Patent Publication Number: US-2004047634-A1

Title: Optical wireless device

Description:
TECHNICAL FIELD  
       [0001] The present invention relates generally to network devices, and more particularly to an optical wireless device for optical wireless communications. The present invention is suitable, for example, for an optical wireless device used to build a Local Area Network (“LAN”) between two spaced buildings.  
       BACKGROUND TECHNOLOGY  
       [0002] Along with recent spread of networks, LANs have been frequently used on the same floor and in the same building, and Wide Area Networks (“WANs”) and Metropolitan Area Networks (“MANs”) have already been proposed for a system that connects networks in different places. However, the WANs and MANs use a dial-up adapter and a public network or need a layout of a leased line, and are therefore expensive due to the communication expense or leased line layout expense. Although the WANs and MANs are inevitable when two different places are distant, a simpler method has been demanded in creating a network between two neighboring buildings.  
       [0003] Accordingly, wireless LANs have conventionally been proposed which achieve wireless communications using light, radio waves, etc. instead of using a wire cable. Among them, a wireless LAN that uses radio waves utilizes, for example, of 2.4 GHz band and has such a fast maximum transmission speed as 11 Mbps, but it has a security disadvantage: In an attempt to use such a wireless LAN to connect a third floor of one building only with a eighth floor of another neighboring building, a communication range covers other floors in these buildings.  
       [0004] The instant inventor addresses a wireless LAN that communicates using an optical beam. The optical wireless communication uses two communication devices, one of which emits light, and the other of which receives the light for communication, and limits the communication range to these communication devices for improved security. The optical wireless communication requires optical axes of these two optical wireless to accord with each other, and these devices located at different heights, as described above, should maintain their optical axes stably at predetermined inclined angles in horizontal and perpendicular directions. No optical wireless devices have conventionally been proposed that may easily and stably adjust and fix their optical axis.  
       DISCLOSURE OF THE INVENTION  
       [0005] Accordingly, it is an exemplified object of the present invention to provide an optical wireless device that may easily and stably adjust and fix its optical axis.  
       [0006] In order to achieve the above object, an optical wireless device includes a communication part for optical communications, and an attachment part for rotatably supporting the communication part and for fixing said communication part at a predetermined angle. According to this optical wireless device, the attachment part may adjust an angle of the communication part to a predetermined angle and fix it, thereby easily and stably adjusting and fixing the optical axis of the communication part for stable optical communications.  
       [0007] The attachment part may include a first angle adjustment part for adjusting the angle of the communication part to the predetermined angle, and a second angle adjustment part for providing a fine adjustment to the angle that has been adjusted by the first angle adjustment part, to the predetermined angle. According to this optical wireless device, the first angle adjustment part provides a rough adjustment to the angle of the communication part, and then the second angle adjustment part provides a fine adjustment to the angle of the communication part, providing the faster adjustment and fixation of the optical axis of the communication part than the adjustment using only one angle adjustment part.  
       [0008] Preferably, the first angle adjustment part includes a first rotary part for adjusting a horizontal angle of the communication part. According to this optical wireless device, the first rotary part adjusts a horizontal angle of the communication part, realizing optical communications using two optical wireless devices at different horizontal positions, e.g., two optical wireless devices located at two obliquely arranged buildings.  
       [0009] Preferably, the first angle adjustment part includes a second rotary part for adjusting a perpendicular angle of the communication part. According to this optical wireless device, the second rotary part adjusts a perpendicular angle of the communication part, realizing optical communications using two optical wireless devices at different perpendicular positions, e.g., two optical wireless devices located on different floors in two facing buildings.  
       [0010] For example, the first angle adjustment part includes a fixing part fixed at a predetermined position, a first rotary part rotatably attached to the fixing part, and a second rotary part that is attached to the first rotary part, and rotatable in a rotary direction orthogonal to the first rotary part, wherein one of the first and second rotary parts includes a pair of first projections aligned in a first direction and a pair of second projections aligned in a second direction perpendicular to the first direction, and wherein the other of the first and second rotary parts includes an arc-shaped groove engageable with one of the first projections and one of the second projections, and the second rotary part is rotatable with respect to the other of the first projections and the other of the second projections. The first angle adjustment part may include, for example, a fixing part fixed at a predetermined position, a first rotary part rotatably attached to the fixing part, and a second rotary part attached to the first rotary part, and rotatable in a rotary direction orthogonal to the first rotary part, wherein one of the first and second rotary parts includes a pair of projections, and the other of the first and second rotary parts includes an arc-shaped groove engageable with one of the projections, and the second rotary part is rotatable with respect to the other of the projections.  
       [0011] Preferably, the attachment part includes a fixing mechanism for fixing the communication part. Such a fixing mechanism includes, for example, a screw, a stepwise adjusting gear, or the like. As a result, it is possible to maintain the predetermined angle and prevent an offset between optical axes, providing stable optical communications. Preferably, the attachment part includes an engagement part for holding a cable connected to the communication part. This optical wireless device may prevent an entanglement, slip off, etc. of the cable. The second angle adjustment part is, for example, a pan head.  
       [0012] Preferably, the communication part includes a first transmitter/receiver part for emitting and receiving light for communications, a second transmitter/receiver part for emitting and receiving light for adjusting an optical axis, and a collimator for receiving light emitted from the second transmitter/receiver part of a communication counterpart. According to this optical wireless device, the light for adjusting the optical axis easily recognizes a positional relationship of mutual optical wireless devices and facilitates the adjustment of the light emission position of the optical wireless device, thereby easily and stably adjusting the optical axis. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0013] 
     [0014] FIG. I is a typical view of a computer network using an optical wireless device of one aspect according to the present invention.  
     [0015]FIG. 2 is a schematic perspective view of the optical wireless device shown in FIG. 1.  
     [0016]FIG. 3 is a block diagram showing a structure of a communication part in the optical wireless device shown in FIG. 2.  
     [0017]FIG. 4 is a schematic perspective view showing an attachment part in the optical wireless device shown in FIG. 2.  
     [0018]FIG. 5 is a schematic perspective view showing a rotary part as part of the attachment part shown in FIG. 4.  
     [0019]FIG. 6 is a schematic perspective view showing a fixing part as part of the rotary part shown in FIG. 5.  
     [0020]FIG. 7 is a schematic perspective view showing a first rotary member as part of the rotary part shown in FIG. 5.  
     [0021]FIG. 8 is an enlarged side view showing a variation of the first rotary member as part of the rotary part shown in FIG. 5.  
     [0022]FIG. 9 is a schematic perspective view showing a second rotary member as part of the rotary part shown in FIG. 5.  
     [0023]FIG. 10 is a schematic side view showing a moving direction of the rotary part in the optical wireless device shown in FIG. 2.  
     [0024]FIG. 11 is a schematic perspective view showing the optical communication device of another embodiment according to the present invention. 
    
    
     BEST MODE FOR IMPLEMENTING THE INVENTION  
     [0025] Referring to accompanying drawings, a description will now be given of an inventive optical wireless device  10  and a network device  1  having the same. Here, FIG. 1( a ) is a schematic sectional view of a computer network  1  built on different floors in two buildings using the optical wireless devices  10 . FIG. 1( b ) is a typical view of such a computer network.  
     [0026] In the instant embodiment, the computer network  1  includes two LANs in two buildings  2  and  3 , and a pair of optical wireless devices  10  connecting these LANs. The LANs of this embodiment includes network devices  6   a  and  6   b , such as a hub, router and a switch, a server  8 , and clients  9   a  and  9   b . In the following description, a numeral without a lowercase generalizes a numeral with a lowercase, such as  6   a . The network devices  6  is connected to the optical wireless device  10 , PC  9 , and server  8 .  
     [0027] Of course, an applicability of the present invention is not limited to a building, but covers a school, an apartment, and other buildings, as well as a WAN and MAN.  
     [0028] The buildings  2  and  3  face each other via windows  2   a  and  3   a . In the instant embodiment, two LANs are provided at different heights or perpendicular positions (e.g., a third floor in the building  2  and an eighth floor in the building  3 ) as well as at different horizontal positions. In other words, buildings  2  and  3  are arranged obliquely. Of course, the present invention is applicable to two LANs at the same perpendicular positions and/or horizontal positions, and thus the windows  2   a  and  3   a  may be level with each other and/or face each other straightforward, not obliquely.  
     [0029] The server  8  and clients  9  are connected to the network devices  6  through an Unshielded Twisted Pair Cable (“UTP”). In this embodiment, the server  8  and  9  are implemented as a personal computer (“PC” hereinafter), but the server  8  and  9  applicable to the present invention include network devices, such as a hub, a switch, a router, another network devices, a repeater, a bridge, a gateway device, a PC, a server, and a wireless interconnecting device (such as a access point of an interconnecting device of a wireless LAN).  
     [0030] The optical wireless devices  10  are wireless LAN terminals for optical communications, arranged at a predetermined angle and orientation so that their optical axes accord with each other, and each include a communication part  100  and an attachment part  200 . Although the optical wireless device  10  is provided on a ceiling of each of the buildings  2  and  3  in FIG. 1, it may be provided on a perpendicular surface, such as a wall and partition, a horizontal surface, such as a rack, and other surfaces, as described later. A description will now be given of the optical wireless device  10  with reference to FIGS.  2 - 10 .  
     [0031] As shown in FIGS. 2 and 3, the communication part  100  executes optical communications and includes a converter part  110 , a transmitter part  120 , a receiver part  130 , a laser pointer  140 , and a collimator  150 . Here, FIG. 2 is a perspective view of the optical wireless device  10 . FIG. 3 is a block diagram of the communication part  100  in the optical wireless device  10 . The communication part  100  is connected to the server  8  and client  9  through the UTP or LAN cable  5  and network devices  6 , and maintains communications between the server  8  and client  9 .  
     [0032] The converter part  110  processes an interface for communications between the server  8  and client  9 , and controls the transmitter part  120 , the receiver part  130 , the laser pointer  140  and the collimator  150 . The converter  110  modulates input signals from the server  8  and client  9 , and adjusts the emitted light along the optical axis  4  to a preset reference value. For example, it measures the emitted light intensity along the optical axis  4 , and compares the measured value with the present reference value. As a result of comparison, when the measured value is larger than the reference value, it adjusts the emitted light intensity of the optical axis  4  to be lower, while when the measured value is smaller than the reference value, it adjusts the emitted light intensity of the optical axis  4  to be higher.  
     [0033] The transmitter part  120  emits light including data to be communicated, along the optical axis  4  based on a modulated signal output from the converter part  110 . The receiver part  130  receives optical axis  4  adjusted and input by an input light adjusting part, and converts into an electronic signal corresponding to the input light intensity. The receiver part  130  may use, for example, a diode.  
     [0034] The laser pointer  140  outputs an optical-axis adjusting laser beam under control of the converter part  110 . This laser pointer  140  is used particularly for alignment between the optical wireless devices  10 . The laser beam output from the laser pointer  140  is approximately collimated light. This laser pointer  140  may emit a laser beam of high directivity. The collimator  150  is located to receive the laser beam emitted from the laser pointer  140 . Since the optical axis  4  is adjusted by confirming that the laser beam is irradiated onto this collimator  150 , the laser beam emitted from the laser pointer  140  is preferably a beam as large as or larger than the collimator  150  provided on a front surface of the communication counterpart apart by about 100 m to 700 m. While the laser beam emitted from the laser pointer  140  is irradiated at least onto the collimator  150 , the laser beam should has such directivity that the laser beam is not irradiated onto the receiver part  130 . The light emitted from the laser pointer  140  may be selectively irradiated onto the collimator  150  provided in a region apart from the receiver part  130  on the front surface of the optical wireless device  10  of the communication counterpart.  
     [0035] The collimator  150  receives light emitted from the laser pointer  140  of the communication counterpart. This collimator  150  is used particularly for alignment between the optical wireless devices  10  in cooperation with the laser pointer  40 . Preferably, the size of the collimator  150  is as the same as or larger than that of the light beam. However, more preferably, it is larger, but slightly, than the light beam for alignment with the communication counterpart apart by about 100 m to 700 m.  
     [0036] The attachment part  200  supports the communication part  100  rotatably and fixes it at a predetermined angle. The attachment part  200  includes, as shown in FIG. 4, a fine adjustment part  210  and a rotary part  250 . Here, FIG. 4 is a perspective view of the attachment part  200  in the optical wireless device  10 . Although the attachment part  200  of this embodiment manually adjusts and fixes an angle of the communication part  100 , the present invention covers the automatic angular adjustment and fixation. Such an angular adjustment obtains through the converter part  110  for feedback control, information of whether the optical axes  4  accord with each other between two communication parts  100 .  
     [0037] The fine adjustment part  210  includes, as shown in FIG. 4, a screw  211 , first and second mobile part  212  and  216 , first and second adjustment thumbscrews  214  and  218 , and a bottom part  219 . The fine adjustment part  210  provides a fine adjustment to an angle that has been roughly adjusted by the rotary part  250 , which will be described later. The fine adjustment part  210  of this embodiment uses a pan head structurally similar to that used for a camera, an astronomical telescope, etc. The adjustment mechanism of the pan head uses, for example, an angle-adjusting gear or gears smaller than that in the rotary part, and may provide a relatively finer angular adjustment than that by the rotary part  250 .  
     [0038] The screw  211  fixes the communication part  100  onto the fine adjustment part  210 . The screw  211  includes a thumbscrew and a screw section (not shown), which perforates a hole  217   a  and a hole (not shown) provided in a bottom surface of the communication part  100 , and fixes the communication part  100 . In fixing the communication part  100  using the screw  211 , the communication part  100  may be slightly inclined in a direction M in FIG. 4.  
     [0039] The first rotary part  212  is rotatably supported by the bottom part  219 , and supports the second rotary part  216  rotatably, the first and second adjustment thumbscrews  214  and  218 . The first rotary part  212  includes an angle adjustment mechanism (not shown), which includes, for example, a gear or gears, and engages with corresponding gears of the first and second adjustment thumbscrews  214 ,  218 , second rotary part  216 , and bottom part  219 . The gear (not shown) in the first rotary part  212  is engaged with gears (not shown) of the first adjustment thumbscrew  218  and bottom part  219 . Of course, the present invention may use a member other than a gear for the angle adjustment mechanism.  
     [0040] The first adjustment thumbscrew  218  rotates, when rotated by a user, a first rotary part  212  in the direction M in FIG. 4. Although the direction M is a horizontal direction in FIG. 4, it is a perpendicular direction when the optical wireless device  10  is attached to the perpendicular surface, such as a wall. In this embodiment, the first adjustment thumbscrew  218  rotates manually, but it may be an automatic angle adjustment mechanism, as described above.  
     [0041] The second mobile part  216  supports the communication part  100  using a fixing screw  201 , and is attached rotatably to the first mobile part  212  in the direction N. The second rotary part  216  includes a support part  217  and a screw hole  217   a , and is connected to the angle adjustment mechanism in the first rotary part  212 . The support part  217  has a shape along the shape of the bottom surface of the communication part  100 . In order to reduce the vibration to the communication part  100 , an elastic member, such as rubber and sponge, is preferably provided. The screw hole  217  is used to engage the screw  211  with the communication part  100 .  
     [0042] The second adjustment thumbscrew  214  rotates, when rotated by a user, the second rotary part  216  in the direction N. Although the direction N is a perpendicular direction in FIG. 4, it is a horizontal direction when the optical wireless device  10  is attached to the perpendicular surface, such as a wall. In this embodiment, the second adjustment thumbscrew  214  rotates manually, but it may be an automatic angle adjustment mechanism, as described above.  
     [0043] The bottom part  219  rotatably supports the first rotary part  212 , and is fixed unrotatably by projection parts  285  on the second rotary part  280  of the rotary part  250 .  
     [0044] The rotary part  250  is a mechanism that serves to roughly adjust the angle of the communication part  100  to a predetermined three-dimensional angle and includes, as shown in FIG. 5, a fixing part  260 , and first and second rotary parts  270  and  280 . Here, FIG. 5 is a perspective view showing the rotary part  250  in the optical wireless device  10 .  
     [0045] The fixing part  260  serves to fix the rotary part  250 , and rotatably supports the first rotary part  270  via the fixing support part  261 . The fixing part  260  is made of metal or plastic. The fixing part  260  includes, as shown in FIG. 6, a fixing support part  261 , a fixing-side restriction part  262 , a step  263 , screw holes  264 , and exemplarily has a disc shape. The disc shape maintains a broad installation area suitable for stabilization. Of course, the shape of the top surface  260   a  of the fixing part  260  is not limited to an approximately circle, but may be an approximately polygon if it stabilizes a fixation. Here, FIG. 6 is a perspective view of the fixing part  260  in the optical wireless device  10 . The fixing part  260  is fixed onto a desired installation plane via screws and other means, so that the bottom surface  260  contacts it. The installation plane is not limited to a horizontal surface, such as a ceiling and floor, but may be a perpendicular surface, such as a wall and a partition.  
     [0046] The fixing support part  261  is provided at a center of the fixing part  160 , engaged with a first connecting hole  271  in the first rotary part  270 , which will be described later, and serves as a fulcrum of a rotary motion of the first rotary part  270 . A surface of the fixing support part  261  is, for example, thread-cut so as to fix the first rotary part  270 , which will be described later, at a predetermined position using a nut (not shown), thereby preventing the communication part  100  from shaking.  
     [0047] The fixing-side restriction part  262  cylindrically projects from the fixing-part top surface  260   a , is engaged with a first rotary adjustment hole  272 , which will be described later, and restricts the rotation of the first rotary part  270 . The fixing support part  261  and fixing-side restriction part  262  may be inserted from the fixing part bottom surface  260   c , for example, using a screw and a through bolt. The instant embodiment requires a height of the screw head to be lower than the step  263 , which will be described later, and prevents the screw head from projecting from the fixing part bottom surface  260   c . The step  263  has a circular shape, and is formed such that the screw head is prevented from the fixing part  260   c  for the fixing support part  261  and fixing-side restriction part  262 , which are, for example, screwed from the fixing part bottom surface  260   c  using screws. Therefore, the step  263  should be made higher than the screw head. There are plural (e.g., three in this embodiment) screw holes  264  in the fixing part  260 . The screw hole  264  is preferably arranged at a desired position to stabilize the fixing part  260  around the fixing support part  261 . This embodiment arranges them like a triangle around the fixing support part  261  to stably fix the fixing part  260 . The number of screw holes  264  is variable as long as the number and arrangement maintain the stable fixation. The screw holes  264  may be eliminated for the fixation at the installation place without using a screw. For example, a magnet is attached to the fixing part  260  for fixation. Of course, both the magnet and screw hole  264  may be provided.  
     [0048] The first rotary part  270  is rotatably supported on the fixing part  260 , and supports the second rotary part  280 , which will be described later, rotatably in the direction N. The first rotary part  270  includes, as shown in FIG. 7, a first connecting hole  271 , a first rotary adjustment hole  272 , a pair of second connecting holes  273 , and a pair of second rotary adjustment holes  274 , and has an exemplary sectionally U-shape. Here, FIG. 7 is a perspective view of a first rotary part  270  in the optical wireless device  10 .  
     [0049] The first connecting hole  271  is engaged with the fixing support part  261 , and rotates around it as a fulcrum in a direction A. The first rotary adjustment hole  272  is engaged with the fixing-side restriction part  262 , and allows the first rotary part  270  to rotate within this hole  272 . When it reaches a desired position, it is fixed, for example, by a nut.  
     [0050] A plurality of convexes  275   a  that may elastically project and retreat as shown in FIG. 8( a ) may be provided in the first rotary adjustment hole  272 . In this case, the convex part  275  becomes engaged with the fixing-side restriction part  262  and fixes its position when the first rotary part  270  reaches the desired position. Here, FIGS.  8 ( a ) and  8 ( b ) are plane views as different variations of the first rotary part  270 . As a result, the communication part  100  may stably communicate since the first rotary part  270  is prevented from moving out of the desired position. Preferably, the size of the convex  275  is determined such that the projection of the convex  275  contacts the fixing-side restriction part  262  but does not prevent its smooth rotary action. In addition, the length A of the first rotary adjustment hole  272  is preferably determined such that various cables (not shown) connected to the communication part  100  are not entangled with the attachment part  200 . Although the variation shown in FIG. 8( a ) integrates the first rotary adjustment hole  272   a  with the convex part  275   a , they may have independent structures. In this case, for a contact with the fixing-side restriction part  262  using an elastic member, such as a spring, it is preferably configured such that it moves outward relative to the first rotary adjustment hole  272  and returns to the initial position when it does not contact the fixing-side restriction part  262 . As shown in FIG. 8( b ), it is possible to provide a gear  276   a  engaged with a rack  276   b  around the fixing-side restriction part  262 , a gear  276   c  engaged with the gear  276   a  around the support part  261 , a gear  276   d  engaged with the gear  276   c , and a rotary shaft of the gear  276   d  with a knob. Thereby, a rotation of the knob would rotate the gear  276   d , then rotates the gears  276   c  and  276   a , and moves the gear  276   a  along the rack  276   b , whereby the restriction part  262  moves long the groove  272 . Of course, these variations may also serve to achieve a fixation at the predetermined angle, as in the instant embodiment.  
     [0051] Referring back to FIGS. 5 and 7, a second support parts  281   a , which will be described later, is inserted into the second connecting hole  273 . A second side restriction parts  282   a  is inserted into the second rotary adjustment hole  274 , which allows the second rotary parts  280  to rotate in the direction N by 90 degrees in this embodiment. When it is adjusted to the desired inclined angle in the direction N, it may be fixed by a nut, for example. A plurality of convex  275  may be provided in the second rotary adjustment hole  274 , as shown in FIG. 8( a ). In this case, the convex part  275  becomes engaged with the second side restriction part  282   a  to fix its position. As a result, the communication part  100  may stably communicate since the second rotary part  280  is prevented from moving out of the desired position.  
     [0052] As shown in FIG. 8( c ), the restriction part  282   a  may be moved stepwise by forming the outline of the second rotary adjustment holes  274  stepwise. Preferably in this case, it is preferable that a spring etc. force and fix the restriction part  282   a  after it has moved to a desired angular position. The second side restriction part  282   b  and second support part  281   b  are provided in the first rotary part  270  similar to the second side restriction part  282   a  and second support part  281   a .  
     [0053] The second rotary part  280  is attached to the first rotary part  270 , and rotates in a rotary direction orthogonal to the first rotary part  270 . It includes, as shown in FIG. 9, second support parts  281   a  and  281   b , second side restriction parts  282   a  and  282   b , a cable fixing part  283 , a screw hole  284 , and a projection part  285 , and has an exemplary sectionally U-shape opening the first rotary part  270 . Here, FIG. 9 is a perspective view showing the second rotary part  280  in the optical wireless device  10 . Such a shape has, when viewed from the top surface  280   c , an approximately rectangle. Such a shape provides the second rotary part  280  with such an extra length a that when the communication part  100  is mounted, a communication cable connected to the rear surface (not shown) of the communication part  100  is prevented from being compressed and bent by a wall (not shown). Thereby, the extra length a of the second rotary part  280  contacts the wall, and prevents the communication cable from contacting the wall. The second rotary part  280  includes the second support part and second side restriction part at the side surface  280   b  (not shown), and they serve as the same functions of the members of the second support parts  281   a  and  281   b , second side restriction parts  282   a  and  282   b . In use, one of the second side restriction parts  282   a  and  282   b  is inserted into the second rotary adjustment hole  274 , as shown in FIGS.  10 ( a ) and  10 ( b ). Here, FIG. 10 is a side view showing a moving direction of the second rotary part  280  in the optical wireless device  10 . Therefore, the second rotary part  280  may be disassembled from the first rotary part  270 .  
     [0054] As shown in FIG. 5, the second support part  281   a  is connected rotatably to the second connecting hole  273 , and serves as a fulcrum for the second rotary member  280 . The second support part  281   a  may be made of a screw, for example, which is, in turn, inserted from the side of the first rotary part  270 . The second side restriction part  282   a  serves to restrict the rotary action of the optical wireless device  10  in the direction N in cooperation with the above second rotary adjustment hole  274 . The second support part  281  a and second side restriction part  282   a  may be shaped like a push button type when connected to the first rotary part  270 . A range in which the second side restriction part  282   a  and second rotary adjustment hole  274  restrict is 90° in a direction Y 1 , as shown in FIG. 10( a ).  
     [0055] As shown in FIG. 5, the second support part  281   b  is connected rotatably to the second connecting hole  273 , and serves as a fulcrum for the second rotary member  280 . The second support part  281   b  may be made of a screw, for example, which is, in turn, inserted from the side of the first rotary part  270 . The second side restriction part  282   a  serves to restrict a rotary action of the optical wireless device  10  in the direction N in cooperation with the above second rotary adjustment hole  274 . The second support part  281   b  may be shaped like a push button type when connected to the first rotary part  270 . A range in which the second side restriction part  282   b  and second rotary adjustment hole  274  restrict is 90° in a direction Y 2 , as shown in FIG. 10( b ).  
     [0056] The cable fixing part  283  includes a pair of approximately circular holes that allow the UTP or LAN cable  5  (not shown) connected to the communication part  100  to be inserted. This cable fixing part  283  is exemplary, and it may be modified such that the plane  283  is cut out, when a cable connection terminal is larger than the cable fixing part  283 , so as to insert the cable into the cutout or fix the cable using an elastic member, such as a clip.  
     [0057] The screw hole  284  is used to fix the fine adjustment part  210 . Such a fixation does not need a screw, but may use a magnet or bonding with adhesive agent instead of using the screw hole. The projection part  285  is used to connect the fine adjustment part  210  at a predetermined position, and provided such that it contacts four corners of the fine adjustment part  210 . The projection part  285  is made of the same shaped material as the second rotary part  280 , but may be formed, for example, by using a shock absorbing member, thereby mitigating the external impact applied to the fine adjustment part  210  and communication part  100  in addition to positioning them.  
     [0058] A description will now be given of a variation of the optical wireless device  10  with reference to FIG. 11. The same element in FIG. 11 as that in FIG. 2 is designated by the same reference numeral. Here, FIG. 11 is a perspective view showing a rotary part  250 A as a variation of the optical wireless device  10 A.  
     [0059] The optical wireless device  10 A includes a fixing part  260 A and a second rotary part  280 A, and achieves similar functions to those in FIG. 2 using an approximately triangle fixing part  260 A, first rotary part  270 A, and second rotary part  280 A. The fixing part  260 A uses a three-point supporting screw holes  264 A, and includes a fixing support part  261 A and fixing restriction part  262 A. Needless to say, these members may achieve similar functions as those in the embodiment in FIG. 2.  
     [0060] The second rotary part  280 A is mounted on the first rotary part  270 A, and rotates in a rotary direction orthogonal to the first rotary part  270 A. This second rotary part  280 A includes a pair of second support parts  281 A, a pair of second side restriction parts  282 A, a screw hole (not shown), and a projection part. Thereby, it may rotate in the direction orthogonal to the first rotary part  270 , and achieve similar functions to those in the embodiment shown in FIG. 2. It has a U shape opening in the same direction as the first rotary part  270 , when viewed from the front surface. Such a U-shape serves to support the fine adjustment part  210 A, and be supported by the first rotary part  270 A. Such a shape shortens the length by the extra length a unlike the embodiment in FIG. 2.  
     [0061] Referring back to FIGS. 1 and 2, a description will now be given of an attachment of the optical wireless device  10 . In an attempt to install two optical wireless devices obliquely on different floors, two optical wireless devices  10   a  and.  10   b  are arranged in preset positions. As the way of arrangement, the fixing part  260  is attached to the desired position by a screw or screws. The first fixing part  270  is attached to the attached fixed part  260  using a screw. In this case, angles are adjusted and then the horizontal angles are fixed such that the optical wireless devices  10   a  and  10   b  face each other. Next, the second rotary part  280  is attached and fixed after a perpendicular angle is adjusted to a desired angle. In this case, the optical wireless device  10   a  irradiates light from the bottom to the top, and thus is attached to the second support part  281   a  and second side restriction part  282   a . On the other hand, the wireless device  10   b  irradiates light from the top to the bottom, and thus is attached to the second support part  281   b  and second side restriction part  282   b . The fine adjustment part  210  and communication part  100  are provided on the second rotary part  280 . Then, the optical wireless devices  10   a  and  10   b  are powered on, and the laser pointer switch  140  is turned on in the optical wireless device  10   a . Then, the laser beam is emitted from the laser pointer  140  in the optical wireless device  10   a  to the optical wireless device  10   b . An operator first adjusts the position of the optical wireless device  10   a  such that the laser beam emitted from the laser pointer  140  is irradiated onto the front surface of the optical wireless device  10   b . The position is adjusted by two-dimensionally moving the optical wireless device  10   a  upward and downward and rightward and leftward. Then, an operator uses the fine adjustment part  210  to adjust the position of the optical wireless device  10   a  again such that the laser beam emitted from the laser pointer  140  enters the collimator  150  provided on the front surface of the optical wireless device  10   b . In this stage, usually, the optical axis  4  of the laser pointer  140  accords with the optical axis  4  of the transmitter part  120  and receiver part  130 , whereby the optical wireless device  10   b  receives the laser beam output from the optical wireless device  10   a . Such an angle adjustment enables the optical wireless devices  10   a  and  10   b  to communicate with each other.  
     [0062] Further, the present invention is not limited to these preferred embodiments, and various variations and modifications may be made without departing the scope of the present invention.  
     INDUSTRIAL APPLICABILITY  
     [0063] The present invention may maintain the radiation position of the received optical axis, thereby avoiding arduous readjustment and providing stable information communications. The variable field angle of the optical wireless device may achieve communications irrespective of the height of the installation place and enlarge the optical wireless communication range. As a result, the easy and stable adjustment and fixation of the optical axis as well as information communications are realized irrespective of the installation position.