JPH11179928A - Ink jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording apparatus having a cap mechanism simple in constitution. SOLUTION: An ink jet printer applies recording on a recording medium on the basis of the emission of ink. In the ink jet printer, the nozzle surface of a recording head 1 emitting ink and a blaket cylinder 2 transferring emitted ink to retransfer the transferred ink to the recording medium are brought to a close contact state at a time of non-use of the ink jet printer by the eccentric cam 10 rotated by a head driving motor, the spring 9 pushing the recording head toward the eccentric cam 10 and the member guiding the movement of the recording head 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ink jet recording apparatus for recording on a recording medium by discharging ink.

[0002]

2. Description of the Related Art An ink jet printer using a piezoelectric element as a recording head has been known. In such a recording head, a pulse voltage corresponding to image data is applied to the piezoelectric element, and the ink in the ink channel serving as a predetermined container is pressurized by the distortion of the piezoelectric element caused by the application of the pulse voltage, and the ink channel The ink drop is ejected from a nozzle hole provided in the recording paper toward a recording sheet such as a paper or an OHP sheet. An image based on image data transmitted from a personal computer or the like is recorded on the recording sheet by ejection of these ink drops.

In the above-described ink jet printer, if left unprinted for a long time, the ink in the portion exposed from the nozzle holes of the recording head dries, and the ink cannot fly due to an increase in viscosity or solidification. In order to prevent this, an ink jet printer is generally provided with a cap mechanism for sealing a nozzle surface (a surface on which a nozzle hole of a recording head is formed) with a cap.

[0004] In a carriage scanning type ink jet printer in which a recording head is generally mounted on a carriage, this cap mechanism is provided in an area outside the printing area where the carriage can move, and the recording head is moved when printing is not performed. The capping is performed by moving to the non-printing area.

[0005]

However, a line type recording head provided in an ink jet printer, in which a plurality of nozzles are formed in a straight line, has been increased in size by providing a large number of nozzles. If a cap mechanism for moving the recording head to the non-printing area is used for the large recording head as described above, the cap mechanism is inevitably increased in size and complexity. There are problems such as an increase in size.

In order to prevent the cap mechanism from becoming large,
A cap mechanism that performs capping by moving a recording head in a vertical direction from a printing surface and sliding a cap in parallel with the printing surface has been devised. However, even with such a cap mechanism, it is necessary to move the recording head, which must be fixed at the printing position with high accuracy at the time of printing, at least several cm in order to insert the cap member, and the recording head and the cap Must be moved in conjunction with each other, which complicates the cap mechanism.

The present invention has been made in view of the above points, and an object of the present invention is to provide an ink jet recording apparatus having a cap mechanism with a simple structure.

[0008]

The first aspect of the present invention is an ink jet recording apparatus that performs recording on a recording medium based on ejection of ink.

The ink jet recording apparatus includes a discharge unit for discharging ink, a transfer unit for transferring the ink discharged by the discharge unit and re-transferring the transferred ink to a recording medium, and a discharge unit when the ink is not discharged. Means for bringing the transfer means and the transfer means into close contact with each other.

According to the first aspect of the present invention, the discharge means for discharging the ink, and the transfer means for transferring the discharged ink and re-transferring the transferred ink to the recording medium,
When the ink jet recording apparatus which does not eject ink is not used, the ink jet recording apparatus is in close contact. Thus, when the ink jet recording apparatus is not used, an increase in the viscosity and solidification of the ink around the ejection unit are prevented, and an ink jet recording apparatus having a simple cap mechanism can be provided.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an ink jet printer according to one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a configuration around a recording head 1 of an ink jet printer according to one embodiment of the present invention.

Recording head 1 of the present ink jet printer
In the periphery, an ink jet recording head 1 for offset-printing an image on a blanket cylinder 2, a blanket cylinder 2 for transferring an offset-recorded image onto a recording medium 3 while being rotated in the direction of arrow A, and being conveyed in the direction of arrow B. A recording medium 3 for transferring the image on the blanket cylinder 2 while storing the recorded image, and an impression cylinder 4 for applying an appropriate printing pressure when transferring the image from the blanket cylinder 2 to the recording medium 3
And a transport roller 5 that transports the recording medium 3 and a cleaning mechanism 6 that removes ink remaining without being transferred.

Here, when recording on the recording medium 3,
The blanket cylinder 2, the impression cylinder 4, and the transport roller 5 are driven in conjunction with a drive motor (not shown) and a gear train, and a recording head other than the moving mechanism of the recording head 1 and the configuration of the blanket cylinder 2. The details of the structure and the like are the same as those well known in offset printing presses and the like which are widely used at present, and a description thereof will be omitted.

The recording head 1 is a line type recording head capable of printing at a resolution of 360 dpi and having 2800 nozzles arranged in one line. Also, here
The recording head 1 uses an electromechanical conversion type in which a piezoelectric element is used as a driving element and ink is ejected from a nozzle by a pressure generated by a change in volume. Recording heads based on other flying principles can also be used.

When the ink jet printer is not used, the nozzle face of the recording head 1 can be brought into close contact with the blanket cylinder 2 by a mechanism described later, whereby the nozzle face is capped and sealed.

As the material of the blanket cylinder 2, nitrile rubber, butyl rubber, ethylene propylene rubber, urethane rubber, or the like is used depending on the type of ink to be used. Paper, OHP sheet, etc., which have been subjected to various surface treatments, are used.

Next, advantages of using the blanket cylinder as in the present ink jet printer will be described.

One of the advantages of using a blanket cylinder is that high-speed printing is possible and appropriate printing is possible regardless of the type of recording medium. That is, a heating mechanism using a heater is provided in the blanket cylinder, and by using this heating mechanism, the ink is ejected from the recording head in a low-viscosity state suitable for flying, and the solvent component of the ink is evaporated on the blanket cylinder, and the ink is discharged. In the state of viscosity, it can be transferred to a recording medium by an appropriate printing pressure. As a result, the drying speed of the ink is increased to enable high-speed printing, and further, by changing the printing pressure with the recording medium according to the type of the recording medium, appropriate printing can be performed regardless of the type of the recording medium. it can.

Further, the blanket cylinder is made of porous rubber (for example, manufactured by kneading an organic foaming agent into rubber and heating to generate air bubbles) without depending on the heating mechanism in the blanket cylinder as described above. Alternatively, the same effect can be obtained by using a porous material such as felt fibers impregnated in an elastomer, providing a suction mechanism inside the blanket cylinder, and sucking the solvent component through the suction mechanism.

One of the other advantages of using a blanket cylinder is that harmful pattern noise can be reduced. In ink jet recording, the flying direction of ink from a nozzle may vary among a plurality of nozzles, and if the flying direction is different, the intervals between recording dots on a recording medium become uneven, which is perceived as noise. I will. In particular, in the case of using a recording head in which nozzles are formed in a line shape, streak-like noise having a fixed pattern is generated in the transport direction of the recording medium, resulting in extremely poor image quality.

Variations in the flight direction can be dramatically improved by shortening the distance between the recording head and the recording medium as much as possible. Is not constant, it is necessary to always provide a certain distance or more. In addition, even when a mechanism for adjusting the distance between the recording medium and the recording head is provided for each type of recording medium, the recording medium that has absorbed ink by printing is deformed by expansion and contraction. The recording head and the recording medium cannot be brought close to each other. Further, when paper is used as a recording medium, a certain distance is set in order to avoid troubles such as fine fiber scraps of paper adhering to the nozzle surface of the recording head and hindering ink flying. There is a need.

On the other hand, in an ink jet printer using a blanket cylinder, there is very little change in the distance between the recording head and the blanket cylinder, and there is no generation of fiber waste. The distance between the recording head and the blanket cylinder can be shortened. This enables high-quality printing with reduced streak noise.

Next, the cap mechanism of the ink jet printer will be described in detail with reference to FIGS.
FIG. 2 is a diagram showing a mechanism around the recording head including a moving mechanism of the recording head 1, and FIG. 3 is a perspective view showing a mechanism around the eccentric cam 10 and the recording head 1 in FIG.

As shown in FIGS. 2 and 3, the ink jet printer has a cap mechanism provided on a guide pin 7 provided at an end of the recording head 1 and a housing 14 for holding the entire printing section. A guide groove 8 for reciprocating the recording head 1 along a guide pin 7;
A spring 9 for pushing the recording head 1 in the direction of 0, an eccentric cam 10 having an eccentric amount which is an amount of movement of the recording head 1,
A head drive motor 11 which is a stepping motor for rotating the eccentric cam 10, a pulley 12 for transmitting rotation of the head drive motor 11 to the eccentric cam 10, and a rubber belt 13 are provided.

Although FIGS. 2 and 3 show only one side of the ink jet printer, the guide pins 7, the guide grooves 8, the springs 9 and the eccentric cams 10 are also provided on the opposite side surface of the ink jet printer. The eccentric cams 10 provided on both sides operate in conjunction with each other through an interlocking shaft 15 so as to keep the nozzle surface of the recording head 1 and the blanket cylinder 2 parallel to each other.

The head drive motor 11 sends a corresponding drive pulse from a motor controller (not shown) to rotate the eccentric cam 10 in the direction of arrow C in FIG. The recording head 1 is moved from the printing position to the cap position as follows.

During the printing operation, the recording head 1 is positioned at an end (printing position) farther from the blanket cylinder 2 so that the guide pin 7 is held by the guide groove 8 and contacts the eccentric cam 10 at the portion D in FIG. It is urged and fixed by the spring 9. Thus, the recording head 1 can perform printing at a position where a certain distance is maintained from the blanket cylinder 2.

In the non-printing operation, the recording head 1 is held by the guide pins 7, the guide grooves 8 and the springs 9 and the eccentric cam 10 is brought into contact with the eccentric cam 10 at the portion E in FIG. , And is moved to a position (cap position) where the entire nozzle surface of the recording head 1 is in close contact with the blanket cylinder 2, and the capping function of the blanket cylinder 2 on the nozzle surface of the recording head 1 is performed.

As described above, in the present ink jet printer, the nozzle surface of the recording head is brought into close contact with the surface of the blanket cylinder during non-printing, thereby eliminating the need for providing a special cap member. And a cap mechanism can be configured very simply.

Further, the moving distance of the recording head required for capping is at most several meters from the surface of the recording head.
m to the surface of the blanket cylinder at a distance of about m,
It is possible to easily configure a recording head moving mechanism capable of ensuring the required positional accuracy during printing.

In the ink jet printer according to the above-described embodiment, the entire blanket cylinder is made of a uniform material. However, a portion performing a cap function and a portion used for printing are specified on the circumference of the blanket cylinder. By designating the positions, each can be made of a different material more suitable.

For example, a portion used for printing is made of the above-mentioned material such as nitrile rubber, butyl rubber, ethylene propylene rubber, urethane rubber or the like having a high affinity for ink, and a portion having a cap function is made of silicon rubber. It can be made of a material that repels ink, such as fluorinated rubber or fluorine rubber, or even with the same material, it can be configured to lower the hardness of the rubber at the cap and increase the adhesion to the recording head. is there. Further, when the blanket cylinder is made of porous rubber as described above, it is necessary to use highly airtight rubber for a portion that functions as a cap.

Further, in the ink jet printer of the above-described embodiment, the recording head is of a line type, but a shuttle type recording head may be used.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration around a recording head 1 of an ink jet printer according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a mechanism around a recording head 1 including a mechanism for moving the recording head.

FIG. 3 is a perspective view showing a mechanism around an eccentric cam 10 and a recording head 1 in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording head 2 Blanket cylinder 3 Recording medium 4 Impression cylinder 5 Conveyance roller 6 Cleaning mechanism 7 Guide pin 8 Guide groove 9 Spring 10 Eccentric cam 11 Head drive motor 12 Pulley 13 Rubber belt 14 Housing 15 Interlocking shaft

Claims (1)

[Claims] 1. An ink jet recording apparatus for performing recording on a recording medium based on discharging ink, comprising: discharging means for discharging ink; and transferring the ink discharged by the discharging means. An ink jet recording apparatus, comprising: a transfer unit for re-transferring ink to a recording medium; and a unit for bringing the ejection unit into close contact with the transfer unit when the ink is not ejected.