PL1 and a second transport path PL2. First transport path PL
1, the rotational position of the first belt group 23 is grasped based on the scale detection signal E1 from the first linear encoder 29, and the second linear encoder 3 is obtained in the second transport path PL2.
The rotational position of the second belt group 25 is grasped based on the scale detection signal E2 from 1. Therefore, the first belt group 23 on the tension side in the first transport path PL1,
Even if the conveyance speed is different between the second belt group 25 on the loose side in the second conveyance path PL2,
It is possible to accurately grasp the rotational position of each of the first belt group 23 and the second belt group 25.

In addition, the inkjet recording apparatus 1 includes the phase difference detection circuit 7 in the ejection timing generation circuit 76.
61 and a phase shift circuit 762, the phase difference detection circuit 761 detects the phase difference between the scale detection signals E1 and E2, and based on the detected phase difference, the phase shift circuit 762 detects the scale detection signal E2. The phase with respect to the scale detection signal E1 is corrected. As a result, even when the switch circuit 763 enters the switching state, the discharge timing signal TP is changed to the discharge timing T.
It is possible to output in a good state with no phase difference between Pa and the discharge timing TPb.

As described above, even if the transport path of the recording paper P is divided into a plurality of sections, it is possible to complete recording by ejecting ink droplets at an appropriate ejection timing.

In the inkjet recording apparatus 1, the AC voltage of the second charging power supply 45 is set to an amplitude larger than the amplitude of the AC voltage of the first charging power supply 41. For this reason, belts 25a to 2
The suction force acting per unit area of the recording paper P in 5d is larger than the suction force acting per unit area of the recording paper P in the belts 23a to 23c. Thereby, it is possible to accurately and reliably set the transport force change position 57 in the second transport path PL2.

Further, in the ink jet recording apparatus 1, since the paper detection sensor 5 is disposed at the conveyance force change position 57, it is possible to accurately detect the time point at which the conveyance force of the recording paper P changes. It is possible to accurately switch from TPa to the discharge timing TPb.

A second embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 13 which is a block diagram, the inkjet recording apparatus 100 according to the second embodiment omits the ejection timing generation circuit 76 according to the first embodiment, and the first embodiment.
The thickness of the belt group 23 and the thickness of the second belt group 25 are set to different dimensions, and the outer diameter of the portion of the drive roller 15 around which the first belt group 23 is wound and the second belt group 25 are The structure is the same as that of the ink jet recording apparatus 1 of the first embodiment except that the outer diameter of the wound portion is set to a different size. Accordingly, parts corresponding to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

In the ink jet recording apparatus 100, as shown in FIG. 13, both the scale detection signal E1 and the scale detection signal E2 are input to the control unit 72, and the control unit 72 generates an ejection timing signal TP and sends it to the recording head driver 77. It is configured to output. Control unit 72
Outputs the scale detection signal E1 as the ejection timing signal TP to the recording head driver 77 during the period when the paper detection signal DP is at the Lo level, and the phase of the scale detection signal E2 during the period when the paper detection signal DP is at the Hi level. Is output to the print head driver 77 as the ejection timing signal TP.

Here, the phase of the scale detection signal E2 is corrected because the paper detection signal DP is Hi.
The scale detection signal E2 is corrected so that the discharge timing signal TP immediately before the change to the level and the discharge timing signal TP immediately after the paper detection signal DP has changed to the Hi level have an interval corresponding to the recording resolution. Say. Details of the phase correction of the scale detection signal E2 will be described later.

The drive roller 15 in the ink jet recording apparatus 100 is a portion around which each of the belts 25a to 25e of the second belt group 25 is wound, as shown in FIG. The outer diameter of the first belt group 23 is set to be larger than the outer diameter of the portion around which the belts 23a to 23d of the first belt group 23 are wound. Note that the outer diameters of the portions around which the belts 25a to 25e of the second belt group 25 are wound are all set to the same dimensions. Similarly, the outer diameters of the portions around which the belts 23a to 23d of the first belt group 23 are wound are all set to the same dimensions.

Comparing the lengths of the outer circumferences of the two outer diameter portions having different dimensions, the outer circumference length of the portion having the larger outer diameter is longer than the outer circumference length of the portion having the smaller outer diameter. In other words, when the driving roller 15 is rotated once, the transport distance in the second belt group 25 is greater than the transport distance in the first belt group 23 and the transport distance in the second belt group 25. become longer. Accordingly, the conveyance speed of the second belt group 25 is set to a speed higher than the conveyance speed of the first belt group 23.

Moreover, the thickness of each belt 23a-23d of the 1st belt group 23 is as shown in FIG.
The thickness of each belt 25 a to 25 e of the second belt group 25 is set to be thicker. That is, the driving roller 15, the first belt group 23, and the second belt 15 are set so that the first transport path PL1 and the second transport path PL2 have the same height at the connection position 55 as viewed in FIG. The belt group 25 is configured.

Here, a process in which the recording paper P is transported along the first transport path PL1 and the second transport path PL2 will be described with reference to FIG.

In the paper transport unit 4, the recording paper P is adsorbed and placed on the outer peripheral surfaces of the belts 23a to 23c of the first belt group 23 at the placement position 49, as shown in FIG. The The recording paper P is transported along the first transport path PL1 by the belts 23a to 23c at the transport speed of the first belt group 23. At this time, the recording paper P is held and conveyed on the outer peripheral surfaces of the belts 23a to 23c by the conveying force acting between the outer surfaces of the belts 23a to 23c.

Next, as shown in FIG. 3 (b), the recording paper P straddles the driving roller 15 from the outer peripheral surface of the belts 23 a to 23 c of the first belt group 23 at the connection position 55, and passes through the first belt group 2.
3 is gradually fed to the outer peripheral surfaces of the belts 25a to 25d of the second belt group 25 whose conveying speed is faster than 3. At this time, since the conveyance force of the recording paper P is dominated by the belts 23 a to 23 c, the moving speed in the X direction is dominated by the conveyance speed of the first belt group 23. During the period governed by the conveyance speed of the first belt group 23, the loading surface 9 of the recording paper P and the belt 25a.
Slip occurs between the outer peripheral surface of ˜25d.

Next, as shown in FIG. 3C, when the leading end portion 47 reaches the conveyance force change position 57,
The recording speed of the recording paper P is governed by the transport speed of the second belt group 25. At this time, the recording paper P is pulled by the belts 25 a to 25 d whose conveyance speed is faster than that of the first belt group 23, and slippage occurs between the outer peripheral surfaces of the belts 23 a to 23 c and the placement surface 9.

Next, as shown in FIG. 3 (d), the recording sheet P has its leading end 47 positioned at the separation position 53 as X.
When crossing the direction, the belts 25a to 25d are sequentially separated from the outer peripheral surfaces. And the rear end 5
When 1 is separated from the outer peripheral surfaces of the belts 25a to 25d at the separation position 53, one recording sheet P
The conveyance of is finished.

A flow of recording processing and recording operation in the inkjet recording apparatus 100 having the above-described configuration will be described.
In the inkjet recording apparatus 100, when the control unit 72 receives recording information from the host computer 79 via the interface unit 78, the CPU 721 starts the recording process shown in FIG.

In this recording process, first, in step S101, a conveyance unit drive command is output to the conveyance motor driver 74, and the first belt group 23 and the second belt group 25 are counterclockwise as viewed in FIG. The conveyance motor 13 is driven to rotate, and the process proceeds to step S102.

In step S102, a belt charging command is output to the charging power source driver 75, and an AC voltage is generated from each of the first charging power source 41 and the second charging power source 45, and step S1 is performed.
Move to 03.
In step S103, the count value Ct of the scale detection signal E1 is reset, and the process proceeds to step S104.

In step S104, a paper feed command is output to a paper feed unit (not shown), and one sheet of recording paper P is supplied from the paper feed unit to the gate roller 2, and the process proceeds to step S105. At this time, the recording paper P is abutted between the pair of rollers of the gate roller 2 and skew-corrected.

In step S105, a paper supply command is output to the paper feed motor driver 73, and the paper feed motor 3 is rotated so that the gate roller 2 rotates in the direction of feeding the recording paper P in the X direction as seen in FIG. The recording paper P is driven and supplied to the outer peripheral surfaces of the belts 23a to 23c of the first belt group 23, and the process proceeds to step S106.

In step S106, counting of the scale detection signal E1 input from the first linear encoder 29 is started, and the process proceeds to step S107. Here, counting the scale detection signal E1 indicates counting the number of times the scale detection signal E1 has changed from the Lo level to the Hi level.

In step S107, the scale detection signal E1 is used as the ejection timing signal TP.
Output of the discharge timing signal TP is started, and the process proceeds to step S108.

In this step S108, the count value Ct is determined whether reaches a predetermined value Ct _1, it is determined reaches the a (YES), there moves to step S109, not reached (NO
), The system waits until the count value Ct reaches a predetermined value Ct ₁ . Here, the predetermined value Ct ₁ is set so that the recording paper P has a first recording start position 8 from the placement position 49 as shown in FIG.
It is set to a value counted while being conveyed to 1.

In step S109, a first recording start command is output to the recording head driver 77 to start driving control of the head units 6a to 6d, and the first recording head 6 starts the first recording based on the recording information. Then, the process proceeds to step S110. In the first recording here, ejection of ink droplets is permitted based on the scale detection signal E1 as the ejection timing signal TP.

In step S110, the count value Ct is determined whether reaches a predetermined value Ct _2,
If it is determined reaches the a (YES), there moves to step S111, if it is determined not to reach (NO), and waits until the count value Ct reaches a predetermined value Ct _2. Here, the predetermined value C
t ₂ is set to a value counted while the recording paper P is conveyed from the placement position 49 to the second recording start position 83 as shown in FIG.

In step S111, a second recording start command is output to the recording head driver 77 to start driving control of the head units 7a to 7c, and the second recording head 7 starts the second recording based on the recording information. Then, the process proceeds to step S112. Also in the second recording here, ejection of ink droplets is permitted based on the scale detection signal E1 as the ejection timing signal TP.

In step S112, it is determined whether or not the sheet detection signal DP has changed from the Lo level to the Hi level. If it is determined that the sheet detection signal DP has changed (YES), the process proceeds to step S113, and it is determined that it has not changed (NO). Then, it waits until the paper detection signal DP changes from the Lo level to the Hi level.

In step S113, a phase correction value to be described later is calculated, and the process proceeds to step S114.

Here, the phase correction of the scale detection signal E2 in the inkjet recording apparatus 100 will be described.
In the ink jet recording apparatus 100, since the conveyance speed of the second belt group 25 is set to be higher than the conveyance speed of the first belt group 23, the cycle of the scale detection signal E1 and the scale detection signal E2 is set. Different. That is, the cycle C1 of the scale detection signal E1 and the cycle C2 of the scale detection signal E2 have a relationship of C1> C2, as shown in FIG.

Here, each of the period C1 and the period C2 corresponds to the recording resolution. That is, the transport distance of the recording paper P in the cycle C1 in the first belt group 23 and the transport distance of the recording paper P in the cycle C2 in the second belt group 25 are distances corresponding to the recording resolution. It has become. For example, when the recording resolution is 720 dpi (dot per inch), the distance corresponding to this recording resolution is about 0.035 mm.

Here, the rising edge E2 ₁ of the scale detection signal E2 occurs at time t1, the rising edge E1 ₁ of the scale detection signal E1 occurs at time t2, and the rising DP ₁ of the paper detection signal DP occurs at time t3. And The discharge timing signal T
Ejection timing TPa of P, since the occurrence time t2 is before the time t3, which is generated based on the rising E1 ₁ scale detection signal E1.

At this time, the conveyance distance d ₁ of the recording paper P at time S ₁ from time t2 to time t3 is:
It is calculated by the following equation (4).
d ₁ = v ₁ × S ₁ (4)
In this equation (4), v ₁ is the conveyance speed in the X direction of the first belt group 23.

The recording speed of the recording paper P conveyed by the first belt group 23 for the conveyance distance d ₁ is governed by the second belt group 25 at time t3. That is, when the distance corresponding to the recording resolution described above is Ds, when the recording paper P conveyed by the conveyance distance d ₁ is further conveyed by the distance of (Ds−d ₁ ) by the second belt group 25, If the discharge timing TPb is generated, the interval between the discharge timing TPa and the discharge timing TPb can correspond to the distance Ds.

The time S ₂ required to convey the distance (Ds−d ₁ ) by the second belt group 25 is as follows (
5).
S ₂ = (Ds−d ₁ ) / v ₂ (5)
In this equation (5), v ₂ is the conveyance speed in the X direction of the second belt group 25.

Accordingly, the phase correction value _SH is calculated by the following equation (6).
_{S H = S 2 - (C2} -S 3 -S 1) ... (6)
In this equation (6), S ₃ is the time from time t1 to time t2.

After calculating the phase correction value S _H, the scale detection signal E2 generated at time t4
From rising E2 _2, at the time of delaying the phase correction value S _H, first rising SP ₁ of the phase correction signal SP is generated. Then, after time t3, the phase correction signal SP is output from the control unit 72 as the ejection timing signal TP.

That is, the phase correction matches the interval between the ejection timing TPa immediately before the rising DP ₁ of the paper detection signal DP and the ejection timing TPb immediately after the rising DP ₁ of the paper detection signal DP with the interval corresponding to the recording resolution. That means.

Thus, in step S113 the recording process shown in FIG. 15, the phase correction value S _H, the above equation (4), the computed based on equation (5) and (6), proceeds to step S114 To do.

In step S114, starts generating a phase correction signal SP which is corrected based on the scale detection signal E2 to the phase correction value S _H, the process proceeds to step S115.

In this step S115, the scale detection signal E
From 1 to the scale detection signal E2, the process proceeds to step S116.

Here, the CPU 721 counts the scale detection signal E2 by adding the number of times the scale detection signal E2 has changed from the Lo level to the Hi level to the count value Ct before the count target is changed. For example, if the count target is changed from the scale detection signal E1 to the scale detection signal E2 at the time when the count value Ct of the scale detection signal E1 becomes 100, the subsequent counts from the Lo detection level of the scale detection signal E2 Each time the level is changed to the Hi level, the count value Ct of the scale detection signal E1 is incremented by one, such as 101, 102,.

In step S116, the output target as the ejection timing signal TP is changed from the scale detection signal E1 to the phase correction signal SP, and the process proceeds to step S117. Here, when the output target as the discharge timing signal TP is changed from the scale detection signal E1 to the phase correction signal SP, the discharge timing is changed from the discharge timing TPa based on the scale detection signal E1 to the discharge timing TPb based on the scale detection signal E2. Can be switched. Thereafter, the recording by the first recording head 6 and the second recording head 7 is continued at the discharge timing TPb.

In step S117, a paper discharge command is output to a paper discharge section (not shown), and the recording paper P on which recording has been completed is discharged to the outside of the ink jet recording apparatus 1 in step S118.
Migrate to
In this step S118, it is determined whether or not the recording of all of the recording information has been completed. If it is determined that the recording has ended (YES), the process proceeds to step S119, and if it is determined that the recording has not ended (NO). The process proceeds to step S103.

In step S119, a belt charging stop command is output to the charging power supply driver 75, the first charging power supply 41 and the second charging power supply 45 are stopped from generating AC voltage, and the process proceeds to step S120.
In step S120, a conveyance unit stop command is output to the conveyance motor driver 74 to stop the driving of the conveyance motor 13, and the process ends.

In the second embodiment, the processes in steps S113 and S114 in the recording process correspond to the phase correction unit, and the process in step S116 corresponds to the ejection timing switching unit.

In the inkjet recording apparatus 100 of the second embodiment, the outer diameter of the portion of the drive roller 15 around which the second belt group 25 is wound is larger than the outer diameter of the portion of the drive roller 15 around which the first belt group 23 is wound. Set to dimensions. For this reason, the conveyance speed in the second belt group 25 can be made faster than the conveyance speed of the first belt group 23.

Further, the attracting force acting per unit area of the recording paper P in the belts 25 a to 25 d of the second belt group 25 is the recording paper P in the belts 23 a to 23 c of the first belt group 23.
It is larger than the adsorption force acting per unit area.

As a result, the conveyance speed of the recording paper P in the first belt group 23 can be reliably changed to the conveyance speed in the second belt group 25 at the conveyance force change position 57.

When the leading end portion 47 of the recording paper P passes over the connection position 55 and is delivered to the outer peripheral surface of the second belt group 25, the recording paper P is transported by the second belt group 25 with the first conveying force. The belt slides on the outer peripheral surface of the second belt group 25 until the conveying force of the first belt group 23 is exceeded. At this time,
Since the recording paper P slides on the outer peripheral surface of the second belt group 25 so as to be pulled in the X direction,
Occurrence of wrinkles and the like is suppressed at a portion delivered to the outer peripheral surface of the second belt group 25. Accordingly, it is possible to transfer the recording paper P from the first belt group 23 to the second belt group 25 in a good state without occurrence of wrinkles.

The recording paper P is a second belt whose conveying speed is higher than that of the first belt group 23 from when the leading end 47 reaches the conveying force change position 57 until the trailing end 51 exceeds the connecting position 55. Group 2
5 slid on the outer peripheral surface of the first belt group 23. Therefore, the first transport path PL1
It is possible to suppress the occurrence of wrinkles or the like on the recording paper P between the first and second transport paths PL2.

That is, in the ink jet recording apparatus 100, the recording paper P does not generate wrinkles or the like until the rear end portion 51 is separated at the separation position 53 after the front end portion 47 is placed at the placement position 49. It is possible to stably convey in a stable state.

In the recording process in the inkjet recording apparatus 100, the phase correction is performed so that the interval between the ejection timing TPa and the ejection timing TPb becomes an interval corresponding to the recording resolution when the leading end portion 47 reaches the conveyance force change position 57. Is to be done. As a result, even when the transport speed on the first transport path PL1 and the transport speed on the second transport path PL2 are set to different speeds, it is possible to eject ink droplets at an appropriate ejection timing.

From the above, in the inkjet recording apparatus 100 according to the second embodiment, wrinkles and the like are generated after the front end portion 47 is placed at the placement position 49 until the rear end portion 51 is separated at the separation position 53. Ink droplets can be landed at an appropriate position on the recording surface 8 of the recording paper P conveyed in a suppressed and good state, and the recording quality can be further improved.

In the first and second embodiments, each of the head units 6a to 6d and 7a to 7c ejects four types of ink droplets of black, cyan, magenta, and yellow.
The configuration includes m, 63c, and 63k. However, the configuration is not limited thereto, and the configuration may be any type such as six types in which light cyan and light magenta colors are added.

In the first and second embodiments, the first recording head 6 and the second recording head 7 include head units 6a to 6d and 7a to 7c that are divided into a plurality of parts, and these head units 6a.
The nozzle rows for each color are configured when -6d and 7a-7c are virtually aligned in the Y direction. However, the form of the recording head is not limited to this, and straddles the recording paper P. The nozzle row formed over the length may be provided, and may be integrally formed for each color.

In the first and second embodiments, the nozzles 63y, 63m, 63c, and 63k of the head units 6a to 6d and 7a to 7c are arrayed along the Y direction. May be arranged along an arbitrary direction intersecting with. In this case, the nozzle pitch viewed from the X direction can be set short, and the recording resolution in the Y direction can be increased.

1 is an external view showing a main configuration of an ink jet recording apparatus according to a first embodiment of the present invention. FIG. 3 is a diagram illustrating a configuration of a paper transport unit of the ink jet recording apparatus according to the first embodiment of the present invention. FIG. 3 is a diagram illustrating a flow of recording paper conveyance in the ink jet recording apparatus according to the first embodiment of the present invention. FIG. 3 is a diagram illustrating a paper detection sensor of the ink jet recording apparatus according to the first embodiment of the present invention. FIG. 4 is a diagram illustrating a conveyance force change position in the ink jet recording apparatus according to the first embodiment of the present invention. FIG. 3 is a diagram illustrating the configuration of a first recording head and a second recording head of the ink jet recording apparatus according to the first embodiment of the present invention. FIG. 3 is a diagram illustrating an arrangement of nozzles of a first recording head and a second recording head of the ink jet recording apparatus according to the first embodiment of the present invention. 1 is a block diagram showing the main configuration of an ink jet recording apparatus according to a first embodiment of the present invention. FIG. 3 is a diagram illustrating a configuration of an ejection timing generation circuit of the ink jet recording apparatus according to the first embodiment of the present invention. 2 is a timing chart showing a signal flow of the ink jet recording apparatus according to the first embodiment of the present invention. FIG. 3 is a diagram illustrating a flow of recording processing of the ink jet recording apparatus according to the first embodiment of the present invention. FIG. 4 is a diagram illustrating a first recording start position and a second recording start position in the ink jet recording apparatus according to the embodiment of the present invention. The block diagram which shows the main structures of the inkjet recording device in 2nd Embodiment of this invention. AA sectional drawing in FIG.1 (b). The figure explaining the flow of the recording process of the inkjet recording device in 2nd Embodiment of this invention. 9 is a timing chart showing a signal flow of the ink jet recording apparatus according to the second embodiment of the present invention. The figure explaining the main structure of the conventional inkjet recording device. The figure explaining the subject of the conventional inkjet recording device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,100 ... Inkjet recording device, 4 ... Paper conveyance part, 5 ... Paper detection sensor, 6 ... 1st recording head, 7 ... 2nd recording head, 15 ... Drive roller, 23 ... 1st belt group, 25 ...
Second belt group, 23a, 23b, 23c, 23d, 25a, 25b, 25c, 25d,
25e ... belt, 29 ... first linear encoder, 31 ... second linear encoder, 35
... first belt charging unit, 37 ... second belt charging unit, 761 ... phase difference detection circuit, 762 ...
Phase shift circuit, 763... Switch circuit.

Claims (6)

An endless first conveying belt that conveys the recording medium is wound around a driving roller and is laid on the upstream side in the conveying direction of the recording medium from the driving roller to convey the recording medium. The second conveyor belt is wound around the drive roller so that the first conveyor belt and the first conveyor belt are alternately arranged in the axial direction of the drive roller, and is directed further downstream in the transport direction than the drive roller. A recording medium conveying means having a construction erected,
Nozzles for ejecting ink droplets are formed, and the recording medium transported by the recording medium transporting unit is formed on the recording surface opposite to the surface on the side on which the first and second transport belts are placed. The recording is configured such that the ink droplets are ejected at the ejection timing permitted to eject the ink droplets, and a plurality of dots arranged in a line in a direction orthogonal to the transport direction can be formed without moving. Head,
A first timing generation unit that generates the first ejection timing based on the rotation amount of the first conveyance belt;
A second timing generation unit that generates the second ejection timing based on the rotation amount of the second transport belt;
The recording medium fed from the first conveyance belt to the second conveyance belt across the drive roller has a conveyance force of the recording medium at the second conveyance belt at the first conveyance belt. A recording medium detection means for detecting that the conveyance force change position, which is a position where the conveyance force is exceeded, is reached;
Discharge timing switching means for switching the discharge timing from the first discharge timing to the second discharge timing based on the fact that the recording medium detection means detects the arrival of the recording medium at the conveyance force change position; ,
Phase correction means for correcting a phase of the second ejection timing with respect to the first ejection timing when the recording medium detection means detects the arrival of the recording medium at the transport force change position. An ink jet recording apparatus. The second conveying belt is configured such that the conveying force per unit area of the recording medium on the second conveying belt is larger than the conveying force per unit area of the recording medium on the first conveying belt. 2. The ink jet recording apparatus according to claim 1, further comprising a friction force increasing means for increasing a friction force acting between the conveying belt and the recording medium. The frictional force increasing means includes belt charging means for charging the second transport belt, and is configured to increase the frictional force by attracting the recording medium to the charged second transport belt. The ink jet recording apparatus according to claim 2, wherein: 4. The second conveying belt according to claim 1, wherein a conveying speed for conveying the recording medium is set to be faster than the conveying speed of the first conveying belt. The ink jet recording apparatus according to one item. The conveying speed is such that the outer diameter of the portion around which the second conveying belt of the driving roller is wound is
By setting the outer diameter of the portion around which the first conveyor belt is wound to be larger than that of the first conveyor belt, the second conveyor belt is set at a speed higher than that of the first conveyor belt. The ink jet recording apparatus according to claim 4, wherein Phase difference detection means for detecting a phase difference between the first discharge timing and the second discharge timing;
The phase correction means is based on the phase difference detected by the phase difference detection means,
When the recording medium detection means detects arrival of the recording medium at the conveyance force change position,
4. The inkjet recording apparatus according to claim 1, wherein the phase of the second ejection timing with respect to the first ejection timing is corrected. 5.

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