JPH03213342A - Ink jet recording device - Google Patents

Abstract

PURPOSE:To uniformize temperature distribution of a material to be recorded by a method wherein the adsorbing surface, with which the material to be recorded keeps contact, of a platen having air suction holes for adsorbing the material to be recorded and holding it in a position located facing a recording head is formed of a low thermal conductive material having thermal conductivity lower than a specified value. CONSTITUTION:A plurality of air suction holes 12 are formed in a platen 25 holding a material 6 to be recorded in a position located facing a recording head 1. The material 6 to be recorded is kept in a state to be adsorbed to the platen 25 through suction of air through the air suction holes 12, and ink is discharged from a recording head 1 toward the material 6 to be recorded to effect recording. The absorbing surface, on which the material 6 to be recorded is adsorbed, of the platen 25 is formed of a material having low thermal conductivity the value of which is lower than 1 [W/m.K]. Even when an amount of ink delivered from the recording head toward the material to be recorded is high, this constitution keeps the temp of an adsorbing surface approximately at an equal value, and prevents unevenness in concentration of the air suction hole from occurring to a recording picture.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to an inkjet recording device, and in detail,
The present invention relates to an inkjet recording apparatus equipped with a platen having an air suction port for suctioning and holding a recording material at a position facing a recording head.

[Conventional technology]

Inkjet recording devices are non-impact recording devices with features such as low noise and the ability to easily record color images by using multicolored inks, and have become rapidly popular in recent years. It has become. FIG. 7 shows an example of a conventional ink jet recording apparatus for color recording. Here, reference numeral 1 denotes a color recording head unit, which is constructed by combining recording heads IY, IM, IC, and IB in parallel and is mounted on a carriage 2, which ejects yellow, magenta, cyan, and black color inks. Ink of the color to be used is supplied to each recording head from an ink tank (not shown). 3 and 4 are guide rails for moving the carriage 2;
5 is a platen that holds a recording material 6 at a position facing the recording head unit 1 with a predetermined distance from the ink ejection surface of each head; in this example, the recording material 6 is wound into a roll. and is guided onto the platen 5 by transport rollers 7 and 8.

9 is a feeding roller that feeds the recording material 6 in the f direction;
IO is a motor for driving the feeding roller, and 11 is a pressure roller that is in pressure contact with the conveyance roller rough and driven by the roller 7. Note that sheet feeding is performed in the f direction by an amount corresponding to the recording width each time each ink is ejected onto the recording material 6 and recording is performed by scanning in the P direction by the recording head unit 1. Then, by scanning the recording head unit 1, the next stage of recording is performed in the same manner.

By the way, in such an inkjet recording device,
When recording is performed on the recording material 6 by the recording head unit 1, the distance between each of the recording heads IY to IBk and the recording material 6 is very important. If the recording material 1 comes too close to the ejection surface and comes into contact with it, the recording material 1 will be stained with ink from the recording heads IY to IBk.

Therefore, conventionally, this recording material 6 and the recording heads lY to IB
In order to maintain a constant distance between the recording material 6 and the recording head unit 1, the platen 5 described above is provided to ensure that the recording material 6 is held at a position facing the recording head unit 1. A plurality of air suction holes 12 are provided in the platen 5 in order to prevent it from floating up from the platen 5, and an air suction pump 13 sucks air through the plurality of air suction holes 12 provided in the platen 5. is brought into close contact with the platen 5 to prevent the recording material 6 from lifting off from the platen 5.

However, as described above, the recording material 6 is transferred to the platen 5.
However, the recording material 6 may curl and deform, or the amount of ink ejected from the recording heads lY to IBk may be large, causing the recording material 6 to shrink due to the absorbed ink. If the temperature is too high, the recording material 6 may float up from the platen 5, so the suction force of the air suction pump should be reduced to, for example, -200 m.
It is necessary to make the suction power quite strong, exceeding maq.

In particular, when the recording width of the recording material 6 is wide such as A3 width or A2 width, the width of the platen 5 is similarly wide (this means that the recording material 6 cannot be recorded by the platen 5 over such a wide width). In order to maintain a predetermined distance from the head unit 1, it is necessary to improve the machining accuracy of the recording material holding surface of the platen 5, and it is also important that the platen 5 does not deform due to stress due to temperature changes, etc. Therefore, the platen 5 itself has been made of a metal such as iron or SUS, which has high strength and is difficult to deform.

[Problems to be Solved by the Invention] However, in the conventional inkjet recording apparatus, as described above, the recording material 6 is sucked by the metal platen 5 provided with a large number of air suction holes 12. As shown in FIG. 8, when the amount of recording ink fi14 ejected from the recording heads IY to IB and landing on the recording material 6 increases, the ink 15 that landed on the recording material 6 is The ink is not absorbed uniformly by the material 6, and uneven absorption occurs in a pattern according to the arrangement of the air suction holes 12 on the platen 5. As a result, the recorded image has density unevenness corresponding to the arrangement of the air suction holes 12. This has the drawback of significantly deteriorating image quality.

An object of the present invention is to eliminate the above-mentioned conventional drawbacks, to reliably hold a recording material on a platen, and to produce high-quality recording without uneven density, regardless of the amount of ink recorded on the recording material. An object of the present invention is to provide an inkjet recording device that can obtain a recorded image.

[Means for Solving the Problems] In order to achieve the above object, the present invention has a plurality of air suction holes in a platen that holds a recording material at a position opposite to a recording head, and provides air suction through the air suction holes. In an inkjet recording apparatus that performs recording by keeping the recording material attracted to the platen by suctioning air and ejecting ink from the recording head toward the recording material, at least the recording material on the platen is It is characterized in that the adsorption surface to be adsorbed is formed of a material having a low thermal conductivity, the value of which is 1 [W/m·K] or less.

[For I]

According to the present invention, the recording material has a low thermal conductivity and its value is 1.
Since it is held by the suction part of the platen made of the following materials, the temperature on the suction surface is maintained and defined almost evenly even when a large amount of ink is ejected from the print head toward the recording material. Density unevenness like the air suction holes of the platen does not occur in the recorded image.

〔Example〕

Embodiments of the present invention will be described in detail below based on the drawings, but prior to the description, the cause of density unevenness that was discovered through experiments by the inventor will be described.

In other words, when ink droplets land on a recording material and are absorbed, density unevenness occurs according to the pattern of the air suction holes provided in the platen because the platen abutting part and the air suction part where the recording material stays in contact with each other. This is due to the fact that the ink absorbability differs due to the temperature difference between Looking at the case where the dot lands and is absorbed by this, if the recording material temperature T4 in (Al) is higher than the recording material temperature T in (B), the dot diameter D1 formed on the recording material 6 and D2, the dot diameter D1 where the temperature of the recording material is higher is smaller than the dot diameter D2 where the temperature of the recording material is lower.

In addition, when we actually investigated the temperature on the platen 5 and the recording material 6 with the recording material 6 adsorbed to the platen 5 using the above-mentioned conventional recording device, the results were as shown in FIG. Become. That is, when the platen 5 is suctioned and held by the platen 5, if the platen 5 is made of a metal material with good thermal conductivity as in the past, the recording material abutting portion 5A of the platen 5
and the non-contact part (part related to the air suction hole 12) 5B, the temperature T2 at the non-contact part 5B is as shown in (C).
is higher than the temperature T1 at the contact portion 5A.

Accordingly, the non-recording material 6 also has a temperature distribution corresponding to this as shown in (A), and the temperature T4 of the part corresponding to the non-contacting part 5B is the same as the temperature T4 of the part corresponding to the contacting part 5A, It ends up being more expensive. As a result, it was found that on the non-recording material 6, the dot diameter at the portion corresponding to the non-contacting portion 5B was smaller than the dot diameter at the portion corresponding to the contacting portion 5A, and density unevenness occurred in the image. Ta.

Therefore, in the present invention, the contact portion 5 of the platen 6 is
In order to prevent a temperature difference between A and the non-contact portion 5B, the platen is made of a material that prevents heat from escaping, that is, has low thermal conductivity. Fig. 1 shows the configuration of one embodiment. shows. In the embodiment shown in FIG. 7, at least the suction surface 25A of the platen 25 on which the air suction holes 12 are formed is made of a material with low thermal conductivity, for example, a resin material such as synthetic rubber or plastic. More preferably, the thermal conductivity k [W/a
+-K] (where, W: Watt, m: Meter, K
: Absolute temperature) is preferably 1 or less at room temperature, and polystyrene etc. can be cited as a suitable example. FIG. 2 shows a state in which the recording material 6 is held by the platen 25 configured as described above, and here recording with a width of L is performed by the recording head unit l.
There is almost no difference in temperature between the temperature Tp of the part corresponding to the contact part of the balance 25 and the temperature T of the part corresponding to the non-contact part, and it is possible to obtain a recorded image with uniform density. did it.

FIG. 3 shows a second embodiment of the invention. In this example, a coating layer 25B made of a resin material such as plastic is provided on the recording material holding surface of the metal platen 5. In other words, as mentioned above, the platen needs to have sufficient strength and high surface processing accuracy, and some plastic materials are insufficient in this respect, but this example By doing this, it is possible to select a plastic material from a wide range, and moreover, it is possible to satisfy the above-mentioned conditions and keep the temperature of the recording material holding surface uniform. A suitable example of a coating material for improving the slippage between the recording material 6 and the recording material 6 is a fluororesin (for example, Teflon (trade name)).

FIG. 4 shows yet another embodiment of the invention. In this example, the plastic coating layer 25C is formed of a conductive plastic material (for example, a polymeric material such as polyacetylene, polypyrrole, or polyphenylene vinylene), and the coating layer 25C is electrically grounded.

That is, in order to keep the plastic coating layer provided on the platen 5 in contact with the recording material 6, the plastic coating layer comes into sliding contact with the recording material 6 when the recording material 6 is fed, and the plastic coating layer is damaged by the friction. is charged, and as a result, there is a risk that foreign matter such as paper powder will adhere to the surface of this plastic coating layer, and the adsorption of the recording material 6 will deteriorate. As a result, even if the recording material 6 comes into sliding contact with the conductive plastic layer 25G, it will not be charged by friction. It is possible to prevent foreign matter from adhering.

In the above explanation, the case of a color inkjet recording device has been described, but the application of the present invention is not limited to this.
Needless to say, the present invention can also be applied to a monochrome inkjet recording device.

[Effects of the Invention] As described above, according to the present invention, the platen having air suction holes for attracting the recording material and holding it in a position facing the recording head (which prevents the recording material from coming into contact with the platen) can be used. It is possible to make the composition distribution uniform by using a material with a low thermal conductivity of less than 1 [1.11. First, it is now possible to prevent density unevenness in a pattern corresponding to the air suction holes of the platen from occurring in a recorded image.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of the configuration of the inkjet recording apparatus of the present invention, FIG. 2 is an explanatory diagram of the recording operation according to the embodiment shown in FIG. 1, and FIGS. FIG. 5 is an explanatory diagram showing the change in ink dots caused by the inkjet recording device with the temperature of the recording material. FIG. 6 is an explanatory diagram showing the problems in the conventional inkjet recording device. FIG. 7 is an explanatory diagram of the configuration IP of a conventional inkjet recording apparatus, and FIG. 8 is an explanatory diagram of the problems of the conventional example. 1. Recording head unit; IY, IM, Ic, lBk...recording head, 2
... Carriage, 6... Recording material, 12... Air suction hole, 13... Air suction pump, 14... Ink droplet, 25... Platen, 25A... Adsorption surface, 25B , 25C...plastic coating layer. Figure 4

Claims (1)

[Scope of Claims] 1) A plurality of air suction holes are provided in a platen that holds the recording material at a position facing the recording head, and air is sucked through the air suction holes to move the recording material to the In an inkjet recording apparatus in which recording is performed by discharging ink from the recording head toward the recording material while the recording head is maintained in a state where the recording material is attracted to the platen, at least an attraction surface of the platen to which the recording material is attracted is provided. An inkjet recording device characterized in that it is formed of a material having a low thermal conductivity of 1 [W/m·k] or less. 2) The inkjet recording apparatus according to claim 1, wherein the recording head has a thermal energy generating element as a means for generating thermal energy used to eject the ink.