JP2005033564A - Optical transmitting/receiving unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To satisfy a required parallelism of a transmission/reception optical axis without being influenced by variation in various components. <P>SOLUTION: In an application where the transmission optical axis 18 is aligned with an optical receiver 62 in both vertical direction and horizontal direction, four light receiving elements 21b obtained by dividing the light receiving surface by two light receiving element dividing lines 211b and 212b are employed. A light transmitting unit 10 and a light receiving unit 20 are coupled through a mechanism section 91 rotating independently about regulation rotational axes 911b and 912b which are parallel, respectively, with two light receiving element dividing lines 211b and 212b. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical transmission / reception unit of an optical wireless transmission apparatus, and more particularly to an optical transmission / reception unit of a transmitter that transmits an optical signal to a receiver.

  Conventionally, there is an optical space transmission technique for performing digital data transmission using spatial light. In general, in a bidirectional optical space transmission system to which this is applied, optical transceivers that transmit and receive data are opposed to each other and are used in a 1: 1 or 1: n form. Each optical transceiver constituting this system includes an optical transmission / reception unit composed of an optical transmission means using a semiconductor light emitting element such as a light emitting diode or a laser diode, and an optical reception means using a semiconductor light receiving element such as a photodiode. I have.

  Here, when a sufficient distance between the two optical transceivers constituting one transmission path is desired, or when a high-speed transmission path is desired, it is necessary to increase the optical energy transmitted from the optical transmission means to the space. is there. However, sending high light energy over a wide range often involves sending energy to an unnecessary area where there is no transmission partner, which is very inefficient. Therefore, as a light transmitting means, a method is adopted in which light transmitted from a semiconductor light emitting element is converted into a beam shape by a lens or the like and then transmitted to space. Alternatively, as a light receiving means, there is a method in which light coming from space is efficiently taken into a light receiving element by a lens or the like.

  Further, depending on the form of the system, the optical transmitter / receiver may include an optical transmitter / receiver unit using lenses or the like for both the optical transmitter and the optical receiver. In this case, since both the transmission means and the reception means have a narrow angle range (high directivity), it is necessary to align the optical axes so that the optical axes of both means are directed to the transmission partner in order to secure the transmission path. As a premise at that time, the optical transmission / reception unit is required to have the optical axis of the optical transmission means and the optical axis of the optical reception means oriented in the same direction.

As an example, Patent Document 1 below proposes a specific mechanism for optical axis alignment for an optical transmission / reception apparatus equipped with an optical transmission / reception unit having a light transmission means with a narrow emission angle and a light reception means with a narrow incidence angle. is doing. As shown in FIGS. 8 and 11 of Patent Document 1, a general optical transmission / reception unit has a configuration in which an optical transmission unit and an optical reception unit are arranged in parallel, and all elements constituting both are attached to the same member. It has become. Thereby, both optical axes of transmission and reception can be kept substantially parallel.
Japanese Patent Laid-Open No. 10-276131

  When the optical space transmission system is required to transmit at a higher speed and longer distance, it is necessary to further improve the efficiency of the light energy and to make the transmitted light from the light transmitting means have an extremely narrow emission angle. Further, since the emission angle is narrow, the requirement for the parallelism of both optical axes for transmission and reception becomes severe. However, in the conventional optical transmission / reception unit structure, there is a problem that the fluctuation of the transmission optical axis increases due to the optical variation of the light emitting element and the variation of the holding member shape, and the required parallelism of both the transmission / reception optical axes cannot be satisfied. there were.

  It is an object of the present invention to provide an optical transmission / reception unit that can satisfy the required parallelism of transmission / reception optical axes without being affected by variations in various components.

In order to achieve the above object, the present invention comprises a light transmitting unit and a light receiving unit separately, and the light transmitting unit is rotatably connected to the light receiving unit with the dividing line of the light receiving surface of the light receiving element as a rotation axis. The optical axis of the light emitting element and the light receiving axis of the light receiving element are made parallel.
That is, according to the present invention, an optical transceiver unit of an optical wireless transmission device that transmits an optical signal to a receiver,
An optical transmission unit having a light emitting element for emitting the optical signal;
Light having a light receiving element whose light receiving surface is divided into a horizontal direction and / or a vertical direction, receives light for optical axis adjustment transmitted from the receiver, and aligns the optical axis of the light emitting element with the receiver A receiving unit;
The optical transmission unit is rotatably connected to the optical receiving unit with an axis parallel to the dividing line of the light receiving surface of the light receiving element as a rotation axis, and the optical axis of the light emitting element and the light receiving axis of the light receiving element are made parallel. A coupling mechanism for
An optical transmission / reception unit is provided.

  As described above, according to the present invention, the optical transmission unit and the optical reception unit are configured separately, and the optical transmission unit is rotatably connected to the optical reception unit with the dividing line of the light receiving surface of the light receiving element as the rotation axis. Since the optical axis of the light emitting element and the light receiving axis of the light receiving element are made parallel, the high parallelism of the transmission / reception optical axis can be compensated, so that the directivity of the transmitted light is made extremely high (the emission angle is narrowed). Is possible. As a result, the transmission speed of the transmission system can be improved and the transmission distance can be increased, and the accuracy required for each component such as the lens, element, and holding member can be suppressed, and the component manufacturing cost can be reduced. There is also an effect. Furthermore, since the optical transmission unit is rotated about the axis parallel to the dividing line of the light receiving surface of the light receiving element, the adjustment is facilitated, the adjustment process is simplified, and the adjustment cost is reduced.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing an example of an image of an optical space video transmission system expected to be used with the present invention. In the example of FIG. 1, the video display device 50 displays on the optical receiver 62 installed on the video display device (for example, a high-definition display device such as a plasma display panel (PDP) television) 50. This is an optical spatial video transmission system 5 that transmits digital video signal data by optical wireless, and this optical spatial video transmission system 5 provides an image of a tuner or the like to an optical receiver 62 connected (installed) to the video display device 50. A digital video signal is transmitted by optical wireless from an optical transmission device 61 placed on the control device 51.

  In this optical space video transmission system 5, the optical transmission device 61 transmits digital video data to the optical reception device 62 by transmitting the transmission light 19. In order to transmit data efficiently with limited light energy, the transmission light 19 has a narrow emission angle (high directivity). Here, it is an important transmission condition that the transmission light 19 reliably strikes the optical receiver 62. As described above, the optical space video transmission system 5 that needs to apply the transmission light 19 to the optical receiver 62 is required to have a function of optical axis adjustment (optical axis alignment).

  When the optical space video transmission system 5 of FIG. 1 is used at home, the optical transmission device 61 is expected to be placed on the video control device 51 such as a tuner or on a rack in which it is accommodated. In that case, there is a sufficient possibility that the position where the optical transmission device 61 is placed is moved by cleaning the room normally performed. At this time, the optical axis of the transmission light 19 is deviated, and the transmission light 19 does not hit the optical receiver 62, and data transmission cannot be performed. Therefore, the user must adjust the optical axis each time.

  Therefore, for the purpose of avoiding this situation, the optical transmitter 61 is expected to be equipped with a function for automatically adjusting the optical axis. This function is briefly described. First, the optical receiver 62 transmits the reference signal light 39. One optical transmission device 61 mechanically adjusts the optical axis of the transmission light 19 while detecting the reference signal light 39. When the direction (position) where the signal level at which the reference signal light 39 is detected becomes the optimum value is found and stopped at that position, the transmission light 19 of the optical transmission device 61 strikes the optical reception device 62. Here, the reference signal light 39 transmitted by the optical receiver 62 needs a wide emission angle (low directivity).

  Next, a specific configuration example of an optical space transmission system in which the present invention is expected to be used will be described with reference to FIG. In the example of the optical space transmission system shown in FIG. 2, the optical transmission device 61 receives a signal (for example, a video signal) sent from an external data generation device not described here and performs optical space transmission. The signal processed by the transmission signal processing circuit 14 that performs the above processing is driven by the light-emitting element driver 13 by the light-emitting element driver 13, and the transmission light 19 is transmitted to the space via the light-emitting lens 12.

  The optical receiver 62 has a relatively wide incident angle (low directivity) for receiving the transmission light 19 transmitted by the optical transmitter 61 (for example, a PD, an APD, a condensing lens, etc.). A reception signal processing circuit 43 that performs processing such as reception by 41 and electrical amplification by the light receiving circuit 42, and signal processing for transmission to an external device (for example, an image receiving device) not described here. In addition, the light receiving device 62 has a light transmitting element (for example, an LED or a lens added thereto) 31 having a low directivity, a transmitting circuit 33 that generates a reference signal thereof, and a light emitting element driver 32, and transmits light. A reference signal light 39 is transmitted to the device 61 to indicate its position.

  The optical transmission device 61 has a plurality of light receiving elements 21 (for example, PDs) for receiving the reference signal light 39 from the optical receiving device 62 and receives the reception signals of the respective light receiving elements 21 received via the light receiving lens 22. Processing such as electrical amplification by the circuit 23 is added. For the received signal from each light receiving element 21 processed by the light receiving circuit 23, only a specific received signal is selected by the control from the control unit 70 using the signal select circuit 24, and the received level is detected by the reception level detecting circuit 25. Detect and pass the result to the control unit 70.

  The control unit (for example, MPU, DSP, etc.) 70 receives the light receiving element 21 required by using the signal selection circuit 24 in a timely manner to align the transmission optical axis 18 of the transmission light 19 from the optical transmission device 61 with the optical reception device 62. Is selected, the level of each signal obtained by the reception level detection circuit 25 is compared, the drive controller 80 is controlled, and the pan driver 81 and the tilt driver 82 (for example, a stepping motor) are controlled. The directions of the light emitting element 11 and the light receiving element 21 are adjusted. What is important here is the parallelism between the transmission optical axis 18 of the transmission light 19 and the reception optical axis 28 of the reference signal light 39 in the optical transmission device 61. The importance will be briefly described with reference to FIGS. 3, 4, and 5, and examples of specific structures for achieving the object are shown in FIGS. 6, 7, and 8. FIG.

  First, the basic concept of the optical axis in an optical space transmission system that exchanges optical signals in both directions will be described. FIG. 3 illustrates an ideal communication state in which a pair of optical transmission / reception units 90 face each other. In each optical transmission / reception unit 90, the light emitting element 11 and the light receiving element 21 are arranged so that the transmission optical axis 18 and the reception optical axis 28 are parallel to each other. Here, when one transmission optical axis 18 and the other reception optical axis 28 are on the same straight line, a transmission path is established regardless of the directivity of the transmission light. The same applies to the reverse transmission path. That is, if the transmission optical axis 18 and the reception optical axis 28 can be kept parallel in the optical transmission / reception unit 90, an ideal bidirectional transmission path can be established.

  However, as shown in FIG. 4, in reality, the transmission optical axis 18 and the reception optical axis 28 are not parallel due to variations in optical elements and variations in assembly, and an ideal bidirectional transmission path cannot be secured. Here, the directivity (exit angle) of the transmission light 19 is related. If the emission angle of the transmission light 19 is wide, the transmission light 19 reaches the light receiving element 21 'even if the transmission optical axis 18 is displaced, and a transmission path is secured.

  However, in the system in which the present invention is expected to be used, in order to ensure transmission performance (transmission distance, transmission speed, etc.), it is necessary to make the directivity of transmitted light as high as possible (narrow the emission angle). . In this case, as shown in FIG. 5, when an optical axis shift occurs due to variations in optical elements or assembly, the transmission light 19 does not hit the light receiving element 21 ', and a transmission path cannot be secured.

  Therefore, by separating the optical transmission / reception unit 90 into the optical transmission unit 10 and the optical reception unit 20 as shown in FIG. 6A, even if the optical axis is shifted, the optical transmission unit 10 as shown in FIG. 6B. By adjusting the transmission optical axis 18, the transmission light 19 reaches the light receiving element 21, and a transmission path can be secured.

  Next, the optical axis adjustment mechanism will be described below with reference to FIG. The optical transmission / reception unit 90 includes an optical transmission unit 10, an optical reception unit 20, and a mechanism unit 91 that couples the optical transmission unit 10 and the optical reception unit 20 so that they can rotate 360 °. In the light receiving unit 20, the light receiving element 21 is fixed on a light receiving substrate 26 that extracts information from the light receiving element 21, and the light receiving substrate 26 and the light receiving lens 22 are fixed to a reception holding member 27. At this time, the center of the light receiving lens 22 and the center of the light receiving element 21 are arranged in a straight line. This straight line is the reception optical axis 28.

  Similarly, in the optical transmission unit 10, the light emitting element 11 is fixed on the optical transmission board 16 that drives the light emitting element 11, and the optical transmission board 16 and the light emitting lens 12 are fixed to the transmission holding member 17. At this time, the center of the light emitting lens 12 and the center of the light emitting element 11 are arranged on a straight line, and this straight line becomes the transmission optical axis 18. The mechanism unit 91 is fixed to the transmission holding member 17 and the reception holding member 27 in order to connect the transmission unit 10 to the optical reception unit 20 so as to be able to rotate 360 °, and uses a ball joint as a direction-related mechanism. With the above configuration, the directional relationship between the reception optical axis 28 and the transmission optical axis 18 can be changed by 360 °, and as a result, a parallel relationship between both optical axes can be established.

<First Embodiment>
By the way, in the structure shown in FIG. 7, since the transmission unit 10 can rotate 360 degrees, there are innumerable rotation directions, and the optical axis adjustment operation becomes complicated. Therefore, FIG. 8 shows a configuration corresponding to an application in which only the vertical direction (or horizontal direction) of the transmission optical axis 18 is aligned with the optical receiver 62 as the first embodiment. It is divided into two parts only in the vertical direction (or horizontal direction). That is, when a two-divided light receiving element 21 a having a light receiving surface divided into two by a light receiving element dividing straight line 211 a is used as the light receiving element 21, a mechanism unit that rotates around an adjustment rotation shaft 911 parallel to the light receiving element divided straight line 211 a. 91 is used. According to this configuration, it is only necessary to rotate the transmission optical axis 18 only in the vertical direction (or horizontal direction) so as to be parallel to the reception optical axis 28, so that the optical axis adjustment operation is simplified.

<Second Embodiment>
FIG. 9 shows a configuration corresponding to an application in which the transmission optical axis 18 is aligned in both the vertical direction and the horizontal direction with respect to the optical receiver 62 as the second embodiment. Therefore, the two-divided light receiving element 21a is in the vertical direction. = 2 and horizontal direction = 2. That is, when the quadrant light-receiving element 21b obtained by dividing the light-receiving surface into four by two light-receiving element division lines 211b and 212b orthogonal to each other is used as the light-receiving element 21, the two light-receiving element division lines 211b and 212b are respectively A mechanism unit 91 that rotates independently around the parallel adjusting rotation shafts 911b and 912b is used. According to this configuration, it is only necessary to rotate the transmission optical axis 18 in two directions, the vertical direction and the horizontal direction, so that the transmission optical axis 18 is parallel to the reception optical axis 28, so that the optical axis adjustment operation is simplified.

It is explanatory drawing which shows an example of the image of the optical space video transmission system expected that this invention is used. It is explanatory drawing which shows an example of the specific structure of the optical space transmission system with which this invention is anticipated to be used. It is explanatory drawing which shows the optical axis of the optical space transmission system which concerns on this invention. It is explanatory drawing which shows the optical axis offset of the optical space transmission system which concerns on this invention. It is explanatory drawing which shows the optical axis offset of the optical space transmission system which concerns on this invention. It is explanatory drawing which shows the optical axis adjustment which concerns on this invention. It is explanatory drawing which shows an optical axis adjustment mechanism. It is a block diagram which shows 1st Embodiment of the optical transmission / reception unit which concerns on this invention. It is a block diagram which shows 2nd Embodiment of the optical transmission / reception unit which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 5 Optical space video transmission system 10 Optical transmission unit 11 Light emitting element 12 Light emitting lens 13, 32 Light emitting element driver 14 Transmission signal processing circuit 16 Optical transmission board 17 Transmission holding member 18 Transmission optical axis
DESCRIPTION OF SYMBOLS 19 Transmitting light 20 Optical receiving unit 21, 21 'Light receiving element 21a 2 divided light receiving element 21b 4 divided light receiving element 22 Light receiving lens 23, 42 Light receiving circuit 24 Signal selection circuit 25 Reception level detection circuit 26 Optical receiving board
27 reception holding member 28 reception optical axis 31 optical transmission element 33 transmission circuit 39 reference signal light 41 optical reception element 43 reception signal processing circuit 50 video display device 51 video control device 61 optical transmission device 62 optical reception device 70 control unit 80 drive control Part 81 Pan driving means 82 Tilt driving means 90 Optical transmission / reception unit 91 Mechanism parts 211a, 211b, 212b Light receiving element dividing straight lines 911, 911a, 911b, 912b Adjustment rotating shaft

Claims (1)

An optical transceiver unit of an optical wireless transmission device that transmits an optical signal to a receiver,
An optical transmission unit having a light emitting element for emitting the optical signal;
Light having a light receiving element whose light receiving surface is divided into a horizontal direction and / or a vertical direction, receives light for optical axis adjustment transmitted from the receiver, and aligns the optical axis of the light emitting element with the receiver A receiving unit;
The optical transmission unit is rotatably connected to the optical receiving unit with an axis parallel to the dividing line of the light receiving surface of the light receiving element as a rotation axis, and the optical axis of the light emitting element and the light receiving axis of the light receiving element are made parallel. A coupling mechanism for
Optical transmission / reception unit provided.

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