JPH0530031A - Optical communication equipment - Google Patents

Abstract

PURPOSE:To obtain a wide communication margin by implementing automatically the control that a transmission level is increased when a duty measured by a receiver side is less than a reference value and the transmission level is lowered when the duty is in excess of the reference value. CONSTITUTION:An optical output control section 11 changes a level of an optical signal outputted from a light emitting diode 12 in response to the attribute of a given control signal to a high level or a low level by a prescribed width each. Then the reception section 20 includes a duty detection section 24 which compares the duty of a waveform of an electric signal shaped by a waveform shaping section 22 with a reference value and generates a control signal with an attribute corresponding to the relation of quantity being the result of comparison and given to an optical output control section 11 of a transmission section 10. In this case, the transmission section 10 outputs a rectangular wave whose duty is 50%. When the duty is less than 50% at the receiver side, the control signal to increase the optical output is sent to the sender side and when less than 50%, the optical output is decreased.

Description

Detailed Description of the Invention

[0001]

The present invention is used in optical communication systems. In particular, it relates to an optical communication device using a light emitting diode and a phototransistor.

[0002]

2. Description of the Related Art In a conventional example, a transmitter and a receiver communicate with each other as independent devices. As shown in FIG. 2, the device has both a transmitter and a receiver, and each unit has a plurality of sets of the light emitting diode 12 and the phototransistor 2.
Two-way communication is performed between the two. Here, the optical output of the transmitter is fixed to a constant value by the forward current control resistor 14, and the optical output of the light emitting diode 12 is fixed in the receiver.
The phototransistor 21 selected on the basis of data such as directivity receives light, and the waveform shaping section 22 at the subsequent stage performs signal reproduction.

[0003]

In such a conventional example, since the parameters of both the transmitting unit and the receiving unit are determined as constant values, communication is possible only within the allowable range of the parameters, and the light emitting diode. The allowable range is significantly narrowed due to the overlap of these parameters due to the directivity of the device, the amount of light output and its secular change, the directivity of the phototransistor, the sensitivity, the temperature dependence of both elements and their position shifts, etc. It was a factor that caused it.

The present invention eliminates such drawbacks, and an object of the present invention is to provide an optical communication device capable of ensuring an optimum communication state.

[0005]

According to the present invention, a light emitting diode and a transmitter including an optical output controller for controlling the level of an optical signal output by the light emitting diode, and an optical signal arriving from a transmitter of a partner device are provided. In an optical communication device including a receiving phototransistor and a receiving unit including a waveform shaping unit that shapes the waveform of an electric signal output by the phototransistor, the optical output control unit is configured to respond to an attribute of a given control signal. The receiving unit includes means for changing the level of the optical signal output by the light emitting diode in a high level or low level direction by a predetermined width, and the receiving unit has a duty of the waveform of the electric signal shaped by the waveform shaping unit as a reference value. A size comparison is performed, and a data signal having an attribute corresponding to the magnitude relationship which is the comparison result and generating a control signal to be supplied to the optical output control unit of the transmission unit of the partner device is generated. Characterized in that in that it comprises a Ti detector.

[0006]

When the duty value measured on the receiving side is lower than the reference value, the transmission level is increased, and when it is higher than the reference value, the transmission level is decreased. Thereby, a wide communication margin can be secured.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of this embodiment. In this embodiment, as shown in FIG. 1, a transmitter 1 including a light emitting diode 12 and an optical output controller 11 for controlling the level of an optical signal output by the light emitting diode 12.
0, a phototransistor 21 for receiving an optical signal coming from the light emitting diode 12 of the partner device, and a receiving section 20 including a waveform shaping section 22 for shaping the waveform of an electric signal output by the phototransistor 21, and further, a book As a feature of the present invention, the light output control unit 11 includes the light emitting diode 12 according to the attribute of a given control signal.
The receiving unit 20 includes means for changing the level of the optical signal output by the device in a high level or low level direction by a predetermined width.
The duty of the waveform of the electric signal shaped by the waveform shaping unit 22 is compared with a reference value in magnitude to have an attribute corresponding to the magnitude relationship as a result of this comparison, and the optical output control unit 11 of the transmission unit 10 of the partner device It includes a duty detection unit 24 that generates a given control signal.

Next, the operation of this embodiment will be described. Figure 3
Is a flow chart showing the operation of this embodiment. First, the transmitter 10 transmits a rectangular wave with a duty of 50%. Next, on the receiving side, the duty is checked after receiving this signal and shaping the waveform. Here, if the duty is 50% or less, a control signal is transmitted to the transmitting side so as to raise the optical output to a certain level, and if it is 50% or more, it is lowered. In this case, there is a possibility that the light emitting diode 23 for transmitting the control signal and the phototransistor 13 are not matched, so that the control signal is transmitted at the lowest baud rate. In addition, the forward current for adjusting the light output must not exceed the absolute maximum rating. By repeating this series of operations several times, the light output of the light emitting diode approaches the level at which a waveform with a duty of 50%, which is the most appropriate for the paired phototransistors, is emitted.

In addition, the present embodiment can be effective only when it is performed every time the optical communication is started. This is because, in an optical communication system using a light emitting diode and a phototransistor, first of all, there are elements having various parameters for each device, so the combinations are infinite. Secondly, the environment for optical communication becomes a problem. This is largely due to the temperature dependence of the device. Therefore, in order to perform proper optical communication including these factors, this embodiment must be performed every time optical communication is started.

[0010]

As described above, the present invention sets the optimum state between the transmission section and the reception section for each device every time communication is started. Therefore, the present invention is generated by the combination of the light emitting diode and the phototransistor. It is possible to eliminate most of the disturbing factors that occur, and there is also an effect that it is possible to cope with the decrease in the light output of the light emitting diode caused by aging.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a block configuration diagram showing a configuration of a conventional example.

FIG. 3 is a flowchart showing the operation of the embodiment of the present invention.

[Explanation of symbols]

 1 Optical Communication Device 2 Optical Communication Device 10 Transmitter 11 Optical Output Control Unit 12 Light Emitting Diode (LED) 13 Phototransistor (PTR) 14 Forward Current Control Resistor 20 Receiver 21 Phototransistor (PTR) 22 Waveform Shaper 23 Light Emitting Diode ( LED) 24 Duty detector

Claims (1)

Claim: What is claimed is: 1. A light-emitting diode and a transmitter including an optical output controller for controlling the level of an optical signal output by the light-emitting diode, and a photo that receives an optical signal coming from a transmitter of a partner device. In an optical communication device including a transistor and a receiving unit including a waveform shaping unit that shapes the waveform of an electric signal output by the phototransistor, the optical output control unit includes the light emission control unit according to an attribute of a given control signal. The receiving unit includes means for changing the level of the optical signal output from the diode in a high level or low level direction by a predetermined width, and the receiving unit compares the duty of the waveform of the electric signal shaped by the waveform shaping unit with a reference value. However, a duty cycle that has an attribute corresponding to the magnitude relationship that is the result of this comparison and that generates a control signal to be supplied to the optical output control section of the transmission section of the partner device. An optical communication device including a detection unit.