1 realization principle
This plan is one kind through the fiber optic transmission USB signal electric circuit, pairs the use, the transmitted light intensity three ranks (entire bright, half bright, dark) separately represents the USB data line three kind of conditions, when light intensity for lowest (is dark) leaves unused the condition on behalf of the USB data line. First transmits the USB signal one only then because its USB data condition first changes, its condition change has a drop through the fiber optic transmission opposite party electric circuit accepting circuit (along triggers a monostable circuit along or rise), this monostable circuit output controls the USB signal "to receive/sends" the permission. First transmits the USB signal one only then because its USB data condition first changes, its condition change has a drop through the fiber optic transmission opposite party electric circuit accepting circuit (along triggers a monostable circuit along or rise), this monostable circuit delay time is USB transmits data time.
2 concrete realizations methods
2.1 the USB signal (D+, D -) transforms into the fiber optic transmission signal
Chart 1
Chart 1 is the USB signal (D+, D-) transforms into the fiber optic transmission signal - laser diagram. The USB signal examination electric circuit (1) is "or" the gate outputs D+ and the D- transformation DOR1 and the difference comparator outputs RCV1. A pair of controllable 三� buffer (2) carries the EN control logic through the control "to pass" and "the end". When EN= "0", DOR=DOR1, RCV=RCV1. But when EN= "1", DOR and RCV are the high anti- condition. The laser transmission actuation electric circuit (3) DOR and the RCV transformation is three kind of lasers intensities (bright, half bright, is dark). The laser accepting circuit (4) will receive three kind of lasers intensities (bright, half bright, will be dark) restore will be D+ and the D- three kind of conditions. Laser accepting circuit (4) of a H outputs change of state touches the bill steady delay circuit (5). List steady delay circuit (5) output EN usually (namely the USB signal is in leaves unused when condition) is "0", when it inputs H to have the drop to extend (namely by "1" becomes "0") outputs EN by "0" to become "1" and the maintenance is "1" approximately 1000us, then restores is "0". Another pair of controllable 三� buffer (2) carries EN through the control to control the control logic "to pass" and "breaks", when EN= "1", VP=H, VM=L, but when EN= "0" outputs VP, VM is the high anti- condition.

2.2 transforms the USB signal for is advantageous for the fiber optic transmission circuit diagram
Chart 2 is transforms the USB signal for is advantageous for the fiber optic transmission circuit diagram. Supposition USB is the full speed condition (12M), this time D+ meets the +5V power source through probably the 1.5K Omega resistance. Usually the USB signal is at leaves unused (Idle) the condition, this time D+ is "1" (high level, about 3 to 5V), D- is the logic "0" (low level, about 0 to 1.4V). IC1 is "or" the gate. IC2, IC4, IC5 and IC6 are the controllable 三� buffer. Among them, IC2 and IC4 are when its control signal EN is "0" leads passes, but IC5 and IC6 are when its control signal EN is "1" leads passes. Because IC2 and IC4 when do not lead passes (namely EN is "1" when) outputs for the high anti- condition, therefore
Chart 2
Added in the IC2 out-port on has pulled resistance R1, added in the IC4 out-port on has pulled resistance R2. IC3, IC10 and IC11 are a comparator. IC7 is the list steadily triggers the electricity route input end (signal VP) to drop along triggers, outputs EN usually is "0". When the IC7 input end appears a drop along, its out-port will appear duration approximately 1000us "1" the condition, then will restore will be "0". IC7 output signal EN through controls IC2, IC4, IC5 and IC6 controls D+, D- "receives/sends" the condition. Because EN usually is "0", therefore usually allows to receive D+ and D- (IC2, IC4 leads passes), but forbids the transmission signal to on D+ and D- (IC5 and the IC6 output for Gao Zutai).

3 signals processing ways
Usually leaves unused the condition (Idle) when D+ is the logic "1", D- is the logic "0", therefore IC1, the IC2 output is "1", IC3, the IC4 output is "1", the output laser intensity is "is dark". When the laser intensity is "is dark", after opposite party electric circuit laser receiver and the process opposite party electric circuit IC9 output is VP= "1", VM= "0". Once USB starts to transmit the data, then D+ and the D- signal logic condition changes. The full speed USB signal change of state is: D+ by "1" turns is "0", D - by "0" turns is "1". On the position machine USB signal condition first appears the change, this time IC1 and the IC2 output still was "1", IC3 and the IC4 output turns is "0". The laser transmission diode by "dark" will turn will be "entire is bright". "Entire is bright" the laser passes to opposite party electric circuit laser receiving tube through the optical fiber. Opposite party electric circuit VP by "1" becomes "0", VM by "0" becomes "1". Opposite party electric circuit VP by "1" becomes "0" is said this VP has had a drop along, thus has triggered opposite party electric circuit IC7, causes IC7 output EN by "0" to become "1" and to maintain "1" probably 1000us (then also to restore is "0"). Opposite party electric circuit VM by "0" becomes "1" thus to cause opposite party electric circuit the USB signal (EN= "0") to become the prohibition receive by the prohibition transmission (EN= "1"). This time opposite party electric circuit VP and VM may bequeaths opposite party electric circuit through opposite party electric circuit IC5 and IC6 D+ and D-, thus enable the position machine USB signal to pass to opposite party electric circuit in 1000us through the optical fiber (namely: Lower position machine) D+ and D- on-line. In this 1000us may fiber optic transmission three kind of D+ and the D - condition: (1)th, D+ is "1" also D- is "0" (representative leaves unused condition as well as data "1") (2), D+ is "0" also D- is "1" (on behalf of data "0") (3), D+ is "0" also D- is "0" (represents data transmission end mark). These three kind of conditions may express the USB signal all conditions (D+ are "1" also D- are "1" condition is prohibition). In probably the 1000us time, on exactly the position machine finished to a lower position machine transmission USB data, and waiting lower position machine feedback answering signal. After 1000us had ended, lower position machine IC7 output EN restores is "0", this time the lower position machine USB data condition first changes. Is completely same the lower position machine USB data transmission to on position machine process on position machine USB data transmission which describes with front to the lower position machine process principle.

4 experiments and application
After the system design completes, according to the electric circuit in succession request, and may reappear the USB signal after the simulation debugging in the far-end. This electric circuit may use in outside each kind of USB to suppose, moreover does not change the original driver. Outside certain USB supposes at present not to have effectively to lengthen the plan, for instance USB mouse, after then uses this electric circuit to be allowed to be able to succeed the realization.
The present picture long-distance fiber optic transmission plan often needs the special hardware connection and special-purpose picture processing software, after but uses this plan the electric circuit, only must lengthen ordinary USB 摄像�?then realizes.

Reference
1 Chinese practical new patent: ZL02284434

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