BACKGROUND ART Generally, conventional vinyl printing systems typically use a block printing technique, so that the conventional vinyl printing systems have a desired simple construction. However, since block

printing presses used in the conventional vinyl printing systems of the block printing types must use thin ink, the conventional vinyl printing systems inevitably use large-sized driers to dry the thin ink after printing. Furthermore, since it is very difficult to appropriately control the tension and feeding speed of a vinyl sheet during a printing process of the conventional vinyl printing systems using the block printing processes, the conventional vinyl printing systems cannot qyickly or precisely align the block printing press with each of designated positions on the vinyl sheet, Thus, the conventional vinyl systems fail to accomplish a quick printing process, but increase the amount of poorly printed vinyl sheets to reduce the printing productivity and thus increasing printing costs.

DISCLOSURE OF THE INVENTION Accordingly, it is an aspect of the present invention to provide a vinyl printing system which uses a lithographic press, thus remarkably reducing printing costs, prominently increasing the printing productivity, allowing the use of thick ink that is quickly dried after printing, accomplishing the recent trend of compactness and smallness of the printing systems, and achieving

a clean and quick printing of a variety of vinyl products of any quantity.

Another aspect of the present invention to provide a method of controlling the operation of the vinyl printing system.

Additional aspects and/or advantages of the'invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

The above and/or other aspects are achieved by providing a vinyl printing system using a lithographic press, comprising: a first roll unit to unwind a vinyl sheet from a vinyl sheet roll to feed the vinyl sheet to a printing position of the vinyl printing system where the, vinyl sheet is printed; a lithographic press unit provided at the printed position of the vinyl printing system to unwind the vinyl sheet from the first roll unit while controlling a vinyl unwinding speed of the first roll unit and to print the vinyl sheet ; a second roll unit to wind the printed vinyl sheet fed from the lithographic press unit after printing ; a first speed sensing unit provided between the first roll unit and the lithographic press unit to sense the unwinding speed of the first roll unit while maintaining a tension of the vinyl sheet fed from the first roll unit to the lithographic press unit ; a second speed

sensing unit provided between the lithographic press unit and the second roll unit to sense a vinyl winding speed of the second roll unit while maintaining a tension of the printed vinyl sheet fed from the lithographic press unit to the second roll unit ; a control panel to allow an operator to control an operation of the vinyl printing system; and a control unit electrically connected to the control panel and a plurality of driving and sensing elements of the lithographic press unit, the first and second roll units, and the first and second speed sensing units, so that the control unit controls the operation of the plurality of driving elements in response to signals output from the variety of sensing elements.

The above and/or other aspects are achieved by providing a method of controlling the vinyl printing systems, comprising: a power-on step of power-on the vinyl printing system ; a drying unit start/mirror arranging step of operating a drying unit and placing a reflecting mirror on a shielding position, simultaneously with the powering-on of the vinyl printing system ; a pre-operation step of operating the system at a lower speed to achieve desired operational conditions of the system and monitor for any abnormal operation of the system ; a normal operation step of operating the system at a normal operational speed after confirming that the desired operational conditions of the system have been achieved

and the system has been operated in a normal state ; and an emergency stopping step of temporarily stopping the system when an emergency stopping button is operated in the case of occurrence of an operational error in the system during an operation of the system in a pre-operation mode or a normal operation mode.

BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which: FIG. 1 is a view of a vinyl printing system using a lithographic press, according to a first embodiment of the present invention; FIG. 2 is a plan view of the vinyl printing system of FIG. li FIG. 3 is a side view of each of first and second roll units which are a supply roll unit and a take-up roll unite, respectively, provided in the vinyl printing system of FIG. 1 to supply a vinyl sheet from a roll to a lithographic press unit and to wind the vinyl sheet on another roll after printing, during a vinyl printing process ;

FIG. 4 is a plan view of each of the first and second roll units of FIG. 3; FIG. 5 is a front view of each of the first and second roll units of FIG. 3; FIG. 6 is a view showing an assembled structure of a roll support shaft provided in each of the first and second roll units of FIG. 3 ; FIGS. 7a and 7b are sectional views respectively showing the construction and operation of the roll support shaft of FIG.

6; FIG. 8 is a front view of a vinyl-aligning roll unit included in the vinyl printing system of FIG. 1; FIG. 9 is a side view of the vinyl-aligning roll unit of FIG. 8 ; FIG. 10 is a rear view of each of first and second speed sensing units which are provided in the vinyl printing system of FIG. 1 to sense a vinyl unwinding speed and a vinyl winding speed, respectively; FIG. 11 is a plan view of each of the first and second speen sensing units of FIG. 10; FIG. 12 is a side view showing the operation of each of the first and second speed sensing units of FIG. 10 ;

FIG. 13 is a side view showing the construction of each of the first and second speed sensing units of FIG. 10; FIG. 14 is a side view of the lithographic press unit provided in the vinyl printing system of FIG. 1; FIG. 15 is a plan view of the lithographic press unit of FIG. 14; FIG. 16 is a front view of a first vinyl feeding unit provided in the lithographic press unit of FIG. 14; FIG. 17 is a side view of the first vinyl feeding unit of FIG. 16; FIGS. 18 and 19 are side sectional views respectively showing the construction and operation of a drying unit provided in the lithographic press unit of FIG. 14; FIG. 20 is a plan sectional view of the drying unit of FIG.

18 and 19; FIG. 21a and 21b are side views showing the operation of a reflecting mirror unit provided in the drying unit of FIGS. 18 and 19 ; FIG. 22 is a block diagram showing the construction of the vinyl printing system of FIG. 1, in which a plurality of elements of the system are connected to a control unit through a plurality of electric wires, so that the plurality of elements are operated

under the control of the control unit during a vinyl printing process; FIG. 23 and 24 are flowcharts of a controlmethod of controlling the operation of the vinyl printing system of FIG. 1; FIG. 25 is a view of a vinyl printing systemusing a lithographic press, according to a second embodiment of the present invention; FIG. 26 is a sectional view of a vinyl bag producing unit provided in the vinyl printing. system of FIG. 25 ; FIG. 27 is a block diagram showing the construction of the vinyl printing system of FIG. 25, in which a plurality of elements of the system are connected to a control unit through a plurality of electric wires, so that the plurality of elements are operated under the control of the control unit during a vinyl printing process; and FIG. 28 and29 are flowcharts of a controlmethodof controlling the operation of the vinyl printing system of FIG. 25.

BEST MODE FOR CARRYING OUT THE INVENTION Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like

reference numerals refer to like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.

FIG. 1 is a view of a vinyl printing system using a lithographic press, according to a first embodiment of the present invention. FIG. 2is a plan view. of the vinyl printing system of FIG. 1 FIG. 3 is a side view of each of first and secend roll units which are a supply roll unit and a take-up roll unit, respectively, provided in the vinyl printing system of FIG. 1 to supply a vinyl sheet from a roll to a lithographic press unit and to wind the vinyl sheet on another roll after printing, during a vinyl printing process. FIG. 4 is a plan view of each of the first and second roll units of FIG. 3. FIG. 5 is a front view of each of the first and second roll units of FIG. 3. FIG. 6 is a view showing an assembled structure of a roll support shaft provided in each of the first and second roll units of FIG. 3. FIG. 7a and 7b are sectional views respectively showing the construction and operation of the roll support shaft of FIG. 6. FIG. 8 is a front view of a vinyl-aligning roll unit included in the vinyl printing system of FIG. 1. FIG.

9 is a side view of the vinyl-aligning roll unit of FIG. 8. FIG.

10 is a rear view of each of first and second speed sensing units which are provided in the vinyl printing system of FIG. lto sense

a vinyl unwinding speed and a vinyl winding speed, respectively.

FIG. 11 is a plan view of each of the first and second speed sensing units of FIG. 10. FIG. 12 is a side view showing the operation of each of the first and second. speed sensing units of FIG. 10.

FIG. 13 is a side view showing the construction of each of the first and second speed sensing units of FIG. 10.. FIG. 14 is a side view of the lithographic press unit provided in the vinyl printing system of FIG. 1. FIG. 15 is a plan view of the lithographic press unit of FIG. 14. FIG. 16 is a front view of a first vinyl feeding unit provided in the lithographic press unit of FIG. 14. FIG. 17. is a side view of the first vinyl feeding unit of FIG. 14. FIGS.

18 and 19 are side sectional views respectively showing the construction and the operation of a drying unit provided in the lithographic press unit of FIG. 14.

FIG. 20 is a plan sectional view of the drying unit of FIGS. 18 and 19. FIGS. 21a and 21b are side views showing the operation of a reflecting mirror unit provided in the drying unit of FIGS.

18 and 19. FIG. 22 is a block diagram showing the construction of the vinyl printing system of FIG. 1, in which a plurality of elements of the system are connected to a control unit through a plurality of electric wires, so that the plurality of elements are operated under the control of the control unit during a vinyl

printing process. FIGS. 23 and 24 are flowcharts of a control method of controlling the operation of the vinyl printing system of FIG.

1.

As shown in FIG. 1 through 24, the vinyl printing system 10 using the lithographic press according to the first embodiment of the present invention quickly and precisely executes an automatic printing process of printing desired letters and/or figures on designated positions of a continued vinyl sheet 80 fed from a vinyl sheet roll. The vinyl printing system 10 according to the first embodiment comprises first and second roll units 11 and 18, a lithographic press unit 40, first and second speed sensing units 20 and 30 to respectively sense a vinyl unwinding speed and a vinyl winding speed, a control panel 50 and a control unit 60, as shown in FIGS. 1 through 22.

The first roll unit 11 is a supply roll unit to unwind the vinyl sheet 80 from a vinyl sheet roll to feed the vinyl sheet to the lithographic press unit 40, and comprises a support base part 12, a roll support part 13 and a roll support shaft part 14, as best seen in FIGS. 3 through 7b.

The support base part 12 is placed horizontally on and mounted to a support surface, thus supporting the roll support part 13 on the support surface while allowing the roll support

part 13 to move on the support base part 12. The support base part 12 comprises a support base 12a, a support column 12b and a plurality of guide rails 12f.

The support base 12a is a flat panel body which has a predetermined size and is installed horizontally on the support surface, with the plurality of rails 12f being arranged at predetermined positions of the upper surface of the support base 12a to be parallel to each other.

The support column 12b is a flat plate body which has a predetermined size and is vertically installed on a predetermined position of an end of the upper surface of the support base 12a, with a support hole 12c provided on the support column 12b an adjusting screw bar 12e assembled with the support column 12b.

The support hole 12c, having a predetermined diameter, is provided at a predetermined position on an upper portion of the support column 12b. The adjusting screwbar 12e is a longitudinal bar having a circular cross-section with a predetermined diameter and length, and comprises an externally threaded part 12d'which is provided within a predetermined range of a first end of the adjusting screwbar 12e andamanipulationpart 12dwhichisprovided on a second end of the adjusting screw bar 12e. The adjusting screw bar 12e is movably assembled with the support column 12b while

passing through the support hole 12c so that the manipulation part 12d projects outside the support hole 12c. In the above state, a bearing is interposed between the support hole 12c and the adjusting screw bar 12e to support a rotation of the screw bar 12e relative to the support column 12b.

The roll support part 13 comprises a roll support base 13a, a plurality of shaft support columns 13c and 13d, a drive unit 13i, a motor mount 13j and a first drive motor 13m. The roll support part 13 is installed on the support base part 12 to move along the plurality of guide rails 12f in conjunction with a reversible rotation of the adjusting screw bar 12e.

The roll support base 13a is a flat panel body which has a predetermined size, with a plurality of guide assemblies 13b provided at predetermined positions on a lower surface of the roll support base 13a to movably engage with the guide rails 12f of the support base part 12.

The plurality of shaft support columns 13c and 13d, each comprising a flat plate body which has a predetermined size, are vertically installed on predetermined positions of both ends of an upper surface of the roll support base 13a to be parallel to each other. A shaft bearing unit 13n is provided horizontally on the top end of each of the shaft support columns 13c and 13d provided

at both ends of the roll support base 13a, thus detachably supporting each end of the roll support shaft part 14.

The drive unit 13i comprises an adjusting screw hole 13e which is provided at a predetermined position on a lower portion of the first shaft support column 13c while having an internal thread to engage with the adjusting screw bar 12e of the support base part 12 through a screw-type engagement. The drive unit 13i further includes a drive shaft 13h, with a pulley 13f having a predetermined diameter and provided at a first end of the drive shaft 13h and a mounting hole 13g. The mounting hole 13g is formed by depressing the center of the second end of the drive shaft 13h to have a rectangular cross-section, thus being detachably assembled with an assembling part of the roll support shaft part 14. The drive unit 13i is installed at a predetermined position on the upper end of the second shaft support column 13d.

The motor mount 13j is installed horizontally on an end of the roll support base 13a on which the second shaft support column 13d is vertically installed. The first drive motor 13m is installed on the motor mount 13j, and has a pulley which is connected to the pulley 13f of the drive shaft 13h via a power transmission means 13k, such as a belt, thus driving the drive shaft 13h.

The roll support shaft part 14 comprises a longitudinal

roll support part 14a which has a circular cross-section and is provided at an intermediate portion of the roll support shaft part 14, with a plurality of roll support protrusions 14b provided at predetermined positions on the external surface of the roll support part 14a to be projected outside and retracted into the roller support part 14a by a pneumatic force. Both ends of the roll support shaft part 14 are rotatably and detachably supported by the shaft bearing units 13n of the first and second shaft support columns 13c and 13d, respectively, with a shaft bearing 14c interposed between each end of the roll support shaft part 14 and an associated one of the first and second shaft support columns 13c and 13d.

The roll support shaft part 14 further includes an axial mounting projection 14d is detachably assembled with the mounting hole 13g of the drive shaft 13h.

The second roll unit 18 is a take-up roll unit to wind the printed vinyl sheet, fed from the lithographic press unit 40, on an empty vinyl sheet roll, and comprises a support base part 16, a roll support part 17 and a roll support shaft part 19 in the same manner an that described for the first roll unit 11.

The support base part 16 is placed horizontally on and mounted to the support surface, thus supporting the roll support part 17 on the support surface while allowing the roll support

part 17 to move on the support base part 16. The support base part 16 comprises a support base 16a, a support column 16b and a plurality of guide rails 16f.

The support base 16a ia a flat panel body which has a predetermined size and is installed horizontally on the support surface, with the plurality of rails 16f being arranged on predetermined positions of the upper surface of the support base 16a to be parallel to each other.

The support column 16b is a flat plate body which has a predetermined size and is installed vertically on a predetermined position of an end of the upper surface of the support base 16a, with a support hole 16c provided on the support column 16b and an adjusting screw bar 16e assembled with the support column 16b.

The support hole 16c, having a predetermined diameter, is provided at a predetermined position on an upper portion of the support column 16b. The adjusting screw bar 16e is a longitudinal bar having a circular cross-section with a predetermined diameter and length, and comprises an externally threaded part 16d'which is provided within a predetermined range of a first end of the adjusting screwbar 16e andamanipulationpart l6dwhich is provided on a second end of the adjusting screw bar 16e. The adjusting screw bar 16e is movably assembled with the support column 16b while

passing through the support hole 16c so that the manipulation part 16d projects outside the support hole 16c. In the above state, a bearing is interposed between the support hole 16c and the adjusting screw bar 16e to support a rotation of the screw bar 16e relative to the support column 16b.

The roll support part 17 comprises a roll support base 17a, a plurality of shaft support columns 17c and 17d, a drive unit 17i, a motor mount 17j and a second drive motor 17m. The roll support part 17 is installed on the support base part 16 to move along the plurality of guide rails 16f in conjunction with a reversible rotation of the adjusting screw bar 16e.

The roll support base 17a is a flat panel body which has a predetermined size, with a plurality of guide assemblies 17b provided at predetermined positions on a lower surface of the roll support base 17a to movably engage with the guide rails 16f of the support base part 16.

The plurality of shaft support columns 17c and 17d, each comprising a flat plate body which has a predetermined size, are vertically installed on predetermined positions of both ends of an upper surface of the roll support base 17a to be parallel to each other. A shaft bearing unit 17n is provided horizontally on the top end of each of the shaft support columns 17c and 17d provided

at both ends of the roll support base 17a, thus detachably supporting each end of the roll support shaft part 19.

The drive unit 17i comprises an adjusting screw hole 17e which is provided at a predetermined position on a lower portion of the first shaft support column 17c while having an internal thread to engage with the adjusting screw bar 16e of the support base part 16 through a screw-type engagement. The drive unit 17i further includes a drive shaft 17h, with a pulley 17f having a predetermined diameter and provided at a first end of the drive shaft 17h and a mounting hole 17g procided at a center of a second end of the drive shaft 17h. The mounting hole 17g is formed by depressing the center of the second end of the drive shaft 17h to have a rectangular cross-section, thus'being detachably assembled with an assembling part of the roll support shaft 19.

The drive unit 17i is installed at a predetermined position on the upper end of the second shaft shpport column 17d.

The motor mount 17j is installed horizontally on an end of the roll support base 17a on which the second shaft support column 17d is vertically installed. The second drive motor 17m is installed on the motor 17j, and has a pulley which is connected to the pulley 17f of the drive shaft 17h via a power transmission means 17k, such as a belt, thus driving the drive shaft 17h.

The roll support shaft part 19 comprises a longitudinal roll support part 19a which has a circular cross-section and is provided at an intermediate portion of the roll support shaft part 19, with a plurality of roll support protrusions 19b provided at predetermined positions on the external surface of the roll support part 19a to be projected outside and retracted into the roller support part 19a by a pneumatic force. Both ends of the roll support shaft part 19 are rotatably and detachably supported by the shaft bearing units 17n of the first and second shaft support columns 17c and 17d, respectively, with a shaft bearing 19c interposed between each end of the roll support shaft part 19 and an associated one of the first and second shaft support columns 17c and 17d. The roll support shaft part 19 further includes an axial mounting projection 19d at an end thereof, so that the axial mounting projection 19d is detachably assembled with the mounting hole 17g of the drive shaft 17h.

The lithographic press unit 40 unwinds the vinyl sheet 80 from the first roll unit 11 while controlling a vinyl unwinding speed of the first roll unit 11 and to print desired letters and/or figures on the vinyl sheet 80. The lithographic press unit 40 comprises a main frame 41, a vinyl-aligning roll unit 42, a lithographic press 43, a drying unit 44, a first vinyl feeding

unit 45 and a tension roller 46, as shown in FIGS. 14 and 15.

As shown in FIGS. 14 and 15, the main frame 41 of the lithographic press unit 40 is a box-shaped body having a predetermined size. The vinyl-aligning roll unit 42 is installed on a first end of an upper surface of the main frame 41 to align the vinyl sheet 80, which is fed from the first roll unit 11, with a printing position of the'lithographic press 43. The vinyl-aligning roll unit 42 comprises a support roller 42a which is placed horizontally at a lower position in the roll unit 42 to be rotated around its rotating axis, and a movable roller 42b which is horizontally placed at an upper position above the support roller 42a in the roll unit 42 to be rotated around its rotating axis and to be movable in a vertical direction to adjust a gap between the two rollers 42a and 42b, as best seen in FIGS. 8 and 9.

The lithographic press 43 is installed on the upper surface of the main frame 41 at a predetermined position spaced apart from the vinyl-aligning roll unit 42 by a predetermined distance, as shown in FIGS. 14 and 15, and prints desired letters and/or figures on the vinyl sheet 80 which is fed from the vinyl-aligning roll unit 42. The lithographic press 43 is operated by a lithographic press drive motor 43a.

The drying unit 44 is installed on a lower surface of the main frame 41 at a predetermined position to dry the printed vinyl sheet 80 fed from the lithographic press 43. The drying unit 44 comprises a casing 44a, a UV housing 44g, a blower fan 44h, a UV lamp 44i, a reflecting mirror 44j and a mirror drive motor 44k, as shown in FIGS, 18 through 20.

The casing 44a of the drying unit 44 is a box-shaped body which is hollow and opened at an end thereof, with a door 44b hinged to a lower edge of the opened end of the casing 44a to open or close the opened end. A vinyl inlet slit 44c is provided on the upper surface of the casing 44a at a predetermined posit ion adjacent to the opened end to introduce the printed vinyl sheet 80 into the casing 44a. A vinyl outlet slit 44d is provided on the lower surface of the casing 44a to correspond to the vinyl inlet slit 44c, thus discharging the printed vinyl sheet 80 from the casing 44a. A metal-plated rod 44e having a predetermined diameter and length is arranged along a first longitudinal edge of each of the vinyl inlet slit 44c and the vinyl outlet slit 44d at a position outside the casing 44a to guide the printed vinyl sheet 80 which is fed into or discharged from the casing 44a through each of the vinyl inlet slit 44c and the vinyl outlet slit 44d, without damaging the surface of the vinyl sheet 80. A light visor 44f is arranged

along a second longitudinal edge of each of the vinyl inlet slit 44c and the vinyl outlet slit 44d at a position opposite to the metal-plated rod 44e, thus preventing light from penetrating through the casing 44a via each of the vinyl inlet slit 44c and the vinyl outlet slit 44d.

The UV housing 44g is a box-shaped body which is opened at an end thereof and is installed in the casing 44a to move forward and rearward relative to the casing 44a within a predetermined moving range.

The blower fan 44h is installed in a fan chamber provided on an end of the UV housing 44g. Since the fan chamber having the fan 44h communicates with the interior of the UV housing 44g, the fan 44h discharges hot air, which is caused by UV (ultraviolet) lays emitted from the UV lamp 44i, from the interior to the outside of the UV housing 44g.

The UV lamp 44i is installed in the UV housing 44g to emit the ultraviolet rays.

As best seen in FIGS. 21a and 21b, the reflecting mirror 44j having a semicircular cross-section is installed in the UV housing 44g to cover the UV lamp 44i. The reflecting mirror 44j is rotated around the UV lamp 44i at an angle of 180.

The mirror drive motor 44k is rotated in opposite

directions under the control of the control unit 60 to rotate the reflectingmirror44jattheangleof180. Inthepresentinvention, an SPG motor (shaded pole induction geared motor) is preferably used as the mirror drive motor 44k.

The first vinyl feeding unit 45 is installed on a second end of a bottom of the main frame 41 to pull the printed vinyl sheet 80 from the drying unit 44 in a predetermined pattern, thus feeding the printed vinyl sheet 80 from the drying unit 44. The first vinyl feeding unit 45 comprises a drive roller 45a, an idle roller 45b and roller drive motor 45d, as shown in FIGS. 14, through 17.

The drive roller 45a of the first vinyl feeding unit 45 is provided at an end thereof with a pulley 4 5c having a predetermined diameter, and is horizontally installed at a lower position in the first vinyl feeding unit 45 to be rotated around its rotating axis. The idle roller 45b is horizontally installed at an upper position above the drive roller 45a to be rotated around its rotating axis and to be movable vertically. The roller drive motor 45d has a pulley which is connected to a pulley of the drive roller 45a via a power transmission means 45c, such as a belt, thus driving the drive roller 45a. In the present invention, a servo-motor is preferably used as the roller drive motor 45d.

The tension roller 46 is horizontally installed on a position of the bottom of the main frame 41 between the drying unit 44 and the first vinyl feeding unit 45 to be rotated, thus tensioning the printed vinyl sheet 80 fed from the drying unit to the first vinyl feeding unit 45.

The first speed sensing unit 20 is installed between the first roll unit 11 and the lithographic press unit 40, and senses the vinyl unwinding speed of the first roll unit 11 while maintaining a predetermined tension of the vinyl sheet 80 which is fed from the first roll unit 11 to the lithographic press unit 40. The first speed sensing unit 20comprises a main frame 21, an arm support shaft 22, a pair of arms 23, a gear 24, a first angle detector 25 and a tension roller 26, as shown in FIGS. 10 through 13.

The main frame 21 of the first speed sensing unit 20 comprises a frame body having a predetermined height and width, with two shaft support holes 21a provided. on predetermined positions of both sides of the main frame 21.

The arm support shaft 22 is a longitudinal shaft having a predetermined length, and is supported at both ends thereof by the shaft support holes 21a of the main frame 21 to be rotated.

The pair of arms 23, each comprising a longitudinal rod having a predetermined length, are mounted at inside ends thereof

to both ends of the arm support shaft 22 to be perpendicular to the arm support shaft 22 and to be parallel to each other. The outside ends of the pair of arms 23 are connected to each other by a roller 23a. In the above state, the roller 23a is perpendicularly coupled at both ends thereof to the outside ends of the arms 23 to be rotated.

The gear 24 is provided at an end of the arm support shaft 22 to be rotated in conjunction with the arm support shaft 22.

The first angle detector 25 engages with the gear 24 through a gearing engagement to detect a rotated angle of the arms 23.

The tension roller 26 is rotatably installed on the upper surface of the main frame 21 to support the vinyl sheet 80 while the vinyl sheet 80 is fed from the first roll unit 11 to the lithographic press unit 40.

The second speed sensing unit 30 is installed between the lithographic press unit 40 and the second roll unit 18, and senses the vinyl winding speed of the second roll unit 18 while maintaining a predetermined tension of the printed vinyl sheet 80 which is fed from the lithographic press unit 40 to the second roll unit 18. The second speed sensing unit 30 comprises a main frame 31, an arm support shaft 32, a pair of arms 33, a fear 34, a second angle detector 35 and a tension roller 36, in the same

manner as that described for the first speed sensing unit 20 as shown in FIGS. 10 through 13.

The main frame 31 of the second speed sensing unit 30 comprises a frame bot having a predetermined height and width, with two shaft support holes 31a provided on predetermined positions of both sides of the main frame 31.

The arm support shaft 32 is a longitudinal shaft having a predetermined length, and is supported at both ends thereof by the shaft support holes 31a of the main frame 31 to be rotated.

The pair of arms 33, each comprising a longitudinal rod having a predetermined length, are mounted on inside ends thereof to both ends of the arm support shaft 32 to be perpendicular to the arm support shaft 32 and to be parallel to each other. The outside ends of the pair of arms 33 are connected to each other byaroller33a. Intheabovestate, theroller33aisperpendicularly coupled at both ends thereof to the outside ends of the arms 33 to be rotated.

The gear 34 is provided on an end of the arm support shaft 32 to be rotated in conjunction with the arm support shaft 32.

The second angle detector 35 engages with the gear 34 through a gearing engagement to detect a rotated angle of the arms 33. The tension roller 36 is rotatably installed on the upper surface

of the main frame 31 to support the printed vinyl sheet 80 while the printed vinyl sheet 80 is fed from the lithographic press unit 40 to the second roll unit 18.

The control panel 50 which comprises a plurality of control levers and control switches to be used for controlling the system 10, is connected to the control unit 60 through an electric wire, as shown in FIG. 22, thus allowing an operator to turn the vinyl printing system 10 on or off, as. well as maintain and repair the system 10. The control panel 50 also allows the operator to stop the operation of the system 10 in the case of occurrence of an abnormal state.

The control unit 60 is a microcomputer which is electrically connected to the control panel 50 and the variety of driving and sensing elements of the lithographic press unit 40, the first and second roll units 11 and 18, and the first and second speed sensing units 20 and 30, so that the control unit 60 controls the operation of the variety of driving elements in response to signals output from the variety of sensing elements.

Herein below, the control method of controlling the operation of the vinyl printing system 10 using the lithographic press according to the first embodiment of the present invention will be described.

The operation of the vinyl printing system 10 using the lithographic press according to the first embodiment of the present invention is controlled as follows. In response to manipulation signals output from the control panel 50 which is manipulated by the operator, the control unit 60 of the system 10 executes a power-on step s100, a drying unit start/mirror arranging step s110, a pre-operation step sl20, a normal operation step s130 and an emergency stopping step s140, as sho r-in FIGS. 23 and 24.

As shown in FIG. 23, at the power-on step s100, electric power is supplied to the vinyl printing system 10 in response to a manipulation of the operator who turns on a power switch of the control panel 50. At the same time, the drying unit start/mirror arranging step s110 is executed.

At the drying unit start/mirror arranging step s110, the drying unit 44 is operated simultaneously with the power-on of the system 10, so that both the UV lamp 44i and the blower fan 44h of the drying unit 44 are operated. Thus, the UV lamp 44i emits ultraviolet rays, and thus generates heat. In the above state, to protect a part of the vinyl sheet 80 placed between the vinyl inlet slit 44c and the vinyl outlet slit 44d of the drying unit 44 from being damaged by heat generated from the UV lamp 44i, the rotating shaft of the mirror drive motor 44k is rotated at an angle

of 180'in a predetermined direction, thus rotating the reflecting mirror 44j to the same angle in the same direction and thereby shielding the vinyl sheet 80 from the heat of the UV lamp 44i.

To execute the pre-operation step s120, the operator manipulates a mode control lever of the control panel 50 to a pre-operation mode of the system 10. At the pre-operation step s120, the system 10 is operated at a lower speed, so that desired operational conditions of the system 10 can be achieved and, at the same time, the operator can monitor for any abnormal operation of the system 10. The pre-operation step 120 comprises a low-speed operating step s121, a vinyl unwinding speed checking step s122, a vinyl unwinding speed adjusting step sl23, a vinyl winding speed checking step s124, a vinyl winding speed adjusting step sl25, a variable roller gap checking step s126, a vinyl feeding unit high-speed operating step s127, and a vinyl feeding unit normal operating step s128.

The low-speed operating step s121 is executed in response to the manipulation of the mode control lever of the control panel 50 to the pre-operation mode of the system 10. At the low-speed operating step s121, the control unit 60 operates the first and second roll units 11 and 18, the first vinyl feeding unit 45 and the lithographic press 43 at low speeds.

At the vinyl unwinding speed checking step s122, the control unit 60 determines whether the rotated angle of the arms 23 of the first speed sensing unit 20 is significantly higher or lower than a first predetermined reference angle.

At the vinyl unwinding speed adjusting step s123, the control unit 60 reduces the operational speed of the first roll unit 11 when the rotated angle of the arms 23 of the first speed sensing unit 20 has been determined at the inquiry step s122 to be lower than the first predetermined reference angle. However, the control unit 60 at the vinyl unwinding speed adjusting step s123 increases the operational speed of the first roll unit 11 when the rotated angle of the arms 23 of the first speed sensing unit 20 has been determined at the inquiry step s122 to be higher than the first predetermined reference angle. Thus, the feeding speed of the vinyl sheet 80 which is fed from the first roll unit 11 to the lithographic press unit 40 is maintained at an appropriate speed.

At the vinyl speed checking step s124, the control unit 60 determines whether the rotated angle of the arms 33 of the second speed sensing unit 30 is significantly higher or lower than a second predetermined reference angle.

At the vinyl winding speed adjusting step s125, the control

unit 60 increases the operational speed of the second roll unit 18 when the rotated angle of the arms 33 of the second speed sensing unit 30 has been determined at the inquiry step s124 to be lower than the secondpredetermined reference angle. However, the control unit 60 at the vinyl winding speed adjusting step s125 reduces the operational speed of the second roll unit 18 when the rotated angle of the arms 33 of the second speed sensing unit 30 has been determined to be higher than the second predetermined reference angle. Thus, the vinyl winding speed of the second roll unit 18 to wind the printed vinyl sheet 80 thereon is maintained at an appropriate speed.

At the variable roller gap checking step s126, the control unit 60 determines whether a variable roller is spaced apart from a blanket roller of the lithographic press 43.

The vinyl feeding unit high-speed operating step s127 is executed when the answer of the inquiry step s126 is"YES".

At the vinyl feeding unit high-speed operating step s127, the control unit 60 operates the first vinyl feeding unit 45 at a predetermined higher speed to increase the vinyl feeding speed to a predetermined feeding speed. Thus, a next printed position of the vinyl sheet 80 is precisely aligned with the printing start position of the blanket roller of the lithographic press 43

However, when the answer of the inquiry step sl26 is"NO", the vinyl feeding unit normal operating step s128 is executed.

At the vinyl feeding unit normal operating step s128, the control unit 60 operates the first vinyl feeding unit 45 at the same speed as the operating speed of the lithographic press 43.

The normal operation step s130 is executed in response to a manipulation of the operator who manipulates the mode control lever of the control panel 50 to a normal operation mode of the system 10 after confirming that the desired operational conditions of the system 10 have been achieved and the system 10 has been operated in a normal state. At the normal operation step s130, the operational speed of the system 10 is increased to allow the system 10 to be operated at a normal operational speed. As shown in FIG. 24, the normal operation step s130 comprises a high-speed operating step s131, a vinyl unwinding speed checking step s132, a vinyl unwinding speed adjusting step s133, a vinyl winding speed checking step s134, a vinyl winding speed adjusting step s135, a variable roller gab checking step s136, a vinyl feeding unit high-speed operating step s137, and a vinyl feeding unit normal operating step s138.

The high-speed operating step s131 is executed in response to a manipulation signal output from the mode control lever of

the control panel 50 which is manipulated to the normal operation mode of the system 10. At the high-speed operating step s131, the control unit 60 operates the first and second roll units 11 and 18, the first vinyl feeding unit 45 and the lithographic press 43 at high speeds.

At the vinyl unwinding speed checking step s132, the control unit 60 determines whether the rotated angle of the arms 23 of the first speed sensing unit 20 is significantly higher or lower than third predetermined reference angle.

At the vinyl unwinding speed adjusting step s133, the control unit 60reduces the operational speed of the first roll unit 11 when the rotated angle of the arms 23 of the first speed sensing unit 20 has been determined at the inquiry step s132 to be lower than the third predetermined reference angle. However, the control unit 60 at the vinyl unwinding speed adjusting step s133 increases the operational speed of the first roll unit 11 when the rotated angle of the arms 23 of the first speed sensing unit 20 has been determined at the inquiry step s132 to be higher than the third predetermined reference angle, Thus, the feeding speed of the vinyl sheet 80 which is fed from the first roll unit 11 to the lithographic press unit 40 is maintained at an appropriate speed.

At the vinyl winding speed checking step s134, the control unit 60 determines whether the rotated angle of the arms 33 of the second speed sensing unit 30 is significantly higher or lower than a fourth predetermined reference angle.

At the vinyl winding speed adjusting step s135, the control unit 60 increases the operational speed of the second roll unit 18 when the rotated angle of the arms 33 of the second speed sensing unit 30 has been determined at the inquiry step s134 to be lower than the fourth predetermined reference angle. However, the control unit 60 at the vinyl winding speed adjusting step s135 reduces the operational speed of the second roll unit 18 when the rotated angle of the arms 33 of the second speed sensing unit 30 has been determined to be higher than the fourth predetermined reference angle. Thus, the vinyl winding speed of the second roll unit 18 to wind the printed vinyl sheet 80 thereon is maintained at an appropriate speed.

At the variable roller gap checking step s136, the control unit 60 determines whether the variable roller is spaced apart from the blanket roller of the lithographic press 43.

The vinyl feeding unit high-speed operating step s137 is executed when the answer of the inquiry step s136 is"YES".

At the vinyl feeding unit high-speed operating step s137, the

control unit 60 operates the first vinyl feeding unit 45 at a predetermined higher speed to increase te vinyl feeding speed to a predetermined feeding speed. Thus, a next printed position of the vinyl sheet 80 is precisely aligned with the printing start position of the blanket roller of the lithographic press 43.

However, when the answer of the inquiry step sl36 is"NO", the vinyl feeding unit normal operating step s138 is executed.

At the vinyl feeding unit normal operating step s138, the control unit 60 operates the first vinyl feeding unit 45 at the same speed as the operating speed of the lithographic press 43.

The emergency stopping step s140is executed in response to a manipulation signal output from an emergency stopping button provided on the control panel 50 or on a predetermined position of the system 10 when there occurs an operational error while the system 10 is operated in the pre-operation mode or the normal operation mode. At the emergency stopping step s140, the operation of the system 10 is temporarily stopped.

FIG. 25 is a view of a vinyl printing system using a lithographic press, according to a second embodiment of the present invention. FIG. 26 is a sectional view of a vinyl bag producing unit provided in the vinyl printing system of FIG. 25. FIG. 27 is a block diagram showing the construction of the vinyl printing

system of FIG. 25, in which a plurality of elements of the system are connected to a control unit through a plurality of electric wires, so that the plurality of elements are operated under the control of the control unit during a vinyl printing process. FIGS.

28 and 29 are flowcharts of a control method of controlling the operation of the vinyl printing system of FIG. 25.

As shown in FIGS. 25 through 29, the vinyl printing system 10 using the lithographic press according to the second embodiment of the present invention produces a plurality of printed vinyl bags using the printed vinyl sheet 80 just after printing desired letters and/or figures on the vinyl sheet 80, in place of winding the printed vinyl sheet 80 around the second roll unit, different from the vinyl printing system according to the first embodiment of the present invention. To produce the printed vinyl bags, the vinyl printing system 10 according to the second embodiment of the present invention comprises a first roll unit 11, a vinyl bag producing unit 70, a lithographic press unit 40, first and second speed sensing units 20 and 30 to respectively sense a vinyl unwinding speed and a vinyl winding speed, a control panel 50 and a control unit 60, as shown in FIGS. 25 through 27. In a brief description of the construction of the vinyl printing system 10 according to the second embodiment, the second roll unit 80 of the first

embodiment is removed from the system 10, while the vinyl bag producing unit 70 is installed on the position from which the second roll unit 18 is removed. Thus, the vinyl bag producing unit 70 produces a plurality of printed vinyl bags using the printed vinyl sheet 80 which is fed from the lithographic press unit 40.

The vinyl bag producing unit 70 to produce the plurality of printed vinyl bags using the printed vinyl sheet 80 fed from the lithographic press unit 40 comprises an vinyl-aligning roll unit 71, first and second tension rollers 72 and 73, a vinyl bag length adhusting roller 74, a heat seaming iron unit 75, a second vinyl feeding unit 76 and a cutter 77. The vinyl bag producing unit 70 is installed in the system 10 to be spaced apart from the second speed sensing unit 30 by a predetermined distance.

The vinyl-aligning roll unit 71 is provided at an inlet of the vinyl bag producing unit 70 to align the printed vinyl sheet 80 fed from the second speed sensing unit 30 to the vinyl bag producing unit 70. The tension rollers 72 and 73 are horizontally and rotatably arranged in the vinyl bag producing unit 70 to be spaced apart from the vinyl-aligning roll unit 71 by predetermined distances while being parallel to the vinyl-aligning roll unit 71 and to each other.

The vinyl bag length adjusting roller 74 is horizontally

and rotatably arranged in the vinyl bag producing unit 70 at a position between the tension rollers 72 and 73 to be parallel to the tension rollers 72 and 73. The vinyl bag length adjusting roller 74 is movable in a vertical direction to adjust a vertical position thereof. Since the distance between the heat seaming iron unit 75 and the cutter 77 is fixed and both the heat seaming iron unit 75 and the cutter 77 are operated synchronously, the vinyl bag producing unit 70 may fail to produce vinyl bags having a variety of lengths. However, since the vinyl bag producing unit 70 of the second embodiment has the vinyl bag length adjusting roller 74 between the heat seaming iron unit 75 and the cutter 77, the operator can adjust the vertical position of the vinyl bag length adjusting roller 74 to variously control the length of a part of the printed vinyl sheet 80 placed between the heat seaming iron unit 75 and the cutter 77. Thus, the vinyl bag producing unit 70 can produce vinyl bags having a variety of lengths, as desired.

The heat seaming iron unit 75 is installed between the vinyl-aligning roll unit 71 and the first tension roller 72, and comprises a heat seaming iron which is movable in a vertical direction to thermally seam the printed vinyl sheet 80 at designated positions to produce the vinyl bags, with a single seaming line or double seaming lines formed at every seamed end of vinyl bags.

The cutter 77 is installed at a position in the vinyl bag producing unit 70 which is spaced apart from an outlet of the second vinyl feeding unit 76, thus cutting the seamed printed vinyl sheet 80 into the vinyl bags. In the above state, the cutter 77 cuts the seamed printed vinyl sheet 80 along a latitudinal linear cutting line or along a 2-shaped cutting line to produce each of the vinyl bags. In a detailed description, when the heat seaming iron unit 75 thermally seams the printed vinyl sheet 80 slong a single seaming line, the cutter 77 cuts the seamed printed vinyl sheet 80 along a latitudinal linear cutting line in back of the single seaming line, thus producing a vinyl bag without having a handle.

However, when the heat seaming iron unit 75 thermally seams the printed vinyl sheet 80 along double seaming lines spaced apart from each other at a predetermined interval, the cutter 77 cuts <BR> <BR> the seamed printed vinyl sheet 8 0 along a latitudinal linear cutting line between the double seaming lines and forms a plurality of U-shaped cut lines along a rear seaming line, thus producing a vinyl bag having handles.

The second vinyl feeding unit 76 is horizontally installed between the second tension roller 73 and the cutter 75 to feed the seamed printed vinyl sheet 80 from the second tension roller 73 to the cutter 75.

Furthermore, the second vinyl feeding unit 76 is operated by a third drive motor 76a in conjunction with the first vinyl feeding unit 45 of the lithographic press unit 40. Both the heat seaming iron unit 75 and the cutter 77 are operated in conjunction with the drive motor 43a of the lithographic press 43.

Herein below, the control method of controlling the operation of the vinyl printing system 10 using the lithographic press according to the second embodiment of the present invention will be described.

The operation of the vinyl printing system 10 using the lithographic press according to the second embodiment of the present invention is controlled as follows. In response to manipulation signals output from the control panel 50 which is manipulated by the operator, the control unit 60 of the system 10 executes a power-on step s200, a drying unit start/mirror <BR> <BR> arranging step s210, a pre-operation step s220, a normal operation step s230 and an emergency stopping step s240, as shown in FIGS.

28 and 29.

As shown in FIG. 28, at the power-on step s200, electric power is supplied to the vinyl printing system 10 in response to a manipulation of the operator who turns on the power switch of thecontrolpanel50. Atthesametime, thedryingunitstart/mirror

arranging step s210 is executed.

At the drying unit start/mirror arranging step s210, the drying unit 44 is operated simultaneously with the power-on of the system 10, so that both the UV lamp 44i and the bower fan 44h of the drying unit 44 are operated. Thus, the UV lamp 44i emits ultraviolet rays, and thus generates heat. In the above state, to protect a part of the vinyl sheet 80 placed between the vinyl inlet slit 44c and the vinyl outlet slit 44d of the drying unit 44 from being damaged by heat generated from the UV lamp 44i, the <BR> <BR> rotating shaft of the mirror drive motor 44k is rotated at an angle of inapredetermineddirection, thusrotatingthereflecting mirror 44j to the same angle in the same direction and thereby shielding the vinyl sheet 80 from the heat of the UV lamp 44i.

To execute the pre-operation step s220, the operator manipulates the mode control lever of the control panel 50 to the pre-operation mode of the system 10. At the pre-operation step s220, the system 10 is operated at a lower speed, so theat desired operational conditions of the system 10 can be achieved and, at the same time, the operator can monitor for any abnormal operation of the system 10. The pre-operation step 220 comprises a low-speed operating step s221, a vinyl unwinding speed checking step s222, a vinyl unwinding speed adjusting step s223, a variable roller

gab checking step s224, a vinyl feeding unit high-speed operating step s225, a vinyl feeding unit normal operating step s226, a variable roller contact checking step s227 and an iron unit/cutter operating step s228.

The low-speed operating step s221 is executed in response to the manipulation of the mode control lever of the control panel 50 to the pre-operation mode of the systemic. At the low-speed operating step s221, the control unit 60 operates the first roll unit 11, the first and second vinyl feeding units 45 and 76, the lithographic press 43, the heat seaming iron unit 75 and the cutter 77 at low speeds. Furthermore, the control unit 60 rotates the reflectingmirror 44j of the dryingunit 44 to a reflectingposition.

At the vinyl unwinding speed checking step s222, the control unit 60 determines whether the rotated angle of the arms 23 of the first speed sensing unit 20 is significantly higher or lower than a fifth predetermined reference angle.

At the vinyl unwinding speed adjusting step s223, the control unit 60 reduces the operational speed of the first roll unit 11 when the rotated angle of the arms 23 of the first speed sensing unit 20 has been determined at the inquiry step s222 to be lower than the fifth predetermined reference angle. However, the control unit 60 at the vinyl unwinding speed adjusting step

s223 increases the operational speed of the first roll unit 11 when the rotated angle of the arms 23 of the first speed sensing unit 20 has been determined at the inquiry step s222 to be higher than the fifth predetermined reference angle. Thus, the feeding speed of the vinyl sheet 80 which is fed from the first roll unit 11 to the lithographic press unit 40 is maintained at an appropriate speed.

At the variable roller gap checking step s224, the control unit 60 determines whether the variable roller is spaced apart from the blanket roller of the lithographic press 43.

The vinyl feeding unit high-speed operating step s225 is executed when the answer of the inquiry step s224 is"YES".

At the vinyl feeding unit high speed operating step s225, the control unit 60 operates the first and second vinyl feeding units 45 and 76 at a predetermined higher speed to increase the vinyl feeding speed to a predetermined feeding speed. Thus, a next printed <BR> <BR> positionof the vinyl sheet 80 ispreciselyalignedwith the printing start position of the blanket roller of the lithographic press 43.

However, when the answer of the inquiry step s224 is"NO", the vinyl feeding unit normal operating step s226 is executed.

At the vinyl feeding unit normal operating step s228, the control

unit 60 operates the first and second vinyl feeding units 45 and 76 at the same speed as the operating speed of the lithographic press 43.

At the variable roller contact checking step s227, the control unit 60 determines whether the variable roller is in contact with the blanket roller of the lithographic press 43.

When the answer of the inquiry step s227 is"YES", the iron unit/cutter operating step s228 is executed to operate both the heat seaming iron unit 75 and the cutter 77 of the vinyl bag producing unit 70, thus thermally seaming and cutting the printed vinyl sheet 80 to produce printed vinyl bags.

The normal operation step s230 is executed in response to a manipulation of the operator who manipulates the mode control lever of the control panel 50 to the normal operation mode of the system 10 after confirming that the desired operational conditions of the system 10 have been achieved and the system 10 has been operated in a normal state. At the normal operation step s230, the operational speed of the system 10 is increased to allow the system 10 to be operated at a normal operational speed. As shown in FIG. 29, the normal operation step s230 comprise a high-speed operating step s231, a vinyl unwinding speed checking step s232, a vinyl unwinding speed adjusting step s233, a variable roller

gap checking step s234, a vinyl feeding unit high-speed operating step s235, a vinyl feeding unit normal operating step s236, a <BR> <BR> variable roller contact checking step s237, and an iron unit/cutter operating step s238.

The high-speed operating step s231 is executed in response to a manipulation signal output from the mode control lever of the control panel 50 which is manipulated to the normal operation mode of the system 10. At the high-speed operating step s231, the control unit 60 operates the first roll unit 11, the first and second vinyl feeding units 45 and 76, the lithographic press 43, the heat seaming iron unit 75 and the cutter 77 at high speeds.

At the vinyl unwinding speed checking step s232, the cintrol unit 60 determined whether the rotated angle of the arms 23 of the first speed sensing unit 20 is significantly higher or lower than a sixth predetermined reference angle.

At the vinyl unwinding speed adjusting step s233, the control unit 60 reduce the operational speed of the first roll unit 11 when the rotated angle of the arms 23 of the first speed sensing unit 20 has been determined at the inquiry step s232 to be lower than the sixth predetermined reference angle. However, th control unit 60 at the vinyl unwinding speed adjusting step s233 increases the operational speed of the first roll unit 11

when the rotated angle of the arms 23 of the first speed sensing unit 20 has been determined at the inquiry step s232 to be higher than the sixth predetermined reference angle. Thus, the feeding speed of the vinyl sheet 80 which is fed from the first roll unit 11 to the lithographic press unit 40 is maintained at an appropriate speed.

At the variable roller gap checking step s234, the control unit 60 determines whether the variable roller is spaced apart from the blanket roller of the lithographic press 43.

The vinyl feeding unit high-speed operating step s235 is executed when the answer of the inquiry step s234 is"YES".

At the vinyl feeding unit high-speed operating step s235, the control unit 60 operates the first and second vinyl feeding units 45 and 76 at a predetermined higher speed to increase the vinyl feeding speed to a predetermined feeding speed. Thus, a next printed position of the vinyl sheet 8 0 is precisely aligned with the printing start position of the blanket roller of the lithographic press 43.

However, when the answer of the inquiry step s234 is"NO", the vinyl feeding unit normal operating step s236 is executed.

At the vinyl feeding unit normal operating step s236, the control unit 60 operates the first and second vinyl feeding units 45 and

76 at the same speed as the operating speed of the lithographic press 43.

At the variable roller contact checking step s237, the control unit 60 determines whether the variable roller is in contact with the blanket roller of the lithographic press 43.

When the answer of the. inquiry step s237 is"YES", the iron unit/cutter operating step s238 is executed to operate both the heat seaming iron unit 75 and the cutter 77 of the vinyl bag producing unit 70, thus thermally seaming and cutting the printed vinyl sheet 80 to produce printed vinyl bags.

The emergency stopping step s240 is executed in response to a manipulation signal output from an emergency stopping button provided on the control panel 50 or on a predetermined position of the system 10 when there occurs an operational error while the system 10 is operated in the pre-operation mode or the normal operation mode. At the emergency stopping step s240, the operation of the system 10 is temporarily stopped.

INDUSTRIAL APPLICABILITY As apparent from the above description, the present invention provides a vinyl printing system using a lithographic press, and

a method of controlling the operation of the vinyl printing system.

During the operation of the vinyl printing system, the feeding speed of vinyl sheet unwound from or wound around a roll is automatically controlled in response to a printing speed and the tension of the vinyl sheet is maintained at a constant tension.

Therefore, the vinyl printing system quickly and precisely prints desired letters and/or figures on the vinyl sheet, and provides the clearly-printed vinyl sheet. Thus, the vinyl printing system remarkably reduces printing costs, prominently increases the printing productivity, allows the use of thick ink that is quickly dried after printing, accomplishes the recent trend of compactness and smallness of the printing systems, and achieves a clean and quick printing of a variety of vinyl products in small and large quantities.

Although a few preferred embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.