JP2000272111A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To record images to both of faces of a recording medium by setting a first head part for discharging ink liquid drops to one face of the transferred recording medium and, a second head part for discharging ink liquid drops to the other face of the recording medium. SOLUTION: A first and a second head parts 107 and 109 for discharging ink liquid drops to an upper and a lower faces of a recording medium 101 transferred in the vicinity of pairing rollers 102, 103 and transfer rollers 104, 105 are set between the roller pairs via a minute space to the recording medium 101 respectively. The first, second head part 107: 109 is constituted of linear heads 111, 113, 115, 117 and 119: 121, 123, 125, 127 and 129 for discharging ink of different colors. A plurality of nozzles of each head part are arranged in a breadthwise direction of the recording medium 101 so that the ink liquid drops discharged from the head parts 107 and 109 will not hit an equal point of the recording medium at the same time. Image-formed faces are dried by a first and a second driers 141 and 143.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ink jet printer which forms an image on a recording medium by discharging ink droplets onto the recording medium.

[0002]

2. Description of the Related Art FIG. 6 is a view showing a line type ink jet printer as a conventional ink jet printer.

In the line type ink jet printer 1, a recording paper P as a recording medium is sandwiched between a pair of conveying rollers 31 and 32 of a conveying mechanism 3 and further driven by a pair of conveying rollers 31 rotated by a conveying motor 33 in FIG. It is designed to be transported in the Y direction.

[0006] A line head 2 is provided between the pair of transport rollers 31 and 32 so as to face one surface PS of a recording sheet P as a recording medium. Line head 2
It is connected via a flexible flat cable (hereinafter referred to as FFC) 4 to a control board 51 provided with a control unit.

Next, the line head will be described with reference to FIG. As shown in the figure, the line head 2 is
4 and a lid substrate 25. The piezoelectric elements 22 are arranged in a row on the base substrate 24, and each of the piezoelectric elements 22 is connected to the FFC 4 via a circuit conductor 23.

[0006] On the lid substrate 25, nozzles 21 forming pairs with the respective piezoelectric elements 22 are formed in a line at the same pitch, and each nozzle 21 is connected to a thin tube provided with a place for receiving the ink discharge pressure by the piezoelectric elements 22. , This thin tube is the lid substrate 25
Are connected to the ink tank provided in the printer.

Next, the operation of the above configuration will be described. The control unit on the control board 51 transports the recording paper P at a constant speed by the transport mechanism 3, drives the piezoelectric element 22 according to the image signal, and collects the ink from the nozzle 21 of the line head 2 one line at a time. The droplet is ejected to form an image on the recording paper P.

[0008]

However, the ink jet printer as shown in FIG. 6 has a problem that the printing speed (image forming speed) is low and the ink dries poorly.

Therefore, there is no ink jet printer that records an image on both sides of the recording paper P. The present invention has been made in view of the above problems, and an object of the present invention is to provide an ink jet printer that can record an image on both sides of a recording medium.

[0010]

According to a first aspect of the present invention, there is provided an image forming apparatus, comprising: a first head for discharging ink droplets onto one surface of a recording medium to be conveyed; A second ejecting ink droplet onto the other surface of the medium;
And an ink jet printer.

[0011] With respect to one surface of the conveyed recording medium,
An image is recorded on both sides of a recording medium by having a first head unit that ejects ink droplets and a second head unit that ejects ink droplets on the other surface of the recording medium. be able to.

According to a second aspect of the present invention, in the first aspect of the present invention, the first head and the second head are
An ink jet printer comprising a plurality of heads for emitting ink droplets of different colors.

The first head unit and the second head unit include a plurality of heads that emit ink droplets of different colors, so that a color image can be recorded on both sides of a recording medium. .

According to a third aspect of the present invention, there is provided an ink jet printer according to the first or second aspect, wherein the first head unit and the second head unit have a plurality of nozzles. is there.

Since the first head and the second head have a plurality of nozzles, the image forming speed is improved. The invention according to claim 4 is the invention according to claims 1 to 3
The ink droplets ejected from the first head portion and the ink droplets ejected from the second head portion of the invention according to any one of the above, do not strike the same portion of a recording medium at the same time. An ink jet printer characterized by the following.

The ink droplets ejected from the first head unit and the ink droplets ejected from the second head unit do not hit the same portion of the recording medium at the same time. When the tension acts, it is possible to prevent the strength of the recording medium from being locally reduced and the recording medium from being broken.

According to a fifth aspect of the present invention, the ink ejection surfaces of the first head unit and the second head unit according to any one of the first to fourth aspects are not in contact with the recording medium. An ink jet printer characterized in that:

Since the ink ejection surfaces of the first head unit and the second head unit are not in contact with the recording medium, it is possible to prevent the surface of the recording medium from being stained by rubbing. According to a sixth aspect of the present invention, a positioning means for positioning the recording medium is provided at least near the upstream of the first head unit and the second head unit according to the first aspect of the invention. An ink jet printer, wherein a distance between the ink ejection surfaces of the first and second head units and the recording medium is set to a minimum distance at which ink is formed into droplets.

Positioning means for positioning the recording medium is provided at least in the vicinity of the first head section and the second head section, and the ink ejection surfaces of the first and second head sections and the recording section. By setting the distance from the medium to the minimum distance at which the ink is formed in the droplet, the displacement of the landing position of the ink droplet on the recording medium is reduced, and the deterioration of the image quality is minimized.

As the positioning means, the first and second heads are provided with projections to which the recording medium can slide, the pair of rollers for sandwiching the recording medium, and the floating of the recording medium by electrostatic force.
There are means for holding, but there is no limitation.

According to a seventh aspect of the present invention, the first head portion and the second head portion of the first aspect of the present invention are provided.
A drying unit for drying a recording surface of the recording medium, provided downstream of the head unit.

A drying means for drying the recording surface of the recording medium is provided downstream of the first head section and the second head section, so that the ink on the recording medium can be dried more quickly. Can be prevented from being stained by rubbing of the surface.

The drying means includes, but is not limited to, means for drying using infrared rays, far infrared rays, hot air, vacuum or the like. According to an eighth aspect of the present invention, a protective layer is formed on the recording surface of the recording medium downstream of the first head unit and the second head unit according to the first aspect of the invention. An ink jet printer comprising a protective layer forming means.

[0024] By providing a protective layer forming means for forming a protective layer on the recording surface of the recording medium downstream of the first head unit and the second head unit, dirt due to rubbing of the surface of the recording medium is provided. Can be prevented.

As a means for forming a protective layer, there is a means for emitting a transparent resin solution to a recording medium and forming a laminate layer on both sides of the recording medium, but is not limited thereto. Claim 9
The invention described in the above is an ink jet printer, wherein the recording medium according to any one of the first to eighth aspects is conveyed in a substantially horizontal direction.

By transporting the recording medium in a substantially horizontal direction, the ink droplets can be emitted in the same direction as the direction of gravity or in the opposite direction, and the influence of gravity is only in the direction parallel to the direction of emission of the ink droplets. The trajectory of the ink droplet is hardly bent or shaken.

Therefore, the landing accuracy of the ink on the recording medium can be improved. Conventional horizontal conveyance and recording from one direction can be used, and no major changes are required.
A simple configuration can be achieved.

The invention according to claim 10 is the invention according to claims 1 to 8
The recording medium according to any one of the above aspects, is conveyed in a substantially vertical direction.

Since the recording medium is conveyed in a substantially vertical direction, slack during conveyance is eliminated, the displacement of ink droplet landing positions on the recording medium is reduced, and deterioration of image quality is minimized. Can be

Further, since the ink is filled in the head portion, bubbles are apt to be mixed in from the nozzle from which the ink droplet is discharged. In this case, the bubble moves upward, stays in the head portion, and does not come out of the nozzle and adversely affect the formed image.

When air bubbles are generated in the head portion, the ink in the head portion is sucked from the nozzles to remove the air bubbles. However, since the first and second head portions are arranged substantially horizontally, the air bubbles are generated. Remains in the vicinity of the nozzle, and the ink suction amount is small.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the drawings. (First Embodiment) A first embodiment will be described with reference to FIG. In the drawing, reference numeral 201 denotes a recording medium which is nipped and conveyed by a roller 202 as a positioning means and a pair of conveying rollers 204 and 205 in a substantially horizontal direction (direction of arrow A) with a predetermined pulling force (tension).

Since an image is formed on both sides of the recording medium 101 of the present embodiment, it is preferable that a layer for preventing ink bleeding is formed at the center in the thickness direction. Roller pairs 102 and 103 and transport roller pairs 104 and 1
In the vicinity of the pair of rollers 102 and 103 and the pair of transport rollers 104 and 105,
01 with respect to one surface (the upper surface in the present embodiment)
A first head unit 107 that ejects ink droplets, and a second head unit 109 that ejects ink droplets to the other surface (the lower surface in this embodiment) of the recording medium 101 are:
The recording medium 101 is arranged via a minute space.

The first head unit 107 includes a plurality of linear heads (five heads in the present embodiment) for ejecting inks of different colors 111, 113, 115, 117, and 11.
It consists of nine.

Similarly to the first head unit 107, the second head unit 109 includes a plurality of heads (five heads in this embodiment) 121 and 12 for ejecting inks of different colors.
3,125,127,129.

Further, as shown in FIG. 2, which is a view of the head 119 in the direction of arrow B, the ink ejection surface of the head 119 has
A plurality of nozzles 119 across the width direction of the recording medium 101
a is provided.

Other heads 113 to 119 and 121 to 1
Similarly, a plurality of nozzles 29 are provided in the width direction of the recording medium 101. In the present embodiment,
The first and second ink droplets ejected from the first head unit 107 and the second ink droplet ejected from the second head unit 109 do not strike the same portion of the recording medium at the same time. Each of the heads 111 to 119 of the head units 107 and 109
And nozzles 121 to 129 are provided.

First head 107, second head 1
09 and a pair of conveying rollers 104 and 105, a first dryer 141 and a second dryer 143 are provided as drying means for drying the image forming surface of the recording medium 101 on which an image is formed. I have.

The first and second dryers 141 and 143 are not limited to those dried by using infrared rays, far infrared rays, hot air, vacuum, or the like. In the ink jet printer according to the present embodiment, the speed of ink droplets ejected downward from the first head unit 107 and the speed of ink droplets ejected upward from the second head unit 109 are determined. In the same manner, the dot diameter (pixel diameter) formed on the upper surface of the recording medium 101 by the ink droplets discharged from the first head unit 107 and the ink droplets discharged from the second head unit 109 The drive voltage and frequency to the first head unit 107 and the second head unit 107 are controlled so that the dot diameter formed on the lower surface of the recording medium 101 is the same.

According to such a configuration, the following effects can be obtained. (1) By transporting the recording medium 101 in a substantially horizontal direction, the ink droplets can be emitted in the same or opposite direction to the direction of gravity, and the influence of gravity is only in the direction parallel to the direction of emission of the ink droplets. The trajectory of the ink droplet is hardly bent or shaken.

Accordingly, it is possible to improve the landing accuracy of the ink on the recording medium. Conventional horizontal conveyance and recording from one direction can be used, and no major changes are required.
A simple configuration can be achieved.

(2) Recording medium 10 conveyed in a substantially horizontal direction
A first head 107 that ejects ink droplets to one surface of the recording medium 101;
With the provision of the second head unit 109 for discharging ink droplets, images can be recorded on both surfaces of the recording medium 101.

(3) The first head unit 107 and the second head unit 109 are composed of a plurality of heads 111 to 119 and heads 121 to 129 for emitting ink droplets of different colors. A color image can be recorded on both sides of the image 101.

(4) Since the first head unit 107 and the second head unit 109 have a plurality of nozzles, the image forming speed is improved. (5) The ink droplets ejected from the first head unit 107 and the ink droplets ejected from the second head unit 109 do not hit the same portion of the recording medium 101 at the same time, so that the recording medium When the tension acts on the recording medium 101, it is possible to prevent the strength of the recording medium 101 from locally decreasing and breaking.

(6) Since the ink ejection surfaces of the first head unit 107 and the second head unit 109 are not in contact with the recording medium 101, the surface of the recording medium 101 can be prevented from being stained by rubbing.

(7) A pair of rollers 102, 10 as positioning means for positioning the recording medium 101 near the upstream and downstream of the first head 107 and the second head 109.
3 and 104 and 105, and the distance between the ink ejection surfaces of the first and second head units 107 and 109 and the recording medium 101 is set to the minimum distance in which ink is formed into droplets. The displacement of the landing position of the droplet on the recording medium 101 is reduced, and the deterioration of the image quality is minimized.

(8) Downstream of the first head 107 and the second head 109, first and second dryers 141 and 1 as drying means for drying the recording surface of the recording medium 101 are provided.
Providing the ink 43 allows the ink on the recording medium 101 to be dried more quickly, and prevents the surface of the recording medium 101 from being stained by rubbing.

The present invention is not limited to the above embodiment. For example, in FIG.
Heads 107, 109 and these heads 107, 1
A protective layer forming means for forming a protective layer on the recording surface of the recording medium 101 is provided between the pair of conveying rollers 104 and 105 downstream of the recording medium 09 to prevent the surface of the recording medium from being stained by rubbing. Good.

As a means for forming a protective layer, there is a means for emitting a transparent resin solution to a recording medium and forming a laminate layer on both sides of the recording medium, but is not limited thereto. As positioning means, the roller pairs 102, 103 and 104, 1
05 was used, but is not limited to this. For example, as shown in FIG. 3, instead of the roller pairs 102 and 103, protrusions 161 and 163 with which the recording medium 101 slides may be formed on the upstream side of the first and second head portions 107 and 109. .

As shown in FIG. 4, at least one of the heads of the first and second head portions 107 and 109 is provided.
One of the heads (the head 119 and the head 129 in the present embodiment) may be provided with a projection 165 with which a portion other than the image area of the recording medium 101 slides.

Further, instead of the pair of conveying rollers, compressed air is blown obliquely onto the recording medium 101 so that the recording medium 101
May be conveyed while positioning. Furthermore,
A recording medium 101 is provided downstream of the pair of transport rollers 104 and 105.
A heating roller or a pressure roller for removing the curl may be provided. (Second Embodiment) A second embodiment will be described with reference to FIG.

In the drawing, reference numeral 201 denotes a recording medium which is nipped and conveyed by a roller 202 as a positioning means and a pair of conveying rollers 204 and 205 with a predetermined pulling force (tension) in a vertical direction (direction of arrow C).

Since an image is formed on both sides of the recording medium 201 of the present embodiment, it is preferable that a layer for preventing ink bleeding is formed at the center in the thickness direction. Between the roller 202 and the transport roller pair 204, 205, the roller 202 and the transport roller pair 204, 20
5, a first head unit 207 that ejects ink droplets to one surface of the recording medium 201 to be conveyed;
A second head unit 209 for ejecting ink droplets is arranged on the other surface of the recording medium 201 via a minute space with respect to the recording medium 201.

The first head unit 207 includes a plurality of linear heads (five heads in the present embodiment) 211, 213, 215, 217, and 21 for ejecting inks of different colors.
It consists of nine.

Similarly to the first head unit 207, the second head unit 209 has a plurality of heads (five heads in this embodiment) 221 and 22 that eject inks of different colors.
3,225,227,229.

Further, as in the case of the first embodiment, the first
And each of the heads 211 to 211 of the second head units 207 and 209
219 and 221 to 229 are provided with a plurality of nozzles over the width direction of the recording medium 201.

In this embodiment, the ink droplets discharged from the first head unit 207 and the second head unit 2
The ink droplets ejected from the first and second head units 207, 209, and 209 and 22 are arranged so as not to strike the same portion of the recording medium 201 at the same time.
The nozzles 1 to 229 are provided.

First head unit 207, second head unit 2
09 and a pair of conveying rollers 204 and 205, a first dryer 241 and a second dryer 243 as drying means for drying an image forming surface of the recording medium 201 on which an image is formed are provided. I have.

According to such a configuration, the following effects can be obtained. (1) By transporting the recording medium 201 in a substantially vertical direction, slack during transport of the recording medium 201 is eliminated, the displacement of ink droplet landing positions on the recording medium 201 is reduced, and deterioration of image quality is minimized. Can be kept to a minimum.

The first and second head sections 207, 20
9 is filled with ink, and air bubbles are likely to be mixed in from nozzles from which ink droplets are ejected. In this case, the bubbles move upward, and the first and second head units 207 and 209
Within the nozzle and does not come out of the nozzle and adversely affect the formed image.

When bubbles are generated in the first and second head units 207 and 209, the first and second head units 20
7 and 209, the air bubbles are removed by sucking the ink in the nozzles from the nozzles.
Since 09 is arranged substantially horizontally, the air bubbles remain near the nozzle, and the ink suction amount is small.

Further, in the first embodiment, since the head portion is arranged in the vertical direction, the speed of the ink droplet ejected downward from the first head portion 107 and the speed of the second head portion 109 The speed of the ink droplets ejected upward is the same, and the diameter of the dot formed on the upper surface of the recording medium 101 by the ink droplets ejected from the first head unit 107
The first head unit 107 and the second head unit 107 are configured such that the (pixel diameter) and the dot diameter formed on the lower surface of the recording medium 101 by the ink droplets ejected from the second head unit 109 are the same.
Although it was necessary to control the drive voltage and frequency to the head unit 107, in the present embodiment, since the first and second head units 207 and 209 were arranged in the horizontal direction, such control was not performed. It becomes unnecessary.

(2) Recording medium 20 conveyed in a substantially vertical direction
A first head unit 207 that ejects ink droplets to one surface of the recording medium 201;
By providing the second head unit 209 for discharging ink droplets, an image can be recorded on both surfaces of the recording medium 201.

(3) The first head unit 207 and the second head unit 209 are composed of a plurality of heads 211 to 219 and heads 221 to 229 which emit ink droplets of different colors. A color image can be recorded on both surfaces of the image 201.

(4) Since the first head unit 207 and the second head unit 209 have a plurality of nozzles, the image forming speed is improved. (5) The ink droplets ejected from the first head unit 207 and the ink droplets ejected from the second head unit 209 do not strike the same portion of the recording medium 201 at the same time, so that the recording medium When the tension acts on the recording medium 101, it is possible to prevent the strength of the recording medium 101 from locally decreasing and breaking.

(6) Since the ink ejection surfaces of the first head unit 207 and the second head unit 209 are not in contact with the recording medium 201, the surface of the recording medium 201 can be prevented from being stained by rubbing.

(7) A roller 202 and a pair of conveying rollers 204 and 205 as positioning means for positioning the recording medium 201 are provided near the upstream and downstream of the first head unit 207 and the second head unit 209. By setting the distance between the ink ejection surfaces of the second head units 207 and 209 and the recording medium 201 to be the minimum distance at which ink is formed into droplets, the ink droplets land on the recording medium 201. The displacement is small, and the deterioration of the image quality is minimized.

(8) Downstream of the first head unit 207 and the second head unit 209, first and second dryers 241 and 2 as drying means for drying the recording surface of the recording medium 201 are provided.
By providing the ink 43, the ink on the recording medium 201 can be dried more quickly, and the surface of the recording medium 201 can be prevented from being stained by rubbing.

[0069]

As described above, according to the first aspect of the present invention, the first head unit for discharging ink droplets onto one surface of the recording medium to be conveyed, and the recording medium With the second head unit for discharging ink droplets on the other surface of the recording medium, images can be recorded on both surfaces of the recording medium.

According to the second aspect of the present invention, the first head unit and the second head unit are composed of a plurality of heads that emit ink droplets of different colors, so that Color images can be recorded on both sides.

According to the third aspect of the present invention, since the first head unit and the second head unit have a plurality of nozzles, the image forming speed is improved. Claim 4
According to the invention described above, the ink droplets ejected from the first head unit and the ink droplets ejected from the second head unit do not hit the same portion of the recording medium at the same time. , When tension is acting on the recording medium,
It is possible to prevent the strength of the recording medium from locally decreasing and breaking.

According to the fifth aspect of the present invention, since the ink ejection surfaces of the first head unit and the second head unit are not in contact with the recording medium, the surface of the recording medium is rubbed. Contamination can be prevented.

According to the invention of claim 6, positioning means for positioning the recording medium is provided at least near the upstream of the first head portion and the second head portion,
By setting the distance between the ink ejection surfaces of the first and second head units and the recording medium to be a minimum distance at which ink is formed into droplets, the landing positions of the ink droplets on the recording medium Is small, and deterioration of image quality is minimized.

According to the seventh aspect of the present invention, a drying means for drying the recording surface of the recording medium is provided downstream of the first head section and the second head section. Can be dried more quickly, and stains due to rubbing of the surface of the recording medium can be prevented.

According to the present invention, a protection layer forming means for forming a protection layer on a recording surface of the recording medium is provided downstream of the first head section and the second head section. Accordingly, it is possible to prevent dirt due to rubbing of the surface of the recording medium.

According to the ninth aspect of the present invention, by transporting the recording medium in a substantially horizontal direction, the ink droplets can be emitted in the same direction as the gravity direction or in the opposite direction, and the influence of gravity can be reduced. Since the direction is only the direction parallel to the direction, the trajectory of the ink droplet is hardly bent or blurred.

Therefore, it is possible to improve the landing accuracy of the ink on the recording medium. According to the tenth aspect of the present invention, the recording medium is conveyed in a substantially vertical direction, so that slack during conveyance is eliminated, the displacement of ink droplet landing positions on the recording medium is reduced, and image quality is improved. Degradation is minimized.

Further, since the ink is filled in the head portion, bubbles are apt to be mixed in from the nozzle from which the ink droplet is discharged. In this case, the bubble moves upward, stays in the head portion, and does not come out of the nozzle and adversely affect the formed image.

When bubbles are generated in the head portion, the ink in the head portion is suctioned from the nozzles to remove the bubbles. However, since the first and second head portions are arranged substantially horizontally, the bubbles are removed. Remains in the vicinity of the nozzle, and the ink suction amount is small.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment.

FIG. 2 is a view of the head in FIG.

FIG. 3 is a diagram illustrating another embodiment.

FIG. 4 is a diagram illustrating another embodiment.

FIG. 5 is a diagram showing a second embodiment.

FIG. 6 is a diagram illustrating a line-type inkjet printer as a conventional inkjet printer.

FIG. 7 is a diagram illustrating the line head of FIG. 6;

[Explanation of symbols]

 101 recording medium 107 first head unit 109 second head unit

Claims (10)

[Claims] A first head for discharging ink droplets on one surface of a recording medium being conveyed; and a second head for discharging ink droplets on the other surface of the recording medium. An ink jet printer, comprising: a head portion; 2. The ink-jet printer according to claim 1, wherein the first head unit and the second head unit include a plurality of heads that emit ink droplets of different colors. 3. The ink jet printer according to claim 1, wherein the first head unit and the second head unit have a plurality of nozzles. 4. An ink droplet ejected from the first head unit and an ink droplet ejected from the second head unit do not strike the same portion of a recording medium at the same time. The inkjet printer according to any one of claims 1 to 3. 5. The ink jet printer according to claim 1, wherein the ink ejection surfaces of the first head unit and the second head unit are not in contact with the recording medium. Printer. 6. A positioning means for positioning the recording medium at least near the upstream of the first head unit and the second head unit, and an ink ejection surface of the first and second head units; 5. The ink jet printer according to claim 1, wherein a distance from the recording medium is set to a minimum distance at which ink is formed in a droplet. 7. The recording medium according to claim 1, further comprising a drying unit provided downstream of the first head unit and the second head unit for drying a recording surface of the recording medium. The ink-jet printer as described. 8. A protection layer forming means for forming a protection layer on a recording surface of the recording medium is provided downstream of the first head section and the second head section. 8. The ink jet printer according to any one of items 7. 9. The ink jet printer according to claim 1, wherein the recording medium is conveyed in a substantially horizontal direction. 10. The ink jet printer according to claim 1, wherein the recording medium is conveyed in a substantially vertical direction.