JP2002337344A - Printer and printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a printer and a printing method which can improve the printing efficiency remarkably. SOLUTION: In the printer and the printing method, a printing operation is carried out by flying ink supplied to a recording head as liquid drops while adding a quantity of heat according to image information, and adhering the liquid drops to a printing medium opposite to the recording head. A boiling point of a main component of the ink is set to a 150[ deg.C] or lower liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus and a printing method, and is suitably applied to, for example, an ink jet type color printer.

[0002]

2. Description of the Related Art In recent years, with the progress of colorization of image recording of video cameras, televisions, computer graphics, and the like, the demand for colorization of hard copies has been rapidly increasing. In response to this, color printers of various recording systems have been developed and are being developed in various fields.

Among these recording methods, methods for easily outputting a high-quality image with a simple apparatus are broadly classified into a dye diffusion heat transfer method such as a sublimation heat transfer method and a melt heat transfer method, and an ink jet method. .

In the dye diffusion thermal transfer system, an ink sheet coated with an ink layer in which a high concentration of a transfer dye is dispersed in a binder resin, and a print coated with a dyeing resin for receiving the transferred dye are used. In a state where the thermal recording head is pressed against the platen via a transfer object such as paper,
By causing the heat-sensitive recording head to generate heat with an amount of heat corresponding to the image information, the transfer dye of the ink sheet is thermally transferred to the dyeing resin of the transfer target.

By repeating such a series of thermal transfer operations for image signals separated into three subtractive primary colors (yellow, magenta, and cyan), a full-color image having continuous gradation is obtained. ,
The so-called thermal transfer system has attracted attention as an excellent technology for easily miniaturizing and maintaining, having immediacy, and obtaining high-quality images equivalent to silver halide color photographs. In recent years, the thermal method has been widely spread, particularly because the thermal method can easily output a color image as described above.

However, this thermal transfer method is a major drawback in that a large amount of waste is generated due to disposal of the used ink sheet and high running cost is a major drawback.

[0007] On the other hand, the ink-jet method is a method in which small droplets of a recording liquid are formed by a method such as an electrostatic suction method, a continuous vibration generation method (piezo method), or a thermal method (bubble jet (registered trademark) method) according to image information. The recording is performed by causing the nozzles to fly from a nozzle provided in the recording head and adhere to the recording medium.

In such an ink-jet method, although there is almost no waste as in the case of using an ink sheet or the like, since the size of the droplet is determined by the size of the opening at the nozzle tip, the density gradation in the pixel is low. Difficult in principle,
The expression of light and shade depends on the area gradation (the size of the transfer area). As a result, it is very difficult to reproduce a high-quality image comparable to a silver halide photograph obtained by a dye diffusion thermal transfer method due to a reduction in image resolution.

In order to solve such a problem, two methods have recently been adopted. First, as a first method,
This is a method of preparing two types of inks of different densities for the same color to expand the gradation reproduction range. The second method is to reduce the droplet size so as not to give a grainy feeling to human eyes. It is a way to make it.

In the first method, it is necessary to prepare two recording heads for the same color, so that the cost, size, and the like increase in proportion thereto, and there is a problem that the configuration of the entire apparatus becomes complicated.

In the second method, if the droplet size of the droplets adhering to the recording paper is reduced by reducing the droplet size, the graininess is certainly reduced. There is a disadvantage that the resolution of the recording head (that is, the number of nozzles per unit length) must be increased according to the diameter.

For example, in the case of a dot diameter of about 10 [μm], which is said to have no graininess to human eyes, 2000 [d
pi] or higher. Producing a recording head with such a resolution involves difficulties in wiring and mounting, resulting in high costs. Also, preparing an image with a data amount of 2000 [dpi] or more requires an enormous memory, increases the cost, and requires time for data conversion, so that the printing time has to be long.

Therefore, a printer such as a full-color printer has a resolution and gradation that are equal to or higher than those of silver halide photography, can suppress generation of waste after printing, can be transferred to plain paper, and have low running There is a long-felt need for a system that is cost-effective, compact and lightweight, and has immediacy.

[0014]

Recently, a printer which solves such a problem has been proposed (Japanese Patent Laid-Open No. 8-169171).
issue). That is, a porous structure (for example, a large number of fine columnar bodies) is formed in a recording liquid flying section (for example, a recording liquid heating section) of the recording head, and the recording liquid is supplied to the recording liquid flying section, and then heated. This is a recording method in which the state of the recording liquid is changed to generate droplets, and the droplets are transferred to a recording medium facing the recording head.

According to this recording method, the surface area of the recording liquid flying portion can be increased by the amount of the porous structure provided in the recording liquid flying portion of the recording head. Keep by capillary action. In this state, by selectively applying a heat amount corresponding to the recording information to the recording liquid flying portion, a part of the recording liquid is boiled to cause a pressure rise, and a minute amount of the recording liquid corresponding to the image information is minutely generated. Droplets can be transferred to a recording medium.

In the case of this recording method, a large number of droplets (microdots) having a size much smaller than that of a conventional ink jet type nozzle are formed by utilizing the fine holes of the porous structure described above. And the number of generated droplets (that is, the amount of flying droplets) can be freely controlled in accordance with the applied energy (heating energy or the like) according to the recording information to the recording liquid flying portion. Thus, a multi-value density gradation can be obtained, and a recording method (for example, a full-color image) having an image quality equal to or higher than that of a silver halide image can be obtained.

Further, in this recording method, although the droplet size is very small, it is scattered at a resolution of about 300 to 600 [dpi], so that the resolution of the recording head is increased according to the droplet diameter. There is no need to go. In other words, this recording method uses a recording head having a unique structure capable of transferring very fine recording droplets on demand, and at least 128 gradations or more in one pixel per color. An ink jet system capable of gradation expression is realized.

However, according to this recording method, the size of the droplet flying from the recording liquid flying section is small and its initial velocity is also small at 10 [m / s] or less, so that the distance between the recording head and the recording medium is 500. [Μm] or less. For this reason, as a recording medium, a high degree of smoothness is required to avoid contact with the recording head, so that the recording medium is practically limited to dedicated paper, and it is very difficult to record on so-called plain paper. .

The present invention has been made in view of the above points, and an object of the present invention is to propose a printing apparatus and a printing method capable of significantly improving printing efficiency.

[0020]

According to the present invention, in order to solve the above-mentioned problems, the ink supplied to the recording head is caused to fly as droplets by applying heat in accordance with image information, and the droplets are applied to the recording head. In a printing apparatus that performs a printing operation so as to adhere to an opposite printing medium, the boiling point of the main component of the ink is set to a liquid of 150 ° C. or lower.

As a result, in this printing apparatus, the flight distance can be increased by an amount corresponding to the coefficient of thermal expansion of the ink being higher than that of the conventional ink, and plain paper can be used as a printing medium in addition to special paper. It is possible to further increase versatility.

In the present invention, the ink supplied to the recording head is jetted as droplets by applying heat in accordance with the image information, and the droplets are attached to a printing medium facing the recording head. In a printing apparatus that performs an operation, a discharge unit that is provided on a recording head and has a column group having a porous structure for holding supplied ink, and that applies heat to the column group according to image information. And a cover member of a predetermined shape formed on the discharge means and covering the ink flow path and having an opening corresponding to the column group.

As a result, in the printing apparatus, it is possible to prevent dust and the like from entering from outside and adhering to the discharge means by the provision of the lid material, and to dry the ink in the discharge means. Can be prevented from occurring.

Further, in the present invention, the ink supplied to the recording head is caused to fly as droplets by applying a heat amount according to the image information, and the droplets are attached to a printing medium facing the recording head. In a printing apparatus that performs an operation, a discharge unit that is provided on a recording head and has a column group having a porous structure for holding supplied ink, and that heats the column group with a heat amount corresponding to image information When,
A wall member formed around the column group of the ejection unit and having a slit for generating a meniscus of ink is provided at the tip of the column group.

As a result, in this printing apparatus, the meniscus can be generated in the ink itself in the column group by the slit, and the ink can be more easily immersed in the column group by the surface tension, and thus the ink can be discharged from the ejection unit. It is possible to discharge a stable amount of ink droplets.

Further, according to the present invention, the ink supplied to the recording head is caused to fly as droplets by applying heat in accordance with image information, and the droplets are attached to a printing medium facing the recording head. In the printing method for performing the operation, the boiling point of the main component of the ink was set to a liquid of 150 ° C. or lower.

As a result, in this printing method, the flying distance can be increased by an amount that the thermal expansion coefficient of the ink is higher than that of the conventional ink, and plain paper can be used as a printing medium in addition to special paper. It is possible to further increase versatility.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

(1) Configuration of Printer According to the Present Embodiment In FIG. 1, reference numeral 1 denotes an ink jet type color printer as a whole according to the present embodiment, and a plurality of paper feed trays 3 provided on a gantry 2 are provided. Of photographic paper (for example, plain paper) PM, and these photographic paper PM
The sheet is conveyed on the conveying path in the direction indicated by the arrow a one by one and can be supplied to the image printing section 4.

In the image printing section 4, guide plates 5A and 5B are fixed to the gantry 2 on both sides of the transport path so as to sandwich the transport path. Between the image printing unit 4 and the guide trays 5A and 5B between the paper feed tray 3, a rotation shaft 7 having a fan-shaped cross-section taking-in roller 6 fixedly held at the center is rotatably supported. By rotating the rotating shaft 7 in accordance with the driving of the
The photographic paper PM stored in the paper feed tray 3 can be sequentially sent out one by one onto the transport path every time the take-in roller 6 that rotates integrally with the paper feeder 1 makes one rotation.

In the image printing section 4, a pair of conveying rollers 9A and 9B are rotatably supported between guide plates 5A and 5B about a rotation axis at a front stage and a rear stage on the conveying path, respectively. In response to the driving of the drive roller 8, the take-in roller 6 can be rotated in the same direction in conjunction with the rotation of the take-in roller 6.

In the image printing section 4, a platen belt 10 made of, for example, silicone rubber is rotatably provided in a conveying direction (direction of arrow a) or in a direction opposite to the conveying direction below the conveying path in which the printing paper PM is conveyed. Is provided.

The platen belt 10 has a pair of driving rollers 11A, 11 rotatably provided at front and rear positions of a conveying path.
B and three pressure rollers 12A to 12C rotatably supported between the drive rollers 11A and 11B, and the drive roller 6 that rotates according to the drive of the drive mechanism unit 8. The pressure rollers 12A to 12C can rotate in the transport direction or in the opposite direction while rotating in the same direction in conjunction with the rotation.

The driving rollers 11A and 11B and the pressure rollers 12A to 12C are rotatably supported between the guide plates 5A and 5B so as to be positioned at predetermined intervals while maintaining a parallel interval.

The image printing section 4 has three printer heads 13A to 13C each having a substantially line shape, and pressurizing rollers 12A to 12C in a platen belt 10 respectively.
Tank holding portions 15A to 15C are provided at one end side, and ink tanks 14A to 14C are detachably stored and held.

The ink tanks 14A to 14C are filled with inks of three colors, yellow, magenta and cyan, and are stored and held in the corresponding tank holding sections 15A to 15C, respectively. ), Depending on the control
The ink is supplied to the printer heads 13A to 13C via the flow paths formed in the tank holding sections 15A to 15C.

In the image printing section 4, a radiation fin 16 of a predetermined shape made of, for example, aluminum is provided above the printer heads 13A to 13C.
It is attached so as to cover 3A to 13C.

The gantry 2 on one side of the paper feed tray 3
Above, a storage unit 17 that stores a control unit (not shown) that controls a series of operations of the color printer 1 and a power supply unit (not shown) that supplies a required amount of driving power to various circuits.
Is provided. Each printer head 1 of the image printing unit 4
3A to 13C are connected to a control unit and a power supply unit in the storage unit 17 via a flexible board 18.

(2) Configuration of Printer Head Next, as shown in FIG.
Is a rectangular parallelepiped head base 2 made of aluminum material
A long plate-shaped heater chip 21 and a printed board 22 are fixed in parallel to each other on the upper surface thereof, and an ink made of an aluminum material covers the heater chip 21. A channel plate 23 is attached.

At one end of the head base 20, an ink introduction hole 20 for introducing ink supplied from the ink tanks 14A to 14C into the print heads 13A to 13C.
H is formed to penetrate and is electrically connected to the ink tanks 14A to 14C.

The heater chip 21 is, as shown in FIG.
Discharge unit 21 having a plurality of heater functions on a silicon substrate
A ₁ ~21A _N are sequentially formed at predetermined intervals along the longitudinal direction, the respective ejection portions _21A 1 _{~21A N} is conductively connected with the housing part via a flexible substrate 18 (FIG. 1) the power supply unit in the 17 ing.

The plurality of discharge units 21A _{1 to} 21A
_N is provided in a total of 1216 at a pitch of 84 [μm], and one ejection section transfers one dot to obtain a resolution of 300 [dpi].

[0043] printed circuit board 22 is sequentially implemented at predetermined intervals driver IC22A ₁ ~22A _K for a plurality of heating drive along the longitudinal direction, the discharge portion _21A of the heater chip 21, respectively 1 ～21A _It is electrically connected to the _N electrode pattern.

The ink flow path plate 23 has an ink flow path IF (FIG. 3) having a predetermined pattern formed therein.
The ink that flows from the ink through hole 20H of 0 have been made to deliver the respective ejection portions _21A 1 _{~21A N} heater chip 21.

[0045] Specifically, each of the ejection portions _21A 1 _{~21A N} formed at an edge portion of the heater chip 21, as shown in FIG. 4, through the silicon oxide film 31 on the silicon substrate 30, the heating element A polysilicon film 32 divided into a high resistance part 32A and a low resistance part 32B for connection between electrodes is laminated.

On the polysilicon film 32, a silicon oxide film 33 is laminated so as to cover the polysilicon film 32, and openings 33H are formed at positions corresponding to the respective low resistance portions 32B.

In each of the low resistance portions 32B of the polysilicon film 32, a barrier metal layer 34 made of a high melting point metal (for example, titanium or chromium) is formed by lamination through each opening 33H of the silicon oxide film 33. The barrier metal layer 3
An individual electrode 35 or a common electrode 36 is formed so as to cover 4. Then, the high resistance portion 32A of the polysilicon film 32
And a silicon oxide film 37 having a predetermined shape is formed so as to cover the individual electrodes 35 and the common electrode 36.

The silicon oxide film 37 is shown in FIG.
As shown in FIG.₁~ 21A _NIn the porous structure
The column group 37G forming the structure and the column group 37G
The ink supply path IF surrounds in a concave shape and forms a pair.
Shape integrally formed with the partition wall portion 37W for defining the
Having. The cross-sectional view taken along the line AA 'in FIG.
FIG.

In the column group 37G, square columns (or cylindrical columns or the like) 37G _X (X is a natural number) of 13 columns and 13 columns are planted in parallel at predetermined intervals, and among them, the central columns and columns are arranged. Three pillars are planted at positions corresponding to the high resistance portions 32A of the polysilicon film 32. In this embodiment, each of the columnar bodies 37G _X has a diameter of 5 μm.
m], the interval is 5 μm, and the height is 6 μm.

The partition 37W has substantially the same height as the column group 37G, and supplies the ink flowing through the ink flow path plate 23 to the corresponding column group 37G via the ink inflow path IF. It is made to be able to do. Further, an auxiliary wall portion 37WA having substantially the same height as the partition wall portion 37W is formed extending between the pair of partition walls 37W along the ink inflow path IF.

[0051] Thus the respective ejection portions _21A 1 _{~21A N,} upon supplying ink to columnar body group 37G through the ink inflow channel IF by the pair of partition wall portions 37W, by capillary action in the columnar body group 37G Ink can always be held.

In this state, the ink in the column group 37G is selectively applied to the ink in the columnar body group 37G by the heater chip 21 so that a part of the ink is boiled and the pressure rises. Is made to be able to fly.

At this time, the surface tension of the ink in the columnar body group 37G decreases as the temperature rises due to heating. However, it is possible to prevent the ink from escaping from the vicinity of the heating position due to the capillary action by the columnar body group 37G. As a result, necessary ink can be continuously ejected at the time of image transfer.

Each of the printer heads 13A to 13A of the image printing section 4
13C is positioned in advance a predetermined recording start position as shown in FIG. 6, the printing paper when the PM is conveyed onto the platen belt 10, the discharge portions 21A ₁ ~21A _N formed in each of the head chips 21 And the photographic paper PM is 1.0
[Mm].

In addition to the above configuration, in each of the printer heads 13A to 13C of the image printing section 4, a lid (hereinafter referred to as a cover) having a predetermined shape is provided so as to substantially cover the upper portion of the heater chip 21 (that is, the surface facing the printing paper PM). , This is referred to as a shielding lid) 40.

The shield lid 40 is connected to the heater chip 2
Has a plurality of wall portions 40W corresponding to the pair of partition wall portions 37W of the respective ejection portions _21A 1 _{~21A N} formed in 1, so as to prolong the respective wall portions 40W upward, the partition wall 37W
The slits are formed at positions slightly higher than the height of the columnar body group 37G located therebetween.

The shield cover 40 has a plurality of wall portions 4.
In some of the walls 40W, the eaves 40M having a predetermined shape are formed to extend in the right-angle direction on some of the walls 40W so that the ink in the column group 37G can be sufficiently discharged to the outside.

Thus, each of the printer heads 13A to 13C
In each case, dust and the like are mixed from the outside between the eaves portion 40M and the wall portion 40W due to the attachment of the shield lid 40 on the upper portion of the heater chip 21, and the discharge portions 21A ₁ to 2
With the attachment of the 1A _N can be prevented, the ink in the in each discharge portion 21A ₁ ~21A _N can be prevented from being dried.

[0059] Furthermore ink passage the ink has flowed through the IF in the respective ejection portions _21A 1 _{~21A N} is columnar body group 3
By generating a meniscus by the slit formed between the wall portions 40W in 7G, it is possible to make the meniscus more easily immersed in the columnar group 37G by the surface tension.

(3) Ink ejection operation by the image printing unit 4 In the image printing unit 4 described above, three printer heads 13A to 13A (for three colors of yellow, magenta, and cyan) are actually used.
In the head chip 21 provided in the 3C, the ink supplied from the corresponding ink tanks 14A to 14C is boiled by heating with the amount of heat corresponding to the image information to generate bubbles. by flying formed fine droplets from a plurality of discharge portions 21A ₁ ~21A _N formed in each of the head chips 21, is ejected to the paper PM conveyed the droplets on the platen belt 10 Have been made to gain.

In the image printing section 4, tank holding sections 15A-1 corresponding to the respective printer heads 13A-13C.
The ink tanks 14A to 14C are detachably stored in 5C, and each of the ink tanks 14A to 14C has
The following three types of inks are filled for each of the yellow, magenta, and cyan color components.

Specifically, these three types of inks have compositions as shown in FIG. First, in the first ink, Acid Blue 9 (Acid Blue 9) is 3% by weight,
Water (H ₂ O) is 80% by weight, ethylene glycol is 10% by weight, and N-methylpyrroline is 7% by weight.
% By weight, and sodium dodecylbenzenesulfonate is 0.03% by weight.

In the second ink, Disperso Red was 4% by weight, and toluene was 4% by weight.
86% by weight, and dibutyl sebacic acid is 10% by weight. Further, in the third ink, acid yellow (Acid Yellow) is 23% by weight and ethanol is 7% by weight.
7% by weight, and 20% by weight ethylene glycol.

Here, as shown in FIG. 8, the boiling point of water (H ₂ O), which is the main component of the first ink, is 100 ° C.
The boiling point of toluene, which is the main component of the second ink, is 110
[° C], and the boiling point of ethanol, which is the main component of the third ink, is 78 ° C. Incidentally, the boiling point of methyl ethyl ketone is 80 [° C.].

In the first to third inks, it is necessary to add coloring materials for three colors of yellow, magenta, and cyan. A pigment containing an appropriate dispersant is added as a coloring material at a predetermined ratio. Actually, the content of the coloring material in the whole is usually 2 to 100 parts by weight to 1 part by weight of the coloring material (dye or pigment), but is preferably 3 to 30 parts by weight.
~ 20 parts by weight is even better.

Actually, the image printing section 4 controls the plurality of ejection sections 21A _{1 to} 21 formed on each heater chip 21 for each of the printer heads 13A to 13C under the control of the control section.
The A _N are adapted to drive at a predetermined drive conditions according to the type of ink.

[0067] As items of driving conditions in this case, the number per second on-off of the pulse voltage applied to each discharge portion 21A ₁ ~21A _N (hereinafter, this is referred to as ejection frequency) of one gradation pulse time width (Hereinafter referred to as a pulse width), the time required to form one pixel for 64 gradations (hereinafter referred to as a printing cycle), and the ratio of the pulse width to the printing cycle (hereinafter referred to as the Duty ratio).

First, for the first ink, as shown in FIG. 9, the ejection frequency is 50 kHz, and the pulse width is 6 μm.
s), print cycle 1.28 (ms), duty ratio 30
%, The pulse power is set to 100 mW
Drive conditions.

For the second ink, as shown in FIG. 9, the ejection frequency is 100 kHz, and the pulse width is 3 μm.
s), printing cycle 0.64 ms, and duty ratio 15
[%], The pulse power is set to 90 [mW], and this is set as the second drive condition.

Further, as shown in FIG. 9, the ejection frequency of the third ink is 100 kHz and the pulse width is 3 μm.
s), printing cycle 0.64 ms, and duty ratio 15
[%], The pulse power is set to 80 [mW], and this is set as the third drive condition.

As a result, when driven under the first driving condition, as shown in FIG. 10, each of the ejection sections 21A _{1 to} 21A _N
Has an average droplet diameter of 6.6 [μ
m), the flight distance is 3.8 mm, and the dot size is 110 μ
m] to land on the photographic paper PM.

When driving under the second driving condition, FIG.
As shown in 0, the second ink discharged from the discharge portion 21A ₁ ~21A _N has an average droplet size of 7.2 [μm], the flying distance of 4.2 (mm) and the dot size is 115 [μm] Lands on photographic paper PM.

When driving is further performed under the third driving condition, FIG.
As shown in FIG. ₁~ 21A_NSpitting
The discharged third ink has an average droplet diameter of 6.8 [μm],
Marked with a sho distance of 4.2 [mm] and a dot size of 105 [μm]
Lands on the drawing paper PM.

[0074] According to the actual experimental results, these will first to third ink, when driving each discharge portions _21A 1 _{~21A N} in the corresponding first to third driving conditions, the pulse width is 10 [μs In the following, each of the discharge units 21A _{1 to} 21A _N
Did not occur. The discharge distance is 1
(Mm) for a which was below the discharge unit 21A ₁ to 2 formed on each heater chip of a printhead in accordance with the this
1A _N and photographic paper PM: was the distance between (ink jet exclusive paper Konica QP paper (TM)) and 100 [μm].

Further, 64 gradation pulses are generated (ie, 64 gradations).
Since the print density could not reach 2.0 due to the small droplet size and low ejection efficiency, the grayscale pulse was set to 256 shots (256 tones) to reach the print density of 2.0 .

[0076] In this way it is possible to achieve much greater than the distance the flying distance 1 (mm) of the ink ejected from the respective ejection portions 21A ₁ ~21A _N, this result, the printer head and the printing paper PM The distance between them can be increased to about 1 [mm], so that even if the printing paper PM is plain paper, it can be sufficiently applied.

Further, since the diameter of the ink droplet to be ejected is relatively large, the ejection efficiency, that is, the ejection amount per unit input energy is large, and as a result, the driving can be performed with relatively low power consumption. Therefore, there are many advantages that heat generation of the printer head is small and thermal deterioration (so-called kogation) of the ink is small.

The main component of the ink was water or a boiling point of 150.
When the organic solvent is less than [° C.], it is desirable that the structure of the porous structure forming the columnar body group 37G be set in accordance with this. That is, each column of the column group 37G has a height of 1 to 50 [μm], a diameter or a side of 1 to 50 [μm].
And the arrangement interval is preferably about 1 to 50 [μm], particularly 300
It is desirable to use a material having heat resistance of [° C.] or more, and form a pattern arranged in a matrix in the range of 2 to 100 rows and 2 to 100 columns in the vertical and horizontal directions, respectively.

[0079] In addition to performing satisfactorily landing of ink droplets on the printing paper PM, the ink it is necessary to keep safely hold the respective ejection portions 21A ₁ ~21A _N, for the non-recording In some cases, the tip of each columnar body 37G _X , which is a porous structure, is set at 0 to the liquid level of the ink where the meniscus is formed.
It is better to position it 100 [μm] deep. In addition, each discharge portion _21A 1 _{~21A N} and photographic paper PM and gap, 500
[Μm] to about 10 [mm] is desirable.

On the other hand, a case will be described in which the fourth and fifth inks whose main components have a boiling point of 150 ° C. or higher are used in the above-described print head. As shown in FIG. 11, the composition of the fourth ink was Solvent Blue 35
(Solvent Blue 35) is 10% by weight and dibutyl phthalic acid is 90% by weight. In the composition of the fifth ink, Solvent Blue 35 is 10% by weight and dibutyl sebacic acid is 90% by weight.

As shown in FIG. 12, the boiling point of dibutyl phthalic acid as the main component of the fourth ink is 340 ° C., and the boiling point of dibutyl sebacic acid as the main component of the fifth ink is 342 ° C. [° C].

As shown in FIG. 13, the driving conditions of the image printing section 4 are set such that the ejection frequency is set to 3 for the fourth ink.
3.3 (kHz), pulse width 16 (μs), printing cycle 7.6 (m
s], duty ratio 48 [%], pulse power 120 [mW]
And for the fifth ink, the ejection frequency
33.3 (kHz), pulse width 20 (μs), printing cycle 7.6 (m
s], duty ratio 60 [%], pulse power 160 [mW]
And

As a result, as shown in FIG. 14, in the fourth ink, the average droplet diameter was 4.2 [μm] and the flight distance was 0.6 [m
m] and a dot size of 110 [μm], and the fifth ink has an average droplet diameter of 3.6 [μm] and a flight distance of 0.4 [μm].
[Mm] and the dot size were 115 [μm].

Based on these results, the boiling point of the main component was 150
When using [℃] or more of the ink, regardless of the driving conditions, flying distance of the ink ejected from the respective ejection portions 21A ₁ ~21A _N is very difficult to 1 [mm] or more It was confirmed that.

Further, the case where the ink jet system according to the present embodiment is applied to FIGS. 15A to 15D (FIG. 15)
(B) and (D)) and the case where the conventional ink jet system is applied (FIGS. 15A and 15C), the landing state of the ink ejected from the printer heads 13A to 13C on the printing paper PM is shown. Show.

According to the present embodiment, fine dots are dispersed in pixels of 300 [dpi] and a high density pattern (FIG. 1)
5 (B)), there is no graininess in the image, and high gradation suitable for photographic image expression can be obtained.

[0087] Indeed the printer head 13A - 13C, a plurality of ejection portions _21A 1 _{~21A N} formed at an edge portion of the heater chip 21 described above, toluene (boiling point 11
0 [℃]) when ejecting ink whose main component, fine ink droplets of about 3 to 10 [μm] from the respective ejection portions 21A ₁ ~21A _N is a number, flight distance approximately 4 mm. You can see that it flies. The diameter of the ink droplet is determined by the ejection unit 21A.
_{1 ~21A N} depending on the structure of the formed columnar body group 37G is defined, holes in the orifice such is not required.

On the other hand, in the conventional ink jet system, the landing positions on the printing paper are concentrated at one place (see FIG. 1).
5 (A) and (C)), in order to enrich the gradation expression, it is necessary to make the ink droplets small, and a gap is formed between the dots in this state. This cannot be essentially improved by over-striking. Therefore, in the case of this method, there remains a problem that the number of ejection sections per unit length formed on the heater chip 21 must be increased.

(4) Operation and Effect According to the Present Embodiment In the above configuration, in the color printer 1, first, the inks respectively filled with the three color inks whose main components have a boiling point of 150 ° C. or less are used. Tanks 14A-14C
To the corresponding tank holding units 15A to 15A in the image printing unit 4.
It is stored and held in 5C.

Such an ink is prepared, for example, by boiling water, ethyl alcohol or isopropyl alcohol at a boiling point of 150 ° C.
The following main components are used. For each color (yellow, magenta or cyan), a water-soluble dye such as an acid dye or a basic dye, or a pigment containing an appropriate dispersant is used as a coloring material in a predetermined ratio. Are generated by adding

Next, in the image printing section 4, three (for three colors of yellow, magenta and cyan) printer heads 1 are provided.
Each of the head chips 21 provided in the head chips 3A to 13C is heated with a heat amount corresponding to the image information to boil the ink supplied from the corresponding ink tank 14A to 14C to form minute droplets. by flying from a plurality of discharge portions 21A ₁ ~21A _N formed 21 to eject the printing paper PM conveyed the droplets on the platen belt 10.

[0092] By using the ink according this case, the ink droplets ejected from respective ejection portions _21A 1 _{~21A N,} droplet size is in and initial velocity 5-20 [μm] 5-40
[M / s], so that these ink droplets have a flight distance of 200 to 800 [μm]. And by continuously generating drive pulses for heating,
The air flow accompanying the movement of the droplet generated by the subsequent drive pulse boosts the movement of the droplet generated by the previous drive pulse, so that the flight distance can be extended to 1 to 4 [mm].

Thus, each of the printer heads 13A to 13C
In each discharge portion 21A ₁ ~21A _N provided, the ink droplets ejected from the fine holes formed by the columnar body group 37G of the above-described porous structure when compared to the color printer of the conventional ink jet method In addition, it is possible to form a large number of droplets (microdots) having a significantly smaller size than ink droplets ejected from a normal nozzle.

[0094] In addition, each printer head 13A - 13C, is possible to adjust the generation number of droplets in accordance with the applied energy in accordance with image information (i.e. droplet volume of flight) to the discharge portion _21A 1 _{~21A N} By doing so, multi-value density gradation becomes possible, and image quality (full color) equivalent to or higher than that of a silver halide image can be obtained.

According to the above-described configuration, in the color printer 1, the ink tanks 14A to 14C filled with inks of three colors whose main components have a boiling point of 150 ° C. or less are used as the corresponding printer heads 13A to 13C. leave attached to the image printing unit 4 as a supply subject to, in each printer head 13A~13C during printing, it boiled given ink was heated by heat in accordance with image information, a plurality of discharge portions 21A ₁ ~21A _By flying fine droplets from the _N to the photographic paper PM, the flying distance can be increased by an amount corresponding to a higher coefficient of thermal expansion than the conventional ink. Plain paper can also be used in addition to paper, and the versatility can be further increased.

[0096] Also a plurality of discharge portions _21A 1 _{~21A N} provided in each printer head 13A - 13C, was configured from the discharge port of the ink as fine holes formed by the columnar body group 37G of the porous structure it makes it possible to fly by reducing the ink droplet ejected from the respective ejection portions 21A ₁ ~21A _N to the size of the microdots,
As a result, printing can be performed on the printing paper PM with the multi-value density gradation, and the image quality can be further improved.

[0097] Further in this color printer, a plurality of discharge portions _21A provided in each printer head 13A~13C image printing section 4 1 ~21A _N shielding lid 4
0, the eaves 4
By between 0M and wall 40W with the adhesion and dust or the like from the outside is mixed to the respective ejection portions _21A 1 _{~21A N} can be prevented, the respective discharge portions _21A 1 to 2
Ink in 1A _N can be prevented from being dried.

Further, the slits formed between the wall portions 40W of the shield lid 40 allow the respective discharge portions 21A ₁ to 2A ₁ to 2
By which is adapted to generate a meniscus in the ink itself in the columnar body group 37G of 1A _N, it is easily immersed by the columnar body group 37G by its surface tension, stable amount from the respective ejection portions 21A ₁ ~21A _N Ink droplets can be ejected.

(5) Other Embodiments In the above-described embodiment, the main component has a boiling point of 150
[° C.] As the ink composed of the following liquid,
Although the case where the third ink (FIG. 7) is applied has been described, the present invention is not limited to this, and the point is that if the flight distance based on the thermal expansion coefficient of the ink can be sufficiently secured for practical use, the boiling point is 150 ° C.
It can be widely applied to various other inks containing a liquid of [° C.] or less as a main component. As liquids having a boiling point of 150 ° C. or lower, water (H ₂ O) (boiling point 100 ° C.), toluene (boiling point 110 ° C.), and ethanol (boiling point 78)
[° C.]), but can also be widely applied to methyl ethyl ketone (boiling point 80 [° C.]).

In the above-described embodiment, the printer heads (recording heads) 13A to 13C are provided.
It has a columnar group 37G having a porous structure for holding the supplied ink, and has a plurality of discharge units formed on the heater chip 21 for discharging means for applying heat to the columnar group 37G according to image information. it has dealt with the case of composed parts 21A ₁ ~21A _N, the present invention is not limited to this, it may be widely applied to a discharge means comprising various other configurations.

In this case, the structure of the column group is as shown in FIG.
In addition to the square pillars (or cylindrical pillars, etc.) each having 13 columns and 13 columns as described above with reference to FIG. As long as it has a porous structure, those having columnar bodies of various shapes and sizes arranged at predetermined intervals can be widely applied.

Further, in the above-described embodiment, a plurality of discharge portions (discharge means) formed on the heater chip 21 are provided.
Formed in 21A ₁ ~21A _N, as a cover material of a predetermined shape having an opening corresponding to the columnar body group 37G covers the ink channel, dealt with the case of applying the shield cover 40 (FIG. 4) However, the present invention is not limited to this. In short, it is possible to prevent dust and the like from being mixed and adhered to the ejection means, and to prevent the ink in the ejection means from drying. Can be widely applied to lid members having various other configurations.

Further, in the above-described embodiment, a plurality of ejection portions (ejection means) formed on the heater chip 21 are provided.
Is formed around the columnar body group 37G of 21A ₁ ~21A _N, as a wall material having a slit for generating a meniscus of the ink at the tip of the columnar body group 37G, the wall portion 40W of the shielding lid 40 of the above Although the description has been given of the case where the present invention is applied, the present invention is not limited to this.
If a meniscus can be generated in the ink itself in the column group by the slit, it can be widely applied to wall materials having various other configurations.

Further, in the above-described embodiment, a case has been described in which the present invention is applied to an ink jet type color printer capable of multi-value gradation density, but the present invention is not limited to this, Can be widely applied to various color printers as long as they are printing apparatuses that discharge ink droplets of microdots.

[0105]

As described above, according to the present invention, the ink supplied to the recording head is caused to fly as droplets by applying heat in accordance with image information, and the droplets are applied to the printing medium facing the recording head. In a printing apparatus that performs a printing operation by attaching the ink, the boiling point of the main component of the ink is set to a liquid of 150 ° C. or less, so that the thermal expansion coefficient of the ink is higher than that of the conventional ink. By increasing the flight distance, the versatility of the printing medium can be increased, and thus a printing apparatus capable of significantly improving printing efficiency can be realized.

According to the present invention, the ink supplied to the recording head is caused to fly as droplets by applying heat in accordance with image information, and the droplets are attached to the printing medium facing the recording head. In a printing apparatus that performs a printing operation, a discharge unit that is provided on a print head and has a column group having a porous structure for holding supplied ink, and that applies heat to the column group according to image information And a cover member of a predetermined shape formed in the discharge means and covering the ink flow path and having an opening corresponding to the column group, so that dust and the like are mixed from the outside and adhere to the discharge means. Can be prevented beforehand, and the ink in the ejection unit can be prevented from drying out, thus realizing a printing apparatus capable of remarkably improving printing efficiency.

Further, according to the present invention, the ink supplied to the recording head is caused to fly as droplets by applying heat in accordance with the image information, and the droplets are attached to the printing medium facing the recording head. In a printing apparatus that performs a printing operation, a printing apparatus includes a column group having a porous structure for holding ink to be supplied, which is provided on a recording head, and discharges the column group with a heat amount according to image information. Means and a wall member formed around the column group of the discharge means and having a slit for generating a meniscus of the ink at the tip of the column group, the ink itself is formed in the column group by the slit. The ink can be more easily immersed in the column group due to the surface tension of the meniscus generated at the time, and as a result, a stable amount of ink droplets can be discharged from the ejection unit. Out it is possible to, thus the printing apparatus can be realized which can improve the printing efficiency and remarkably.

Further, according to the present invention, the ink supplied to the recording head is caused to fly as droplets by applying heat in accordance with image information, and the droplets are attached to the printing medium facing the recording head. In the printing method for performing the printing operation, by setting the boiling point of the main component of the ink to a liquid of 150 ° C. or lower, the flying distance is increased by an amount corresponding to the coefficient of thermal expansion of the ink being higher than that of the conventional ink. As a result, the versatility of the printing medium can be increased, and thus a printing method capable of significantly improving the printing efficiency can be realized.

[Brief description of the drawings]

FIG. 1 is a partial perspective view illustrating a configuration of a color printer according to an embodiment.

FIG. 2 is a schematic perspective view showing the configuration of the printer head shown in FIG.

FIG. 3 is a schematic diagram illustrating a configuration of a printer head.

FIG. 4 is a partial cross-sectional view illustrating a configuration of each discharge unit.

FIG. 5 is a partial top view showing the configuration of each discharge unit.

FIG. 6 is a schematic cross-sectional view for explaining the positional relationship between the printer head and the printing paper.

FIG. 7 is a chart showing the composition of the ink.

FIG. 8 is a table showing the boiling points of the main components of the ink.

FIG. 9 is a table showing driving conditions set for each ink.

FIG. 10 is a table showing ejection and image evaluation for each ink.

FIG. 11 is a chart showing the composition of ink.

FIG. 12 is a chart showing boiling points of main components of ink.

FIG. 13 is a table showing driving conditions set for each ink.

FIG. 14 is a table showing ejection and image evaluation for each ink.

FIG. 15 is a schematic plan view for explaining an ink landing state on photographic printing paper.

[Explanation of symbols]

1 ... Color printer, 4 ... Image printing section, 10 ... Platen belt, 13A to 13C ... Printer head, 1
4A～14C ...... ink tank, 15A to 15C ...... tank holder, 20 ...... head base, 21 ...... heater _chip, 21A 1 _{~21A N} ...... discharge unit, 22 ...... _PCB, 22A 1 _{~22A K} ...... Driver IC, 37G
... Column group, 37W Partition wall, 40 Shield lid, 40M Eaves, 40W Wall part, IF ink passage, PM photographic paper.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C056 FA03 FC01 2C057 AF51 AG12 AG46 AG51 AM15 AM16 CA01 2H086 BA02 BA52 BA60

Claims (5)

[Claims] A printing operation is performed by causing ink supplied to a recording head to fly as droplets by applying heat in accordance with image information, and causing the droplets to adhere to a printing medium facing the recording head. A printing apparatus, wherein the boiling point of the main component of the ink is set to a liquid of 150 ° C. or lower. 2. A printing operation is performed in which ink supplied to a recording head is jetted as droplets by applying heat in accordance with image information, and the droplets are attached to a printing medium facing the recording head. In a printing apparatus, a discharge unit provided on the recording head and having a columnar group having a porous structure for holding the supplied ink, and applying a heat amount to the columnar group according to the image information; and And a cover member of a predetermined shape formed on the discharge means and covering the ink flow path and having an opening corresponding to the column group. 3. A wall member formed on the cover member as a peripheral wall of the column group, and having a slit at a tip of the column group for generating a meniscus of the ink. Item 3. The printing apparatus according to Item 2. 4. A printing operation is performed in which the ink supplied to the recording head is caused to fly as droplets by applying heat in accordance with image information, and the droplets are attached to a printing medium facing the recording head. A printing apparatus, comprising: a column group having a porous structure provided on the recording head and configured to hold the supplied ink; and a discharge unit configured to heat the column group with a heat amount according to the image information. And a wall material formed around the column group of the ejection unit and having a slit at the tip of the column group for generating a meniscus of the ink. 5. A printing operation is performed in which ink supplied to a recording head is jetted as droplets by applying heat in accordance with image information, and the droplets are attached to a printing medium facing the recording head. In the printing method, the boiling point of the main component of the ink is set to a liquid of 150 ° C. or lower.