UNIVERSAL SERIAL BUS CONNECTING APPARATUS

Abstract: A USB connecting apparatus includes D+ and D- optical communication modules. The D+ optical communication module, which is connected between D+ data terminals of transceivers, converts a D+ electrical signal from the D+ data terminal of the first or second transceiver into a D+ optical signal and transmits the D+ optical signal, and restores the transmitted D+ optical signal to a D+ electrical signal and inputs the D+ electrical signal to the D+ data terminal of the second or first transceiver. The D- optical communication module, which is connected between D- data terminals of the transceivers, converts a D- electrical signal from the D- data terminal of the first or second transceiver into a D- optical signal and transmits the D- optical signal, and restores the transmitted D- optical signal to a D- electrical signal and inputs the D- electrical signal to the D- data terminal of the second or first transceiver.

Description: UNIVERSAL SERIAL BUS CONNECTING APPARATUS Technical Field The present invention relates to a universal serial bus (USB) connecting apparatus for connecting a computer to peripheral devices, and more particularly, to a USB connecting apparatus for interconnecting first and second transceivers for USB. Background Art USB is a Plug-and-Play (PnP) interface for connecting a computer to peripheral devices. The USB ports function as ports for keyboards and mice and parallel and serial ports. Thus, in a case where all ports of a computer are replaced with USB ports, there is no need for a user to distinguish a connector and a cable. Furthermore, using USB in peripheral devices allows a computer to perceive attachment/detachment to/from the USB port while the computer is running. USB versions 1.0, 1.1, and 2.0 for a USB interface standard have been introduced. The USB versions 1.0, 1.1 and 2.0 relate to low-speed, full-speed, and ultrahigh-speed USB standards that support data transfer rates of 1.5, 12, and 480 megabytes per second (Mbps), respectively. Typically, USB includes a power-voltage line of +5 V, a D+ data line, a D- data line, and a ground line. D+ and D- data signals carried on the D+ data line and the D- data line, respectively, are in a logic low state at single- end regions, while both signals are in opposite states in the remaining regions. FIG. 1A shows a state in which a USB connection between a computer 10 and a full-speed peripheral device 30 has been made by a conventional electrical transmission cable 20. Here, the full-speed peripheral device 30 refers to a device that conforms to a full-speed USB standard. The computer 10 or the full-speed peripheral device 30 in FIG. 1 A may be replaced with a hub that serves as a connector between them. Referring to FIG. 1A, a power-voltage (Vcc) line L., of +5 V, a D+ data line L 2 , a D- data line L 3 , and a ground (GND) line L 4 come from a first transceiver 101 for USB of the computer 10 and are connected to terminals Pιι> Pi 2 , Pi 3 , anc ' Pi 4 °f a USB port, respectively. Here, pull-down resistors R^ are connected between each of the data lines L 2 and L 3 and the ground line L 4 . ' Similarly, a power-voltage (Vcc) line L,' of +5 V, a D+ data line L 2 ', a D- data line L 3 \ and a ground (GND) line L 4 ' come from a second transceiver 301 for USB of the full-speed peripheral device 30 and are connected to terminals P 21 , P 22, P 23, and P 24 of a USB port, respectively. Here, a pull-up resistor R 2 is connected between the D+ data line L 2 ' and the power-voltage line L,'. The terminals P^, P 12, P 13ι and P 14 of the first transceiver 101 for USB are connected to the terminals P 21 , P 22? P 23ι and P 24 of the second transceiver 301 for USB, respectively, by the electrical cable 20. The voltage-power terminal P^ of the first transceiver 101 is connected to the power-voltage terminal P 21 of the second transceiver 301 by an electrical line of the electrical cable 20. The D+ data terminal P 12 of the first transceiver 101 is connected to the D+ data terminal P 22 of the second transceiver 301 by an electrical line of the electrical cable 20. The D- data terminal P 13 of the first transceiver 101 is connected to the D- data terminal P 23 of the second transceiver 301 by an electrical line of the electrical cable 20. The ground terminal P 14 of the first transceiver 101 is connected to the ground terminal P 24 of the second transceiver 301 by an electrical line of the electrical cable 20. FIG. 1 B shows a state in which a USB connection between the computer 10 and a low-speed peripheral device 40 has been made by the conventional electrical transmission cable 20. Here, the low-speed peripheral device 40 refers to a device that conforms to a low-speed USB standard. The computer 10 or the low-speed peripheral device 40 in FIG. 1 B may be replaced with a hub that serves as a relay-interface between them. Referring to FIG. 1 B, a power-voltage (Vcc) line L., of +5 V, a D+ data line L 2 , a D- data line L 3 , and a ground (GND) line L 4 come from the first transceiver 101 for USB of the computer 10 and are connected to terminals P 11( P 12t P 13ι and P 14 of a USB port, respectively. Here, pull-down resistors R., are connected between each of the data lines L 2 and L 3 and the ground line L 4 . Similarly, a power-voltage (Vcc) line L,' of +5 V, a D+ data line L 2 ', a D- data line L 3 ', and a ground (GND) line L 4 ' come from a second transceiver 401 for USB of the low-speed peripheral device 40 and are connected to terminals P 21 , P 22 , P 23, anc l ^ 24 of a USB port, respectively. Here, a pull-up resistor R 2 is connected between the D- data line L 3 ' and the power-voltage line L,'. The terminals P^, P 12ι P 13j and P 14 of the first transceiver 101 for USB are connected to the terminals P 21 , P 22 P 23ι and P 24 of the second transceiver 401 for USB, respectively, by the electrical cable 20. The voltage-power terminal P^ of the first transceiver 101 is connected to the power-voltage terminal P 21 of the second transceiver 401 by an electrical line of the electrical cable 20. The D+ data terminal P 12 of the first transceiver 101 is connected to the D+ data terminal P 22 of the second transceiver 401 by an electrical line of the electrical cable 20. The D- data terminal P 13 of the first transceiver 101 is connected to the D- data terminal P 23 of the second transceiver 401 by an electrical line of the electrical cable 20. The ground terminal P 14 of the first transceiver 101 is connected to the ground terminal P 24 of the second transceiver 401 by an electrical line of the electrical cable 20. Referring to FIG. 2, the conventional electrical cable 20 for USB is composed of a power-voltage line 21 between the power-voltage terminals P^ and P 12 of FIG. 1A or 1 B, a D+ electrical line 22 between the D+ data terminals P 12 and P 22 of FIG. 1 A or 1 B, a D- electrical line 23 between the D- data terminals P 13 and P 23 of FIG. 1A or 1 B, a ground line 24 between the ground terminals P 14 and P 24 of FIG. 1A or 1 B, and a shield 25 for minimizing noise. The USB connection method using the conventional electrical transmission cable 20 has several problems due to internal resistance of an electrical line itself. First, communication speed and maximum communication distance decrease. Second, a large amount of electrical noise is generated. Third, a difference in impedances between the D+ and D- electrical lines 22 and 23 is large. Due to the above problems, the maximum communication distance is limited to 5 m or less, if two devices are directly connected by an electrical cable for USB. Thus, as shown in FIG. 3, a plurality of hubs 50 are used to increase an effective communication distance. However, in this case, since D+ and D- signals are delayed in the hubs 50 and the cables 20, a maximum number of the hubs 50 is restricted to six. Thus, if five hubs 50 are used, the maximum communication distance between the computer 10 and the peripheral device 30 or 40 is limited to 30 m or less. Disclosure of the Invention To solve the above problems, it is an object of the present invention to provide a Universal Serial Bus (USB) connecting apparatus for interconnecting first and second transceivers for USB, which provides high communication speed and long maximum communication distance, eliminates electrical noise, and minimizes a difference in impedances between D+ and D- communication lines. To accomplish the above object, the present invention provides a USB connecting apparatus for interconnecting first and second transceivers for USB. The USB connecting apparatus includes a D+ optical communication module, a D- optical communication module, and first and second electrical lines. The D+ optical communication module, which is connected between D+ data terminals of the transceivers, converts a D+ electrical signal from the D+ data terminal of the first or second transceiver into a D+ optical signal and transmits the D+ optical signal, and restores the transmitted D+ optical signal to a D+ electrical signal and inputs the D+ electrical signal to the D+ data terminal of the second or first transceiver. The D- optical communication module, which is connected between D- data terminals of the transceivers, converts a D- electrical signal from the D- data terminal of the first or second transceiver into a D- optical signal and transmits the D~ optical signal, and restores the transmitted D- optical signal to a D- electrical signal and inputs the D- electrical signal to the D- data terminal of the second or first transceiver. The first electrical line is connected between power-voltage terminals of the transceivers, while the second electrical line is connected between ground terminals of the transceivers. According to the USB connecting apparatus, optical communications are accomplished by the D+ and D- optical communication modules. Thus, communication speed and effective communication distance increase, electrical noise is removed, and the difference in impedances between D+ and D- communication lines is minimized. Preferably, the D+ optical communication module includes a first light emitting portion, a first optical fiber line, a second light receiving portion, a second light emitting portion, a second optical fiber line, and a first light emitting portion. The first light emitting portion converts a D+ electrical signal from the D+ data terminal of the first transceiver into a D+ optical signal. The first optical fiber line transmits the D+ optical signal from the first light emitting portion to the second transceiver. The second light receiving portion restores the D+ optical signal from the first optical fiber line to a D+ electrical signal and inputs the restored D+ electrical signal to the D+ data terminal of the second transceiver. The second light emitting portion converts a D+ electrical signal from the D+ data terminal of the second transceiver into a D+ optical signal. The second optical fiber line that transmits the D+ optical signal from the second light emitting portion to the first transceiver. The first light receiving portion that restores the D+ optical signal from the second optical fiber line to a D+ electrical signal and inputs the restored D+ electrical signal to the D+ terminal of the first transceiver. Furthermore, it is preferable that, in the D+ optical communication module, light is transmitted through the first or second optical fiber line only when the D+ electrical signal from the D+ data terminal of the first or second transceiver is in a logic low state. Here, it is preferable that the D+ optical communication module further includes first and second control switching portions. The first control switching portion prevents the first light emitting portion from operating only when light is transmitted through the second optical fiber line. The second control switching portion prevents the second light emitting portion from operating only when light is transmitted through the first optical fiber line. Accordingly, the problem of received signals being retransmitted from D+ data terminals of the first and second transceivers can be overcome. Meanwhile, it is preferable that the D- optical communication module includes a third light emitting portion, a third optical fiber line, a fourth light receiving portion, a fourth light emitting portion, a fourth optical fiber line, and a third light receiving portion. The third light emitting portion converts a D- electrical signal from the D- data terminal of the first transceiver into a D- optical signal. The third optical fiber line transmits the D- optical signal from the third light emitting portion to the second transceiver. The fourth light receiving portion restores the D- optical signal from the third optical fiber line to a D- electrical signal and inputs the restored D- electrical signal to the D- data terminal of the second transceiver. The fourth light emitting portion converts a D- electrical signal from the D- data terminal of the second transceiver into a D- optical signal. The fourth optical fiber line that transmits the D- optical signal from the fourth light emitting portion to the first transceiver. The third light receiving portion restores the D- optical signal from the fourth optical fiber line to a D- electrical signal and inputs the restored D- electrical signal to the D- terminal of the first transceiver. It is preferable that, in the D- optical communication module, light is transmitted through the first or second optical fiber line only when the D- electrical signal from the D- data terminal of the first or second transceiver is in a logic high state. Here, it is preferable that the D+ optical 5 communication module further includes third and fourth control switching portions. The third control switching portion prevents the third light emitting portion from operating only when light is transmitted through the fourth optical fiber line. The fourth control switching portion that prevents the third light emitting portion from operating only when light is transmitted through 0 the third optical fiber line. Accordingly, the problem of the received signal being retransmitted from the D+ data terminals of the first and second transceivers can be overcome. Brief Description of the Drawings s FIG. 1A shows a state in which a USB connection between a computer and a full-speed peripheral device has been made by a conventional electrical transmission cable; FIG. 1 B shows a state in which a USB connection between a computer and a low-speed peripheral device has been made by a o conventional electrical transmission cable; FIG. 2 is a perspective view showing the internal structure of a conventional electrical cable for USB; FIG. 3 shows a state in which hubs are used to increase transmission distance of the conventional electrical cable for USB; 5 FIG.4 shows a state in which a USB connection between a computer and a full-speed peripheral device has been made by a connecting apparatus according to the present invention; FIG.5 shows a state in which a USB connection between a computer and a low-speed peripheral device has been made by a connecting 0 apparatus according to the present invention; FIG. 6 is a circuit diagram showing the internal structure of the D+ optical communication module of the connecting apparatus of FIG. 4; and FIG. 7 is a circuit diagram showing the internal structure of the D- optical communication module of the connecting apparatus of FIG. 4. Best mode for carrying out the Invention FIG. 4 shows a state in which a Universal Serial Bus (USB) connection between a computer 10 and a full-speed peripheral device 30 has been made by a connecting apparatus 100 according to the present invention. The same reference numeral in FIG. 4 as in FIG. 1 represent an element for performing the same function. Referring to FIG. 4, the USB connecting apparatus 100 includes a D+ optical communication module 110, a D- optical communication module 120, and first and second electrical lines L 101 and L 104 . The D+ optical communication module 110, which is connected between D+ data terminals P 12 and P 22 of first and second transceivers 101 and 301 , converts a D+ electrical signal from the D+ data terminal P 12 or P 22 of the first or second transceiver 101 or 301 into a D+ optical signal and transmits the D+ optical signal. Also, the D+ optical communication module 110 restores the transmitted D+ optical signal to a D+ electrical signal and inputs the restored D+ electrical signal to the D+ data terminal P 22 or P 12 of the second or first transceiver 301 or 101. The D+ optical communication module 110 includes a first module M1 , a second module M2, a first optical fiber line 111 , and a second optical fiber line 113. The operation of each component in the D+ optical communication module 110 will be described below with reference to FIG. 6. A D- optical communication module 120, which is connected between D- data terminals P 13 and P 23 of the first and second transceivers 101 and 301 , converts a D- electrical signal from the D- data terminal P 13 or P 23 of the first or second transceiver 101 or 301 into a D- optical signal and transmits the D- optical signal. Also, the D- optical communication module 120 restores the transmitted D- optical signal to a D- electrical signal and inputs the restored D- electrical signal to the D- data terminal P 23 or P 13 of the second or first transceiver 301 or 101. The D- optical communication module 120 includes a third module M3, a fourth module M4, a third optical fiber line 121 , and a fourth optical fiber Iine123. The operation of each component in the D- optical communication module 120 will be described below with reference to FIG. 7. The first electrical line L 101 is connected between power-voltage terminals P and P 21 of the transceivers 101 and 301 , while the second electrical line L 104 is connected between ground terminals P 14 and P 24 of the transceivers 101 and 301. FIG. 5 shows a state in which a USB connection between the computer 10 and a low-speed peripheral device 40 has been made by a connecting apparatus 200 according to the present invention. The same reference numerals appearing in FIG. 5 as in FIG. 1 B represent an element that performs the same function. Referring to FIG. 5, the USB connecting apparatus 200 includes a D+ optical communication module 210, a D- optical communication module 220, and first and second electrical lines L 101 and L 104 . The D+ optical communication module 210, which is connected between D+ data terminals P 12 and P 22 of first and second transceivers 101 and 401 , converts a D+ electrical signal from the D+ data terminal P 12 or P 22 of the first or second transceiver 101 or 401 into a D+ optical signal and transmits the D+ optical signal. Also, the D+ optical communication module 210 restores the transmitted D+ optical signal to a D+ electrical signal and inputs the restored D+ electrical signal to the D+ data terminal P 22 or P 12 of the second or first transceiver 401 or 101. The D+ optical communication module 210 includes a third module M3, a fourth module M4, a third optical fiber line 121 , and a fourth optical fiber line 123. The operation of each component in the D+ optical communication module 210 is the same as that in the D- optical communication module 120, and thus a detailed explanation will be omitted. A D- optical communication module 220, which is connected between D- data terminals P 13 and P 23 of the first and second transceivers 101 and 401 , converts a D- electrical signal from the D- data terminal P 13 or P 23 of the first or second transceiver 101 or 401 into a D- optical signal and transmits the D- optical signal. Also, the D- optical communication module 120 restores the transmitted D- optical signal to a D- electrical signal and inputs the restored D- electrical signal to the D- data terminal P 23 or P 13 of the second or first transceiver 401 or 101. The D- optical communication module 220 includes a first module M1 , a second module M2, a first optical fiber line 111 , and a second optical fiber linel 13. The operation of each component in the D- optical communication module 220 is the same as that in the D+ optical communication module 110, and thus a detailed explanation will be omitted. The first electrical line L 101 is connected between power-voltage terminals P^ and P 21 of the transceivers 101 and 401 , while the second electrical line L 104 is connected between ground terminals P 14 and P 24 of the transceivers 101 and 401. Referring to FIG.6, the connecting apparatus 100 of FIG. 4 includes the first module M1 , the second module M2, the first optical fiber line 111 , and the second optical fiber line 113. The first module M1 includes a first light emitting portion LE1 , a first light receiving portion PR1 , and a first control switching portion CS1. The second module M2 includes a second light emitting portion LE2, a second light receiving portion PR2, and a second control switching portion CS2. The first light emitting portion LE1 converts a D+ electrical signal from the D+ data terminal P 12 of the first transceiver (101 of FIG. 4) into a D+ optical signal. The first optical fiber line 111 transmits the D+ optical signal from the first light emitting portion LE1 to the second transceiver (301 of FIG. 4). The second light receiving portion PR2 restores the D+ optical signal from the first optical fiber line 111 to a D+ electrical signal and inputs the D+ electrical signal to the D+ data terminal P 22 of the second transceiver 301. The second light emitting portion LE2 converts a D+ electrical signal from the D+ data terminal P 22 of the second transceiver 301 into a D+ optical signal. The second optical fiber line 113 transmits the D+ optical signal from the second light emitting portion LE2 to the first transceiver 101. The first light receiving portion PR1 restores the D+ optical signal from the second optical fiber line 113 to a D+ electrical signal and inputs the D+ electrical signal to the D+ data terminal P 12 of the first transceiver 101. Here, light is transmitted through the first or second optical fiber line 111 or 113 only when a D+ electrical signal from the D+ data terminal P 12 or P 22 of the first or second transceiver 101 or 301 is in a logic low state. The first contro\ switching portion CS1 prevents the first light emitting portion LE1 from operating only when light is transmitted through the second optical fiber line 113. Similarly, the second control switching portion CS2 prevents the second light emitting portion LE2 from operating only when light is transmitted through the first optical fiber line 111. Accordingly, retransmission of received signals from the D+ data terminals P 12 and P 22 of the first and second transceivers 101 and 301. can be prevented. If a logic high signal is input to the D+ data terminal P 12 of the first transceiver 101 , a PNP transistor TR.,., of the first light emitting portion LE1 is turned off to prevent current from flowing through a light emitting element LD1 such as a resonant cavity light emitting diode (RCLED). Thus, since light is not generated by the light emitting element LD1 , a voltage is not generated by a light receiving element PD2 of the second light receiving portion PR2. Furthermore, an NPN transistor TR 23 of the second light receiving portion PR2 is turned off, so that current flows into a pull-down resistor R 24 of the second light receiving portion PR2 through the pull-up resistor (R 2 of FIG. 4) of the second transceiver 301. Accordingly, a logic high D+ signal is output through the D+ data terminal P 22 of the second transceiver 301. Here, an NPN transistor TR 22 of the second control switching portion CS2 is turned off, so that the second light emitting portion LE2 can operate normally. Similarly, if a logic high signal is input to the D+ data terminal P 22 of the second transceiver 301 , a PNP transistor TR 21 of the second light emitting portion LE2 is turned off to prevent current from flowing through a light emitting element LD2 such as a resonant cavity light emitting diode (RCLED). Thus, since light is not generated by the light emitting element LD2, a voltage is not generated by a light receiving element PD1 of the first light receiving portion PR1. Furthermore, an NPN transistor TR 13 of the first light receiving portion PR1 is turned off, so that current flows into the pulldown resistor (R., of FIG. 4) of the first transceiver 101 through the pull-up resistor R 2 of the first light emitting element LE1 and a terminal line L 102 . Accordingly, a logic high D+ signal is output through the D+ data terminal P 12 of the first transceiver 101. Here, an NPN transistor TR 12 of the first control switching portion CS1 is turned off, so that the first light emitting portion LE1 can operate normally. On the other hand, if a logic low signal is input to the D+ data terminal P 12 of the first transceiver 101 , the PNP transistor TR„ of the first light emitting portion LE1 is turned on, which causes current to flow from the power-voltage line L 101 into the ground line L 104 through a resistor R G1 the light emitting element LD1 , the PNP transistor TR„ and a resistor R G3 . Thus, light is generated by the light emitting element LD1 of the first light emitting portion LE1, and the generated light is incident on the light receiving element PD2 of the second light receiving portion PR2 through the first optical fiber line 111. Then, since a voltage is generated by the light receiving element PD2 of the second light receiving portion PR2, current flows into the ground line L 104 through the resistor R 13 . Furthermore, the NPN transistor TR 23 of the second light receiving portion PR2 is turned on, so that current flows into the ground line L 104 through the pull-up resistor (R 2 of FIG. 4), a terminal line L 102 ', and the NPN transistor TR 23 of the second light receiving portion PR2. Thus, a logic low D+ signal is output through the D+ data terminal P 22 of the second transceiver 301. In this case, since the NPN transistor TR 22 of the second control switching portion CS2 is turned on, the second light emitting portion LE2 cannot operate. In this way, retransmission of the received logic low signal from the D+ data terminal P 22 of the second transceiver 301 can be prevented. In the same manner, if a logic low signal is input to the D+ data terminal P 22 of the second transceiver 301 , the PNP transistor TR 21 of the second light emitting portion LE2 is turned on, which causes current to flow from the power-voltage line L 101 into the ground line L 104 through a resistor R G2ι the light emitting element LD2, the PNP transistor TR 21 and a resistor R 21 . Thus, light is generated by the light emitting element LD2 of the second light emitting portion LE1 , and the generated light is incident on the light receiving element PD1 of the first light receiving portion PR1 through the second optical fiber line 113. Since a voltage is generated by the light receiving element PD1 of the first light receiving portion PR1 , the NPN transistor TR 13 is turned on, so that the potential of the D+ data terminal P 12 of the first transceiver 101 approaches a ground potential. That is, a logic low D+ signal is output through the D+ data terminal P 12 of the first transceiver 101. In this case, since the NPN transistor TR 12 of the first control switching portion CS1 is turned on, the first light emitting portion LE1 cannot operate. Accordingly, retransmission of the received logic low signal from the D+ data terminal P 12 of the first transceiver 101 can be prevented. Referring to FIG. 7, the D- optical communication module 120 of the connecting apparatus 100 of FIG. 2 includes the first module M3, the fourth module M4, the third optical fiber line 121 , and the fourth optical fiber line 123. The third module M3 includes a third light emitting portion LE3, a third light receiving portion PR3, and a third control switching portion CS3. The fourth module M4 includes a fourth light emitting portion LE4, a fourth light receiving portion PR4, and a fourth control switching portion CS4. The third light emitting portion LE3 converts a D- electrical signal from the D- data terminal P 13 of the first transceiver (101 of FIG. 4) into a D+ optical signal. The third optical fiber line 121 transmits the D- optical signal from the third light emitting portion LE3 to the second transceiver (301 of FIG. 4). The fourth light receiving portion PR4 restores the D+ optical signal from the third optical fiber line 121 to a D- electrical signal and inputs the D- electrical signal to the D- data terminal P 23 of the second transceiver 301. The fourth light emitting portion LE4 converts a D- electrical signal from the D- data terminal P 23 of the second transceiver 301 into a D- optical signal. The fourth optical fiber line 123 transmits the D- optical signal from the fourth light emitting portion LE4 to the first transceiver 101. The third light receiving portion PR3 restores the D- optical signal from the fourth optical fiber line 123 to a D- electrical signal and inputs the D- electrical signal to the D- data terminal P 13 of the first transceiver 101. Here, light is transmitted through the third or fourth optical fiber line 121 or 123 only when a D- electrical signal from the D- data terminal P 13 or P 23 of the first or second transceiver 101 or 301 is in a logic high state. The third control switching portion CS3 prevents the third light emitting portion LE3 from operating only when light is transmitted through the fourth optical fiber line 123. Similarly, the fourth control switching portion CS4 prevents the fourth light emitting portion LE4 from operating only when light is transmitted through the third optical fiber line 121. Accordingly, retransmission of received signals from the D+ data terminals P 12 and P 22 of the first and second transceivers 101 and 301 can be prevented. If a logic high signal is input to the D- data terminal P 13 of the first transceiver 101 , a NPN transistor TR 31 of the third light emitting portion LE3 is turned on, which causes current to flow from the power-voltage line L 101 into the ground line L 104 through a resistor R G5 a light emitting element LD3, the NPN transistor TR 31 and a resistor R G6 . Thus, light is generated by the light emitting element LD3 of the third light emitting portion LE3, such as RCLED, and the generated light is incident on a light receiving element PD4 of the fourth light receiving portion PR4 through the third optical fiber line 121. Then, since a voltage is generated by the light receiving element PD4 of the fourth light receiving portion PR4, current flows into the ground line L 104 through a resistor R 43 , an NPN transistor TR 43 and a pull-down resistor R 44 . Furthermore, the NPN transistor TR 43 of the fourth light receiving portion PR4 is turned on, so that current flows into the ground line L 104 through the NPN transistor TR 43 and the pull-down resistor R 44 . Thus, since the potential of the D- data terminal P 23 of the second transceiver 301 approaches a power supply voltage Vcc, a logic high D- signal is output. In this case, since an NPN transistor TR 42 of the fourth control switching portion CS4 is turned on, the fourth light emitting portion LE4 cannot operate. In this way, retransmission of the received logic high signal from the D- data terminal P 23 of the second transceiver 301 can be prevented. In the same manner, if a logic high signal is input to the D- data terminal P 23 of the second transceiver 301 , an NPN transistor TR 41 of the fourth light emitting portion LE4 is turned on, which causes current to flow from the power-voltage line L 101 into the ground line L 104 through a resistor R 41ι a light emitting element LD4, an NPN transistor TR 41 and a resistor R G4 . Thus, light is generated by the light emitting element LD4 of the fourth light emitting portion LE4, and the generated light is incident on a light receiving element PD3 of the third light receiving portion PR3 through the fourth optical fiber line 123. Since a voltage is generated by the light receiving element PD3 of the third light receiving portion PR3, current flows into the pull-down resistor (R., of FIG. 4) of the first transceiver 101 through a resistor R 33 an NPN transistor TR 33 , a terminal line L 103 , and the D- data terminal P 13 . Furthermore, the NPN transistor TR 33 of the third light receiving portion PR3 is turned on, so that current flows from the power- voltage line L 101 into pull-down resistor (R., of FIG. 4) of the first transceiver 101 through the NPN transistor TR 33 , the terminal line L 103 , and the D- data terminal P 13 . Thus, since the potential of the D- data terminal P 13 of the first transceiver 101 approaches a power supply voltage Vcc, a logic high D- signal is output. In this case, since an NPN transistor TR 32 of the third control switching portion CS3 is turned on, the third light emitting portion LE3 cannot operate. Accordingly, retransmission of the received logic high signal from the D- data terminal P 13 of the first transceiver 101 can be prevented. On the other hand, if a logic low signal is input to the D- data terminal P 13 of the first transceiver 101 , the NPN transistor TR 31 of the third light emitting portion LE3 is turned off, so as to prevent current from flowing through the light emitting element LD3. Thus, since light is not generated by the light emitting element LD3, a voltage is not generated by the light receiving element PD4 of the fourth light receiving portion PR4. Furthermore, the NPN transistor TR 43 of the fourth light receiving portion PR4 is turned off to bring the D- data terminal P 23 of the second transceiver 301 into a floating state. That is, a logic low D- signal is output through the D- data terminal P 23 of the second transceiver 301. Here, since the NPN transistor TR 42 of the fourth control switching portion CS4 is turned off, the fourth light emitting portion LE4 can operate normally. Similarly, if a logic low signal is input to the D- data terminal P 23 of the second transceiver 301 , the NPN transistor TR 41 of the fourth light emitting portion LE4 is turned off to prevent current from flowing through the light emitting element LD4. In this case, since light is not generated by the light emitting element LD4, a voltage is not generated by the light receiving element PD3 of the third light receiving portion PR3. Furthermore, the NPN transistor TR 33 of the third light receiving portion PR3 is turned off to bring the D- data terminal P 13 of the first transceiver 301 into a floating state. That is, a logic low D- signal is output through the D- data terminal P 13 of the first transceiver 101. Here, the NPN transistor TR 32 of the third control switching portion CS3 is turned off, so that the third light emitting portion LE3 cannot operate normally. Industrial Applicability As described above, the USB connecting apparatus according to the present invention provides for an optical communication by the D+ and D- optical communication modules, thereby increasing communication speed and effective communication distance, removing electrical noise, and minimizing the difference in impedances between D+ and D- communication lines. While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein.

Claims: 5 What is claimed is: 1. A Universal Serial Bus (USB) connecting apparatus for interconnecting first and second transceivers for USB, the apparatus comprising: a D+ optical communication module connected between D+ data o terminals of the transceivers for converting a D+ electrical signal from the D+ data terminal of the first or second transceiver into a D+ optical signal and transmitting the D+ optical signal, and restoring the transmitted D+ optical signal to a D+ electrical signal and inputting the D+ electrical signal to the D+ data terminal of the second or first transceiver; s a D- optical communication module connected between D- data terminals of the transceivers for converting a D- electrical signal from the D- data terminal of the first or second transceiver into a D- optical signal and transmitting the D- optical signal, and restoring the transmitted D- optical signal to a D- electrical signal and inputting the D- electrical signal 0 to the D- data terminal of the second or first transceiver; a first electrical line connected between power-voltage terminals of the transceivers; and a second electrical line connected between ground terminals of the transceivers. 5 2. The apparatus of claim 1 , wherein the D+ optical communication module comprises: a first light emitting portion that converts a D+ electrical signal from the D+ data terminal of the first transceiver into a D+ optical signal; o a first optical fiber line that transmits the D+ optical signal from the first light emitting portion to the second transceiver; a second light receiving portion that restores the D+ optical signal from the first optical fiber line to a D+ electrical signal and inputs the restored D+ electrical signal to the D+ data terminal of the second 5 transceiver; 5 a second light emitting portion that converts a D+ electrical signal from the D+ data terminal of the second transceiver into a D+ optical signal; a second optical fiber line that transmits the D+ optical signal from the second light emitting portion to the first transceiver; and a first light receiving portion that restores the D+ optical signal from 0 the second optical fiber line to a D+ electrical signal and inputs the restored D+ electrical signal to the D+ terminal of the first transceiver. 3. The apparatus of claim 2, wherein in the D+ optical communication module, light is transmitted through the first or second s optical fiber line only when the D+ electrical signal from the D+ data terminal of the first or second transceiver is in a logic low state. 4. The apparatus of claim 3, wherein the D+ optical communication module further comprises: 0 a first control switching portion that prevents the first light emitting portion from operating only when light is transmitted through the second optical fiber line, and a second control switching portion that prevents the second light emitting portion from operating only when light is transmitted through the 5 first optical fiber line. 5. The apparatus of claim 1 , wherein the D- optical communication module comprises: a third light emitting portion that converts a D- electrical signal from o the D- data terminal of the first transceiver into a D- optical signal; a third optical fiber line that transmits the D- optical signal from the third light emitting portion to the second transceiver; a fourth light receiving portion that restores the D- optical signal from the third optical fiber line to a D- electrical signal and inputs the restored D- 5 electrical signal to the D- data terminal of the second transceiver; a fourth light emitting portion that converts a D- electrical signal frofn the D- data terminal of the second transceiver into a D- optical signal; a fourth optical fiber line that transmits the D- optical signal from the fourth light emitting portion to the first transceiver; and a third light receiving portion that restores the D- optical signal from the fourth optical fiber line to a D- electrical signal and inputs the restored D- electrical signal to the D- terminal of the first transceiver. 6. The apparatus of claim 5, wherein in the D- optical communication module, light is transmitted through the first or second optical fiber line only when the D- electrical signal from the D- data terminal of the first or second transceiver is in a logic high state. 7. The apparatus of claim 6, wherein the D+ optical communication module further comprises: a third control switching portion that prevents the third light emitting portion from operating only when light is transmitted through the fourth optical fiber line, and a fourth control switching portion that prevents the third light emitting portion from operating only when light is transmitted through the third optical fiber line.

Inventors: JUNG WON-SEOK, KIM IL, LEE KUM-HEE, SHIN HYUN-KUK, JUNG, WON-SEOK, KIM, IL, LEE, KUM-HEE, SHIN, HYUN-KUK
Applicants: JUNG WON SEOK, KIM IL, LEE KUM HEE, OPTICIS CO LTD, SHIN HYUN KUK, JUNG, WON-SEOK, KIM, IL, LEE, KUM-HEE, OPTICIS CO., LTD., SHIN, HYUN-KUK
Application year: 2001
Main classification: G06F13
IPC codes: G06F13, H04B10