JPH106491A - Ink jet recorder and head gap holding mechanism used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To convey a printing medium while ensuring a gap distance between an ink jet head and the medium constant even without requiring a high processing accuracy or a high assembling accuracy for a constituting component and to maintain its state for a long period. SOLUTION: A structure that a guide roller 111 is mounted on an ink jet cartridge 101 body or a sheet feeding upstream surface of a head carrier 109 for conveying the cartridge 101 so that the roller 111 feeds on a surface of a printing medium 103 is provided. Further, a blade or a sponge roller for cleaning an outer periphery of the roller 111 is mounted in the cartridge. In addition, in case of feeding the medium, the cartridge is retracted to an outside of the medium.

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 provided with an ink jet cartridge for performing recording by discharging and adhering a recording liquid to a print medium, and a gap holding mechanism between the ink jet cartridge and the print medium used in the apparatus. It is.

[0002]

2. Description of the Related Art Ink jet recording methods include various recording liquid discharge methods, for example, a method of sucking and discharging ink by electrostatic force, a method of applying mechanical vibration or displacement to a recording liquid by using a piezoelectric element, and a method of discharging a recording liquid. In this method, ink droplets are generated and fly, and a part or all of the ink droplets are adhered to a print medium such as paper, for example, in a method of heating and foaming to utilize the pressure, thereby performing recording.

A paper transport mechanism in a conventional ink jet recording apparatus will be described with reference to the drawings. In FIG. 2, the ink jet cartridge 201 is disposed so as to hold a required gap g with the platen 202. Platen 20
Numeral 2 is rotatable with a rubber roller or formed of a resin having good slidability and has a slightly curved convex shape, and has a positional relationship such that the print medium 203 is in contact with the apex of the convex portion of the platen. . The print medium 203 is conveyed to a print area including the inkjet cartridge 201 and the platen 202 by being sandwiched between the capstan 204 and the pinch roller 205. At this time, the capstan 204 is often made of a highly rigid material such as stainless steel, and the pinch roller 205 is often made of an elastic material such as rubber, in order to ensure the accuracy of paper feeding.

The operation of the ink jet recording apparatus will be briefly described. As shown in FIG. 3, the recording apparatus 302 includes a power supply unit 303 for supplying power to each element, and an input image data as required. An image processing circuit 304 that performs data conversion, a controller 305 that controls data exchange between units, and controls an operation sequence, and the like. The external device 30 such as a personal computer is instructed by the controller 305.
1 receives the image data input from the
In step 04, data conversion such as color conversion and edge enhancement is performed, and ink is ejected from the inkjet head unit 306 according to the converted data to form an image on the print medium 307.

In general, an image to be formed is two-dimensional, and the ink discharge ports of the ink-jet head unit 306 are arranged one-dimensionally. Medium 3
07 and an ink jet head conveying means (not shown) for sequentially feeding both in the orthogonal direction and repeating printing. In addition, when printing is performed by moving both, the gap distance between the inkjet head and the print medium must be kept constant. Conventionally, as shown in FIG.
The guide roller 211 is attached to the head carrier 209 with the
The guide roller 211 slides on the guide rail 208 to achieve its purpose. The guide rail 208 is fixed to a frame member (not shown) by screwing or the like.

[0006]

However, in the conventional ink jet recording apparatus having the above structure,
Tolerances within a certain range are required for the parallelism between the sliding surface 212 of the guide rail 208 and the printing surface 213 and the flatness of the sliding surface 212 of the guide rail 208 itself. Assuming that the distance between the sliding surface 212 and the printing surface 213 from the base 211 is a and b, respectively, these are not necessarily constant values, for example, as shown in FIG. Absent. Accordingly, the gap distance g has the same variation as l. Actually, in addition to the above-described shape tolerance of the component alone, an assembly tolerance such as a mounting tolerance of the guide rail 208 is added, and the variation of the gap g becomes a relatively large value, for example, about 0.1 to 0.2 mm. Would. In order to reduce the variation in the gap distance, the processing accuracy and the assembly accuracy of the components such as the guide rail 208 may be increased, but this is not always advantageous because of the cost.

As shown in FIG. 5, when an ink-jet cartridge 501 and a counter electrode 503 are provided and an electric field is applied between them by a DC power supply 502 to cause the charged ink droplet 505 to fly, the ink droplet 505 The acting force is the ink jet cartridge 501 and the counter electrode 5.
03 is proportional to the electric field strength. Therefore, the fluctuation of the gap distance g directly leads to the fluctuation of the force acting on the ink droplet 505, and the image quality is deteriorated due to the fluctuation of the printing condition.

[0008]

Therefore, in the present invention, a guide roller is mounted on an ink jet cartridge or a head carrier for transporting the ink jet cartridge, and the mounting direction is set on the paper feed upstream surface of the ink jet cartridge or the head carrier. The mechanism is such that the guide rollers run on the surface of the print medium instead of running on guide rails as in the prior art. By using such a mechanism, the ink jet cartridge follows the shape of the print medium surface, and if the dimensions are strictly restricted only for the roundness of the guide roller and the eccentricity at the time of installation, the processing accuracy of other components will be reduced. However, the variation in the gap distance can be kept at a considerably small value. In addition, since the guide rollers run on the printing surface on the upstream side of the paper feed, they do not touch the printed ink, so that the printing surface is not stained.

Further, a cleaning means such as a blade or a roller for cleaning the outer peripheral surface of the guide roller is attached to the head carrier or the ink cartridge. By using such a structure, the outer peripheral surface of the guide roller is always cleaned by the scraping action of the blade and the sliding of the roller, so that the gap distance fluctuates with time. There is no. In particular, when a cleaner is attached to the ink cartridge, when the ink cartridge is replaced, the cleaning means such as a blade or a roller is also replaced at the same time, so that a constant gap distance is maintained almost permanently.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an ink jet recording apparatus of the present invention, a guide roller is provided on an ink jet cartridge or a head carrier to maintain a gap distance between an ink jet cartridge and a print medium, and a mechanism for running the print medium surface is provided. The rollers were arranged on the upstream surface in the printing direction. Further, means for cleaning the outer peripheral surface of the gap roller was attached to an ink jet cartridge or a head carrier.

[0011]

【Example】

(Embodiment 1) As an embodiment according to the present invention, when an electric field is applied to a charged ink droplet to cause it to fly (as shown in FIG. 5)
Will be described with reference to the drawings. In FIG. 1, an ink jet cartridge 101 includes a head carrier 109.
When the ink is used up, the cartridge is replaced with a new cartridge, or once the ink is removed, the ink is replenished and the ink is refilled, and then the cartridge is mounted again. The head carrier 109 is guided by a guide shaft 110 so as to be capable of reciprocating in a direction perpendicular to the paper surface and rotating around the guide shaft. This reciprocating movement is performed by the ink jet cartridge 1
This is performed by a pulse motor (not shown) or the like in order to synchronize with the transfer of data to the data transfer unit 01. Also, since the center of gravity of the entire head carrier is on the left side of the guide shaft 110, a moment due to counterclockwise gravity acts on the entire head carrier, so that the guide roller 111 runs while tracing the surface of the print medium 103. Become.

A counter electrode 113 is provided on the back side of the print medium 103.
Is provided, and the inkjet cartridge 101 is provided.
Are formed so as to cover not only the position facing the ink ejection surface, but also the region up to the position facing the guide roller 111.

FIG. 6 is a top view of the printing unit having the structure shown in FIG.
Thus, the print image has already been formed on the right side of the print medium 603 from the head carrier 609. The head carrier 609 is designed such that its home position is point E. The print medium 603 is fed from the pinch roller 605 side, and is conveyed in the C direction. Further, the ink jet cartridge 601 and the head carrier 609 can reciprocate in the A and B directions.

The actual printing operation is performed while the head carrier 609 moves in the direction A at the same time as one or several lines depending on the number of ink ejection ports of the ink jet head 601. At this time, the print medium 603 is in a stopped state. After printing one or several lines,
The head carrier temporarily retreats to the home position E,
In the meantime, the printing medium 603 is sequentially advanced by the number of lines printed in the C direction. After that, the head carrier 609 is returned in the direction B and moved in the direction A, and the next one or several lines are printed. Here, since the rolling direction (A, B direction) of the guide roller 611 is orthogonal to the transport direction (C direction) of the print medium, the head carrier 609 must be retracted to the home position E when the print medium 603 is fed. ,
The conveyance of the print medium 603 is not performed smoothly, and in some cases, the paper feeding accuracy is reduced.

Next, the reason why the gap distance is kept constant will be described. FIG. 7 is a view of FIG. 6 viewed from the pinch roller 605 side. Although the same is described in the conventional example, the shape of the counter electrode 713 is not necessarily a perfect plane but generally has some undulations and inclinations. For example, FIG.
As shown in the figure, the maximum value is undulation of δ, and this value is considered to be about 0.3 to 0.6 mm in comparison with the case where the printing width is 210 mm on the short side of A3. As described in FIG. 1, the head carrier is provided with enough clearance to rotate around the guide shaft,
If the movement in the vertical direction is about 0.3 to 0.6 mm, the head carrier 709 can rotate around the guide shaft 710 and travel along the surface shape of the print medium 703. Since the inkjet cartridge 701 is attached to the head carrier 709, the distance between the ejection surface of the head and the counter electrode 713 is always kept constant for the above-described reason.

In this embodiment, a configuration having one guide roller as the gap holding means for keeping the distance between the ink jet cartridge constituting the ink ejection means and the printing medium constant has been described. Even if it has, the gap holding means can be constituted.

As described above, the gap rollers such as the guide rollers for maintaining the gap run on the surface of the printing medium, so that the outer peripheral surface of the gap rollers becomes dirty with paper dust as the number of prints increases. Is also assumed. In that case, it is effective to provide a cleaning mechanism as shown in FIG. Most of the components are the same as those described above, but as shown in FIG.
The leaf spring 814 and the blade rubbers 815 and 8 are attached to the tip of the arm 812 as shown in FIG.
16 is different in that the structure is attached. When printing is performed while the head carrier 809 moves in the direction A, the guide rollers 811 rotate in the direction C, so that dirt attached to the outer peripheral surface of the guide rollers 811 is scraped off by the blade rubber 815. In addition, when one scan is completed and the blade moves in the direction B to return to the print start position again, cleaning is performed by the blade rubber 816 opposite to the above. In the case of this embodiment, when the ink in the ink jet is used up and a new ink jet cartridge is mounted, the cleaning blade is also replaced at the same time, so that cleaning failure due to wear of the blade rubber is prevented.

FIG. 9 shows another embodiment of the cleaning mechanism.
(A) and (b). What is different from FIG. 8 is that the cleaning roller 914 made of foaming sponge or the like is pressed against the outer peripheral surface of the guide roller 911 to slide and wipe off dirt, instead of scraping with a blade. In particular, it is more effective to make the peripheral speeds of the cleaning roller 914 and the guide roller 911 different from each other so as to slide on the contact surface. Also in this case, since the cleaning roller is replaced at the same time by replacing the ink jet cartridge, the cleaning function is maintained almost permanently.

In this embodiment, the blade rubber or the cleaning roller is used. However, it is needless to say that the present invention is not limited to this system, and that other systems have the same effect. (Embodiment 2) As a second embodiment of the present invention, an example in which a gap holding means is incorporated in an ink jet cartridge will be described with reference to the drawings. As shown in FIG.
The guide roller 1011 is rotatable around a rotation axis 1114. The ink jet cartridge 1001 is detachably attached to the head carrier 1009. When the ink is used up, the ink cartridge is replaced with a new cartridge or the ink cartridge is removed once, refilled with ink, and then attached again. In the case of the structure shown in the present embodiment, the gap distance can be maintained without being influenced by the mounting tolerance between the inkjet cartridge 1001 and the head carrier 1009. Can be.

As shown in FIG. 11, not only the guide rollers 1111 for maintaining the gap but also the guide rollers 1111 are provided.
A cleaning sponge 1115 may be incorporated as a means for cleaning the outer peripheral surface of 11. FIG. 11 (a)
Is an AA cross-sectional view, which has a structure in which dirt such as paper dust is wiped by sliding on the outer peripheral surface of the guide roller 1111.

The operation, the reason why the gap distance is kept constant, and the like have been described in the above-described embodiment, and will not be described. In this embodiment, the cleaning sponge is used. However, it is needless to say that the present invention is not limited to this method, and that other methods such as the method shown in the above-described embodiment can provide the same effect.

[0022]

The present invention is embodied in the form described above and has the following effects. Guide rollers for regulating the gap distance with the print medium are attached to the inkjet cartridge or head carrier, and the surface of the print medium is run. As a result, the gap distance between the ink ejection surface and the printing surface is always kept constant. As a result, the ink ejection state becomes uniform over the entire printing area, and the printed image is stabilized, and unevenness in density, positional deviation, color deviation, and the like hardly occur. This effect is particularly great when the ink droplets are charged and accelerated by electrostatic force.

The guide rollers are located on the upstream side of the paper feed. When the print medium is fed with the paper, the ink jet cartridge or the head carrier with the guide rollers is retracted to the outside of the print medium. The print medium can be transported without adversely affecting the feeding accuracy. Since the guide rollers have a structure that does not touch the ink surface after printing, the risk of soiling the image can be avoided.

Furthermore, since the blade rubber and the sponge roller are integrally formed with the ink cartridge for cleaning the outer peripheral surface of the guide roller, dirt or the like that causes the gap distance to be varied is always removed. . Further, when the ink cartridge is replaced, the above-mentioned cleaning means is also replaced at the same time, and the cleaning performance does not deteriorate.

In addition, if the clearance is made somewhat strict only for the machining accuracy of the gap roller and its mounting,
The desired gap distance can be ensured even if the tolerances in the other components and the assembly are loosened, so that both the component cost and the assembly cost when considering the entire apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment in which a guide roller is provided on a head carrier in an ink jet recording apparatus of the present invention.

FIG. 2 is a side view showing a printing section of a conventional ink jet recording apparatus.

FIG. 3 is a block diagram illustrating an operation of the inkjet recording apparatus.

FIG. 4 is a schematic diagram illustrating a relationship between a distance between a sliding surface and a printing surface of a guide rail from a base and a head position in a main scanning direction.

FIG. 5 is a schematic diagram illustrating an operation when an electric field is applied to a charged ink droplet.

FIG. 6 is a top view illustrating the operation of the ink jet recording apparatus according to the present invention.

FIG. 7 is a schematic diagram illustrating that the gap distance is kept constant in the ink jet recording apparatus according to the present invention.

FIG. 8 is a schematic view showing an embodiment of a cleaning means for a guide roller of the ink jet recording apparatus according to the present invention.

FIG. 9 is a schematic diagram showing another embodiment of a guide roller cleaning means of the ink jet recording apparatus according to the present invention.

FIG. 10 is a side view showing an embodiment in which a guide roller is provided in an ink jet cartridge in the ink jet recording apparatus of the present invention.

FIG. 11 is a side view showing an embodiment in which a guide roller and a cleaning unit are provided in an ink jet cartridge in the ink jet recording apparatus of the present invention.

[Explanation of symbols]

101, 201, 501, 601, 701, 801, 9
01, 1001 Inkjet cartridge 103, 203, 504, 603, 703, 803, 9
03, 1003 Print medium 109, 209, 609, 709, 809, 909, 1
009 Head carrier 111, 211, 611, 711, 811, 911, 1
011 Guide rollers 113 503, 613, 713, 813, 913, 1
013 Counter electrode 815, 816 Blade rubber 914 Cleaning roller 1115 Cleaning sponge

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Kawaguchi 1-8-8 Nakase, Mihama-ku, Chiba-shi, Chiba Prefecture Inside Seiko Electronic Industry Co., Ltd. (72) Satoshi Ohama 1-8-1, Nakase, Mihama-ku, Chiba-shi, Chiba Inside Seiko Electronic Industries Co., Ltd. (72) Inventor Seiji Kuwahara 1-8-1, Nakase, Mihama-ku, Chiba City, Chiba Prefecture Inside Seiko Electronic Industries Co., Ltd. (72) Hiroshi Okano 1-8-1, Nakase, Mihama-ku, Chiba City, Chiba Prefecture Seiko Electronics Industry Co., Ltd.

Claims (8)

[Claims] 1. An ink discharge unit for discharging a recording liquid onto a print medium in accordance with input image data to record an image, and a gap holding unit for keeping a constant distance between the print medium and the ink discharge unit. An ink jet recording apparatus, comprising: a paper feeding means for the printing medium; and a head transport means for transporting the ink discharging means in a direction substantially orthogonal to a paper feeding direction of the printing medium. 2. An ink jet recording apparatus according to claim 1, wherein said gap holding means has one or a plurality of roller members and is attached to a paper feed upstream surface of said ink discharging means or said head conveying means. apparatus. 3. The ink jet recording apparatus according to claim 2, wherein said roller member of said gap holding means runs on a print surface of said print medium. 4. The ink jet recording apparatus according to claim 2, wherein said roller member is attached to said ink discharge means. 5. The ink jet recording apparatus according to claim 2, wherein said roller member is attached to said head transport means. 6. An ink jet recording apparatus according to claim 2, wherein said gap holding means has a cleaning means for cleaning an outer peripheral surface of said roller member. 7. The ink jet recording apparatus according to claim 1, wherein the head transport unit retracts the ink ejection unit outside the print medium when feeding the print medium. 8. An ink discharge means for discharging a recording liquid onto a print medium in accordance with input image data to print an image, a paper feed means for the print medium, and a paper feed direction for the print medium. A head conveying means for conveying the ink discharging means in a direction orthogonal to the ink jet recording apparatus, wherein the gap holding mechanism is rotatably attached to the ink discharging means or the head conveying means via a rotating shaft. A gap holding mechanism, wherein a roller member is configured to be rotatable and movable on the print medium, and keeps a constant distance between the print medium and the ink ejection unit.