JPH07202817A - Optical communication device - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize an optical communication device that communicates with an appropriate light intensity corresponding to the distance of the other party. [Structure] Luminous intensity setting circuit 19 of transceivers 12a and 12b
a and 19b set the luminous intensities of the light emission signals Lab and Lba in a plurality of (for example, 1 to 4) predetermined stages. Prior to the optical communication, the transmission side 12a transmits a reception status confirmation signal of a specific code at a minimum luminous intensity of 1 a predetermined number of times (for example, 4 times). The receiving side 12b transmits the response signal the same number of times as the number of times of reception with the luminous intensity corresponding to the number of times of receiving the reception state confirmation signal. The transmitting side 12a sets the luminosity to 1 if the number of transmissions of the reception status confirmation signal does not match the number of receptions of the response signal.
The number of transmissions is increased by one and the number of transmissions is reduced by one, and a reception confirmation signal is transmitted. In this way, if the numbers of times of sending and receiving the reception state confirmation signal and the response signal match, the luminous intensities of the light emission signals Lab and Lba used for optical communication are determined.

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 having a bidirectional communication function.

[0002]

2. Description of the Related Art Optical communication devices are mutually light emitting elements (light sources).
It is equipped with a light receiving element and sends light to the other party and receives light from the other party to communicate, and it is possible to transmit and receive wirelessly, not to be affected by electromagnetic disturbance, and to modulate the transmitting side. It is advantageous in that demodulation on the receiving side can be realized with a simple circuit configuration.

FIG. 6 is a block diagram showing the electrical configuration of an optical communication device according to the prior art. The optical communication device 1 includes at least a pair of transceivers 2a and 2b. For convenience of explanation, the two have the same configuration, and the blocks arranged symmetrically are distinguished by adding a and b to the reference symbols. One transceiver 2a includes a transmitter 3a and a receiver 4a. The transmitter 2a drives the light emitting element 4a, which is a light source, and sends an optical signal Lab to the transceiver 2b, which is the other party. For the light emitting element 4a, for example, a light emitting diode is used. Hereinafter, the light emitting element 4a (4b) may be referred to as a light emitting diode 4a (4b). Optical signal L sent out
Ab is received by the light receiving element 5b of the transceiver 2b, and the output of the light receiving element 5b is analyzed by the receiving unit 6b. Light receiving element 5
For example, a photodiode is used for b. Less than,
The light receiving element 5b (5a) may be referred to as a photodiode 5b (5a).

The optical signal Lba from the transmitter / receiver 2b to the transmitter / receiver 2a is also transmitted / received in the same procedure, and bidirectional communication is performed.

FIG. 7 is a waveform diagram showing signal waveforms used in optical communication. In optical communication, binary signals of "1" and "0" are used, and "1" is represented by turning on (on) the light emitting element and "0" by extinguishing (off). FIG. 7 (1) shows the waveform of the transmission signal a of 1, 0, 1, 0, ... Transmitted to the other party.

FIG. 7 (2) shows the waveform of the carrier wave b modulated by the transmission signal a. The carrier wave b is supplied from an oscillation circuit (not shown), and a high frequency signal having a cycle shorter than that of the transmission signal a is used.

By inputting the transmission signal a and the carrier wave b to the AND gate Q1 shown in FIG. 7 (4), the carrier wave signal c having the waveform shown in FIG. 8 (3) is output from the AND gate Q1. Is output. The high frequency modulated carrier signal c is used for optical communication in order to prevent malfunction due to external light.

FIG. 8 is a circuit diagram showing a part of a transmission circuit and a reception circuit of an optical communication device according to the prior art. In FIG. 8, parts corresponding to those in FIG. 6 are designated by the same reference numerals. A protective resistor R2 is provided on the anode of the light emitting diode 4a.
The power supply voltage Vca is applied via a. The cathode of the light emitting diode 4a is grounded via the transistor Q2a provided in the receiver 3a. Therefore, when the transistor Q2a turns on, the light emission current Isa
And the light emitting diode 4a emits light.

In the receiving section 3a, when the carrier signal c shown in FIG. 7 (3) is applied to the base of the transistor Q2a via the base resistor R1a, the transistor Q2 is turned on.
a turns on / off in response to the carrier signal c. The ON period of the transistor Q2a corresponds to "1" of the carrier signal c,
The light emitting diode 4a repeats blinking in the cycle of the carrier wave b. As a result, the high-frequency modulated light emission signal Lab is transmitted from the transmission unit 3a and is incident on the photodiode 5b provided in the reception unit 6b of the other party.

In the photodiode 5b, the conductivity changes according to the light emission signal Lab, and the light receiving current Irb proportional to the brightness of the incident light flows in the direction shown in the figure through the resistor R3b. Therefore, the light reception signal d obtained by inverting the light emission signal Lab is derived from the anode of the photodiode 5b. The received light signal d is amplified by the amplifier circuit 7b and then input to the demodulation circuit 8b realized by a narrow band filter or the like,
The demodulation signal e is output. The demodulated signal e is inverted by the inverting circuit realized by the transistor Q3d and the collector resistor R4b, and the reception signal a synchronized with the above-mentioned transmission signal a is derived from the collector. In this way, optical communication is performed from the transmitting unit 3a to the receiving unit 6b of the other party. In addition, by performing the above procedure in reverse, bidirectional communication between the pair of transceivers 2a and 2b is performed.

[0011]

The optical communication by radio is
The advantage is that no transmission means such as a cable is required, but the reach distance is limited because the light emitted into the space is diffused. Also, the brightness of the light (illuminance) at the light receiving location
Is proportional to the brightness (luminosity) of the light source and inversely proportional to the distance according to the inverse square law, and therefore, as shown in FIG. 9A, for example, as shown in FIG. The illuminance is 4: 1 at the light receiving position c at the double distance 2a.
That is, the luminous intensity at the light receiving position b may be one fourth of the luminous intensity at the light receiving position c. When the light source is a light emitting diode, the luminous intensity is proportional to the driving current of the light emitting diode.

However, in the above-mentioned conventional optical communication device, the maximum communication distance is set, and a drive current corresponding to the maximum communication distance is supplied to the light emitting diode to emit light with a constant luminous intensity. Therefore, assuming that the set distance is the distance 2a shown in FIG. 9A, three-fourths of the electric power is wasted when transmitting to the light receiving position b which is half the distance. There was a problem. On the other hand, when transmitting over a double distance, four times the electric power is required, and in the case of a portable device used outdoors, there is a problem that the battery capacity increases and it is against size and weight.

Further, as shown in FIG. 9B, 2
When the two light receiving positions a and b are at a close distance Δa, the light receiving amount at the light receiving position d becomes excessive under the constant light intensity as described above, the light receiving element such as a photodiode is saturated, and the light source is turned off. Even so, a current still flows through the light receiving element for a while, which causes a problem that the light receiving element is erroneously recognized as being in a receiving state.

These problems are caused by setting the luminous intensity constant in consideration of the maximum reachable distance of the optical communication device.

Therefore, an object of the present invention is to solve the above-mentioned problems and to provide an optical communication device which realizes a good communication state by changing the light emission intensity according to the distance to the other party.

[0016]

According to the present invention, in an optical transmitter for converting an electric signal into an optical signal and transmitting the optical signal to a receiver for optical communication, the luminous intensity of the optical signal to be transmitted is set to a plurality of steps. Light intensity setting means, confirmation signal generating means for generating a predetermined reception state confirmation signal to be transmitted to the receiving device side prior to communication, and receiving a predetermined reception state determination signal transmitted from the receiving device side. An optical transmitter comprising: a light intensity control unit that instructs the light intensity setting unit to perform a light intensity setting step based on a reception state determination signal.

Further, according to the present invention, in an optical receiving device for receiving an optical signal sent from the transmitting device side and converting it into an electric signal, a predetermined reception state confirmation signal sent from the transmitting device prior to communication is sent. An optical receiving apparatus comprising: a reception state determination means for receiving and determining its own reception state; and a determination signal generation means for generating a reception state determination signal based on the determination result of the reception state determination means. is there.

The present invention also provides an optical transmitter for converting an electrical signal into an optical signal and transmitting the optical signal to the receiver, and an optical receiver for receiving an optical signal sent from the optical transmitter and converting it into an electrical signal. In the optical communication device comprising, the optical transmission device, a luminous intensity setting means for setting the luminous intensity of the optical signal to be transmitted in a plurality of stages, and a predetermined reception state confirmation signal to be sent to the receiving device side prior to communication. A confirmation signal generation means for generating and a predetermined reception state determination signal sent from the receiving device side, and a light intensity control means for instructing the light intensity setting means to perform a light intensity setting step based on the reception state determination signal. The optical receiving device receives a predetermined reception state confirmation signal sent from the transmission device prior to communication, and determines reception state determining means for receiving itself, Based on the determination result of the state determining means, a optical communication device characterized by including a discrimination signal generating means for generating a discrimination signal.

[0019]

The optical communication device according to the present invention comprises an optical transmitter for converting an electric signal into an optical signal for optical communication, and an optical receiver for receiving the optical signal and converting it into an electric signal.

The optical transmitter includes a luminous intensity setting means, a confirmation signal generating means, and a luminous intensity control means, and the luminous intensity setting means comprises:
The luminosity of the optical signal to be transmitted is set in a plurality of stages, and the reception state confirmation signal generated by the confirmation signal generation means is sent to the optical receiving device prior to communication.

The optical receiving device receives the reception state confirmation signal sent from the optical transmitting device prior to the communication, and when the reception state discriminating means discriminates the reception state, the reception state discriminating signal generating means determines the receiving state discriminating means. A reception state determination signal is generated based on the determination result.

When the optical transmitter receives the reception state discrimination signal, the luminous intensity control means instructs the luminous intensity setting step based on the discrimination signal, and the luminous intensity of the optical signal to be sent to the optical receiver is set. As a result, the luminous intensity of the optical signal used for the optical communication between the optical transmitter and the optical receiver is set according to the actual situation.

[0023]

1 is a block diagram showing the electrical construction of an optical communication apparatus according to an embodiment of the present invention. Optical communication device 11
Is composed of at least a pair of transceivers 12a and 12b. Since the transceivers 12a and 12b have the same configuration, only one transceiver 12a will be described. Transceiver 12a
Includes a transmission circuit 13a which is a transmission means, a reception circuit 14a which is a reception means, an operation unit and a power supply circuit which are not shown.

The transmission circuit 13a is composed of the following blocks.

Light emitting diode 15a (15b), AND
Gate Q11a (Q11b), transistor Q12a
(Q12b), luminous intensity setting circuit 19a (19b), luminous intensity selecting circuit 20a (20b), timer 21a (21b), signal generating circuit 23a (23b), oscillator circuit 24a (24).
b).

The receiving circuit 14a is composed of the following blocks.

Photodiode (light receiving element) 16a (16
b), amplification circuit 17a (17b), demodulation circuit 18a (1
8b), a transistor Q13a (Q13b), and a reception confirmation circuit 22a (22b).

The structure of the transmission circuit 13a will be described.
The transmission signal a from the signal generation circuit 23a and the carrier wave b from the oscillation circuit 24a are input to the AND gate Q11a forming the modulation circuit, and the AND gate Q11a is input.
From, the carrier signal c is derived as shown in FIG. 8 and applied to the base of the transistor Q12a.
The signal generation circuit 23a generates and outputs a reception state confirmation signal for confirming the reception state between the devices, in addition to the transmission signal used for optical communication. The confirmation signal includes, for example, “55H” (0101010) for easy identification.
A code in which 1,0 as in 1) is regularly arranged is selected.

The transistor Q12a forms a switch circuit, and is in the ON state while the carrier signal c is "1" as shown in FIG. 8 and is in the OFF state when it is "0". The power supply voltage Vc is applied to the collector of the transistor Q12a via the series circuit of the light emitting diode 15a and the light intensity setting circuit 19a. When the transistor Q12a is in the ON state, the current Isa flows and the light emitting diode 1
5a emits light. The luminous intensity of the light emitting diode 15a is proportional to the magnitude of the current Isa.

It should be noted in the present invention that the luminous intensity setting circuit 19a, which is a luminous intensity setting means for setting the luminous intensity of the light emitting diode 15a in plural stages, and the luminous intensity control for instructing the luminous intensity setting circuit 19a to the luminous intensity setting stage. The light intensity selection circuit 20a as a means is provided to change the light intensity of the light emitting diode 14a in a plurality of steps.
These operations will be described later.

Next, the structure of the receiving circuit 14a will be described. The photodiode 16a receives the incident light emission signal L
The conductivity changes depending on ba, and the light receiving current Ira proportional to the brightness of the light emitting signal Lba flows through the resistor R12a. Therefore, the light reception signal d is derived from the anode of the photodiode 16a in correspondence with the light emission signal Lba. However, the light reception signal d has an inverted waveform of the light emission signal Lba.

The received light signal d is amplified by the amplifier circuit 17a,
It is input to the demodulation circuit 18a realized by a narrow band filter or the like, and the demodulation signal e is output. The demodulation signal e is inverted by the transistor Q13a at the next stage, and the emission signal Lba, that is, the reception signal f having the same phase as the transmission signal of the transceiver 12b is derived at the collector. The reception signal f is input to the signal processing means (not shown) and also to the reception confirmation circuit 22a.

The reception confirmation circuit 22a is realized by a comparison circuit or the like, compares the level of the reception signal f with a predetermined constant level, and outputs the confirmation signal g when the level of the reception signal f exceeds the predetermined level. It

As will be described later, the timer 21a receives a reception state determination signal (hereinafter referred to as a reception state determination signal) which is a response from the other party within a fixed time after the reception state confirmation signal is transmitted in the reception state confirmation operation performed prior to communication. If the "response signal") is not received, the timing signal h is set to the luminous intensity selection circuit 20.
It is output to a. The light intensity selection circuit 20a sequentially switches the selection signals D1 to D4 each time the timing signal h is input and inputs the selection signals D1 to D4 to the light intensity setting circuit 19a. The light intensity setting circuit 19a increases the current Isa flowing through the light emitting diode 15a according to the selection signals D1 to D4 and sequentially increases the light intensity of the light emission signal Lab.

FIG. 2 is a circuit diagram showing the configuration of the light intensity setting circuit 19a of this embodiment. 2, parts corresponding to those in FIG. 1 are designated by the same reference numerals. Referring also to FIG. 1, the light intensity setting circuit 19a includes switching transistors Tr1 to Tr4 that are individually turned on / off by selection signals D1 to D4, and switching transistor Tr1.
To Tr4 and resistors Rs1 to Rs4 connected in series
It consists of and. Switching transistors Tr1 to Tr4
Turns off when the selection signals D1 to D4 are at a high level "H" and turns on at a low level "L".

Switching transistors Tr1 to Tr4
Are turned on individually, the resistors Rs1 to Rs4 are turned on.
Is selected. The resistance values of the resistors Rs1, Rs2, Rs3 and Rs4 are 8: 4: 2: 1 (Rs1 = 2Rs2 in this order).
= 4Rs3 = 8Rs4). As the resistors Rs1 to Rs4 are sequentially selected by the selection signals D1 to D4, the current Is flowing through the light emitting diode 15a.
a increases like 1-2-4-8 times.

Since the luminous intensity of the light emitting diode 15a, and hence the luminous intensity of the light emitting signal Lab, is proportional to the current Isa flowing through the light emitting diode 15a, the setting of the resistance value as described above conforms to the law of inverse square of light, and the long distance It is possible to give a sufficient illuminance to the light receiving element of, while providing an appropriate illuminance to the light receiving element of a short distance.

In this embodiment, the luminous intensity of the light emitting diode 15a can be set in four steps, but the number of steps is not limited to four.

FIG. 3 is a circuit diagram showing the structure of a light intensity setting circuit 29a according to another embodiment of the present invention. 3, parts corresponding to those in FIG. 2 are designated by the same reference numerals. The light intensity setting circuit 29a has a transistor Q1 at one end.
Resistances Rb1 to Rb4 commonly connected to the base of 2a
And analog switches As1 to As4 individually connected to the resistors Rb1 to Rb4. The other ends of the analog switches As1 to As4 are commonly connected and the carrier signal c is input. Analog switch As1-As
4 is individually turned on / off by selection signals D1 to D4.
Turned off. As a result, for example, when the selection signal D1 is at a low level, the first analog switch As1 becomes conductive, and the carrier signal c is transferred to the transistor Q1 via the resistor Rb1.
It is connected to the base of 2a. Also, for example, the selection signal D
4 turns on the analog switch As4, the carrier signal c is transmitted through the resistor Rb4 to the transistor Q12a.
Applied to the base of. The resistance values of the resistors Rb1 to Rb4 are set to be 1: 2: 4: 8. Therefore, the ratio of the current values of the base current Ib1 when the resistance Rb1 having the highest resistance value is connected and the base current Ib4 when the resistance Rb4 having the lowest resistance value is connected is 1: 8. Similarly, the base current Ib2 when the resistor Rb2 is selected is twice the base current Ib1 and the base current Ib when the resistor Rb3 is selected.
The current value of b3 becomes four times. That is, each resistance R
By selecting b1 to Rb4, the base current changes by 1-2-4-8 times. In general, the collector current of the transistor is determined by the product of the base current and the current amplification factor hfe, so that the current amplification factor h of the transistor Q12a is
When fe is constant, the current Isa flowing through the light emitting diode 15a is determined by the magnitude of the base current. In this embodiment, the value of the current Isa flowing through the light emitting diode 15a connected to the collector is changed by changing the base resistance of the transistor Q12a. That is, the base resistors Rb1 to Rb
By changing b4, the value of the current Isa is 1-2.
-4-8 times. Therefore, also in this embodiment, the luminous intensity of the light emitting diode 15a, that is, the light emission signal Lab.
It is possible to set the luminosity of 4 levels to four levels and also to a level according to the reaching distance.

In the present embodiment, as described above, the luminous intensity of the light emitting diode which is the light source is increased stepwise according to the distance to the other party, and the reception state confirmation operation is performed prior to the communication to obtain an appropriate luminous intensity. Is set.

FIG. 4 is a flow chart showing the receiving state confirmation operation of the transmitter / receiver 12a on the transmitting side. Description will be made with reference to FIGS. In performing the reception state confirmation operation, it is assumed that the pair of transceivers 12a and 12b are set to be capable of transmitting and receiving each other.
In addition, the light emitting diodes 15a of the transceivers 12a and 12b,
The luminosity of 15b is set in four steps from the minimum luminosity 1 to the maximum luminosity 4.

In step S1, the transmitter / receiver (hereinafter, also referred to as "transmission side") 12a starts a reception state confirmation operation. In step S2, the luminous intensity n of the light emitting diode 15a is 1
The switching transistor Tr1 corresponding to the first stage of the minimum luminous intensity, which is set to the stage, is turned on in step S3, the light emitting diode 15a emits light with luminous intensity 1, and in step S4, the reception state confirmation signal is a specific code (for example, " 5
5H ”) four times to the transmitter / receiver (hereinafter also referred to as“ reception side ”) 12b. Simultaneously with the end of transmission, the timer 21a is set to the fixed time Ta.

In the present invention, the transmitting side 12a to the receiving side 12a
When the reception state confirmation signal is sent to b, it is transmitted at the number of times obtained by subtracting the set number of luminous intensity stages from the number obtained by adding 1 to the number of luminous intensity set stages (4 in this embodiment). Has become. For example, when transmitting with a luminous intensity of 1, (4 + 1) -1
= 4 times, (4 + 1) −2 = 3 times at the light intensity of 2, 2 times at the light intensity of 3, and once at the light intensity of 4 at the maximum light intensity. The receiving side 12b sends a response signal to the transmitting side 12a the same number of times as the receiving state confirmation signal is received, and the luminous intensity of the receiving side 12a at this time is 1 when the number of times of reception is increased. Is set. The response signal sent from the receiving side uses the same code as the receiving state confirmation signal (for example, "55H"). If the receiving state confirmation signal is received twice, the response signal of luminous intensity 3 is transmitted twice. 12a, and the sending side 12a can know the receiving state of the other party. In this way, the number of transmissions is such that the luminous intensity information is sent at the same time. Therefore, for example, if four responses are obtained for four transmissions, it is determined that the reception status confirmation signal is received without error, and two responses are sent. If this is the case, it is determined that the reception status is poor due to insufficient light intensity or a reading error due to noise.

In step S5, it is determined whether the response signal from the receiving side 12b is received within the set time of the timer 21a. The same specific code (for example, "55H") as the reception state confirmation signal is used for the response signal. When the response signal is received, the process proceeds to step S6, and the number of times m the response signal is received is checked. If the same number of response signals as the number of times the reception status confirmation signal is transmitted are obtained, it is determined that the signal has been received without error, and step S7 is performed.
Proceed to. In step S7, the transmission side 12a sends a response confirmation signal to the reception side 12b to inform it that communication is to be started. The response confirmation signal is, for example, “AAH” (101010).
Although different from the reception status confirmation signal as in 10), a code having regularity in the array of 1,0 is used.

In step S8, the transmission side 12a receives the reception OK signal from the reception side 12b in response to the response confirmation signal. As a result, after step S9, the communication state is established and optical communication is performed. At step S10, the optical communication ends and the end is reached.

Returning to step S5, if the response signal from the receiving side 12b is not received, the process proceeds to step S11,
If the set time Ta of the timer 21a has elapsed, step S1
Go to 2. Further, in step S6, the number m of times the response signal is received
Also does not match the number of transmissions of the reception state confirmation signal, the process proceeds to step S12.

In step S12, the switching transistor Tr1 which has been turned on is turned off, the switching transistor Tr2 is turned on instead, and the light emitting diode 1 is turned on.
The luminous intensity of 5a is increased by one step, and the process proceeds to step S14, where it is determined whether or not the newly set luminous intensity stage exceeds the preset number of stages (4 in this embodiment). If it does not exceed, the process returns to step S3, the switching transistor Tr2 corresponding to the light intensity one step higher is turned on, and the reception state confirmation signal with the light intensity 2 newly set in step S4 is transmitted three times, which is one less than the previous time. . The same operation is repeated thereafter, and the number of transmissions is reduced by one each time the luminous intensity is increased by one step. Further, if the luminous intensity level set in step S14 exceeds the predetermined number of levels, it is determined that no response is obtained even though the luminous intensity is transmitted at all levels, and it is determined as an error in step S15. After the error processing is executed, the subsequent transmission is aborted.

FIG. 5 is a flow chart showing the receiving state confirmation operation of the transceiver 12b on the receiving side. In step R1, the transceiver 12b enters the reception confirmation operation, and in step R2, it is determined whether or not the reception state confirmation signal from the transmission side 12a is received. If received, step R
3, the luminous intensity (n = p) of the number of steps equal to the number p of times the reception state confirmation signal is received is set, and the step R
At 4 the corresponding switching transistor Tr (n) is turned on. For example, if the reception state confirmation signal is received three times, the luminous intensity is set to 3. After setting the luminosity, the process proceeds to step R5.

In step R5, the response signal having the luminous intensity n is sent to the transmitting side 12a p times. The same code (for example, "55H") as the reception state confirmation signal is used for the response signal.
When the transmission of the response signal is completed, the timer 21b sets the fixed time Tb.
And the switching transistor Tr (n) is turned off in step R6, and step R7
Then, the signal sent from the sending side 12a is judged after sending the response signal. The operation of the transmission side 12a in response to the response signal from the reception side 12b is as described in step S5 and subsequent steps in FIG. The transmission side 12a transmits the response confirmation signal or the reception state confirmation signal to the reception side 12b based on the number of times the response signal is received, as described above.

At step R7, it is judged whether or not the signal is a reception side state confirmation signal. If it is a reception state confirmation signal, the process returns to step R3, the light intensity is set based on the number of receptions, and the same operation as the previous time is repeated. If it is not the reception state confirmation signal, the process proceeds to step R8 and it is determined whether it is a response confirmation signal. If it is a response confirmation signal, the process proceeds to step R9 and the reception OK signal is sent to the transmission side 12a. OK to receive
The signal is the same specific code as the response confirmation signal (for example, "AA").
H ”) is used and is a signal that requests the transmission side 12a to start communication. The transmitting side 12a starts the optical communication when receiving the reception OK signal, performs the optical communication at Step R10, and becomes the end after the optical communication ends at Step R11.

When the response confirmation signal is not received at step R8, the routine proceeds to step R12, where it is determined whether the response confirmation signal is received within the fixed time Tb set by the timer 21b. Tb not received
When is passed, the process proceeds to step R13, it is determined that an error has occurred, and the process ends.

In the above-mentioned embodiments, the light intensity of the light emitting diode is set in four steps so that the light thickness is sequentially stepped up depending on the presence or absence of a response from the other party. However, the light intensity setting circuit 19a or 29a is externally connected. The setting signal may be input from. This makes it possible to manually raise the luminous intensity, and it is possible to deal with a case where it is determined that communication is uncertain with the automatically set luminous intensity.

In this embodiment, the reception state confirming operation is performed prior to the optical communication in this way to always obtain an appropriate luminous intensity corresponding to the distance to the other party. Excessive and useless power consumption is not forced, and problems such as signal misidentification due to saturation of the light receiving element do not occur even at a short distance.

[0054]

As described above, according to the present invention, the reception state confirmation signal is sequentially sent from the optical transmitter to the optical receiver at a plurality of stages of light intensity prior to the communication, and the optical receiver receives the signal. When the reception status confirmation signal is received, the reception status determination signal is sent to respond, so the luminous intensity corresponding to the distance with the other party is set, and the reliable communication status is guaranteed and the distance Since the luminosity is set correspondingly, the waste of power consumption due to the luminosity beyond the required stage is eliminated.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an optical communication device 11 which is an embodiment of the present invention.

FIG. 2 is a light intensity setting circuit 19a used in the communication device 11.
3 is a circuit diagram showing the configuration of FIG.

FIG. 3 is a light intensity setting circuit 29a used in the communication device 11.
3 is a circuit diagram showing the configuration of FIG.

FIG. 4 is a flowchart illustrating a reception state confirmation operation of the transceiver 12a that is an embodiment of the present invention.

FIG. 5 is a flowchart showing a reception state confirmation operation of the transceiver 12b which is an embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of an optical communication device 1 according to a conventional technique.

FIG. 7 is a waveform diagram showing signal waveforms used in optical communication.

FIG. 8 is a circuit diagram showing a part of a configuration of a transmitter 3a and a receiver 6b of the optical communication device 1.

FIG. 9 is a diagram for explaining the relationship between the distance between the transmitter and the receiver and the luminous intensity in the optical communication device.

[Explanation of symbols]

 11 Optical communication device 12a, 12b Transceiver 13a, 13b Transmitting circuit 14a, 14b Receiving circuit 15a, 15b Light emitting diode 16a, 16b Photodiode 19a Luminous intensity setting circuit 20a, 20b Luminous intensity selecting circuit 21a, 21b Timer 22a, 22b Reception confirmation circuit 23a, 23b Signal generation circuit 24a, 24b Oscillation circuit 29a Luminous intensity setting circuit a Transmission signal b Carrier wave c Carrier signal D1-D4 Luminous intensity selection signal g Confirmation signal Lab, Lba Light emission signal

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H04B 10/04

Claims (3)

[Claims] 1. An optical transmitter that converts an electrical signal into an optical signal and transmits the optical signal to a receiver to perform optical communication, and a light intensity setting unit that sets the light intensity of the optical signal to be transmitted in a plurality of stages, and communication. Confirmation signal generation means for generating a predetermined reception state confirmation signal to be transmitted to the receiving device side in advance, and a predetermined reception state determination signal transmitted from the reception device side, and based on the reception state determination signal And an intensity control unit for instructing the intensity setting unit to perform an intensity setting step. 2. An optical receiving device for receiving an optical signal sent from the transmitting device side and converting it into an electric signal, receiving a predetermined reception state confirmation signal sent from the transmitting device prior to communication, An optical receiving device comprising: a reception state determination unit that determines its own reception state; and a determination signal generation unit that generates a reception state determination signal based on the determination result of the reception state determination unit. 3. An optical transmitter comprising: an optical transmitting device for converting an electric signal into an optical signal and transmitting the optical signal to a receiving device side; and an optical receiving device for receiving an optical signal sent from the optical transmitting device and converting it into an electric signal. In the communication device, the optical transmission device is a light intensity setting means for setting the light intensity of the optical signal to be transmitted in a plurality of stages, and a confirmation for generating a predetermined reception state confirmation signal to be transmitted to the reception device side prior to communication. And a light intensity control unit that receives a predetermined reception state determination signal sent from the receiving device side and instructs the light intensity setting unit to perform a light intensity setting step based on the reception state determination signal. The optical receiving device receives a predetermined receiving state confirmation signal sent from the transmitting device prior to communication, and determines a receiving state of itself, and a receiving state determining means, Based on the stage of the determination result, the optical communication device characterized by including a discrimination signal generating means for generating a discrimination signal.