JP4169855B2 - Optical communication device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical communication device incorporated in a device that performs spatial transmission using light.
[0002]
[Prior art]
In general, optical communication devices using a space as a transmission path are roughly classified into those using laser light and those using light emitting diodes (LEDs). Since laser light is extremely strong in directivity, fine adjustment of the light receiving and emitting installation direction is indispensable, making it difficult to use, expensive elements, eye safety issues, etc. Is widely used. An optical signal generated by emitting light from the LED propagates through the space and is received by a light receiving element such as a pin photodiode of the counterpart device. Conversely, an optical signal generated by emitting light from the LED of the counterpart device propagates through the space, is received by the light receiving element of the own device, and is received as a signal.
[0003]
A typical example of the above communication system is the IrDA (Infrared Data Association) system, which is an infrared communication standard, and this system is widely used. Further, as shown in FIG. 10, a technique using an interference unit using a polarizing filter is known in order to prevent light emitted from the self-light-emitting unit from entering the self-light-receiving unit. That is, 4 is a light emitting element, 5 is a light receiving element, and has a structure in which a transmission polarization filter 1 and a reception polarization filter 2 are provided in front of each element 4, 5 (see JP-A-10-126343). ).
[0004]
[Problems to be solved by the invention]
Bidirectional communication paths include full-duplex communication paths and half-duplex communication paths. A full-duplex communication path is desirable because a full-duplex communication path does not require transmission right switching processing and switching time, and transmission processing and reception processing can be performed in parallel. However, in the conventional technique, that is, when LED light emission is used for spatial transmission, only a half-duplex communication path can be provided for the following reason. The reason will be described with reference to FIG.
[0005]
In FIG. 9, when the device 51 communicates with the device 52, the light emitting unit of the device 51 generates an optical signal 53, which is received by the light receiving unit of the device 52, but from the light emitting unit of the device 51. The light signal 53 reaches the light receiving unit of the device 51 itself, and the light receiving intensity is very large because the light emitting unit and the light receiving unit are adjacent to each other. The light emitting unit of the device 51 and the light emitting unit of the device 52 When light is emitted simultaneously, the optical signal from the light emitting unit of the device 51 becomes stronger than the optical signal reaching from the light emitting unit of the device 52, and the reception of the optical signal from the device 52 is obstructed.
[0006]
For this reason, there is an agreement that the communicating devices refrain from light emission when the other party emits light. When a certain moment is captured, only one device can emit light at most. That is, it is impossible to simultaneously transmit an optical signal to the other party and receive an optical signal from the other party in parallel. Therefore, when two-way communication is attempted, a complicated process of performing communication using the ping-pong method while frequently transmitting transmission rights is required.
[0007]
For this reason, when transmitting real-time information, for example, stream information such as audio or video as a signal, there is a time without transmission right, so the information must be temporarily stored, and communication delay occurs, resulting in real-time processing. There was a problem that it would be difficult to use for this.
Further, since the light emitting part and the light receiving part are adjacent to each other, there is a problem that the optical signal from the light emitting part enters the self light receiving part at a considerably high level and saturates the amplifier connected to the receiving part. That is, in FIG. 9, the amplifier cannot receive the optical signal 54 in a state saturated with the optical signal 53, and cannot be ignored because the amplifier once saturated can normally receive the optical signal 54 from the communication partner. Cost. In other words, there is a problem in that it is not possible to receive light immediately after the light emission is completed, but a useless time during which neither light emission nor light reception occurs.
[0008]
As described above, in the currently widely used IrDA communication system, the physical layer is designed as a half-duplex communication path, and the time required for the recovery time from the saturation of the receiving unit as the minimum turnaround time. It is prescribed.
These problems cannot be solved even with the conventional example of FIG. In FIG. 10, the optical signal from the light emitting element 4 may reach the light receiving element 5 directly without passing through the transmission polarizing filter 1. That is, the reflected light 64 in the transmission polarization filter 1, the direct incident light 65, and the light 66 that has passed through the mold 7 are generated. Further, since there is no shielding between the two polarizing filters 1 and 2 orthogonal to each other, light 63 leaks from the transmitting polarizing filter 1 and wraps around the receiving polarizing filter 2 to reach the light receiving element 5. The above problem cannot be solved unless these unnecessary optical signals are removed.
[0009]
Furthermore, in FIG. 11, if a light receiving / emitting element having a light emission polarization direction 71 as a vertical direction and a light reception polarization direction 72 as a horizontal direction is opposed as shown in FIG. Therefore, it is also orthogonal to the polarization direction 72a of the light receiving unit of the counterpart apparatus A01. Alternatively, since the optical signal 75 from the counterpart device has the polarization direction 71a, it is also orthogonal to the polarization direction 72 of the light receiving unit of the own device. As a result, there is a problem that communication becomes impossible.
The present invention has been made in view of such problems, and the object of the present invention is to detect that the light emitted from the device is detected by the light receiving unit of the device by light scattering or reflection. It is an object of the present invention to provide an optical communication apparatus that can prevent and realize a full-duplex communication path at low cost.
[0010]
[Means for Solving the Problems]
The optical communication apparatus of the present invention includes a light emitting element and a light emitting unit having a transmission polarization filter provided in front of the light emitting element, a light receiving element and reception in which the polarization direction is orthogonal to the transmission polarization filter provided in front of the light receiving element. A light receiving unit having a polarizing filter; and an optical blocking member that is provided between the light emitting unit and the light receiving unit and prevents light from the light emitting unit from reaching the light receiving unit.
[0011]
In addition, since the angle between the polarization direction of the transmission polarization filter and the reception polarization filter is more than 30 degrees and less than 60 degrees, the optical signal from the transmission unit of the own device is the same as the polarization direction of the other reception unit. As a result, the polarization direction of the transmission unit of the other party coincides with the polarization direction of the light receiving unit of the own device, and an optical signal can be accurately transmitted in both directions.
The optical blocking member is rotatably attached to the housing, and the light emitting unit and the light receiving unit are integrated with the optical blocking member, so that the positional relationship with the optical communication unit of the counterpart device is shifted. The deviation can be corrected by rotating the light emitting unit and the light receiving unit.
[0012]
A plurality of optical communication apparatuses according to claim 1, wherein the transmission polarization filter and the reception polarization filter have different polarization directions, and a selection unit that switches the polarization direction by selecting one of them, and When the positional relationship is shifted, communication is possible by switching the combination of light receiving and emitting.
A transmission device in which a plurality of light emitting units having a light emitting element and a transmission polarization filter provided in front of the light emitting element are provided separated by an optical blocking member, and the transmission polarization filters of each light emitting unit have orthogonal polarization directions. With this, transmission can be performed through two independent communication paths.
[0013]
A receiving device in which a plurality of light receiving portions each having a light receiving element and a receiving polarization filter provided in front of the light receiving element are provided separated by an optical blocking member, and the polarization directions of the receiving polarizing filters of each light receiving portion are orthogonal to each other. It becomes possible to receive with two independent communication paths.
By including the transmission device and the reception device, transmission and reception can be performed through two independent communication paths in which the polarization directions of light reception and emission of both devices are combined.
[0014]
When a full-duplex mode is selected, comprising switching means for switching between a transmission unit that provides a transmission signal to the light-emitting element and a reception unit that receives a signal from the light-receiving element to select full-duplex or half-duplex mode. Activates one set of light emitting part and light receiving part, and when half duplex is selected, activates two sets of light emitting part and light receiving part at the same time. The two communication paths are independent in direction, and full-duplex communication path and half-duplex communication are possible in spatial light transmission.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a first embodiment of an optical communication apparatus of the present invention. The illustrated optical communication apparatus A is a device incorporated in a housing 6 of a device such as a portable information device, a personal computer, or a printer. A rectangular window 12 is formed on the upper portion of the housing 6, and the optical shielding member 3 is fitted into the window 12. This optical shielding member 3 is a box-shaped member having an upper opening in which two chambers 13 and 14 partitioned by a partition portion 3a at the center are formed. A light emitting element 4 is disposed in the chamber 13 of the optical shielding member 3, and a light receiving element 5 is disposed in the chamber 14. The light emitting element 4 and the light receiving element 5 are provided on the grounding part 8 connected to the substrate 11, respectively, and are connected to the substrate 11 via the terminals 9 and 10. The respective parts of the light emitting element 4 and the light receiving element 5 are integrated by a transparent resin mold 7.
[0016]
The transmission polarizing filter 1 positioned in front of the light emitting element 4 is attached to the opening of the chamber 13, and the light emitting element 17 and the transmission polarizing filter 1 constitute a light emitting unit 17. A receiving polarization filter 2 located in front of the light receiving element 5 is attached to the opening of the chamber 14, and the light receiving element 5 and the receiving polarization filter 2 constitute a light receiving unit 18.
With the above configuration, the light emitting unit 17 including the light emitting element 4 and the transmission polarizing filter 1 and the light receiving unit 18 including the light receiving element 5 and the reception polarizing filter 2 are optically isolated by the optical shielding member 3. ing.
[0017]
As will be described later, the polarization directions of the transmission polarization filter 1 and the reception polarization filter 2 are orthogonal to each other.
When a driving voltage for light emission is applied from the terminal 9, the light emitting element 4 generates an optical signal. Since the light emitting element 4 is isolated by the optical shielding member 3, the signal emitted to the outside is only the signal that has passed through the transmission polarization filter 1. This optical signal tries to return to the light receiving element 5 due to partial scattering or reflection from the other device, but there is a reception polarizing filter 2 on the front surface, and since this polarization direction is orthogonal to the optical signal, it passes through the reception polarizing filter 2. Can not. Therefore, the optical signal from the light emitting element 4 does not reach the light receiving element 5.
[0018]
The devices having the same configuration as the device A described above are opposed and arranged such that the polarization direction of light emission of one device is not orthogonal to the polarization direction of light reception of the other device. The signal from the device can be prevented from being received. With the above mechanism, full-duplex communication can be performed.
In FIG. 1, the light emitting element 4 and the light receiving element 5 are described as physically integrated with the same optical shielding member 3, but the light emitting element 4 and the light receiving element 5 may be configured as separate modules. Good.
[0019]
The optical shielding member 3 only needs to have a shielding effect, and an opaque substance is generally used. However, the optical shielding member 3 has a reflecting means such as aluminum vapor deposition, or a configuration in which a shielding effect is obtained by two orthogonal polarizing filters. May be used.
A lens 15 can be provided on the surfaces of the transmission polarization filter 1 and the reception polarization filter 2 as shown in FIG. The lens 15 may be provided inside the polarizing filters 1 and 2.
[0020]
As shown in FIG. 2, the polarization direction of the transmission polarization filter 1 and the polarization direction of the reception polarization filter 2 (indicated by arrows) are orthogonal to each other. Reference numeral 20 represents the vertical direction, and is assumed to be common to the optical communication device of the device that is the communication partner. In other words, the vertical direction 20 does not necessarily have to be perpendicular to the ground. In a situation where two devices are placed facing a large table, the vertical direction 20 is a normal direction from the table surface. Become.
The polarization direction of the transmission polarization filter 1 and the vertical direction 20 and the polarization direction of the reception polarization filter 2 and the vertical direction 20 are each configured at an angle of 45 degrees. There are two directions from the vertical direction 20 to 45 degrees, but the polarization direction of the counterpart device is the same.
[0021]
FIG. 3 shows a state in which two devices shown in FIG. In the figure, A01 shows another optical communication apparatus having the same configuration as the optical communication apparatus A shown in FIG. 2, and shows a state in which both apparatuses A and A01 are opposed to each other. By making them face each other, the transmission polarization filter 1 and the reception polarization filter 2 of the apparatus A are opposed to the reception polarization filter 201 and the transmission polarization filter 101 of the apparatus A01, respectively. In this state, the transmission polarization filter 1 and the reception polarization filter 201 facing each other, and the reception polarization filter 2 and the transmission polarization filter 101 are in a state in which their polarization directions coincide with each other.
[0022]
The optical signal 25 that has passed through the transmission polarization filter 1 is transmitted from the device A and received by the reception polarization filter 201 of the device A01. Since the polarization directions of the transmission polarization filter 1 and the reception polarization filter 201 coincide with each other, the device A01 can receive the optical signal 25 of the device A. Similarly, the optical signal 26 from the device A01 passes through the transmission polarization filter 101. Since this polarization direction matches the polarization direction of the reception polarization filter 2, the device A receives the optical signal 26 from the device A01. be able to. Since the polarization directions of the transmission polarization filter 1 and the reception polarization filter 2 and the transmission polarization filter 101 and the reception polarization filter 201 are orthogonal to each other, the optical signals are not received as described above.
[0023]
As an industrial product, it is preferable in terms of cost reduction and usability to unify all communication devices mounted on equipment in a single configuration method. According to the present invention, the polarization direction can be designed at 45 degrees and can be used in common for all devices. The angle 45 degrees from the vertical direction 20 described above is not strict and may be more than 30 degrees and less than 60 degrees.
When one or both of the devices shown in FIG. 3 are operated by being held in hand, for example, the direction of 45 degrees from the vertical direction cannot always be guaranteed, and a communication impossible state may occur. In such a case, the polarization direction can be changed manually or automatically, and its configuration is shown in FIG.
[0024]
FIG. 4 shows a second embodiment in which a circular optical shielding member 3 is rotatably fitted in a circular window 30 of the housing 6. As in FIG. 1, the optical shielding member 3 forms two chambers partitioned by a central partition 3a, and the transmission polarization filter 1 and the reception polarization filter 2 are attached to the openings of both chambers. Yes. The polarization directions of the transmission polarization filter 1 and the reception polarization filter 2 are orthogonal to each other. The rotation mechanism may be manual or automatic. As a method of automatically rotating, a mechanism using a weight attached to a position shifted from the center of rotation of the optical shielding member 3 and using the weight toward the ground can be used.
[0025]
FIG. 5 shows a third embodiment in which the transmission device and the reception device are configured separately, where T is a transmission device and R is a reception device. The transmission device T is provided with a pair of transmission polarization filters 1a and 1b, and a light emitting element (not shown) is provided inside. The receiving device R is provided with a pair of receiving polarizing filters 2a and 2b, and a light receiving element (not shown) is provided inside. The polarization direction of the transmission polarization filter 1a of the transmission device T coincides with the polarization direction of the reception polarization filter 2a of the reception device R and is orthogonal to the polarization direction of the transmission polarization filter 1b. Further, the polarization direction of the transmission polarization filter 1b of the transmission device T coincides with the polarization direction of the reception polarization filter 2b of the reception device R and is orthogonal to the polarization direction of the transmission polarization filter 1a. The optical signals 27 and 28 output from the transmission polarization filters 1a and 1b are 45 degrees with respect to the vertical direction 20.
[0026]
With the above configuration, the optical signal 27 that has passed through the transmission polarization filter 1a passes only through the reception polarization filter 2a and cannot pass through the reception polarization filter 2b. Similarly, the optical signal 28 that has passed through the transmission polarization filter 1b passes only through the reception polarization filter 2b and cannot pass through the reception polarization filter 2a. Thereby, two independent communication paths for the optical signals 27 and 28 can be realized. Separate protocol processing may be performed on these two communication paths, or a single communication path may be bundled to realize twice the communication capacity.
[0027]
FIG. 6 shows a fourth embodiment of a specific mode of the optical communication apparatus. Reference numeral 41 denotes a transmission unit, and 42 denotes a reception unit, which are controlled by the switching means 40. The switching unit 40 is in full-duplex mode or half-duplex mode. Light emitting elements 4a and 4b are provided inside the transmission polarization filters 1a and 1b, and light receiving elements 5a and 5b are provided inside the reception polarization filters 2a and 2b. The polarization directions of the transmission polarization filter 1a and the reception polarization filter 2b are the same, and the polarization directions of the transmission polarization filter 2a and the transmission polarization filter 1b are also the same. Further, the polarization directions of the transmission polarization filter 1a and the reception polarization filter 2a, and the transmission polarization filter 1b and the reception polarization filter 2b are orthogonal to each other, and are at an angle of 45 degrees from the vertical direction. Reference numeral 43 denotes a communication device.
[0028]
Next, the operation will be described. When the switching unit 40 is in the full duplex mode, the transmission unit 41 sends a transmission request from the communication device 43 only to the light emitting element 4a. The optical signal received by the light receiving element 5 a is selected by the receiving unit 42 and transmitted to the communication device 43. On the other hand, when the switching unit 40 is in the half-duplex mode, the transmission unit 41 sends a transmission request from the communication device 43 to the light emitting elements 4a and 4b. In addition, the optical signals received by the light receiving elements 5 a and 5 b are taken into the receiving unit 42 and notified to the communication device 43.
[0029]
Full duplex communication can be performed by using the light emitting element 4a and the light receiving element 5a, and half duplex communication can be performed by using the light emitting elements 4a and 4b and the light receiving elements 5a and 5b. By switching from the outside, it is possible to realize an optical communication apparatus that can handle full duplex and half duplex. In addition, the transmission unit 41 and the reception unit 42 may be operated so that the switching unit 40 is always in the half-duplex mode, and the switching unit 40 may be omitted.
[0030]
FIG. 7 shows a fifth embodiment in which a light emitting unit and a light receiving unit are provided in one polarizing filter, and a plurality of the polarizing filters are provided. A first polarizing filter 31 and a second polarizing filter 32 are provided at both openings of the optical shielding member 3. The polarization directions of the first polarizing filter 31 and the second polarizing filter 32 are orthogonal to each other. A light emitting element 4c and a light receiving element 5c are provided inside the first polarizing filter 31, and a light emitting element 4d and a light receiving element 5d are provided inside the second polarizing filter 32.
[0031]
The light shielding element 4c and the light receiving element 5d, and the light emitting element 4d and the light receiving element 5c are optically isolated by the optical shielding member 3. The light emitting element 4c and the light receiving element 5c, and the light emitting element 4d and the light receiving element 5d may or may not be optically isolated.
Next, the operation will be described. In communication, a light emitting element and a light receiving element in different polarizing plates are used in combination. For example, when the light emitting element 4c is used, the light receiving element 5d is used instead of the light receiving element 5c. When the light emitting element 4d is used, the light receiving element 5c is used and the light receiving element 5d is not used. When communication with the other device cannot be performed during communication, the light emitting / receiving combination is switched. If communication is interrupted due to a problem of the polarization direction, communication can be performed by this switching.
[0032]
【The invention's effect】
As described above in detail, according to the present invention, the optical blocking means is provided between the light emitting unit and the light receiving unit, and the polarization directions of the transmission polarization filter and the reception polarization filter are orthogonal to each other. When an optical communication device having the same configuration is faced, an optical signal emitted from one device is received by the other device, but does not reach the light receiving unit of the own device, and as a result, a full-duplex communication path Can be realized. Further, in a conventional light emitting / receiving module, full duplex communication can be performed at low cost with a simple configuration in which two transmission / reception polarizing filters are attached to the front surface of the optical shielding member.
The present invention can be applied to any analog communication / data communication, high-speed communication / low-speed communication, and an optical modulation method, and can be applied to, for example, an IrDA data method, an IrDA control method, and the like.
[Brief description of the drawings]
1A and 1B show a first embodiment of the present invention, in which FIG. 1A is a top view and FIG. 1B is a longitudinal sectional view;
FIG. 2 is a perspective view showing a state of polarization directions of a transmission polarization filter and a reception polarization filter.
FIG. 3 is a perspective view of a state where communication is performed with two sets of optical communication devices.
FIG. 4 is a perspective view showing a second embodiment.
FIG. 5 is a perspective view showing a third embodiment.
FIG. 6 is a block diagram showing a fourth embodiment.
7A and 7B are a plan view and a cross-sectional view showing a fifth embodiment.
FIG. 8 is a longitudinal sectional side view showing an embodiment in which a lens is provided.
FIG. 9 is an explanatory diagram showing a conventional protocol.
FIG. 10 is a longitudinal sectional view of a conventional optical communication device.
FIG. 11 is a perspective view of a conventional optical communication device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Transmission polarizing filter 2 Reception polarizing filter 3 Optical shielding member 4 Light emitting element 5 Light receiving element 17 Light emitting part 18 Light receiving part 20 Vertical direction 31 First polarizing filter 32 Second polarizing filter 40 Switching part A A01 Optical communication apparatus T Transmitting apparatus R Reception apparatus

Claims (6)

  A light emitting unit having a light emitting element and a transmission polarization filter provided in front of the light emitting element; a light receiving element and a light receiving unit having a reception polarization filter provided in front of the light receiving element and having a polarization direction orthogonal to the transmission polarization filter; An optical blocking member that is provided between the light emitting unit and the light receiving unit and prevents light from the light emitting unit from reaching the light receiving unit, and the polarization directions of the transmission polarization filter and the reception polarization filter are An optical communication apparatus, wherein an angle formed with a vertical direction is more than 30 degrees and less than 60 degrees.   The optical communication device according to claim 1, wherein the optical blocking member is rotatably attached to a housing, and the light emitting unit and the light receiving unit are integrated with the optical blocking member.   A plurality of light emitting parts having a light emitting element and a transmission polarization filter provided on the front surface of the light emitting element are provided separated by an optical blocking member, and the transmission polarization filter of each light emitting part has a polarization direction orthogonal thereto, An optical communication device comprising: a transmission device in which an angle between a polarization direction of a transmission polarization filter and a vertical direction is more than 30 degrees and less than 60 degrees.   A plurality of light receiving portions each having a light receiving element and a receiving polarization filter provided on the front surface of the light receiving element are provided separated by an optical blocking member, and the polarization direction of the receiving polarizing filter of each light receiving portion is orthogonal, An optical communication device comprising: a receiving device in which an angle between a polarization direction of a receiving polarizing filter and a vertical direction is more than 30 degrees and less than 60 degrees.   An optical communication apparatus comprising: the optical communication apparatus according to claim 3; and the optical communication apparatus according to claim 4. A transmission unit that provides a transmission signal to the light emitting element of the light emitting unit, a receiving unit that receives a signal from the light receiving element of the light receiving unit, a full duplex mode and a half duplex mode by controlling the light emitting unit and the light receiving unit and a switching means for switching, said switching means, when operating in full-duplex mode, one of simultaneously the receiving unit 1 when the light emitting elements of the light emitting portion Ru me give a transmission signal of the transmission unit to receive signals from the light receiving element of the light receiving unit, when operating in half-duplex mode, me give a transmission signal to the light emitting element of the two light-emitting portion of the transmission portion, the two light receiving unit to the receiving unit to receive signals from the light receiving element, the optical communication apparatus according to claim 5, wherein the transmit and receive and wherein Rukoto performed exclusively.

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