JPH09123432A - Transfer ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a high quality print image by providing a transfer ink jet recorder with an ink image forming means for sticking jetted ink droplet onto the surface of an intermediate transfer body while separating from each other thereby preventing a plurality of ink droplets from combining onto the surface of intermediate transfer body. SOLUTION: In the ink jet recorder, a recording head 12 forms an ink image on the circumferential surface of an intermediate transfer body 11 and the ink image is transferred onto a paper carried on a paper carrying path 14 from a paper feed cassette 13. At the time of printing, the nozzle face of recording head 12 is located at a printing position of specified dimension, e.g. 1mm, from the surface of intermediate transfer body 11 and ink, filling an ink liquid chamber, is pressurized by a pressurizing chamber and jetted toward the intermediate transfer body 11 to adhere on the surface thereof thus forming an ink image. In this regard, the ink droplets are separated from each other by a specified method on the surface of intermediate transfer body 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus applied to a facsimile, a copying machine, a printer, etc., and more particularly to a transfer type for transferring an ink image formed on an intermediate transfer member to a recording medium for printing. The present invention relates to an inkjet recording device.

[0002]

2. Description of the Related Art Conventionally, a direct type ink jet recording apparatus for ejecting ink droplets directly from a plurality of nozzles arranged in a recording head onto a recording sheet to perform printing, and an ink droplet ejecting toward an intermediate transfer member. There is known a transfer type ink jet recording apparatus that forms an ink image by transferring the ink image onto a recording sheet to perform printing. In the direct type ink jet recording apparatus, when the recording sheet bends, the nozzle surface of the recording head comes into contact with and becomes dirty. Therefore, it is necessary to consider prevention of bending of the recording sheet.
Such a consideration is not necessary, and it is possible to easily keep the distance between the nozzle of the recording head and the intermediate transfer body constant.

[0003]

The intermediate transfer member used in the above transfer type ink jet recording apparatus may be made of metal or synthetic resin as a material, but the aqueous ink usually used in the above direct type ink jet recording apparatus is used. When ejected toward an intermediate transfer body made of metal or synthetic resin, if the ejected ink droplets come into contact with adjacent ink droplets, they will coalesce due to surface tension and the ink droplets will become a large ball, forming an ink image. The print quality was deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a transfer type ink jet recording apparatus capable of obtaining a high quality printed image.

[0005]

According to the present invention, ink droplets are ejected from nozzles formed at a constant pitch on a recording head toward the surface of an intermediate transfer member according to print data and adhered to the surface of the intermediate transfer member. In the transfer-type inkjet recording device that forms an ink image by the transfer and transfers the ink image to a recording medium that is conveyed to perform printing, an ink image that is attached to the surface of the intermediate transfer member so that the ejected ink droplets are separated from each other. It is provided with a forming means (Claim 1).

According to this structure, since the ink image is formed such that the ink droplets attached to the surface of the intermediate transfer member are separated from each other, a plurality of ink droplets will not coalesce on the surface of the intermediate transfer member. High quality printed images can be obtained.

Further, the ink image forming means sets the diameter of the adhered ink droplet to a value less than the constant pitch (claim 2).

According to this structure, the ink droplets adhering to the surface of the intermediate transfer member are reliably separated from the adjacent ink droplets, so that a plurality of ink droplets do not coalesce on the surface of the intermediate transfer member, and high quality is achieved. The printed image of is obtained.

The intermediate transfer member includes a first intermediate transfer member and a second intermediate transfer member located downstream of the first intermediate transfer member in the transport direction.
The intermediate transfer member, the recording head includes first and second recording heads for ejecting ink droplets toward the first and second intermediate transfer members, and the ink image forming unit includes There is provided a dividing unit that distributes and ejects the ink droplets adjacent to each other in the direction orthogonal to the transport direction to the first recording head and the second recording head (claim 3).

According to this structure, the ink droplets which are adjacent to each other in the direction orthogonal to the recording medium conveyance direction are distributed and ejected to the first recording head and the second recording head.
The ink droplets attached to the surfaces of the first intermediate transfer body and the second intermediate transfer body are surely separated from the adjacent ink droplets, and a plurality of ink droplets are formed on the surfaces of the first and second intermediate transfer bodies. Therefore, a high quality printed image can be obtained.

[0011]

1 is a front view showing the internal structure of a first embodiment of an ink jet recording apparatus according to the present invention. This inkjet recording apparatus is provided with an intermediate transfer member 11
A recording head 12 facing the intermediate transfer body 11 is provided, and an ink image is formed on the peripheral surface of the intermediate transfer body 11 by the recording head 12, and the ink image is passed from a paper feed cassette 13 via a paper transport path 14. Printing is performed by transferring to a sheet as a recording medium that is conveyed.

The paper feed cassette 13 stores recording paper of a predetermined size to which an image is transferred, and a paper feed roller 15 for feeding paper is arranged at the front end. The sheet conveying path 14 has a guide for guiding the sheet fed from the sheet feeding cassette 13 to the intermediate transfer body 11, and has a pair of conveying rollers 16 for conveying the fed sheet and a pair of registration rollers for performing the secondary sheet feeding. 17 are provided.

The intermediate transfer member 1 is provided downstream of the paper transport path 14.
1 is provided, and a sheet conveying path 18, a discharge roller pair 19 and a discharge tray 20 are provided downstream of the intermediate transfer body 11.

The intermediate transfer member 11 has, for example, a cylindrical drum shape, and an elastic layer made of, for example, silicone rubber or fluororubber is formed on the surface thereof. A recording head 12, a pressure roller 21, and a cleaning device 22 are arranged around the intermediate transfer member 11.

The recording head 12 has a nozzle surface formed on the surface facing the intermediate transfer body 11, and ejects ink droplets from the nozzles to form an ink image on the intermediate transfer body 11. Each nozzle is, for example, a sheet of paper. A large number of sheets are formed in the width direction at least for the width of the paper, and each is connected to a pressurizing chamber (not shown), and each pressurizing chamber is connected to an ink liquid chamber (not shown) in which ink is further stored. Ink is supplied to the ink liquid chamber from the ink tank 23 arranged in the above through the ink supply tube 24.

Further, in the recording head 12, the nozzle surface is arranged at a printing position of a predetermined dimension of, for example, 1 mm from the surface of the intermediate transfer body 11 at the time of printing, and the ink filled from the ink liquid chamber is pressurized by the pressure chamber. Intermediate transfer body 1 from each nozzle
1 is ejected toward the surface of the intermediate transfer body 11, and ink droplets adhere to the surface of the intermediate transfer body 11 to form an ink image. At this time, the ink droplets adhering to the surface of the intermediate transfer member 11 are separated from each other by the method described later.

The pressure roller 21 is disposed above the intermediate transfer member 11 so that its peripheral surface is in contact with the intermediate transfer member 11, and applies a required pressure to the contact portion.
The recording paper sandwiched between 1 and the pressure roller 21 is transferred by the applied pressure to the ink image formed on the surface of the intermediate transfer body 11 while being conveyed.

The cleaning device 22 removes the ink remaining on the surface of the intermediate transfer body 11 after the transfer, and is composed of a felt roller 221, a cleaning roller 222, and a take-up roller 223.

The felt roller 221 has a cleaning member 224 wound around it.
4 is made of felt, non-woven fabric or the like, and has a width of at least the size of the nozzle row of the recording head 11. A cleaning member 224 is stretched around the cleaning roller 222, and the cleaning roller 222 is arranged to be pressed against the surface of the intermediate transfer body 11 with a pressure that does not hinder the rotation of the intermediate transfer body 11. Take-up roller 2
The cleaning roller 222 is rotated by rotating the cleaning roller 222.
The cleaning member 224 stretched around the reel is wound up from the felt roller 221 and rotated at a required rotation speed.
The ink remaining on the surface of the intermediate transfer body 11 is wiped off by the cleaning member 224. The take-up roller 223 may be intermittently rotated at a required interval by a required size.

The control unit 30 is composed of a CPU or the like, and controls the nozzles for ejecting ink droplets from the recording head 12 in accordance with print data. Further, the diameter of the ink droplets ejected from the nozzles of the recording head 12 is controlled.

Next, referring to FIG. 2, a method for making ink droplets attached to the surface of the intermediate transfer member 11 separate from each other.
Will be described. 2A and 2B are diagrams showing ink droplets adhering to the surface of the intermediate transfer member 11, FIG. 2A is a plan view illustrating the size of the ink droplets, and FIG. 2B is a diagram showing a state in which the ink droplets are viewed from the side. .

Controlling the Diameter of Ink Droplets Assuming that the diameter R of the ink droplets 120 ejected from the recording head 12 to the intermediate transfer member 11 is D (the nozzle pitch of the recording heads 12), the diameter R of the ejected ink droplets 120 will be As shown in a), R <D. For example, in the case of a type that pressurizes the pressurizing chamber by deformation of the piezoelectric element arranged on one side wall of the pressurizing chamber, the controller 30 adjusts the voltage value applied between the electrodes of the piezoelectric element. , Control the diameter of the ejected ink droplet 120.

Increasing the surface tension of the ink In addition to the above, the surface tension of the ink used may be increased. In general ink, a penetrant made of alcohols such as ethanol is added to reduce the surface tension of the ink before use. Therefore, by increasing the surface tension of the ink by increasing the amount of water added to the ink, as shown in FIG.
20 does not spread on the intermediate transfer member 11
1 is attached to the surface and this state is maintained.

Water repellent treatment on the surface of the intermediate transfer body 11 In addition to the above, the surface of the intermediate transfer body 11 may be subjected to a water repellent treatment to improve water repellency. As the water repellent treatment, for example, polydimethylsiloxane or a silicone resin formed by substituting or adding other components to it, such as polytetrafluoroethylene or a fluororesin formed by using other components, is intermediately transferred. This is done by coating the surface of the body 11. With this, as well as
As shown in FIG. 2B, the ink droplets 120 adhere to the surface of the intermediate transfer body 11 without spreading on the intermediate transfer body 11,
This state is maintained.

Next, the operation will be described. While rotating the intermediate transfer member 11 at a predetermined speed in the direction of the arrow in FIG.
By ejecting the ink droplets from the recording head 12, the ink droplets adhere to the surface of the intermediate transfer member 11 to form an ink image. The ink image is attached to the surface of the intermediate transfer body 11 so that adjacent ink droplets are separated from each other.

Then, in synchronism with the formation of the ink image, the recording paper secondarily fed by the registration roller pair 17 is sandwiched between the intermediate transfer body 11 and the pressure roller 21 and conveyed, and the intermediate transfer body is applied by the applied pressure. The ink image on 11 is transferred to the recording paper.

At the time of this transfer, the ink droplets are pressed against the recording paper, and the adjacent ink droplets become continuous. That is, a line formed by a set of dots on the intermediate transfer body 11 is printed as a continuous line on the recording paper.

Then, the recording paper on which the image is transferred is discharged to the discharge tray 20 by the discharge roller pair 19, and the ink remaining on the surface of the intermediate transfer body 11 is removed by the cleaning device 22.

In this way, the intermediate transfer body 1 is so arranged that the ink droplets 120 ejected onto the intermediate transfer body 11 are separated from each other.
Since the ink droplets 120 are attached to the surface 1, it is possible to maintain the separated state of the ink droplets 120 on the intermediate transfer body 11 without coalescing, thereby obtaining a high-quality printed image when transferred to the recording paper. To be

Incidentally, as shown in FIG. 3, the intermediate transfer body 11, the recording head 12 and the cleaning device 22 may be symmetrically arranged on the front and back surfaces of the conveyed paper.

The peripheral surfaces of the intermediate transfer members 11 and 11 are pressed against each other with a required pressure, and the recording paper sandwiched between the intermediate transfer members 11 and 11 is conveyed and conveyed.
The ink image formed on the surface of 11 is transferred to both surfaces thereof by the applied pressure.

As a result, in the form of FIG. 3, it is possible to print on both sides of the recording paper at the same time. Further, the intermediate transfer bodies 11 and 11 can also function as pressure rollers, and there is no need to dispose a pressure roller separately.

FIG. 4 is a front view showing the main part of the second embodiment of the ink jet recording apparatus according to the present invention. FIG.
FIG. 3 is a block diagram showing a configuration of ink droplet ejection control of the same embodiment. The same members as those in the first embodiment are designated by the same reference numerals. In the second embodiment, the intermediate transfer member 11,
On the downstream side of the recording head 12, the pressure roller 21, and the cleaning device 22 in the sheet conveying direction, the intermediate transfer member 1 having the same configuration
1, a recording head 12, a pressure roller 21, and a cleaning device 22 are provided, and print data input from an external device such as a personal computer or an image reading device is printed by a control unit 30 on a recording sheet.

The recording heads 12 are arranged so as to face the intermediate transfer body 11 in a direction in which the longitudinal direction thereof is orthogonal to the sheet conveying direction, whereby the size of the apparatus in the sheet conveying direction is reduced. Hereinafter, for convenience of description, the upstream side in the paper conveyance direction is the intermediate transfer body 11a and the recording head 12a, and the downstream side is the intermediate transfer body 11b and the recording head 12b.

The recording head 12a (12b) includes a piezoelectric element 121a (121b) for pressurizing the pressurizing chamber and a drive circuit 122a for driving each piezoelectric element 121a (121b).
(122b).

The piezoelectric element 121a (121b) is composed of the same number of nozzles as PZT, for example, and is arranged on one side wall of the pressurizing chamber corresponding to each nozzle. A voltage signal is applied to and deforms to pressurize the pressurizing chamber.

The drive circuit 122a (122b) is composed of a power source, a transistor and the like, and applies a voltage signal between the electrodes of each piezoelectric element to deform the piezoelectric element. Also,
The drive circuit 122a (122b) includes the recording head 12a.
(12b) Arranged in a proper place in (12b), having a latch part, for temporarily latching input serial binary or multi-valued print data for one line of paper, converting it to a parallel signal and outputting it. is there.

The control unit 30 includes a CPU 31 and a storage unit 32.
And the like, and controls the ink droplet ejection operation of the recording heads 12a and 12b. The storage unit 32 includes a ROM that stores control programs and fixed data, and a RAM that temporarily stores data and the like.

The CPU 31 outputs the print data to be printed to the drive circuits 122a and 122b of the recording heads 12a and 12b.
To the drive circuits 122a, 12
The parallel signals converted by 2b are applied to the piezoelectric elements 121a, 1a.
21b is output as a pulse drive signal to the corresponding PZT to control the ejection of ink droplets.

At this time, the CPU 31 causes the recording head 12 to
The print data is divided and transmitted to a and 12b. In this division, the print data of one line is thinned out every other corresponding nozzle to the recording head 12a and is transmitted, and the corresponding nozzles of the print data are alternately shifted and transmitted to the recording head 12b. The remaining print data is transmitted. That is, as shown in FIG. 6, the data corresponding to the ink droplet 120a is transmitted to the recording head 12a, and the data corresponding to the ink droplet 120b is transmitted to the recording head 12b, so that the adjacent nozzles are treated. The print data to be transmitted is divided and transmitted to the recording heads 12a and 12b.

As a result, the recording paper is stored in the recording head 1.
The ink image formed on the intermediate transfer body 11a is transferred by 2a, and the intermediate transfer body 11 is further transferred by the recording head 12b.
When the ink image formed on b is transferred, the image is printed.

Further, the CPU 31 changes the voltage level of the pulse drive signal output to each PZT to the intermediate transfer bodies 11a and 1a.
As shown in FIG. 6, the diameter R of the ink droplets 120a and 120b ejected on the 1b is set to a value such that R <√ (2) D.

As a result, the recording heads 12a and 12b
As a result, ink images are formed on the intermediate transfer bodies 11a and 11b so that adjacent ink droplets do not contact each other.

As described above, the recording head 12a facing the intermediate transfer body 11a and the recording head 12b facing the intermediate transfer body 11b are arranged along the sheet conveying direction, and the print data is printed to the recording heads 11a and 11b. By thinning out and transmitting, the ink images on the intermediate transfer bodies 11a and 11b are formed so that adjacent ink droplets do not come into contact with each other, so that the ink droplets 120a and 120b ejected onto the intermediate transfer bodies 11a and 11b are combined. It is possible to maintain the separated state without doing so, and thereby a high-quality printed image can be obtained when transferred to a recording sheet.

As shown in FIG. 7, similarly to the case of FIG. 3, the intermediate transfer body 11a, the recording head 12a, and the cleaning device 22 are arranged symmetrically with respect to the conveyed paper, respectively, and have the same structure. The recording head 12a and the cleaning device 22 are disposed symmetrically to the intermediate transfer member 11b, the recording head 12b and the cleaning device 22, respectively, and the intermediate transfer member 11b and the recording head 12 having the same configuration are provided.
b and the cleaning device 22 may be provided respectively.

The intermediate transfer bodies 11a, 11a and the intermediate transfer bodies 11b, 11b are arranged such that their peripheral surfaces are pressed against each other with a required pressure, and the recording paper is the intermediate transfer bodies 11a, 1b.
Intermediate transfer bodies 11a, 11 while being sandwiched between 1a and being conveyed.
The ink image formed on the surface of a is transferred to both sides by the applied pressure, and further, the ink image formed on the surface of the intermediate transfer bodies 11b and 11b is conveyed while being sandwiched between the intermediate transfer bodies 11b and 11b. It is transferred to both sides by the applied pressure.

As a result, in the form of FIG. 7, it is possible to print on both sides of the recording paper at the same time. In addition, the intermediate transfer bodies 11a and 11a and the intermediate transfer bodies 11b and 11b.
Can also function as pressure rollers, and there is no need to provide a separate pressure roller.

[0048]

As described above, according to the first aspect of the invention, since the ejected ink droplets are attached to the surface of the intermediate transfer body so as to be separated from each other, a plurality of ink droplets are formed on the surface of the intermediate transfer body. Therefore, a high quality printed image can be obtained.

According to the second aspect of the invention, the diameter of the ink droplets adhering to the surface of the intermediate transfer member is set to a value less than the constant pitch of the nozzles formed in the recording head. Since the droplets are separated and attached, a plurality of ink droplets do not coalesce on the surface of the intermediate transfer member, and a high quality printed image can be obtained.

According to the third aspect of the invention, the ink droplets that are adjacent to each other in the direction orthogonal to the transport direction of the recording medium are first
Recording head for ejecting ink droplets toward the intermediate transfer body, and a second recording head for ejecting ink droplets toward the second intermediate transfer body downstream of the first intermediate transfer body in the transport direction. The ink droplets attached to the surfaces of the first intermediate transfer body and the second intermediate transfer body are surely separated from the adjacent ink droplets, respectively. Ink droplets do not coalesce on the surfaces of the first and second intermediate transfer members, and a high quality printed image can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view showing an internal configuration of a first embodiment of an inkjet recording apparatus according to the present invention.

FIG. 2 is a diagram showing ink droplets adhering to the surface of the intermediate transfer member 11, FIG. 2A is a plan view for explaining the size of the ink droplets,
FIG. 6B is a diagram showing a state where the ink droplet is viewed from the side.

FIG. 3 is a front view showing a main part of a modification of the first embodiment.

FIG. 4 is a front view showing a main part of a second embodiment of an inkjet recording apparatus according to the present invention.

FIG. 5 is a block diagram showing a configuration of ink droplet ejection control of the same embodiment.

FIG. 6 is a diagram showing an intermediate transfer member 11a, 11b in the same embodiment.
It is a figure explaining the ink drop discharged above.

FIG. 7 is a front view showing a main part of a modification of the second embodiment.

[Explanation of symbols]

 11, 11a, 11b Intermediate transfer body 12, 12a, 12b Recording head 120, 120a, 120b Ink droplet 121a, 121b Piezoelectric element 122a, 122b Drive circuit 21 Pressure roller 30 Control section 31 CPU

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Koichi Baba 1-2-2 Tamatsukuri, Chuo-ku, Osaka Mita Industrial Co., Ltd. (72) Yoshiko Uryu 1-2-2 Tamatsukuri, Chuo-ku, Osaka Mita Within Kogyo Co., Ltd. (72) Inventor Setsuo Hori 1-22 Tamatsukuri, Chuo-ku, Osaka Mita Kogyo Co., Ltd.

Claims (3)

[Claims] 1. An ink image is formed by ejecting ink droplets from nozzles formed at a constant pitch on a recording head toward the surface of an intermediate transfer member according to print data, adhering to the surface of the intermediate transfer member to form an ink image. In a transfer type inkjet recording apparatus for transferring the ink image to a recording medium to perform printing, an ink image forming means is provided for adhering the ejected ink droplets to the surface of the intermediate transfer body so that they are separated from each other. Transfer type inkjet recording device. 2. The transfer type ink jet recording apparatus according to claim 1, wherein the ink image forming means sets the diameter of the adhered ink droplets to a value less than the constant pitch. 3. The intermediate transfer member comprises a first intermediate transfer member and a second intermediate transfer member downstream of the first intermediate transfer member in the transport direction, and the recording head comprises the first intermediate transfer member. ,
The first and second recording heads eject ink droplets toward a second intermediate transfer member, and the ink image forming means records the ink droplets adjacent to each other in the direction orthogonal to the transport direction. 2. The transfer type ink jet recording apparatus according to claim 1, further comprising a dividing unit that distributes and ejects the head and the second recording head.