JP2002101044A - Light signal transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light signal transmitter, which can accurately extract original pulse row light signal from a multiplexed pulse row light signal, and can transfer the pulse row light signal between many terminals with high transmission quality. SOLUTION: The length of the transmission path, composed of an optical fiber and a light mixer 34, the composition of the quality of optical fibers 30, 32, and 36 and the light mixer 34, the optical wavelength of the light signal emitted from light emitters 221 and 222, and further the light intensity level of the pulse row light signal having entered each sending node 241 and 242 are adjusted, so that each light intensity level that the multiplexed pulse row light signal received with a light signal receiver has is not less than each threshold voltage which is set for every light intensity level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical signal transmission device, and more particularly, to an optical signal transmission apparatus which transmits a plurality of pulse train optical signals as a multiplexed pulse train optical signal and superimposes the original pulse train optical signal from the received multiplex pulse train optical signal. The present invention relates to an optical signal transmission device that extracts and outputs the extracted signal to the outside.

[0002]

2. Description of the Related Art As an optical signal transmission apparatus for performing multiplex transmission using a plurality of light intensities, for example, Japanese Patent Application Laid-Open No. 11-1960
No. 69 proposes an optical signal transmission device that can connect a large number of terminals (devices, circuit boards, and the like) and that can freely communicate with a plurality of terminals.

This optical signal transmission apparatus generates pulse train optical signals having different light intensity levels among a plurality of optical signal transmission units, outputs the pulse train optical signals to an optical transmission medium, and transmits the optical signal through the optical transmission medium.
The optical signal receiving unit extracts and identifies a pulse train optical signal for each light intensity level.

[0004] For example, there are provided two optical signal transmitting sections, a first optical signal transmitting section and a second optical signal transmitting section, wherein the first optical signal transmitting section outputs a signal having an optical intensity of 1, The case where the optical signal transmitting section outputs a signal of optical intensity 2 will be described.

A first optical signal transmitting section outputs a pulse train optical signal to an optical transmission medium at an on / off timing as shown in FIG. 10 (A), and a second optical signal transmitting section as shown in FIG. 10 (B). The pulse train optical signal is output to the optical transmission medium at an appropriate on / off timing. In the optical transmission medium, the signal of the signal and the optical intensity V ₂ of the light intensity V ₁ is inputted, as shown in FIG. 10 (C), the light intensity when the output of the on-pulse train optical signal overlaps the signal of the optical intensity V ₃ are added. Note that in FIG. 10, the light intensity of the optical signal is represented by a voltage value (V ₀ , V ₁ , V ₂ ,
V ₃ ; Here, it is assumed that V ₂ = 2V ₁ and V ₃ = 3V ₁ . FIG. 7 is a waveform diagram represented by converting the values in FIG.

Accordingly, the optical signal receiving section receives the pulse train optical signal transmitted through the optical transmission medium and detects the output level of the pulse train optical signal at each sampling timing (for example, t1 to t9 in FIG. 10). and, a threshold level set in the light intensity levels for each of the optical signals (e.g., in V _1, any level between V ₁ and V _2, the V _2, any between V ₂ and V ₃ level, the V _3, in correspondence with V ₃ or more arbitrary level, etc.) the received multiplexed pulse train optical signal from the first optical signal transmitting unit is output by the pulse train optical signal and second optical signal transmitting unit output The extracted pulse train optical signal is extracted and output to the outside.

[0007]

In the optical signal transmission apparatus having the above-described structure, a part of the pulse train optical signal is absorbed by a light guide path or the like during propagation of the pulse train optical signal, and a loss (absorption loss) occurs. The amount of absorption loss increases as the length of the light guide path increases, and decreases as the length of the light guide path decreases. Therefore, the amount of absorption loss of the pulse train optical signals emitted from the plurality of optical signal transmitters differs depending on the length of the light guide path that propagates.

In an optical signal transmission device having a plurality of optical signal transmitting units, the distances from all the optical signal transmitting units to the optical signal receiving units cannot always be completely equalized. The amount of absorption loss of the pulse train optical signal received by the unit varies.

For example, in the case of an optical signal transmission device having the above-described two optical signal transmission units, if the absorption loss of one pulse train optical signal is extremely large, as shown in FIG. There is a problem that the intensity level of the pulse train optical signal when the optical signals overlap is lower than a specified threshold level, and is erroneously recognized as one signal. Note that this light intensity loss depends on the shape of the light guide path,
The same also occurs due to differences in transmission efficiency due to differences in the composition of the material constituting the light guide path and the optical wavelength of the pulse train optical signal.

Further, when the length of the light guide path is different, the propagation time of the pulse train optical signal is different, so that the timing at which the pulse train optical signal enters the optical signal receiving unit is shifted. Therefore, as shown in FIG. 11B, when the two signals are superimposed, the rising position and the falling position of the light intensity level of each pulse train optical signal are shifted, and the value of the added light intensity is As a result, the value detected at the sampling timing (t1 to t9 in FIG. 11) changes. As a result, there is a problem that it is difficult to accurately extract the original pulse train optical signal from the superimposed multiplex pulse train optical signal.

[0011] Due to these problems, the conventional optical signal transmission device as described above has a problem that it is difficult to realize stable identification and maintain transmission quality.

From the above, it is an object of the present invention to accurately extract an original pulse train optical signal from a superimposed multiplex pulse train optical signal and to transfer a pulse train optical signal between many terminals with high transmission quality. It is an object of the present invention to provide an optical signal transmission device capable of performing the following.

[0013]

In order to solve the above-mentioned problems, an optical signal transmission apparatus according to the first aspect of the present invention provides a plurality of optical signals for generating and transmitting pulse train optical signals having different light intensity levels. An optical transmission system comprising: a transmitting unit, and a light guide path for transmitting a multiplexed pulse train optical signal in which a plurality of pulse train optical signals transmitted from each of the plurality of optical signal transmitting units are incident and in which the plurality of pulse train optical signals are mixed. Means,
Receiving means for receiving the multiplexed pulse train optical signal transmitted by the optical transmission means; and determining from the multiplexed pulse train optical signal received by the receiving means the light intensity of the plurality of pulse train optical signals and the number of the pulse train optical signals. Optical signal extracting means for extracting pulse train optical signals individually emitted by the plurality of optical signal transmitting means in accordance with the threshold level to be obtained, and the light intensity of the plurality of pulse train optical signals reaching the receiving means. The coupling efficiency of each of the plurality of optical signal transmitting means and the optical transmitting means, and the light, so that the level is a light intensity level equal to or higher than a threshold level determined corresponding to each individual pulse train optical signal. Coupling efficiency between the transmission means and the reception means, the length of the light guide path, the shape of the light guide path, the composition of the material of the light guide path, the optical wavelength of the pulse train optical signal, and the optical signal At least one of the emission intensity level of the transmission means has been characterized in that it is adjusted.

In the optical signal transmission device according to the present invention, the pulse train optical signals having different light intensities generated by the plurality of optical signal transmission means are made incident on the light guide path of the optical transmission means, and inputted into the light guide path. A plurality of pulse train optical signals are transmitted as a superposed multiplex pulse train optical signal.

[0015] The receiving means receives the multiplexed pulse train optical signal transmitted by the optical transmission means, and the optical signal extracting means calculates the superposed pulse train optical signal from the multiplexed pulse train optical signal received by the receiving means. Are extracted respectively. This extraction is based on the light intensity level of the superimposed pulse train optical signal and the threshold level determined according to the number of the pulse train optical signals, and a pulse in which the ON outputs of a plurality of signals are superimposed on and above the threshold level This is performed by determining whether the pulse is an ON output pulse of one signal.
Note that the threshold level is determined based on the light intensity level of the optical signal output from the optical signal transmitting means and the light intensity level of the pulse in which the ON outputs of a plurality of signals are superimposed.

For example, based on a multiplexed pulse train optical signal in which a first optical signal having an optical intensity level of A (where A is an arbitrary number) and a second optical signal having an optical intensity level of 2A are superposed, the original optical signal is obtained. When extracting the first optical signal and the second optical signal, which are signals, the first threshold level for extracting the first optical signal is set to a half of the light intensity level of the first optical signal. 0.5A, and the second threshold level for extracting the second optical signal is between the optical intensity level A of the first optical signal and the optical intensity level 2A of the second optical signal, and The level is 1.5 A, which is the same level as the two light intensity levels, and is the first level.
The third threshold level for extracting the multiplexed light of the first optical signal and the second optical signal is defined by the light intensity level of the first optical signal and the second threshold level.
Light intensity level 3A obtained by adding the light intensity level of the optical signal of FIG.
And the light intensity level 2A of the second optical signal and the same level separated as the two light intensity levels, 2.5
A and so on.

In the optical signal transmission apparatus according to the present invention, the light intensity levels of the plurality of pulse train optical signals reaching the receiving means are equal to or higher than a threshold level determined for each individual pulse train optical signal. Level, the coupling efficiency of each of the plurality of optical signal transmitting units and the optical transmitting unit, the coupling efficiency of the optical transmitting unit and the receiving unit, the length of the light guide, and the shape of the light guide. At least one of a composition of a material of the light guide, an optical wavelength of the pulse train optical signal, and a light emission intensity level of the optical signal transmitting means is adjusted.

For example, the length of the light guide path of the optical transmission means may be shortened to reduce the amount of absorption loss, and the light intensity level of each of a plurality of pulse train optical signals may not be reduced so much.

With this configuration, even if a part of the optical signal is absorbed during the propagation of the pulse train optical signal and a light amount loss occurs, the pulse train optical signal corresponding to each threshold level is obtained by the optical signal extracting means. Can be reliably detected. Therefore, the pulse train optical signal can be accurately extracted by the optical signal extracting means.

Preferably, the light intensity levels of the plurality of pulse train optical signals are set so as to satisfy a direct proportional relationship. In this case, the threshold level set for each pulse train optical signal and the threshold level set for each of the plurality of light intensity levels included in the multiplexed pulse train signal when each pulse train optical signal is superimposed are each one step lower. The difference from the threshold level and the difference from the next higher threshold level may be set to be constant.

For example, at least one of the length, shape, material composition, and optical wavelength of the optical signal from the optical signal transmitting means is made equal to the light guide path of the optical transmission means, and the light of each of the plurality of pulse train optical signals is made equal. A first coupling efficiency between the optical signal transmitting unit and the optical transmitting unit for each of the plurality of optical signal transmitting units, the optical transmitting unit, and the receiving unit; A total coupling efficiency obtained by adding the second coupling efficiencies of the optical transmission means and the receiving means is equalized, and the light quantity loss due to the coupling efficiencies of the respective light intensity levels of the plurality of pulse train optical signals is made uniform. And so on.

By setting in this way, it is possible to prevent the threshold levels from being set partially close to each other, thereby preventing erroneous extraction of the pulse train optical signal between the threshold levels set close to each other. As a result, the pulse train optical signal can be extracted more accurately.

According to a second aspect of the present invention, in the optical signal transmission apparatus according to the first aspect, the threshold level is set to a value corresponding to the first one of the light intensity components of the multiplex pulse train optical signal received by the receiving means. The light intensity level is set at an intermediate value between one light intensity level and a second light intensity level one step lower or one step higher than the light intensity level.

According to the second aspect of the present invention, the first threshold value is set at an intermediate level between the first light intensity level and the second light intensity level one step lower or one step higher than the first light intensity level. When the pulse train optical signal of the light intensity level is extracted, it is possible to prevent the pulse train signal of the second light intensity level from being erroneously detected.

The threshold levels are the first light intensity level and the second light intensity level.
Are located at the same light intensity level separated from both of the light intensity levels, and are too close to either one of the first light intensity level and the second light intensity level, and The possibility that the pulse train optical signal is erroneously extracted can be reduced.

Further, when the length of the light guide path is different, the propagation time of the pulse train optical signal is also different, so that the timing at which the pulse train optical signal enters the receiving means is shifted. Therefore, claim 3
In the invention according to claim 4, the length of the light guide path and the optical signal are adjusted so that the shift amount of the incident timing of the plurality of pulse train optical signals incident on the receiving means falls within a predetermined range. At least one of the output timings of the pulse train optical signal transmitted by the transmission means is controlled. It should be noted that the predetermined range is a range in which the amount of deviation is allowable, and preferably, as described in claim 5, the unit pulse width is determined in advance from the rising timing of the previously input pulse train optical signal. It is better to be within the range between the timings defined in the above.

Accordingly, even when the rising position and the falling position of the light intensity level of each pulse train optical signal are shifted when a plurality of signals are superimposed, the overlapping portion is sampled at the sampling timing of the pulse train optical signal. Therefore, it is possible to accurately extract the superposed pulse train optical signal.

The optical transmission means may include a diffusion optical system for diffusing the light from the optical signal transmission means, and a light diffused by the diffusion optical system for receiving the light. And a sheet-shaped optical transmission medium that propagates through the light guide path formed in the optical path.

As such a sheet-shaped optical transmission medium, for example, an optical transmission layer composed of a material that propagates light and a cladding layer having a low refractive index lower than the refractive index of the optical transmission layer are alternately laminated. The sheet-shaped transmission medium having the above configuration can be applied.

By using such a sheet-shaped optical transmission medium, optical signals can be superimposed relatively easily. In addition, since the optical transmission medium means is sheet-shaped, when mechanically connecting to the optical signal transmitting means and when mechanically connecting to the receiving means, high-precision optical alignment is not required, An optical signal transmission device that has good assembly efficiency and can be manufactured at low cost can be provided.

Further, since the optical positioning is not required, the mounting positions of the members such as the optical signal transmitting means and the receiving means can be freely changed, so that a highly expandable and highly flexible system can be constructed. There is also an advantage that.

Since the optical transmission means has a diffusion optical system, the spread angle of the emitted optical signal is widened,
Since the optical signal is propagated over a wide range, it is possible to provide more receiving means for receiving the signal light, which is preferable. As such a diffusion optical system, for example,
A diffusion member such as a diffusion plate, a diffusion lens member, or a combination lens member having a combination of a plurality of lens members and having an optical characteristic of diffusing incident signal light can be applied.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An optical signal transmission apparatus according to a first embodiment of the present invention transmits pulse train optical signals having different light intensity levels as shown in FIG. The two transmitting units (the first transmitting unit 10 ₁ and the second transmitting unit 10 ₂ ) are transmitted by the optical transmitting unit 14 that transmits the pulse train optical signal transmitted from each of the two transmitting units, and the optical transmitting unit 14. And a receiving unit 12 for receiving the pulse train optical signal.

The first transmission unit 10 _1, the transmission circuit 20 ₁ includes a light emitter 22 ₁ and the transmission node 24 _1, and generates a pulse train electrical signal based on the transmitting circuit 20 ₁ is input from the outside, respectively data and outputs to the light emitting device 22 _1. Light emitter 2
2 ₁ emits light based on the pulse train electrical signals generated by the transmitting circuit 20 _1. Thus, the pulse train optical signal corresponding to the pulse train electric signal input from the outside is transmitted from the first transmitting portion 10 ₁ through the transmission node 24 _1. Note that the second transmission unit 10 _2, because first the same configuration as the transmission unit 10 _1, the description of those substantially the same reference numerals will be omitted. The first transmission unit 10 ₁ and the second transmission unit 10 _2, and is configured to output a pulse train optical signals of different light intensity levels with each other.

The optical transmission section 14 includes a first optical fiber 30, a second optical fiber 32, an optical mixing section 34, and a third optical fiber 36.

The first optical fiber 30 has a first transmitting unit 10 _1.
It emitted by, transmitting a first pulse train optical signal transmitted through the first transmission node 24 _1, the second optical fiber 32
It is emitted by the second transmission unit 10 _2, and transmits a second pulse train optical signal transmitted through the second transmission node 24 _2.

The light mixing unit 34 generates a first pulse train optical signal and mixing multiple pulse train optical signal and a second pulse train optical signal transmitted by the second transmission unit 10 _2, which is transmitted by the first optical fiber 30 . The multiplex pulse train optical signal has a light intensity level in which the light intensity levels of the first pulse train optical signal and the second pulse train optical signal are mixed. The third optical fiber 36 transmits the multiplex pulse train signal generated by the optical mixing unit 34.

The receiving section 12 includes a receiving node 26, a light receiver 2
7 and a receiving circuit 28. The light receiver 27 corresponds to the receiving means of the present invention, and the receiving circuit corresponds to the optical signal extracting means of the present invention. The receiving node 26 receives the multiplexed pulse train optical signal transmitted by the third optical fiber 36 and outputs it to the light receiver 27. The light receiver 27 converts the received multiplexed pulse train optical signal into a multiplexed pulse train electrical signal and outputs the signal to the receiving circuit 28. The receiving circuit 28 extracts an electric signal component corresponding to two pulse train optical signal components included in the multiplex pulse train electric signal.

In order to determine the optical intensity of the multiplexed pulse train optical signal actually input to the receiving unit 12 in detail, the first
An optical fiber 30, a second optical fiber 32, a light mixing unit 34,
And the transmission efficiency in each of the third optical fiber 36,
Coupling efficiency between the first transmitting node 24 ₁ and the first optical fiber 30, coupling efficiency between the first optical fiber 30 and the optical mixing unit 34,
Coupling efficiency between the second transmission node 24 ₂ and the second optical fiber 32, and the second optical fiber 32 and the coupling efficiency between the light mixer 34, the third coupling efficiency between the optical fiber 36 and the receiving node 26, each efficiency It is necessary to consider variations and the like. In particular,
The length of the transmission path constituted by the optical fiber and the optical mixing section 34, the composition of the material of the optical fibers 30, 32, 36 and the optical mixing section 34, and the optical characteristics of the optical signals emitted from the light emitters 22 ₁ and 22 ₂ The transmission efficiency of the optical transmission unit 14 greatly differs depending on the wavelength. Therefore, it is necessary to finally determine the light intensity of the multiplexed pulse train optical signal input to the receiving unit 12 in consideration of each coupling efficiency and transmission efficiency.

[0040] Here, the waveform of the pulse train optical signal input from the first transmission node 24 ₁ to the optical transmission unit 14 FIG. 2 (A)
To indicate shows the waveform of the pulse train optical signal input from the second transmission node 24 ₂ to the optical transmission unit 14 in FIG. 2 (B). Further, as shown in FIG. 3, the light intensity level of the multiplexed pulse train signal received by the receiving node 26 is an optical signal having a light intensity level obtained by adding these two types of pulse train signal waveforms.

As shown in FIG. 2 (A), the "1" level of the light intensity level of the pulse train optical signal input from the first transmission node 24 ₁ to the optical transmission unit 14 h _1, the "0" level light The light intensity level of the signal is l ₁ (where l ₁ <h ₁ ), and FIG.
The "1" in the level of the optical signal intensity level of the pulse train optical signal input from the second transmission node 24 ₂ to the optical transmission unit 14 as shown in (B) h ₂ (where, h ₁ <h _2), The light intensity level of the “0” level light signal is l ₂ .

The transmission efficiency of the first optical fiber 30 is represented by X
_a , the transmission efficiency of the second optical fiber 32 is X _b , the transmission efficiency of the third optical fiber 36 is X _c , and the transmission efficiency of the optical transmission unit 14 is Y, the two optical signal transmission units 10 ₁ , 10 ₂ And the light intensity level of the optical signal transmitted by each of the
The relationship between the light intensity level of the optical signal input to 2 and the light intensity level can be represented as a logical table shown in Table 1 below.

Here, in order to simplify the explanation,
Coupling efficiency between the first transmission node 24 ₁ and the first optical fiber 30, the coupling efficiency between the first optical fiber 30 and the optical transmission section 14,
Coupling efficiency between the second transmission node 24 ₂ and the second optical fiber 32, and a second coupling efficiency between the optical fiber 32 and the optical transmission section 14 is all 1, omitting calculations assuming no variation Each coupling efficiency I do.

[0044]

[Table 1]

As shown in this logical table, the receiving unit 1
By determining in advance which light intensity level the 2 will receive, a pulse train optical signal to be extracted can be identified from these added signals. In particular,
The pulse train optical signal to be extracted is identified as described below.

FIG. 4 is a diagram for explaining signal identification processing in the receiving circuit 28 of the receiving unit 12. Receiver 12
Each of the light intensity levels P ₀ , P ₁ , P ₂ , and P ₃ received by the receiving circuit 28 are converted into voltage levels V ₀ , V ₁ , V ₂ , and V ₃ by the receiving circuit 28, respectively. Here, it is assumed that the photoelectric conversion efficiency in the light receiver 27 is Z, the signal amplification factor of the amplifier is G, and the offset voltage is V _offset . This amplifier plays the role of amplifying the signal to a predetermined level, and may be built in either the light receiver 27 or the receiving circuit 28. If amplification is not necessary, it can be omitted.

As shown in FIG.
Each time t to pull₁ , T_Two , T _Three , ...
A time-series signal in which the bell changes can be obtained.
2, the time-series signal levels of the received signal
Threshold (here, three thresholds Vth₁, Vth_Two, Vth_Three) And ratio
At some time t_i Signal level St at (St <V
th_Three) Or (St> Vth₁) And (St <Vth
_Two) Or if one of the conditions is met
Shinbe 10₁Classified as a logical "1" optical signal incident from
(St> Vth_Two), The optical signal transmitting unit 10_TwoOr
The signal is classified as a logical "1" optical signal that has been incident. This
Thus, a desired signal is obtained from the multiplex pulse train optical signal shown in FIG.
A Luth train optical signal is extracted.

[0048] However, by X _a and the light intensity level h ₁ at the time values and transmission _{X b, h 2, l 1} , l 2, the value of the logical table of Table 1 is changed individually. That is, the length of the transmission path constituted by the optical fiber and the light mixing section 34, the composition of the material of the optical fibers 30, 32, 36 and the light mixing section 34, and the optical signal emitted from the light emitters 22 ₁ and 22 ₂ The light intensity level received by the receiving unit 12 changes according to the optical wavelength and the light intensity level of the pulse train light signal incident on each of the transmission nodes 24 ₁ and 24 ₂ .

As a result, as shown in FIG.
_0, distance V _1, V _2, V ₃ is not uniform, Vth _1,
At the threshold levels of Vth ₂ and Vth ₃ , it may not be possible to identify correctly.

Therefore, in the optical signal transmission device according to the first embodiment, X _a , X _b , h ₁ , h ₂ , l ₁ , l ₂ are set so that a predetermined margin can be secured for each threshold voltage. I am adjusting. For example, the received light intensity shown in FIG. 3, P ₀ , P ₁ , P ₂ ,
And, the _{P 3, P 1 -P 0 =} P 2 -P 1 = P 3 such that -P ₂ (i.e. _{X b (h 2 -l 2)} = 2 × X a (h 1 -l 1) become so) X _a, X _b, and adjusts the _{h 1, h 2, l 1} , l 2. Specifically, the optical fiber and the optical mixing unit 34 are set so that each light intensity level of the multiplexed pulse train optical signal received by the optical signal receiving unit is equal to or higher than each threshold voltage set for each light intensity level. , The composition of the materials of the optical fibers 30, 32, 36 and the light mixing section 34, the optical wavelengths of the optical signals emitted from the light emitters 22 ₁ , 22 ₂ , and the transmission nodes The light intensity level of the pulse train light signal incident on 24 ₁ and 24 ₂ is adjusted. By making such adjustments, it is possible to accurately extract the superposed pulse train optical signal, thereby achieving stable identification and maintaining transmission quality.

In the first embodiment, the case where the optical transmission section 14 is composed of the first optical fiber 30, the second optical fiber 32, the optical mixing section 34, and the third optical fiber 36 will be described. Although described, the present invention is not limited to this configuration, and for example, a waveguide or a light guide may be used instead of the optical fiber. Further, the light mixing unit 34 may be any unit that mixes a plurality of optical signals, such as an optical fiber coupler (optical multiplexer) and a sheet transmission medium.

Since the sheet-like transmission medium has both the function of propagating the optical signal and the function of superimposing the input optical signal, the sheet-like transmission medium can be applied to the optical transmission unit 14. .

The sheet-shaped optical transmission medium is a flat plate-shaped member having an optical transmission function of propagating the incident light.
An optical data bus such as that described in Japanese Patent Publication No. 0 can be applied.

For example, as shown in FIG. 5, the optical data bus includes an optical transmission layer 40 for transmitting an optical signal, a cladding layer (not shown) having a lower refractive index than the refractive index of the optical transmission layer, A structure in which the light-shielding layers 42 are alternately stacked in multiple layers can be used. The light transmission layer 40 is
For example, a material made of a plastic material such as PMMA (polymethyl methacrylate) having a thickness of about 0.5 mm is preferable.
A fluoropolymer having a thickness of about μm is preferable.
For example, carbon black-containing PMMA having a thickness of about 0.5 mm is suitable.

In the case of this configuration, the sheet-shaped optical transmission medium and 2
Strictly assembling accuracy between the two transmitting units (the first transmitting unit 10 ₁ and the second transmitting unit 10 ₂ ) or optical alignment between the sheet-shaped optical transmission medium and a transmission medium such as an optical fiber. Since there is no need to perform this, assembly efficiency is high and manufacturing costs can be reduced. In addition, since the sheet-shaped optical transmission medium can also be made of an inexpensive material, the cost of raw materials can be reduced.

[0056] In the first embodiment described above, the first transmission unit 10 ₁ and the second transmission unit 10 _2, configured so that the pulse train optical signals of different light intensity levels with each other is outputted fixedly However, the present invention is not limited to this configuration.

For example, the first transmission unit 10 ₁ and the second transmission unit 10 ₂ are configured to be able to change the light intensity level of the optical signal respectively generated, and as shown in FIG. 6, the first transmission unit 10 ₁ and second as the light intensity level of the optical signal generated by the respective transmission unit 10 ₂ are different from each other, the light intensity adjusting the light intensity level of the optical signal transmitted from the two transmitting portions 10 _1, 10 ₂ It is also possible to provide the level adjusting means 16.

Note that the light intensity level of the optical signal is adjusted as shown in FIG.
As shown in (1), a single light intensity level adjusting means 16 may be used to adjust the light intensity levels of all the transmitting units, or a light intensity level adjusting means 16 may be provided for each transmitting unit and each light transmitting level may be adjusted. The light intensity level can be set for each unit. At this time, the light intensity level of the multiplexed pulse train signal received by the reception unit 12 may be fed back to control the light emission intensity of each transmission unit according to the corresponding light intensity level.

In the first embodiment, an optical signal transmission device having two transmission units has been described for the sake of simplicity. However, the present invention relates to an optical signal transmission device having two transmission units. The present invention can be applied not only to the transmission device but also to an optical signal transmission device having three or more transmission units. In this case, the transmission efficiency, the coupling efficiency, the variation of each efficiency, and the like of each member are adjusted between the respective transmission units and the optical transmission units, and between the optical transmission units and the reception units in the same manner as described above.

For example, in an optical signal transmission device having three transmission units as shown in FIG. 7, if the light intensity levels of the optical signals emitted from the respective transmission units are different, the reception is detected by the reception unit. light intensity levels included in the multiplexed pulse train optical signal is composed of P ₀ and seven P _7.

Here, the optical signal transmission having the configuration shown in FIG.
The first transmission unit 10₁Third transmission unit 10 having the same configuration as_Three
Are further provided, and the same components are denoted by the same reference numerals.
The description is omitted here. Note that, in FIG.
Of the third transmission node 24_ThreeIs input to the optical transmission unit 14 from
The light intensity level of the “1” level of the pulse train optical signal is represented by h
_Three(However, h_ThreeIs any number and h_Two<H_Three), "0"
Let the light intensity level of the bell optical signal be l_Three(However, l_ThreeIs any
Number and l_Three<H_Three). Also, the third transmission node 2
4_ThreeThe transmission of the fourth optical fiber 33 connecting the
X transmission efficiency_d, Three optical signal transmission units 10₁, 1
0_Two, 10_ThreeThe optical intensity level of the optical signal transmitted by each of
And the light intensity level of the optical signal input to the receiver 12.
The staff must be represented as a logical table in Table 2 below.
Can be.

[0062]

[Table 2]

As described above, the number of optical signal transmitting units provided in the optical signal transmitting apparatus and the configuration of the optical transmitting unit 14 (ie,
The general formula of the light intensity level calculation formula is determined according to the configuration of the transmission path for transmitting the optical signal). By creating a logic table based on the determined general formula, the pulse train optical signal Even if the number of types increases, it is possible to identify a pulse train optical signal to be extracted from these added signals by previously determining which light intensity level the receiving unit 12 receives based on the logic table. Can be.

The relationship between the number of optical signal transmitters and the number of light intensity levels of the optical signal may be such that light intensity levels equal to the number of optical signal transmitters may be provided or that the number of light intensity levels may be smaller than the number of optical signal transmitters. Transmission may be performed according to the number of intensity levels.

In the first embodiment, each of the transmitting sections 10 ₁ and 10 ₂ is provided with the transmitting nodes 24 ₁ and 24 _2. However, each of the transmitting sections 10 ₁ and 10 ₂ is connected to the transmitting node. 24
_1, 24 ₂ and may be have been formed integrally, or may be detachably attached. Receiving unit 12 and receiving node 2
Similarly, 6 may be integrally formed or may be configured to be detachable.

In the optical transmission section 14, the connection between the first optical fiber 30 and the optical mixing section 34, the second optical fiber 32
The connection between the light mixing unit 34 and the light mixing unit 34 and the connection between the light mixing unit 34 and the third optical fiber 36 may be integrally formed or may be configured to be detachable.

The optical transmission section 14 of this embodiment is composed of an optical fiber and an optical mixing section 34.
Not limited to this configuration, the optical transmission unit 14 may be configured only with a light guide, the optical transmission unit 14 may be configured only with an optical waveguide, only a sheet-shaped optical transmission medium, an optical fiber, a sheet-shaped optical transmission Any of a medium, a light guide path, and a light mixing unit may be configured to combine at least two of them.

Further, in the first embodiment, a configuration has been described in which the transmitting section and the receiving section are separate from each other. For example, as shown in FIG.
The transmission / reception unit 11 including the light emitter 22, the light receiver 27, and the reception circuit 28 and configured to be able to execute both transmission and reception of the pulse train optical signal via the transmission / reception node 23 can be provided.

Further, in the first embodiment, one transmission unit 10 ₁ , 10 ₂ , one reception unit 12, three optical fibers 30, 32, 36 and one optical mixer 34 are provided.
Although the optical signal transmission device including the two optical transmission units 14 has been described, the present invention is not limited to the optical transmission device having such a configuration, and three or more transmission units may be provided or the reception unit may be provided. 12 can be provided. In addition, a configuration may be used in which a plurality of optical fibers are used or a configuration in which the optical fibers are not used. Further, it is also possible to provide a plurality of optical mixers 34.

Further, the light emitting device 22 and the transmitting circuit 20, and the light receiving device 27 and the receiving circuit 28 are not separate ones,
It may be integrated like a multi-chip module. In the case of the configuration shown in FIG. 8, the transmitting unit 10 and the receiving unit 12 may be integrated like a multi-chip module.

For controlling the light intensity level, for example,
The magnitude of the driving voltage of the light emitting device 22 may be controlled by the light intensity level adjusting means 16 shown in FIG. 6 to directly change the light intensity of the optical signal emitted from the light emitting device 22, or an LED or the like. A plurality of light emitting devices may constitute one light emitting device, and the light intensity level may be controlled by changing the light emission ratio of the plurality of light emitting devices. As shown in FIG. 9, an optical signal is transmitted to at least one of an optical signal transmitting side such as between the optical signal transmitting unit 10 and the transmitting node 24 or an optical signal receiving side such as between the receiving node 26 and the receiving unit 12. An attenuator 25 may be provided, and the optical attenuator may be configured to adjust the light intensity level of the optical signal incident on the light receiving unit.

Further, in the above example, the threshold voltages Vth ₁ , Vth ₂ , and Vth ₃ of the optical signal receiving section have been described as fixed, but V ₀ <Vth ₁ <V ₁ <Vth ₂ <V ₂ <Vth ₃ < V ₃ and may be from time to time adjusted to be. For example, V ₀ , V ₁ , V ₂ ,
Respective intermediate level V _3, i.e. _{Vth 1 = (V 1 + V} 0)
/ 2, Vth ₂ = (V ₂ + V ₁ ) / 2, Vth ₃ = (V ₂ + V ₁ ) / 2
Vth ₁ , Vth ₂ and Vth ₃ are controlled so that By doing so, the margin of the threshold voltage can be further secured in the above invention, and the transmission quality can be further improved.
Further, in the above invention, it is effective when the light intensity level of the optical signal transmission unit cannot be completely adjusted from the output limit of the light emitting device and the difference in light intensity level cannot be avoided.

(Second Embodiment) The first embodiment described above
In the optical signal transmission device having the same configuration as
A pulse train optical signal having rising timing is transmitted to the first transmitting unit 10.
₁, The second transmission unit 10_TwoIf sent from each of
However, that of the first optical fiber 30 and the second optical fiber 32
The propagation time changes depending on the difference in length, and the receiving unit 12
Will be shifted in timing. This timing
Is large, the light intensity increases as shown in FIG.
The superposition state of the levels is greatly shifted,
Ring time t ₁ , T_Two , T_Three , ...... to accurately receive the signal
In some cases, it cannot be identified.

In the second embodiment, taking this into consideration, in the optical signal transmission apparatus having the same configuration as that of the above-described first embodiment, the first transmitter 10 transmits the pulse train optical signal having the same rising timing. _1, when transmitted from the second respective transmission unit 10 _2, between leading edge timing of the pulse train optical signal incident on the receiver 12 to the shift amount of the timings start to subsequent sampling timing, a pulse train of light incident after The length of the transmission path constituted by the optical fiber and the optical mixing unit 34 and the transmission timing of each of the first transmitting unit 10 ₁ and the second transmitting unit 10 ₂ so that the optical signal enters the receiving unit 12. At least one is adjusted.

As a result, the two pulse train optical signals are always overlapped at the sampling timing, and the voltage value detected at the sampling timing matches the actual signal overlapping state. Therefore, the original pulse train optical signal can be accurately extracted from the superimposed multiple pulse train optical signals, and stable identification can be realized and transmission quality can be maintained.

Further, in order to simplify this adjustment, the light intensity levels of the optical signals emitted from the optical signal transmitting units 10 ₁ and 10 ₂ are fixed, and the shape and material composition of the optical transmitting unit 14 are fixed. And the same optical wavelength of the pulse train optical signal emitted from each of the light emitters 22 ₁ and 22 ₂ , and the length of the optical transmission unit 14 is made equal. With such a configuration, the optical signal transmission unit 1 that performs intensity multiplex transmission
Since the transmission efficiency of the optical transmission unit 14 into which the optical signals from 0 ₁ and 10 ₂ are incident becomes equal, the amount of light loss can be made uniform.

In the case of this configuration, for example, the threshold level set for each of the plurality of light intensity levels included in the multiplexed pulse train signal when the respective pulse train optical signals are superimposed is set to the difference between the threshold level lower by one step and the threshold level When the difference from the high threshold level is a fixed interval, that is, P ₁ −P ₀ = P ₂
In the case where −P ₁ = P ₃ −P ₂ , the light emitting device 2
The light intensity level of the optical signal emitted from the _{2 1,} (h 2 -
l ₂ ) = 2 × (h ₁ −l ₁ ). Also, the optical transmission unit 14
Signal transmission time in the optical signal transmission unit 1
The transmission timings of the optical signals from 0 ₁ and 10 ₂ may be fixed so as to be simultaneous.

As described above, the light intensity levels of the optical signals emitted from the optical signal transmitting units 10 ₁ and 10 ₂ are fixed, and the shapes and materials of the optical transmitting units 14 are the same.
2 _1, 22 ₂ of the optical wavelength of the pulse train optical signal emitted from each well using the same thing, by equalizing the length of the optical transmission section 14, can be omitted individual adjustment, and stable identification It can realize and maintain transmission quality.

The other configuration is almost the same as that of the first embodiment, and the description is omitted.

In the first embodiment, each light intensity level of the multiplexed pulse train optical signal received by the optical signal receiving unit is set to be equal to or higher than each threshold voltage set for each light intensity level. The length of the transmission path constituted by the optical fiber and the optical mixing section 34, the composition of the material of the optical fibers 30, 32, 36 and the optical mixing section 34, and the optical characteristics of the optical signals emitted from the light emitters 22 ₁ and 22 ₂ Wavelength, and further, each transmitting node 24 ₁ , 2
4 ₂ light intensity levels of the pulse train optical signal incident to adjust, in the second embodiment, the first transmission unit 10 ₁ of the pulse train optical signal having the same rise timing, the second transmission unit 10 ₂
In the case of transmission from each of the above, the timing shift amount is such that the subsequent pulse train optical signal is incident on the receiving unit 12 from the rising timing of the pulse train optical signal which first enters the receiving unit 12 to the sampling timing of the subsequent stage. the optical fiber and the light mixing unit 34 by configured transmission path length, and the first transmission unit 10 _1, although adjusting at least one of the second respective transmission timing of the transmission unit 10 _2, the It is also possible to configure so as to perform both the adjustment of the first embodiment and the adjustment of the second embodiment.

As another means, the transmission efficiency of the optical transmission unit 14 can be prevented from remarkably lowering by designing the length of the optical transmission unit 14 into which the optical signal is incident as short as possible. It is possible to prevent the rate of decrease in light intensity due to propagation absorption and the remarkable difference in propagation time difference between optical signals.

According to this configuration, the length, shape, material composition, and composition of the optical transmission unit 14 into which the optical signal from the optical signal transmission unit performing the intensity multiplex transmission is input, and from the optical signal transmission unit performing the intensity multiplex transmission. Since it is not necessary to strictly design various components in consideration of the optical wavelength of the optical signal and the timing of transmitting the optical signal, there is an advantage that the adjustment accompanying this can be almost omitted.

[0083]

As described above, in the optical signal transmission apparatus of the present invention, the original pulse train optical signal can be accurately extracted from the superposed multiplex pulse train optical signal.
An effect is obtained that the pulse train optical signal can be transferred between a plurality of terminals with high transmission quality.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a schematic configuration of an optical signal transmission device according to a first embodiment of the present invention.

FIG. 2A is a graph showing a waveform of a pulse train optical signal input to an optical transmission unit from a first transmission node shown in FIG. 1, and FIG. 2B is a graph showing a waveform of a pulse train optical signal shown in FIG. 6 is a graph illustrating a waveform of a pulse train optical signal input to an optical transmission unit from two transmitting nodes.

FIG. 3 is a graph showing a light intensity waveform of an optical signal having a light intensity level obtained by adding two types of pulse train signal waveforms shown in FIG. 2;

FIG. 4 is a graph showing a light intensity level waveform obtained by converting the light intensity of the optical signal of the light intensity level shown in FIG. 3 into a voltage.

FIG. 5 is a schematic perspective view showing a configuration example of a sheet-shaped transmission medium as an optical transmission unit.

FIG. 6 is an explanatory diagram illustrating a schematic configuration of an optical signal transmission device according to another embodiment of the present invention.

FIG. 7 is an explanatory diagram illustrating a schematic configuration of an optical signal transmission device according to yet another embodiment of the present invention.

8 includes a transmission circuit, a light-emitting device, a light-receiving device, and a reception circuit instead of the transmission unit and the reception unit in the optical signal transmission device illustrated in FIG. 1, and transmits and receives a pulse train optical signal via a transmission / reception node. 1 is a configuration example of a transmission / reception unit in a case where a transmission / reception unit configured to execute both of them is provided.

9 provides an optical attenuator between the optical signal transmission unit and the transmission node in the optical signal transmission device shown in FIG. 1, and adjusts the optical intensity level of the optical signal incident on the light receiving unit by the optical attenuator. This is an example of the configuration of the case.

FIG. 10A is a waveform diagram showing the light intensity of the pulse train optical signal transmitted from the first optical signal transmitting unit converted into a voltage value, and FIG. FIG. 10C is a waveform diagram showing the light intensity of the pulse train optical signal transmitted from the optical signal transmission unit converted into a voltage value, and FIG.
FIG. 11 is a waveform diagram in which the light intensity of a multiplexed pulse train optical signal in which the pulse train optical signal shown in FIG. 10A and the pulse train optical signal shown in FIG.

FIG. 11A is a graph showing the light intensity levels of a multiplexed pulse train optical signal when the light absorption loss of two pulse train optical signals is significantly different, and FIG. 11B is a graph showing the two pulse train optical signals. 7 is a graph showing a light intensity level when the timing of entering the optical signal receiving unit is shifted.

[Explanation of symbols]

10 ₁ to 10 ₃ transmission unit 11 reception unit 12 receiver unit 13 transmits the node 14 the optical transmission unit 16 the light intensity level adjusting means 20 ₁ to 20 ₁ transmitting circuit 22 ₁ to 22 ₃ emitters 24, 24 _{1-24 3} Submit Node 25 Optical attenuator 26 Receiving node 27 Optical receiver 28 Receiving circuit 30, 32, 33, 36 Optical fiber 34 Optical mixing unit 40 Optical transmission layer 42 Light shielding layer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masao Funada 430 Nakaicho Sakai, Ashigara-gun, Kanagawa Green Tech Nakai Fuji Xerox Co., Ltd. (72) Inventor Ken Uemura 430 Sakai Nakaicho Sakai, Kanagawa Prefecture Green Tech Nakai Fuji Xerox (72) Inventor Hidenori Yamada 430 Nakai-cho, Nakai-machi, Ashigara-kami, Kanagawa Prefecture Inside Green Tech Nakamura Fuji Xerox Co., Ltd. Junji Okada 430 Sakai Nakaicho, Ashigara-gun, Kanagawa Prefecture Green Tech Nakai Fuji Xerox Co., Ltd. (72) Inventor Kazuhiro Sakai 430 Sakai Nakaicho Sakaigami, Kanagawa Prefecture Green Tech Nakai Fuji Xerox Co., Ltd. (72) Akita Shinobu Koseki 430, Nakai-cho, Nakai-machi, Ashigarashimo-gun, Kanagawa Prefecture Inside Green Tech Nakafuji Fuji Xerox Co., Ltd. Fuji Xerox Co., Ltd. (72) Inventor Kenichi Kobayashi Kenichi Kobayashi, Kanagawa Pref., Japan 430 Green Tech Nakai Fuji Xerox Co., Ltd. (72) Inventor Tsuyoshi Yaguchi 2274 Hongo, Ebina-shi, Kanagawa Fuji Fuji Xerox Corporation Ebina Office (72) Inventor Kazuhiro Hama 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Corporation Ebina Office (72) Inventor Riki Matsui 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Corporation Ebina Business (72) Inventor Yasuhiro Arai 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd. Name business premises (72) inventor Hirotaka Mori Ebina, Kanagawa Prefecture Hongo 2274 address Fuji zero box Co., Ltd. Ebina house F-term (reference) 2H037 AA01 BA02 BA11 5K002 AA01 AA03 BA02 BA04 CA09 DA05 FA01 5K022 BB01 BB21 BB22

Claims (6)

[Claims] A plurality of optical signal transmitting means for generating and transmitting pulse train optical signals having different light intensity levels; and a plurality of pulse train optical signals transmitted from each of the plurality of optical signal transmitting means, An optical transmission unit having a light guide path for transmitting a multiplexed pulse train optical signal in which the plurality of pulse train optical signals are mixed; a receiving unit for receiving the multiplexed pulse train optical signal transmitted by the optical transmission unit; and the receiving unit From the received multiple pulse train optical signal, according to the light intensity level of the plurality of pulse train optical signals and the threshold level determined according to the number of the pulse train optical signals,
Optical signal extracting means for extracting the pulse train optical signals individually emitted by the plurality of optical signal transmitting means, wherein the light intensity levels of the plurality of pulse train optical signals reaching the receiving means are individually pulse train light. The coupling efficiency of each of the plurality of optical signal transmitting units and the optical transmitting unit, and the coupling efficiency of the optical transmitting unit and the receiving unit so that the light intensity level is equal to or higher than a threshold level determined for each signal. At least one of a coupling efficiency, a length of the light guide path, a shape of the light guide path, a composition of a material of the light guide path, an optical wavelength of the pulse train optical signal, and a light emission intensity level of the optical signal transmitting unit is adjusted. An optical signal transmission device, characterized in that: 2. The optical system according to claim 1, wherein the threshold level is a first light intensity level and a second light which is one step lower or one step higher than the light intensity level among the light intensity components of the multiplexed pulse train optical signal received by the receiving means. 2. The optical signal transmission device according to claim 1, wherein the optical signal transmission device is set at an intermediate level between the intensity level and the intensity level. 3. The length of the light guide path and the optical signal transmitting means so that the shift amount of the incident timing of the plurality of pulse train optical signals incident on the receiving means falls within a predetermined range. 3. The optical signal transmission device according to claim 1, wherein at least one of output timings of the pulse train optical signal to be transmitted is controlled. 4. A plurality of optical signal transmitting means for generating and transmitting pulse train optical signals having different light intensity levels, and a plurality of pulse train optical signals transmitted from each of the plurality of optical signal transmitting means are input; An optical transmission unit having a light guide path for transmitting a multiplexed pulse train optical signal in which the plurality of pulse train optical signals are mixed; a receiving unit for receiving the multiplexed pulse train optical signal transmitted by the optical transmission unit; The pulse train optical signals individually generated by the plurality of optical signal transmission means according to the light intensity of the plurality of pulse train optical signals and the threshold level determined according to the number of the pulse train optical signals from the multiplexed pulse train optical signal obtained Optical signal extracting means for individually extracting a plurality of pulse train optical signals incident on the receiving means, wherein a shift amount of the incident timing of the plurality of pulse train optical signals is a predetermined range. To fit within, the light path length, and optical signal transmission apparatus, wherein at least one of which is the control of the output timing of the pulse train optical signal the optical signal transmitting unit sends out. 5. The method according to claim 1, wherein the predetermined range is determined based on a rising timing of a previously input pulse train optical signal.
The optical signal transmission device according to claim 3, wherein the optical signal transmission device is within a range between a timing determined within a unit pulse width in advance. 6. The optical transmission means, wherein: a diffusion optical system for diffusing light from the optical signal transmission means; and a light diffused by the diffusion optical system is incident and propagates through a light guide path formed therein. The optical signal transmission device according to claim 1, further comprising: a sheet-shaped optical transmission medium.