JP3186819B2 - Optical communication device and optical communication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical communication device and an optical communication method used for an optical remote control device, an optical fiber cable transmission device or an optical space transmission device.

[0002]

2. Description of the Related Art For example, in an optical remote controller, data is transmitted by modulating light by a pulse position modulation method, and the configuration thereof is generally as shown in FIG.
That is, in the optical signal transmitting section (1), an oscillation signal of a predetermined frequency as shown in FIG. 5A is input to one input terminal (A) of the AND gate circuit (A1), and the other input terminal is used. 5B, a pulse train signal whose pulse width is t as shown in FIG. 5B and whose time interval is a combination of t and 3t to binarize data is input, and this oscillation signal and pulse train signal are inputted. The switching transistor (Q1) is turned on / off by the logical product signal of the light-emitting element (L1) and the light-emitting element (L
D) is driven to blink, and the light-emitting element (LD)
An optical signal as shown in (c) is transmitted.

The oscillating signal has a fixed period of 1 / f as shown in FIG. 5 (d) showing an enlarged optical signal, and the pulse train signal has a data "0" as shown in FIG. 5 (b). Is a combination of a pulse having a pulse width of t and a time interval of t, and data "1" is a signal obtained by binarizing information using a combination of a pulse having a pulse width of t and a time interval of 3t.
Therefore, the light emitting element (LD) emits light intermittently at a period of 1 / f and a constant light intensity of i for a fixed time of t based on a logical product signal of the oscillation signal and the pulse train signal. This intermittent light emission is continuously repeated at a time interval of either t or 3t, and an optical signal as shown in FIG. 5C is output.

On the other hand, in the optical signal receiving section (2) shown in FIG. 1, a light receiving element (FD) including a photodiode or the like receives an optical signal from the optical signal transmitting section (1), and FIG. After converting the electric signal into an electric signal as shown in the figure, amplifying the electric signal with an amplifier (3), removing a DC component from the electric signal through a capacitor (4), and further using a bandpass filter (5), an optical signal transmitting unit (1) 2) passes only the component of the frequency f, and removes noise components due to disturbance light or the like. Subsequently, an electric signal having a waveform as shown in FIG. 6B output from the band-pass filter (5) is branched into two systems, one of which is directly input to the non-inverting input terminal (+) of the comparator (7). And the other is supplied to an integrating circuit (6) comprising a resistor (R) and a capacitor (C),
Since the time constant of the integrating circuit (6) is set to be longer than the time t, the integrated signal has a waveform of the average value of the received light signal as shown in FIG. It is input to the inverting input terminal (-) of (7). In the comparator (7), the electric signal input to the non-inverting input terminal (+) is converted to the inverting input terminal (-).
The electric signal is detected by comparing the average value signal input to the reference signal as a reference signal, and further integrated by a capacitor (8) to remove the component of the frequency f as shown in FIG. Converted to a signal. This integrated signal is
After the waveform is shaped by a hysteresis comparator (9) having a threshold of a high level of V _TH and a low level of V _TL indicated by a broken line in FIG. 6 (d), a transistor (Q2) and a pull-up resistor (10) are used. The signal is inverted, and a signal having a waveform as shown in FIG. 6E is output from the output terminal (O).

[0005]

However, in the above-described optical communication device, the time constant of the integrating circuit (6) is set to the time t in order to prevent malfunction due to noise due to disturbance light or the like.
Is set so that the voltage as the reference signal input to the inverting input terminal (-) of the comparator (7) gradually increases. Therefore, when data "1" continues in the optical signal, The potential of the integration signal from the integration circuit (6) decreases as shown by E in FIG.
Conversely, if data "0" continues, the integration circuit (6)
The potential of the integration signal from rises as shown by D in FIG. Therefore, the operating point of the comparator (7) fluctuates according to the arrangement of the data "1" and "0", and the output waveform of the capacitor (8) becomes
When the input potential of the inverting input terminal (-) of the comparator (7) is low, it rises quickly and the output waveform of the hysteresis comparator (9) also rises quickly, but the input potential of the inverting input terminal (-) of the comparator (7) is high. In some cases, the rise is delayed and a problem such as not reaching the high level _VTH occurs as shown by F in FIG.
In (e), a signal having a large pulse width as indicated by G is output. As described above, the pulse width of the output waveform of the optical signal receiving unit (2) is apt to change due to the arrangement of the data “1” and “0”, so that it becomes impossible to determine the transmission data.

Therefore, according to the present invention, the potential of the reference signal of the detection comparator of the optical signal receiving section is always kept constant irrespective of the arrangement of the data "1" and "0" to accurately restore the binary original signal. An object of the present invention is to provide an optical communication device and an optical communication method that can be used.

[0007]

According to the present invention, an optical communication apparatus is constituted as follows as technical means for achieving the above-mentioned object. That is, Rutotomo the light emission element to and a predetermined intensity intermittently for a predetermined time for light emission of the light at a constant period
To, the time interval until the intermittently emitting the light emitting element 2 kinds provided, an optical signal transmission unit to be transmitted as an optical signal of the binary signal data by the pulse position modulation by Rukoto combination of the two types of time intervals , means for converting an optical signal received into an electric signal, means for detecting the electric signal the electrical signal obtained by integrating the reference signal and compared to the signal waveform shaping to binary obtained by integrating the detection signal hand be restored to the original signal of
In the optical communication system consisting of an optical signal receiving unit having steps, the optical signal transmitting unit intermittently intensity of the emitted to light for a predetermined time said light emitting element at a constant cycle, then intermittently light emitting element It is characterized in that transmission is performed by setting the value to a value proportional to the time interval until a specific light emission.
Further, the present invention provides a technical solution for achieving the above object.
As a means, the following optical communication method was adopted. That is, Koshin
In the signal transmission section, the light emitting element is
To emit light intermittently for a certain time at the intensity of
Two types of time intervals until the light emitting element emits light intermittently
By combining these two time intervals
Data as optical signal of binary signal by pulse position modulation
Transmit and convert the optical signal to an electrical signal in the optical signal receiving unit.
The electric signal is replaced with a reference signal obtained by integrating the electric signal.
Comparing and detecting with a comparator, integrating this detected signal
Optical communication method for waveform shaping of restored signal to restore to binary original signal
In the method, the light emitting element is interrupted for a certain period of time at a certain cycle.
The intensity of the light to be emitted continuously, and then the light emitting element
To a value proportional to the time interval
It is characterized by.

[0008]

From the optical signal transmitting unit, for example, when data "0" is set to a duration of t where the light intensity is i and the light intensity is zero, the data "1" is converted to the light intensity of 3i. In addition, since an optical signal whose duration is set to 3t at which the light intensity is zero is transmitted, the signal obtained by integrating the electric signal obtained by photoelectrically converting the optical signal in the optical signal receiving unit becomes a signal having the light intensity of zero. In the case of data “0” having a short duration t, the light intensity is also small as i, so that the data does not increase to a certain value or more. In the case of 1 ", the light intensity does not drop below a certain value because the light intensity is correspondingly large at 3i. That is, since the integration signal of the electric signal, that is, the reference signal of the detection comparator is held substantially constant, the operating point of the comparator becomes substantially constant, and the pulse width of the output waveform corresponds to the transmission data. The original binary signal can be accurately restored.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a block configuration of an embodiment of the present invention. In FIG. 1, the same or equivalent components as those in FIG. 4 are denoted by the same reference numerals. An AND gate circuit ( A ) that connects another switching transistor (Q3) in parallel to the existing switching transistor (Q1) and controls the switching of the switching transistor (Q3).
2) providing inputs the output signal of the existing AND gate (A1) to one input terminal of the AND gate (A2), the other input terminal, the data as shown in FIG. 2 (d) Corresponding to "0" and "1", when data is "0", it is "0" low level and when data is "1", it is "1".
The only difference is that a configuration for inputting a high-level signal is added.

Next, the operation of the above embodiment will be described with reference to the optical signal transmitting unit (1).
This will be described in detail with reference to FIG. 2 showing the timing chart of 1) and FIG. 3 showing the timing chart of the optical signal receiving section (2). 2A and 2B show waveforms of input signals at both input terminals (A) and (B) of the AND gate circuit (A1), respectively. FIG. 2C shows the waveform of the AND gate circuit (A1).
FIG. 3D shows the waveform of the output signal of the AND gate circuit (A2) as described above.
2 shows a waveform of an input signal to the LM. Therefore, the switching of the switching transistor (Q1) is controlled by the output signal of the AND gate circuit (A1) shown in FIG.
Switching control is performed by a signal obtained by logically ANDing the signal of (c) and the signal of (d) in the same figure by an age gate circuit (A2). Therefore, from the light emitting element (LD), FIG.
As shown in (e), when the data is “0”, an optical signal in which the light intensity repeats “0” and “i” at a constant cycle 1 / f in response to the switching operation of the switching transistor (Q1) is time-dependent. t, and when the data is “1”, the light intensity changes between “0” and “3i” at a constant period of 1 in accordance with each switching operation of the switching transistor (Q1) and the switching transistor (Q2). An optical signal that repeats at / f is output during time t. That is, from the optical signal transmission unit (11), the intensity of light for causing the light emitting element (LD) to emit light intermittently at a constant period (1 / f) for a constant time (t) is then changed to the light emitting element (LD). An optical signal set to a value i or 3i proportional to the time interval (t) or (3t) until intermittent light emission is output.

Then, in the optical signal receiving section (2), the light receiving element (FD) receives the optical signal and converts it into an electric signal as shown in FIG. 3 (a), and the electric signal is converted by the amplifier (3). After amplification, the DC component is removed by the capacitor (4), and the signal passed through the band-pass filter (5) is shown in FIG.
The waveform becomes as shown in (b), and this electric signal is input to the non-inverting input terminal (+) of the comparator (7). On the other hand, a signal obtained by integrating this electric signal by the integration circuit (6) is
When the light intensity is zero and the data is "0" having a short duration t, the light intensity is correspondingly small at i, so that the light intensity does not rise to a certain value or more, while the light intensity is zero. Is 3t, which is a long data “1”, the light intensity is also 3
It does not fall below a certain value because it is large as i. That is, the integration signal output from the integration circuit (6) is held at a substantially constant value as shown in FIG. 3 (c), and this integration signal is supplied to the inverting input terminal (-) as a reference signal of the comparator (7). Since the input is input, the operating point of the comparator (7) becomes substantially constant, and the signal obtained by integrating the output signal of the comparator (7) with the capacitor (8) has a waveform as shown in FIG. The output signal from O) is shown in FIG.
As shown in (2), the waveform has a pulse width corresponding to the transmission data, and the binary original signal can be accurately restored.

[0012]

Optical communication devices and the present invention as described above, according to the present invention
According to the optical communication method , the optical signal transmitting unit sets the intensity of light that causes the light emitting element to emit light intermittently at a constant period for a certain time period, a value proportional to a time interval until the next light emitting element emits light intermittently. since so as to set, in the optical signal receiving unit, since the reference signal of the integration signal, i.e. detection comparator of the received electrical signals can be kept substantially constant irrespective of the received data, the operating point of the comparator is substantially constant The pulse width of the output waveform corresponds to the transmission data,
It can be accurately restored to a binary original signal.

[Brief description of the drawings]

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

FIG. 2 is a timing chart of signals of each unit of the optical signal transmission unit according to the first embodiment.

FIG. 3 is a timing chart of signals of respective units of the optical signal receiving unit according to the first embodiment.

FIG. 4 is a block diagram of a conventional optical communication device.

FIG. 5 is a timing chart of signals of respective units of the optical signal transmission unit according to the first embodiment.

FIG. 6 is a timing chart of signals of respective units of the optical signal receiving unit according to the first embodiment.

[Explanation of symbols]

 2 Optical signal receiving unit 6 Integrating circuit 7 Detection comparator LD Light emitting element 11 Optical signal transmitting unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ identification code FI H04B 10/26 10/28 (58) Fields investigated (Int.Cl. ⁷ , DB name) H04B 10/00-10/28 H04J 14/00-14/08 H03K 7/04 H04Q 9/14 H04L 27/00-27/30 H04L 25/00-25/66

Claims (2)

(57) [Claims] 1. A Luminous element causes a constant period at and given the intensity of the light intermittently emit light during the predetermined time Rutotomoni, provided two time intervals until the intermittently emitting the light emitting element, the means for converting the optical signal transmitting unit that transmits data by Rukoto combination of two time intervals as the optical signal of the binary signal by pulse position modulation, the optical signal received into an electrical signal, the electrical and the electrical signal means for detecting signals obtained by integrating the reference signal and compared to the, having a means for restoring the integrated signal to the detection signal to the original signal waveform shaping to binary
In the optical communication system consisting of an optical signal receiving unit that, the optical signal transmitting unit intermittently intensity of the emitted to light for a predetermined time said light emitting element at a constant cycle, then intermittently the light emitting element set to a value which is proportional to the time interval until the emission is
An optical communication device for transmitting . 2. A light emitting element is fixed in an optical signal transmitting section.
Light emission intermittently for a certain period of time and at a predetermined light intensity
Until the light-emitting element emits light intermittently.
Two types of time intervals are provided, and these two types of time intervals are combined.
By combining, the data is binary by pulse position modulation
The optical signal is transmitted as an optical signal.
Convert the signal to an electrical signal and convert the electrical signal to an electrical signal
The integrated reference signal is compared with a comparator and detected.
Waveform of the signal obtained by integrating the detection signal of
In the optical communication method for restoring to a predetermined
The intensity of the light emitted intermittently for a certain period of time
Proportional to the time interval until the light-emitting element emits light intermittently
An optical communication method characterized in that the value is set to a predetermined value.