JP3757949B2 - Optical wireless transmission device, optical axis adjustment method of optical wireless transmission device, optical wireless communication method, and optical wireless transmission system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical wireless transmission apparatus that transmits and receives light modulated by a data signal or the like, an optical axis adjustment method of the optical wireless transmission apparatus, an optical wireless communication method, and an optical wireless transmission system.
[0002]
[Prior art]
In general, when transmitting a signal via optical radio, an LED (light emitting diode) or a laser diode is used as a light emitting element on the transmission side. Of these, in devices that transmit signals using LEDs, the beam diameter of LED light with a wide directivity must be narrowed by a focusing lens. However, because this diaphragm has a limit, the beam diameter widens when it is transmitted over long distances. Power is reduced. When the beam diameter is increased 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 means 23 is provided in one device (master unit 21) separately from the light emitting unit 22 for data signal transmission, and pilot light 23A for adjusting the optical axis is transmitted from the light emitting means 23. In the other optical wireless transmission device (slave unit 24), the optical axis direction is displaced, the pilot light 23A is received by the light receiving device 24A, and the optical axis is aligned based on the received light level of the pilot light 23A. It is configured. This device collimates the LED light with a parabolic reflector so as to reduce the beam diameter. By rotating a light receiving device 24A that transmits a beam with narrow directivity by a stepping motor or the like, the horizontal and vertical directions are obtained. This is embodied in the form of scanning and searching for a point where the maximum light receiving level is obtained in two-dimensional coordinates (see, for example, 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 employed (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 with the indoor optical wireless transmission device, it is necessary to rotate the light receiving device including the light receiving element and its optical system and the light emitting device including the light emitting element and the optical system at the same time. The device becomes large to be used in.
[0008]
Further, in order to perform higher-speed transmission, it is necessary for the receiving side to receive the transmission light from the partner apparatus with high efficiency, and the transmission light has a very narrow directivity angle of about several degrees [deg]. Must be a beam. When performing two-way communication, it is necessary to match the optical axes of the light emitting device and the light receiving device arranged in the same device, but when the directivity of the transmitted light is very narrow, it is up and down like this device. It was difficult to align the optical axes of the arranged light emitting device and light receiving device with high accuracy and high speed.
[0009]
Furthermore, as an optical axis adjustment method for matching the optical axes of transmission and reception, the 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 is used for fine adjustment after adjusting the optical axis to some extent, so the searchable range of the partner device is as narrow as several degrees, and it can be moved to various indoor locations. Therefore, it is not suitable for the device used.
[0010]
SUMMARY OF THE INVENTION An object of the present invention is to reduce the size of an apparatus and to perform optical axis alignment with high accuracy and at high speed, and is suitable for indoor use, and an optical axis adjustment method for an optical wireless transmission apparatus An optical wireless communication method and an optical wireless transmission system are provided.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 is a light emitting element that emits light modulated by a data signal or pilot light for optical axis adjustment, and light emitted from the light emitting element is a beam light that is close to parallel light. A first optical element to be molded, a light control element that reflects part of the incident light and transmits the remainder, and a reflection means that reflects the incident light and has a driving means for controlling the deflection angle of the incident light with respect to the optical axis An optical system, a second optical element that condenses pilot light transmitted from the counterpart device, and a first light receiving element that receives pilot light condensed by the second optical element, and is emitted from the light emitting element Light is shaped into beam light close to 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 counterpart device, and is incident from the counterpart device. The pilot light is A light receiving / emitting unit configured to be reflected by an optical system and reflected by the light control element and then received by the first light receiving element through the second optical element; and the counterpart device A third optical element for condensing the light transmitted from the second optical element and a second light receiving element for receiving the light condensed by the third optical element, and the third optical element for transmitting the light transmitted from the counterpart device And a data receiving unit that receives the light as a data signal by the second light receiving element, and a deflection angle control signal for controlling the deflection angle of the reflection optical system based on the pilot light received by the second light receiving element. And a deflection angle control signal supply unit for controlling the driving means of the reflection optical system based on the deflection angle control signal, and the optical axes of the light emitting / receiving unit and the data receiving unit are substantially parallel to each other. Arranged so that the light received by the first light receiving element is An optical wireless transmission device that performs optical axis alignment of light emitted from the light emitting element and light incident from the counterpart device by controlling a deflection angle of the reflection optical system based on lot light .
[0012]
According to a second aspect of the present invention, there is provided a light emitting element for emitting light modulated by a data signal or pilot light for adjusting an optical axis, and a first optical element for shaping light emitted from the light emitting element into beam light close to parallel light , A light control element that reflects a part of incident light and transmits the rest, a reflection optical system that has a drive means for reflecting the incident light and controlling the deflection angle of the incident light with respect to the optical axis, and transmitting from the counterpart device A second optical element that collects the pilot light that has been collected; a first light receiving element that receives the pilot light that has been collected by the second optical element; and the light emitted from the light emitting element is the first optical element After being shaped into a beam light that is close to parallel light and reflected by the light control element, it is reflected by the reflective optical system in a predetermined direction and transmitted to the counterpart device, and pilot light incident from the counterpart device is reflected by the reflection device. Reflected by the optical system A light receiving / emitting unit configured to pass through the light control element and receive light by the first light receiving element through the second optical element, and a third optical element for collecting the transmission transmitted from the counterpart device, A second light receiving element that receives the light collected by the third optical element; condenses the light transmitted from the counterpart device by the third optical element and generates a data signal by the second light receiving element; A deflection angle control signal for controlling the deflection angle of the reflection optical system is calculated based on the pilot light received by the data receiving unit that receives light and the second light receiving element, and the reflection is performed based on the deflection angle control signal. A deflection angle control signal supply unit for controlling the driving means of the optical system, and is arranged so that the optical axes of the light emitting / receiving unit and the data receiving unit are substantially parallel and received by the first light receiving element. Based on the pilot light, the reflection optical system 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 configured by a multi-divided light receiving element, and the deflection angle control signal supply is provided. A calculating unit that calculates a moving direction and a moving amount of the reflective optical system based on a received light 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 unit. Control means for driving the reflecting optical system driving means in a horizontal direction or a vertical direction based on a control signal to align the optical axes of the light emitted from the light emitting element and the light incident from the counterpart device. It is characterized by.
[0015]
According to a fifth aspect of the present invention, in the optical wireless transmission device according to any one of the first to fourth aspects, the light emitting / receiving unit and the data receiving unit are integrally arranged on the same substrate. .
[0016]
The invention of claim 6 is the optical axis adjustment method for an optical wireless transmission device according to any one of claims 1 to 5, wherein light incident from the counterpart device is received by the first light receiving element, A deflection angle control signal is obtained by calculating a movement direction and a movement amount of the reflection optical system based on the amount of light received by each of the light receiving elements constituting the first light receiving element, and the reflection optics based on the deflection angle control signal. By driving the driving means of the system in the horizontal direction or the vertical direction, the optical axis of the light emitted from the light emitting element and the light incident from the counterpart device is aligned.
[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 a first and a second optical wireless transmission device facing each other at a predetermined interval, and the first and second optical wireless transmission devices are arranged opposite to each other. The optical wireless transmission apparatus according to claim 6, after optical axis alignment is performed by the optical axis adjustment method of the optical wireless transmission apparatus according to claim 6, bidirectional communication is performed using the first and second optical wireless transmission apparatuses. This is an optical wireless communication method.
[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 devices are optically controlled by the optical axis adjustment method of the optical wireless transmission device 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 certain amount, and each transmission light is controlled to irradiate the data receiving unit of the counterpart device, An optical wireless communication method that performs bidirectional communication using first and second optical wireless transmission apparatuses.
[0019]
A ninth aspect of the present invention is an optical wireless transmission system in which the optical wireless transmission device according to any one of the first to fifth aspects is disposed as a first optical wireless transmission device and a second optical wireless transmission device so as to face each other at a predetermined interval. The first and second optical wireless transmission apparatuses are aligned with each other by the optical axis adjustment method of the optical wireless transmission apparatus according to claim 6, and then the first and second optical wireless transmission apparatuses are It is characterized by using it for bidirectional communication.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
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 below.
[0021]
In the following description, light modulated by a data signal or pilot light for optical axis adjustment is appropriately referred to as light. Among these, the light modulated by the data signal is appropriately described as the light of the data signal. Further, light transmitted to the counterpart device is referred to as transmission light, outgoing light, or outgoing light, and light received from the counterpart device is referred to as reception light, incident light, or incident light. Furthermore, emitting these lights is called transmission, and receiving is called light reception or reception.
[0022]
[Embodiment 1]
First, the configuration of the optical wireless transmission apparatus according to the first embodiment and an indoor optical wireless transmission system combining this apparatus will be described with reference to FIGS.
[0023]
FIG. 1 is a schematic configuration diagram of an optical wireless transmission apparatus according to the first embodiment.
[0024]
The light emitting / receiving unit 9 reflects light that is modulated by a data signal or pilot light for adjusting an optical axis, a lens 2 such as a collimator lens, and a part of incident light and transmits the rest. Pilot light transmitted from a light control element 3, a reflection optical system 4 having a drive means (not shown) that reflects incident light and controls a deflection angle of the incident / exit light with respect to the optical axis, and a partner device (not shown) having the same configuration A condensing lens 5 and a first light receiving element 6 such as a photodiode (hereinafter appropriately referred to as PD) for receiving pilot light collected by the lens 5 are provided.
[0025]
In the light emitting element 1 and the lens 2, the emitted light emitted from the light emitting element 1 through the lens 2 is transmitted through the light control element 3 (partly reflected, the same applies hereinafter), reflected by the reflective optical system 4, and transmitted light. Arranged to be transmitted as. The light emitting element 1 is connected to the data supply unit 7 and the external interface 7A. Further, the lens 5 and the first light receiving element 6 are configured such that light incident from the counterpart device is reflected by the reflection optical system 4 and reflected by the light control element 3 (partially transmitted, the same applies hereinafter), and then passes through the lens 5. The first light receiving element 6 is disposed so as 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 / emitting unit 9 performs optical axis alignment with the counterpart device, pilot light for adjusting the optical axis is emitted from the light emitting element 1. On the other hand, when two-way communication is performed with the counterpart device, light that is intensity-modulated according to 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. The These lights are shaped into beam light 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 counterpart 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. The In the first light receiving element 6, the received pilot light is photoelectrically converted and output to the deflection angle control signal supply unit 8 as position information of the counterpart device.
[0027]
The data receiving unit 39 includes a lens 37 that collects light transmitted from the counterpart device, and a second light receiving element 36 such as a photodiode that receives the light collected 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 receiver 39, when performing bidirectional communication, light from the counterpart 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 photoelectrically converted and 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 (the same parts as 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 in the vicinity of the light emitting / receiving unit 9 as in the present embodiment, the optical axis as described above. By performing the matching, the data receiving unit 39 can also receive the transmission light from the counterpart device transmitted toward the light emitting / receiving unit 9 of the own device, and 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 counterpart device.
[0030]
Next, with reference to FIGS. 3 to 9, each part constituting 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 has a narrow beam of emitted light, which is further converted into a nearly parallel beam by 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 the near infrared, but may be a long wavelength.
[0032]
Further, when the directivity of the transmission light is narrow, in the structure in which the data receiving unit 39 is installed in the vicinity of the light emitting / receiving unit 9 as shown in FIG. . In such a case, the optical axis of the data receiving unit 39 and the optical axis of the light emitting / receiving unit 9 are not arranged so as to be substantially parallel, and a mirror 40 is provided below the reflecting optical system 4 as shown in FIG. The configuration is such that the leakage light of the light applied to the mirror 40 is reflected by 90 degrees and 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 showing a configuration of the data supply unit 7. The data supply unit 7 converts the data signal from the external interface 7A into a signal that can be transmitted by light, and 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]
When the LAN is considered as an application of the indoor optical wireless transmission system as shown in FIG. 2 and the signal input from the external interface 7A is 100Base-FX, the signal processing unit 11 in the data supply unit 7 is shown in the block diagram of FIG. As shown in FIG. 4, the 4B / 5B encoder 101 performs 4B / 5B encoding for clock self-regeneration, the descramble / scramble unit 102 scrambles the data, and the parallel / serial converter 103 converts the parallel data into serial data. Then, the signal is processed by the NRZ / NRZI converter 104 (and the PLL 105) to perform NRZ / NRZI conversion in order to obtain a signal having no DC component, and is input to the light emission driver 10 as a data signal. .
[0035]
FIG. 6 is a block diagram showing a configuration of the deflection angle control signal supply unit 8. The first light receiving element 6 of the light receiving / emitting unit 9 photoelectrically converts the pilot light from the counterpart device, and sends position information signals such as the presence / absence of received light, 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 reflection optical system 4 so as to align the optical axis of reception with the light from the counterpart device, and The calculation unit 13 obtains a deflection angle control signal by calculating the amount of movement, and the control unit 12 drives a driving means (not shown) of the reflection optical system 4 in the horizontal direction or the 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 the application. When the LAN is considered as an application of the indoor optical wireless transmission system and the signal output to the external interface 38A is 100Base-FX, the received signal processing unit 38 converts the received signal into the NRZI / RF as shown in the block diagram of FIG. NRZI / NRZ conversion is performed by the NRZ conversion unit 111 (and PLL 112), serial data is converted into parallel data by the serial / parallel conversion unit 113, and then the scrambled signal is descrambled by the scramble / descramble unit 114. Further, the 4B / 5B decoder 115 performs signal processing of decoding the 4B / 5B-encoded signal and inputs the data signal to the external interface 38A as a data signal. Note that the clock recovery circuit 116 recovers the timing interval of the clock included in the data signal.
[0037]
FIG. 8 is a configuration diagram in the case where a piezo actuator is used as a driving unit of the reflection optical system 4. The piezo actuator is an application of 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. Two are shown). Each piezo actuator 19 is expanded by a voltage applied to the electrode 20 as shown in FIGS. Therefore, the deflection angle with respect to the optical axis can be controlled by applying different voltages to the four piezoelectric actuators 19 to deflect the reflection optical system in three dimensions.
[0038]
The driving means in the present invention is not limited to a piezo actuator, and an actuator that can be controlled by current or voltage can be used as appropriate. Further, the reflection unit 18 of the reflection optical system 4 may have a curved surface, and the curved surface is driven to be uneven so that the deflection angle with respect to the optical axis is controlled.
[0039]
As the reflecting portion 18 of the reflecting optical system 4, a mirror generated by vapor-depositing Au (gold) on an optical resin can be used. The reflectance spectral characteristics of the Au film are shown in FIG. In addition, when a thin film that reflects only a specific wavelength is deposited, it also serves as a filter that cuts off extraneous light components in the received light.
[0040]
As the light control element 3, a non-polarizing 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 serves as a filter that cuts off extraneous light components in the received light.
[0041]
Next, with reference to FIGS. 10 to 12, an operation when 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.
[0042]
FIG. 10 is a flowchart showing 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 a light reception spot of pilot light received on the first light receiving element 6 configured by a four-part PD moves in a stepwise manner. 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, the case where the first light receiving element 6 is composed of photodiodes (PD_A, _B, _C, _D) divided into four and the reflection optical system 4 can be controlled three-dimensionally. Take an example. Hereinafter, description will be made with reference to FIGS.
[0044]
The pilot light from the counterpart device is an optical signal having a certain frequency. In the light receiving and emitting unit 9, the PD (PD_A, B, C, D) of each of the four divided PDs (first light receiving elements 6) is obtained. The received light amount is photoelectrically converted and sent to the deflection angle control signal supply unit 8 as an electrical signal (SIG_A, B, C, D) having an amplitude corresponding to the received light amount (step S1). In the calculation unit 13 in the deflection angle control signal supply unit 8, the respective signal amplitudes are amplified by the amplifiers 21, 22, 23, and 24 (Step S 2), and the amplitude values are obtained by the A / D converters 25, 26, 27, and 28. A / D conversion is performed to obtain the signal level, that is, the amount of light received at each PD as a DC value (step S3). Subsequently, the difference in the light reception level between the PDs facing each other in the horizontal direction (Pan) and the vertical direction (Tilt) is calculated by a microprocessor 29 such as a microcomputer / DSP (step S4), and the light reception level difference is set to zero. Therefore, the movement direction and the movement amount of the reflection optical system 4 are calculated and sent to the control unit 12 (step S5 → S6, step S9 → S10). The control unit 12 performs D / A conversion on the given value by the D / A converters 30 and 31 and gives the value to the drivers 32 and 33 as a deflection angle control signal. The drivers 32 and 33 cause the reflective optical system 4 to move in the horizontal and vertical directions. (Step S7 → S8, Step S11 → S12).
[0045]
Next, the movement of the light receiving spot on the quadrant PD will be described with reference to FIG. In the figure, reference numeral 6A denotes a light receiving spot on the quadrant PD when the pilot light is irradiated.
[0046]
In FIG. 11, in step (1), first, the difference between the received light amounts of the PDs A and B facing each other in the vertical direction is calculated, and light is irradiated in the direction in which the difference is zero (downward in FIG. 11). Thus, the reflecting optical system 4 is moved in the vertical direction. Next, in step (2), the difference between the received light amounts of the C and D PDs facing each other in the horizontal direction is calculated, and light is emitted in the direction in which the difference is zero (right direction in FIG. 11). Next, the reflecting optical system 4 is moved in the horizontal direction.
[0047]
In this way, in the light emitting / receiving unit 9, since the transmission light and the reception light can be controlled coaxially by the light control element 3, the light transmitted from the counterpart device having the same configuration as shown in FIG. By matching the optical axis to be received, the transmission light of this apparatus is irradiated to the counterpart apparatus. Similarly, the counterpart device also performs optical axis alignment, and the transmission light from this device is irradiated, so that the optical axes of the light receiving and emitting units 9 of the two devices coincide.
[0048]
In the present embodiment, an example in which the first light receiving element 6 is configured by a four-divided PD is shown, but the number of divisions of the first light receiving element 6 may be three, or five, eight, etc. Further, the number of divisions may be further increased. In the present embodiment, an example in which the movement direction and the movement amount of the reflective optical system 4 are calculated so that the difference in the amount of received light at the PD becomes zero has been described. However, the movement direction and the movement amount are calculated by other algorithms. You may make it calculate.
[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 pilot light for optical axis adjustment received by the first light receiving element 6, so that the transmission light and the reception light are transmitted. Since the optical axis alignment is performed on the same axis, there are fewer movable parts and optical elements than in the conventional device that rotates the light receiving device and the light emitting device at the same time, and the size of the device can be reduced. In comparison with a specific conventional apparatus, at least a volume ratio of 1/2 or less is achieved.
[0050]
Further, when the optical axis alignment is performed by the optical axis adjustment method of the optical wireless transmission apparatus according to the first embodiment, the search accuracy of the indoor optical wireless transmission apparatus using the conventional motor is about 0.2 [deg]. Whereas the speed is about 100 to 300 [rad / sec], in the apparatus according to the present embodiment, the search accuracy is 0.001 [deg] or less and the search speed is 500 [rad / sec] or more. In addition, high-speed optical axis alignment is realized. In this way, by using 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 having a narrow directivity angle is used for the transmitted light as an indoor optical wireless transmission system High-precision bidirectional communication can be performed.
[0051]
Furthermore, since the range in which the counterpart device can be searched is wide, it can be moved to various locations for indoor use.
[0052]
FIG. 13 is a schematic configuration diagram illustrating another configuration example of the optical wireless transmission apparatus according to the first embodiment. As shown in FIG. 13, in the data receiving unit 39, when the lens 37 is of a wide directivity (fisheye lens or the like), or when a wide directivity type lens 41 is provided above the lens 37, the transmitted light in a wide range. Can be received.
[0053]
Next, a case where the transmission light is shifted by a certain amount after the optical axis adjustment will be described with reference to FIGS.
[0054]
In Embodiment 1, when a laser diode is used as the light emitting element 1 and the directivity of the transmitted light is narrow, the transmitted light of the two devices is reflected by the reflecting optical system 4 of the counterpart device after the optical axis adjustment by the control procedure is completed. Therefore, the data receiving unit 39 cannot receive the data signal from the counterpart device. Therefore, as shown in FIG. 14, after adjusting the optical axis, each apparatus shifts the transmission light by a fixed amount (θ) and irradiates the position of the data receiving unit 39 of the counterpart apparatus, thereby enabling bidirectional communication. It becomes possible.
[0055]
FIG. 15 is a flowchart showing a control procedure when the transmission light is shifted by a certain amount after the optical axis adjustment. In the deflection angle control signal supply unit 8, after adjusting the optical axis according to the control procedure of FIG. 10 (step S101), the reflection optical system 4 is driven to shift the transmission signal by a certain amount. Control is performed so as to irradiate the receiver 39, and bidirectional communication is performed (steps S102 → S103). During communication, the first light receiving element 6 of the light emitting / receiving unit 9 does not receive the transmitted light from the counterpart device, so the deflection angle control signal supply unit 8 cannot obtain information for control. Therefore, information on the presence / absence of received light is supplied from the data receiving unit 39 to the deflection angle control signal supplying unit 8. The deflection angle control signal supply unit 8 returns to the routine for adjusting the optical axis according to the control procedure of FIG. 10 again when the transmission light from the counterpart device cannot be received by the data reception unit 39 due to movement of the device or the like ( Step S104 → S101).
[0056]
According to the above embodiment, even when the directivity of the transmission light is narrow, the data reception unit 39 can always receive the data signal from the counterpart device, so that more accurate bidirectional communication can be performed. It becomes possible.
[0057]
[Embodiment 2]
Next, the configuration of the optical wireless transmission apparatus according to the second embodiment will be described with reference to FIGS. In all the drawings, the same parts as those in FIG.
[0058]
FIG. 16 is a schematic configuration diagram of an optical wireless transmission apparatus according to the second embodiment. Parts equivalent to those in FIG. 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 opposite to those in FIG. 1. 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 through the lens 2 is reflected by the light control element 3 and then reflected by the reflection optical system 4 and transmitted as transmission light. Is arranged. The lens 5 and the first light receiving element 6 receive the pilot light incident from the counterpart device by the reflection optical system 4, pass through the light control element 3, collect by the lens 5, and receive the light by the first light receiving element 6. Are 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 is changed 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 information of light from the counterpart device during the optical axis adjustment, it is necessary to efficiently irradiate the first light receiving element 6 of the light receiving and emitting unit 9 with light. Therefore, in the configuration of the optical wireless transmission apparatus shown in Embodiment 1 (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 lens 5 and the first light receiving element 6 is changed, and the reflection surface 3A of the light control element 3 is provided. The light control element 3 having a size smaller than that of 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 transmitted light of the light control element 3, the light control element 3 is small and the reflection surface 3 </ b> A is an area of light reflected by the reflection optical system 4. Even if it is smaller than S, the 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 received light 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 transmitted light is narrow, so 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 closer 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 made flexible.
[0065]
[Embodiment 3]
FIG. 19 is an explanatory diagram of a configuration example of the optical wireless transmission / reception 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 assembly technique or the like, it can be incorporated into a device such as a personal computer 42 as shown in FIG.
[0066]
As shown in the present embodiment, when the light emitting / receiving unit 9 and the data receiving unit 39 are integrally disposed on the same substrate, not only the apparatus can be miniaturized, but also the cost reduction and search time associated therewith are reduced. The effect such as shortening can be obtained. In addition, when using an integrated structure, the current IC microfabrication technology and hologram pickup assembly technology can be applied, enabling high-definition placement and easier adjustment of the transmission and reception optical axes. It will be 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 remaining light will be described.
[0068]
As the light control element 3, other than the beam splitters shown in the above embodiments, a light control element that transmits light incident on a part of the region and reflects light incident on the other region can be used.
[0069]
In the first embodiment, when the light-emitting element 1 is a laser diode or the like, the transmission surface of the light control element 3 may be small because the directivity of transmission light is narrow. In this case, as shown in FIG. 21A, a light control element 51 is used in which the central portion through which light emitted from the light emitting element 1 is transmitted is a transmission region 52 and the remaining portion (back surface) is the reflection surface 53. be able to. The light control element 51 can be manufactured by vapor-depositing a reflective material in a region excluding the central portion of the transmission optical element serving as a base. In the light control element 51, the emitted light from the light emitting element 1 is transmitted through the transmission region 52, and the light received from the counterpart device is reflected by the reflecting surface 53 and guided to the first light receiving element 6. 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 transmissive optical element as a base.
[0070]
Further, when the light emitted from the light emitting element 1 is reflected by the light control element 3 as in the second embodiment, the light emitted from the light emitting element 1 is reflected as shown in FIG. It is possible to use a light control element 61 in which the central portion to be reflected is the reflection surface 62 and the remaining portion is the transmission surface 63. The light control element 61 can be manufactured by masking all the remaining parts except the central part of the transmissive optical element as a base, and depositing a reflective material on the surface on which the 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 counterpart device is transmitted through the transmission surface 63 and guided to the first light receiving element 6 through the lens 5. Become.
[0071]
[Embodiment 5]
Next, 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 radiation intensity is defined by IEC 60825-1 (in Japan, JIS C6802: radiation safety standard for laser products). This reference limits the light output from the device. In the optical wireless transmission device shown in each of the above embodiments, when the light emitting element 1 is a laser diode, the output from the device is within the reference. The laser output of is sufficiently smaller than the level at which the laser diode can actually output. 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, reducing the transmittance, and increasing the reflectance, and The received light can be condensed on the first light receiving element 6 with high efficiency. For example, if the level at which the laser diode can be output is 10 times the level of output that can be transmitted from the apparatus, the transmittance of the light control element 3 is 10% and the reflectance is 90%.
[0073]
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 outside the apparatus is safe. By making it adjustable so that it is below the level limited by the standard, high-speed bi-directional communication is possible at a level that is safe for the eyes.
[0074]
In each of the embodiments described above, the pilot light for adjusting the optical axis is configured to be emitted from the light emitting element 1, but the pilot light is another light emitting element disposed inside or outside the light emitting / receiving unit 9. You may comprise so that it may radiate | emit from. The optical axis of the light emitting element is arranged so as to be coaxial or substantially parallel to the optical axis of the light emitting / receiving unit 9. Further, the light of the 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, the optical axis alignment of the transmission light and the reception light can be controlled coaxially by controlling the deflection angle of the reflection optical system. Compared to the conventional device that rotates, there are fewer movable parts, and the device can be made smaller. Further, even when a beam having a narrow directivity angle is used for the transmission light, it is possible to perform optical axis alignment with high accuracy and high speed. Furthermore, since the range in which the counterpart device can be searched is wide, it can be moved to various locations 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-accuracy bidirectional communication is performed. Can be done.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an optical wireless transmission apparatus 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.
3 is a schematic configuration diagram in the case where a mirror is provided below the reflecting optical system in Embodiment 1. FIG.
FIG. 4 is a block diagram showing a configuration of a data supply unit.
FIG. 5 is a block diagram showing a configuration of a signal processing unit.
FIG. 6 is a block diagram showing a configuration of a deflection angle control signal supply unit.
FIG. 7 is a block diagram showing a configuration of a received signal processing unit.
FIG. 8A is a configuration diagram in the case where a piezo actuator is used as a driving unit of the reflection optical system. (B), (c) is explanatory drawing at the time of extending a piezo actuator.
FIG. 9 is an explanatory diagram showing reflectance spectral characteristics of an Au film.
FIG. 10 is a flowchart showing a control procedure of the reflection optical system by a deflection angle control signal supply unit.
FIG. 11 is an explanatory diagram showing a state in which a light receiving spot of pilot light received by a light receiving element configured by a four-part PD moves in a stepwise manner.
12 is a block diagram showing a configuration for realizing the control procedure of FIG. 10 in the deflection angle control signal supply unit.
13 is a schematic configuration diagram showing another configuration example of the optical wireless transmission apparatus according to the first embodiment. FIG.
FIG. 14 is an explanatory diagram when transmitting light is shifted by a certain amount after optical axis adjustment in bidirectional communication.
FIG. 15 is a flowchart showing a control procedure when transmitting light is shifted by a certain amount after optical axis adjustment;
FIG. 16 is a schematic configuration diagram of an optical wireless transmission apparatus according to the second embodiment.
17 is a schematic configuration diagram when the light control element is reduced in FIG.
FIG. 18 is a schematic configuration diagram when the reflection optical system is brought close to the light control element in FIG. 17;
FIG. 19 is an explanatory diagram showing a configuration example of an optical wireless transmission apparatus according to the third embodiment.
FIG. 20 is an explanatory diagram when the optical wireless transmission apparatus 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 explanatory drawing at the time of making the central part which an emitted light permeate | transmits into a transmissive area | region, and making all the remaining parts into a reflective surface. (B) is explanatory drawing at the time of making the central part which an emitted light reflects into a reflective surface, and making all the remaining parts into a transmissive surface.
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 region
4 ... Reflective optical system
4A ... Real reflection area
5 ... Lens (second optical element)
6 ... 1st light receiving element
7 ... Data supply section
7A ... External interface
8: Deflection angle control signal supply unit
9 ... Light emitting / receiving section
10: Light emission drive unit
11: Signal processor
12 ... Control unit
13. Calculation unit
18 ... Reflecting part
19 ... Piezo actuator
20 ... Electrode
21 ... Amplifier
21 ... Master unit
22 ... Light emitting part
23. Light emitting means
23A ... Pilot light
24 ... handset
24A ... Light receiving device
25 ... Converter
29 ... Microprocessor
30 ... Converter
32 ... Driver
34 ... Board
35 ... Module
36: Second light receiving element
37. Lens (third optical element)
38. Reception signal processing section
38A ... External interface
39: Data receiver
40 ... Mirror
41 ... Lens
42 ... PC
101 ... 4B / 5B encoder
102 ... descrambling / scramble part
103 ... Parallel / serial converter
104 ... NRZ / NRZI converter
105, 112 ... PLL
111... NRZI / NRZ converter
113 ... Serial / parallel converter
114 ... Scramble / descramble part
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 adjusting the optical axis, a first optical element that shapes light emitted from the light emitting element into beam light that is close to parallel light, and a part of incident light A light control element that reflects and transmits the rest, a reflection unit that reflects incident light, and a reflection optical system that has a drive unit for controlling the deflection angle of the reflection unit with respect to the optical axis of the incident light, transmitted from the counterpart device A second optical element for condensing the pilot light and 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 transmitted by the first optical element. Shaped into beam light close to parallel light, transmitted through the light control element, reflected in a predetermined direction by the reflective optical system, transmitted to the counterpart device, and pilot light incident from the counterpart device is transmitted by the reflective optical system. is reflected, the After being reflected by the control device, and a 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 counterpart device, and a second light receiving element that receives the light collected by the third optical element, and transmits the light transmitted from the counterpart device to the first optical element. A data receiving unit that condenses light by three optical elements and receives light as a data signal by the second light receiving element;
A deflection angle control signal for controlling the deflection angle of the reflection optical system is calculated based on the pilot light received by the first light receiving element, and the drive means of the reflection optical system is controlled based on the deflection angle control signal. A deflection angle control signal supply unit,
With
The optical axes of the light receiving / emitting section and the data receiving section are substantially parallel, and the second light receiving element of the data receiving section is the light control element of the light receiving / emitting section and the reflecting section of the reflective optical system. The light transmitted from the counterpart device that is not reflected and passes through the vicinity of the reflective optical system is disposed so as to be collected by the third optical element and received as a data signal by the second light receiving element, The optical axis alignment of the light emitted from the light emitting element and the light incident from the counterpart device is performed by controlling the deflection angle of the reflection optical system based on the pilot light received by the first light receiving element. An optical wireless transmission device. A light emitting element that emits light modulated by a data signal or pilot light for adjusting the optical axis, a first optical element that shapes light emitted from the light emitting element into beam light that is close to parallel light, and a part of incident light A light control element that reflects and transmits the rest, a reflection unit that reflects incident light, and a reflection optical system that has a drive unit for controlling the deflection angle of the reflection unit with respect to the optical axis of the incident light, transmitted from the counterpart device A second optical element for condensing the pilot light and 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 transmitted by the first optical element. is shaped into the beam light close to parallel light, after being reflected by the light control element, the reflection is reflected in a predetermined direction by the optical system is transmitted to the partner apparatus, wherein the reflective optical pilot light incident from the counterpart device Reflected by the system A light receiving and emitting unit that is configured to receive a transmission, and the first light receiving element through said second optical element said light control element,
A third optical element that condenses the light transmitted from the counterpart device, and a second light receiving element that receives the light collected by the third optical element, and transmits the light transmitted from the counterpart device to the first optical element. A data receiving unit that condenses light by three optical elements and receives light as a data signal by the second light receiving element;
A deflection angle control signal for controlling the deflection angle of the reflection optical system is calculated based on the pilot light received by the first light receiving element, and the driving unit of the reflection optical system is controlled based on the deflection angle control signal. A deflection angle control signal supply unit,
With
The optical axes of the light receiving / emitting section and the data receiving section are substantially parallel, and the second light receiving element of the data receiving section is the light control element of the light receiving / emitting section and the reflecting section of the reflective optical system. The light transmitted from the counterpart device that is not reflected and passes through the vicinity of the reflective optical system is disposed so as to be collected by the third optical element and received as a data signal by the second light receiving element, The optical axis alignment of the light emitted from the light emitting element and the light incident from the counterpart device is performed by controlling the deflection angle of the reflection optical system based on the pilot light received by the first light receiving element. An optical wireless transmission device. In the optical wireless transmission device according to claim 2,
An optical wireless transmission apparatus, wherein a reflection surface of the light control element is smaller than an area of light reflected by the reflection optical system. In the optical wireless transmission device according to any one of claims 1 to 3,
The first light receiving element is constituted by a multi-divided light receiving element,
The deflection angle control signal supply unit calculates a movement direction and a movement amount of the reflection optical system based on a light reception amount in each divided region of the light receiving element, and obtains a deflection angle control signal; Based on the deflection angle control signal calculated in step 1, the driving means of the reflection optical system is driven in the horizontal direction or the vertical direction to align the optical axes of the light emitted from the light emitting element and the light incident from the counterpart device. Control means;
An optical wireless transmission device comprising: In the optical wireless transmission device according to any one of claims 1 to 4,
An optical wireless transmission apparatus, wherein the light emitting / receiving unit and the data receiving unit are integrally arranged on the same substrate. In the optical axis adjustment method of the optical wireless transmission device according to any one of claims 1 to 5,
Light incident from the counterpart device is received by the first light receiving element, and deflected by calculating the moving direction and moving amount of the reflective optical system based on the amount of light received by each of the light receiving elements constituting the first light receiving element. An angle control signal is obtained, and 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, so that the light emitted from the light emitting element and the light incident from the counterpart device are An optical axis adjustment method for an optical wireless transmission apparatus, characterized in that optical axis alignment is performed. An optical wireless transmission device that performs optical axis adjustment by the optical axis adjustment method according to claim 6 is disposed as a first and a second optical wireless transmission device facing each other at a predetermined interval, and the first and second optical wireless transmissions are arranged. The apparatus performs two-way communication using the first and second optical wireless transmission apparatuses after performing optical axis alignment by the optical axis adjustment method of the optical wireless transmission apparatus according to claim 6. Optical wireless communication method. In the optical wireless communication method according to claim 7,
7. After the optical axes are aligned by the optical axis adjusting method of the optical wireless transmission apparatus according to claim 6, the first and second optical wireless transmission apparatuses are transmitted by the first and second optical wireless transmission apparatuses. After the light is shifted by a certain amount and controlled so that each transmitted light is irradiated to the data receiving unit of the partner device, bidirectional communication is performed using the first and second optical wireless transmission devices. An optical wireless communication method. An optical wireless transmission system in which an optical wireless transmission device that performs optical axis adjustment by the optical axis adjustment method according to claim 6 is arranged to face each other as a first optical wireless transmission device at a predetermined interval,
The first and second optical wireless transmission apparatuses use the first and second optical wireless transmission apparatuses after optical axis alignment is performed by the optical axis adjustment method of the optical wireless transmission apparatus according to claim 6. An optical wireless transmission system that performs two-way communication.

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