JPH0669886A - Light space transmission device - Google Patents

Abstract

PURPOSE:To easily and accurately correct the irradiation position deviation of laser beam between a transmission unit and a reception unit from a wide range of angles by permitting a transmission unit itself to perform the correction by the beam irradiation position deviation detection light from the reception unit. CONSTITUTION:A light emitting diode detection light L of the reception unit is made incident to a case 40a. When the light axis of laser beam is largely deviated, the only L1 passing a half mirror 40e is made incident into a photosensor 91A and inputted to a differentiator. With the differential signal, an actuator is driven to correct the light axis largely deviated. When the deviation is made smaller, L2 reflected by a mirror 40e is made incident to a photosensor 91F to output the differential signal from a 2nd differentiator. According to the gain, the fine adjustment of the actuator is performed. Thus, the light axis deviation detection destination is outputted from the reception unit and when the transmission unit corrects the position deviation, not so much movement amount of the reception unit is required and the correction of the light axis deviation can be performed from a wide range of angles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for transmitting information such as video and audio in an optical space.

[0002]

2. Description of the Related Art Conventionally, as a method for transmitting information such as video and audio in an optical space, for example, Japanese Patent Laid-Open No. 1-236871.
Japanese Patent Application Laid-Open No. 3-2148881 and Japanese Patent Application Laid-Open No. 3-21488
Each publication such as 882 discloses a method of FM-modulating the light output from an infrared LED and transmitting the FM-modulated light.

However, since the light output from the infrared LED is diffused light, it is possible to cover a wide range of positional deviation between the transmitting side and the receiving side, but the amount of light is attenuated by diffusion, so the transmission distance is limited. However, when using a plurality of devices, there is a problem that signals of the devices interfere with each other. In addition, when used indoors, light is diffusely reflected on the ceiling, walls, floor, etc., and noise occurs in the case of high frequency signals, so there is a problem that the upper limit of the modulation frequency cannot be set high.

Therefore, if the laser light is modulated by a predetermined information signal and spatially transmitted, the laser light can be prevented from being diffused by forming the laser light into a parallel beam by a collimating lens or the like, and the above-mentioned problem is solved. be able to. However, on the other hand, since the laser beam is made into a parallel beam, when the relative position between the transmitting side and the receiving side is deviated, the transmission of information is hindered. It will be necessary to correct it.

In response to this, JP-A-59-14314
No. 4 publication proposes an optical space transmission device configured so that, when the direction of a laser beam from the transmitter side is changed, the light receiving unit on the receiver side always moves while tracking the optical space. ing.

[0006]

However, in such a conventional optical space transmission device, even if the direction of the laser beam is slightly deviated, the larger the transmission distance between the transmitter and the receiver is, the more the reception becomes. The light receiving unit on the machine side cannot capture the laser beam unless it moves largely. That is, when the length of the laser beam is the radius, the length of the arc with respect to the rotation angle in that direction is the amount of movement of the light receiving portion. For this reason, there is a problem that the device becomes large in size in order to make it movable even if the amount of movement of the light receiving unit becomes large, and a small receiving device cannot perform long-distance optical space transmission.

[0007]

In order to solve the above-mentioned problems, the present invention provides a transmitting unit for outputting a laser beam modulated based on a predetermined information signal, and a receiving unit for receiving and demodulating the laser beam. And, the receiving unit has a light source that outputs detection light for detecting an irradiation position deviation of the laser beam toward the transmitting unit,
The transmission unit includes a light receiving unit that receives the detection light and detects the irradiation position deviation amount, and a correction unit that corrects the irradiation position deviation based on a detection signal from the light receiving unit. The means includes a coarse movement detection unit that detects a large irradiation position deviation amount, a fine movement detection unit that detects an irradiation position deviation amount that is smaller than the coarse movement detection unit, and the detected light received by the coarse movement detection unit and the fine movement detection unit. An optical system for splitting light is provided to the usage detection unit.

[0008]

According to the optical space transmission device having such a configuration, the detection light for detecting the irradiation position deviation (optical axis deviation) of the laser beam from the transmission unit is output from the light source of the reception unit, and the transmission unit detects it. The light is received and the correction unit corrects the irradiation position shift. As described above, since the transmitting unit itself performs the correction operation by the detection light from the receiving unit, the receiving unit does not need to move largely, and thus even a small receiving unit can perform long-distance optical space transmission.

Further, at this time, the light receiving means of the transmitting unit which receives the detection light splits the detection light into two by the optical system, inputs one of them into the coarse movement detection section, and receives the other one. Input to the detection unit for fine movement. Further, since the coarse movement detection unit detects a large irradiation position deviation amount of the laser beam, it is possible to detect a wide-angle irradiation position deviation, and the fine movement detection unit irradiates a laser beam smaller than the coarse movement detection unit. Since the amount of positional deviation is detected, a fine and accurate irradiation positional deviation can be finally detected. Therefore, it is possible to easily correct the irradiation position deviation of the laser beam between the transmission unit and the reception unit, and it is possible to correct the irradiation position deviation accurately from a wide angle range.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of an optical free space transmission apparatus according to the present invention. FIG. 1 is a diagram showing an outline of an optical space transmission apparatus, in which reference numeral 1 is a transmission apparatus (transmission unit) thereof, and 3 is a reception apparatus (reception unit) thereof. Terminal devices such as a personal computer 2 and a printer 4 are connected to the transmission unit 1 and the reception unit 3 by wire, and information from the terminal device on the transmission unit 1 side is transmitted between the transmission unit 1 and the reception unit 3. It is transmitted to the terminal device on the receiving unit 3 side by the optical space transmission performed. It should be noted that the transmitting unit 1 is connected to a video reproducing device, which will be exemplified later, in place of such terminal equipment, and the receiving unit 3 is connected to a television receiver, which is exemplified later, in place of such terminal equipment. May be.

FIG. 2 is a block diagram showing a schematic configuration of the transmission unit 1 and the reception unit 3 shown in FIG. The transmission unit 1 is, for example, from a video output terminal of a video playback device (not shown), a video signal input via the jack 51 and the signal cable 5, and an audio output terminal of the video playback device (not shown). An FM modulation circuit 11 that modulates L and R audio signals input via the jacks 52 and 53 and the signal cable 5, and a laser driver that drives the laser diode 13 to emit light based on the modulation signal from the FM modulation circuit 11. 12 and 12.

The laser diode 13 outputs a laser beam in the visible light region for information transmission, and is held by an actuator 14 which can be swung vertically and horizontally. The actuator 14 is an actuator driver 15
Driven by the actuator 14, the irradiation direction of the laser beam output from the laser diode 13 is swung in the vertical and horizontal directions to be corrected.

Reference numeral 16 in FIG. 2 denotes a positional deviation detector, which indicates the amount of positional deviation between the irradiation position of the laser beam from the laser diode 13 and the light receiving element 31 on the receiving unit 3 side that receives this laser beam. To detect. Then, the actuator driver 15 determines the vertical and horizontal turning amounts of the actuator 14 based on the positional shift amount detected by the positional shift detector 16.

Further, reference numeral 17 in FIG. 2 denotes a laser safety circuit, which is provided with a light receiving element (not shown) for detecting an obstacle, and the light receiving element is a light emitting diode 33 (corresponding to a light source) of the receiving unit 3 described later. When the received light amount of the detection light output from the device is reduced or becomes zero, or when the photodetectors 91A and 91B provided in the light receiving units 40A and 40B (see FIG. 3) of the positional deviation detector 16 detect the light emitting diode 3
The actuator driver 15 is controlled so that the output of the laser beam from the laser diode 13 is stopped when the received light amount of the detection light from 3 becomes zero.

On the other hand, the receiving unit 3 demodulates the light receiving element 31 that receives the laser beam from the laser diode 13 through the filter 34, and the laser beam received by the light receiving element 31 to obtain a video signal of the demodulated signal. Is output to a video input terminal of, for example, a television receiver (not shown) via the signal cable 7 and the jack 71, and the L and R audio signals of the demodulated signal are output to the signal cable 7 and the jacks 72 and 73. A demodulation circuit 32 for outputting to a sound input terminal of the television receiver (not shown) through a light emitting diode 33 for outputting detection light for detecting a laser beam irradiation position shift by the position shift detector 16. I have it.

FIG. 3 is an external perspective view of the transmission unit 1. A cylindrical holder 38 is provided on the front surface of the housing 20.
The laser diode 13 is held in the holder 38. On both sides of the holder 38, light receiving units (light receiving means) 40A, 40 of the displacement detector 16 are provided.
B is held, and the light receiving unit 40A on the right side in the figure is provided with a photo sensor 91A for receiving the detection light L from the light emitting diode 33 by the sensor sections divided into the upper and lower parts. The unit 40B is provided with a photo sensor 91B that receives the detection light L by a sensor unit that is split into two left and right units.

The light receiving unit 40A is provided in a cylindrical case 40a whose front and rear are closed, as shown in detail in FIG. That is, the front surface of the case 40a (upper surface in the figure)
A pinhole 40b is opened in the rear surface of the case 40a, and a photosensor 91A (coarse movement detection portion) is formed on the rear surface (lower surface in the figure) of the case 40a.
Is provided. Further, a photo sensor 91F (fine movement detection unit) smaller than the photo sensor 91A is provided on the side portion of the case 40a. A coarse movement lens 40c is provided in the front part of the photo sensor 91A.
A fine movement lens 40d is provided in the front part of 1F. A half mirror 40e inclined by 45 ° with respect to the axis of the case 40a is provided between the coarse movement lens 40c and the fine movement lens 40d. The light receiving unit 40B has the same configuration.

FIG. 5 is a partially cutaway enlarged perspective view showing a schematic structure of the actuator 14. In front of the laser diode 13 of the holder 38, a collimator lens 18 that shapes the laser beam output from the laser diode 13 into a parallel light flux is held. Holding pieces 38 for holding the light receiving units 40A and 40B are provided on both sides of the holder 38.
a extends, and the holder 38 and the holding piece 38a are connected to the sub-frame 4 via the support shaft 38b and the bearing 42a.
2, it is supported so as to be rotatable in the left-right direction.

On the inner peripheral surface of the sub-frame 42, the holder 3
8 is rotated to the left and right with respect to the sub-frame 42,
A permanent magnet 45a of the voice coil motor 45 is attached, and a coil 45b of the voice coil motor 45 attached to the rear end of the holder 38 faces the permanent magnet 45a. Then, the sub-frame 42 includes the support shaft 42.
main frame 58 through b and bearing 58a
It is supported so as to be vertically rotatable.

A permanent magnet 48a of a voice coil motor 48 for rotating the sub-frame 42 in the vertical direction with respect to the main frame 58 is attached to the inner peripheral surface of the main frame 58. The permanent magnet 48a has a sub-magnet. A coil 48b of a voice coil motor 48 attached to the rear end of the frame 42 is exposed.

The voice coil motors 45 and 48
Is a coil 45b by the actuator driver 15,
With the energization of 48b, its permanent magnets 45a, 48a
The electromagnetic force generated in relation to the magnetic field causes the holder 38 to which the coils 45b and 48b are attached and the sub-frame 42 to swivel left and right and up and down. In this embodiment, the holder 38, the sub-frame 42, the voice coil motors 45 and 48, and the main frame 58 constitute the actuator 14, and the actuator 14 and the actuator driver 15 constitute the correction means.

FIG. 6 is a diagram showing a processing circuit for signals from the upper and lower two sensor portions of the photosensor 91A and the photosensor 91F in the light receiving unit 40A. In the figure, reference numerals 22 and 23 are differentiators, 25 is a sensor switch, and 27 is a gain controller, which are connected as shown.

Next, the operation of the optical free space transmission apparatus of this embodiment will be described. When a video signal or L and R audio signals are input to the FM modulation circuit 11 from a video reproducing device (not shown) via the signal cable 5 and the jacks 51 to 53, the video and audio signals are FM-modulated. It is input to the laser driver 12. Then, laser diode 1
The laser beam output from the receiving unit 3 is modulated by the laser driver 12 based on this modulation signal.
It is output toward the light receiving element 31 of.

The light receiving element 31 which has received the laser beam from the laser diode 13 demodulates the received light signal into the demodulation circuit 3
2, and the demodulation circuit 32 demodulates the signal, and the demodulated video signal and L and R audio signals are input to, for example, an input terminal of a television receiver via the signal cable 7 and the jacks 71 to 73. Output.

By the way, at this time, the light emitting diode 33 of the receiving unit 3 outputs the detection light toward the transmitting unit 1 at a predetermined spread angle, and the detection light is received by the light receiving units 40A and 40B of the transmitting unit 1. The photosensors 91A, 91B and 91F are illuminated. Therefore, during the output of the laser beam from the laser diode 13, the relative positions of the transmitting unit 1 and the receiving unit 3 are displaced, and the optical axis direction of the laser beam from the laser diode 13 is the center of the light receiving element 31. When it is deviated from (deviation of irradiation position), the direction of the deviation is the light emitting diode 33.
The output signals of the photosensors 91A, 91B, and 91F that have received the detection light from are detected by the signal processing circuit of FIG. Then, the actuator driver 1 based on the detection result
The actuator 14 is driven by the control operation of 5,
The optical axis direction of the laser beam from the laser diode 13 held by the holder 38 is corrected so as to coincide with the center of the light receiving element 31.

As described above, since the transmitting unit itself performs the correction operation by the detection light from the receiving unit, it is possible to easily correct the irradiation position deviation of the laser beam without moving the receiving unit largely, and even a small receiving unit has a long distance. It becomes possible to perform the optical space transmission.

Next, the detection operation of the photosensors 91A and 91F of the light receiving unit 40A will be described with reference to FIGS. When the relative position of the transmitting unit 1 and the receiving unit 3 is tilted and the optical axis of the laser beam is largely deviated from the center of the light receiving element 31, when the light emitting diode 33 of the receiving unit 3 outputs the detection light, FIG. ), The detection light L is greatly inclined and the pinhole 40
The first detection light L1 that has entered the case 40a from b and passed through the half mirror 40e is refracted by the coarse movement lens 40c and received by the photosensor 91A, but the second detection light L2 reflected by the half mirror 40e. Goes in a direction far away from the fine movement lens 40d.

In this case, the received light signal is input to the difference unit 22 only from the photo sensor 91A, and the received light signal is not input to the difference unit 23 from the photo sensor 91F. For this reason,
The differential signal from the differentiator 22 is taken out by the sensor switch 25 and sends a signal to the gain controller 27 so as to obtain a gain corresponding to it. The signal amplified by the gain controller 27 is input to the actuator driver 15, and the actuator driver 15 drives the actuator 14 to largely correct the optical axis of the laser beam.

When the optical axis of the laser beam is largely corrected and the deviation amount of the optical axis is reduced, the detection light L is incident on the case 40a with a slight inclination as shown in FIG. The passed first detection light L1 passes through the coarse movement lens 40c and is received by the substantially central portion of the photosensor 91A, while the second detection light L2 reflected by the half mirror 40e enters the fine movement lens 40d. The light is refracted by the fine movement lens 40d and is received by the photosensor 91F.

In this case, in the photo sensor 91A, due to the problem of the gap between the two divided sensors, the actuator 14
6 becomes unstable, the sensor switch 25 in FIG. 6 extracts the difference signal from the difference unit 23 instead of the difference signal from the difference unit 22, and the gain controller 27 uses the difference signal for the photo sensor 91F. The actuator driver 15 finely adjusts the actuator 14 based on the signal amplified by the set gain so that the optical axis of the laser beam is accurately received.
Match the center of 1. Especially in this case, the photo sensor 9
By using the photo sensor 91F smaller than 1A for detection, the detection processing time is short and the actuator 14 can be driven at high speed.

While the light receiving unit 40A as described above corrects the optical axis shift of the laser beam in the vertical direction, the light receiving unit 40B operating similarly can correct the shift of the optical axis of the laser beam in the horizontal direction. .

FIG. 8 is a diagram showing another embodiment of the optical free space transmission apparatus according to the present invention. In the above embodiment, two light receiving units 40A and 40B having two-division type photosensors 91A and 91B for receiving the detection light from the light emitting diode 33 are provided on both sides of the holder 38, while the laser beam light is emitted. In the present embodiment, the light receiving unit 41 having the four-division type photo sensor 93 is provided on only one side of the holder 38, while the vertical deviation of the shaft and the other lateral deviation are detected. The one photo sensor 93 receives the detection light L and detects the deviation of the optical axis of the laser beam in the vertical and horizontal directions.

In this embodiment as well, in the light receiving unit 41, in addition to the photosensor 93 (coarse movement detection portion) provided at the abutting portion, a photosensor (fine movement detection portion) (not shown) smaller than the photosensor 93 is provided on the side. The optical system 40c, 40d of the light receiving unit 40A,
It has the same optical system as 40e. When the optical axis shift is large, the photosensor 93 detects it to make a large correction, and when the optical axis shift is small, the small photosensor on the side detects and makes a fine adjustment to make an accurate correction. It is possible.

In the above embodiment, the two-division type or four-division type photosensor was used, but instead of them,
A sensor such as a position sensor diode (PSD) that detects a light receiving position may be used, which makes it possible to realize a correction operation rich in high speed.

[0035]

As described above, according to the present invention, it is possible to perform long-distance optical space transmission even with a small receiving unit, and a coarse movement detecting section detects a wide-angle irradiation position shift. Further, it is possible to detect a fine and accurate irradiation position shift by the fine movement detection unit.
Therefore, it is possible to easily correct the irradiation position deviation of the laser beam between the transmission unit and the reception unit, and it is possible to correct the irradiation position deviation accurately from a wide angle range.

Further, since the photo sensor 91F used is smaller than the photo sensor 91A, the detection operation can be performed at high speed, and the PSD can be used for higher speed detection. Therefore, since the detection can be performed at high speed, accurate optical axis correction can be performed even when the transmitting unit 1 and the receiving unit 3 are moving.

[Brief description of drawings]

FIG. 1 is a layout diagram showing an outline of an optical space transmission device.

FIG. 2 is a block diagram showing a schematic configuration of a transmission unit 1 and a reception unit 3 of an optical free space transmission apparatus according to an embodiment of the present invention.

3 is a partially cutaway perspective view of the transmission unit 1 shown in FIG.

FIG. 4 is a sectional view showing a configuration of a light receiving unit 40A shown in FIG.

5 is a partially cutaway enlarged perspective view showing a schematic configuration of an actuator 14 shown in FIG.

FIG. 6 is a photo sensor 91 in the light receiving unit 40A.
It is a processing circuit diagram of the signal from each divided sensor part of A and 91F.

7 is a diagram showing the operation of the light receiving unit 40A shown in FIG. 4, and FIG. 7 (a) is a diagram showing the states of the spectra L1 and L2 of the detection light L when the optical axis of the laser beam is largely deviated. FIG. 7B is a diagram showing the states of the spectra L1 and L2 of the detection light L when the deviation of the optical axis of the laser beam becomes small.

FIG. 8 is a partially cutaway perspective view of a transmission unit 1 of an optical free space transmission apparatus according to another embodiment of the present invention.

[Explanation of symbols]

 1 Transmitting Unit 2 Personal Computer 3 Receiving Unit 4 Printer 5,7 Signal Cable 11 FM Modulating Circuit 12 Laser Driver 13 Laser Diode 14 Actuator 15 Actuator Driver 16 Position Deviation Detector 17 Laser Security Circuit 18 Collimating Lens 20 Housing 22, 23 Differencer 25 Sensor switch 27 Gain controller 31 Light receiving element 32 Demodulation circuit 33 Light emitting diode 34 Filter 38 Holder 40A, 40B, 41 Light receiving unit 42 Subframe 42a Bearing 45 Voice coil motor 45a Permanent magnet 45b Coil 48 Voice coil motor 48a Permanent magnet 48b Coil 51 to 51 53 jacks 58 main frame 58a bearings 71 to 73 jacks 91A, 91B, 93 photo sensor L Detection light L1 First detection light L2 Second detection light

Claims (1)

[Claims] 1. A transmitter unit for outputting a laser beam modulated based on a predetermined information signal, and a receiver unit for receiving and demodulating the laser beam, wherein the receiver unit irradiates the laser beam. A light source that outputs detection light for detecting a deviation toward the transmission unit, the transmission unit receives the detection light and detects the irradiation position deviation amount, and detection from the light reception means. A correction unit that corrects the irradiation position shift based on a signal, and the light receiving unit detects a coarse movement detection unit that detects a large irradiation position shift amount and an irradiation position shift amount that is smaller than the coarse movement detection unit. An optical space transmission device, comprising: a fine movement detection section; and an optical system that splits the received detection light into the coarse movement detection section and the fine movement detection section.