JP2001320331A - Optical space transmitting device and image monitor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the transmission of a moving image and sound hardly interruptable, even if a meteorological condition, etc., worsens and to also transmit the moving image and the sound with high quality in a normal mode. SOLUTION: A moving image picked up by a camera 10 is subjected to encoding processing, including data compression processing with an encoding processing circuit 12, after A/D conversion. An optical signal modulated with the encoded data is outputted from a light-emitting element 14. The optical signal is received by a light-receiving element at a remote place and subjected to decoding processing or the like, a moving image obtained by the decoding processing is displayed on a monitor and the image is monitored. Another optical signal transmitted through a spatial transmission path is received by a light-receiving element 17, and the light reception level is detected by a detection circuit 22. The transfer speed (= transmission speed) of the circuit 12 is adjusted according to the light receiving level. Encoding by the circuit 12 is performed with a quality corresponding to the transfer speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical space transmission apparatus for transmitting information of at least one of a moving image and a sound, and an image monitoring apparatus using the same.

[0002]

2. Description of the Related Art A free-space optical transmission apparatus transmits information using light as a transmission medium without using a cable such as an optical fiber. A rich device can be realized, and information can be transmitted even in a place where it is difficult to lay cables.

In the conventional optical space transmission apparatus, the transmission speed is fixed at a constant speed.

[0004]

In order to transmit a moving image or a voice with high quality by the free space optical transmission device, it is necessary to set the transmission speed of the free space optical transmission device to a high speed. For this reason, when transmitting a moving image or sound using the conventional optical space transmission device, the transmission speed is usually set to a relatively high speed.

However, in the optical space transmission apparatus, a light emitting element such as an LED or a laser diode is used for transmitting an optical signal, and a light receiving element such as a photodiode is used for receiving an optical signal. The photoelectric conversion efficiency of these optical elements decreases as the modulation speed, and thus the transmission speed, increases, and increases as the transmission speed decreases. That is, when the transmission speed is increased, the intensity of the output light is not sufficiently increased due to the response time of the light emitting element, and the sensitivity of the light receiving element is reduced.

[0006] The transmittance of light in the spatial transmission path of the optical space transmission apparatus decreases due to weather conditions such as generation of dense fog, heavy rain, and heavy snow.

Therefore, in the conventional optical space transmission apparatus, since the transmission speed is fixed at a constant speed, the transmission speed is set to a relatively high speed in order to transmit moving images and audio with high quality as described above. In such a case, since the photoelectric conversion efficiency of the optical element is reduced, if the light transmittance of the spatial transmission path is reduced due to weather conditions, transmission is likely to be interrupted. For this reason,
For example, when a conventional optical space transmission device is used in an image monitoring device, a moving image captured by an imaging device is transmitted to a remote monitoring location by the optical space transmission device, and is displayed on a monitor such as a CRT installed at the monitoring location. In some cases, a monitoring image may not be displayed on a CRT or the like at all depending on weather conditions, and appropriate monitoring becomes impossible, which is fatal.

Therefore, it is conceivable to set a low transmission speed in the conventional optical space transmission apparatus. In this case, the photoelectric conversion efficiency of the optical element is increased, and even if the light transmittance of the spatial transmission path is reduced due to the influence of weather conditions, the transmission is not easily interrupted.

However, in the conventional optical space transmission apparatus,
Since the transmission speed is fixed at a constant speed, in this case, even if the weather conditions are good, the transmission speed remains low, so that high-quality moving images and audio cannot be transmitted. However, the quality of moving images and sounds must always be reduced.

The present invention has been made in view of such circumstances, and it is difficult to interrupt transmission even when weather conditions and the like deteriorate, and it is also possible to transmit moving images and sounds with high quality in normal times. It is an object to provide an optical space transmission device and an image monitoring device using the same.

[0011]

According to a first aspect of the present invention, there is provided an optical space transmission apparatus for transmitting at least one of moving picture and sound information. It comprises a transmitting device, a receiving device, and detecting means. The transmission device includes an encoding unit that performs an encoding process including a data compression process on the information, and a transmission unit that transmits an optical signal modulated by the data encoded by the encoding unit. A receiving unit that receives the optical signal transmitted from the transmitting unit and demodulates the encoded data; and a decoding unit that performs a decoding process including a data expansion process on the demodulated data. Means. The detecting means detects a state of a spatial transmission path of the optical signal. The encoding means and the transmission means, the transmission by the optical signal is performed at a transmission rate adjusted according to the detection signal from the detection means, and the information is encoded with a quality corresponding to the transmission rate. ,Operate.

According to the first aspect, the transmission rate is adjusted by the encoding means and the transmission means in accordance with the state of the spatial transmission path, and the moving image and audio are transmitted with a quality corresponding to the transmission rate. Will be.

Therefore, when the transmission characteristics of the spatial transmission path deteriorate due to weather conditions or the like (for example, when the light transmittance of the spatial transmission path decreases), if the transmission speed is reduced, the weather conditions and the like can be reduced. Is worse, the photoelectric conversion efficiency of the optical element is increased, so that it is difficult to interrupt the transmission. In this case, when weather conditions and the like deteriorate, moving images and voices are transmitted at a quality corresponding to the reduced transmission speed, so the quality is reduced. Since the transmission of the data can be secured, the merit is great. On the other hand, when the transmission characteristics of the spatial transmission path are good, the transmission speed increases, and moving images and audio are transmitted with high quality corresponding to the transmission speed.

As described above, according to the first aspect, transmission is hard to be interrupted even when weather conditions and the like deteriorate, and high-quality moving images and sounds are transmitted at normal times when weather conditions and the like are good. be able to.

According to a second aspect of the present invention, there is provided the optical free space transmission apparatus according to the first aspect, wherein the detecting means includes a transmitting means for transmitting a second optical signal from the receiving device side to the transmitting device side. And a light intensity detecting means provided on the transmitting device side for detecting the light intensity of the second optical signal.

In the second embodiment, an example of a detecting means for detecting a state of a spatial transmission path is given. The second optical signal may be a simple measurement light that does not contain information (that is, is not modulated), or may be a signal light that contains some information (that is, is modulated).

According to a third aspect of the present invention, in the optical space transmission apparatus according to the first aspect, the detecting means includes a reflecting means for reflecting a part of an optical signal transmitted by the transmitting means on the receiving device side. And light intensity detection means provided on the transmission device side and detecting the light intensity of the optical signal reflected by the reflection means.

According to the third aspect, unlike the second aspect, there is no need to provide a special light source or the like for detecting the state of the spatial transmission line, so that the configuration is simple and inexpensive.

An optical space transmission apparatus according to a fourth aspect of the present invention, in the first aspect, includes a light intensity detecting means provided on the receiving device side for detecting the light intensity of the optical signal.

According to the fourth aspect, since the optical signal is directly detected by the light intensity detecting means provided on the receiving device side, the optical signal of the optical signal can be detected with higher accuracy than in the third aspect. This is preferable because the state of the spatial transmission path can be detected. It is necessary to send a detection signal from the light intensity detection means or a signal based on the detection signal (for example, a level discrimination signal) to the transmission device side. A transmission device such as a spatial transmission device can be used.

According to a fifth aspect of the present invention, there is provided an image monitoring apparatus, comprising: an imaging unit; an optical space transmission device for transmitting a moving image captured by the imaging unit; and a moving image transmitted by the optical space transmission device. Display means for displaying. The optical space transmission device, a transmitting device, a receiving device,
Detecting means. The transmitting device transmits an optical signal modulated by data encoded by the encoding unit, the encoding unit performing an encoding process including a data compression process on a moving image captured by the imaging unit. Transmission means. A receiving unit that receives the optical signal transmitted from the transmitting unit and demodulates the encoded data; and a decoding unit that performs a decoding process including a data expansion process on the demodulated data. Means. The detecting means detects a state of a spatial transmission path of the optical signal. The encoding unit and the transmission unit perform transmission by the optical signal at a transmission rate adjusted according to a detection signal from the detection unit, and encode the moving image with a quality corresponding to the transmission rate. Then, it works.

The fifth aspect is an image monitoring apparatus provided with the same optical space transmission device as that of the first aspect, and the moving image captured by the imaging device is transmitted and displayed by the optical space transmission device. Displayed on the device. Therefore, according to the fifth aspect, even when the weather conditions and the like deteriorate, the quality of the moving image is reduced, but the transmission is hard to be interrupted. Can be displayed on the display device with high quality.

The image monitoring apparatus according to a sixth aspect of the present invention is the image monitoring apparatus according to the fifth aspect, wherein the detecting means transmits a second optical signal from the receiving apparatus to the transmitting apparatus; Light intensity detecting means provided on the transmitting device side for detecting the light intensity of the second optical signal.

In the sixth embodiment, similar to the second embodiment, an example of the detecting means for detecting the state of the spatial transmission path is given. The second optical signal may be a simple measurement light that does not contain information (ie, is not modulated),
It may be a signal light containing some information (that is, modulated) as in a seventh aspect described later.

According to a seventh aspect of the present invention, in the image monitoring apparatus according to the sixth aspect, the second optical signal includes a control signal for controlling the image pickup means. Examples of the control include zooming of the imaging unit, movement of the field of view, start / end of imaging, turning on / off a wiper of the imaging window, and the like.

According to the seventh aspect, there is no need to provide a special light source or the like for detecting the state of the spatial transmission path, so that the configuration is simple and inexpensive.

An image monitoring apparatus according to an eighth aspect of the present invention is the image monitoring apparatus according to the fifth aspect, wherein the detecting means includes a reflecting means for reflecting a part of the optical signal transmitted by the transmitting means on the receiving device side. And a light intensity detecting means provided on the transmitting device side for detecting the light intensity of the optical signal reflected by the reflecting means.

According to the eighth aspect, there is no need to provide a special light source or the like for detecting the state of the spatial transmission path, so that the configuration is simple and inexpensive.

According to a ninth aspect of the present invention, in the image monitoring apparatus according to the fifth aspect, the detecting means includes a light intensity detecting means provided on the receiving device side for detecting the light intensity of the optical signal. It is a thing.

According to the ninth aspect, since the optical signal is directly detected by the light intensity detecting means provided on the receiving device side, the optical signal of the optical signal can be detected more accurately than in the seventh aspect. This is preferable because the state of the spatial transmission path can be detected.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image monitoring apparatus according to an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a schematic block diagram showing a first device 1 constituting an image monitoring device according to the present embodiment.
FIG. 2 is a schematic block diagram showing a second device 2 constituting the image monitoring device according to the present embodiment.

The image monitoring apparatus according to the present embodiment includes a first apparatus 1 installed near a place where an image is captured and a first apparatus 1 installed near a monitoring place where a monitoring person monitors the image while watching the captured image. 2 device 2.

As shown in FIG. 1, a first device 1 includes a television camera 10 serving as an image pickup means for picking up a monitoring image and outputting an analog image signal such as an NTSC signal, and an image signal (moving image) A / D conversion of A / D
A D conversion circuit 11, an encoding processing circuit 12 for encoding A / D converted moving image data, and a light emitting element 1 such as an LED
4, a driving circuit 13 for driving the light emitting element 14 in accordance with the data encoded by the encoding processing circuit 12, and an optical system 15 for outputting the first optical signal emitted from the light emitting element 14 to the outside. ing. Note that the camera 10 may output a digital image signal, in which case the A / D conversion circuit 11 is unnecessary. Further, a laser diode or the like can be used as the light emitting element 14.

The encoding processing circuit 12 performs information source encoding processing (data compression processing) on A / D-converted moving image data and communication path encoding such as error correction encoding on the compressed data. Processing, for example,
It can be configured using a DSP (Digital Signal Processor), a buffer memory, and other memories.
As the compression processing, various methods can be adopted. For example, as is well known, inter-frame prediction, DC
Processing by an algorithm including block conversion by T, quantization, and the like can be adopted. In particular,
The encoding processing circuit 12 is, for example, an H.264 standard which is an encoding standard for videophone / videoconference. 263 can be adopted.

In the present embodiment, the encoding processing circuit 12 transfers the encoded data at a transfer rate (bit / sec) according to a signal from a light receiving level determination circuit 23 described later.
, And encodes the A / D-converted moving image data with a quality suitable for the transfer speed. That is, in the present embodiment, the encoding processing circuit 12 is configured to perform so-called rate control so that the transfer speed becomes the transfer speed according to the signal from the light reception level determination circuit 23. To briefly explain this point, in the information source coding (data compression processing), variable length coding is performed, the coded data is temporarily stored in a buffer memory, and the data stored in the buffer memory is temporarily stored. Is the light receiving level determination circuit 2
3 is read out and output at a transfer speed corresponding to 3. At this time, in order to prevent the buffer memory from overflowing or underflowing, for example, the quality of the frame itself is changed by changing the fineness of the quantization, the resolution of the image (image size) is changed, or the frame is changed. The quality of the moving image is adjusted by performing the so-called frame dropping by deleting the frame. In the present invention, for example, the quality of encoding of moving image data may be adjusted by changing at least one of the quality of a frame itself, the resolution of an image, and the number of frames per unit time (the number of frames). .

In this embodiment, the light receiving level judgment circuit 2
Signals in three to two stages are supplied to the encoding processing circuit 12, and the encoding processing circuit 12 outputs data encoded at any one of two transfer speeds. However, a signal having three or more steps or a continuous signal having no steps is supplied from the light receiving level determination circuit 23 to the encoding processing circuit 12, and the encoding processing circuit 12 has three or more types or a continuous transfer rate having no steps. May be configured to output the data coded in.

In the present embodiment, the drive circuit 13 drives the light emitting element 14 on and off according to the data 1, 0 encoded by the encoding processing circuit 12. By the direct modulation, the first optical signal modulated by the output data of the encoding processing circuit 12 and including the moving image information is converted into the second optical signal shown in FIG.
Is output to the device 2. Therefore, in the present embodiment, the transfer speed of the encoding processing circuit 12 is the transfer speed of the first optical signal. As can be understood from the above description, in the present embodiment, the driving circuit 13 and the light emitting element 14
And the optical system 15 constitute a transmission unit for transmitting a first optical signal modulated by the data encoded by the encoding processing circuit 12. However, in the present invention, any modulation other than direct modulation, for example, frequency modulation or the like may be adopted. In such a case, for example, a modulation circuit corresponding to the modulation method is inserted between the encoding processing circuit 12 and the driving circuit 13, and the second device 2 shown in FIG. What is necessary is just to insert a demodulation circuit corresponding to the modulation method between the decoding processing circuit.

As can be seen from the above description, the elements 11 to 15 in FIG. 1 constitute a transmission device for transmitting a moving image captured by the camera 10. This transmitting device constitutes an optical space transmission device together with a receiving device constituted by elements 30 to 39 in FIG. 2 to be described later.

Next, referring to FIG. 2, the second device 2
A light receiving element 31 such as a photodiode for receiving the first optical signal transmitted from the first device 1;
An optical system 30 that guides the optical signal to the light receiving element 31, a load resistance control circuit 32 for extracting the photoelectrically converted output of the light receiving element 31, and an amplifier circuit 3 that amplifies the extracted output.
3, filters 34 and 35, and transmission speed detection circuit 36
1, the channel decoding process and the information source decoding process (data compression process) corresponding to the channel encoding process and the information source encoding process (data compression process) performed by the encoding process circuit 12 in FIG. Decoding processing circuit 38 for performing data decompression processing)
A D / A conversion circuit 39 for D / A converting the moving image data decoded by the decoding processing circuit 38; and a display means for displaying a moving image indicated by the D / A converted image signal (moving image signal) And a television monitor 40.

The transmission rate detection circuit 36 detects the transmission rate based on the output of the amplifier circuit 33, and is constituted by using, for example, a counter. The detection signal from the transmission speed detection circuit 36 is supplied to the load resistance control circuit 32 and the switch 37, respectively. Load resistance control circuit 32
Although not shown in the drawing, a load resistor having a resistance value optimized according to the detected transmission speed (that is, the sensitivity of the light receiving element 31 is the highest) is selectively connected to the light receiving element 31. I do. Each of the filters 34 and 35 is a band-pass filter having a pass frequency band corresponding to each transmission speed (in the present embodiment, as described above, two types of transmission speeds). Remove noise with components other than components. The switch 37 selectively supplies an output of one of the filters 34 and 35 having a frequency characteristic corresponding to the transmission rate detected by the transmission rate detection circuit 36 to the decoding processing circuit 38. Therefore, in this embodiment, even if the transmission speed changes,
It is possible to optimize the sensitivity of the light receiving element 31 and optimize the noise removal. However, in the present invention, the transmission rate detection circuit 36 is removed, and the load resistance control circuit 32 is replaced with a load resistance having a fixed resistance value.
Instead of the switch 37, a band-pass filter having a pass frequency band for passing both frequency components corresponding to the two transmission rates may be used.

As can be understood from the above description, the elements 30 to 37 in FIG. 2 receive the first optical signal transmitted from the first device 1 and encode the first optical signal by the encoding processing circuit 12 in FIG. It constitutes receiving means for demodulating the converted data.

Further, as shown in FIG. 2, the second device 2 performs remote control of the camera 10 (zoom of the camera 10, movement of the visual field, start / end of imaging, turning on / off of a wiper of the imaging window, etc.). , A data processing circuit 42 for converting a control signal from the remote control 41 into a predetermined data format, and performing modulation such as frequency modulation with a control signal output from the data processing circuit 42. Modulation circuit 43, a light emitting element 45 such as an LED, a driving circuit 44 for driving the light emitting element 45 according to the output of the modulation circuit 43, and an optical system for outputting the second optical signal emitted from the light emitting element 45 to the outside 46. The second optical signal includes the control signal. In addition,
Since the data amount of the control signal is very small, the transmission speed is fixed at a low speed.

Referring again to FIG. 1, the first device 1 comprises:
A light receiving element 17 such as a photodiode that receives the second optical signal transmitted from the second device 2, an optical system 16 that guides the second optical signal to the light receiving element 17,
Load resistor 18 for extracting the photoelectrically converted output of
And an amplifier circuit 19 for amplifying the extracted output, and FIG.
A demodulation circuit 20 that performs demodulation corresponding to the modulation performed by the inside modulation circuit 43, and a supporting device 2 that can change the direction of the camera 10 in response to the control signal demodulated by the demodulation circuit 20
4 and a control circuit 21 for controlling the zoom of the camera 10, the start / end of the imaging, and the ON / OFF of the wiper of the imaging window.

Further, the first device 1 controls the light receiving level of the second optical signal (that is, the light intensity of the second optical signal (particularly its carrier), and furthermore, the spatial transmission path) based on the output of the amplifier circuit 19. Light receiving level detecting circuit 2 for detecting the light transmittance)
2, and a light receiving level determining circuit 23 that determines whether or not the light receiving level exceeds a predetermined threshold based on a detection signal from the light receiving level detecting circuit 22. In order to prevent hunting, it is preferable to change the predetermined threshold value when the light receiving level of the second optical signal increases and decreases so that the hysteresis characteristic is obtained. If the transmission characteristics of the spatial transmission path are degraded due to weather conditions or the like, the light receiving level is reduced, and if the transmission characteristics of the spatial transmission path are good, the light receiving level is increased. The judgment result signal from the light reception level judgment circuit 23 is supplied to the encoding processing circuit 12 as described above, and when the light reception level is equal to or less than the threshold value, the encoding processing circuit 12 performs encoding at a predetermined low transfer rate. When the received light level is higher than the threshold value, encoded data is output at a predetermined high transfer rate as encoded data. In the present embodiment, the light receiving level detection circuit 22 and the camera 10
The elements 44 to 46 and 16 to 19, which also serve as a transmission device for transmitting the remote control signal, constitute detection means for detecting the state of the spatial transmission path.

According to the present embodiment, a moving image, which is a monitoring image captured by the camera 10 of the first device 1,
After being A / D converted by the / D conversion circuit 11, the data is coded by the coding processing circuit 12, and is directly modulated by the coded data to become a first optical signal, and the light emitting element 1
4 to the second device 2 in optical space transmission. The first optical signal is received by the light receiving element 31 of the second device 2, demodulated into coded data, decoded by the decoding processing circuit 38 into moving image data, and converted into a D / A conversion circuit. The video is converted into an analog video signal by 39 and the captured video is displayed on the monitor 40.

Regardless of whether or not a control signal is output from the remote controller 41, the second light emitting element 45 of the second device 2
(At least the carrier wave) is transmitted and received by the light receiving element 17 of the first device 1. This light receiving element 17
Is detected by the light receiving level detecting circuit 22.

If the light receiving level is low (that is, if weather conditions and the like are deteriorating), the transmission speed is reduced to a predetermined low speed by the encoding processing circuit 12 and is encoded with low quality to match the transmission speed. A low-quality moving image is displayed on the monitor 40. As described above, if the weather conditions are deteriorated, the transmission speed is reduced.
Since the photoelectric conversion efficiency of 4, 31 increases, transmission is hard to be interrupted. In this case, the quality of the moving image displayed on the monitor 40 is low. However, even if the quality is deteriorated, the moving image continues to be displayed on the monitor 40 and does not disappear at all. Can continue,
The merit is great.

On the other hand, if the light receiving level is high (that is, if the weather conditions and the like are good), the encoding processing circuit 12
As a result, the transmission speed becomes a predetermined high speed, and high-quality encoding is performed so as to match the transmission speed, and a high-quality moving image is displayed on the monitor 60.

As described above, according to the present embodiment, even if the weather conditions are deteriorated, the transmission is hard to be interrupted, and the monitoring of the captured moving image can be continued. In a good normal state, a moving image can be transmitted with high quality, and the captured moving image can be monitored with finer grain.

According to the present embodiment, the remote controller 4
By operating the camera 1, the user can remotely control the zoom of the camera 10, the movement of the visual field, and the like, which is convenient. The elements 16 to 19 and 44 to 46 in FIGS. 1 and 2 for realizing the remote control are also used as a part of the detecting means for detecting the state of the spatial transmission path. Compared to the case where the detection means is provided separately,
The structure is simple and inexpensive.

In the embodiments shown in FIGS. 1 and 2 described above, when remote control of the television camera 10 is not necessary, for example, the elements 20, 21, 24 in FIG. 1 and the elements in FIG. 41 to 43 may be removed.

In the embodiment shown in FIGS. 1 and 2 described above, if remote control of the television camera 10 is unnecessary, the television camera 10 may be modified as shown in FIGS. 3 and 4, for example. FIGS. 3 and 4 show another embodiment of the present invention. In FIGS. 3 and 4, the same or corresponding elements as those in FIGS. The description of the operation will be omitted.

The embodiment shown in FIGS. 3 and 4 is different from the embodiment shown in FIGS. 1 and 2 only in the points described below. That is, in the present embodiment, in the second device 2, the elements 41 to 46 in FIG. 1 are removed, and instead, the one of the first optical signals output from the light emitting element 14 of the first device 1 is changed. The light receiving element 1 of the first device 1
A mirror 50 for reflecting the light toward 7 is added. Further, in the present embodiment, in the first device 1, the elements 20, 21, and 24 in FIG. 1 are removed, and the light receiving element 17 of the first device 1 outputs the first light reflected by the mirror 50. A signal is received.

In the embodiment shown in FIGS. 3 and 4, FIG.
In addition, the elements 16 to 22 and 50 in FIG. 4 constitute detection means for detecting the state of the spatial transmission path, and the configuration is very simple.

Further, the embodiment shown in FIGS. 1 and 2 is modified to change the intensity of the first optical signal to the second device 2.
(The side of the receiving device that receives the moving image) may detect the state of the spatial transmission path of the first optical signal. Examples are shown in FIGS.

FIGS. 5 and 6 show still another embodiment of the present invention. In FIGS. 5 and 6, FIGS.
Elements that are the same as or correspond to the elements in them are given the same reference numerals,
The overlapping description is omitted.

The embodiment shown in FIGS. 5 and 6 differs from the embodiment shown in FIGS. 1 and 2 only in the points described below. That is, in the present embodiment, as shown in FIG. 5, a light receiving level detection circuit 22 for detecting the light receiving level of the second optical signal from the first device 1 (the side of the transmitting device transmitting the moving image) The light reception level determination circuit 23 for determining the light reception level is removed. Instead, as shown in FIG. 6, in the second device 2, a light receiving level detecting circuit 70 for detecting the light receiving level of the first optical signal (ie, the light intensity of the first optical signal) and the light receiving level thereof A light receiving level determining circuit 71 for determining the threshold value is added. In the present embodiment, the combining circuit 72 is added in the second device 2 as shown in FIG. 6, and the separating circuit 6 in the first device 1 as shown in FIG.
0 is added, whereby the determination result signal from the light reception level determination circuit 71 is included in the second optical signal and
After being transmitted to the side of the device 1, it is supplied to the encoding processing circuit 12. That is, the combining circuit 72
Multiplexes the determination result signal from the light reception level determination circuit 71 and the control signal of the remote controller 41 from the data processing circuit 42 by multiplexing, and supplies the combined signal to the modulation circuit 43. On the other hand, the separation circuit 60 separates the combined signal demodulated by the demodulation circuit 20 into a determination result signal from the light reception level determination circuit 71 and a control signal of the remote controller 41 from the data processing circuit 42. The control signal is supplied to the encoding processing circuit 12 and the separated control signal is supplied to the control circuit 21.
To supply.

The optical path of the first optical signal is the original signal space transmission path for transmitting the image signal. In the embodiment shown in FIGS. 1 and 2, the state of the optical path of the second optical signal is detected. As a result, the state of the signal space transmission path is indirectly detected as it were. On the other hand, in the embodiment shown in FIGS. 5 and 6, since the light receiving level of the first optical signal is detected,
This means that the state of the original signal space transmission path is directly detected. Therefore, in the present embodiment, the original state of the spatial transmission path can be detected with higher accuracy, which is preferable. Further, in the embodiment shown in FIGS. 1 and 2, in order to increase the detection accuracy of the state of the original signal space transmission line, the optical path of the second optical signal is arranged near the optical path of the first optical signal. Although it is necessary, there is no such restriction in the embodiment shown in FIGS.

In the embodiment shown in FIGS. 5 and 6, the detection signal of the light receiving level detecting circuit 70 is directly input to the synthesizing circuit 72, and the light receiving level judging circuit 71 is divided into the separating circuit 60 and the encoding processing circuit 12. And may be provided between them. In addition, the light receiving level of the first optical signal and the determination result do not need to also serve as an optical transmission circuit for transmitting a control signal of the remote controller 41. For example, another arbitrary transmission means (another optical space transmission device or an electromagnetic wave , Etc.).

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments.

For example, the information transmitted by the free-space optical transmission apparatus according to the present invention may be audio, or may be both moving images and audio. When transmitting a moving image and a sound simultaneously, both may be multiplexed on the transmitting side and separated on the receiving side by a known method.

[0063]

As described above, according to the present invention,
Transmission is difficult to be interrupted even if weather conditions etc. worsen, and
It is possible to provide an optical space transmission device capable of transmitting a moving image and a voice with high quality in a normal state, and an image monitoring device using the same.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing a first device constituting an image monitoring device according to a first embodiment of the present invention.

FIG. 2 is a schematic block diagram showing a second device constituting the image monitoring device according to the first embodiment of the present invention.

FIG. 3 is a schematic block diagram showing a first device constituting an image monitoring device according to a second embodiment of the present invention.

FIG. 4 is a schematic block diagram showing a second device constituting an image monitoring device according to a second embodiment of the present invention.

FIG. 5 is a schematic block diagram showing a first device constituting an image monitoring device according to a third embodiment of the present invention.

FIG. 6 is a schematic block diagram showing a second device constituting an image monitoring device according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st apparatus 2 2nd apparatus 10 Television camera 11 A / D conversion circuit 12 Encoding processing circuit 13,44 Drive circuit 14,45 Light emitting element 15,16,30,46 Optical system 17,31 Light receiving element 18 Load Resistance 19, 33 Amplification circuit 22, 70 Light reception level detection circuit 23, 71 Light reception level determination circuit 34, 35 Filter 36 Transmission speed detection circuit 37 Switch 38 Decoding processing circuit 39 D / A conversion circuit 40 Television monitor 41 Remote control 42 Data Processing circuit 43 Modulation circuit 50 Mirror 60 Separation circuit 72 Synthesis circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H04N 7/22 F term (Reference) 5C054 AA05 CA04 CC03 CG05 DA01 DA05 EA03 EG00 FA00 FF02 HA01 5C064 EA02 EA05 5K002 AA03 AA05 BA21 DA05 EA05 EA06 FA03 GA01 GA02 GA04

Claims (9)

[Claims] 1. An optical space transmission apparatus for transmitting information of at least one of a moving image and a sound, comprising: an encoding unit for performing an encoding process including a data compression process on the information; A transmitting device that transmits an optical signal modulated by encoded data; a receiving device that receives an optical signal transmitted from the transmitting device and demodulates the encoded data; A decoding unit that performs a decoding process including a data decompression process on the obtained data; and a detection unit that detects a state of a spatial transmission path of the optical signal. And the transmission unit performs transmission by the optical signal at a transmission speed adjusted according to a detection signal from the detection unit, and encodes the information with a quality corresponding to the transmission speed. Sea urchin, the optical atmospheric link system, characterized in that the actuation. 2. The transmitting means for transmitting a second optical signal from the receiving device to the transmitting device, and the light intensity of the second optical signal provided on the transmitting device. 2. The optical space transmission apparatus according to claim 1, further comprising: a light intensity detecting unit that performs the operation. 3. The detecting means includes: a reflecting means for reflecting a part of an optical signal transmitted by the transmitting means on the receiving device side; and a reflecting means provided on the transmitting device side for reflecting an optical signal reflected by the reflecting means. 2. The optical space transmission apparatus according to claim 1, further comprising light intensity detection means for detecting light intensity. 4. The optical space transmission apparatus according to claim 1, wherein said detecting means includes a light intensity detecting means provided on said receiving apparatus side for detecting the light intensity of said optical signal. 5. An image monitoring apparatus comprising: an imaging unit; a space optical transmission device for transmitting a moving image captured by the imaging unit; and a display unit for displaying a moving image transmitted by the space optical transmission device. In the optical space transmission device, the transmission device includes a transmission device, a reception device, and a detection unit, and the transmission device performs an encoding process including a data compression process on a moving image captured by the imaging unit. Encoding means for performing, and transmitting means for transmitting an optical signal modulated by data encoded by the encoding means, the receiving device receives the optical signal transmitted from the transmitting means, Receiving means for demodulating the encoded data, and decoding means for performing a decoding process including a data decompression process on the demodulated data, Detect the condition The encoding unit and the transmission unit perform transmission by the optical signal at a transmission rate adjusted according to a detection signal from the detection unit, and encode the moving image with a quality corresponding to the transmission rate. An image monitoring device, which operates. 6. The detecting means for transmitting a second optical signal from the receiving device to the transmitting device, and detecting the optical intensity of the second optical signal provided on the transmitting device. 6. The image monitoring apparatus according to claim 5, further comprising: a light intensity detecting unit that performs the operation. 7. The image monitoring apparatus according to claim 6, wherein the second optical signal includes a control signal for controlling the image pickup unit. 8. The detecting device, comprising: a reflecting device that reflects a part of an optical signal transmitted by the transmitting device on the receiving device side; and a reflecting signal device that is provided on the transmitting device side and reflected by the reflecting device. 6. The image monitoring apparatus according to claim 5, further comprising light intensity detecting means for detecting light intensity. 9. The image monitoring apparatus according to claim 5, wherein said detecting means includes a light intensity detecting means provided on said receiving device side for detecting a light intensity of said optical signal.