JP2002292841A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet printer in which high quality images can be recorded continuously at a high speed by drying ink quickly with hot air. SOLUTION: In the ink jet printer where ink is dried with hot air, the image recording position of an ink jet recording head and the drying position of a drying means are separated by a distance of W×V×α or longer, where W is the maximum ink delivery per unit area W, V is the carrying speed of an image receiving medium, and α is a coefficient being set depending on an objective image receiving medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of an ink jet printer, and more particularly, to an ink jet printer capable of continuously recording high-quality images at high speed.

[0002]

2. Description of the Related Art Thermal ink jets, in which a portion of ink is rapidly vaporized by heating by a heater and ink droplets are ejected from nozzles by the expansion force or the like, are used in various printers (Japanese Patent Laid-Open No. 48-48). No. 9622,
No. 54-51837, etc.). Further, there is also known a printer using an ink jet that vibrates a vibration plate by driving means such as static electricity or a piezo element, and discharges ink droplets from nozzles by using the energy (JP-A-11-207956 and JP-A-11-207956). 309850, etc.).

[0003] As with other various printers, such ink jet printers are required to operate at high speed. Here, in an ink jet printer that records an image by ejecting / landing ink droplets onto an image receiving medium such as an image receiving paper and fixing the image, image recording is performed at high speed.
In order to output prints continuously, it is necessary to consider not only the speed of recording but also the improvement of the drying ability of ink (image receiving medium).

[0004]

For example, when the recording density is 6
In an ink jet printer using an ink jet recording head of 00 dpi and a maximum ink discharge amount of 10 pl / pix, (0.025 / 600) × (0.025 / 60)
0) in an area of about 1.736 × 10 ⁻⁹ m ² ,
0 pl = 1 × 10 ⁻⁸ m ³ ≒ 1 × 10 ⁻⁸ g of ink is applied. Note that one pix (pixel) is the minimum expression unit of an image (the sum of all colors in the case of color). That is, in this case, the maximum ink ejection amount per unit area (1 m ² ) is (1 × 10 ⁻⁸ ) / (1.736 × 10 ⁻⁹ ), and
It is about 6 g / m ² .

[0005] In an ordinary ink jet printer, after image recording (usually the same during recording if it is a line head)
Is about 10 mm / sec, and if the length of the drying section is 300 mm, a drying time of 30 sec can be obtained. On the other hand, if the conveyance speed after image recording is set to 100 mm / sec for the purpose of speeding up, the same drying unit can only take 3 seconds for the drying time.
/ 3 requires a high drying capacity of ² g / (m ² * sec).

Here, various methods have been disclosed as means for drying ink after recording an image in an ink jet printer.
Drying using warm air (hot air) disclosed in Japanese Patent No. 56536 is exemplified. However, the inventors of the present invention have studied that, in an inkjet printer, when high-speed drying such as the above-mentioned 2 g / (m ² * sec) is performed using hot air, the image quality may deteriorate to some extent. I understood that.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and enables high-speed drying of ink by warm air to record high-quality images continuously at high speed (print output). It is an object of the present invention to provide an ink jet printer capable of performing the above.

[0008]

In order to achieve the above object, the present invention provides an ink jet recording head having a plurality of nozzles for discharging ink and ink discharging means corresponding to each nozzle, and an image formed by the ink jet recording head. Drying means for drying the ink of the image receiving medium on which air is recorded using air, and conveying means for conveying the image receiving medium on which an image is recorded by the ink jet recording head to the drying section, and When the maximum ink ejection amount per unit area from the recording head is W, the conveying speed of the image receiving medium by the conveying means is V, and the coefficient set according to the target image receiving medium is α, the ink jet recording head Distance between the image recording position and the drying position by the drying unit by the distance calculated by the formula “W × V × α”. Providing an ink jet printer characterized by Rukoto.

In the ink jet printer of the present invention, when only plain paper and coated paper are to be used as image receiving media, α is set to 0.2 or more, and permeable resin coated paper is used as the image receiving medium. In this case, α is set to 0.4 or more, and when swelling type resin coated paper is used as an image receiving medium, the α is preferably set to 1.2 or more. A nozzle plate in which substantially cylindrical nozzles are two-dimensionally arranged, a two-dimensional slit plate in which slits extending perpendicularly to the transport direction of the image receiving medium are arranged in the transport direction, and transport of the image receiving medium It is preferable to blow air from at least one of the two-dimensional nozzle plates in which nozzles extending perpendicular to the direction are arranged in the transport direction.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an ink jet printer of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

FIG. 1 shows an example of the ink jet printer of the present invention. In FIG. 1, (A) is a front view conceptually showing the configuration of the ink jet printer (a view as seen from the arrangement direction of nozzles described later), and (B).
FIG. 1 is a conceptual diagram of the ink jet printer viewed from an oblique direction.

The ink jet printer 10 (hereinafter referred to as the printer 10) includes an ink jet recording head 50.
As a recording head 50 (hereinafter, referred to as a recording head 50), a so-called line head in which nozzles (recording elements) for discharging ink are arranged so as to exceed the length of at least one side of the corresponding maximum size image receiving paper P is used. . As detailed later,
The printer 10 of the present invention does not cause image quality deterioration due to the ink flow even when high-speed drying is performed with a large amount of warm air, so that the image receiving paper P is continuously conveyed at a high speed to perform high-speed image recording. The line head capable of performing the above is preferably used.

However, the present invention is not limited to a printer using a line head as shown in the figure, but combines the intermittent conveyance of the image receiving paper P (recording medium) with the scanning of the recording head by the carriage to receive the image. While the paper P is stopped,
The image is recorded by scanning the recording head in a direction orthogonal to the arrangement direction of the recording elements, and after one scan, the image receiving paper P is transported by a predetermined length in a direction orthogonal to the transport direction. By repeating the scanning,
A so-called serial type (inkjet) printer that records an image on the entire surface of the image receiving paper P may be used.

A printer 10 shown in FIG. 1 includes a recording unit 12 for recording an image by a recording head 50, and a supply unit 1.
4, preheating section 16, and discharge section 18 (FIG. 1 (B)
Is omitted). The present invention is basically a known inkjet printer except that the recording unit 12 has a feature. Therefore, the printer 10 has
In addition to this, various known members and units installed in various inkjet printers, such as a maintenance unit for cleaning the recording head 50 and a cap for the recording head 50 for preventing drying and clogging of nozzles, may be used. Of course, they may have it.

The supply unit 14 includes a pair of transport rollers 20 and 2
2 and guides 24 and 26. For example, the sheet receiving means (not shown) takes out the image receiving paper P (image receiving medium) taken out of the cassette (storage container for image receiving paper) and sent out to the conveying roller pair 20 in the horizontal direction. From above, and supplied to the preheating unit 16.

The preheating section 16 includes a conveyor 28 including three rollers and an endless belt, and a conveyor 2.
8, a pressure roller 30 pressed against the endless belt from the outside, a housing 16a covering these rollers, and an exhaust fan 34 for exhausting the inside of the housing 16a. Also,
One of the conveyors 28 that presses the image receiving paper P is a heat roller 32. The pre-heating unit 16 holds the image receiving paper P conveyed from the supply unit 14 by the conveyer 28 and the pressure roller 30 while nipping and conveying the image receiving paper P.
Thus, the sheet is heated from the recording surface side via an endless belt, and is conveyed to the recording section 12.

The provision of the preheating section 16 is preferable because heating (preheating) the image receiving paper P before image recording by ink jet can promote drying of the ink that has landed on the image receiving paper P.

In the printer 10 of the present invention, the preheating means is not limited to this.
0 may be a heat roller (heat drum) or, instead of a belt conveyor, the image receiving paper P is nipped and conveyed by a pair of conveyance rollers having one (preferably, a recording surface side) as a heat roller to perform preheating. May go. Further, in the printer 10 of the present invention, in order to prevent curling, a transparent liquid (for example, water) is applied or sprayed on the image receiving paper P prior to the preheating, and the image receiving paper P is conveyed while applying a certain tension (tension). , Preheating (and drying of the applied liquid) may be performed.

The recording section 12 includes a recording head 50, a conveying means 56, and a drying means 58. Also,
Although not shown, the recording head 50 is connected to recording control means for driving each heater of the recording head 50 in accordance with a recorded image, and is further equipped with an ink tank for supplying ink.

As described above, the recording head 50 is a so-called line head in which nozzles for ejecting ink are arranged over a length exceeding one side of the image receiving paper P, and is arranged in a nozzle arrangement direction (hereinafter referred to as a nozzle row direction). To the arrow x in the figure.
It is arranged in the direction (in FIG. 1A, the direction perpendicular to the paper surface). Accordingly, the printer 10 in the illustrated example relatively moves the recording head 50 and the image receiving paper P in a direction orthogonal to the nozzle row direction (hereinafter, referred to as a transport direction),
An image can be recorded on the entire surface of the image receiving paper P.

Such a recording head 50 includes a nozzle for discharging ink droplets, a heater as an ink discharging means disposed corresponding to each nozzle, an ink flow path for supplying ink to each heater (nozzle), and a heater. Is a known ink jet recording head having a driving means (for example, a driving LSI).

Accordingly, in the present invention, the recording head 50
(Printer 10) may be a device that records only a single color ink to record a monochrome image, or
K (black) ink, M (magenta) ink, C (cyan)
A color image may be recorded by ejecting ink such as ink and Y (yellow) ink, or ink such as light C or light M. The recording head 50
May be a so-called top shooter type (face inkjet) or a side shooter type (edge inkjet). In addition, the recording head is not limited to a so-called thermal ink jet that discharges ink by heating with a heater, and a recording head that discharges ink by vibrating a vibration plate of an ink chamber using a piezo element or electrostatic force and the like. There may be.

The conveying means 56 includes rollers 60a and 60b, a suction roller 62, and a porous endless belt 6.
4 and a perforated endless belt 64
Nip roller 68 pressed against roller 60a via
(Omitted in FIG. 1B), and a suction box 70 arranged in the conveyor 66.

The recording head 50 has a nozzle
2 is arranged. In addition, the transport unit 58 continuously transports (scans and transports) the image receiving paper P at a predetermined speed in a transport direction (the direction of the arrow y in the drawing) orthogonal to the nozzle row direction. Therefore, the image receiving paper P supplied from the preheating section 16 is scanned over the entire surface by the recording head 50 (nozzle row), and an image can be recorded on the entire surface of the image receiving paper P by ink ejected from each nozzle. The conveyor 66 is constituted by a perforated endless belt 64, and further has a suction roller 62 and a suction box 70. Therefore, the image can be recorded while the image receiving paper P is stably conveyed while being attracted to the porous endless belt 64, and is kept at an appropriate position with respect to the recording head 50.

According to the conveying means 56, the image receiving surface (the surface from which the ink is ejected) is used until the drying of the ink (image receiving paper P) by the drying means 58 described later is completed (until the paper passes the impression means 58). 2), the image receiving paper P can be conveyed without contacting the member, so that deterioration of image quality or the like due to ink transfer to the member can be prevented, which is preferable. Alternatively, the image receiving paper P is conveyed while being pressed against the conveyor by hot air jetted from the drying means 58, instead of being attracted to the conveyor, so that the image receiving paper P is conveyed in a non-contact manner with the image receiving surface. You may.

In the printer of the present invention, the conveying means of the image receiving paper P after the image recording (and before the end of the drying) is
It is not limited to such non-contact transport means, for example,
The image receiving paper P may be transported by a transport roller pair or the like. Here, in the case of using such a conveying unit that comes into contact with the image receiving surface, it is preferable that the member that comes into contact with the image receiving surface has ink repellency (usually water repellency). The water repellency of the transport means is determined by a method of forming the transport means with a water-repellent material such as Teflon (registered trademark), a method of covering the surface of the transport means with a water-repellent material, or a method of coating the surface with a water-repellent coating or water-repellent plating. What is necessary is just to implement | achieve by a well-known method, such as the method of a water-repellent treatment. Further, it is preferable that the member in contact with the image receiving surface has a small contact area with the image receiving surface. For example, in the case of a roller, it is preferable to use a roller having irregularities on its surface (a roller with a wart).

On a conveyor 66 (porous endless belt 64) between the recording head 50 and the nip roller 68,
That is, the drying unit 58 is disposed downstream of the recording head 50 in the transport direction of the transport unit 56 (hereinafter, simply referred to as downstream). The drying unit 58 ejects warm air (hot air) onto the image receiving surface of the image receiving paper P, on which an image is recorded by the recording head 10 and conveyed by the conveyor 66,
This is for drying the ink that has landed on the image receiving paper P.

Here, in the printer 10 of the present invention,
The maximum ink ejection amount per unit area (1 m ² ) ejected from the recording head 50 is Wmax [g / m ² ], the conveying speed of the image receiving paper P by the conveying means 56 is V [mm / sec], When the coefficient set according to the paper P (image receiving medium) is α, the recording position by the recording head 50 and the drying position by the drying unit 58 (hereinafter simply referred to as the recording head 50 and the drying unit 5).
8) apart from “Wmax × V × α” or more. More specifically, as schematically shown in FIG. 2, an interval L between a landing position of the ink i from the recording head 50 and a drying start position by the drying unit 58 (a position at which the most upstream hot air w is injected). The printer 10 is configured so that [mm] is equal to or more than “Wmax × V × α”.

The printer 10 of the present invention having the above-described configuration can prevent the image quality from deteriorating due to the ink flowing on the image receiving paper P even if the ink is dried with a large amount of warm air. By performing high-speed drying using a large amount of hot air, high-speed and continuous image recording (print output) is realized.

It should be noted that the recording head 50 ejects C, M, Y and K inks to perform color image recording.
When a plurality of nozzle rows are arranged in the transport direction, the interval L is the interval between the printing position (ink landing position) of the most downstream nozzle row and the drying unit 58. Also,
The maximum ink discharge amount Wmax is the maximum ink amount that the recording head 50 discharges per unit area regardless of a color image and a monochrome image. Therefore, for example, if the recording head 50 is to record a full-color image of C, M, Y, and K, the ejection is performed per unit area.
This is the sum of the maximum ejection amounts of all the colors C, M, Y and K.

As described above, an ink jet printer is also required to speed up image recording (print output). Here, in the ink jet recording the image on the image receiving paper P by ejecting ink droplets like an image, the transport speed of the image receiving paper is improved and the drying time is shortened with the increase in speed.
Accordingly, the drying means is required to have a high drying capacity.

Hot air drying can be considered as an ink drying means which can be expected to have a high drying ability. The present invention has conducted various studies on high-speed drying with warm air in order to increase the speed of image recording in an inkjet printer.
It has been found that when the air volume is increased to improve the drying speed, the drying speed can be improved, but the image quality deteriorates with a high probability. Furthermore, as a result of repeated examination of the cause, the ink is sufficiently fixed on the image receiving paper (penetrates).
Earlier, it was found that the ink flowed over the image receiving paper P by applying a strong wind (hereinafter referred to as ink flow), and as a result, the image quality deteriorated.

Here, the fixing time of the ink on the image receiving paper P (=
The ink absorption time) is determined by the ink ejection amount and the ink absorption (water absorption) speed Wa of the image receiving paper P. That is, as shown in the illustrated example, if the printer 10 has a drying unit 58 using hot air downstream of the recording head 50 and performs image recording and drying while conveying the image receiving paper P, the ink absorbing speed of the image receiving paper P Wa [g / (m ² * sec)], maximum ink ejection amount W
From max [g / m ² ] and the transport speed V [mm / sec] of the receiving paper P,
If the recording head 50 and the drying unit 58 are separated from each other by “(Wmax / Wa) × V” or more, ink flow can be prevented.

The ink absorption speed Wa of the image receiving paper P is
The depth of the image receiving paper P is not the spread in the surface direction but the depth (image receiving paper P
Permeation speed in the thickness direction). The permeation of the ink into the image receiving paper P is determined by the ink used and the characteristics of the image receiving paper P, and can be generally expressed by the following Lucas-Washburn equation. I = ((d × t × λ × cos θ) / (4η)) ^1/2 (In the above formula, I; penetration distance, d; capillary diameter, λ;
Surface tension of ink, η: viscosity of ink, θ: contact angle,
t: elapsed time. )

As the image receiving paper P (image receiving medium), plain paper based on paper, coated paper, resin-coated paper (RC
Paper) and media having a film base. here,
In plain paper and coated paper, the base itself also absorbs ink, and thus the properties of the base and the coat layer determine the ink absorbing properties of the entire image receiving paper. On the other hand, in the case of RC paper or a film-based medium, the base does not absorb ink at all, and thus the ink absorbing property is determined by the characteristics of the surface coat layer (image receiving layer).

The ink-absorbing ink in the coating layer is mainly composed of a water-soluble polymer such as gelatin, the main component of which is an image-receiving layer (ink-receiving layer on the surface). Inorganic fine particles, etc., which can be classified into a penetrative type which absorbs ink by a capillary phenomenon generated in a gap between the fine particles. In the swelling type, the surface tends to be sticky after image recording, while in the penetrating type, the ink has a dry feel even after recording since the ink is held in the image receiving layer. In addition, since the swelling type holds the ink by swelling of the image receiving layer, the swelling type has a weight of 30% of the weight of the image receiving layer.
Nearly 0% of the ink can be retained (depending on the state of the film), while the penetration type can retain only an amount of ink corresponding to the thickness of the image receiving layer.

The present inventors have calculated the total amount of absorbed ink 15 seconds after ink ejection for various types of image-receiving paper P for general inkjet printers on the market.
The ink absorption speed Wa was calculated using the Lucas-Washburn equation. As a result, the ink absorption speed Wa of plain paper and coated paper is approximately 1.8 [g / (m ² * sec)], and the ink absorption speed Wa of RC paper having a penetrating ink receiving layer is approximately 0.9 [g]. / (m ² *
sec)], and the ink absorbing speed Wa of the RC paper having the swellable ink receiving layer was about 0.3 [g / (m ² * sec)]. Therefore, utilizing this, the recording head 5
0 and the distance between the drying means 58 and the above-mentioned “(Wmax / Wa) ×
V "or more, it is possible to prevent ink flow caused by the ejection of strong warm air.

Here, in the printer 10, it is not normal that the maximum amount of ink is ejected to a unit area, that is, a solid image having the highest density is recorded. In other words, the image quality does not deteriorate due to the ink flow even if the recording head 50 and the drying unit 58 do not separate from each other normally for “(Wmax / Wa) × V” or more. Therefore, the recording head 5
If the distance between 0 and the drying means 58 is longer than the distance corresponding to the ink absorption speed Wa, the distance becomes substantially longer than necessary, which leads to an increase in the size of the apparatus and a decrease in the recording speed. The printer 10 according to the present invention responds to the recording head 5 by using the coefficient α appropriately set corresponding to the target image receiving paper P.
It has a configuration in which the distance between 0 and the drying means 58 is “Wmax × V × α”.

The coefficient α is determined according to the target image receiving paper P.
Further, for example, the image quality required for the printer 10, the target recording speed (print output speed), the printer 10
The size may be determined as appropriate in consideration of the size of the printer 10, the use of the printer 10, the amount and temperature of the hot air used for drying the ink, and the like. In particular, at the start of drying (the most upstream position of the hot air jet), the amount of ink adhering to the surface of the image receiving paper P is 2 g / g.
m ² ] or less, especially 1 [g / m ² ] or less.
Is preferably determined.

According to the experiments and studies by the present inventors, according to the image receiving paper P to be processed by the printer 10, when only plain paper and coated paper having the highest ink absorption speed Wa are to be processed, α = 0.2 or more, and when permeation type RC paper having a lower ink absorption speed Wa is included as a target, α
= 0.4 or more, and α = 1.2 or more is preferable when swelling type RC paper having the lowest ink absorption speed Wa is included. In consideration of the recording speed and the miniaturization of the printer 10, the coefficient α is preferably small. Thereby, even if the ink is dried with a large amount of warm air, it is possible to preferably prevent the image quality from being deteriorated due to the ink flow. The printer 10 can be realized.

However, for example, even when the printer 10 includes a wet-type RC having the lowest ink absorbing speed Wa as an object of the image receiving paper P, the image quality is required only for plain paper and coated paper. If no image quality is required, α =
Of course, it may be 0.2. Further, the image receiving paper P targeted by the printer 10 of the present invention is not limited to the above-described example.

In the table below, as an example, in image recording by the printer 10, a gelatin-coated swelling type RC paper is used as the image receiving paper P, and “Wma
7 shows the results of a sensory evaluation of image quality deterioration due to ink flow when the recording head 50 and the drying unit 58 are arranged at the interval L calculated by “x × V × α”. In the following table, the evaluation was “good; ○ slightly deteriorated; △ NG;
X ". In this example, the maximum ink ejection amount Wmax of the recording head 50 was 24 [g / m ² ], and the transport speed V of the image receiving paper P was 50 [mm / sec]. The hot air blown by the drying device 58 was at a wind speed of 10 [m / sec] and the temperature was 90 ° C. The spraying was performed by a perforated nozzle described later. The printer 10
Was set at a temperature of 30 ° C. and a humidity of 70%.

[0043] As is clear from the results shown in the above table, when the gelatin-coated swelling type RC paper was used, the coefficient α was 1.2.
By doing so, it is possible to prevent image quality deterioration due to ink flow when ink is dried with warm air.

In the above table, the document print is an image mainly composed of characters and figures (the amount of ink per unit area is small), and the photo print is a photographic image (the amount of ink is large). In the above results, the document print and the photographic print have the same result, although the ink amounts are different. This is because the sharpness of the image is required in a document print mainly composed of characters and figures, and the image quality appears to be greatly degraded even with a small amount of ink flow. It is considered that deterioration is not visually recognized. This result was the same for other types of image receiving paper P.

In the printer 10 of the present invention, various drying means can be used as long as the drying means 58 can spray hot air onto the image receiving paper P (image receiving surface) to dry the ink that has landed on the image receiving paper P. It is possible. In the present invention, the drying unit 58 controls the amount of water contained in the dried image receiving paper P to be 2 or less.
It preferably has a drying ability of not more than [g / m ² ], especially not more than 1 [g / m ² ].

In the illustrated example, the drying means 58 is an injection plate having one surface (bottom surface) formed with a large number of hot air injection ports, and the injection plate faces the conveyor 66 (the porous endless belt 64). A hollow, substantially rectangular parallelepiped casing 80 to be arranged, and a hot air generating means 82 for introducing air into the casing 80 and injecting hot air from an injection port of an injection plate.
And is configured.

In the present invention, the warm air generating means 82 includes:
There is no particular limitation, and for example, a known unit combining various fans and a heating unit that heats the air injected by the fans may be used. As an example, the fan is exemplified by an axial fan, a cross flow fan, a sirocco fan, and the like, and the heating unit is exemplified by a nichrome wire heater, a self-control ceramic heater, and the like. In particular, the combination of a sirocco fan with a high static pressure and the heating means illustrated,
It is suitable. There is no particular limitation on the temperature control means of the hot air in the hot air generation means 82, and the measurement results of the temperature measurement means such as thermistor and thermocouple, the temperature adjustment means such as the heating power adjustment means, and the measurement results by the temperature measurement means A known method having a control means for controlling the temperature adjusting means according to the above may be used.

There is no particular limitation on the temperature, amount and speed of the warm air blown by the drying means 58 onto the image receiving paper P. In addition, in order to realize suitable high-speed drying, the temperature of the warm air is:
90 ° C. or higher, particularly preferably 100 ° C. or higher,
800 [kg / (m ² * hr)] or more in mass velocity, especially 1000 [k
g / (m ² * hr)] or more, and the wind speed is 10 [m / se
c] or more, particularly preferably 12 [m / sec] or more. Further, for the same reason, the drying means 58 (especially, the casing 80) is more than 120 [kcal / (m ² * hr * deg)]
It preferably has a heat transfer coefficient of 40 [kcal / (m ² * hr * deg)] or more.

In the present invention, the printer 10 includes means for measuring the temperature and / or humidity of the installation environment, means for determining the type of the image receiving paper P (further preferably, including the size of the image receiving paper P), It is preferable to have a detecting means (control in accordance with image data is also possible) and the like, and to adjust the temperature of the hot air blown by the drying means 58 or further the amount of air in accordance with the information thus obtained. These adjustments and controls may be performed using, for example, a preset table (look-up table) or an arithmetic expression.

As described above, the bottom surface of the casing 80 is an ejection plate having a number of openings for ejecting warm air to the image receiving paper P. The material for forming the spray plate (casing 80) is not particularly limited, and any material having sufficient heat resistance to the hot air to be sprayed can be used.

Although there is no particular limitation on the configuration of the injection plate, a large number of circular hot air injection holes 84 are two-dimensionally formed, preferably as shown in FIG.
A perforated plate having a staggered lattice shape as shown in (A); a large number of substantially cylindrical hot air jet nozzles 86 having a predetermined height in two dimensions, preferably staggered as shown in FIG. A nozzle plate having a lattice shape; two-dimensional having a plurality of hot air jet slits 88 extending in the nozzle row direction (arrow x direction) in the transport direction (arrow y direction) as shown in FIG. A two-dimensional nozzle plate having a plurality of hot air jet nozzles 90 having a slit-shaped cross section extending in the nozzle row direction and having a predetermined height in the transport direction, as shown in FIG. One or more is preferably exemplified.

In the multi-hole nozzle plate shown in FIG. 3 (B) and the two-dimensional nozzle plate shown in FIG. 3 (D), the inner wall of the hot-air jet nozzle is formed in order to make the hot-air jet smooth. , And preferably has a tapered shape expanding toward the inside of the casing 80.

In particular, the perforated plate shown in FIG. 3A and the nozzle plate shown in FIG. 3B are preferable from the viewpoint of ink drying ability. Here, in such a perforated plate and a nozzle plate, the inner diameter of the (warm air) outlet is D, the pitch of the outlet in the nozzle row direction is P ₁ , the pitch of the outlet in the transport direction is P ₂ , and When the distance between the outlet (perforated plate surface or nozzle tip) and the image receiving paper P is H, “1 [mm]
<D <10 [mm] ”,“ 2D <P ₁ <4D ”,“ 2D <
It is preferable to satisfy one or more, preferably all, of the four conditions of P ₂ <4D ”and“ 4D> H ”. With such a configuration, more excellent ink drying performance can be obtained.

In the drying means 58, a perforated plate or a nozzle plate may be used in combination with a two-dimensional slit plate or a two-dimensional nozzle plate. In this case, a perforated plate or a nozzle plate exhibiting a higher drying ability is disposed upstream, and a two-dimensional slit plate or a two-dimensional nozzle plate having excellent drying (hot air injection) uniformity is disposed downstream. It is preferable to arrange them.

For such a perforated plate or nozzle plate,
This is described in detail in Japanese Patent Application Laid-Open No. 9-133998 by the present applicant.

In the printer 10 of the present invention, it is preferable that the recording head 50 (ink discharge section) and the drying means 58 are spatially separated. With such a configuration, it is possible to prevent drying of the ink ejection portion of the recording head 50 and perform stable high-quality image recording. In order to further improve this effect, the space including the recording head 50 may be pressurized by a method such as introducing air to prevent the flow of warm air (heat) into the space. Good.

The image receiving paper P on which the image is recorded by the recording head 50 by the ink jet while being conveyed in the conveying direction by the conveying means 56 and the ink is dried by the drying means 58 is discharged by the nip roller 68 of the conveying means 56 and the conveyor 66. It is supplied to the unit 18. Discharge unit 18
Transports the image receiving paper P by the transport roller pair 72 and the discharge roller pair 74, and discharges the image receiving paper P to, for example, a discharge tray (not shown).

Here, in the printer 10 of the present invention, the curl (curve) of the image receiving paper P is provided downstream of the drying means 58.
May be arranged. Examples of the decurler include a decal heat roller, a steamer that applies steam to the image receiving paper P, and a tensioner that applies tension to the image receiving paper P. Further, it is preferable that the printer 10 includes a cleaning unit that cleans a member that comes into contact with the image receiving surface downstream of the recording head 50, such as the nip roller 68 and the transport roller pair 72. As the cleaning means, various methods such as a cleaning roller, a cleaning belt, and a water cleaning means such as a shower can be used.

As described above, the ink jet printer of the present invention has been described in detail. However, the present invention is not limited to the above-described embodiment, and may be modified within the scope not departing from the gist of the present invention.
Of course, various improvements and changes may be made.

[0060]

As described above in detail, the ink jet printer of the present invention can be used for recording an image on an image receiving medium by warm air even after drying the ink (image receiving medium) with a large amount of hot air after recording the image by the ink jet. There is no flow of ink that has landed on the surface (ink flow), and there is no deterioration in image quality due to this. Therefore, the ink jet printer of the present invention can perform high-speed ink drying with a large amount of hot air drying, that is, can continuously perform high-speed ink-jet image recording and perform high-speed print output.

[Brief description of the drawings]

FIG. 1 is an example of an inkjet printer using the present invention, in which (A) shows a schematic front view and (B) shows a partial schematic perspective view.

FIG. 2 is a conceptual diagram illustrating a configuration of an ink jet printer of the present invention.

FIGS. 3A, 3B, 3C, and 3D are schematic perspective views of an example of a hot-air jet plate used in the ink jet printer of the present invention.

[Explanation of symbols]

 Reference Signs List 10 (inkjet) printer 12 recording unit 14 supply unit 16 preheat unit 18 discharge unit 20, 22, 72 transport roller pair 24, 26 guide 28, 66 conveyor 30 pressure roller 32 heat roller 34 exhaust fan 50 recording head 56 transport unit 58 drying Means 60a, 60b Roller 62 Suction roller 64 Perforated endless belt 68 Nip roller 70 Suction box 74 Discharge roller pair 80 Casing 82 Hot air generating means 84 Hot air injection holes 86, 90 Hot air injection nozzle 88 Hot air injection slit

Claims (3)

[Claims] 1. An ink jet recording head having a plurality of nozzles for discharging ink and ink discharging means corresponding to each nozzle, and drying the ink on an image receiving medium on which an image has been recorded by the ink jet recording head using wind. Drying means, and conveying means for conveying an image receiving medium on which an image has been recorded by the ink jet recording head to the drying section, and the maximum ink ejection amount per unit area from the ink jet recording head is W, When the conveying speed of the image receiving medium by the conveying unit is V and the coefficient set according to the target image receiving medium is α, the image recording position by the ink jet recording head and the drying position by the drying unit are expressed by the formula “ An ink jet printer which is separated by a distance equal to or longer than a distance calculated by “W × V × α”. 2. When only plain paper and coated paper are to be used as the image receiving medium, the above-mentioned α is 0.2 or more. The ink jet printer according to claim 1, wherein α is 1.2 or more when swelling type resin coated paper is used as an image receiving medium. 3. The drying means includes a perforated plate, a nozzle plate having substantially cylindrical nozzles arranged two-dimensionally, and slits extending in a direction perpendicular to the conveying direction of the image receiving medium arranged in the conveying direction. 3. A wind blown from at least one of a two-dimensional slit plate, and a two-dimensional nozzle plate in which nozzles extending perpendicularly to a transport direction of an image receiving medium are arranged in the transport direction. The ink-jet printer as described.