WO2008143366A1

WO2008143366A1 - Radio frequency identification printer

Info

Publication number: WO2008143366A1
Application number: PCT/KR2007/002409
Authority: WO
Inventors: Ki Chul Moon; Hyung Hee Han; Jong Keun Choi; Jang Woon Jeong
Original assignee: Sewoo Tech Co., Ltd.
Priority date: 2007-05-17
Filing date: 2007-05-17
Publication date: 2008-11-27

Abstract

The present invention provides an RFID printer, which has a ribbon roll and RFID tag roll detecting function, a ribbon wrinkling prevention function, a thermal head overheating prevention function and an RFID data collision prevention function. The RFID printer includes a printer unit (100), which has an RFID tag roll detecting bar (121), an RFID tag roll switch (122) disposed adjacent to the RFID tag roll detecting bar to create an RFID tag roll replacement signal, a ribbon module having two ribbon rollers to control movement of a ribbon, and a thermal head (190) to print the RFID tag. The RFID printer further includes an RFID unit (200), which has an operating antenna, a verification antenna and an RFID reader board to record data in an RFID chip of the RFID tag and verify the recorded data, and a control unit, which controls the printer unit and the RFID unit.

Description

RADIO FREQUENCY IDENTIFICATION PRINTER

Technical Field

[1] The present invention relates, in general, to RFID (Radio Frequency IDentification) printers, and, more particularly, to an RFID printer, which has a ribbon roll and RFID tag roll detecting function, a ribbon wrinkling prevention function, a thermal head overheating prevention function and an RFID data collision prevention function. Background Art

[2] Generally, methods using barcodes have been widely used as methods of identifying objects. Recently, according to the development of RF technology, a method, in which information about objects is stored in RFID chips, the RFID chips are attached to the corresponding objects, and the information is read at a remote place, was proposed and has been used.

[3] The above-mentioned barcodes have information about respective corresponding objects according to the EPC or ISO standards. The information about the objects can be discerned by reading the arrangement of the barcodes using a reader.

[4] The RFID technology is a technology that incorporates the use of electromagnetic or electrostatic coupling in the radio frequency portion of the electromagnetic spectrum to uniquely identify an article, animal or person. The RFID technology consists of three components: an antenna and transceiver (typically combined into one reader) and a tag, which is called a transponder. The transponder transmits data, stored therein, to the antenna, and the reader receives the data through the antenna to perceive information about a corresponding object. Here, the transponder is classified into a passive type transponder which is operated by electric waves transmitted from the reader, and an active type transponder, which is operated under its own power.

[5] Of the above-mentioned methods of identifying objects, the RFID method will be mainly used in the future, replacing the barcode method. However, at present, both methods are used. Therefore, a technique that makes it possible for the barcode method and the RFID method to be used together to identify objects is required. To achieve this purpose, an RFID tag, on the outer surface of which printed information such as barcodes for identifying a corresponding object is printed, and which includes therein an RFID chip having information about the object, was proposed. Furthermore, an RFID (radio frequency identification) printer (hereinafter, referred to simply as "RFID printer"), which can print the surface of the RFID tag and, simultaneously, record information about the object in the RFID chip, was also proposed.

[6] FIG. 1 is a perspective view of a typical RFID printer. FIG. 2a is a sectional view of the RFID printer of FIG. 1. FIG. 2b is a functional block diagram of the RFID printer according to the conventional technique. The conventional RFID printer will be described herein below with reference to FIGS. 1, 2a and 2b.

[7] As shown in FIGS. 1 and 2a, the RFID printer according to the conventional technique includes a printer unit 10, which prints an RFID tag 13, and an FRID unit 20, which records and reads information of an RFID chip installed in the RFID tag 13.

[8] The printer unit 10 includes an RFID tag roller 11, on which an RFID tag roll 12 is provided to supply RFID tags 13, a thermal head 13a, which prints the outer surfaces of the RFID tags 13, and a ribbon roll module R, which is provided between the RFID tags 13 and the thermal head 13a and has a first ribbon roller 14 and a second ribbon roller 13 to provide a ribbon 17 for conducting the printing operation. The RFID unit 20 includes an RFID reader board 22, which controls an operation of recording information about an object in the RFID chip of the corresponding RFID tag 13, and an operating antenna 23, which reads the UID of the RFID chip of the RFID tag 13 under the control of the RFID reader board 22, determines whether the RFID tag is normal, and conducts an information recording process when the RFID tag is normal. The RFID unit 20 further includes a verification antenna 24, which reads the data that is recorded in the RFID tag 13 by the operating antenna 23. Furthermore, the conventional RFID printer further includes a control board 21, which controls the printer unit 10 and the RFID unit 20.

[9] In the conventional RFID printer P having the above-mentioned construction, under the control of the control board 210, which is operated using data transmitted from a host computer for controlling the operation of recording of information of the object, the printer unit 10 prints image data, such as a barcode, on the corresponding RFID tag, and the RFID unit 20 determines whether the RFID tag 13 is normal and, thereafter, when the RFID tag 13 is normal, records data of the corresponding object, to which the RFID tag 130 will be mounted, in the RFID chip and verifies the recorded data.

[10] FIG. 2a is a functional block diagram of the RFID unit of the RFID printer R for conducting the verification operation. The RFID reader board 22 includes a first RFID reader unit 22a for transmitting and receiving RFID data of the operating antenna 23, and a second RFID reader unit 22a for transmitting and receiving RFID data of the verification antenna 24. The first and second RFID reader units is connected to a control unit 21a of the control board 21 to conduct the RFID data recording and reading operation.

[11] However, the convention RFID printer P has the following problems.

[12] First, the conventional RFID printer P has a problem in that the RFID tag roll 12 cannot detect the ribbon roll 16. [13] Second, there is a problem in that the ribbon may wrinkle during the operation of the printer, in which case the printing operation cannot be correctly conducted.

[14] Third, in the conventional RFID printer P, because the first RFID reader unit 22a and the second RFID reader unit 22a may communicate with the control unit 21a at the same time, there is a possibility of data collision.

[15] Fourth, the conventional RFID printer P is problematic in that, if a printer control unit (refer to FIG. 7) of the control board 21 malfunctions, the thermal head 13a may be damaged by overheating, and thus the RFID tag 13 may be damaged. Disclosure of Invention Technical Problem

[16] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an RFID printer, which has a ribbon roll and RFID tag roll detecting function, a ribbon wrinkling prevention function, a thermal head overheating prevention function and an RFID data collision prevention function. Technical Solution

[17] In order to accomplish the above object, the present invention provides an RFID

(Radio Frequency IDentification) printer, including: a printer unit, having an RFID tag roll detecting bar provided on an RFID tag roller, on which an RFID tag roll is provided, the RFID tag roll detecting bar contacting at a first end thereof the RFID tag roll and being rotatably supported at a second end thereof by an elastic member, an RFID tag roll switch disposed adjacent to the second end of the RFID tag roll detecting bar to create an RFID tag roll replacement signal when the second end of the RFID tag roll detecting bar comes into contact with the RFID tag roll switch, a ribbon module having two ribbon rollers provided on a path along which an RFID tag moves to control movement of a ribbon, and a thermal head provided above the ribbon to print the RFID tag; an RFID unit provided below the RFID tag and having an operating antenna, a verification antenna and an RFID reader board to record data of a corresponding object in an RFID chip of the RFID tag and verify the recorded data; and a control unit to control the printer unit and the RFID unit.

[18] The ribbon roller may include a rotary slip wheel coupled to each of the ribbon rollers to transmit driving force to the ribbon roller; a drive slip wheel slippably coupled to the rotary slip wheel; a coil spring coupled to the drive slip wheel to transmit the driving force and provide elastic force in a direction in which the ribbon roller is rotated; and a drive wheel coupled to the coil spring to transmit the driving force transmitted from a drive motor.

[19] The RFID reader board may include a switch unit selectively switching operation of the operating antenna and the verification antenna; and an integrated RFID reader unit controlling the switch unit to conduct data communication with the operating antenna or the verification antenna and conducting an operation of recording, reading or verifying the RFID chip using the operating antenna or the verification antenna. [20] The control unit may include: a printer control unit to output a strobe signal for turning on or off the thermal head and output printing data; and a thermal head control unit disposed between the printer control unit and the thermal head to detect malfunction of the printer control unit and turn off the thermal head when the printer control unit malfunctions.

Advantageous Effects

[21] The RFID printer according to the present invention is advantageous in that it indicates times at which it is required to replace an RFID tag roll and a ribbon roll with new ones, thus being more convenient for a user.

[22] Furthermore, the RFID printer of the present invention can prevent a ribbon from wrinkling, prevent data collision between an operating antenna and a verification antenna, and prevent a thermal head from overheating, thus markedly reducing malfunctions of the RFID printer. Furthermore, thanks to printing, the accuracy of data recorded in an RFID chip is ensured, and the user's convenience is increased. In addition, the present invention has an advantage in that the durability of the RFID printer is markedly increased. Brief Description of the Drawings

[23] FIG. 1 is a perspective view of a conventional RFID radio frequency identification printer;

[24] FIG. 2 is a sectional view of the RFID printer of FIG. 1 ;

[25] FIG. 3 is a block diagram of the conventional RFID printer;

[26] FIGS. 4 and 5 are sectional views of an RFID printer having a ribbon detecting unit and an RFID tag roll detecting unit, according to an embodiment of the present invention;

[27] FIG. 6 is an exploded perspective view of a ribbon roll module according to the present invention;

[28] FIG. 7 is a functional block diagram of an operating antenna, a verification antenna and an RFID reader board according to the embodiment of the present invention, having an RFID data collision prevention function;

[29] FIG. 8 is a functional block diagram of a control board having a thermal head control unit that conducts a thermal head overheating prevention function according to the embodiment of the present invention; and

[30] FIG. 9 is a circuit diagram showing an embodiment of the thermal head control unit of FIG. 8.

Best Mode for Carrying Out the Invention

[31] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[32] FIG. 4 is a sectional view of an RFID printer having a ribbon detecting unit and an

RFID tag roll detecting unit, according to the preferred embodiment of the present invention.

[33] As shown in FIG. 4, the RFID printer includes a printer unit 100, which prints

RFID tags 130, and an RFID unit 200, which records and reads data of RFID chips installed in the RFID tags 130.

[34] The printer unit 100 includes an RFID tag roller 110, on which an RFID tag roll 120 for supplying the RFID tag 130 is provided, and an RFID tag roll detecting bar 121, which is elastically and rotatably supported by an elastic member such as a spring, such that a first end thereof contacts the RFID tag roll 120 provided on the RFID tag roller 110, and which has a contact point on a second end thereof. The printer unit 100 further includes an RFID tag roll switch 122, which creates an RFID tag roll replacement signal when the contact point of the RFID tag roll detecting bar 121, which is rotated to the RFID tag roller 110 in response to the use of the RFID tags, is brought into contact with the RFID tag roll switch 122. The printer unit 100 further includes a ribbon roll module R. The ribbon roll module R has a first ribbon roller 140, on which a ribbon roll 160 is provided, a second ribbon roller 150, around which a ribbon 170 that is unwound from the ribbon roll 160 of the first ribbon roller 140 is wound, a ribbon detecting bar 180, which is elastically and rotatably supported by an elastic member such as a spring such that an end thereof contacts the ribbon 170, which moves from the first ribbon roller 140 to the second ribbon roller 150, and a ribbon detecting switch 181, which generates a ribbon roll replacement signal when it comes into contact with the end of the ribbon detecting bar 180. The printer unit 100 further includes a thermal head 190, which is provided above the ribbon and prints the outer surface of the RFID tag by heating the ribbon.

[35] The RFID unit 200 includes an RFID reader board 220, which controls an operation of recording information about an object in the RFID chip of the corresponding RFID tag 130 and selectively switches between the operation of an operating antenna 230 and of a verification antenna 240, and the operating antenna 230, which reads the UID of the RFID chip of the RFID tag 130 in response to the switching control of the RFID reader board 220, determines whether the RFID tag is normal, and conducts a data recording process when the RFID tag is normal. The RFID unit 200 further includes the verification antenna 240, which reads data, which has been recorded on the RFID tag 130 by the operating antenna 230 in response to the switching control of the RFID reader board 220. Furthermore, a control board 210, which controls the printer unit 100 and the RFID unit 200 and prevents the thermal head 190 of the printer unit 100 from overheating, is provided. Here, the control board 210 is the control unit of the present invention. In the drawings, the reference numeral 250 denotes a black marker sensor.

[36] In the RFID printer P having the above-mentioned construction, under the control of a control board 210, which is operated using data transmitted from a host computer for controlling the operation of recording of information of objects, the printer unit 100 prints image data, such as a barcode, on the RFID tag, and the RFID unit 200 determines whether the RFID tag 130 is normal, and, thereafter, if it is determined that the RFID tag 130 is normal, records data of the corresponding object, to which the RFID tag 130 will be mounted, in the RFID chip and verifies the recorded data.

[37] While these operations are conducted, the RFID printer P of FIG. 4 provides a ribbon roll and an RFID tag roll detecting function, a ribbon wrinkling prevention function, a thermal head overheating prevention function and an RFID data collision prevention function.

[38] The ribbon roll detecting function will be explained herein below with reference to

FIG. 4.

[39] After the ribbon roll 160 is installed in the RFID printer P, the ribbon detecting bar

180 is disposed at a position 180a on a path along which the ribbon 170 moves, such that the first end thereof elastically contacts the ribbon 170 using the elasticity of the elastic member such as the spring. When the ribbon is completely used, so that it is completely wound around the second ribbon roller 150, because the ribbon detecting bar 180 can no longer be supported by the ribbon 170, the ribbon detecting bar 180 is disposed at the position 180b. At this time, the contact point of the ribbon detecting bar 180 comes into contact with the ribbon detecting switch 181, and a ribbon replacement signal is consequently output.

[40] FIG. 5 is a sectional view of the RFID printer according to the embodiment of the present invention to illustrate the operation of the RFID tag roll detecting unit. The ribbon roll and RFID tag roll detecting function of the RFID printer of the present invention will be explained herein below with reference to FIG. 5.

[41] At the initial stage of the operation of the RFID printer P, the RFID tag roll detecting bar 121 is disposed at the position 121a. Depending on the use of the RFID tags, the RFID tag roll detecting bar 121 is moved to positions 121b and 121c, that is, towards the RFID tag roller 110. In the present invention, the RFID printer P may be set such that, when the RFID tag roll detecting bar 121 is disposed at the position 121c, an RFID tag roll replacement signal is output. In this case, when the RFID tag roll detecting bar 121 is disposed at the position 121c, the contact point, which is provided on the end of the RFID tag roll detecting bar 121, which is rotatably supported, is brought into contact with the RFID tag roll switch 122. Then, an RFID tag roll replacement signal is output. Here, the position of the RFID tag roll detecting bar, at which an RFID tag roll replacement signal is created, can be selectively set depending on the demand of an operator.

[42] FIG. 6 is an exploded perspective view of the ribbon roll module having the ribbon winkling prevention function.

[43] During the operation of the RFID printer P, the ribbon may not be able to remain tight, that is, may be loosened due to the difference in rotating speeds between the first ribbon roller 140 and the second ribbon roller 150 due to rotational inertia. In this case, as stated in the description of the problem with the conventional technique, a problem of deterioration of the quality of print may result. Therefore, to avoid the above- mentioned problem, the present invention provides an improved structure using the first and second ribbon rollers.

[44] As shown in FIG. 6, the ribbon roll module R having the ribbon wrinkling prevention function includes the first and second ribbon rollers 140 and 150, and a ribbon roller bracket Rl, to which the first and second ribbon rollers 140 and 150 are rotatably mounted. A drive box is provided at a predetermined position in the ribbon roller bracket Rl. Driving force transmitting components for transmitting driving force to the first and second ribbon rollers 140 and 150 are installed in the drive box. An opening of the drive box is closed by a cover R2.

[45] The driving force transmitting components will be explained in detail herein below.

[46] The driving force transmitting components for rotating the first ribbon roller 140 include a first slip wheel 141, a first coil spring 142, which provides elastic force in the direction in which the first slip wheel rotates, and a drive wheel 143, which transmits rotating driving force to the first ribbon roller 140 through the first coil spring 142 and the first slip wheel 141.

[47] In the above construction, the first slip wheel 141 includes a first rotary slip wheel

141a, which is rotated along with the first ribbon roller 140, and a first drive slip wheel 141b, which has a locking notch 141c to which a protrusion 142a, provided on one end of the first coil spring 142, is locked. The first drive slip wheel 141b is coupled to the first rotary slip wheel 141a such that rotating drive force is transmitted from the first drive slip wheel 141b to the first rotary slip wheel 141a, and, when the application of driving force is stopped, the first rotary slip wheel 141a is rotated slightly further with respect to the first drive slip wheel 141b at a predetermined angle in the direction in which it is rotating by the inertia and the elastic force of the first coil spring 142.

[48] Furthermore, the first coil spring 142 has a structure such that protrusions 142a and

142b are provided on respective opposite ends of the spring wire constituting the coil spring body by bending them in directions in which the first coil spring is coupled.

[49] The drive wheel 143 receives driving force from a drive motor (not shown) provided in the RFID printer R and transmits the driving force to the first ribbon roller 140. A locking notch 143b, to which the protrusion 142b of the first coil spring 142 is coupled, is formed in the circumferential outer surface of the drive wheel 143. A coupling boss, which is coupled to the first slip wheel 141 through the first coil spring 142, is provided on the central portion of the drive wheel 143.

[50] The coupling and operation of the driving force transmitting components having the above-mentioned constructions for rotating the first ribbon roller 140 will be explained herein below.

[51] The first slip wheel 141 is mounted to the drive box B such that a protruding part, which is provided on the central portion of the first rotary slip wheel 141a, is inserted into a through hole formed through the surface of the drive box B along the double- dot-dashed line shown in the drawing indicating the coupling relationship, so that the driving force can be transmitted from the first slip wheel 141 to the first ribbon roller 140. Furthermore, the first slip wheel 141 is coupled to the drive wheel 143 in a state in which the first coil spring 142 is interposed therebetween. In detail, the first coil spring 142 is coupled between the first slip wheel 141 and the drive wheel 143 such that the protrusion 142a thereof is locked to the locking notch 141c of the first drive slip wheel 141b of the first slip wheel 141 and the other protrusion 142b is locked to the locking notch 143b of the drive wheel 143.

[52] In the above-mentioned coupling structure, the drive wheel 143 receives driving force from the drive motor (not shown) provided in the RFID printer R and transmits the driving force the first slip wheel 141 through the first coil spring 142, thus rotating the first ribbon roller 140. At this time, the first coil spring 142 is wound in the direction opposite the rotation, thus providing elastic force to the first slip drive wheel 141b in the direction in which it is rotated. Therefore, when the rotation of the drive motor is stopped, the first slip wheel 141 is rotated slightly further at a predetermined angle in the direction in which it is being rotated by the rotational inertia and the elastic force of the first coil spring 142, thus pulling the ribbon such that it is maintained tight, thereby preventing the ribbon from wrinkling. Furthermore, when a tensioning force greater than a predetermined degree is applied to the ribbon, the first rotary slip wheel 141a is no longer rotated, and slips with respect to the first drive slip wheel 141b, thus preventing excessive force from being applied to the ribbon, thereby preventing the ribbon from breaking.

[53] Next, the drive force transmitting components for rotating the second ribbon roller

150 include a second slip wheel 151, a second coil spring 152, which provides elastic force to the second slip wheel 151 in the direction in which the second slip wheel 151 is rotated, and a second drive gear 153 and a second drive gear train 154, which transmit the driving force to the second ribbon roller 150 through the second coil spring 152 and the second slip wheel 151. Here, a drive wheel, illustrated in the description of the components for rotating the first ribbon roller 140, may substitute for the second drive gear 153 and the second drive gear train 154.

[54] In the above construction, the second slip wheel 151 includes a second rotary slip wheel 151a, which is rotated along with the second ribbon roller 150, and a second drive slip wheel 151b, which has a locking notch 151c to which a protrusion 152a provided on one end of the second coil spring 152 is locked. The second drive slip wheel 151b is coupled to the second rotary slip wheel 151a such that rotating drive force is transmitted from the second drive slip wheel 151b to the second rotary slip wheel 151a, and, when the application of driving force is stopped, the second rotary slip wheel 151a is rotated slightly further with respect to the second drive slip wheel 151b at a predetermined angle in the direction in which it is rotated by the inertia and the elastic force of the second coil spring 152.

[55] Furthermore, the second coil spring 152 has a structure such that protrusions 152a and 152b are provided on the respective opposite ends of the spring wire constituting the coil spring body by bending them in directions in which the first coil spring is coupled.

[56] The second drive gear 153 and the second drive gear train 154 receive driving force from a drive motor (not shown) provided in the RFID printer R, and transmit the driving force to the second ribbon roller 150. A locking notch 153b, to which the protrusion 152b of the second coil spring 152 is coupled, is formed in the perimeter of the second drive gear 153. A coupling boss, which is coupled to the second slip wheel 151 through the second coil spring 152, is provided on the central portion of the second drive gear 153.

[57] The coupling and operation of the driving force transmitting components having the above-mentioned construction for rotating the second ribbon roller 150 will be explained herein below.

[58] The second slip wheel 151 is mounted to the drive box B such that a protruding part, which is provided on the central portion of the second rotary slip wheel 151a, is inserted into a through hole formed through the surface of the drive box B along the double-dot-dashed line shown in the drawing indicating the coupling relationship, so that the driving force can be transmitted from the second slip wheel 151 to the second ribbon roller 150. Furthermore, the second slip wheel 151 is coupled to the second drive gear 153 in a state in which the second coil spring 152 is interposed therebetween. In detail, the second coil spring 152 is coupled between the second slip wheel 151 and the second drive gear 153 such that the protrusion 152a thereof is locked to the locking notch 151c of the second drive slip wheel 151b of the second slip wheel 151 and the other protrusion 152b is locked to the locking notch 153b of the second drive gear 153.

[59] In the above-mentioned coupling structure, the second drive gear 153 receives driving force from the drive motor (not shown) provided in the RFID printer R through the second drive gear train 154 and transmits the driving force to the second slip wheel 151 through the second coil spring 152, thus rotating the second ribbon roller 150. At this time, the second coil spring 152 is wound in the direction opposite the rotating direction, thus providing elastic force to the second slip drive wheel 151b in the direction in which it is rotated. Therefore, when the rotation of the drive motor is stopped, the second slip wheel 151 is rotated slightly further at a predetermined angle in the direction in which it is rotated by the rotational inertia and the elastic force of the second coil spring 152, thus pulling the ribbon such that it is maintained tight, thereby preventing the ribbon from wrinkling. Furthermore, when a tensioning force greater than a predetermined degree is applied to the ribbon, the second rotary slip wheel 151a is no longer rotated, and slips with respect to the second drive slip wheel 151b, thus preventing excessive force from being applied to the ribbon, thereby preventing the ribbon from breaking.

[60] Here, the driving force transmitting components for rotating the second ribbon roller 150 may have the same construction as the driving force transmitting components for rotating the first ribbon roller 140. As such, in the embodiment of the present invention shown in FIG. 6, the rotary slip wheel corresponds to the first and second rotary slip wheels 141a and 151a, the drive slip wheel corresponds to the first and second drive slip wheels 141b and 151b, and, in the case of the first ribbon roller 140, the drive wheel corresponds to the drive wheel 143, and, in the case of the second ribbon roller 150, the drive wheel corresponds to the second drive gear 153 and the second drive gear train 154.

[61] Meanwhile, the RFID printer P of the present invention has the function of preventing RFID data collision between the operating antenna 230 and the verification antenna 240. FIG. 7 is a functional block diagram of the operating antenna 230, the verification antenna 240 and the RFID reader board 200 according to the embodiment of the present invention having the RFID data collision prevention function.

[62] As shown in FIG. 7, the RFID reader board 220 of the present invention for preventing RFID data collision includes a switch unit 225, which selectively switches the operation of the operating antenna 230 and the verification antenna 240, and an integrated RFID reader unit 220', which controls the RFID chip recording and reading operation of the operating antenna 230 and the verification antenna 240 through the switch unit 225. [63] When the operation of the operating antenna 230 is required, the integrated RFID reader unit 220' switches the switch unit 225 such that the integrated RFID reader unit 220' conducts data communication only with the operating antenna 230. When the operation of the verification antenna 240 is required, the integrated RFID reader unit 220' switches the switch unit 225 such that the integrated RFID reader unit 220' conducts data communication only with the verification antenna 240. As such, the present invention controls both the operating antenna and the verification antenna using only a single reader, thus preventing RFID data collisions attributable to the simultaneous operation of the operating antenna 230 and the verification antenna 240.

[64] Furthermore, the RFID printer P of the present invention has the thermal head overheating prevention function. FIG. 8 is a functional block diagram of the control board 210 having a thermal head control unit that conducts the thermal head overheating prevention function according to the embodiment of the present invention.

[65] The construction and operation of the present invention for conducting the thermal head overheating prevention function will be explained herein below with reference to FIG. 8.

[66] As shown in FIG. 8, the control board 210 for preventing the thermal head from overheating includes a printer control unit 211, which outputs a strobe (STRl) signal for turning on/off the thermal head 190 and outputs printing data, and the thermal head control unit 213, which detects malfunction of the printer control unit 211 and forcibly turns off the thermal head control unit 213 when a malfunction of the printer control unit 211 is detected.

[67] In the above-mentioned construction, when it is desired to conduct a printing operation, the printer control unit 211 outputs a strobe signal for turning on the thermal head 190, thus conducting the printing operation. Here, if the printer control unit 211 continuously outputs strobe signals due to a malfunction of the printer control unit 211, because the thermal head 190 maintain a state in which it is turned on, it is overheated. Hence, the thermal head 190 may be damaged, or the quality of a print image may be deteriorated. In the present invention, to avoid this problem, when the duration of output of strobe signals exceeds a predetermined time, the thermal head control unit 213 detects this and outputs a signal for turning off the thermal head 190, thus preventing the thermal head from overheating.

[68] FIG. 9 is a circuit diagram showing an embodiment of the thermal head control unit of FIG. 8 having the thermal head overheating prevention function. The circuit diagram of FIG. 9 illustrates a circuit which is operated using an RC time constant such that, when the RC time constant exceeds a predetermined value, the thermal head is forcibly turned off. The circuit includes an inverter 310, which inverts a strobe signal input from the printer control unit 211, a first flip-flop 310, which receives a signal output from the inverter 310 though a clock terminal and outputs the signal through an inverting terminal (Q bar), and an OR gate 330, which receives both the signal output from the inverting terminal of the first flip-flop 310 and the strobe signal from the printer control unit 211, conducts an OR calculation, and outputs the result to the thermal head 190. Furthermore, on an inverting terminal output signal line of the first flip-flop 310, a transistor 370, which receives the inverting terminal output signal of the first flip-flop 320 through a collector terminal, and having a grounded emitter terminal, is provided, and a time constant detecting circuit 340, which includes a resistor R34 and a capacitor C33, respective first ends of which are grounded, and serves to detect a time constant. In addition, an AND gate 350, which receives the strobe signal of the printer control unit 211 and an output signal of the time constant detecting circuit 340, conducts an AND calculation, and outputs the result, is provided on the OR gate 330 side of the time constant detecting circuit 340. Furthermore, on an output side of the AND gate 350, a second flip-flop 360 is connected to the first flip- flop 320 such that the output signal of the AND gate 350 is input through a clear terminal CL of the second flip-flop 360. In detail, the second flip-flop 360 receives the output signal of the AND gate 350 through the clear terminal CL thereof and receives the strobe signal STRl of the printer control unit 211 through a clock terminal CLK thereof, and an output terminal Q of the second flip-flop 360 is connected to a base terminal of the transistor 370.

[69] The thermal head control unit 213 having the above-mentioned construction of FIG.

9 checks the time for which charging power of the time constant circuit 340 was discharged when the printer control unit 211 malfunctions, such that strobe signals are continuously output. Thereafter, if the checked time exceeds a predetermined time, the AND gate 350 transmits a clear signal to the first flip-flop 320, so that the first flip- flop 320 outputs a thermal head turning off signal through the inverting terminal (Q bar), thus turning off the thermal head 190. Furthermore, the second flip-flop 360 is operated such that, when the printer control unit 211 is normally operated, the capacitor of the time constant circuit is continuously charged, thus preventing the thermal head 190 from being turned off while the printer control unit is normally operated. Thanks to such operation, the present invention can prevent the thermal head from overheating when the printer control unit 211 malfunctions.

Claims

[1] An RFID (Radio Frequency IDentification) printer, comprising: a printer unit, comprising an RFID tag roll detecting bar provided on an RFID tag roller, on which an RFID tag roll is provided, the RFID tag roll detecting bar contacting at a first end thereof the RFID tag roll and being rotatably supported at a second end thereof by an elastic member, an RFID tag roll switch disposed adjacent to the second end of the RFID tag roll detecting bar to create an RFID tag roll replacement signal when the second end of the RFID tag roll detecting bar comes into contact with the RFID tag roll switch, a ribbon module having two ribbon rollers provided on a path along which an RFID tag moves to control movement of a ribbon, and a thermal head provided above the ribbon to print the RFID tag; an RFID unit provided below the RFID tag and having an operating antenna, a verification antenna and an RFID reader board to record data of a corresponding object in an RFID chip of the RFID tag and verify the recorded data; and a control unit to control the printer unit and the RFID unit.

[2] The RFID printer according to claim 1, wherein the ribbon roller comprises: a rotary slip wheel coupled to each of the ribbon rollers to transmit driving force to the ribbon roller; a drive slip wheel slippably coupled to the rotary slip wheel; a coil spring coupled to the drive slip wheel to transmit the driving force and provide elastic force in a direction in which the ribbon roller is rotated; and a drive wheel coupled to the coil spring to transmit the driving force transmitted from a drive motor.

[3] The RFID printer according to claim 1, wherein the RFID reader board comprises: a switch unit selectively switching operation of the operating antenna and the verification antenna; and an integrated RFID reader unit controlling the switch unit to conduct data communication with the operating antenna or the verification antenna and conducting an operation of recording, reading or verifying the RFID chip using the operating antenna or the verification antenna.

[4] The RFID printer according to claim 1, wherein the control unit comprises: a printer control unit to output a strobe signal for turning on or off the thermal head and output printing data; and a thermal head control unit disposed between the printer control unit and the thermal head to detect malfunction of the printer control unit and turn off the thermal head when the printer control unit malfunctions.