ROTARY PRESS FOR FOUR-COLOR DOUBLE-SIDE PRINTING Technical Field The present invention relates to a rotary press of four- color double-side printing, and more particularly, to a rotary press of four-color double-side printing in which the tension of paper passing through the first through fourth printing units is always maintained to be constant, and position of a printing pin of each printing unit is consistently maintained to thus prevent a pin secession phenomenon of a printed image from occurring, in such a manner that an output image of the rotary press becomes clear, and in which a first color and a second color are printed all at a time on one surface of the printing paper in the first printing unit, and the first color and the second color are printed all at a time on the other surface of the printing paper in the fourth printing unit, to thereby make it much easier to fit color pins.

Background Art In general, a rotary press means an apparatus which prints at high speed on printing materials such as newspaper, magazine and pamphlet.

FIGs. 3 and 4 is a schematic view showing a conventional rotary press, respectively. FIG. 3 is a schematic view showing a conventional rotary press for newspaper printing to

print at high speed on newspaper, and FIG. 4 is a schematic view showing a conventional commercial rotary press for printing at high speed on printing materials such as magazine and pamphlet.

Referring to FIGs. 3 and 4, a conventional rotary press includes first and fourth printing units 1-4 which print different colored characters or figures on double sides of printing paper, respectively.

In each of the printing units 1-4, a pair of plate cylinders 5 and 6 are installed to oppose each other and a pair of blanket cylinders 7 and 8 are installed to oppose each other, in order to print on respectively different sides.

Here, printing paper 9 passes through between the blanket cylinders 7 and 8 which oppose and contact each other.

In the case of the conventional rotary press having the above-described configuration, respectively different characters or figures are printed on the double sides of the printing paper 9 by the blanket cylinders 7 and 8 when the printing paper 9 passes through between the blanket cylinders 7 and 8 of each of the printing units 1-4.

That is, when printing paper 9 passes through the first printing unit 1, first colored characters or figures are printed on the double sides of the printing paper 9 by the blanket cylinders 7 and 8 in the first printing unit 1. When the printing paper 9 having passed through the first printing unit 1 passes through the second printing unit 2, second

colored characters or figures are printed in the second printing unit 2. Thereafter, when the printing paper 9 passes through the third and fourth printing units 3 and 4, third and fourth colored characters or figures are respectively printed on the double sides of the printing paper 9.

However, since printing paper passes through between blanket cylinders in a linear contacting manner when passing through each printing unit in the conventional rotary press, color pins are seceded due to moving of the printing paper at the time of changing in speed or tension of the printing paper to be fed, to thereby lower positional correctness of characters or figures of different colors which are printed on printing paper, and thus prevent accurate printing due to mismatched focus of contents to be finally printed, or occurring of pin secession.

In particular, newspaper is severely expanded due to ink and moisture which are supplied during printing in a newspaper rotary press and thus a printing effect becomes further lowered.

Disclosure of the Invention To solve the above problems, it is an object of the present invention to provide a rotary press for four-color double-side printing in which direct-printing cylinders for printing directly on paper are formed in first and fourth

printing units, respectively, and thus printing paper supplied to the first printing unit passes through the direct-printing cylinder and wound to contact a blanket cylinder in a surface-to-surface contacting manner, to then be supplied to a second printing unit and a third printing unit, in turn, and printing paper discharged from the fourth printing unit also contacts a blanket cylinder in a surface- to-surface contacting manner and then be discharged via a direct-printing cylinder, to accordingly always maintain the tension of paper passing through the first through fourth printing units to be constant, and consistently maintain position of a printing pin of each printing unit to thus prevent a pin secession phenomenon of a printed image from occurring, in such a manner that an output image of the rotary press becomes clear, and also print a first color and a second color all at a time on one surface of the printing paper in the first printing unit, and print the first color and the second color all at a time on the other surface of the printing paper in the fourth printing unit, to thereby make it much easier to fit color pins.

To accomplish the above object of the present invention, according to an aspect of the present invention, there is provided a rotary press for four-color double-side printing including first through fourth printing units each having a number of blanket cylinders and plate cylinders, the rotary press characterized in that each of the first and fourth

printing units comprises a pair of blanket cylinders, a plate cylinder and a direct-printing cylinder, wherein printing paper is guided and transferred by guide rollers to then pass through between one of the blanket cylinders and the direct- printing cylinder in the first printing unit and contact the blanket cylinder in a surface-to-surface contacting manner, and to then be supplied to second and third printing units in turn while passing through different pairs of blanket cylinders, and wherein printing paper having passed the third printing unit passes through between the blanket cylinders in the fourth printing unit and contacts one of the blanket cylinders in a surface-to-surface contacting manner to then be discharged between the one of the blanket cylinders and the direct-printing cylinder, to thereby consistently maintain tension of the printing paper passing through the first through fourth printing units.

Preferably, a first color and a second color are printed on one side of printing paper by the direct-printing cylinder and the blanket cylinders in the first printing unit, a third color and a fourth color are printed on the double sides of the printing paper in the second and third printing units, respectively, and the first color and the second color are printed on the other side of the printing paper by the direct-printing cylinder and the blanket cylinders in the fourth printing unit.

Brief Description of the Drawings The above and other objects and advantages of the present invention will become more apparent by describing the preferred embodiment thereof in more detail with reference to the accompanying drawings in which: FIG. 1 is a schematic view showing a rotary press of four-color double-side printing according to the present invention ; FIG. 2 is a schematic view showing a state where a rotary press of four-color double-side printing according to the present invention is applied to a commercial rotary press; FIG. 3 is a schematic view showing a conventional rotary press of printing on newspaper ; and FIG. 4 is a schematic view showing a conventional commercial rotary press.

Best Mode for Carrying out the Invention Hereinbelow, a rotary press according to the present invention will be described with reference to the accompanying drawings FIGs. 1 and 2.

FIG. 1 is a schematic view showing a state where a rotary press of four-color double-side printing according to the present invention is applied to a newspaper printing rotary press. FIG. 2 is a schematic view showing a state where a rotary press of four-color double-side printing according to the present invention is applied to a commercial rotary press.

A rotary press according to the present invention includes first through fourth printing units 10-40. In each of the second and third printing units 20 and 30, a pair of blanket cylinders 21 and 22; 31 and 32 are installed to oppose each other and a pair of plate cylinders 23 and 24 ; 33 and 34 are installed to oppose each other, like the conventional art. Here, printing paper 50 passes through between the opposing blanket cylinders 21 and 22; 31 and 32 which oppose and contact each other, to then be printed thereon.

The first printing unit 10 includes a pair of blanket cylinders 11 and 13, a plate cylinder 12, and a direct- printing cylinder 14. One blanket cylinder 11 contacts the other blanket cylinder 13 side by side. The direct-printing cylinder 14 for printing characters or figures of a first color on one surface of the printing paper is installed in contact with the blanket cylinder 13. A plurality of guide rollers 51 and 52 are installed at a proper interval at the rear side of the direct-printing cylinder 14. The printing paper 50 advances between the blanket cylinder 13 and the direct-printing cylinder 14 from the rear side of the first printing unit 10 and contacts the blanket cylinder 13 in a surface-to-surface contacting manner, to then pass through between the blanket cylinders 11 and 13 which contact each other.

Meanwhile, the fourth printing unit 40 includes a pair of

blanket cylinders 41 and 43, a plate cylinder 42, and a direct-printing cylinder 44. One blanket cylinder 41 contacts the other blanket cylinder 43 side by side. The direct-printing cylinder 44 for printing characters or figures of the first color on the other surface of the printing paper is installed in contact with the blanket cylinder 43. A plurality of guide rollers 53 and 54 are installed at a proper interval at the front side of the direct-printing cylinder 44. The printing paper 50 having passed through the third printing unit 30 advances between the blanket cylinders 41 and 43 and wound around the one blanket cylinder 43 in a surface-to-surface contacting manner, to then pass through between the one blanket cylinder 43 and the direct-printing cylinder 44.

As described above, when printing paper 50 is fed into the first printing unit 10, the printing paper 50 contacts the blanket cylinder 13 in a surface-to-surface contacting manner.

Also, when the printing paper 50 is discharged through the fourth printing unit 40, the printing paper 50 contacts the blanket cylinder 13 in a surface-to-surface contacting manner, and guided by the guide rollers 53 and 54 at a state where a frictional force with the printing paper 50 is increased, and then discharged. Accordingly, tension of the printing paper in the first through fourth printing units 10-40 is always consistently maintained although moving speed of the printing paper 50 is changed. As a result, positions of setting color

pins of different colors which are printed in the respective printing units 10-40 are not changed, to thus decrease a pin secession phenomenon of printing matters, enhance accuracy of printed images, and reduce a loss of paper.

Meanwhile, four colored characters or figures are changed in a printing sequence in the present invention.

That is, when printing paper 50 is fed into the first printing unit 10, and passes through between the blanket cylinder 13 and the direct-printing cylinder 14, first colored characters or figures are printed on one side of the printing paper 50. Also, when the printing paper 50 having passed through between the direct-printing cylinder 14 and the blanket cylinder 13 passes through between the blanket cylinders 11 and 13, second colored characters or figures are printed on the one side of the printing paper 50 by the blanket cylinder 11. Also, when the printing paper 50 having passed through the first printing unit 10 passes through the second and third printing units 20 and 30 in turn, third and fourth colored characters or figures are printed on the double sides of the printing paper 50 by the blanket cylinders 21 and 22 ; 31 and 32, respectively.

Also, when the printing paper 50 having passed through the third printing unit 30 passes through the fourth printing unit 40, the first and second colored characters or figures are printed on the other side of the printing paper 50 by the blanket cylinder 41 and the direct-printing cylinder 44.

As described above, the first and second colored characters and figures are printed all at a time on the one side of the printing paper in the first printing unit 10, and the first and second colored characters and figures are printed all at a time on the other side of the printing paper in the fourth printing unit 40. Accordingly, four-color printing is accomplished through three printing units in view of the whole printing effect. As a result, color pins in each printing unit match well to thus enable a printing quality of printed matters to be excellent.

As described above, a moving path of the printing paper 50 is changed and the printing paper 50 contacts a particular blanket cylinder in a surface-to-surface contacting manner in the first and fourth printing units, in the present invention.

As a result, change in tension of the printing paper 50 is reduced, and thus a printing quality of printed matters is enhanced, to thereby remarkably reduce a loss of printing paper. Also, since the first and second colored characters and figures are printed all at a time on the one side of the printing paper in the first printing unit 10, and the first and second colored characters and figures are printed all at a time on the other side of the printing paper in the fourth printing unit 40, color pins in each printing unit fit well to thus enable a printing quality of printed matters to be further excellent.

Industrial Applicability As described above, the present invention provides a rotary press, in which direct-printing cylinders 14 and 44 for printing directly on paper are formed in first and fourth printing units 10 and 40, respectively. Here, printing paper 50 supplied to the first printing unit 10 passes through the direct-printing cylinder 14 and wound to contact a blanket cylinder 13 in a surface-to-surface contacting manner, to then be supplied to a second printing unit 20 and a third printing unit 30, in turn. Then, printing paper discharged from the fourth printing unit 40 also contacts a blanket cylinder in a surface-to-surface contacting manner and then be discharged via a direct-printing cylinder. Accordingly, the tension of paper passing through the first through fourth printing units 10-40 is always maintained to be constant, and position of a printing pin of each printing unit is consistently maintained to thus prevent a pin secession phenomenon of a printed image from occurring, in such a manner that an output image of the rotary press becomes clear.

Also, a first color and a second color are printed all at a time on one surface of the printing paper in the first printing unit, and a third color and a fourth color are printed all at a time on the other surface of the printing paper in the fourth printing unit, to thereby make it much easier to fit color pins so that a pin secession rate of a printed image is further decreased.

As described above, the present invention has been described with respect to a particularly preferred embodiment.

However, the present invention is not limited to the above embodiment, and it is possible for one who has an ordinary skill in the art to make various modifications and variations, without departing off the spirit of the present invention.