JPH10233739A - Optical communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct optical communication at a low error rate independently a location of the optical communication equipment. SOLUTION: A plurality of light receiving elements PD1-PD5 placed in different directions in the optical communication equipment 23 receive individually an external optical signal. A comparator circuit 43 discriminates a level of a luminous quantity signal from a specific light receiving element connected via a changeover circuit 42, a demodulation circuit 34 demodulates a discrimination signal denoting a discrimination result to obtain a reception data signal. Furthermore, in parallel with the operation above, an error rate of each reception data signal is calculated from the reception data signal obtained by demodulating the luminous quantity signal from all the light receiving elements respectively. A selection circuit 56 selects a light receiving element with a minimum error rate of the reception data signal among the light receiving elements PD1-PD5 as a specific light receiving element and controls a changeover circuit 42 so as to connect the specific light receiving element and the comparator circuit 43. Thus, an optical signal is received by the diversity method and the reception data signal is obtained.

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 for transmitting and receiving a predetermined data signal using light.

[0002]

2. Description of the Related Art In recent years, peripheral devices such as personal computers and printers and PDAs (Personal Digital Assemblies) have been developed.
Infrared (IR) communication using infrared is used for data communication between electronic devices including a portable terminal called an istant) that mutually transmits and receives digital data signals. For this purpose, an optical communication device including a light receiving element and a light emitting element is attached to the electronic device described above.

In the infrared communication described above, an optical communication device attached to a transmission-side electronic device increases or decreases the amount of infrared light radiated from a light-emitting element, and changes the light amount of bits 0 and 1 of a digital signal to be transmitted. Generate and emit an optical signal that represents the change. The optical communication device attached to the receiving electronic device firstly
The light signal is received by the light receiving element, photoelectrically converted, and then the change in the amount of light received by the light receiving element is level discriminated at a predetermined discrimination level, thereby reproducing the bits of the digital signal. These light-emitting elements and light-receiving elements often have optical directivity, respectively. When the light-emitting elements and light-receiving elements do not mutually exist in the allowable azimuth regions respectively defined by the respective optical directivities, as described below. In addition, accurate transmission and reception of digital signals has been difficult.

FIG. 9 shows a light receiving element 1 during the above-mentioned infrared communication.
FIG. 3 is a schematic diagram illustrating a positional relationship between the light emitting devices and light emitting elements 2 and 3. In this schematic diagram, only the light receiving element 1 and the light emitting elements 2 and 3 are shown, and the remaining components of the electronic device are omitted. The light receiving permissible azimuth region 5 of the light receiving element 1 is a region within a cone having an angle θ with the center axis as a normal 7 passing through the center of the light receiving surface 6 for receiving light in the light receiving element 1. The light emitting directions 9 and 10 of the light emitting elements 2 and 3 correspond to the light emitting surfaces 11 and
The normal direction perpendicular to 12 and the emission allowable azimuth region are regions within a cone having the radiation directions 9 and 10 as central axes. The light emitting element 2 faces the light receiving element 1 on the normal line of the light receiving element 1. The light emitting element 3 faces the light receiving element 1 side, and the normal line of the light emitting surface 12 forms an angle β with the normal line of the light receiving surface 6.
Is an angle equal to or greater than the angle θ.

When optical communication is performed between the light receiving element 1 and the light emitting element 2, the light receiving surface 6 of the light receiving element 1 and the light emitting surface 11 of the light emitting element 2 face each other. Is larger than the reference amount necessary for reproducing the data signal by the level discriminating operation. Therefore, the error rate of the digital signal reproduced by the receiving optical receiver including the light receiving element 1 is less than the minimum allowable error rate allowed in data communication. When optical communication is performed between the light receiving element 1 and the light emitting element 3 described above, since the light emitting element 3 is outside the light receiving allowable azimuth region 5 of the light receiving element 1, the light receiving amount of the light signal of the light receiving element 1 is The amount of received light may be reduced below the reference amount. At this time, it is difficult to accurately reproduce the bits of the digital signal from the change in the amount of light received by the light receiving element 1, and the error rate of the digital signal tends to be higher than the minimum allowable error rate.

In the above-described optical communication device, a receiving element 14 called an IR communication unit may be used instead of the light receiving element 1 described above. The receiving element 14 includes the same light receiving element 15 as the light receiving element 1 described above,
A comparator for reproducing a digital signal by shaping the waveform of the electric signal output from 5 is integrally formed.
Therefore, due to the optical directivity of the light receiving element 15 inside the receiving element 14, the entire receiving element 14 has the same optical directivity as the light receiving element 1 as shown in FIG. Therefore, when the receiving element 14 receives the optical signal from the light emitting element 2 and reproduces the digital signal, the error rate of the digital signal becomes lower than the minimum allowable error rate. When reproducing a digital signal, the error rate of the digital signal tends to be higher than the minimum allowable error rate.

From the above, in order to accurately reproduce a digital signal in the above-described optical communication, the light receiving element 1 and the light emitting elements 2 and 3 are mutually present in the allowable azimuth region of each of the elements 1 to 3. It is necessary to arrange. Therefore, the optical communication device including the light receiving element 1 and the optical communication device including the light emitting elements 2 and 3 are set so that, for example, the light receiving surface of the light receiving element 1 and the light emitting surface of the light emitting elements 2 and 3 face each other accurately. Must be placed in When these optical communication devices are incorporated in the electronic device described above, the arrangement of the electronic devices is determined by the arrangement of the optical communication devices. May need to be placed.

Further, when optical communication is performed between the light receiving element 1 or the receiving element 14 and the light emitting elements 2 and 3, the light receiving elements 1 and 15 have different light receiving azimuthal regions 5 other than the light emitting elements 2 and 3. When a light source is present, extraneous light from the different light source is received by the light receiving elements 1 and 15 as optical noise. In this case, when an optical signal from the light emitting element 2 is received, the received light amount of the optical signal is sufficiently large. For example, the S / N ratio between the optical signal and the optical noise is sufficiently large, and Regenerating the signal is easy. However, when the optical signal from the light emitting element 3 is received, the amount of the optical signal received from the light emitting element 3 is reduced as described above. For example, the S / N ratio between the optical signal and the optical noise is reduced. And it is difficult to accurately reproduce the digital signal.
As described above, in the optical communication between the light receiving element 1 or the receiving element 14 and the light emitting elements 2 and 3, the light receiving elements 1 and 15 and the light emitting element 2 , 3
The strength of the optical signal with respect to the optical noise changes according to the positional relationship between the optical signals.

Further, the light receiving element 1 or the receiving element 1
In the optical communication device including the light emitting element 4, the communication performance indicating the relationship between the distance from the light emitting elements 2 and 3 to the light receiving elements 1 and 15 and the availability of data communication is determined.
It changes depending on the positional relationship with the reference numeral 15. For example, in FIG.
In the case where optical communication is performed between the light receiving elements 1 and 15 and the light emitting element 3 having the positional relationship indicated by 10, when another light source is within the reception allowable azimuthal region 5 of the light receiving element 1 or the receiving element 14, Therefore, the strength of the optical signal with respect to optical noise is lower than when there is no separate light source. Therefore, at this time, if the distance between the light emitting element 3 and the optical communication device is large, communication performance sufficient for the data communication described above may not be obtained.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical communication device capable of performing good optical communication regardless of the arrangement of the optical communication device on the transmitting side and the optical communication device on the receiving side. It is to be.

[0011]

According to the present invention, there is provided an optical communication device for transmitting and receiving an optical signal representing a predetermined data signal using light, wherein a plurality of optical signals are individually received under different light receiving conditions. A light receiving means, and a selecting means for selecting a light receiving means having the best light receiving state among a plurality of light receiving means,
An optical communication device, comprising: a first demodulation unit that demodulates an output signal output from the light receiving unit selected by the selection unit and obtains the data signal. According to the present invention,
An optical communication device receives an optical signal by a so-called diversity system. When this optical communication device is used as a receiving optical communication device,
The optical communication device individually receives optical signals with a plurality of light receiving units having different receiving conditions, and selects a light receiving unit having the best light receiving state among the plurality of light receiving units by a selecting unit. Is demodulated by the first demodulation means. Thus, the best data signal can always be obtained from the first demodulation unit. Further, for example, a change in light receiving conditions caused by a positional relationship between a light receiving unit of the optical communication device on the receiving side and a light emitting unit of the optical communication device on the transmitting side that has transmitted an optical signal, and the optical communication device on the receiving side The optical signal can always be received under the best light receiving condition regardless of the change of the light receiving condition caused by the positional relationship between the light receiving means and the source of the optical noise.

Further, according to the present invention, the optical communication device demodulates each of the output signals output from each of the light receiving means to obtain a data signal corresponding to each of the light receiving means. For each data signal demodulated by the demodulation means, further includes a ratio calculation means for calculating a ratio between the total data amount of the data signal and the data amount having an error, wherein the selection means includes a The light receiving means corresponding to the data signal having the smallest ratio calculated by the ratio calculating means is selected. According to the present invention, the selecting unit of the optical communication device causes the ratio calculating unit to calculate the above-mentioned ratio called an error rate from the data signal obtained by the above-mentioned second demodulating unit. The light receiving unit that receives the optical signal with the smallest ratio is selected as the selecting unit for the best light receiving state. In general, optical signals transmitted and received between optical communication devices often do not have parameters such as electric field strength which is an index of antenna switching in a diversity radio communication device. It is difficult to recognize the receiving state of the receiving means. At this time, by using the above-described selecting means, it is possible to easily generate a parameter for selecting the light receiving means in the best light receiving state from all the light receiving means. Therefore, it is possible to easily select the receiving means in the best receiving state in the diversity type optical communication device using the optical signal.

The present invention also provides an optical communication device for transmitting and receiving an optical signal representing a predetermined data signal by the amount of light, wherein a plurality of light receiving means for individually receiving the optical signal under mutually different light receiving conditions; A plurality of level adjusting means individually corresponding to each light receiving means and adjusting a light receiving level of a signal output from the corresponding light receiving means; and a light receiving means among a plurality of light receiving means from a plurality of adjusted signals. Signal selecting means for selecting a signal adjusted by the level adjusting means corresponding to the best light receiving means, and signal demodulating means for demodulating the selected signal to obtain the data signal. It is an optical communication device. According to the invention, the optical communication device adjusts the light receiving levels of the signals output from the plurality of light receiving means by the respective level adjusting means individually corresponding to the respective light receiving means. The level adjusting means is, for example, a level discriminating means, and discriminates a signal which is output from each light receiving means and indicates the amount of light received by the light receiving means by a signal level at a predetermined discrimination level. The signal demodulating unit demodulates any one of the plurality of signals whose levels have been adjusted and selected by the signal selecting unit to obtain a data signal. Thus, by adjusting the light receiving level of the signal output from the light receiving means, the signal is shaped into a waveform. Therefore, when the light receiving level of the signal from the light receiving means having a good light receiving state is adjusted, optical noise is considered to be removed from the signal. Therefore, compared with the case where the signal output from the light receiving means is directly given as in claim 1, the signal given after the level adjustment as in this claim is less affected by optical noise in the demodulation operation of the demodulation means. And a data signal can be reliably obtained.

The present invention also provides an optical communication device for transmitting and receiving an optical signal representing a predetermined data signal by the amount of light, comprising: a plurality of light receiving means for individually receiving the optical signal under mutually different light receiving conditions; Selecting means for selecting a light receiving means having the best light receiving state among a plurality of light receiving means; level adjusting means for adjusting a light receiving level of a signal output from the light receiving means selected by the selecting means; And demodulate
A signal demodulation means for obtaining the data signal. According to the present invention, the optical communication device comprises:
Any one of the plurality of light receiving means is selected by the selecting means, and the light receiving level of the signal output from the light receiving means is adjusted by the level adjusting means, and is then provided to the signal demodulating means. This level adjusting means is shared by all the light receiving means. As a result, similarly to the third aspect, the demodulation operation of the demodulation means is less affected by optical noise, and the number of components can be reduced as compared with the optical communication apparatus of the third aspect.

[0015]

FIG. 1 is a block diagram showing an electrical configuration of an electronic device 21 including an optical communication device 23 according to a first embodiment of the present invention. The electronic device 21 includes a host device 22 and an optical communication device 23. The host device 22
For example, it is realized by a peripheral device such as a personal computer and a printer, and a portable terminal. Host device 22
Transmits / receives a data signal to / from a host device of another electronic device by optical communication via the optical communication device 23. The optical communication device 23 is, for example, an optical communication device that performs infrared communication, and transmits and receives an optical signal that represents a bit of a data signal by a change in the amount of infrared light. Host device 22 and optical communication device 23
Are housed in the same housing.

The optical communication device 23 includes a data conversion circuit 25,
It is configured to include a transmission circuit 26 and a reception circuit 27.
The data conversion circuit 25 includes a transmission circuit 26 and a reception circuit 2
7 and the host device 22 for transmitting / receiving and converting data signals. Specifically, the data conversion circuit 25
Is a register 31, a control circuit 32, a modulation circuit 33
And a demodulation circuit 34. Register 31
Stores a transmission data signal supplied from the host device 22 to the modulation circuit 33 and a reception data signal supplied from the demodulation circuit 34 to the host device 22. Control circuit 32
Controls transmission and reception of a received data signal in accordance with the behavior of the register 31, the modulation circuit 33, and the demodulation circuit 34. The modulation circuit 33 generates a transmission signal described later using the transmission data signal as a modulated signal, and supplies the transmission signal to the transmission circuit 26.
The transmission circuit 26 generates an optical signal whose light amount changes, based on the transmission signal generated by the modulation circuit 33, and transmits the signal to the outside of the optical communication device 23. The receiving circuit 27
The optical signal transmitted from the optical communication device of another electronic device,
The signal is received by a so-called diversity method, and a discrimination signal described later is generated. The demodulation circuit 34 demodulates the discrimination signal output from the reception circuit 27 to obtain a reception data signal. Since the modulation circuit 33 and the demodulation circuit 34 have common circuit components, these circuits 33 and 34 may be integrated to share a common circuit component.

The transmission circuit 26 is, specifically, a driving circuit 3
6 and a pair of light emitting elements LED1 and LED2. The light emitting element LED1 has a forward input terminal connected to the power supply line 37 to which power of the voltage level + B is constantly supplied, and a forward output terminal connected to the forward input terminal of the light emitting element LED2. The forward output terminal of the light emitting element LED2 is connected to one connection terminal of the drive circuit 36. The other connection terminal of the drive circuit 36
Is connected to the modulation circuit 33 as a signal input terminal. The drive circuit 36 is a so-called buffer circuit, and includes a transistor T1 interposed between a forward output terminal of the light emitting element LED2 and a ground line.

The receiving circuit 27 specifically includes a plurality of light receiving elements, a switching circuit 42, a comparing circuit 43, and a switching control circuit 44. The plurality of light receiving elements are realized by, for example, photodiodes, and include five light receiving elements PD1 to PD5 in the following description. Each of the light receiving elements PD1 to PD5 has an optical directivity, and a light emitting element of an optical communication device of another electronic device exists in a reception allowable azimuth region defined by the optical directivity, and the light emitting element When the light-emitting surface of the light-receiving element and the light-receiving surface of the light-receiving element face each other, the best light-receiving state is obtained.

Further, all the light receiving elements PD1 to PD5 are arranged in parallel on a virtual axis along a predetermined X direction parallel to the light receiving surface, and the light receiving surfaces of the respective light receiving elements PD1 to PD5 are different from each other. It is arranged to face the direction. For example, as shown in FIG. 2, the normal lines 47 and 48 of the light receiving surfaces 45 and 46 of the light receiving elements PD1 and PD2 intersect at the mounting angle α when viewed from the X direction, as shown in FIG. Placed in The light-receiving permissible azimuth regions 49 and 50 of each of the light-receiving elements PD1 and PD2 correspond to the normal 4
This is a region within a cone having an angle θ with 7, 48 as the central axis. The aforementioned mounting angle α is selected to be less than twice the angle θ. The other light receiving elements PD3 to PD5 and the light receiving element PD2
The arrangement relationship with the light receiving elements PD1, PD2
Is equal to the arrangement relation.

2θ> α (1) As a result, the light receiving elements PD1 to PD5 are arranged so as to be sequentially shifted by the mounting angle α around the imaginary axis along the X direction. Each light receiving element PD1 to PD
5 is, for example, 45 degrees, and the mounting angle α at this time is selected to be, for example, 80 degrees. by this,
The light receiving permissible azimuth regions of the light receiving elements PD1 to PD5 overlap by 10 degrees in the YZ plane and include the entire YZ plane. It is preferable that these light receiving elements PD1 to PD5 are attached to, for example, a place in the electronic device 1 where the entire YZ plane can be seen.

Referring back to FIG. Each light receiving element PD1
The forward input terminals of the PD 5 are all grounded, and the forward output terminals of the light receiving elements PD 1 to PD 5 are individually connected to a plurality of individual contacts of the switching circuit 42. Also, each light receiving element P
The forward output terminals of D1 to PD5 are connected to the power supply line 37 via the resistors R3 to R7 individually. Thus, a predetermined DC bias voltage is always applied to each of the light receiving elements PD1 to PD5. Therefore, each light receiving element P
D1 to PD5 can stably output an output current immediately after the switching circuits 42 and 51 are switched. The common contact Q of the switching circuit 42 is connected to one input terminal of the comparison circuit 43. A current / voltage conversion circuit (not shown) is interposed between the switching circuit 42 and the comparison circuit 43. A signal of a predetermined discrimination level is constantly supplied to the other input terminal of the comparison circuit 43. In the present embodiment, it is assumed that the discrimination level is the ground level. An output terminal of the comparison circuit 43 is connected to the demodulation circuit 34 as an output terminal of the reception circuit 27.

The switching circuit 42 conducts the common contact Q and any one of the specific individual contacts in response to a first switching control signal described later provided from the selection circuit 56 of the switching control circuit 44. This specific individual contact is provided for all light receiving elements PD1 to PD
The switching control circuit 44 is connected so that one of the light receiving elements having the best light receiving state among D5 is connected to the comparing circuit 43.
Selected by. As a result, a light amount signal of the specific light receiving element connected to the specific individual contact, which will be described later, is given to the comparison circuit 43. The comparison circuit 43 performs level discrimination of the applied light amount signal at a predetermined discrimination level, and generates a discrimination signal described later.

The switching control circuit 44 includes a switching circuit 51, a comparison circuit 52, a demodulation circuit 53, a ratio calculation circuit 54, a memory 5
5 and a selection circuit 56. Circuit 51
Since the structures of the circuits Nos. 53 to 53 are the same as those of the circuits 42, 43, and 34, and the behaviors of the circuits 52, 53 and the circuits 43, 34 are the same, detailed description will be omitted.

The switching circuit 51 has a common contact Q2 and a plurality of individual contacts. Each individual contact is
It is individually connected to the forward output terminal of PD5, and the common contact Q
2 is connected to the power supply line 37 via the current / voltage conversion resistor R2 and to one input terminal of the comparison circuit 52. The switching circuit 51 responds to a later-described second switching control signal supplied from the selection circuit 56,
2 and each individual contact are sequentially conducted. Switching circuit 51
Integrates the circuit 51 and the switching circuit 42 described above,
A configuration in which a plurality of individual contacts are shared may be employed.

The comparison circuit 52 receives the light quantity signal supplied from one of the light receiving elements via the switching circuit 51 and a current / voltage conversion circuit (not shown) at a predetermined discrimination level supplied from the other input terminal. A discrimination signal corresponding to the light amount signal is generated by discrimination, and the discrimination signal is demodulated by a demodulation circuit 5.
Give to 3. The demodulation circuit 53 demodulates the discrimination signal and supplies the obtained reception data signal to the ratio calculation circuit 54.

The ratio calculation circuit 54 calculates the error rate of the received data signal, and stores the error rate in the memory 55 in association with the light receiving element that outputs the light amount signal representing the received data signal. The ratio calculating circuit 54 includes the data converting circuit 2
5 also receives a received data signal.
The error rate of the received data signal is also calculated. This error rate is determined via the memory 55 or directly by the selection circuit 5.
6 given. The selection circuit 56 generates a second switching control signal for controlling the switching circuit 51 according to the operation of the switching control circuit 44 as described later. The switching circuit 42
Based on the error rate of the plurality of light reception data stored in the memory 55,
Generated as described below.

Hereinafter, the behavior of the optical communication device 23 during transmission will be described in detail.

First, the host device 22 gives a transmission data signal to be given to another electronic device to the register 31 of the data conversion circuit 25 and stores it. This transmission data signal is, for example, a digital signal including an error correction code. When the transmission data signal is stored in the register 31, the control circuit 32 supplies the transmission data signal to the modulation circuit 33. The modulation circuit 33 generates a modulated signal by modulating a predetermined carrier with a predetermined modulation method using the transmission data signal as a modulated signal. The signal level of the modulated signal changes at predetermined cycles in accordance with the value of the bit of the transmission data signal. The predetermined modulation method is, for example,
This is a modulation method suitable for the IrDA method of infrared communication.

The modulation signal output from the modulation circuit 33 is
The signal is input from the other connection terminal of the drive circuit 36 and supplied to the base terminal of the transistor T1. Transistor T1
Functions as a switching element, and connects or disconnects the connection between the forward connection terminal of the light emitting element LED2 and the ground line according to the signal level of the modulation signal. As a result, a current is supplied to or cut off from the power supply line 37 to the drive circuit 36 in response to the change in the signal level of the modulation signal to the light emitting elements LED1 and LED2. Therefore,
From the light emitting elements LED1 and LED2, light of an amount corresponding to the current is emitted intermittently in a pulse cycle corresponding to a change in the signal level of the modulation signal. By such a series of operations, the transmission circuit 26 transmits an optical signal whose light amount changes in accordance with the bit of the transmission data signal to the outside of the optical communication device 23.

Hereinafter, the behavior of the optical communication device 23 when receiving an optical signal will be described in detail.

All of the light receiving elements PD1 to PD5 individually receive light from outside the optical communication device 23 at all times, individually convert the received light into light, An output current whose current amount changes in response to aging is generated. When the S / N ratio between the optical signal and the optical noise is sufficiently small, the change in the amount of received light changes with the change in the amount of the optical signal transmitted from the optical communication device of another electronic device. I do.

The switching control circuit 44 includes the light receiving elements PD1 to PD1.
The light receiving state of the PD 5 is periodically compared by a method described later, and a specific light receiving element having the best light receiving state is selected. When the specific light receiving element is selected, the selection circuit 56 of the switching control circuit 44
A first switching control signal, which will be described later, is given to the switching circuit 42 to connect the specific individual contact among the plurality of individual contacts connected to the specific light receiving element to the common contact Q1. by this,
The output current from the specific light receiving element is first supplied to a current / voltage conversion circuit (not shown) through the switching circuit 42, and is converted into a light amount signal by the circuit. Then, this light amount signal is
It is provided to a comparison circuit 43. The light amount signal is, specifically,
The output current from the specific light receiving element is obtained by current / voltage conversion, and the amount of light received by the specific light receiving element is represented by a signal level.

When the light quantity signal from the specific light receiving element is given, the comparison circuit 43 discriminates the light quantity signal at a predetermined discrimination level and generates a discrimination signal representing a discrimination result. The comparison circuit 43 corresponds to a level adjusting unit in the claims. The discrimination signal is a rectangular pulse signal that maintains a high level when the signal level of the light quantity signal is equal to or higher than the discrimination level and maintains a low level when the signal level of the light quantity signal is less than the discrimination level. This is equivalent to the applied signal. Therefore, the discrimination signal is the S signal of the optical signal and the optical noise.
When the / N ratio is sufficiently small, a pulse is generated in response to a change in the amount of light of the optical signal received by the specific light receiving element. At this time, a change in signal level corresponding to optical noise has been removed from the discrimination signal.

The demodulation circuit 34 demodulates the discrimination signal generated by the comparison circuit 43 by a predetermined demodulation method to obtain a reception data signal. When the demodulation circuit 34 obtains the received data signal, the control circuit 32 temporarily stores the signal in the register 31 and then supplies the signal from the register 31 to the host device 22. The predetermined demodulation method is, for example, Ir communication of Ir.
This is a demodulation method compatible with the DA method. As described above, by using the discrimination signal for the demodulation operation of the demodulation circuit 34, the influence of optical noise superimposed on the optical signal can be removed as compared with the case where the light amount signal is used as it is.

FIG. 3 is a flowchart for explaining a specific operation of the switching control circuit 44 of the optical communication device 23 described above. The specific behavior of the switching control circuit 44 will be described with reference to FIGS.

When power is supplied to the optical communication device 23 and operation starts, the process proceeds from step a1 to step a2. In step a2, the selection circuit 56 substitutes an initial value of 1 into a variable i for counting the number of times of switching of the switching circuit 51 and initializes the variable i. Also, various variables used in the switching circuit 44 are all initialized. Next, in step a3, it is determined whether or not the value of the variable i is less than the number of the plurality of light receiving elements. In the present embodiment, specifically, it is determined whether it is less than 5. If it is less than 5, the operation of calculating the error rate after step a3 to step a4 is performed. If it is 5 or more, the operation of selecting the specific light receiving element after step a12 is performed.

In step a4, the selection circuit 56 demodulates the light amount signal from any one of the light receiving elements in response to the value of the variable i by the demodulation circuit 53. Specifically, first,
The selection circuit 56 generates the latest second switching control signal in the switching circuit 51 so that any one of the individual contacts corresponding to the value of the variable i and the common contact Q2 are connected. Give to. The value of the variable i is, for example,
In the order in which the plurality of individual contacts are arranged.
In this case, one of the individual contacts and the switching circuit 4
When the specific individual contacts connected to the two common contacts Q1 are connected to the same light receiving element, the individual contacts are skipped, and the individual contacts in the next order and the common contact Q2 are connected.
Generate the latest second switching control signal.

The switching circuit 51 switches an individual contact connected to the common contact Q2 in response to the applied second switching control signal. When the switching circuit 51 connects any one of the individual contacts to the common contact Q2, a light amount signal is supplied to the comparison circuit 52 from the light receiving element connected to the individual contact.
The comparison circuit 52 generates a discrimination signal by level discrimination of the light quantity signal, and supplies the discrimination signal to the demodulation circuit 53. The demodulation circuit 53
The discrimination signal is demodulated to obtain the latest received data signal corresponding to the light receiving element connected to any one of the individual contacts. The above operation of each of the circuits 51 to 53 is performed by the demodulation circuit 5
The operation is continuously performed until a reception data signal having a predetermined data amount is obtained in step 3. The predetermined data amount is, for example, 125 bytes, and is determined by counting the number of bits of the received data signal obtained by the demodulation circuit 53.

Subsequently, in step a5, the ratio calculation circuit 54 determines whether or not there is a data transmission error for each bit of the latest received data signal. The determination of the data transmission error is performed by an error correction operation using the error correction code when the received data signal includes an error correction code called parity, for example. If there is a transmission error in the bit to be determined, step a
In step 6, 1 is cumulatively added to the abnormal bit variable indicating the number of bits having a transmission error. If there is no transmission error in the bit to be determined, in step a7, 1 is cumulatively added to a normal bit variable representing the number of bits having no transmission error. The operations of steps a5 to a7 are repeatedly performed for all bits of the received data signal, and when the determination of the transmission error of all bits is completed, the process proceeds to step a8.

In step a8, the ratio calculation circuit 54
The latest error rate of the received data signal is calculated from the values of the abnormal bit variable and the normal bit variable of the received data signal calculated in steps a6 and a7. The error rate is a ratio between the total number of bits of the received data signal and the number of erroneous bits in the signal, and is represented by, for example, a ratio between a value of an abnormal bit variable and a value of a normal bit variable. . The calculated error rate is provided to the memory 55 from the ratio calculation circuit 54 and stored in step a9. At this time, data indicating any one of the light receiving elements connected to the comparison circuit 52 when the error rate is calculated is stored in association with the error rate. Further, the ratio calculation circuit 54 supplies a signal indicating that the latest error rate calculation has been completed to the selection circuit 56.

In step a10, the selection circuit 56 determines that the common contact Q2 of the switching circuit 51 is connected to one of the plurality of individual contacts corresponding to a value obtained by adding 1 to the current value of the variable i. A second switching control signal is generated so as to be connected, and supplied to the switching circuit 51. Switching circuit 51
Switches and connects the individual contacts in response to the latest second switching control signal provided. Thereby, the comparison circuit 5
2, a light amount signal from a light receiving element different from that at the time of calculating the above-described error rate is given. After the switching circuit 51 is switched, the selection circuit 56 updates by adding 1 to the variable i,
Thereafter, the process returns to step a3.

Thus, a series of operations for calculating the error rate from the comparison circuit 52 to the selection circuit 56 as performed in steps a3 to a11 are performed by the switching circuit 51.
The number of the individual contacts connected to the common contact Q2 is sequentially changed, and the number is repeated by one less than the number of the light receiving elements PD1 to PD5. Therefore, the memory 55 includes the light receiving element PD1
Error rates corresponding to the remaining light-receiving elements excluding the specific light-receiving element among PD5 through PD5 are sequentially stored at different addresses. While the operations of steps a3 to a11 are repeatedly performed, the common contact Q1 of the switching circuit 42 is always connected to any one specific individual contact. therefore,
During the operation for the above calculation, the comparison circuit 43 generates a discrimination signal from the light amount signal from the specific light receiving element, and the demodulation circuit 34 demodulates the discrimination signal to generate a reception data signal. .

When the value of the variable i is 5 or more in step a3, the memory 55 stores the error rate of the latest received data signal corresponding to the remaining light receiving elements other than the specific light receiving elements among the light receiving elements PD1 to PD5. Are all stored. At this time, the ratio calculation circuit 54
At 12, the latest light receiving data signal of a predetermined data amount is branched and introduced from the demodulation circuit 34, and the error rate of the light receiving data signal is calculated. The method of calculating the error rate is the same as the method of calculating steps a5 to a8. Thus, the error rate of the light receiving data signal obtained from the light amount signal from the specific light receiving element can be obtained. Therefore, when the processing in step a12 is completed, the light receiving elements PD1 to PD
All the latest error rates corresponding to 5 are obtained. The error rate of the received data signal corresponding to the specific light receiving element is stored in the memory 55 in the same manner as the error rate of the latest received data signal corresponding to the remaining light receiving elements. The error rate may be directly supplied from the ratio calculation circuit 54 to the selection circuit 56.

Next, at step a13, the selection circuit 56
First, all the error rates of the latest light receiving data signals corresponding to the light receiving elements PD1 to PD5 are read from the memory 55, and then the values of all error rates are compared. Is determined. Further, the light receiving element corresponding to the determined minimum error rate is selected as the specific light receiving element having the best light receiving state.

Subsequently, at step a13, the selection circuit 56
Generates the latest first switching control signal so that the common contact Q1 of the switching circuit 42 is connected to the specific individual contact to which the specific light receiving element selected by the selecting operation in step a13 is connected. It is given to the circuit 42. The switching circuit 42 switches and connects the individual contacts in response to the latest first switching control signal. As a result, the comparison circuit 43 is supplied with the light amount signal from the specific light receiving element selected by the latest selection operation in step a13. When the switching circuit 42 is switched,
The process returns from step a13 to step a2, and is initialized by substituting the initial value 1 for the variable i again. As a result, in the switching control circuit 44, the operation of calculating the error rate and the operation of selecting the specific light receiving element are performed alternately while the optical transmitter 23 is supplied with power and operates.

With such a series of operations, the switching control circuit 44 controls the switching circuit so that the light receiving element having the best reception state is always connected to the comparing circuit 43 based on the light amount signals from the light receiving elements PD1 to PD5. 42 can be controlled.

In the above-mentioned optical communication device 23, a specific light receiving element is selected based on the error rate of the received data signal. This is for the following reason. For example, I
In the infrared communication of the rDA system, an infrared signal is emitted in the form of a pulse, and the pulse generation pattern is changed in response to a bit value to generate an optical signal. When observing the change with time of the received light amount of PD5, the received light amount fluctuates irregularly. Therefore, in the case of an optical signal, the average value of the amount of light received by the light receiving element is not always constant, such as the intensity of the received electric field in the radio communication of FM broadcasting. Therefore, it is difficult to determine the quality of the light receiving state using the amount of received light as a parameter. Therefore, by using another parameter such as the error rate of the received data signal, the value of which increases or decreases in accordance with the quality of the light receiving state, the light receiving state can be changed in the same manner as when the received electric field strength of the radio communication is used. Can select the best light receiving element.

The switching control circuit 44 includes a comparison circuit 52 for obtaining a received data signal to be supplied to the host device 22 and a demodulation circuit 34, a comparison circuit 52 for calculating an error rate, and a demodulation circuit. 53 are prepared. Thereby, during the error rate calculation operation, the comparison circuit 43 and the demodulation circuit 34 perform the demodulation operation of the demodulation circuit 34 based on the light amount signal from the specific light receiving element separately from the operation of the switching control circuit 44. Therefore, the demodulation operation is not interrupted. Therefore, even when the light receiving state is selected using the error rate, the selection can be performed without affecting the operation for obtaining the reception data signal to be provided to the host device 22. Therefore, the comparison circuit 43 after the switching circuit 42, the data conversion circuit 25, and the host device 2
2 can be performed by the same operation as the operation of the comparison circuit, the data conversion circuit, and the host device of the optical communication device of the related art that does not use the diversity system.

Further, the switching control circuit 44 introduces the latest received data signal corresponding to the specific light receiving element from the demodulation circuit 34. Accordingly, when calculating the error rate of the latest received data signal corresponding to all the light receiving elements PD1 to PD5 in the switching control circuit 44, it is not necessary to demodulate the light amount signal from the specific light receiving element by the demodulation circuit 53. Therefore, the processing operation in the demodulation circuit 53 can be simplified. Further, the light amount signal from the specific light receiving element is transmitted to a demodulation circuit 5.
3, demodulation may be performed.

FIG. 4 shows the light receiving allowable azimuth region 4 of the light receiving elements PD1 and PD2 among all the light receiving elements PD1 to PD5.
It is a schematic diagram showing the positional relationship of 9,50. FIG. 4A is a diagram of the light-receiving allowable azimuth regions 49 and 50 as viewed in the X direction in which the light-receiving elements PD1 to PD5 are arranged in parallel, similarly to FIG. 2, and FIG. It is a schematic diagram showing the AA cross section of A). 2 and 4 will be described together.

As described above, the light receiving elements PD1, PD2
Are sequentially arranged in the X direction, and are arranged such that the directions of the normals 47 and 48 of the light receiving surface differ from each other by the mounting angle α in the YZ plane. At this time, ideally, the normal lines 47 and 48 which are the central axes of the light receiving allowable azimuth regions 49 and 50 are ideal.
Are preferably line segments on the same yz plane.

Two light emitting elements 61 and 62 are arranged as shown in FIGS. 2 and 4 with respect to the light receiving element PD1 thus arranged. The region 63 indicates the direction in which the light emitting element 62 emits an optical signal. The light emitting element 61 is arranged on an extension of the normal line 47 of the light receiving element PD1 such that its light emitting surface faces the light receiving surface of the light receiving element PD1. The light emitting element 62 is arranged so that its light emitting surface faces the light receiving elements PD1 and PD2 in directions different from the normal line 47 by an angle β in the YZ plane.
The angle β is an angle equal to or larger than the angle θ described above. The positional relationship between the light receiving element PD1 and the light emitting elements 61 and 62 is the same as the positional relationship between the light emitting elements 2 and 3 and the light receiving element 1 in the prior art described with reference to FIG.

In this case, the light emitting element 61 is
Since the optical noise source is included in the reception allowable angle region 49 and the optical signal source is not included in the region 49 and the optical signal from the optical communication device including the light emitting element 61 is received, Among the light receiving elements PD1 to PD5, the light receiving element PD
The light receiving state of 1 is the best. At this time, the light receiving element PD1
The light receiving amount of the optical signal at the light receiving elements PD2 to PD5 becomes stronger than the other light receiving elements PD2 to PD5. Therefore, it is considered that the error rate of the received data signal obtained by demodulating the light amount signal from the light receiving element PD1 by the demodulation circuit 53 is sufficiently smaller than the allowable error rate specified in the optical communication. The permissible error rate is a condition in data communication between the transmitting electronic device and the receiving electronic device in which the receiving electronic device cannot accurately reproduce the transmitted data signal as the received data signal, thereby causing a trouble in the communication. Is the minimum error rate. Specifically, the allowable error rate is about 10 ^-8 when IrDA infrared communication is used for data communication.

The light emitting element 62 is not included in the receivable angle region 49 of the light receiving element PD1,
2 are included in the receivable angle range 50. Therefore, when the source of the optical noise is not included in the area 50 and the optical signal from the optical communication device including the light emitting element 62 is received, of the light receiving elements PD1 to PD5, Element P
The light receiving state of D2 becomes the best. At this time, as in the case of the light emitting element 61 and the reception allowable angle region 49 described above,
It is considered that the error rate of the received data signal obtained by demodulating the light amount signal from the light receiving element PD2 by the demodulation circuit 53 is sufficiently smaller than the allowable error rate specified in the optical communication.

As described above, in the optical communication device of the present embodiment,
It is considered that the light-emitting element is included in any one of the light-receiving elements PD1 to PD5 in the receivable angle region. Therefore, any one of the plurality of light receiving elements PD1 to PD5 including the light emitting element in the receivable angle region.
If one light receiving element is selected as a specific light receiving element, when there is no source of optical noise in the receivable angle range,
A received data signal having a sufficiently low error rate can be obtained.

When an optical signal from an optical communication device including the light emitting element 61 is received, the light receiving angle range 49
When an optical noise source is present, the error rate of the received data signal obtained by demodulating the light amount signal from the light receiving element PD1 by the demodulation circuit 53 may be higher than the allowable error rate. In this case, the reception data signal obtained by demodulating the light amount signal from the light receiving element PD2 by the demodulation circuit 53 may have a lower error rate than the reception data signal from the light receiving element PD1. In such a case, the switching control circuit 44 selects the light receiving element PD2 as the specific light receiving element. Therefore, the switching control circuit 44 avoids the light receiving element PD1 directly facing the source of the optical noise, and starts from the light receiving element with little influence of the optical noise. The light receiving data signal can be obtained from the light amount signal of the second light source. Therefore, the influence of the optical noise on the received data signal, which is caused by the positional relationship between the source of the optical noise and the electronic device 21, can be reduced.

From these facts, the electronic device 21 of the present embodiment strictly positions the optical communication device of the electronic device on the transmitting side and the optical communication device 23 of the electronic device 21 on the receiving side as in the prior art. Even if not combined, optical communication with a sufficiently low error rate can be performed. Therefore, the transmitting and receiving electronic devices 21 incorporating this communication device 23 are
Irrespective of the positional relationship of. For example, when these electronic devices 21 are realized by a personal computer and its peripheral devices, the personal computer and the peripheral devices connected by optical wireless communication can be arranged so that the operator can easily operate them. The efficiency of work using these computers and peripheral devices can be improved. Therefore, the optical communication device 23 of the present embodiment has the advantages of optical communication that is not strictly regulated and has little effect on the human body as compared with radio wave communication, while maintaining the superiority of the optical communication on the transmission side and the reception side as described above. Device 21
Can be arranged arbitrarily. Also, this optical communication device
Compared to a diversity radio communication device, since a plurality of components such as light receiving elements to be prepared are small and power consumption is small, the manufacturing cost of the entire optical communication device is low and power consumption can be reduced. Furthermore, the optical communication device has a simple circuit configuration and low accuracy of circuit adjustment as compared with the above-described diversity radio communication device, and thus can be easily manufactured.

In the above-described optical communication device 23, when a transmission error occurs in the reception data signal, a defect occurs in the reception data signal. It cannot be obtained accurately by the optical communication device on the receiving side. At this time, the optical communication device 23 on the receiving side often causes the optical communication device on the transmitting side to retransmit a part of the optical signal including the portion where the transmission error of the received data signal has occurred. Therefore, when the error rate is higher than the allowable error rate, the amount of retransmission of the optical signal becomes extremely large, and it takes time to retransmit. Therefore, since the communication time required for one optical communication becomes long, the operator of the electronic device 21 often feels inconvenience. In the optical communication device 23 of the present invention, the optical communication device 2 on the transmission side and the reception side
It is possible to prevent an increase in the error rate caused by the mismatch of the position 3 and an increase in the error rate caused by the positional relationship between the optical communication device 23 on the receiving side and the source of the optical noise. Therefore, when the optical communication device on the transmitting side is in any direction with respect to the optical communication device 23 on the receiving side,
By reducing the number of retransmissions, it is possible to prevent an increase in communication time required for one optical communication.

FIG. 5 is a block diagram showing an electrical configuration of an electronic device 81 including an optical communication device 82 according to the second embodiment of the present invention. The electronic device 81 includes a host device 22 and an optical communication device 82, like the electronic device 21.
Has a structure similar to the optical communication device 23, the structure of the receiving circuit is different, and the structure and behavior of the remaining circuit components are the same. Circuit components having the same structure and behavior are given the same reference numerals,
Description is omitted.

The receiving circuit 84 includes a plurality of receiving elements, the switching circuit 42, and a switching control circuit 86. In the present embodiment, it is assumed that five receiving elements U1 to U5 are included.

The receiving elements U1 to U5 have one connection terminal all grounded and the other connection terminal individually connected to a plurality of individual contacts of the switching circuit 42. The common contact Q1 of the switching circuit 42 is directly connected to the demodulation circuit 53 of the data conversion circuit 25. The switching circuit 42 is connected to the selection circuit 56 of the switching control circuit 86.
Is controlled by a first switching control signal given by

Each of the receiving elements U1 to U5 is a so-called IR communication unit.
Is shown in FIG. 6 as an example. The receiving element U1 is a light receiving element PD
11, a current / voltage conversion circuit 88, and a comparison circuit 89. The forward input terminal of the light receiving element PD11 is grounded, and its forward output terminal is connected to the input terminal of the current / voltage conversion circuit 88. Current / voltage conversion circuit 88
Is connected to one input terminal of the comparison circuit 89. A signal of a predetermined discrimination level is always supplied to the other input terminal of the comparison circuit 89. The output terminal of the comparison circuit 89 serves as the output terminal of the receiving element U1,
It is connected to any one of the plurality of individual contacts. The comparison circuit 89 corresponds to a level adjusting means in the claims.

The light receiving element PD11 and the comparing circuit 89 are the same as the light receiving elements PD1 to PD5 and the comparing circuit 43 of the first embodiment.
52, and the current / voltage conversion circuit 88
The receiving circuit 27 of the first embodiment operates similarly to the current / voltage conversion circuit not shown. Therefore, the receiving element U1
Is the receiving circuit 27 of the first embodiment, the comparison circuit 43,
An electric circuit including a specific light receiving element connected to the circuit via a switching circuit 42, and one of the resistors R3 to R7, a comparison circuit 43, and a switching circuit 5 connected to the circuit;
1 operates in the same manner as an electric circuit composed of any one of the light receiving elements connected through the light receiving element 1 and the resistor R2.
A light amount signal whose signal level changes in response to the amount of received light of No. 11 is generated. The specific electrical structure of the receiving elements U2 to U5 and the connection with the switching circuit 42 are
Since it is equal to 1, the description is omitted.

The receiving elements U1 to U5 are formed integrally with the electric circuit shown in FIG. These receiving elements U1
To U5 are arranged in parallel on a virtual axis along a predetermined X direction parallel to the light receiving surfaces of the light receiving elements in the receiving elements U1 to U5, and the normal of the light receiving element in each of the receiving elements U1 to U5. Are arranged so as to face mutually different directions. For example, the receiving elements U1 and U2 are, as shown in FIGS. 7 and 8, light receiving elements PD11 and P2 in each of the receiving elements U1 and U2.
The normal lines 94 and 95 of the light receiving surfaces 93 and 92 of D12 are arranged so as to intersect at an attachment angle α when viewed from the X direction. Acceptable light receiving azimuth areas 96, 9 of light receiving elements PD11, PD12
Reference numeral 7 denotes a region within a cone having an angle θ with the normals 94 and 95 of the light receiving surfaces 93 and 92 as central axes. The aforementioned mounting angle α is selected to be less than twice the angle θ.

2θ> α (1) The light receiving elements PD11 and PD12 are circuit components equivalent to the light receiving elements PD1 and PD2 of the first embodiment, and the positional relationship between the receiving elements U1 and U2 is PD1
The two light-receiving permissible azimuth regions 97 and 96 may be arranged so as to maintain the same positional relationship as the light-receiving permissible azimuth regions 49 and 50 of the light receiving elements PD1 and PD2. The arrangement relation between the other reception elements U3 to U5 and the light reception elements U2 to U4 is equal to the arrangement relation between the light reception elements U1 and U2 described above. As a result, the light receiving elements U1 to U5 are sequentially shifted in direction by the mounting angle α around the virtual axis. The angle θ of the light receiving permissible surrounding area of each light receiving element is, for example, 45 degrees, and the mounting angle α at this time is
Is selected, for example, at 80 degrees.

As a result, the light receiving permissible azimuth regions of the light receiving elements U1 to U5 overlap by 10 degrees in the YZ plane and include the entire YZ plane. In this case, ideally, it is preferable that the normal lines 47 and 48 which are the central axes of the light-receiving permitted azimuth regions 49 and 50 be line segments on the same yz plane.

Referring back to FIG. Switching control circuit 86
Are generated from a switching circuit 51, a demodulation circuit 53, a ratio calculation circuit 54, a memory 55, and a selection circuit 56. The plurality of individual contacts of the switching circuit 51 are individually connected to the other connection terminals of the receiving elements U1 to U5, and the common contact Q2 is connected to the demodulation circuit 5
3 is directly connected. The circuit structure and behavior after the demodulation circuit 53 are the same as those of the switching control circuit 44 of the first embodiment.

As described above, the optical communication device 82 of the second embodiment
Are the receiving elements U1 to U5 instead of the light receiving elements PD1 to PD5.
U5 is attached, and the comparison circuits 43 and 52 and the resistor R
1 and R2, and the other structure is the same as that of the optical communication device 23. The optical communication device 81 includes a data conversion circuit 2
5 and the operation of the transmission circuit 26 are the same as those of the optical communication device 21 of the first embodiment. In the receiving circuit 84, the optical communication device 21
Instead of selecting the specific light receiving element and any one of the light receiving elements and generating the first and second switching control signals, the selection circuit 56 selects the specific receiving element and any one of the receiving elements and performs the first and second switching. The point at which the control signal is generated is that instead of supplying the discrimination signal generated by current / voltage conversion of the output current from the light receiving element selectively connected by the switching circuits 42 and 51 and then level discrimination to the demodulation circuit 3453, the switching circuit 42 The difference is that the discrimination signal from the specific receiving element selectively connected at 51 is directly supplied to the demodulation circuits 34 and 53, but other behaviors are the same.

The optical communication device 82 includes demodulation circuits 34 and 53
When a received data signal is obtained by the optical communication device 23, the current from the light receiving elements PD1 to PD5 is supplied to a current / voltage conversion circuit (not shown) via the switching circuits 42 and 51 and converted into a light amount signal by the optical communication device 23. The operation that was discriminating the level by
This is performed in the receiving elements U1 to U5. Therefore, the light receiving element PD1
The operation from receiving light at 1 to generating a discrimination signal can be performed in parallel by each of the receiving elements U1 to U5. Therefore, when the switching circuit 86 calculates the error rate from the received data signal corresponding to each light receiving element, the discrimination signal is given from the receiving elements U1 to U5. Therefore, compared with the case where the current / voltage conversion operation and the level discrimination operation are sequentially performed before the demodulation operation as in the optical communication device 23 of the first embodiment, the optical communication device 82 of the second embodiment has The processing operation in the switching control circuit 86 can be simplified and the processing time can be shortened.

The receiving element U arranged as described above
The positional relation between the light receiving elements 1 to U5 and the positional relation between the light receiving azimuth regions thereof are as described in the first embodiment.
It is equal to the positional relationship of D5 and the positional relationship of the receivable azimuth region. Therefore, the light emitting elements 61, 62 arranged in the same manner as in FIGS.
When receiving the light signal from the light receiving elements U1 to U5, the light receiving state of the light receiving elements PD11 and PD12 included in the receivable azimuth region of the light emitting elements 61 and 62 among the light receiving elements U1 to U5 is the best. At this time, the light receiving elements PD11, PD1
It is considered that the error rate of the received data signal obtained by demodulating the discrimination signals from the receiving elements U1 and U2 including the signal No. 2 by the demodulation circuit 53 is sufficiently smaller than the allowable error rate specified in the optical communication.

Therefore, the optical communication device 81 of the second embodiment
If the receiving elements U1 and U2 including the light receiving elements PD11 and PD12 described above are selected as the specific receiving elements, the transmitting optical communication apparatus and the receiving optical communication apparatus can be used similarly to the optical communication apparatus 21 of the first embodiment. Irrespective of the positional relationship, the optical signal can always be received in the best light receiving state.

Furthermore, when receiving an optical signal from an optical communication device including the light emitting element 61, the reception allowable angle area 96
When there is a source of optical noise inside, the switching control circuit 86 selects the receiving element U2 including the light receiving element PD12 as the specific receiving element. As a result, the reception signal U can be obtained by demodulating the discrimination signal from the reception element U2 which is less affected by the optical noise while avoiding the reception element U1 directly facing the source of the optical noise. Therefore, the influence of the optical noise on the received data signal, which is caused by the positional relationship between the source of the optical noise and the electronic device 81, can be reduced. Further, in general, the receiving element has higher strength against optical noise than the light receiving element alone. Therefore, as in the first embodiment, the light receiving elements PD1 to PD
Arranging the receiving elements U1 to U5 can further reduce the influence of optical noise than arranging D5 alone.

Therefore, the optical communication device 82 of the second embodiment
As with the optical communication device 21 of the first embodiment, data communication superior to radio wave communication can be performed regardless of the arrangement of the electronic devices on the transmission side and the reception side. Also,
An optical communication device having a simpler circuit structure, lower accuracy, and lower manufacturing cost than a diversity type radio communication device can be realized. Furthermore, the optical communication device of the present embodiment is
As in the first embodiment, it is possible to suppress an increase in the error rate due to the positional relationship between the sources of the optical signal and the optical noise. Furthermore, when an amplifier circuit for amplifying an output current or a light amount signal from the light receiving element is provided in the optical communication device,
In the optical communication device of the present embodiment, the amplifier circuit includes the receiving elements U1 to U1.
It is provided in U5. Therefore, as compared with the optical communication device of the first embodiment, in the optical communication device of the second embodiment, since the wiring distance between the light receiving element and the amplifier circuit is short, noise mixed from the wiring is small, and the signal Is less deteriorated. Thus, an optical communication device using a receiving element is more resistant to optical noise than an optical communication device using a light receiving element. From these, the error rate increases beyond the allowable error rate,
It is possible to prevent the transmission time of data communication from becoming excessively long.

[0074]

As described above, according to the present invention, an optical communication device receives an optical signal by a so-called diversity system. Accordingly, a change in the light receiving condition caused by the positional relationship between the light receiving unit of the optical communication device on the receiving side and the light emitting unit of the optical communication device on the transmitting side, and the light receiving unit of the optical communication device on the receiving side and the optical The optical signal can always be received under the best reception conditions regardless of the change in the light reception conditions caused by the positional relationship with the source of the target noise.

Further, according to the present invention, the selection means of the optical communication device includes a data signal obtained by demodulating an output signal from each light receiving means as a parameter for selecting a light receiving means in the best light receiving state. Is used. This makes it easy to select the receiving means with the best reception condition in a diversity optical communication device using an optical signal that does not have a parameter for comparing the light reception condition such as the reception electric field strength in radio communication. can do.

Further, according to the present invention, the optical communication device comprises:
The light receiving levels of the signals from the plurality of light receiving means are selected after being adjusted by the level adjusting means provided for each of the light receiving means, and are provided to the signal demodulating means for demodulation. by this,
At the time of demodulation operation by the signal demodulation means, it is hardly affected by optical noise mixed into the optical signal, and a data signal can be obtained reliably.

Further, according to the present invention, the optical communication device selects signals from the plurality of light receiving means, adjusts the light receiving levels of the selected signals, and demodulates the signals by the signal demodulating means. This makes it less susceptible to optical noise during the demodulation operation, and can reduce the number of components as compared with an optical communication device having a level adjusting means for each light receiving element.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an electrical configuration of an electronic device 21 including an optical communication device 23 according to a first embodiment of the present invention.

FIG. 2 shows the positional relationship between the light receiving elements PD1 and PD2 in the optical communication device 23, and the light receiving elements PD1 and PD2 and the light emitting element 61;
It is a schematic diagram showing the positional relationship of 62.

FIG. 3 is a flowchart showing a specific operation of a switching control circuit 44 of the optical communication device 23.

FIG. 4 shows the positional relationship between the light receiving elements PD1 and PD2 in the optical communication device 23 and the light receiving elements PD1 and PD2 and the light emitting element 61;
It is a schematic diagram showing the positional relationship of 62.

FIG. 5 is a block diagram illustrating an electrical configuration of an electronic device 81 including an optical communication device 82 according to a second embodiment of the present invention.

FIG. 6 is a block diagram illustrating a specific electrical configuration of a receiving element U1 of the electronic device 81.

FIG. 7 is a schematic diagram showing a positional relationship between the receiving elements U1 and U2 in the optical communication device 82 and a positional relationship between the receiving elements U1 and U2 and the light emitting elements 61 and 62.

FIG. 8 is a schematic diagram showing the positional relationship between the receiving elements U1 and U2 in the optical communication device 82 and the positional relationship between the receiving elements U1 and U2 and the light emitting elements 61 and 62.

FIG. 9 is a schematic diagram illustrating a positional relationship between the light receiving element 1 and the light emitting elements 2 and 3 in the optical communication device.

FIG. 10 shows a receiving element 10 and light emitting elements 2 and 3 in an optical communication device.
It is a schematic diagram showing the positional relationship with.

[Explanation of symbols]

 21, 81 Electronic device 23, 82 Optical communication device 27, 84 Reception circuit 34, 53 Demodulation circuit 42, 51 Switching circuit 43, 52; 89 Comparison circuit 54 Ratio calculation circuit 55 Memory 56 Selection circuit PD1 to PD5; PD11, PD12 Light reception Element U1 to U5 Receiver element

Claims (4)

[Claims] 1. An optical communication device for transmitting and receiving an optical signal representing a predetermined data signal using light, comprising: a plurality of light receiving means for individually receiving the optical signal under mutually different light receiving conditions; Among the means, there is provided a selecting means for selecting the light receiving means having the best light receiving state, and a first demodulating means for demodulating an output signal output from the light receiving means selected by the selecting means to obtain the data signal. An optical communication device, characterized in that: 2. An optical communication device comprising: a second demodulation unit that demodulates the output signal output from each of the light receiving units to obtain a data signal corresponding to each of the light receiving units; For each demodulated data signal, further comprising a ratio calculating means for calculating a ratio between the total data amount of the data signal and the erroneous data amount, wherein the selecting means comprises: 2. The optical communication device according to claim 1, wherein the light receiving unit corresponding to the data signal having the smallest ratio calculated by the calculating unit is selected. 3. An optical communication device for transmitting and receiving an optical signal representing a predetermined data signal by an amount of light, comprising: a plurality of light receiving means for individually receiving the optical signal under mutually different light receiving conditions; A plurality of level adjusting means for individually adjusting the light receiving level of the signal output from the corresponding light receiving means, and among the plurality of adjusted signals, the light receiving state is best among the plurality of light receiving means. An optical communication device comprising: a signal selecting unit that selects a signal adjusted by a level adjusting unit corresponding to the light receiving unit; and a signal demodulating unit that demodulates the selected signal to obtain the data signal. . 4. An optical communication device for transmitting and receiving an optical signal representing a predetermined data signal by an amount of light, comprising: a plurality of light receiving means for individually receiving the optical signal under mutually different light receiving conditions; Selecting means for selecting the light receiving means having the best light receiving condition, level adjusting means for adjusting the light receiving level of the signal output from the light receiving means selected by the selecting means, demodulating the adjusted signal; A signal demodulation means for obtaining the data signal.