JPH03188786A - Optical transmission line for color video signal - Google Patents

Abstract

PURPOSE:To make the phase of optical signals sent in parallel coincident by providing a phase correction means varying an optical path length and correcting a propagation time of an optical signal in an optical transmission line sending an optical signal of a component color video signal is sent in parallel. CONSTITUTION:Phase correction sections 4R, 4G, 4B are optical transmission lines sending an optical signal to vary the propagation time of the passing optical signal thereby varying the propagation time of the passing optical signal. The control circuit 5 controls the phase correction sections 4R, 4G, 4B based on the phase difference information from a phase difference detection circuit 25. Then the optical length of the phase correction sections 4R, 4G, 4B is varied to adjust the propagation time of the optical signal passing through the phase correction sections 4R, 4G, 4B so that the phases of the component color video signals detected by the phase difference detection circuit 25 are made coincident. Thus, the phases of the component color video signals fed to a pickup signal processing section 23 are all made coincident.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an optical transmission line for color video signals that transmits optical signals of component color video signals in parallel via an optical cable.

B0 Summary of the Invention The present invention provides an optical transmission path for a color video signal that transmits optical signals of a component color video signal in parallel via an optical cable. By providing a phase correction means for correcting time, it is possible to match the phases of optical signals transmitted in parallel via an optical cable.

C8 Prior Art Some color television camera apparatuses used in, for example, high-definition television broadcasting are so-called separated type in which an imaging section and a signal processing section are configured separately.

In such a separate type color television camera device, for example, red (R), green (G)
), blue (B) component color video signal,
By transmitting the signals to the signal processing section in parallel through different transmission paths, a transmission band for each signal is ensured, signal deterioration is prevented, and image quality is maintained.

Conventionally, bundles of coaxial cables have been used for such transmission lines, but compared to such electrical transmission lines, they have superior features such as smaller size, wider bandwidth, and lower loss. The use of optical transmission lines has also been considered in recent years.

By the way, when component color video signals are transmitted in parallel through different transmission paths as described above, a time difference (phase difference) occurs in the transmission output due to differences in the characteristics and length of each transmission path. , color shift may occur in the image formed from the output signal of the signal processing section.

For this reason, in conventional transmission lines, the required length of cable for transmission time adjustment is added to the transmission line, or the transmission output of the leading phase is delayed using an electrical delay circuit, and the transmission is performed in parallel using the above transmission line. The phases of the transmitted outputs were matched before being processed by the signal processing section.

D1 Problems to be Solved by the Invention However, since the conventional color video signal transmission path corrects the phase difference of the transmission output using the method described above, it has the following drawbacks.

In other words, if the above-mentioned phase correction of the transmission output is performed by adding a cable for adjusting the transmission time to the transmission line, for example, there is a disadvantage that it is inconvenient because a large number of adjustment cables must be prepared. be.

Further, if phase correction is performed by electrically delaying the transmission output using a delay circuit, there are disadvantages in that, in addition to signal deterioration, the device becomes larger and power consumption increases.

In particular, optical transmission lines can have longer transmission distances than conventional transmission lines, and in that case, the phase difference between each transmission output also increases, so the above-mentioned drawbacks become a major problem.

Furthermore, since component color video signals used in high-definition television broadcasting have a wide band and high quality, if such signals are transmitted through conventional transmission lines, the quality of the video will be severely degraded. For this reason, there is a strong desire to put into practical use an optical transmission line that has features such as broadband and low loss as described above and can overcome the above-mentioned drawbacks.

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above circumstances, and provides an optical transmission line with a novel configuration that can match the phases of optical signals of component color video signals transmitted in parallel. It is an object.

80 Means for Solving the Problems In order to achieve the above-mentioned object, an optical transmission line for color video signals according to the present invention is an optical transmission line for transmitting optical signals of component color video signals in parallel via an optical cable. Further, a phase correction means for correcting the propagation time of the optical signal by varying the optical path length is provided.

F0 effect In the optical transmission line for color video signals according to the present invention, by varying the optical path length with the phase correction means provided in the optical transmission line, the propagation time when the optical signal passes through this phase correction means can be adjusted. to correct the propagation time of the optical signal of the component color video signal transmitted in parallel via the optical cable.

G. Embodiments Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an optical transmission line 1 of this embodiment.

The optical transmission II of this embodiment includes an imaging unit 10 that images a subject.
and a signal processing section 20 that performs signal processing on the component color video signal formed by the imaging section 10. The optical signal of the video signal is transmitted in parallel to the signal processing section 20.

The imaging unit 10 of the imaging device 100 uses a prism 12 to pass imaging light provided through a lens 11 into red (R) and green (G).
) and blue (B), and the imaging light of these three primary colors is imaged by solid-state imaging devices 13R, 13G, and 13B, such as CCDs, respectively, to form component color video signals of the three primary colors. These solid-state image sensors 13R, 13G
, 13B are converted into optical signals by electro-optical conversion elements 14R, 14G, 14B, respectively, and optical connectors 15R, 515G,
15B to the optical transmission line 1 of this embodiment.

The optical transmission line 1 transmits optical signals of component video signals outputted from the imaging section 10 via the respective optical connectors 15R, 15G, and 15B to an optical cable 2R.
, 2G, 2B and the phase correction sections 4R, 4G, 4B, the optical connectors 21R, 21G, 2 of the signal processing section 20
Transmits up to 1B in parallel. The above optical cables 2R, 2G,
2B is connected to the phase correction units 4R, 4G, and 4B via optical connectors 3R, 3G, and 3B, and if these optical cables 2R, 2G, and 2B have different lengths and characteristics, they will not be transmitted in parallel. As described above, a phase shift occurs between the optical signals.

Each of the phase correction units 4R, 4G, and 4B is an optical transmission line that transmits the optical signals supplied from each of the optical cables 2R, 2G, and 2B, and the length of the optical path is variable.

By changing the optical path length of the phase correction sections 4R, 4G, and 4B, each of the phase correction sections 4R, 4G, and 4B can be
The propagation time of an optical signal passing through can be varied. Therefore, by changing the optical path length, it is possible to advance or delay the phase of the optical signal transmitted through the optical transmission line 1. These phase correction parts 4R
, 4G, and 4B are each supplied with a control signal from the control circuit 5 for variably controlling the optical path length.

Note that these phase correction units 4R, 4G, 4B and the control circuit 5
Since it can be separated from the optical cables 2R, 2G, 2B by the optical connectors 3R, 3G, 3B, it may be provided in the same housing as the signal processing section 20, which will be described next.

Each optical signal outputted from each of the phase correction sections 4R, 4G, and 4B and given to the signal processing section 20 via each of the optical connectors 21R, 21G, and 21B is transmitted to the photoelectric conversion element 22R,
22G and 22B, respectively. The optical signal supplied to the signal processing section 20 is transmitted to each of the photoelectric conversion elements 22R.
.
from there to an external device such as a video tape recorder.

Further, the component color video signals output from the photoelectric conversion elements 22R, 22G, and 22B are supplied to a phase difference detection circuit 25. This phase difference detection circuit 25 is
The phase difference between the component color video signals provided from the photoelectric conversion elements 22R122G and 22B to the image pickup signal processing section 23 is detected to form phase difference information.

Here, in order to detect the phase difference between such component color video signals, for example, the arrival time difference of synchronization pulses (SYNC) included in each signal may be detected by electrical signal processing. Note that from each electro-optical conversion element 14R, 14G, 14B of the imager section 10,
By making it possible to send a pseudo synchronization pulse (SYNC) optical signal, it is possible to detect a phase difference even when the imaging section 10 is not imaging a subject.

The phase difference information obtained by the phase difference detection by the phase difference detection circuit 25 is sent to the control circuit of the optical transmission line 1 via the terminal 26.
sent to. This control circuit 5 includes the phase difference detection circuit 2
Based on the phase difference information from 5, the phase correction section 4R, 4
G and 4B to vary the optical path lengths of the phase correction sections 4R, 4G, and 4B so that the phases of the component color video signals detected by the phase difference detection circuit 25 coincide with each other. The propagation time of the optical signal passing through the sections 4R, 4G, and 4B is adjusted.

In this way, by varying the optical path length of each phase correction section 4R, 4G, 4B and adjusting the propagation time of the optical signal passing through these phase correction sections 4R, 404B, the optical cables 3R, 3G, 3B, etc. The difference in propagation time that occurs between the optical signals can be corrected by each of the phase correction sections 4R, 4G, and 4B.

Therefore, this optical transmission line 1 includes each phase correction section 4R.
, 4G, and 4B, the propagation time of the optical signal transmitted through the optical transmission line 1 is corrected, and the phase of the component color video signal supplied to the image pickup signal processing section 23 is all adjusted. Can be matched. Therefore, the imaging signal processing section 23 can perform signal processing on the phase-matched component video signals, so that the output terminal 24 can obtain an output video signal in which three primary color images are overlapped. .

Conventionally, when electrically matching the phases of signals, the signal with the leading phase was delayed and the phase of other signals was matched to the signal with the most delayed phase, but this optical transmission line 1, the phase of the optical signal can be changed in both leading and delayed directions by varying the optical path length of each of the phase correcting sections 4R, 4G, and 4B. Even if the phase difference correction width is not so wide, it is possible to widen the overall correction width. Moreover, each of the above-mentioned phase correction sections 4R.

Since 4G and 4B can change the phase of the optical signal in both the lead and lag directions, these phase correction units 4R, 4G, and 4
The optical path length of one of B may be fixed.

FIG. 2 shows an example of the configuration of each of the phase correction sections 4R, 4G, and 4B.

The phase correction section 40 shown in FIG.
a, 41b, 41c, 41d, 41e.

It is configured by combining mirrors 41f, 41g, and 41h, and these mirrors 41a, 41b, 4Ic, and 41d
, 41e, 41F, 41g, 41h, these mirrors 41a, 41b, 41
c, 41d, 41e.

The optical path length is varied by changing the optical path of the optical signal reflected by 41f, 41g, and 41h.

For example, the phase correction section 40 includes the optical cable 2R.
The optical signal transmitted to the optical connector 3R is supplied through the optical connector 3R. This optical signal is guided from the optical connector 3R to the pre-input cable 42, and then guided to the first mirror 41a via the collimator lens 43, as shown by the broken line in FIG. This optical signal is guided from the first mirror 41a to the second mirror 41b, and then passes through the second to fifth mirrors 4.
After being repeatedly reflected between 1b, 41c, 41d, and 41e, the light is guided from the second mirror 41b to the eighth mirror 41h via the seventh mirrors 41f and 41g. This optical signal is guided from the eighth mirror 41g via the collimator lens 44 to the light output cable 45, and is sent to the charging conversion element 22R via the optical connector 21R.

The optical path control unit 46 is connected to the control circuit 5 via a terminal 47.
A control signal is given from This optical path system i11 section 46
In response to a control signal from the control circuit 5, a drive device 48 made of a motor or the like is operated to move the first mirror 41a in the direction of the optical axis of the first coupler 42 (in the direction of the arrow).

By moving the first mirror 41a, the optical path of the optical signal guided to the phase corrector 40 changes. Therefore, the optical path control section 4G controls the first mirror 41a.
Simultaneously with the movement of the driving device 49, a driving device 49 having the same structure as the driving device 49 is operated, and the eighth mirror 41h is moved to move the light of the light output cable 45 so that the optical signal is guided to the light output cable 45. Move it in the axial direction (direction of arrow B).

For example, when the position of the first mirror 41a is moved a predetermined distance in the direction AI away from the first inlet cable 42 from the position shown in FIG. 2, and the state shown in FIG. The optical paths of the mirrors 41b, 41c, 41d, and
Since the number of times the optical signal is reflected at 41e is reduced, the optical path length is shortened.

In this way, in this phase correction section 40, the control circuit 5
According to the control signal from the first. Eighth mirror 41
By moving a and 41h and changing the optical path of the optical signal, the optical path length is varied and the propagation time of the optical signal passing through it is changed.

Further, in this phase correction section 40, the propagation time of the optical signal can be adjusted by the refractive index of the substance that forms the optical path of the optical signal. That is, for example, if the optical path of the phase correction section 40 is provided in a material with a high refractive index, the propagation time of the optical signal will become longer, so it is possible to increase the phase correction amount or shorten the optical path length. I can do it. In addition, each of the mirrors 41b, 41c, 41d is placed in a transparent solid material such as a glass material.
.

If mirrors 41e, 41f, and 41g are arranged, these mirrors 41b, 41c, 41d, and 41e.

In addition to facilitating the positioning of mirrors 41f and 41g, these mirrors 41b, 41c, 41d, and 41e
, 41f, and 41g are stably maintained, the earthquake resistance and strength are improved, and the characteristics are stabilized.

FIG. 4 shows another example of the configuration of the phase correction sections 4R, 4G, and 4B.

The phase correction unit 50 shown in FIG. 4 guides an optical signal into a polygonal mirror 51, which has a transparent polygonal inner wall surface shaped like a polygonal mirror, and guides the optical signal at an incident angle By changing , the optical path of the optical signal is changed and the optical path length is varied.

For example, the optical signal transmitted via the optical connector 3R is transmitted from the pre-coupled cable 52 via the collimator lens 53 to the optical window 5 formed on a predetermined surface of the polygonal mirror 51.
1a to the inside of the polygonal mirror 51. The optical signal guided to the polygonal mirror 51 is repeatedly reflected inside the polygonal mirror 51, as shown by the broken line in FIG.
led to the outside of The optical signal guided to the outside from this polygonal mirror 51 is guided to the light output capule 55 via the collimator lens 54, and is sent from the light output capule 55 to the photoelectric conversion element 22R via the optical connector 21R. .

The optical path control unit 56 is connected to the control circuit 5 via a terminal 57.
A control signal is given from This optical path control section 56 is
In response to a control signal from the control circuit 5, a drive device 58 consisting of a motor or the like is operated, and the polygonal mirror 51 is
The pre-incident capillary 52 and the collimator lens 5 are centered at point 0 on the optical window 51a, where the optical paths of the incident light and the outgoing light intersect, so that the incident angle of the optical signal changes.
Move the position with 3. By changing the angle of incidence of the optical signal on the polygonal mirror 51, for example, the fifth
As shown by the broken line in the figure, the optical path of the optical signal guided to the phase corrector 50 changes, and the optical path length is varied. Also,
Since the output angle of the optical signal from the polygonal mirror 51 also changes, the optical path control section 56 controls the input optical cable 5.
At the same time as the drive device 58 is moved, a drive device 59 configured similarly to the drive device 58 is operated, and the light output cable 55
and the collimator lens 54.

In this manner, the phase correction section 50 changes the optical path within the polygon mirror 51 by changing the incident angle of the optical signal guided to the polygon mirror 51 in accordance with the control signal from the control circuit 5. The optical path length can be varied by changing the
Adjust the propagation time of the optical signal passing through it.

Further, in this phase correction section 50, the polygonal mirror 51
By adjusting the internal refractive index, the variable range of the optical signal propagation time can be made as desired. Also,
By using the polygonal mirror 51 in which the inner wall surface of the transparent polygon is shaped like a mirror, the phase correction unit 50 can stably maintain the relative positions of the mirrors, thereby making it possible to stabilize the characteristics.

FIG. 6 shows still another example of the configuration of the phase correction sections 4R, 4G, and 4B.

The phase correction unit 60 shown in FIG. 6 connects the optical transmission path through which the optical signal is transmitted to the optical switches Sla and S2a.

The optical path length is made variable by switching between S3a, Slb, S2b, and S3b.

For example, the optical signal transmitted via the optical connector 3R is guided from the pre-input cable 61 to the optical switch S18. This optical switch Sla includes an optical delay cable Kl, an optical switch 32a, and an optical delay cable 2. Optical switch S3a
, 3 to the optical delay cable, 4 to the optical switch S3b, and the optical delay cable. 5. Optical switch S2b and optical delay cable. It is connected to the optical connector 21R via the optical switch Slb and the light output cable 62 in this order. Further, the optical switch Sla is connected to the optical switch Sl via an optical cable 63.
connected to b. Similarly, the optical switch S2a is connected to the optical switch S2b via an optical cable 64. Further, the optical switch S3a is connected to the optical cable 6.
5 to the optical switch S3b.

Each of the above optical switches Sla, S2a, S3a, Slb, S
2b and S3b, the connection operation of each cable is controlled by an optical switch control section 67. This light switch control section 67
A control signal from the control circuit 5 is applied to the terminal 66 through the terminal 66.

The phase correction unit 60 controls each of the optical switches Sla and S2 based on the control signal output from the control circuit 5.
By controlling the optical cable connection operations of a, S3a, Slb, S2b, and S3b by the optical switch control section 67, the optical path length can be varied as follows.

That is, the optical signal led from the input cable 61 is transmitted to the optical output cable 62 via the optical cable 63.
When the optical switch control section 67 controls the optical switch Sla and the optical switch Slb, the optical path length of the optical signal becomes the shortest.

Further, the optical signal guided from the pre-input cable 61 is transmitted to the optical delay cable Kl, the optical cable 64. so as to be guided to the optical output cable 62 via the optical delay cable 5,
The optical switch control section 67 controls each optical switch Sla,
When Slb, S2a, and S2b are controlled, the optical path length of the optical signal becomes longer than in the above case.

Further, the optical signal led from the pre-input cable 61 is sent to the optical delay cable Kl, and the optical delay cable 65 is connected to the optical delay cable 65.
．． 4. Optical delay cable. The optical switch control unit 67 controls each of the optical switches Sla, Slb, and S2 so that the optical delay cable 5 leads to the optical output cable 62.
a, S2b.

When S3a and S3b are controlled, the optical path length of the optical signal becomes even longer than in the above case.

Further, the optical signal guided from the pre-input cable 61 is sent to the optical delay cable Kl, 2° to the optical delay cable 3. 4. Optical delay cable. The optical switch controller 67 controls each of the optical switches Sla and Slb so that the optical delay cable 5 leads to the optical output cable 62.
, S2a, 32b, S3a, and S3b,
The optical path length of the optical signal is the longest.

2. To each of the above optical delay cables Kl. 3. 4°K5 is a predetermined length so that the propagation time of the optical signal is as desired. In addition, these optical delay cables K1.
2. 3. 4. 5. By changing the refractive index of the optical delay cables Kl and slowing down the propagation speed of the optical signal, the optical delay cables Kl and K3. 4. 5 can be shortened, thereby making it possible to downsize this phase correction section 60.

In this way, in this phase correction section 60, the control circuit 5
Based on the control signal output from the optical switches Sla, Sob, S2a, and S2b.

By controlling S3a and S3b, the optical delay cable Kl, through which the optical signal is transmitted, 2. 3. 4 and 5 to vary the optical path length and adjust the propagation time of the optical signal passing through.

Note that each optical switch Sla of such a phase correction unit 60
, Slb, S2a, S2b, S3a, S3b and each optical cable Kl, 2. 3. 4. 5.61, 62.63 to
, 64, 65 can also be integrally formed using a three-dimensional optical waveguide.

By integrally forming the phase correction section 60 with the optical three-dimensional waveguide in this way, the optical switches SIa, Slb
, S2a, S2b, S3a, and S3b, the optical path can be reliably selected, and the characteristics can be stabilized and productivity can be improved.

In this embodiment, the optical transmission path l for color video signals according to the present invention is applied to an imaging apparatus 100 that transmits optical signals of component video signals of three primary colors from the imaging section 10 to the signal processing section 20. I explained about
Of course, the optical transmission line according to the present invention can be applied to devices other than the imaging device 100 as long as they transmit optical signals of component video signals.

Furthermore, in this embodiment, the control circuit 5 controls the propagation time of each optical signal propagating through the optical transmission path l, depending on the phase difference of the component video signals detected by the phase difference detection circuit 25. However, the user may determine the phase difference and manually control the propagation time.

Further, each of the phase correction sections 4R, 4G, and 4B may be configured by combining the various methods described above.

Furthermore, by combining the phase difference correction by each of the phase correction units 4R, 4G, and 4B with other optical or electrical phase difference correction, the phase correction width of the component color video signal can be widened. Accuracy can be improved.

Furthermore, in this embodiment, each of the optical cables 2R, 2
The above-mentioned phase correction sections 4R are provided after G and 2B.

4G and 4B, but for example, each of the above optical cables 2R,
Each phase correction section 4R is provided before 2G and 2B.

It is also possible to provide 4G and 4B.

Further, in this embodiment, component color video signals of three primary colors were optically transmitted, but for example, luminance signals (
The optical transmission line according to the present invention can also be used for optical transmission of component color video signals such as color signals (Y) and color signals (C).

H0 Effects of the Invention In the optical transmission line for color video signals according to the present invention, by varying the optical path length of the phase correction means provided in the optical transmission line, the propagation time when the optical signal passes through the phase correction means can be changed. is adjusted to compensate for the optical signal propagation time of the component color video signals transmitted in parallel via the optical cable.

Therefore, in the optical transmission path for color video signals to which the present invention is applied, the phase of each optical signal transmitted in parallel through the optical transmission path can be corrected by the phase correction means.

Therefore, the optical transmission line for color video signals to which the present invention is applied can prevent phase shifts from occurring in the optical signals of component color video signals transmitted in parallel.

Furthermore, if the optical transmission line according to the present invention is used to transmit color video signals used for high-definition television broadcasting, etc., wideband, high-quality component color video signals can be transmitted with almost no deterioration. , it is possible to maintain sufficient image quality.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an optical transmission line according to the present invention. FIGS. 2 to 6 are schematic diagrams showing configuration examples of the phase correction section used in the above embodiment. Of these, Figures 2 and 3 use a large number of mirrors, Figures 4 and 5 use a polygonal mirror with a transparent polygonal inner wall configured in a mirror shape, and Figure 6 The optical path is changed using an optical switch. 1... Optical transmission line 2R, 2G, 2B... Optical cable 4R, 4G, 4B, 40, 50.60... Phase correction section 5... Control circuit 10... Imaging section 14R, 14G, 14B ...Lightning conversion element 20...
Signal processing units 22R, 22G, 22B... photoelectric conversion element 23...
Imaging signal processing unit 100...imaging device

Claims (1)

[Claims] An optical transmission line for color video signals, which is provided with a phase correction means for correcting the propagation time of the optical signals by varying the optical path length, in the optical transmission line for transmitting the optical signals of the component color video signals in parallel via an optical cable. .