JP3086580B2 - Optical communication device - 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 having a bidirectional communication function.

[0002]

2. Description of the Related Art Optical communication devices are mutually light emitting elements (light sources).
And a light-receiving element, transmit light to the other party, receive light from the other party, and perform communication.It can transmit and receive wirelessly, it is not affected by electromagnetic disturbance, modulation on the transmitting side and There is an advantage that demodulation on the receiving side can be realized with a simple circuit configuration.

FIG. 6 is a block diagram showing an 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 the sake of convenience of description, the two have the same configuration, and the blocks arranged symmetrically are distinguished by adding a and b to the reference numerals. One transceiver 2a includes a transmitting unit 3a and a receiving unit 4a. The transmission unit 2a drives the light emitting element 4a as a light source, and sends out an optical signal Lab to a transceiver 2b as a partner. As 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). The transmitted optical signal L
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 b, for example, a photodiode is used. Less than,
The light receiving element 5b (5a) may be referred to as a photodiode 5b (5a).

[0004] The optical signal Lba from the transceiver 2b to the transceiver 2a is transmitted and received in the same procedure, and bidirectional communication is performed.

FIG. 7 is a waveform diagram showing signal waveforms used for optical communication. In optical communication, binary signals of “1” and “0” are used, and “1” is represented when the light emitting element is turned on (ON) and “0” is displayed when the light emitting element is turned off (OFF). FIG. 7A shows the waveform of a transmission signal a of 1, 0, 1, 0,... Transmitted to the other party.

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

By inputting the transmission signal a and the carrier b to, for example, an AND gate Q1 shown in FIG. 7 (4), a carrier signal c having a waveform shown in FIG. 8 (3) is output from the AND gate Q1. Is output. The reason why such a high-frequency modulated carrier signal c is used for optical communication is 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. 8, parts corresponding to those in FIG. 6 are denoted by the same reference numerals. The anode of the light emitting diode 4a has a protection resistor R2
The power supply voltage Vca is applied via a. The cathode of the light emitting diode 4a is grounded via a transistor Q2a provided in the transmitting section 3a. Therefore, when the transistor Q2a is turned on, the light emission current Isa
Flows, and the light emitting diode 4a emits light.

In the transmitting 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
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 at the cycle of the carrier wave b. As a result, the high-frequency modulated light-emitting signal Lab is transmitted from the transmitting unit 3a and enters the photodiode 5b provided in the other receiving unit 6b.

The conductivity of the photodiode 5b changes according to the light emission signal Lab, and a light receiving current Irb proportional to the brightness of incident light flows in the direction shown in the figure via the resistor R3b. Therefore, a light receiving signal d obtained by inverting the light emitting signal Lab is derived to the anode of the photodiode 5b. The light receiving 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 demodulated signal e is output. The demodulated signal e is inverted by an inverting circuit realized by a transistor Q3d and a collector resistor R4b, and a received signal a synchronized with the transmission signal a is derived from the collector. In this way, the 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]

SUMMARY OF THE INVENTION Wireless optical communication
The advantage is that no transmission means such as a cable is required, but the light emitted into the space is diffused, so that the reach is limited. Also the brightness (illuminance) of the light at the light receiving location
Is proportional to the brightness (luminous intensity) of the light source and inversely proportional to the distance according to the inverse square law, so that, for example, as shown in FIG. The illuminance is 4: 1 between the light receiving position c and the double distance 2a.
That is, the luminous intensity for the light receiving position b may be one fourth of the luminous intensity for 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-described optical communication device according to the related art, a 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 at a constant luminous intensity. Therefore, assuming that the set distance is the distance 2a shown in FIG. 9A, three-quarters of the power is wasted when transmitting to the light receiving position b at a half distance. That was the problem. On the other hand, when transmitting to a double distance, four times as much power is required. In the case of a portable device used outdoors, there is a problem that the battery capacity increases and the size and weight of the device are reduced.

Further, as shown in FIG.
When the two light receiving positions a and b are at the close distance Δa, the amount of light received at the light receiving position d becomes excessive under the aforementioned constant luminous intensity, the light receiving elements such as the photodiodes are saturated, and the light source is turned off. However, since current flows through the light receiving element for a while, there is a problem that the light receiving element is erroneously recognized as being in the receiving state.

[0014] These problems arise from the fact that the luminous intensity is set to be constant in anticipation of the maximum reach of the optical communication device.

Accordingly, an object of the present invention is to provide an optical communication device which solves the above-mentioned problems, changes the light emission intensity in accordance with the distance to the other party, and realizes a good communication state.

[0016]

According to the present invention, (a) the light-emitting element 15a, (b) the light-receiving element 16a, and (c) within a predetermined time Ta after transmission of the reception state confirmation signal by the light-emitting element 15a. When the response signal g of the number m corresponding to the transmitted reception state confirmation signal is not given,
A timer 21a that outputs a timing signal h; and (d) the luminous intensity of the light emitting element 15a of the optical signal transmitted prior to the optical communication in response to the timing signal h is set to the minimum luminous intensity among the luminous intensity of a plurality of predetermined stages. , Each time a timing signal h given thereafter is received,
5a, the luminous intensity according to 5a is increased stepwise from the minimum luminous intensity,
And, as the luminous intensity increases, the light emitting element 15a is driven at the smaller number m corresponding to the luminous intensity, the reception state confirmation signal is transmitted within the predetermined time Ta, and the light emitting element 15a after driving is driven. If the timing signal h is not given within the predetermined time Ta, the timing signal h
And (e) responding to the output of the light receiving element 16a and receiving a reception state confirmation signal exceeding a predetermined level in response to the output of the light receiving element 16a. Receiving confirmation means 22 for generating signal g and providing it to timer 21a
a. An optical transmitter comprising: a.

Further, according to the present invention, (a) the light emitting element 15b, (b) the second light receiving element 16b, and (c) a predetermined time T after the response signal g is given.
(d) a number p corresponding to the number of times the response signal g has been received is set within the predetermined time Tb set by the timer 21, and the set number p is large. Light emitting element 1
5b, the light intensity is increased stepwise from the minimum light intensity, and the light emitting element 15b is driven at the light intensity corresponding to the set number p at the set number p and transmitted as the reception confirmation signal within the predetermined time Tb. Setting means 19b, 20b
(E) when a reception state confirmation signal exceeding a predetermined level is received in response to the output of the light receiving element 16b, a reception confirmation means 22 which generates a response signal g and gives it to the timer 21b
b.

According to the present invention, in an optical communication device in which an optical transmitting device and an optical receiving device perform optical communication with each other, the optical transmitting device 12a comprises: (a) a first light emitting element 15a; (C) when the number m of first response signals g corresponding to the transmitted reception state confirmation signal is not provided within a predetermined time Ta after the transmission of the reception state confirmation signal by the first light emitting element 15a; A timer 21a for outputting a timing signal h; (d) responding to the timing signal h, determining the luminous intensity of the first light emitting element 15a of the optical signal to be transmitted prior to the optical communication out of a plurality of predetermined luminous intensity levels Each time the timing signal h given thereafter is received, the luminous intensity of the first light emitting element 15a is increased stepwise from the minimum luminous intensity, and the luminous intensity increases as the luminous intensity increases. By driving the first light emitting element 15a with the small number m, the reception state confirmation signal is transmitted within the predetermined time Ta, and the timing is controlled within the predetermined time Ta after driving the first light emitting element 15a. When the signal h is not supplied, the first luminous intensity selecting and setting means 19a and 20a for performing the transmitting operation at the luminous intensity when the timing signal h is not supplied; and (e) responding to the output of the first light receiving element 16a, A first reception confirmation unit 22a for generating a first response signal g and providing it to the timer 21a when a reception state confirmation signal exceeding a predetermined level is received; (G) a second light receiving element 16b; (h) a timer 21 for setting a predetermined time Tb after the second response signal g is given; and (i) a timer set for the timer 21. Within the determined time Tb, a number p corresponding to the number of receptions to which the response signal g is given is set. As the set number p increases, the luminous intensity of the second light emitting element 15b increases stepwise from the minimum luminous intensity, A second light intensity selection and setting means 19b, 20b for driving the two light emitting elements 15b at the set number of times p at a light intensity corresponding to the set number of times p and transmitting as a second reception confirmation signal within the predetermined time Tb; (J) When a reception state confirmation signal exceeding a predetermined level is received in response to the output of the second light receiving element 16b, a second reception confirmation unit 22b that generates a second response signal g and provides the second response signal g to the timer 21b The first predetermined time Ta of the first timer 21a is equal to the second predetermined time Tb of the second timer 21b, and corresponds to the luminous intensity of the first light emitting element 15a of the optical transmitter 12a. A number of transmission times m that is an optical communication system, characterized in that it is chosen equal to the set number p corresponding to the intensity of the second light emitting element 15b of the optical receiver 12b.

[0019]

The optical communication device according to the present invention includes an optical transmission device that performs an optical communication by converting an electric signal into an optical signal, and an optical receiving device that receives the optical signal and converts it into an electric signal.

The optical transmitter 12a transmits a reception state confirmation signal from the light emitting element 15a a predetermined number of times m with the minimum luminous intensity, gives the output of the light receiving element 16a to the reception confirmation means 22a, and receives the signal by the light receiving element 16a. When the reception state confirmation signal exceeds a predetermined level, a response signal g is generated and given to the timer 21a. The timer 21a transmits the response signal g within a predetermined time Ta after the transmission of the reception state confirmation signal by the light emitting element 15a. When the number m corresponding to the reception state confirmation signal and the response signal g cannot be obtained from the reception confirmation means 22a, the timing signal h is output, and when the timing signal h cannot be obtained from the timer 21a by repeating this operation. The luminous intensity of the light emitting element 16a at the time of transmitting the reception state confirmation signal is
Each time the response signal g is not obtained by the number m, the number is increased stepwise from the minimum luminous intensity and the number m is set small.

The optical receiving device 12b has a configuration similar to the above-described optical transmitting device, and the luminous intensity selecting and setting means 19b and 20b set the time within the time Tb set by the timer 21b.
The number p corresponding to the number of receptions to which the response signal g is given is set, and as the set number p increases, the luminous intensity of the light emitting element 15b is increased stepwise from the minimum luminous intensity. Is transmitted by driving the light emitting element 15b.

The optical communication device is configured by combining the above-described optical transmitting device and the above-described optical receiving device, and can perform mutual optical communication with the least possible power consumption of the light emitting elements 15a and 15b. become.

[0023]

FIG. 1 is a block diagram showing an electrical configuration of an optical communication apparatus according to one 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 as a transmission unit, a reception circuit 14a as a reception unit, an operation unit and a power supply circuit (not shown), and the like.

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

Light emitting diodes 15a (15b), AND
Gate Q11a (Q11b), transistor Q12a
(Q12b), luminosity setting circuit 19a (19b), luminosity selection circuit 20a (20b), timer 21a (21b), signal generation circuit 23a (23b), oscillation circuit 24a (24
b).

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

The photodiodes (light receiving elements) 16a (16
b), the amplification circuit 17a (17b), and the demodulation circuit 18a (1
8b), a transistor Q13a (Q13b), and a reception confirmation circuit 22a (22b).

The configuration 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.
, A 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 a reception state between devices in addition to a transmission signal used for optical communication. The confirmation signal includes, for example, “55H” (0101010) for easy discrimination.
A code in which 1, 0 are regularly arranged as in 1) is selected.

The transistor Q12a forms a switch circuit. The transistor Q12a is on when the carrier signal c is "1" as shown in FIG. 8, and is off when the carrier signal c is "0". The power supply voltage Vc is applied to the collector of the transistor Q12a via a series circuit of the light emitting diode 15a and the luminous intensity setting circuit 19a. When the transistor Q12a is on, 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 is a luminous intensity setting means for setting the luminous intensity of the light emitting diode 15a in a plurality of stages, and the luminous intensity control circuit instructs the luminous intensity setting circuit 19a to perform the luminous intensity setting stage. A light intensity selection circuit 20a 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 configuration of the receiving circuit 14a will be described. The photodiode 16a receives the emitted light signal L
The conductivity changes according to ba, and a light reception current Ira proportional to the brightness of the light emission signal Lba flows through the resistor R12a. Therefore, a light receiving signal d is derived from the anode of the photodiode 16a in accordance with the light emitting signal Lba. However, the light receiving signal d has an inverted waveform of the light emitting signal Lba.

After the light receiving signal d is amplified by the amplifier circuit 17a,
The signal is input to a demodulation circuit 18a realized by a narrow band filter or the like, and a demodulated signal e is output. The demodulated signal e is inverted by the transistor Q13a at the next stage, and a light-emitting signal Lba, that is, a received 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 a signal processing means (not shown) and also to a 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 a confirmation signal g when the level of the reception signal f exceeds the predetermined level. You.

As will be described later, the timer 21a transmits a reception state discrimination signal (hereinafter, referred to as a response from the other party) within a predetermined time after transmitting the reception state confirmation signal during a reception state confirmation operation performed prior to communication. When the response signal g cannot be received by the number of receptions m described below, the timing signal h is output to the light intensity selection circuit 20a. The luminosity selection circuit 20a sequentially switches the selection signals D1 to D4 every time the timing signal h is input, and sets the luminosity setting circuit 19a.
To enter. The luminosity setting circuit 19a provides the selection signal D1
To D4, the current Is flowing through the light emitting diode 15a
is increased, and the luminous intensity of the light emission signal Lab is sequentially increased.

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

Switching transistors Tr1 to Tr4
Are turned on individually, the resistances Rs1 to Rs4
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, that is, the luminous intensity of the light emitting signal Lab is proportional to the current Isa flowing through the light emitting diode 15a, the above-described setting of the resistance value conforms to the inverse square law of light, A sufficient illuminance can be given to the light receiving element of the above, and an appropriate illuminance can also be given to the light receiving element at a short distance.

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

FIG. 3 is a circuit diagram showing a configuration of a light intensity setting circuit 29a according to another embodiment of the present invention. 3, parts corresponding to those in FIG. 2 are denoted by the same reference numerals. The light intensity setting circuit 29a has one end connected to the transistor Q1.
Resistors 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 a carrier signal c is input. Analog switches As1 to As
4 are individually turned on / off by selection signals D1 to D4.
Turned off. Thus, for example, when the selection signal D1 is at a low level, the first analog switch As1 is turned on, and the carrier signal c is applied to the transistor Q1 via the resistor Rb1.
2a. Further, for example, selection signal D
4, when the analog switch As4 is turned on, the carrier signal c is applied to the transistor Q12a via the resistor Rb4.
Applied to the base. The resistance values of the resistors Rb1 to Rb4 are set at 1: 2: 4: 8. Accordingly, the ratio of the base current Ib1 when the resistor Rb1 having the highest resistance is connected to the base current Ib4 when the resistor Rb4 having the lowest resistance 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 is quadrupled. That is, each resistance R
By selecting b1 to Rb4, the base current changes like 1-2-4-8 times. Generally, the collector current of the transistor is determined by the product of the base current and the current amplification factor hfe.
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 Rb1
By changing b4, the value of the current Isa becomes 1-2.
−4 to 8 times. Therefore, also in this embodiment, the light intensity of the light emitting diode 15a, that is, the light emission signal Lab
Can be set to four levels and to a level corresponding to the reach distance.

In this 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 checking operation is performed prior to communication to obtain an appropriate luminous intensity. Is set.

FIG. 4 is a flowchart showing the receiving state confirmation operation of the transceiver 12a on the transmitting side. This will be described with reference to FIGS. In performing the reception state checking operation, it is assumed that the pair of transceivers 12a and 12b are set in a state where transmission and reception can be performed with each other.
The light emitting diodes 15a of the transceivers 12a and 12b,
It is assumed that the luminous intensity of 15b is set in four steps from a minimum luminous intensity of 1 to a maximum luminous intensity of 4.

In step S1, the transceiver (hereinafter, also referred to as "transmission side") 12a enters a reception state confirmation operation. In step S2, the light intensity n of the light emitting diode 15a is 1
The switching transistor Tr1 corresponding to the first stage of the minimum luminous intensity is turned on in step S3, the light emitting diode 15a emits light at luminous intensity 1, and the reception state confirmation signal is a specific code (for example, " 5
5H ") four times to the transceiver (hereinafter, also referred to as" receiving side ") 12b. At the same time as the end of the transmission, the timer 21a is set to the predetermined time Ta.

According to the present invention, the transmitting side 12a is connected to the receiving side 12a.
When the reception state confirmation signal is sent to b, the number of luminous intensity setting steps (4 in the present embodiment) is added to 1, and the number of luminous intensity steps is subtracted from the set number, so that the number of luminous intensity setting steps is subtracted. Has become. For example, when transmitting at luminous intensity 1, (4 + 1) -1
= 4 times, (4 + 1)-2 = 3 times at luminous intensity 2, and so on at luminous intensity 3 twice, and once at luminous intensity 4 at maximum luminous intensity. The receiving side 12b sends a response signal to the transmitting side 12a as many times as the number of times the receiving state confirmation signal is received, and the luminous intensity of the receiving side 12a at this stage is obtained by adding 1 to the number of times of receiving. Is set. The response signal transmitted from the receiving side uses the same code (for example, “55H”) as the reception state confirmation signal, and if the reception state confirmation signal is received twice, the response signal of luminous intensity 3 is transmitted twice. The transmission side 12a can know the reception state of the other party. As described above, the number of transmissions is to transmit light intensity information at the same time. Therefore, for example, if four responses are obtained for four transmissions, it is determined that the reception state confirmation signal has been received without error, and two responses are received. If so, it is determined that the reception state is poor due to insufficient light intensity or reading error due to noise.

In step S5, it is determined whether a response signal has been received from the receiving side 12b within the time set by the timer 21a. The same specific code (for example, “55H”) as the reception state confirmation signal is used for the response signal. If the response signal has been received, the process proceeds to step S6, where the number m of response signal receptions is checked. If a response signal having the same number of times as the number of transmissions of the reception state confirmation signal is obtained, it is determined that the signal has been received without error, and step S7 is performed.
Proceed to. In step S7, the transmitting side 12a transmits a response confirmation signal to the receiving side 12b to inform that the 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 regular code is used in the arrangement of 1,0.

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

Returning to step S5, if no response signal is received from the receiving side 12b, the process proceeds to step S11,
If the set time Ta of the timer 21a elapses, step S1 is executed.
Proceed to 2. Also, in step S6, the number of receptions of the response signal m
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, and the switching transistor Tr2 is turned on instead.
The luminous intensity of 5a is raised by one step, and the process proceeds to step S14, where it is determined whether the newly set luminous intensity level exceeds a preset number of levels (four in this embodiment). If not, the process returns to step S3, and the switching transistor Tr2 corresponding to the luminous intensity one step higher is turned on. In step S4, the reception state confirmation signal based on the newly set luminous intensity 2 is transmitted three times, one less than the previous time. . Thereafter, the same operation is repeated, and the number of transmissions is reduced by one each time the luminous intensity is raised by one step. If the luminous intensity level set in step S14 exceeds a predetermined number of stages, it is determined that an error has occurred in step S15 because no response was obtained despite transmission at all luminous intensity levels, After performing the error processing, the subsequent transmission is terminated.

FIG. 5 is a flowchart showing the receiving state checking operation of the transceiver 12b on the receiving side. In step R1, the transceiver 12b enters a reception confirmation operation, and in step R2, it is determined whether or not a reception state confirmation signal has been received from the transmission side 12a. Step R if received
3, the number of steps (n = p) equal to the number p of times the reception state confirmation signal has been received is set, and 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, a response signal having a 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 ends, the timer 21 b
At the same time, the switching transistor Tr (n) is turned off at step R6, and at step R7
After transmitting the response signal, the signal transmitted from the transmitting side 12a is determined. The operation of the transmitting side 12a in response to the response signal from the receiving side 12b is the same as that 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 has been received, as described above.

In step R7, it is determined whether or not the received signal is a state confirmation signal on the receiving side. If the signal is a reception state confirmation signal, the process returns to step R3, where the luminosity is set based on the number of receptions, and the same operation as the previous time is repeated. If the signal is not a reception state confirmation signal, the process proceeds to step R8, where it is determined whether the signal is a response confirmation signal. If it is a response confirmation signal, the process proceeds to step R9, where a reception OK signal is sent to the transmission side 12a. Receive OK
The signal is the same specific code as the response confirmation signal (for example, "AA
H ") is a signal for requesting the transmission side 12a to start communication. The transmitting side 12a starts optical communication when receiving the reception OK signal, performs optical communication in step R10, and ends after completing optical communication in step R11.

If no response confirmation signal is received in step R8, the process proceeds to step R12, and it is determined whether or not a response confirmation signal is received within a predetermined time Tb set by the timer 21b. A certain time Tb without receiving
Has elapsed, the process proceeds to step R13, where it is determined that an error has occurred, and the process ends.

In the above-described embodiments, the light intensity of the light emitting diode is set to four levels, and the light thickness is sequentially stepped up depending on the presence or absence of a response from the other party. The setting signal may be input from the device. As a result, the luminous intensity can be increased manually or the like, and it is possible to cope with a case where it is determined that communication is uneasy with the automatically set luminous intensity.

In the present embodiment, the reception state checking operation is performed prior to the optical communication in this manner, and an appropriate luminous intensity corresponding to the distance to the other party is always obtained. No excessive and unnecessary power consumption is imposed, and no problem such as erroneous signal recognition due to saturation of the light receiving element occurs even at a short distance.

[0054]

As described above, according to the present invention, prior to communication, a reception state confirmation signal is sequentially transmitted from the optical transmitting device to the optical receiving device at a plurality of levels of luminous intensity. When the reception status confirmation signal is received, the reception status discrimination signal is sent and responded, so the luminous intensity corresponding to the distance to the other party is set, and a reliable communication state is guaranteed, and Since the luminous intensity is set correspondingly, waste of power consumption due to the luminous intensity exceeding the necessary stage is eliminated. In particular, according to the present invention, the light emitting element 15a of the optical transmission device
In addition, the power consumption of any of the light emitting elements 15b of the optical receiver can be reduced. Such a configuration also
Relatively simple.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an optical communication device 11 according to an embodiment of the present invention.

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

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

FIG. 5 is a flowchart showing a reception state confirmation operation of the transceiver 12b according to one embodiment of the present invention.

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

FIG. 7 is a waveform chart showing signal waveforms used for optical communication.

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

FIG. 9 is a diagram illustrating a relationship between a distance between a transceiver and a luminous intensity in the optical communication device.

[Explanation of symbols]

 Reference Signs List 11 optical communication device 12a, 12b transceiver 13a, 13b transmitting circuit 14a, 14b receiving circuit 15a, 15b light emitting diode 16a, 16b photodiode 19a light intensity setting circuit 20a, 20b light intensity selection circuit 21a, 21b timer 22a, 22b reception confirmation circuit 23a, 23b Signal generation circuit 24a, 24b Oscillation circuit 29a Light intensity setting circuit a Transmission signal b Carrier c Carrier signal D1 to D4 Light intensity selection signal g Confirmation signal Lab, Lba Light emission signal

Claims (3)

(57) [Claims] (A) a light emitting element 15a; (b) a light receiving element 16a; and (c) a transmission state confirmation signal transmitted within a predetermined time Ta after transmission of the reception state confirmation signal by the light emitting element 15a. When the corresponding number m of response signals g is not given,
(D) responding to the timing signal h, setting the light intensity of the light emitting element 15a of the optical signal to be transmitted prior to the optical communication to the minimum light intensity among a plurality of predetermined light intensity levels; Each time a timing signal h given thereafter is received, the luminous intensity of the light emitting element 15a is increased stepwise from the minimum luminous intensity, and as the luminous intensity increases, the light is emitted at the smaller number m corresponding to the luminous intensity. When the element 15a is driven, the reception state confirmation signal is transmitted within the predetermined time Ta, and when the timing signal h is not provided within the predetermined time Ta after driving the light emitting element 15a, the timing signal is transmitted. (e) responding to the output of the light receiving element 16a, the light intensity selecting and setting means 19a, 20a for performing the transmitting operation at the light intensity when h is not given; When the reception state confirmation signal exceeding the level is received, acknowledgment means giving to the timer 21a generates a response signal g 22
a. an optical transmission device comprising: (A) a light emitting element 15b; (b) a second light receiving element 16b; and (c) a predetermined time T after the response signal g is given.
b) a timer 21 for setting b, and (d) a number p corresponding to the number of receptions given the response signal g within the predetermined time Tb set by the timer 21; The light intensity of the light emitting element 15b is gradually increased from the minimum light intensity, and the light emitting element 15b is set at the set number p by the set number p.
Luminous intensity selection setting means 19b, which is driven at a luminous intensity corresponding to, and transmits as a reception confirmation signal within the predetermined time Tb,
(E) when a reception state confirmation signal exceeding a predetermined level is received in response to the output of the light receiving element 16b, generates a response signal g and gives it to the timer 21b.
b. 3. An optical communication device in which an optical transmitting device and an optical receiving device perform optical communication with each other, wherein the optical transmitting device 12a comprises: (a) a first light emitting element 15a; and (b) a first light receiving element 16a. (C) when the number m of first response signals g corresponding to the transmitted reception state confirmation signal is not provided within a predetermined time Ta after the transmission of the reception state confirmation signal by the first light emitting element 15a, (d) a first light emitting element 15a of an optical signal to be transmitted prior to optical communication in response to the timing signal h.
Is the minimum luminous intensity among a plurality of predetermined luminous intensity, and every time the timing signal h given thereafter is received, the luminous intensity by the first light emitting element 15a is increased stepwise from the minimum luminous intensity, In addition, as the luminous intensity increases, the first light emitting element 15a is driven at the smaller number m corresponding to the luminous intensity, and the reception state confirmation signal is transmitted within the predetermined time Ta. The predetermined time Ta after driving
When the timing signal h is not supplied, the first luminous intensity selecting and setting means 19a and 20a for performing the transmission operation at the luminous intensity when the timing signal h is not supplied, and (e) the output of the first light receiving element 16a And a first reception confirmation unit 22a that generates a first response signal g and provides the first response signal g to the timer 21a when a reception state confirmation signal exceeding a predetermined level is received. (2) a second light emitting element 15b, (g) a second light receiving element 16b, (h) a timer 21 for setting a predetermined time Tb after the second response signal g is given, and (i) setting of the timer 21. The number p corresponding to the number of receptions to which the response signal g is given is set within the predetermined time Tb, and as the set number p increases, the luminous intensity of the second light emitting element 15b is increased stepwise from the minimum luminous intensity. To The second light emitting element 15b is driven at a light intensity corresponding to the set number of times p and the predetermined time Tb.
And (j) when a reception state confirmation signal exceeding a predetermined level is received in response to the output of the second light receiving element 16b, A second reception confirmation means 22b for generating a second response signal g and providing the second response signal g to the timer 21b, the first time Ta of the first timer 21a being predetermined,
The predetermined second time Tb of the second timer 21b is equal to the number of transmissions m corresponding to the luminous intensity of the first light emitting element 15a of the optical transmitter 12a, and the second light emitting element 15 of the optical receiver 12b.
The optical communication device is selected to be equal to the set number of times p corresponding to the luminous intensity of b.