JPS63300638A - Full duplex data transmitter - Google Patents

Abstract

PURPOSE:To attain a small-sized and inexpensive transmitter by inhibiting the reception of light to itself while its own pulse is projected and using a different modulation frequency to each projector, thereby eliminating the need for a processing circuit preventing a malfunction due to reflection. CONSTITUTION:The frequencies of a pulse oscillation circuit 12 of two transmission/reception units 111, 112 are deviated slightly by intension. As a result, projection signals P1, P2 emitted from opposed light emitting elements 14 are overlapped by one pulse at every period and parted completely in other time zone. In sending the H state to the opposite side by the units 111, 112, the pulse light modulated by the frequency is sent and in sending the L state, the element is not lighted. When the signals P1, P2 are sent mutually, the output of each photodetector 15 is given to detection circuit 18 only when an analog switch 17 is not nonconductive by inhibition signals F1, F2 from its own projector A. When the signals P1, P2 are overlapped, the pulse output is only missing and the light reception signal obtained from the incidence of the pulse light from the opposite party is all inputted to the circuit 18.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a full-duplex data transmission device that performs optical communication of 1-bit data using a simplified circuit.

Conventionally, an optical data transmission device (1) has been used for traffic control, cargo handling control, etc. of unmanned vehicles. As shown in Figure 5, this includes an unmanned vehicle (2), an intersection (3) where it travels, and a cargo handling area W.
(4), and is used to give an instruction to the unmanned vehicle (2) in which direction to turn, and to give an instruction to perform or prohibit cargo handling.

Such an optical data transmission device (1) can achieve its purpose even with half-duplex data transmission.

However, in the case of half-duplex, since the transmission direction is alternately switched, problems may arise in terms of responsiveness. Further, there are some inconveniences in use, such as the need for a separate holding circuit and switching circuit for the transmitted data.

Therefore, if it is desired to improve responsiveness and simplify peripheral circuitry, a full-duplex data transmission device must be used.

(5) (5) Full-duplex optical data transmission is a transmitting/receiving unit equipped with an emitter and a receiver, respectively, as shown in Figure 6.
facing each other and transmitting and receiving at the same time.

However, in this case, the pulsed light emitted by the own emitter (6) hits the case of the other party's transmitting/receiving unit or the surrounding equipment and is reflected, entering the own receiver (7) and causing malfunction. . The incidence of this reflected light is unavoidable because a light projector and a light receiver are arranged close to each other in one transmitting/receiving unit, and the light projecting and receiving angle is set large so that a moving unmanned vehicle can be detected.

As one means for preventing malfunctions caused by this reflected light, it is conceivable to connect the opposing transmitter/receiver units with a synchronization signal line and allow the light receiving operation to occur only when the other party's pulsed light is generated. However, it cannot be wired to moving unmanned vehicles and cannot be used.

As another preventive measure, it may be possible to vary the frequency of the pulsed light emitted by each transmitting/receiving unit and selectively extract only the pulsed light sent from the other party's power from the output of each light receiver.

However, in this case, since the received light signal is a combination of pulse signals with different frequencies, it is difficult to distinguish between them, and the processing circuit becomes considerably complicated, resulting in an expensive and large data transmission device.

In order to solve the above-mentioned problems, the full-duplex data transmission device provided by the present invention has the following features: Transmits and demodulates modulated light to become “H” or “L”
This device mutually transmits the state of the pulsed light, and is characterized in that its own pulsed light projector prohibits its own light reception, and at the same time, the modulation frequency of each projector is made different.

In the above means, each transmitter/receiver unit is set to “H”.
At the moment when each pulse of modulated light indicating the state is being transmitted, the pulse light emitted from the other party is not accepted. This eliminates malfunctions caused by reflected light.

When the light receiver of each transmitting/receiving unit receives pulse input of modulated pulsed light from the other party continuously in nfvA (however, omission of one shot is allowed), it is determined to be in the "H" state and outputs it.

The change from determination of the "H" state to determination of the "L" state occurs after a predetermined period of time has elapsed since the pulse input ceased.

Note that the above-mentioned pulse omission will not occur two or more times in a row if the frequency of each modulated pulse light is shifted appropriately. Therefore, there is no operational problem.

Ura-masu The present invention will be described below with reference to one embodiment.

FIG. 1 shows a full-duplex data transmission device (10) of the present invention.
1i warehouse diagram, and the opposing transmitting/receiving unit (111) (
112) has one emitter A and one receiver B,
Each light projector A supplies its own light receiver B with prohibition signals F1 and F2 that prohibit light reception at the timing of the pulsed light emission.

An example of the configuration of one transmitting/receiving unit (lh) (112) is shown in FIG. The projector A has a pulse oscillation circuit (12
), current amplification circuit (13), and light emitting diode (
It is composed of a light projecting element (14) such as an LED. In addition, the light receiver B includes a light receiving element (15) such as a photodiode,
Augmentation circuit (16), Ana.

It consists of a switching switch (17), a detection circuit (18), and an output circuit (19). Here, the above prohibition signal F
1 and F2 are the outputs of the current amplification circuit (13), which are supplied to the analog switch (17) as non-conductive signals.

The full-duplex data transmission device shown in Figures 1 and 2 above (
The operation 10) will be explained.

The frequencies of the pulse oscillation circuits (12) (12) of the two transmitter/receiver units (lb) (112) are intentionally slightly shifted. As a result, as shown in Figure 3,
The light projection signals pl and P2 emitted by the two opposing light projection elements (14) and (14) overlap by one shot at each predetermined period, and are completely separated during other time periods.

Each transmitter/receiver unit (111) (112) transmits pulsed light modulated at this frequency when transmitting an "H" state to the other party, and does not emit light when transmitting an "L" state to the other party. .

When the modulated pulsed lights P1 and p2 are mutually transmitted, the output of each light receiving element (15) (15) is turned off when the analog switch (17) is turned off by the prohibition signals F, -F2 from its own projector A. The detection circuit (1
8). Therefore, the two light projection signals P1 and F2
When the pulsed light is overlapped (indicated by arrow A in FIG. 3), the pulse output is only lost, and the received light signal obtained by the incidence of the pulsed light from the other party is all input to the detection circuit (18). When the detection circuit (18) receives n (for example, 19) light reception signals consecutively, it outputs the signal as having changed to the "H" state, and when a predetermined period of time has elapsed without any light reception signal being input, it outputs the "L" state. ,” is output as the state has changed. Here, the detection circuit (18) regards the light reception signal as a normal light reception signal if there is only one omission in the light reception signal, and continues counting by delaying the count by one. On the other hand, if two or more pulses are missing, the n counting is cleared to O and counting is restarted from the next light reception signal.

As mentioned above, each transmitter/receiver unit (lit) (11
2) transmits and receives data, as shown in FIG. 4, modulated light p! indicating the "H" state is emitted from one transmitting/receiving unit (lh) (112). , p.

is the other transmitting/receiving unit (112) (llt)
Then, with a slight delay d, the signal is transmitted as a reception output indicating the "H" state. In FIG. 4, the delay in the rise of the "H" state is the time for the detection circuit (18) to perform n counts, and the delay in the fall to the "L" state is the time for the detection circuit (18) to perform n counts. This corresponds to the no-signal state determination time set in (18).

Note that the detection circuit (18) may be one that detects the presence or absence of continuous pulse input, and the conditions for determining the falling edge and falling edge may be set to be different from those in the above embodiments.

The present invention intentionally slightly shifts the modulated optical frequency of the transmitter/receiver unit, and when the own projector is projecting pulsed light, the I
With a VI vehicle configuration, it is possible to realize a full-duplex optical communication system data transmission device.

Further, since a complicated processing circuit for preventing malfunctions caused by reflected light is not required, a compact and low-cost device can be provided.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram of the full-duplex data transmission device of the present invention;
FIG. 1 is a block diagram showing the configuration of a transmitting/receiving unit of the apparatus shown in FIG. Figures 3 and 4 are diagrams showing the operation timing of the device shown in Figures 1 and 2. Figure 3 is a relationship diagram of the light projection signal, prohibition signal, and light reception signal, and Figure 4 is the light projection signal. FIG. FIG. 5 is a schematic diagram of a traffic control system showing an example of the use of a full-duplex data transmission device, and FIG. 6 is a diagram illustrating problems in the conventional full-duplex data transmission device. (10) - full-duplex data transmission device, (l11) (112) - transmitting and receiving unit, A - projector, B - projector, Fl, F2 - inhibition signal.

Claims (1)

[Claims] (1) A device that transmits and demodulates modulated light between a pair of transmitting/receiving units each equipped with a projector and a receiver, and mutually transmits an "H" or "L" state, and the self-pulse A full-duplex data transmission device characterized in that the light projectors prohibit their own light reception and at the same time have different modulation frequencies for each light projector.