JP2004312390A - Optical wireless transmission apparatus, optical axis alignment method of optical wireless transmission apparatus, optical wireless communication method, and optical wireless transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical wireless transmission apparatus for transmitting a signal by optical wireless communication that can be downsized, carry out optical axis alignment with high accuracy at a high speed and can be applicable to an outdoor use. <P>SOLUTION: In a light receiving and emitting section 9, a light control element 3 for reflecting part of incident light and transmitting the rest and a reflection optical system 4 capable of controlling a deflection angle of incident light with respect to an optical axis are combined, a light emitting element 1 and a lens 2 for for transmitting the light of a data signal or a pilot light, a lens 5 and a first light receiving element 6 for obtaining a position information signal by the pilot light from an opposite apparatus, and a data reception section 39 for receiving the light of the data signal from the opposite apparatus are arranged, and optical axis alignment between the received light from the opposite apparatus and the transmission light from its own optical wireless transmission apparatus is performed coaxially by controlling the deflection angle of the reflection optical system 4 on the basis of the position information signal obtained from the first light receiving element 6. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical wireless transmission device that performs data transmission by transmitting and receiving light modulated by a data signal or the like, an optical axis adjustment method of the optical wireless transmission device, an optical wireless communication method, and an optical wireless transmission system.
[0002]
[Prior art]
Generally, when transmitting a signal via optical wireless, an LED (light emitting diode) or a laser diode is used as a light emitting element on a transmitting side. Among them, in the device for transmitting a signal by LED, the beam diameter of the LED light having a wide directivity must be converged by a focusing lens. Power is reduced. When the beam diameter is widened in this way, there is a problem that interference occurs when a plurality of devices are used in parallel.
[0003]
In order to solve this, for example, an indoor optical wireless transmission device as shown in FIG. 22 has been proposed. In this optical wireless transmission device, a light emitting unit 23 is provided in one device (master unit 21) separately from a light emitting unit 22 for transmitting a data signal, and a pilot light 23A for optical axis adjustment is transmitted from the light emitting unit 23. In the other optical wireless transmission device (slave unit 24), the optical axis direction is displaced, the light receiving device 24A receives the pilot light 23A, and the optical axis is adjusted based on the light receiving level of the pilot light 23A. It is configured. In this device, the LED light is collimated by a parabolic reflector to narrow the beam diameter. By rotating a light receiving device 24A for transmitting a light beam having a narrow directivity by a stepping motor or the like, the device can be horizontally and vertically oriented. It is embodied in a form in which scanning is performed to search for a point at which the maximum light receiving level is obtained in two-dimensional coordinates (for example, see Patent Document 1).
[0004]
On the other hand, in an outdoor optical wireless transmission device using a laser diode, an optical axis adjustment method using a mirror and a beam splitter is adopted (for example, see Patent Document 2).
[0005]
[Patent Document 1]
Patent No. 3059870
[0006]
[Patent Document 2]
JP-A-6-152541
[0007]
[Problems to be solved by the invention]
In order to perform optical axis adjustment in the indoor optical wireless transmission device described above, it is necessary to simultaneously rotate the light receiving device and the light receiving device including the optical system, and the light emitting device and the light emitting device including the optical system. In order to use it, the device becomes large.
[0008]
Further, in order to perform higher-speed transmission, it is necessary for the receiving side to receive transmission light from the partner device with high efficiency, and the transmission light has an extremely narrow directional angle of several degrees [deg]. Must be a beam. When performing two-way communication, it is necessary to match the optical axis of the light-emitting device and the light-receiving device arranged in the same device, but if the directivity of the transmitted light is very narrow, It has been difficult to perform the optical axis alignment of the arranged light emitting device and light receiving device with high accuracy and high speed.
[0009]
Further, as an optical axis adjustment method for matching the optical axes of transmission and reception, the above-described adjustment method of the outdoor optical wireless transmission device can be considered, but this device is a large-scale device using a large number of optical elements. Therefore, the device becomes large, and since it is used for fine adjustment after adjusting the optical axis to some extent, the searchable range of the partner device is as narrow as several degrees and it can be moved to various places indoors. It is not suitable for a device used as a mobile phone.
[0010]
SUMMARY OF THE INVENTION It is an object of the present invention to reduce the size of an apparatus, to perform optical axis alignment with high accuracy and high speed, and to be suitable for indoor use. , An optical wireless communication method, and an optical wireless transmission system.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is a light emitting element that emits light modulated by a data signal or pilot light for optical axis adjustment, and a light beam that emits light emitted from the light emitting element is almost parallel light. A first optical element, a light control element that reflects a part of the incident light and transmits the rest, and a reflection unit that reflects the incident light and controls the deflection angle of the incident light with respect to the optical axis. An optical system, a second optical element for condensing the pilot light transmitted from the partner device, and a first light receiving element for receiving the pilot light condensed by the second optical element, emitted from the light emitting element The light is shaped into a light beam close to a parallel light by the first optical element, passes through the light control element, is reflected in a predetermined direction by the reflection optical system, is transmitted to the partner device, and is incident from the partner device. The pilot light is A light emitting / receiving unit configured to be reflected by an optical system, a part of the light is reflected by the light control element, and then received by the first light receiving element via the second optical element; A third optical element for condensing the light transmitted from the third optical element, a second light receiving element for receiving the light condensed by the third optical element, and transmitting the light transmitted from the partner device to the third optical element A data receiving unit for condensing light at the second light receiving element and receiving a data signal at the second light receiving element, and a deflection angle control signal for controlling a deflection angle of the reflection optical system based on pilot light received at the second light receiving element And a deflection angle control signal supply unit that controls the driving unit of the reflection optical system based on the deflection angle control signal, and the optical axes of the light emitting and receiving unit and the data receiving unit are substantially parallel to each other. And the light received by the first light receiving element. An optical wireless transmission device, wherein the optical axis of light emitted from the light emitting element and light incident from the partner device are aligned by controlling the deflection angle of the reflection optical system based on the lot light. .
[0012]
The invention according to claim 2 is a light emitting element that emits light modulated by a data signal or pilot light for optical axis adjustment, and a first optical element that shapes light emitted from the light emitting element into a beam light close to parallel light. A light control element that reflects a part of the incident light and transmits the rest, a reflecting optical system that has a driving unit that reflects the incident light and controls a deflection angle of the incident light with respect to the optical axis, and transmitted from a partner device. A second optical element for condensing the collected pilot light, a first light receiving element for receiving the pilot light condensed by the second optical element, and the light emitted from the light emitting element is the first optical element After being shaped into a light beam close to a parallel light, reflected by the light control element, reflected by the reflecting optical system in a predetermined direction and transmitted to the partner device, and the pilot light incident from the partner device is reflected by the reflection device. Reflected by the optical system A light-receiving / emitting unit configured to transmit through the light control element and receive light by the first light-receiving element via the second optical element, and a third optical element that condenses transmission transmitted from the partner device; A second light receiving element for receiving the light condensed by the third optical element; condensing the light transmitted from the partner device by the third optical element to form a data signal by the second light receiving element; Calculating a deflection angle control signal for controlling a deflection angle of the reflection optical system based on the data reception unit for receiving light and the pilot light received by the second light receiving element, and calculating the reflection angle based on the deflection angle control signal; A deflection angle control signal supply unit that controls a driving unit of an optical system, wherein the light receiving and emitting unit and the optical axes of the data receiving unit are arranged so as to be substantially parallel to each other, and the light receiving unit receives the first light receiving element. Based on the pilot light, By controlling the direction angle, an optical wireless transmission apparatus and performing optical axis alignment of the light incident from the light and the counterpart device emitted from the light emitting element.
[0013]
According to a third aspect of the present invention, in the optical wireless transmission device according to the second aspect, a reflection surface of the light control element is smaller than an area of light reflected by the reflection optical system.
[0014]
According to a fourth aspect of the present invention, in the optical wireless transmission device according to any one of the first to third aspects, the first light receiving element is constituted by a multi-divided light receiving element, and the deflection angle control signal supply is provided. A calculating means for calculating a moving direction and a moving amount of the reflection optical system based on a light receiving amount in each divided region of the light receiving element to obtain a deflection angle control signal; and a deflection angle calculated by the calculating means. A driving unit for driving the reflection optical system in a horizontal direction or a vertical direction based on a control signal, and a control unit for performing optical axis alignment of light emitted from the light emitting element and light incident from the partner device. It is characterized by.
[0015]
According to a fifth aspect of the present invention, in the optical wireless transmission apparatus according to any one of the first to fourth aspects, the light emitting and receiving unit and the data receiving unit are integrally disposed on a same substrate. .
[0016]
According to a sixth aspect of the present invention, in the optical axis adjusting method for an optical wireless transmission device according to any one of the first to fifth aspects, light incident from the partner device is received by the first light receiving element. The moving direction and the moving amount of the reflection optical system are calculated based on the amount of light received by each of the light receiving elements constituting the first light receiving element to obtain a deflection angle control signal, and the reflection optical system is calculated based on the deflection angle control signal. The optical axis of light emitted from the light emitting element and light incident from the other device are aligned by driving the driving means of the system in the horizontal direction or the vertical direction.
[0017]
According to a seventh aspect of the present invention, the optical wireless transmission device according to any one of the first to fifth aspects is disposed as opposed to a first and a second optical wireless transmission device at a predetermined interval, and the first and second optical wireless transmission devices are arranged. After performing optical axis alignment by the optical axis adjustment method for an optical wireless transmission apparatus according to claim 6, bidirectional communication is performed using the first and second optical wireless transmission apparatuses. An optical wireless communication method characterized in that:
[0018]
According to an eighth aspect of the present invention, in the optical wireless communication method according to the seventh aspect, the first and second optical wireless transmission apparatuses use the optical axis adjustment method of the optical wireless transmission apparatus according to the sixth aspect. After performing the axis alignment, the transmission light of the first and second optical wireless transmission devices is shifted by a fixed amount, and the respective transmission lights are controlled so as to irradiate each other to the data reception unit of the partner device. An optical wireless communication method characterized by performing two-way communication using first and second optical wireless transmission devices.
[0019]
According to a ninth aspect of the present invention, there is provided an optical wireless transmission system in which the optical wireless transmission devices according to any one of the first to fifth aspects are arranged as first and second optical wireless transmission devices at predetermined intervals. After performing the optical axis alignment of the first and second optical wireless transmission devices by the optical axis adjusting method for the optical wireless transmission device according to claim 6, the first and second optical wireless transmission devices are It is characterized in that two-way communication is performed by using this.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of an optical wireless transmission device, an optical axis adjustment method of the optical wireless transmission device, an optical wireless communication method, and an optical wireless transmission system according to the present invention will be described.
[0021]
In the following description, light modulated by a data signal or pilot light for optical axis adjustment is appropriately referred to as light. Of these, light modulated by the data signal is appropriately referred to as light of the data signal. Further, light transmitted to the partner device is referred to as transmission light, emission light, or emission light, and light received from the partner device is referred to as reception light, incident light, or incident light. Further, emitting these lights is called transmission, and receiving them is called light reception or reception.
[0022]
[Embodiment 1]
First, a configuration of an optical wireless transmission apparatus according to the first embodiment and an indoor optical wireless transmission system combining the present apparatus will be described with reference to FIGS.
[0023]
FIG. 1 is a schematic configuration diagram of the optical wireless transmission device according to the first embodiment.
[0024]
The light receiving / emitting section 9 emits light modulated by a data signal or a pilot light for optical axis adjustment, a lens 2 such as a collimator lens, and reflects a part of incident light and transmits the rest. A light control element 3, a reflecting optical system 4 having a driving unit (not shown) for reflecting the incident light and controlling the deflection angle of the incident and outgoing light with respect to the optical axis, and a pilot light transmitted from a partner device (not shown) having the same configuration. It includes a lens 5 for collecting light, and a first light receiving element 6 such as a photodiode (hereinafter, appropriately referred to as PD) for receiving the pilot light collected by the lens 5.
[0025]
In the light emitting element 1 and the lens 2, the outgoing light emitted from the light emitting element 1 via the lens 2 passes through the light control element 3 (partially reflected, the same applies hereinafter), and is reflected by the reflection optical system 4 and transmitted. Are arranged to be transmitted as. The light emitting element 1 is connected to the data supply unit 7 and the external interface 7A. The lens 5 and the first light receiving element 6 pass through the lens 5 after the light incident from the partner device is reflected by the reflection optical system 4 and reflected (partially transmitted, the same applies hereinafter) by the light control element 3. The first light receiving element 6 is arranged to receive light. The first light receiving element 6 and the reflection optical system 4 are connected to a deflection angle control signal supply unit 8.
[0026]
When the light receiving and emitting unit 9 performs optical axis alignment with a partner device, pilot light for optical axis adjustment is emitted from the light emitting element 1. On the other hand, when bidirectional communication is performed with the partner device, light whose intensity is modulated in accordance with the data signal is emitted from the light emitting element 1 by the data supply unit 7 to which the data signal is supplied from the external interface 7A. You. These lights are shaped into light beams close to parallel light by the lens 2, pass through the light control element 3, are reflected by the reflection optical system 4, and are transmitted as transmission light. In the optical axis alignment, the pilot light transmitted from the partner device is reflected by the reflection optical system 4 and reflected by the light control element 3, then condensed by the lens 5 and received by the first light receiving element 6. You. In the first light receiving element 6, the received pilot light is subjected to optical-electrical conversion, and is output to the deflection angle control signal supply unit 8 as position information of the partner device.
[0027]
The data receiving unit 39 includes a lens 37 that condenses light transmitted from the partner device, and a second light receiving element 36 such as a photodiode that receives the light condensed by the lens 37. The second light receiving element 36 is connected to the reception signal processing unit 38 and the external interface 38A.
[0028]
In the data receiving section 39, when bidirectional communication is performed, light from the partner device is collected by the lens 37 and received by the second light receiving element 36. In the second light receiving element 36, the received transmission light is subjected to optical-electrical conversion, and is supplied to the reception signal processing unit 38 as a data signal.
[0029]
FIG. 2 is a schematic configuration diagram in the case where two optical wireless transmission devices are combined to form an indoor optical wireless transmission system (portions equivalent to those in FIG. 1 are denoted by the same reference numerals). When the transmission light transmitted from the light emitting / receiving unit 9 has a certain degree of directivity and the data receiving unit 39 is arranged near the light emitting / receiving unit 9 as in the present embodiment, the optical axis By performing the alignment, the data receiving unit 39 can also receive the transmission light from the partner device transmitted to the light emitting and receiving unit 9 of the own device, and can also receive the data from the data supply unit 7 of the own device. The signal can be transmitted bidirectionally to the reception signal processing unit 38 of the partner device.
[0030]
Next, with reference to FIG. 3 to FIG. 9, each unit configuring the light emitting / receiving unit 9 and the data receiving unit 39 will be described in more detail.
[0031]
As the light emitting element 1, a laser diode can be used. The laser diode emits a narrow beam of emitted light, and further converts the beam into a nearly parallel beam with the lens 2 so that the emitted light can be irradiated to the light control element 3 and the reflection optical system 4 with high efficiency. The wavelength of the laser is not limited to near-infrared, but may be a long wavelength.
[0032]
In the case where the directivity of the transmission light is narrow, in the structure in which the data receiving unit 39 is installed near the light receiving / emitting unit 9 as shown in FIG. 1, the data receiving unit 39 may not be able to obtain a sufficient amount of received light. . In such a case, the mirror 40 is provided below the reflecting optical system 4 as shown in FIG. 3 without disposing the optical axis of the data receiving section 39 and the optical axis of the light receiving / emitting section 9 to be substantially parallel. The leak light of the light applied to the mirror 40 is reflected by 90 degrees, and is applied to the second light receiving element 36. Thereby, even when the directivity of the transmission light is narrow, the data reception unit 39 can sufficiently receive the transmission light.
[0033]
FIG. 4 is a block diagram illustrating a configuration of the data supply unit 7. The data supply unit 7 includes a signal processing unit 11 that converts a data signal from the external interface 7A into a signal that can be transmitted by light, and a light emission that drives the light emitting element 1 so that the light blinks by the signal processed signal. It comprises a drive unit 10.
[0034]
Considering a LAN as an application of the indoor optical wireless transmission system as shown in FIG. 2, when the signal input from the external interface 7A is 100Base-FX, the signal processing unit 11 in the data supply unit 7 uses the block diagram of FIG. 4B / 5B encoder 101 performs 4B / 5B encoding for clock self-reproduction, data is scrambled by descrambling / scrambler 102, and parallel / serial converter 103 converts parallel data into serial data. The NRZ / NRZI converter 104 (and the PLL 105) performs signal processing of performing NRZ / NRZI conversion so as to obtain a signal having no DC component, and inputs the data signal to the light emission driver 10 as a data signal. .
[0035]
FIG. 6 is a block diagram showing the configuration of the deflection angle control signal supply unit 8. The first light receiving element 6 of the light receiving / emitting unit 9 performs optical-to-electric conversion of the pilot light from the partner device, and sends a position information signal such as the presence or absence of the received light or the amount of received light and the light receiving direction to the deflection angle control signal supply unit 8 Supply. Based on the position information signal obtained from the light emitting / receiving unit 9, the deflection angle control signal supply unit 8 moves the reflecting optical system 4 so as to align its own receiving optical axis with light from the partner device, and It comprises a calculation unit 13 for calculating a movement amount to obtain a deflection angle control signal, and a control unit 12 for driving a driving unit (not shown) of the reflection optical system 4 in a horizontal direction or a vertical direction based on the deflection angle control signal.
[0036]
The reception signal processing unit 38 converts the data signal obtained by the data reception unit 39 into a signal suitable for an application. Considering a LAN as an application of the indoor optical wireless transmission system, when a signal to be output to the external interface 38A is 100Base-FX, the received signal processing unit 38 converts the received signal into an NRZI / FX signal as shown in the block diagram of FIG. The NRZI / NRZ conversion is performed by the NRZ converter 111 (and the PLL 112), the serial data is converted to parallel data by the serial / parallel converter 113, and the signal scrambled by the scramble / descrambler 114 is descrambled. Further, signal processing for decoding the 4B / 5B encoded signal by the 4B / 5B decoder 115 is performed, and the decoded signal is input to the external interface 38A as a data signal. Note that the clock reproduction circuit 116 reproduces the timing interval of the clock included in the data signal.
[0037]
FIG. 8 is a configuration diagram when a piezo actuator is used as a driving unit of the reflection optical system 4. The piezo actuator applies the piezoelectric effect of a piezo element. As shown in FIG. 8A, piezo actuators 19 are provided at four locations on the back side of the reflecting portion 18 of the reflecting optical system 4 (in FIG. 8, the piezo actuators 19 are provided). Two are shown). As shown in FIGS. 8B and 8C, each piezo actuator 19 is extended by a voltage applied to the electrode 20. Therefore, by applying different voltages to the four piezo actuators 19 to deflect the reflecting optical system in three dimensions, the deflection angle with respect to the optical axis can be controlled.
[0038]
The driving means in the present invention is not limited to a piezo actuator, and an actuator which can be controlled by a current or a voltage can be used as appropriate. Further, the reflecting portion 18 of the reflecting optical system 4 may have a curved surface, and the curved surface may be driven to have unevenness to control the deflection angle with respect to the optical axis.
[0039]
As the reflecting portion 18 of the reflecting optical system 4, a mirror generated by depositing Au (gold) on an optical resin can be used. FIG. 9 shows the reflectance spectral characteristics of the Au film. In addition, when a thin film that reflects only a specific wavelength is deposited, it also functions as a filter that cuts off extraneous light components in the received light.
[0040]
As the light control element 3, a non-polarization beam splitter (hereinafter, simply referred to as a beam splitter) can be used. It is also possible to use a beam splitter that passes (reflects) only a specific wavelength, and in that case, it also functions as a filter that cuts off extraneous light components in the received light.
[0041]
Next, an operation in the case where the deflection angle control signal supply unit 8 controls the deflection angle with respect to the optical axis based on the information obtained from the light emitting / receiving unit 9 will be described with reference to FIGS.
[0042]
FIG. 10 is a flowchart illustrating a control procedure of the reflection optical system 4 by the deflection angle control signal supply unit 8. FIG. 11 is an explanatory diagram showing a state in which the light receiving spot of the pilot light received on the first light receiving element 6 configured by the four-divided PD moves stepwise. FIG. 12 is a block diagram showing a configuration for realizing the control procedure of FIG. 10 in the deflection angle control signal supply unit 8.
[0043]
Here, as shown in FIG. 12, a case where the first light receiving element 6 is constituted by photodiodes (PD_A, _B, _C, _D) divided into four and the reflecting optical system 4 can be controlled three-dimensionally. Take an example. Hereinafter, the description will be given with reference to FIGS. 11 and 12 as appropriate according to the flowchart of FIG.
[0044]
The pilot light from the partner device is an optical signal having a certain frequency. In the light receiving / emitting unit 9, each of the PDs (PD_A, B, C, D) of the PD (first light receiving element 6) divided into four is used. The received light amount is subjected to optical-electrical conversion, and sent to the deflection angle control signal supply unit 8 as electric signals (SIG_A, B, C, D) having an amplitude corresponding to the received light amount (step S1). The arithmetic unit 13 in the deflection angle control signal supply unit 8 amplifies each signal amplitude by the amplifiers 21, 22, 23, and 24 (step S2), and the A / D converters 25, 26, 27, and 28 amplify the respective signal amplitudes. Is subjected to A / D conversion to obtain the signal level, that is, the amount of light received by each PD as a DC value (step S3). Subsequently, the microprocessor 29 such as a microcomputer / DSP calculates the difference between the light receiving levels of the PDs facing each other in the horizontal direction (Pan) and the vertical direction (Tilt) (step S4), and sets the light receiving level difference to 0. For this purpose, the moving direction and moving amount of the reflecting optical system 4 are calculated and sent to the control unit 12 (steps S5 → S6, steps S9 → S10). The control unit 12 performs D / A conversion of the given value by D / A converters 30 and 31 and supplies the resultant value to drivers 32 and 33 as deflection angle control signals. The drivers 32 and 33 control the reflection optical system 4 in the horizontal and vertical directions. (Steps S7 → S8, Steps S11 → S12).
[0045]
Next, the movement of the light receiving spot on the four-divided PD will be described with reference to FIG. In the drawing, reference numeral 6A denotes a light receiving spot on the quadrant PD when the pilot light is irradiated.
[0046]
In the step (1) in FIG. 11, first, a difference between the light receiving amounts of the PDs A and B opposing each other in the vertical direction is calculated, and light is emitted in a direction to make the difference 0 (downward in FIG. 11). The reflecting optical system 4 is moved in the vertical direction as described above. Next, in the step (2), a difference between the amounts of received light of the PDs C and D facing each other in the horizontal direction is calculated, and light is emitted in a direction to make the difference 0 (rightward in FIG. 11). Next, the reflecting optical system 4 is moved in the horizontal direction.
[0047]
As described above, in the light receiving / emitting section 9, the transmission light and the reception light can be controlled coaxially by the light control element 3, so that the light transmitted from the partner apparatus having the same configuration as shown in FIG. By matching the receiving optical axis, the transmission light of the present apparatus is irradiated to the partner apparatus. In addition, the other device also performs optical axis alignment in the same manner, and the transmission light from the present device is irradiated, and the optical axes of the light receiving / emitting sections 9 of the two devices coincide.
[0048]
In the present embodiment, an example is shown in which the first light receiving element 6 is constituted by a four-divided PD, but the number of divisions of the first light receiving element 6 may be three, five, eight,... The number of divisions may be further increased. Further, in the present embodiment, an example has been described in which the moving direction and the moving amount of the reflective optical system 4 are calculated so that the difference in the amount of light received by the PD becomes zero, but the moving direction and the moving amount are calculated by another algorithm. The calculation may be performed.
[0049]
In the optical wireless transmission apparatus according to the first embodiment, the deflection angle of the reflection optical system 4 is controlled based on the optical axis adjustment pilot light received by the first light receiving element 6, so that the transmission light and the reception light are controlled. Since the optical axis alignment is configured to be performed coaxially, the number of movable parts and optical elements is reduced as compared with a conventional device in which the light receiving device and the light emitting device are simultaneously rotated, and the size of the device can be reduced. In comparison with a specific conventional device, at least a volume ratio of 1/2 or less is achieved.
[0050]
Further, when the optical axis alignment was performed by the optical axis adjustment method of the optical wireless transmission apparatus according to Embodiment 1, the search accuracy of the indoor optical wireless transmission apparatus using the conventional motor was about 0.2 [deg] and the search accuracy was about 0.2 [deg]. While the speed is about 100 to 300 [rad / sec], the apparatus of the present embodiment has a search accuracy of 0.001 [deg] or less, a search speed of 500 [rad / sec] or more, and high accuracy. In addition, high-speed optical axis alignment is realized. In this way, by adopting a configuration in which the pilot light transmitted from the partner device and the optical axis received by the own device coincide with each other, even when a beam with a narrow directional angle is used for the transmission light as an indoor optical wireless transmission system, Thus, highly accurate two-way communication can be performed.
[0051]
Further, since the searchable range of the partner device is wide, it can be moved to various places for indoor use.
[0052]
FIG. 13 is a schematic configuration diagram illustrating another configuration example of the optical wireless transmission device according to the first embodiment. As shown in FIG. 13, in the data receiving unit 39, when the lens 37 is a wide-directional lens (such as a fisheye lens) or when a wide-directional lens 41 is provided above the lens 37, the transmission light in a wide range Can be received.
[0053]
Next, a case where the transmission light is shifted by a fixed amount after the optical axis adjustment will be described with reference to FIGS.
[0054]
In the first embodiment, when a laser diode is used as the light emitting element 1 and the directivity of the transmission light is narrow, the transmission lights of the two devices are respectively reflected by the reflection optical system 4 of the partner device after the optical axis adjustment by the above control procedure is completed. Therefore, the data receiving unit 39 cannot receive the data signal from the partner device. Therefore, as shown in FIG. 14, after adjusting the optical axis, each device shifts the transmission light by a certain amount (θ) and irradiates the position of the data receiving unit 39 of the partner device, thereby enabling the two-way communication. It becomes possible.
[0055]
FIG. 15 is a flowchart illustrating a control procedure when the transmission light is shifted by a fixed amount after the optical axis adjustment. The deflection angle control signal supply unit 8 adjusts the optical axis according to the control procedure shown in FIG. 10 (step S101), and then drives the reflection optical system 4 to shift the transmission signal by a certain amount. Control is performed so as to irradiate the receiving unit 39, and two-way communication is performed (step S102 → S103). During communication, since the first light receiving element 6 of the light receiving / emitting unit 9 does not receive the transmission light from the partner device, the deflection angle control signal supply unit 8 cannot obtain information for control. Therefore, information on the presence or absence of the received light is supplied from the data receiving unit 39 to the deflection angle control signal supply unit 8. In the deflection angle control signal supply unit 8, when the data reception unit 39 cannot receive the transmission light from the partner device due to the movement of the device or the like, the process returns to the optical axis adjustment routine again according to the control procedure of FIG. 10 ( Step S104 → S101).
[0056]
According to the above-described embodiment, even when the directivity of the transmitted light is narrow, the data receiving unit 39 can always receive the data signal from the partner device, so that more accurate two-way communication can be performed. It becomes possible.
[0057]
[Embodiment 2]
Next, a configuration of the optical wireless transmission apparatus according to the second embodiment will be described with reference to FIGS. In each figure, the same parts as those in FIG. 1 are indicated by the same reference numerals.
[0058]
FIG. 16 is a schematic configuration diagram of the optical wireless transmission device according to the second embodiment. 1 are denoted by the same reference numerals.
[0059]
In the second embodiment, the light-emitting element 1 and the lens 2 and the lens 5 and the first light-receiving element 6 are arranged in reverse to FIG. That is, the light emitting element 1 and the lens 2 are configured such that the emitted light emitted from the light emitting element 1 via the lens 2 is reflected by the light control element 3 and then reflected by the reflection optical system 4 to be transmitted as transmission light. Are located in The lens 5 and the first light receiving element 6 reflect the pilot light incident from the partner device by the reflection optical system 4, pass through the light control element 3, are collected by the lens 5, and received by the first light receiving element 6. It is arranged to be.
[0060]
Even when the arrangement of the light emitting element 1 and the lens 2 and the arrangement of the lens 5 and the first light receiving element 6 in FIG. 1 are interchanged as in the present embodiment, the same effect as in the first embodiment can be obtained. it can.
[0061]
By the way, in order to obtain more light information from the partner device at the time of optical axis adjustment, it is necessary to efficiently irradiate the first light receiving element 6 of the light receiving / emitting section 9 with light. Therefore, in the configuration of the optical wireless transmission device shown in the first embodiment (FIG. 1), the reflection surface of the light control element 3 needs to be equal to or larger than the area of the light reflected by the reflection optical system 4.
[0062]
As another configuration example of the second embodiment, as shown in FIG. 17, the arrangement of the light emitting element 1 and the lens 2 and the arrangement of the lens 5 and the first light receiving element 6 are exchanged, and the reflection surface 3A of the light control element 3 is changed. The light control element 3 smaller in size than that in FIG. 16 is arranged so as to be smaller than the area S of the light reflected by the reflection optical system 4.
[0063]
In the configuration of FIG. 17, since the light irradiated to the first light receiving element 6 is the transmitted light of the light control element 3, the light control element 3 is small, and the reflection surface 3 </ b> A is the area of the light reflected by the reflection optical system 4. Even if it is smaller than S, light that is not irradiated to the light control element 3 is directly irradiated to the first light receiving element 6. For this reason, as shown in FIG. 16, it is possible to obtain a light receiving amount equal to or greater than that when the reflection surface of the light control element 3 is large. When the light emitting element 1 is a laser diode or the like, the directivity of the transmission light is narrow, so that the reflection surface of the light control element 3 may be small.
[0064]
Further, in the present embodiment, by reducing the size of the light control element 3, the reflection optical system 4 can be brought close to the light control element 3 as shown in FIG. The size can be reduced, and the design of the light emitting / receiving unit 9 can be given flexibility.
[0065]
[Embodiment 3]
FIG. 19 is an explanatory diagram illustrating a configuration example of the optical wireless transmission and transmission apparatus according to the third embodiment. By arranging the optical members of the light emitting / receiving unit 9 and the data receiving unit 39 in the first to third embodiments on the same substrate 34, the optical wireless transmission device can be configured as a small module 35. For example, when a module having a size of about 5 mm square to 30 mm square is applied by applying a hologram pickup assembling technique or the like, the module can be incorporated in a device such as a personal computer 42 as shown in FIG.
[0066]
As shown in the present embodiment, when the light emitting / receiving section 9 and the data receiving section 39 are integrally arranged on the same substrate, not only the size of the apparatus can be reduced, but also the cost and the search time can be reduced. The effect of shortening is obtained. In addition, when forming an integrated structure, the current microfabrication technology of ICs and the technology of assembling hologram pickups can be applied, so that high-definition arrangement is possible, and the optical axis adjustment for transmission and reception is further facilitated. It becomes something.
[0067]
[Embodiment 4]
Next, another configuration example of the light control element 3 having a function of reflecting a part of incident light and transmitting the rest will be described.
[0068]
As the light control element 3, other than the beam splitter described in each of the above embodiments, a light control element that transmits light incident on a partial area and reflects light incident on another area can be used.
[0069]
In the first embodiment, when the light emitting element 1 is a laser diode or the like, the directivity of the transmission light is narrow, so that the transmission surface of the light control element 3 may be small. In this case, as shown in FIG. 21A, a light control element 51 is used in which a central portion through which light emitted from the light emitting element 1 passes is a transmission region 52, and the remaining portion (back surface) is a reflection surface 53. be able to. The light control element 51 can be manufactured by depositing a reflective material on a region excluding a central portion of a transmission optical element serving as a base. In the light control element 51, light emitted from the light emitting element 1 passes through the transmission region 52, and light received from the partner device is reflected by the reflection surface 53 and guided to the first light receiving element 6. Note that the transmission region 52 of the light control element 51 may be an opening. In this case, it can be manufactured by removing the central portion of the transmission optical element serving as the base.
[0070]
In the case where the light emitted from the light emitting element 1 is reflected by the light control element 3 as in Embodiment 2, as shown in FIG. It is possible to use a light control element 61 in which a central portion for reflection is a reflection surface 62 and all remaining portions are transmission surfaces 63. The light control element 61 can be manufactured by masking all the remaining portions except the central portion of the transmission optical element serving as a base, and depositing a reflective material on a surface on which a reflective surface is formed. In the light control element 61, the light emitted from the light emitting element 1 is reflected by the reflection surface 62, and the light received from the other device is transmitted through the transmission surface 63 and guided to the first light receiving element 6 via the lens 5. Become.
[0071]
[Embodiment 5]
Next, the laser output in each of the above embodiments will be described.
[0072]
In an optical wireless transmission device, light transmitted from the device is limited by safety standards. For example, in the case of a laser diode, its emission intensity and the like are defined by IEC60825-1 (JISC6802: radiation safety standards for laser products in Japan). This criterion limits the light output from the device. In the optical wireless transmission device described in each of the above embodiments, when the light emitting element 1 is a laser diode, the output from the device is within the criterion. Is sufficiently smaller than the level that can be actually output by the laser diode. Therefore, in the case of the first embodiment, the transmission light is transmitted at a safe output level by changing the transmission / reflection ratio of the light control element 3 and lowering the transmittance and increasing the reflectance. The received light can be focused on the first light receiving element 6 with high efficiency. For example, if the level at which the laser diode can output is 10 times the level of the output that can be transmitted from the device, the transmittance of the light control element 3 is set to 10%, and the reflectance is set to 90%.
[0073]
Further, in the light emitting element 1 shown in each of the above embodiments, the output level can be attenuated, and the transmitted light transmitted through the light control element 3 and reflected by the reflection optical system 4 and transmitted to the outside of the apparatus is safe. By being adjustable so that it is below the level limited by the standard, high-speed two-way communication is possible with a level of strength that is safe for the eyes.
[0074]
In each of the above-described embodiments, the light emitting element 1 is configured to emit pilot light for adjusting the optical axis. However, the pilot light is transmitted to another light emitting element disposed inside or outside the light receiving / emitting unit 9. May be configured to be emitted from. The optical axis of this light emitting element is arranged so as to be coaxial or substantially parallel to the optical axis of the light receiving / emitting section 9. In addition, light of a data signal emitted from the light emitting element 1 can be used as pilot light.
[0075]
【The invention's effect】
As described above, in the present invention, by controlling the deflection angle of the reflection optical system, the optical axis alignment of the transmission light and the reception light can be controlled coaxially. The number of movable parts is smaller than that of a conventional apparatus that rotates, and the apparatus can be downsized. Further, even when a beam having a narrow directional angle is used as the transmission light, high-precision and high-speed optical axis alignment can be performed. Further, since the searchable range of the partner device is wide, it can be moved to various places for indoor use.
[0076]
Therefore, when the optical wireless transmission device, the optical axis adjustment method of the optical wireless transmission device, the optical wireless communication method, and the optical wireless transmission system according to the present invention are applied to an indoor optical wireless transmission system, high-precision two-way communication is performed. It is possible to do.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an optical wireless transmission device according to a first embodiment.
FIG. 2 is a schematic configuration diagram when two optical wireless transmission devices are combined to form an indoor optical wireless transmission system.
FIG. 3 is a schematic configuration diagram in the case where a mirror is provided below the reflecting optical system in the first embodiment.
FIG. 4 is a block diagram illustrating a configuration of a data supply unit.
FIG. 5 is a block diagram illustrating a configuration of a signal processing unit.
FIG. 6 is a block diagram illustrating a configuration of a deflection angle control signal supply unit.
FIG. 7 is a block diagram showing a configuration of a reception signal processing unit.
FIG. 8A is a configuration diagram when a piezo actuator is used as a driving unit of a reflection optical system. (B), (c) is an explanatory view when the piezo actuator is extended.
FIG. 9 is an explanatory diagram showing reflectance spectral characteristics of an Au film.
FIG. 10 is a flowchart showing a control procedure of a reflection optical system by a deflection angle control signal supply unit.
FIG. 11 is an explanatory view showing a state in which a light receiving spot of pilot light received by a light receiving element constituted by a four-divided PD moves stepwise.
FIG. 12 is a block diagram showing a configuration for realizing the control procedure of FIG. 10 in a deflection angle control signal supply unit.
FIG. 13 is a schematic configuration diagram showing another configuration example of the optical wireless transmission device according to the first embodiment.
FIG. 14 is an explanatory diagram in a case where transmission light is shifted by a fixed amount after optical axis adjustment in bidirectional communication.
FIG. 15 is a flowchart showing a control procedure when the transmission light is shifted by a fixed amount after the optical axis adjustment.
FIG. 16 is a schematic configuration diagram of an optical wireless transmission device according to a second embodiment.
FIG. 17 is a schematic configuration diagram when the light control element is reduced in FIG. 16;
FIG. 18 is a schematic configuration diagram when the reflection optical system is brought close to the light control element in FIG.
FIG. 19 is an explanatory diagram showing a configuration example of an optical wireless transmission device according to a third embodiment.
FIG. 20 is an explanatory diagram in the case where the optical wireless transmission device according to the third embodiment is mounted on a personal computer.
FIG. 21 is an explanatory diagram showing another configuration example of the light control element. (A) is an explanatory view in the case where the central portion through which the emitted light is transmitted is a transmission region, and all the remaining portions are reflection surfaces. (B) is an explanatory diagram in the case where the central portion where the emitted light is reflected is a reflection surface, and all the remaining portions are transmission surfaces.
FIG. 22 is a schematic configuration diagram of a conventional indoor optical wireless transmission device.
[Explanation of symbols]
1. Light emitting element
2. Lens (first optical element)
3: Light control element
3. Optical element
3A: Transmission area
4: Reflective optical system
4A: actual reflection area
5 Lens (second optical element)
6 First light receiving element
7 Data supply unit
7A: External interface
8. Deflection angle control signal supply unit
9 Light receiving / emitting section
10. Light emission drive unit
11 ... Signal processing unit
12 ... Control unit
13 arithmetic unit
18 ... Reflection part
19 ... Piezo actuator
20 ... electrode
21 ... Amplifier
21 ... Master unit
22 ... Light emitting unit
23 ... Light emitting means
23A ... pilot light
24 ... slave unit
24A: Light receiving device
25 ... Converter
29 ... Microprocessor
30 ... Converter
32 ... Driver
34 ... Substrate
35 ... Module
36 ... second light receiving element
37 ... Lens (third optical element)
38 received signal processing unit
38A: External interface
39: Data receiving unit
40 ... Mirror
41 ... Lens
42 ... PC
101 ... 4B / 5B encoder
102 ... descrambling / scramble section
103: Parallel / serial converter
104 NRZ / NRZI conversion unit
105, 112 ... PLL
111 ... NRZI / NRZ conversion unit
113 ... Serial / parallel converter
114 ... Scramble / descramble section
115 ... 4B / 5B decoder
116 clock recovery circuit

Claims (9)

A light emitting element that emits light modulated by a data signal or pilot light for optical axis adjustment, a first optical element that shapes light emitted from the light emitting element into a beam light close to parallel light, and a part of incident light. A light control element that reflects and transmits the rest, a reflecting optical system that has a drive unit that reflects incident light and controls a deflection angle of the incident light with respect to the optical axis, and condenses pilot light transmitted from a partner device A first light receiving element for receiving the pilot light condensed by the second optical element, and the light emitted from the light emitting element is a beam light close to a parallel light by the first optical element. Is formed, transmitted through the light control element, reflected by the reflective optical system in a predetermined direction and transmitted to the partner device, the pilot light incident from the partner device is reflected by the reflective optical system, some of Light is the light control element In after being reflected, the light receiving and emitting unit configured to be received by the first light receiving element through said second optical element,
A third optical element that condenses the light transmitted from the partner device, a second light receiving element that receives the light condensed by the third optical element, and transmits the light transmitted from the partner device to the third optical element. A data receiving unit that collects light by three optical elements and receives the data as a data signal by the second light receiving element;
A deflection angle control signal for controlling a deflection angle of the reflection optical system is calculated based on the pilot light received by the second light receiving element, and a driving unit of the reflection optical system is controlled based on the deflection angle control signal. A deflection angle control signal supply unit,
Wherein the optical axes of the light receiving / emitting unit and the data receiving unit are arranged to be substantially parallel to each other, and control the deflection angle of the reflection optical system based on the pilot light received by the first light receiving element. The optical wireless transmission apparatus according to claim 1, wherein optical axes of light emitted from the light emitting element and light incident from the partner device are aligned. A light emitting element that emits light modulated by a data signal or pilot light for optical axis adjustment, a first optical element that shapes light emitted from the light emitting element into a beam light close to parallel light, and a part of incident light. A light control element that reflects and transmits the rest, a reflecting optical system that has a drive unit that reflects incident light and controls a deflection angle of the incident light with respect to the optical axis, and condenses pilot light transmitted from a partner device A first light receiving element for receiving the pilot light condensed by the second optical element, and the light emitted from the light emitting element is a beam light close to a parallel light by the first optical element. After being reflected by the light control element, reflected by the reflection optical system in a predetermined direction and transmitted to the partner device, and the pilot light incident from the partner device is reflected by the reflection optical system, Light control element Filtered, and the light emitting and receiving portion configured to receive at the first light receiving element through said second optical element,
A third optical element for condensing the transmission transmitted from the counterpart device, a second light receiving element for receiving light condensed by the third optical element, and transmitting the light transmitted from the counterpart device to the third optical element; A data receiving unit that collects light by three optical elements and receives the data as a data signal by the second light receiving element;
A deflection angle control signal for controlling a deflection angle of the reflection optical system is calculated based on the pilot light received by the second light receiving element, and a driving unit of the reflection optical system is controlled based on the deflection angle control signal. A deflection angle control signal supply unit,
Wherein the optical axis of the light receiving / emitting section and the optical axis of the data receiving section are arranged substantially parallel to each other, and the deflection angle of the reflection optical system is controlled based on the pilot light received by the first light receiving element. The optical wireless transmission apparatus according to claim 1, wherein optical axes of light emitted from the light emitting element and light incident from the partner device are aligned. The optical wireless transmission device according to claim 2,
The optical wireless transmission device according to claim 1, wherein a reflection surface of the light control element is smaller than an area of light reflected by the reflection optical system. The optical wireless transmission device according to any one of claims 1 to 3,
The first light receiving element is configured by a multi-divided light receiving element,
Calculating means for obtaining a deflection angle control signal by calculating a moving direction and a moving amount of the reflection optical system based on a light receiving amount in each divided region of the light receiving element; The driving means of the reflection optical system is driven in the horizontal direction or the vertical direction based on the deflection angle control signal calculated in the step (a), and the optical axes of the light emitted from the light emitting element and the light incident from the partner device are aligned. Control means;
An optical wireless transmission device comprising: The optical wireless transmission device according to any one of claims 1 to 4,
An optical wireless transmission device, wherein the light emitting / receiving unit and the data receiving unit are integrally disposed on the same substrate. The optical axis adjusting method for an optical wireless transmission device according to claim 1, wherein
Light incident from the partner device is received by the first light receiving element, and the direction and amount of movement of the reflective optical system are calculated based on the amount of light received by each of the light receiving elements constituting the first light receiving element to deflect the light. An angle control signal is obtained, and the driving unit of the reflection optical system is driven in a horizontal direction or a vertical direction based on the deflection angle control signal, so that light emitted from the light emitting element and light incident from the partner device are emitted. An optical axis adjusting method for an optical wireless transmission device, comprising: performing optical axis alignment. The optical wireless transmission device according to any one of claims 1 to 5, wherein the optical wireless transmission device is disposed to face each other at a predetermined interval as first and second optical wireless transmission devices. 7. An optical wireless device, comprising: performing optical axis alignment by the optical axis adjusting method for an optical wireless transmission device according to claim 6, and then performing bidirectional communication using the first and second optical wireless transmission devices. Communication method. The optical wireless communication method according to claim 7,
7. After the optical axis alignment of the first and second optical wireless transmission devices is performed by the optical axis adjustment method of the optical wireless transmission device according to claim 6, transmission of the first and second optical wireless transmission devices is performed. After shifting the light by a fixed amount and controlling the respective transmission lights so as to irradiate the data reception units of the partner apparatuses with each other, the two-way communication is performed using the first and second optical wireless transmission apparatuses. Characteristic optical wireless communication method. An optical wireless transmission system in which the optical wireless transmission devices according to any one of claims 1 to 5 are arranged as first and second optical wireless transmission devices facing each other at predetermined intervals,
The optical axis alignment of the first and second optical wireless transmission devices is performed by the optical axis adjustment method for the optical wireless transmission device according to claim 6, and then the first and second optical wireless transmission devices are used. An optical wireless transmission system for performing two-way communication by using a wireless communication system.

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