JPH09141901A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance print quality and to maintain a prescribed resolution when gradation printing is executed. SOLUTION: This device comprises a plurality of ink reservoirs having respective orifices 12Y, 12M, 12C, 12B at each of tips, inks each having respective color contained in the respective reservoirs and ink droplet generating means each ejects each of the inks from the respective orifice 12Y, 12M, 12C, 12B by creating the ink droplets. At least two of ink reservoirs are provided toward directions such that ink droplets are united with each other until the droplets reach a recording medium. Then, ink droplets ejected from at least two ink reservoirs, respectively are united with each other until the droplets reach the recording medium 16 to become a droplet having another color to be adhered to the medium 16. When one dot is formed, the inks are mixed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording device for performing color printing.

[0002]

2. Description of the Related Art Conventionally, in an ink jet recording apparatus for performing color printing, four color inks of, for example, yellow, magenta, cyan and black are ejected as ink droplets from an orifice of an ink jet head.
Ink droplets of each color are superimposed on the print medium so that a desired color is expressed.

Therefore, the ink jet head is provided with an ink drop generating means such as a heating element and a piezoelectric element, and by driving the ink drop generating means based on color information, ink drops of a corresponding color are ejected. It Further, when performing gradation expression, one pixel is configured by a matrix of 4 × 4 dots, etc., and the print density can be changed for each pixel.

[0004]

However, in the above-mentioned conventional ink jet recording apparatus, it is difficult to accurately superimpose the ink droplets of each color on the print medium, resulting in dot misregistration, color misregistration, bleeding, etc. Print quality is degraded. Further, in the case of gradation expression, if printing is performed for each pixel, the resolution of the inkjet recording apparatus will be reduced accordingly.

According to the present invention, the problems of the conventional ink jet recording apparatus are solved, dot deviation, color deviation, bleeding, etc. do not occur, the printing quality can be improved, and gradation expression is possible. It is an object of the present invention to provide an inkjet recording device in which the resolution does not decrease when performing the above.

[0006]

To this end, in the ink jet recording apparatus of the present invention, a plurality of ink containing portions each having an orifice at its tip, each color ink contained in each ink containing portion, and each ink containing portion And an ink droplet generating means for disposing each ink as an ink droplet and ejecting it from the orifice.

At least two or more of the ink accommodating portions are arranged in a direction in which the ink droplets are merged by the time they reach the print medium.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view of an inkjet head according to the first embodiment of the present invention, FIG. 2 is a view showing a first state of the inkjet head according to the first embodiment of the present invention, and FIG. FIG. 4 is a diagram showing a second state of the inkjet head according to the first embodiment, and FIG. 4 is a diagram showing a third state of the inkjet head according to the first embodiment of the present invention.

In the figure, 11Y is an ink pressure chamber containing yellow ink, 11M is an ink pressure chamber containing magenta ink, 11C is an ink pressure chamber containing cyan ink, and 11B is black ink. And an ink pressurizing chamber for accommodating each of the ink pressurizing chambers 11Y and 11Y.
M, 11C, and 11B respectively form an ink containing portion, and orifices 12Y, 12M, 12C, and 12B of about 30 to 50 [μ] are formed at their tips.

The ink pressurizing chambers 11Y and 11Y
Piezoelectric bodies 13Y, 13M, 13C and 13B as ink droplet generating means are respectively arranged on the outer circumferences of M, 11C and 11B, and the piezoelectric bodies 13Y, 13M, 13C and 13B have wirings 14Y, 14M, 14C and 14B. It is connected to the power supply V via each and is driven based on the color information of the print data.

By the way, on the head portion 15, the ink pressurizing chamber 11B is disposed on a line k1 extending in a direction substantially perpendicular to the print medium 16, and the ink pressurizing chambers 11Y, 11M ,. 11C is each orifice 12
Y, 12M, 12C and the distance L ₁ smaller than the distance L ₂ only lines intersect each at a remote point P1 k with the print media 16
It is arranged on 2, k3 and k4. The distance from the line k1 where the ink pressurizing chamber 11B is arranged to the point P1 is L
_Set to ₃ .

Further, the angle formed by the lines k2 and k3 and the angle formed by the lines k3 and k4 are defined as θ. And
Based on the color information, the substantially cylindrical piezoelectric bodies 13Y, 1
When 3M, 13C and 13B are driven, the piezoelectric body 13Y,
13M, 13C, 13B contract, and the ink pressurizing chamber 11Y,
The inks contained in the ink pressurizing chambers 11Y, 11M, 11C, and 11B are pressurized by deforming 11M, 11C, and 11B. As a result, the orifices 12Y, 12
Ink can be ejected from M, 12C, and 12B as ink droplets and deposited on the print medium 16 to form dots.

By the way, printing with only black ink
When performing, as shown in FIG. 2, from the orifice 12B
Volume is about m₁Of black ink drop 17B
It is. Also, for example, yellow ink and cyan ink
If you want to print green by mixing with
And the volume from the orifice 12Y is approximately m_Two= 1/2 m₁of
The yellow ink drop 17Y is discharged from the orifice 12C to the body.
Product is about m_Two= 1/2 m ₁17C of cyan ink drop
It is jetted at the same time. And the ink droplet 1
7Y and 17C fly on lines k2 and k4, respectively, and
Merge at P1. As a result, as shown in FIG.
Volume is about m₁17G of green ink drops, and print medium 1
6 in a direction perpendicular to 6 and printed on the print medium 16
Form dots.

Next, the drive timing of the ink jet head will be described. FIG. 5 is a diagram showing drive timing of the inkjet head according to the first embodiment of the present invention, and FIG. 6 is a block diagram of the inkjet head according to the first embodiment of the present invention. As shown in the figure, the CPU 20 includes a yellow timer 21Y, a magenta timer 21M, a cyan timer 21C, and a black timer 2
1B, yellow head driver 22Y, magenta head driver 22M, cyan head driver 22C
And a black head driver 22B are respectively connected, and the yellow head driver 22Y, the magenta head driver 22M, the cyan head driver 22C, and the black head driver 22B connect the piezoelectric bodies 13Y and 1B.
3M, 13C and 13B are driven respectively.

The CPU 20 includes timing correction means (not shown), which includes the yellow timer 21Y, magenta timer 21M and cyan timer 2.
1C and the black timer 21B, the piezoelectric body 13Y,
Set pulse correction values for driving 13M, 13C, and 13B, respectively. As a result, a drive pulse is generated by the tamming corrected by each pulse correction value, and the piezoelectric body 13Y, 13M,
13C and 13B are driven respectively.

Next, the pulse correction value will be described. In this case, the number of driving cycles of the inkjet head is 5 [kHz], and the resolution of the inkjet recording device is 300 [dpi] (print dot pitch is 85 [μ
m]). As shown in FIG. 5, the cycle of the basic drive pulse is 1/5000 [sec] = 200 [μsec]. When the black pulse correction value t _B is t _B = 0, the yellow pulse correction value t _Y is t _Y = 200/85 {L ₃ + (L ₁ −L ₂ ) tan θ}, and the magenta pulse is The correction value t _M is t _M = 200/85 · L ₃ , and the cyan pulse correction value t _C is t _C = 200/85 {L ₃ − (L ₁ −L ₂ ) tan θ}.

The pulse correction value t _{Y + M} when yellow and magenta are mixed is t _{Y + M} = 200/85 {L ₃ + (L ₁ -L ₂ ) tan θ
/ 2}, and the pulse correction value t _{Y + C} when mixing yellow and cyan is t _{Y + C} = t _M = 200/85 · L ₃ , and the pulse correction value when mixing magenta and cyan t _{M + C} is t _{M + C} = 200/85 {L ₃ − (L ₁ −L ₂ ) tan θ
/ 2}.

As described above, in the present embodiment, ink droplets of a required color are formed until the print medium 16 (FIG. 1) is almost reached, and printing is performed with only one color ink droplet. In either case, the ink amounts of the ink droplets at the time of reaching the print medium 16 are made equal in both cases of performing the printing by combining the ink droplets of a plurality of colors. Therefore,
No dot shift, color shift, bleeding, etc.
The printing quality can be improved.

Next, a second embodiment of the present invention will be described. FIG. 7 is a first diagram showing the relationship between drive pulses and ink droplets in the second embodiment of the present invention, and FIG. 8 shows the relationship between drive pulses and ink droplets in the second embodiment of the present invention. FIG. 2 and FIG. 9 are views showing the state of the inkjet head according to the second embodiment of the present invention. In addition, about the thing which has the same structure as 1st Embodiment, the description is abbreviate | omitted by giving the same code | symbol.

In this case, for example, when printing is performed with black ink, the pulse width adjusting means (not shown) of the CPU 20 (FIG. 6) adjusts the drive pulse width of the piezoelectric body 13B as shown in FIG. , A small diameter ink drop 17 from the orifice 12B of the ink pressurizing chamber 11B.
B _S is ejected, or as shown in FIG. 8, an ink droplet 17 having a large diameter is ejected from the orifice 12B of the ink pressurizing chamber 11B.
B _L can be ejected.

Also, when printing is performed with inks of other colors, similarly, the pulse width adjusting means of the CPU 20 adjusts the drive pulse widths of the piezoelectric bodies 13Y, 13M and 13C, respectively, so that the ink drops 17Y, 17M, 17
The diameter of C can be changed. Accordingly, as shown in FIG. 9, the diameter is large volume ink droplets 17Y of yellow is m _{3 L,} diameter small volume ink droplets 17C _S cyan is m _4, be combined at point P1 Gives a yellow-green ink drop 17Y _L + with a volume of m ₅
17C _S is formed. At this time, the ink drop 17Y _L
The volumes m ₄ and m _{5 of the} ink droplets 17Y _L and 17C _S are adjusted so that the volume m ₅ of + 17C _S is substantially equal to the volume m ₁ of the normal ink droplet.

In addition, the ink drop 17Y after the coalescence_L+ 17C
_SIs each ink drop 17Y_L, 17C _SDetermined by the volume ratio of
Fly in the direction of the angle α. Then, based on the angle α
Then, the pulse of the drive timing of the piezoelectric body 13Y, 13C
The correction value is determined. 11Y is yellow ink
The pressure chamber 11C is a cyan ink pressure chamber. Soshi
In the case of gradation expression, only one color ink droplet or multiple
Adjusting the amount of ink in a drop of mixed color
Thus, fine gradation expression can be performed.

As described above, by adjusting the amount of each color ink, gradation expression can be performed with only one dot, so that not only the resolution of the ink jet recording apparatus can be increased but also dot deviation, Printing quality can be improved without causing color misregistration or bleeding. Next, a third embodiment of the present invention will be described.

FIG. 10 is a schematic view of an ink jet head according to the third embodiment of the present invention. In addition, about the thing which has the same structure as 1st Embodiment, the description is abbreviate | omitted by giving the same code | symbol. In this case, the ink pressurizing chamber 11B is arranged on a line k1 extending in a direction substantially perpendicular to the print medium 16, and if the point at which the line k1 and the print medium 16 intersect is P2, a black ink drop is formed. Adheres to the print medium 16 at point P2. Further, each of the ink pressure chambers 11Y, 11M, 11C, each orifice 12Y, 12M, 12C and the line intersects each at a distance L ₁ smaller than the distance L ₂ spaced points P1 with the print media 16 k5, k6, k7 above Is installed in. Therefore,
When the ink drops of each color fly at the point P1 without coalescing, the yellow ink drop is deposited on the print medium 16 at the point P3 closest to the point P2.

Then, the distance from the line k1 in which the ink pressurizing chamber 11B is arranged to the point P1 is L ₃ , the distance from the point P2 to the point P3 is L ₄ , and the lines k5 and k6 are When the angle formed by the line k6 and the line k6 and the line k7 is θ, the resolution is, for example, 300 [dp] so that the distance L ₄ is larger than the resolution of the inkjet recording apparatus.
In the case of i], the distance L ₃ and the angle θ are set so as to be 85 μm or more.

Therefore, when the yellow ink droplet is accidentally ejected during the printing of black, or when the cyan ink droplet and the yellow ink droplet are not combined, the yellow ink droplet is discharged. Even if a dot is formed on the print medium 16 at a position close to the black ink droplet, the yellow ink droplet has a light color, and therefore has little influence on the dot formed by the black printing. As a result, it is possible to mitigate the damage to black-based document printing. In addition, when the ink droplets of other colors are ejected by mistake, when the ink droplets of other colors and the yellow ink droplets are not combined, the ink droplets of other colors may adhere to the print medium 16. However, since there is a low probability of adhering to a position close to a black ink drop, it has little influence on dots formed by black printing.

By the way, the flight speed of each color ink drop is
Variations in the characteristics of the piezoelectric bodies 13Y, 13M, 13C, and 13B cause variations in a certain range. In addition, the yellow and cyan ink droplets 17Y _L in FIG.
When the set speed of 17C _S is V _O , each ink drop 17
The set values of the kinetic energy of Y _L and 17C _S are m _{3 VO} and m _{4 VO} , respectively. However, each ink drop 17Y _L, respectively variation occurs in flying speed of 17C _S V _Y, becomes a V _C, the ink drop 17Y _L, 17
The kinetic energies of C _S are m ₃ V _Y and m ₄ respectively.
It becomes V _C.

Therefore, the angle α in the flight direction of the ink droplets 17Y _L + 17C _S after the combination shown in FIG. 9 is different from the calculated value. Therefore, the ink droplets after the coalescence are the print medium 16
A fourth embodiment will be described in which the points attached to are corrected. FIG. 11 is a circuit diagram of a piezoelectric body according to the fourth embodiment of the present invention.

In the figure, V is the power supply voltage, 13Y, 13
M, 13C and 13B are piezoelectric bodies, R is the piezoelectric bodies 13Y and 1
3M, 13C, 13B fixed resistance, 25Y _R , 25
M _R, 25C _R, 25B _R is a variable resistor as a driving voltage adjusting means. In this case, the piezoelectric bodies 13Y, 13M,
The drive voltage applied to 13C and 13B is set to each variable resistor 25.
Adjust by Y _R , 25M _R , 25C _R , 25B _R ,
The amount of deformation of each of the piezoelectric bodies 13Y, 13M, 13C, 13B is adjusted. Therefore, the flight velocity V _Y of each ink drop,
The print medium 1 is modified by correcting V _M , V _C , and V _B to the set speed V _O.
The position where the ink droplet adheres to 6 (FIG. 1) is made proper.

Further, the pulse correction values t _B , t _Y , shown in FIG.
By setting t _M , t _C , t _{Y + M} , t _{Y + C} , and t _{M + C} , the position where the ink droplets adhere to the print medium 16 can be made more appropriate. It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified based on the gist of the present invention, and these are not excluded from the scope of the present invention.

[0031]

As described above in detail, according to the present invention, in an ink jet recording apparatus, a plurality of ink containing portions having orifices at the tips thereof and inks of respective colors contained in the ink containing portions are provided. And an ink droplet generating unit that is disposed in each ink storage unit and that ejects each ink as an ink droplet from the orifice.

At least two or more ink storage portions of the ink storage portions are arranged in a direction in which the ink droplets are merged by the time they reach the print medium.
In this case, the ink droplets ejected from the orifices of at least two or more ink accommodating portions are combined into ink droplets of another color before reaching the print medium, and are attached to the print medium.

Therefore, since the respective colors are mixed by forming the dots once, dot deviation, color deviation, bleeding, etc. do not occur, and the printing quality can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an inkjet head according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a first state of the inkjet head according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a second state of the inkjet head according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a third state of the inkjet head according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a drive timing of the inkjet head according to the first embodiment of the present invention.

FIG. 6 is a block diagram of an inkjet head according to the first embodiment of the present invention.

FIG. 7 is a first diagram showing a relationship between drive pulses and ink droplets according to the second embodiment of the present invention.

FIG. 8 is a second diagram showing a relationship between drive pulses and ink droplets according to the second embodiment of the present invention.

FIG. 9 is a diagram showing a state of an inkjet head according to a second embodiment of the present invention.

FIG. 10 is a schematic diagram of an inkjet head according to a third embodiment of the present invention.

FIG. 11 is a circuit diagram of a piezoelectric body according to a fourth embodiment of the present invention.

[Explanation of symbols]

16 print medium 20 CPU 11Y, 11M, 11C, 11B Ink pressurizing chamber 12Y, 12M, 12C, 12B Orifice 13Y, 13M, 13C, 13B Piezoelectric body 17Y, 17M, 17C, 17B, 17G, 17Y _L ,
17C _S, 17B _L, 17B _S ink droplets _{25Y R, 25M R, 25C R} , 25B R variable resistor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhiko Shimosugi, 4-11-21 Shibaura, Minato-ku, Tokyo In stock data off the stock company (72) Inventor Shigenori Koido 4--11-22 Shibaura, Minato-ku, Tokyo No. Stock Company Oki Data

Claims (7)

[Claims] 1. A plurality of ink containing portions each having an orifice at a tip thereof, (b) each color ink contained in each ink containing portion, and (c) each ink containing portion provided in each ink containing portion. Ink droplet generating means for ejecting ink from the orifice into ink droplets, and (d) at least two or more ink containing portions of the ink containing portion until the ink droplets reach the print medium. An ink jet recording apparatus, characterized in that the ink jet recording apparatus is arranged so as to be merged in between. 2. The black ink containing portion of the ink containing portion is arranged in a direction substantially perpendicular to the print medium, and the black ink droplets are combined with other color ink droplets. The method according to claim 1, wherein the print medium is attached to the print medium without being attached.
3. The ink jet recording apparatus according to claim 1. 3. The amount of ink in ink droplets at the time of reaching a print medium is made equal between the case of printing with ink droplets of one color and the case of printing by combining ink droplets of a plurality of colors. The inkjet recording apparatus according to claim 1, wherein 4. The ink jet recording apparatus according to claim 1, wherein the ink droplet generation unit includes a timing correction unit that corrects a timing of generating a drive pulse. 5. The ink jet recording apparatus according to claim 1, wherein the ink droplet generating unit includes a pulse width adjusting unit that adjusts a drive pulse width. 6. The ink jet recording apparatus according to claim 1, wherein the ink droplet generating unit includes a drive voltage adjusting unit that adjusts a drive voltage. 7. The inkjet according to claim 2, wherein the black ink storage portion and the yellow ink storage portion are arranged at positions close to each other on a print medium in a direction in which respective ink droplets are attached. Recording device.