JPH0865243A - Optical communication equipment - Google Patents

Abstract

PURPOSE: To provide the optical communication equipment, with which data can be received with high reliability even under the condition of low light receiving power or high surrounding light, concerning the optical communication equipment due to radio between computer terminal equipment or the like. CONSTITUTION: A permeability varying device 3a7 to change permeability corresponding to light intensity and an irradiated position varying device 3a8 to make different the irradiated position of this permeability varying device 3a7 corresponding to the direction of incident light are provided in front of a light receiver 3a11 inside a receiving part 3a4, and the threshold value of light intensity to considerably change the permeability of the permeability varying device 3a7 is set at light intensity to be considerably affected by noise due to that threshold value. Thus, the permeability of the permeability varying device 3a7 is changed at positions 3a9 and 3a10 strongly irradiated with sunlight 3a5 or illumination light 3a6 being surrounding light, and the irradiation of the light receiver 3a11 with the sunlight 3a5 or illumination light 3a being the surrounding light can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless optical communication device using light as a carrier wave between computer terminal devices and the like.

[0002]

2. Description of the Related Art In recent years, as represented by LAN (Local Area Network) and the like, network communication technology for exchanging information between computer terminal devices and the like is rapidly developing. Moreover, in particular, with the increase in speed of computer terminal devices, communication devices capable of high-speed communication using light as a carrier wave are rapidly attracting attention. In addition, a communication device capable of high-speed communication is also demanded due to a situation in which portable terminal devices are widely used due to the progress of personalization.

As a conventional optical communication device, a wireless communication device using a fiber cable or a wireless data communication device using infrared rays has been proposed.

FIG. 10 shows a typical example of a wireless optical communication device using a fiber cable. According to this optical communication device,
The infrared ray α2 emitted from the light emitter α1 on the data transmission side is condensed as much as possible by the lens α3 on the front surface of the light emitter α1, and is incident on one fiber end α4 of the fiber cable α5. As a result, infrared rays are transmitted through fiber cable α5
After being transmitted, it is emitted from the fiber end α6 on the other data receiving side.

After that, the infrared ray α7 emitted from the fiber end α6 on the data receiving side is condensed as much as possible by the lens α8 and is received by the photoreceptor α9.

As a result, the infrared ray α2 is modulated by the data transmitting side by various methods, and the infrared ray α7 is demodulated by the receiving side to perform optical communication. Since this method has a low loss in the fiber cable α5, it has an advantage that the loss in the optical power transmission system can be suppressed to within 10 dB.
Since it is wired, it has a drawback that it cannot be applied to terminal devices that are frequently moved such as portable terminal devices.

11 and 12 show an optical communication device using infrared rays as a carrier wave, as an example of a conventional wireless optical communication device. First, the optical communication device using infrared rays of the direct propagation type shown in FIG. 11 will be described. The infrared ray β5 emitted from the infrared ray emitter β1 is condensed on the infrared ray receptor β2 as much as possible by using the condenser lens β3 in front of the infrared ray emitter β1 and the condenser lens β4 in front of the infrared ray receiver β2. Optical communication is performed by modulating the infrared ray β5 by various methods.

This optical communication device has an advantage that it can perform data communication by radio and that the loss of optical power in the transmission system can be suppressed within several tens of dB.

However, the optical communication requires a line of sight between the transmitting side and the receiving side, and there is an obstacle or the like that blocks the infrared ray β5 between the infrared light emitting body β1 and the infrared light receiving body β2. It has a drawback that data transmission is interrupted when an object passes through. Further, the infrared light emitter β1 and the infrared light receiver β2 need to be precisely aligned manually, which is a drawback that it is difficult to use for a portable terminal device whose position changes frequently.

Next, the diffusion propagation type optical communication device shown in FIG. 12 will be described. An infrared ray γ3 having a wide divergence angle γ6 emitted from the infrared light emitting device γ1 is once radiated to, for example, a wall or ceiling γ5, and an infrared ray γ4 reflected or diffused from the wall or ceiling γ5 is received as an infrared ray having a wide divergence angle γ7. It is used in the form of receiving light by the light receiving device γ2, and this infrared ray is modulated by various methods to perform optical communication.

In this optical communication device, the optical communication device can be wirelessly used like the optical communication device shown in FIG. 11, and unlike the optical communication device shown in FIG. Even if there is an obstacle that blocks the propagation of infrared rays on the straight line connecting the infrared light receiving device γ2, data communication will not be hindered.

Therefore, as compared with the optical communication device shown in FIG. 11, it has an advantage that it is suitable for a mobile terminal such as a mobile terminal that is frequently moved.

[0013]

However, in the above-mentioned diffusion propagation type optical communication device, since the diffusion propagation is used, the loss in the transmission system of the optical power is as large as 60 dB or more, and the infrared receiving device γ2 is used. For example, since it is easy to receive ambient light such as illumination light and sunlight, the shot noise of the infrared light receiving device is greatly increased.
As a result, the error rate increases, and there is a drawback that high-speed optical communication is difficult.

As described above, in a wireless infrared optical communication device which can be used in a portable terminal device as well, it is necessary to take into consideration a large loss of optical power and an increase in shot noise due to the influence of ambient light. The communication speed could not be increased.

In view of the above problems, an object of the present invention is to provide a wireless optical communication device between computer terminal devices and the like, which is capable of receiving data with high reliability even under conditions of low received light power and high ambient light. To provide.

[0016]

In order to achieve the above-mentioned object, the present invention provides an optical communication device for wirelessly transmitting and receiving an optical signal according to claim 1, wherein a receiving sensitivity is set in a receiving section for each incident direction of light. We propose an optical communication device provided with a receiving sensitivity varying means for changing the.

A second aspect of the present invention proposes an optical communication device according to the first aspect, which is provided with an irradiation position conversion means for converting the irradiation position of the light to the receiving section into a predetermined position.

According to a third aspect of the present invention, in the optical communication device according to the first or second aspect, the receiving sensitivity varying means includes a varying means for varying the transmittance or the reflectance in accordance with the light intensity. Optical communication device is proposed.

According to a fourth aspect of the present invention, in the optical communication device according to the first or second aspect, the reception sensitivity varying means has a plurality of light receivers, and the attenuation factors of the outputs of the plurality of light receivers. We propose an optical communication device equipped with an attenuator that changes the respective values.

According to a fifth aspect of the invention, there is provided the optical communication apparatus according to the second aspect, wherein the irradiation position conversion means is a pinhole or a lens.

According to a sixth aspect of the present invention, in the optical communication apparatus according to the third aspect, the variable means for changing the transmittance or the reflectance according to the light intensity is an optical communication apparatus including a photochromic substance. suggest.

According to a seventh aspect, in the optical communication device according to the third aspect, the variable means for changing the transmittance or the reflectance in accordance with the light intensity is a converter for converting the light intensity into a voltage or a current. And an optical communication device including a variable device that changes the transmittance or reflectance of incident light based on the voltage or current.

According to claim 8, in the optical communication device according to claim 4, the attenuation means for changing the attenuation factors of the outputs of the plurality of photodetectors respectively include an optical communication device including a switch circuit or a clip circuit. suggest.

A ninth aspect of the present invention proposes an optical communication apparatus according to any one of the first to eighth aspects, which uses infrared rays as a carrier wave used for communication.

[0025]

According to the first aspect of the present invention, the receiving sensitivity varying means changes the receiving sensitivity for each incident direction of light. As a result, it becomes possible to weaken the reception sensitivity of ambient light other than the signal light incident from the unnecessary direction.

Further, according to the second aspect, the irradiation position conversion means converts the irradiation position of the light to the receiving portion into a predetermined position. As a result, the irradiation positions of the signal light and the ambient light are set to different positions. For example, the irradiation position of the signal light is the position of the light receiver, and the irradiation position of sunlight or illumination light other than the signal light is the position other than the light receiver.

Further, according to the third aspect, the light transmittance or the reflectance is changed by the variable means according to the light intensity of the incident light. Thus, for example, if the transmittance or reflectance is changed by the variable means so as to attenuate light such as ambient light whose light intensity is weaker than the signal light, the variable light is transmitted through the variable means or reflected by the variable means. Most of the light incident on the light receiver becomes signal light, and ambient light other than signal light is removed.

According to a fourth aspect of the present invention, the attenuation rate of the output of each of the plurality of light receivers is changed by the attenuation means. Thus, for example, if the amount of attenuation of the output of the light receiver on which ambient light other than the signal light is incident is set to be large, ambient light components other than the signal light are removed.

Further, according to the fifth aspect, the irradiation position of the light to the receiving portion is converted into a predetermined position by the pinhole or the lens, and, for example, the irradiation position of the signal light is set to the position of the light receiver, and other than the signal light The irradiation position of sunlight or illumination light is set to a position other than the light receiver.

According to the sixth aspect, the photochromic substance provided in the variable means changes the transmittance or reflectance of light in accordance with the light intensity of incident light. Thereby, for example, if the transmittance or the reflectance is changed so as to attenuate the light such as the ambient light whose light intensity is weaker than the signal light, the light is transmitted through the variable means or reflected by the variable means to the light receiver. Most of the incident light becomes signal light, and ambient light other than signal light is removed.

According to a seventh aspect, the light intensity is converted into a voltage or a current by a converter provided in the variable means,
The transmittance or reflectance of incident light is changed by the variable device based on the voltage or current. Thus, for example, if the transmittance or reflectance is changed by the variable means so as to attenuate light such as ambient light whose light intensity is weaker than the signal light, the variable light is transmitted through the variable means or reflected by the variable means. Most of the light that enters the light receiver becomes signal light,
Ambient light other than the signal light is removed.

According to the eighth aspect, the attenuation rate of the output of each of the plurality of light receivers is changed by the switch circuit or the clipping circuit included in the attenuation means. Thus, for example, if the amount of attenuation of the output of the light receiver on which ambient light other than the signal light is incident is set to be large, ambient light components other than the signal light are removed.

According to the ninth aspect, infrared rays are used as a carrier wave used for communication.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the embodiments described below, an example using infrared rays as a carrier wave for communication will be described. However, even when light having a shorter wavelength than infrared rays is used,
It is clear that there is a similar effect.

FIG. 1 is a block diagram of a main part of a light receiving device in an optical communication device according to claim 1 of the present invention. The outline of the present invention will be described with reference to FIG.

In FIG. 1, an infrared ray 13 carrying data transmitted from an optical communication apparatus (not shown) on the transmitting side is received by a receiving section 12 of the optical communication apparatus 11 on the receiving side for optical communication. . However, in addition to the infrared rays 13 on which the data is placed, the ambient light such as the sunlight 14 and the illumination light 15 are simultaneously incident on the receiving unit 12. Receiving this ambient light together with the infrared ray 13 for optical communication causes a noise increase in the light receiver in the receiving unit 12 as described below, and impedes the speedup of optical communication.

Now, the relationship between ambient light and noise will be described.
The main noise that becomes a problem in the light receiving portion in high-speed optical communication by wireless of 1 Mbps or more is generated from, for example, PD (photodiode), APD (avalanche photodiode) or PCD (photoconductive device) used in the light receiver. There are shot noise and thermal noise generated from resistors and amplifiers used in the subsequent stage.

Here, the thermal noise becomes a problem when the received light power is low and a sufficient photocurrent cannot be obtained by only simple photoelectric conversion. However, in this case, for example, by increasing the light receiving area to N times (N ≧ 1) or using a photodetector having a self-multiplying action such as including APD or PCD,
Since the signal can be multiplied by M times (M ≧ 1), thermal noise can be suppressed to 1 / N or 1 / M times.

On the other hand, the shot noise is about N (M
Since it is amplified by + α) times (α> 0), it cannot be suppressed by such a method. Moreover, this shot noise increases almost in proportion to the optical power incident on the light receiver, so when the light receiver captures ambient light together with infrared light for optical communication,
Ambient noise significantly increases shot noise. In particular, sunlight, light emitted from an incandescent lamp, and the like give strong light to the light receiver from the visible region to the infrared region as shown in FIG.
It was a big problem. This has been a serious problem that impedes speeding up until now.

Therefore, in this embodiment, the infrared ray 13 for optical communication is used.
For the reception sensitivity Q in the direction of
4 and the illuminating light 15 in the direction of the reception sensitivity Q
By attenuating / P4 and Q / P5 (P4, P5 ≧ 1), the adverse effect of ambient light noise on the reception of the infrared light 13 for optical communication in the receiving unit 12 is suppressed. This enables high-speed optical communication.

Here, in order to attenuate the ambient light as much as possible and not to attenuate the infrared light 13 for optical communication, the difference in light intensity between the ambient light and the infrared light 13 for optical communication, or the difference in the frequency of light intensity change, It is conceivable to use different wavelengths or a combination of these.

For example, when the difference in light intensity is used,
By setting the light intensity that greatly attenuates the reception sensitivity to an intensity at which the intensity of the ambient light has a great adverse effect on the reception of the infrared ray 13 for optical communication, the ambient light is attenuated as much as possible and the infrared ray 13 for optical communication is not attenuated. It becomes possible.
Further, when data is communicated by the intensity modulation of the infrared ray 13 for optical communication, the difference in frequency of light intensity change is used.
It is possible to set the attenuation of the infrared ray 13 for optical communication so that it mainly occurs in the frequency region of the intensity change of ambient light.

This is possible, for example, by setting the frequency of light intensity change that causes attenuation of reception sensitivity sufficiently lower than the frequency of intensity modulation because the frequency of intensity modulation is high when the optical communication speed is high. Become. Further, when using a difference in light wavelength, it is possible to set the light wavelength of the infrared light for optical communication to a light wavelength at which the intensity of ambient light does not have a large adverse effect on the reception of the infrared light for optical communication. .

Here, when data is communicated by intensity modulation of the infrared ray 13 for optical communication, in order to distinguish it from the signal for optical communication, the speed at which the reception sensitivity is attenuated is set to the infrared ray 1 for optical communication.
It is necessary to set the speed so that it hardly affects the frequency domain of the intensity modulation of No. 3. For example, when the optical communication speed is high, the frequency of the intensity modulation is high, so that the attenuation of the reception sensitivity can be set sufficiently lower than this frequency.

Further, in the configuration shown in FIG. 1, when the infrared ray 13 for optical communication enters from the same direction as the ambient light, for example, the sunlight 14 or the illumination light 15, this infrared ray 13 is also attenuated, so that the reception is performed. Can be difficult. Of course,
Even in the normal reception not according to the present invention, when the infrared light 13 for optical communication and the high-intensity ambient light are incident from the same direction, shot noise becomes large and reception is difficult, but the infrared light for optical communication in the present embodiment. In order to reduce the direction in which 13 cannot be received, it is extremely useful to set the light intensity that greatly attenuates the reception sensitivity as described above to the intensity at which the intensity of the ambient light has a great adverse effect on the reception of the infrared ray 13 for optical communication. .

Here, in a normal office environment, the infrared rays 13 for optical communication hardly enter from the window side where the sunlight 14 enters, and the illumination light 15 has a very weak intensity in the infrared region. Considering that most of the light lamps are used, there is no big impact.

FIG. 3 and FIG. 4 are main part configuration diagrams of a light receiving device in an optical communication device according to claims 2 and 3 of the present invention. In FIG. 3, an infrared ray 3a2 carrying data arrived from an optical communication device (not shown) on the transmitting side is received by a receiving section 3a4 of the optical communication device 3a3 on the receiving side for data communication. In this case, the sunlight 3a5, the illumination light 3a6, and the like are simultaneously input to the receiving unit 3a4 as ambient light.

Here, in the present embodiment, the transmittance varying device 3a7 whose transmittance changes according to the light intensity, and the irradiation position for changing the irradiation position to this transmittance varying device 3a7 in accordance with the direction of the incident light. The variable device 3a8 is provided in front of the light receiver 3a11 in the receiver 3a4.

Further, the threshold value of the light intensity at which the transmittance of the transmittance varying device 3a7 greatly changes is set to the light intensity at which the noise due to light has a great influence, or the frequency range of the intensity modulation of the infrared ray 3a2 for optical communication. Is set so that it mainly occurs in the frequency range of the intensity change of the ambient light, or the optical wavelength of the infrared light for optical communication is set to an optical wavelength at which the intensity of the ambient light does not have a large adverse effect on the reception of the infrared light for optical communication. Either set or set as a combination thereof.

As a result, the positions 3a9 and 3a10 where the ambient light such as the sunlight 3a5 and the illumination light 3a6 are strongly irradiated.
In, the transmittance of the transmittance varying device 3a7 changes,
Ambient light such as sunlight 3a5 or illumination light 3 is received by the light receiver 3a11.
Since it is possible to suppress irradiation of a6 and the like, and the infrared ray 3a2 for optical communication irradiates the transmittance varying device 3a7, the transmittance at the position 3a12 is hardly attenuated.
Infrared ray 3a2 for optical communication is placed at position 3a1 of light receiver 3a11.
Light can be received at 3.

Further, as shown in FIG. 4, the irradiation position changing means for changing the irradiation position to the reflectance changing device 3b7 whose reflectance changes depending on the light intensity and the incident light direction according to the direction of the incident light. By providing the device 3b8 in front of the light receiver 3b11 in the receiving unit 3b4 similar to that described above, the reflectance varying device 3b7 is provided at the positions 3b9, 3b10 irradiated by the ambient light such as the sunlight 3b5 and the illumination light 3b6. It is possible to suppress the reflectance from changing and to irradiate the light receiver 3b11 with the ambient light such as the sunlight 3b5 and the illumination light 3b6. As a result, it is possible to suppress noise, which has been a hindrance to data reception until now, and it is possible to speed up optical communication.

FIG. 5 is a configuration diagram of a main part of a light receiving device in an optical communication device according to claims 2 and 4 of the present invention. In FIG. 5, the infrared ray 42 carrying the data arrived from the optical communication device (not shown) on the transmitting side is received by the receiving section 44 of the optical communication device 43 on the receiving side for optical communication.

In this case, the sunlight 45, the illumination light 46 and the like as ambient light are simultaneously incident on the receiver 44. here,
In this embodiment, an irradiation position changing device 49 is provided in front of the plurality of light receivers 47 so as to change the irradiation position to the plurality of light receivers 47 in accordance with the direction of incident light. Further, an attenuator 48 for attenuating the output of each of these light receivers 47 is provided, and the threshold value of the light intensity at which the attenuation factor of the attenuator 48 changes greatly is set to the light intensity at which the noise due to light has a great influence. Or infrared 4 for optical communication
2 is set so that the frequency range of intensity modulation mainly occurs in the frequency range of intensity change of ambient light, or the optical communication is performed at an optical wavelength at which the intensity of ambient light does not have a great adverse effect on the infrared ray 42 for optical communication. The light wavelength of the infrared ray 42 for use is set, or a combination thereof is set.

As a result, in the light receivers 47 and the like existing at the positions 410 and 411 irradiated by the ambient light such as the sunlight 45 and the illumination light 46, the ambient light such as the sunlight 45 and the illumination light 46 is provided by the attenuator 48. The output generated by the above can be attenuated and its influence can be suppressed. Therefore, it is possible to suppress noise that has been a hindrance to data reception until now, and it is possible to speed up optical communication. Here, as the attenuator 48 for attenuating the output of the light receiver 47, it is well known that there are many circuits including a switch circuit and a grip circuit.

FIG. 6 is a schematic view of the essential parts of a light receiving device in an optical communication device according to a fifth aspect of the present invention. Of FIG.
By arranging the lens 5a1 and the irradiation target 5a2 as shown in (a), it is possible to configure a device that spatially converts the direction of incident light into an arbitrary position. For example, light incident from the direction 5a3 and the direction 5a4 is reflected by the lens 5a1.
By this action, the irradiation target 5a2 is irradiated at different positions such as 5a5 and 5a6.

It is a well known fact that a plano-convex lens, an aspherical lens or a combination lens is used as the monospherical lens in order to suppress the aberration, and the object to be irradiated is irradiated along the spherical aberration. Obviously, it may be curved or the lens and the irradiation target may be inclined.

The device for converting the incident light irradiation position is
As shown in FIG. 6 (b), it can also be configured by disposing the pinhole 5b1 and the irradiation target 5a2. For example, the light incident from the direction 5b3 and the direction 5b4 is irradiated on the irradiation target 5b2 at the positions of 5b5 and 5b6 by the action of the pinhole 5b1.

FIG. 7 is a block diagram showing the essential parts of a transmittance varying device in an optical communication device according to claim 6 of the present invention. As shown in (a) of FIG. 7, the transmittance varying device 6a1 in which the transmittance of light changes according to the light intensity is a photochromic substance 6a.
It is composed of a permeable substance 6a3 containing 2. Further, as shown in FIG. 7B, it can be constituted by a transmissive substance 6b3 containing a photochromic substance 6b2 and a reflection plate 6b4.

FIG. 7 shows the photochromic substances 6a2 and 6a.
Although b2 is shown as dispersedly contained, it is obvious that it may be contained in layers or meshes. Examples of such photochromic substances 6a2 and 6b2 include inorganic compounds such as Hg ₃ S ₂ I ₂ and ZnS,
Various hydrazones, osazones, fulgides, stilbenes,
Salicylaldehyde, spiropyran, biimidazolyl,
It is well known that there are organic compounds such as biantron.

Further, the transmissive substances 6a3, 6 which transmit light
It is well known that there are many substances such as various glasses and plastics as b3, and many substances such as mirrors and metal plates as the reflection plate 6b4, which can be used.

Here, since the change in the light intensity of ambient light is much gentler than that of infrared light for optical communication even when the movement of the optical communication device is taken into consideration, the photochromic substance 6 is used.
The suppression effect can be further improved by selecting a2, 6b2 and the like so as to react only to the change in the light intensity caused by the ambient light and the like and not to the change in the infrared ray for optical communication.

FIG. 8 is a block diagram of a main part of a light receiving device in an optical communication device according to claim 7 of the present invention. Variable device 71 whose light transmittance or reflectance changes according to light intensity
Is a conversion device 72 for converting light intensity into voltage or current;
The voltage or current output from the converter 72 is input via a conductor 73, and the voltage or current is used to change the transmittance or reflectance.

It is well known that the converter 72 for changing the light intensity into a voltage or a current can be realized by many means such as PD (photodiode), APD (avalanche photodiode), or PCD (photoconductive device). .

It is well known that the device 73 capable of changing the light transmittance or the reflectance by voltage or current can be realized by various means such as various liquid crystal displays used for liquid crystal display.

FIG. 9 is a block diagram showing an arrangement example in the case of providing a light shielding device 81 for shielding light having a wavelength other than a carrier wave used for optical communication in order to suppress noise. For example, if the variable device 82 whose transmittance or reflectance changes depending on the light intensity operates sufficiently even at the wavelength of the carrier wave of optical communication, (b) in FIG.
As shown in FIG. 6, there are various cases in which a light shielding device 81 that shields light having a wavelength other than the carrier wave used for optical communication is placed on the incident light 84 side from a variable device 82 whose transmittance or reflectance changes depending on the light intensity. It's easy to see.

On the other hand, in the case where it has a weak sensitivity to infrared rays, in order to operate with visible light, (a) in FIG.
As shown in, it is necessary to insert a light shielding device 81 that shields light having a wavelength other than the carrier wave used for optical communication from the variable device 82 whose transmittance or reflectance changes depending on the light intensity on the side of the light receiver 83. Here, it is well known that there are many devices such as various absorption filters and dichroic filters as the light shielding device 81 that shields light having a wavelength other than the carrier wave used for optical communication.

[0067]

As described above, according to the first aspect of the present invention, the receiving sensitivity varying means changes the receiving sensitivity according to the incident direction of light, and the ambient light other than the signal light is incident from an unnecessary direction. Since it is possible to weaken the reception sensitivity of the, it is possible to suppress the irradiation of the ambient light to the light receiver, it is possible to suppress the noise that had been disturbing reception until now due to the effect of this ambient light,
It has an advantage that data can be received with high reliability even under the condition of low light receiving power and high ambient light, and high-speed optical communication can be performed.

According to claim 2, in addition to the above effect, the irradiation position of the light to the receiving unit is converted into a predetermined position,
Since the irradiation positions of the signal light and the ambient light are different from each other, it is possible to further suppress the irradiation of the light receiver with the ambient light.

According to the third aspect, in addition to the above effects, the light transmittance or reflectance is changed according to the light intensity of the incident light, so that the light intensity is weaker than that of the signal light, for example. If the transmittance or the reflectance is changed by the variable means so as to attenuate the light such as the ambient light, most of the light that passes through the variable means or is reflected by the variable means and enters the light receiver becomes signal light. Since the ambient light other than the signal light is removed, it is possible to further suppress the irradiation of the light receiver with the ambient light.

Further, according to claim 4, in addition to the above effect, since the attenuation rate of the output of each of the plurality of light receivers is changed by the attenuating means, for example, ambient light other than the signal light is incident. If the attenuation of the output of the light receiver is set to a large value, ambient light components other than the signal light are removed, so that it is possible to further suppress the noise that has hitherto prevented reception due to the influence of ambient light. .

According to the fifth aspect, in addition to the above effect, since the irradiation position of the light on the receiving section is converted by the pinhole or the lens, the structure can be simplified.

According to the sixth aspect, in addition to the above effects, the photochromic substance changes the light transmittance or reflectance in accordance with the light intensity of the incident light, so that ambient light or the like brings about it. The effect of suppressing the ambient light can be further improved by selecting such that it responds only to the change in the light intensity and does not respond to the change in the signal light for optical communication.

Further, according to claim 7, in addition to the above effect, since the light transmittance or reflectance is changed according to the light intensity of the incident light, the light intensity is weaker than that of the signal light, for example. If the transmittance or the reflectance is changed by the variable means so as to attenuate the light such as the ambient light, most of the light that passes through the variable means or is reflected by the variable means and enters the light receiver becomes signal light. Since the ambient light other than the signal light is removed, it is possible to further suppress the irradiation of the light receiver with the ambient light.

According to the eighth aspect, in addition to the above effect, the attenuation rate of the output of each of the plurality of light receivers is changed by the switch circuit or the clipping circuit included in the attenuating means. If the amount of attenuation of the output of the receiver that receives ambient light other than light is set to a large value, ambient light components other than the signal light will be removed, and the effect of ambient light has hindered reception until now. Noise can be further suppressed.

According to claim 9, in addition to the above effects, since infrared rays are used as a carrier wave used for communication, the irradiation position can be easily converted by the irradiation position conversion means, and at the same time, the irradiation position can be easily changed. The transmittance or the reflectance can be easily changed by the variable means.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of a light receiving device in an optical communication device according to an embodiment of the present invention.

FIG. 2 is a diagram showing the wavelength dependence of ambient light in one example.

FIG. 3 is a configuration diagram of a main part of a light receiving device in an optical communication device according to an embodiment of the present invention.

FIG. 4 is a configuration diagram of a main part of a light receiving device in an optical communication device according to an embodiment of the present invention.

FIG. 5 is a configuration diagram of a main part of a light receiving device in an optical communication device according to an embodiment of the present invention.

FIG. 6 is a configuration diagram of a main part of a light receiving device in an optical communication device according to an embodiment of the present invention.

FIG. 7 is a configuration diagram of a main part of a transmittance varying device in an optical communication device according to an embodiment of the present invention.

FIG. 8 is a configuration diagram of a main part of a light receiving device in an optical communication device according to an embodiment of the present invention.

FIG. 9 is a main part configuration diagram of a light receiving device in an optical communication device according to an embodiment of the present invention.

FIG. 10 is a configuration diagram showing a conventional optical communication device using infrared rays as a carrier wave.

FIG. 11 is a configuration diagram showing a conventional optical communication device using infrared rays as a carrier wave.

FIG. 12 is a configuration diagram showing a conventional optical communication device using infrared rays as a carrier wave.

[Explanation of symbols]

11 ... Receiving side optical communication device, 12 ... Receiving part, 13 ... Infrared, 14 ... Sunlight, 15 ... Illumination light, 3a2 ... Infrared, 3
a3 ... Receiving side optical communication device, 3a4 ... Receiving unit, 3a5 ...
Sunlight, 3a6 ... Illumination light, 3a7 ... Transmittance variable device, 3
a8 ... Irradiation position varying device, 3b2 ... Infrared ray, 3b4 ... Receiving part, 3b5 ... Sunlight, 3b6 ... Illumination light, 3b7 ... Reflectance varying device, 3b8 ... Irradiation position varying device, 3b11 ... Light receiver, 42 ... Infrared ray, 43 ... Optical communication device on receiving side, 44
... receiver, 45 ... sunlight, 46 ... illumination light, 47 ... light receiver, 48 ... attenuator, 5a1 ... lens, 5a2 ... irradiation target, 5b1 ... pinhole, 5b2 ... irradiation target, 6a1
... Variable transmittance device, 6a2 ... Photochromic material, 6a
3 ... Transparent substance, 6b1 ... Transmittance variable device, 6b2 ... Photochromic substance, 6b3 ... Transparent substance, 6b4 ... Reflector, 71 ... Variable device, 72 ... Conversion device, 81 ... Shading device, 82 ... Variable device, 83 ... Light receiver, 84 ... Incident light, α
1 ... Light emitter, α2 ... Infrared, α3 ... Lens, α4 ... Fiber end, α5 ... Fiber cable, α6 ... Fiber end, α7 ... Infrared, α8 ... Lens, α9 ... Light receiver, β1
... light emitter, β2 ... light receiver, β3 ... lens, β4 ... lens, β5 ... infrared light, γ1 ... infrared light emitting device, γ2 ... infrared light receiving device, γ4 ... infrared light, γ4 ... infrared light, γ5 ... wall and ceiling, etc., γ6 ... Emission divergence angle, γ7 ... Receiving light divergence angle.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H04B 10/02 10/18

Claims (9)

[Claims] 1. An optical communication apparatus for wirelessly transmitting and receiving an optical signal, wherein the receiving section is provided with receiving sensitivity varying means for changing the receiving sensitivity according to the incident direction of light. 2. The optical communication device according to claim 1, further comprising irradiation position conversion means for converting an irradiation position of light to the receiving section into a predetermined position. 3. The optical communication device according to claim 1, wherein the reception sensitivity varying means includes a varying means for varying the transmittance or the reflectance according to the light intensity. 4. The reception sensitivity varying means includes a plurality of light receivers, and an attenuation means for changing the attenuation rate of the output of each of the plurality of light receivers. Alternatively, the optical communication device according to claim 2. 5. The optical communication device according to claim 2, wherein the irradiation position conversion means comprises a pinhole or a lens. 6. The optical communication device according to claim 3, wherein the variable means for changing the transmittance or the reflectance in accordance with the light intensity comprises a photochromic substance. 7. The variable means for changing the transmittance or the reflectance in accordance with the light intensity includes a converter for converting the light intensity into a voltage or a current, and a transmittance of incident light based on the voltage or the current, or The optical communication device according to claim 3, further comprising a variable device that changes a reflectance. 8. The optical communication device according to claim 4, wherein the attenuator that changes the attenuation factors of the outputs of the plurality of light receivers includes a switch circuit or a clip circuit. 9. The optical communication device according to claim 1, wherein infrared rays are used as a carrier wave used for communication.