JP4444159B2 - Optical communication device - Google Patents

Description

The present invention relates to an optical communication device using an optical sensor that can easily eliminate the influence of disturbance light using modulated light .

Conventionally, an optical communication device that performs information communication using modulated light (for example, see Patent Document 1) and an object detection device that detects an object by an image sensor using modulated light (for example, see Patent Document 2) have been proposed. Has been.
In the conventional optical sensor used in this type of optical communication device, when the communication distance is long, the light of the communication partner light source is set by narrowing the directivity so that only the communication partner light source exists in the detection region. Only to receive light. Thereby, it is avoided that the light of the light source of the communication partner cannot be detected due to the influence of disturbance light.
Further, in the conventional image sensor of this type of object detection apparatus, the conversion timing of the photoelectric conversion element of the image sensor is synchronized with the modulated light, and the current during the photoelectric conversion is integrated to receive the modulated light. Try to incorporate images based on it.
Japanese Patent No. 3499694 Japanese Patent Laid-Open No. 10-281868

However, if the directivity is set narrow like the optical sensor of the conventional optical communication device, it is necessary to align the optical axis with high accuracy, and it is difficult to align the optical axis when applied to a moving body such as a railway vehicle or an automobile. However, there is a problem that it is difficult to apply to an optical communication system in which at least one station is a mobile station.
Further, in the method of integrating the received light signal as in the image sensor of the conventional object detection device described above, in a situation where another light source exists, the offset (DC component) due to the light (disturbance light) of the other light source is calculated. It cannot be removed. In order to eliminate the influence of this disturbance light, a separate process for removing the offset from the output of the image sensor is necessary, and the image processing for object detection becomes complicated.
The present invention has been made paying attention to the above-mentioned problems , and it is not necessary to adjust the optical axis, and the transmission information of the signal lamp is transmitted on the vehicle side using an optical sensor that can easily eliminate the influence of disturbance light. An object of the present invention is to provide an optical communication device that can be obtained .

For this reason, in the optical communication device according to claim 1 of the present invention, a light emitting unit that emits modulated light that is spread-modulated with a spreading code, and a plurality of photoelectric conversion elements are arranged in a matrix and are used as modulated light of the light emitting unit. An image pickup unit that converts an optical image based on an electric signal, and a light receiving output of each photoelectric conversion element of the image pickup unit by performing a reverse diffusion process for each photoelectric conversion element using the same diffusion code as the diffusion code and performing the modulation A despreading processing unit that extracts only a light reception output corresponding to light , and a light emitting unit of a communication partner based on a correlation output for each photoelectric conversion element of the despreading processing unit of the photosensor. A position specifying unit for specifying a position; and an information extracting unit for extracting transmission information included in the modulated light of the light emitting unit specified by the position specifying unit, wherein the light emitting unit is a signal lamp in front of the vehicle, Imaging unit, despreading processing unit, position specifying unit and information extraction Mounted on the vehicle side, the modulated light emitted from the signal lamp is directly received by the imaging unit on the vehicle side, and the transmission information included in the modulated light emitted from the signal light of the communication partner is acquired on the vehicle side. It is characterized by having a configuration to do.

In such a configuration, modulated light that is spread-modulated with a diffusion code is emitted from a signal lamp that is a light emitting unit , and modulated light from the signal lamp is received by an imaging unit in which photoelectric conversion elements are arranged in a matrix on the vehicle side, and the optical image thereof Is converted into an electrical signal. The inverse conversion processing unit calculates the correlation between the photoelectric conversion elements for each photoelectric conversion element by performing a despreading process using the same spreading code as the spreading code of the signal lamp , with respect to the light reception output of each photoelectric conversion element based on the reception of the modulated light. As a result, only the received light output based on the modulated light from which the offset amount of the disturbance light (DC component) is removed can be obtained from the inverse conversion processing unit. Then, based on the correlation output for each photoelectric conversion element of the despreading processing unit of the optical sensor, the position specifying unit specifies the position of the signal lamp from the imaging position of the signal lamp in the imaging unit of the optical sensor. The information extraction unit extracts transmission information included in the modulated light of the signal lamp specified by the position specifying unit.

According to a second aspect of the present invention, an exposure adjustment unit that adjusts exposure for each photoelectric conversion element of the imaging unit may be provided.
In such a configuration, the exposure of each photoelectric conversion element is adjusted according to the light reception level, so that even if there is a part with an extremely different light reception level in the imaging unit, appropriate exposure processing can be performed according to each light reception level. become.

In addition, after specifying the position of the light emitting unit of the communication partner by the position specifying unit as in claim 3, the imaging unit is limited to the periphery of the light receiving region where the modulated light of the specified light emitting unit is received. The light receiving output of each photoelectric conversion element may be reversely converted by the reverse conversion processing unit.

According to a fourth aspect of the present invention, the transmission information may be signal lamp display information.

Further, as in claim 5, the transmission information included in the modulated light emitted by the signal lamp may include ID number information that is identification information of each signal lamp.

According to the optical communication device of the present invention, the modulated light from the signal lamp as the light emitting unit is received as an image by the two-dimensional imaging unit, so there is no need to adjust the optical axis between the light emitting side and the light receiving side, and the movement there is no need to provide an optical axis adjusting mechanism as the body light communication apparatus can simplify the configuration of the mobile optical communication system. In addition, since the light emitted from the signal lamp is converted into modulated light that has been subjected to diffusion processing using a diffusion code, and the reverse diffusion processing is performed on the light receiving side of the modulated light, the influence of disturbance light on the light reception output can be easily removed. Therefore, it is not necessary to separately perform processing for removing the influence of disturbance light on the output of the optical sensor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram showing an embodiment of an optical sensor applied to the optical communication apparatus of the present invention.
In FIG. 1, an optical sensor 1 according to the present embodiment includes a light emitting unit 2, an image detection unit 3 as an imaging unit, a correlation processing unit 4 as a despreading processing unit, and an exposure adjustment unit 5. The

  The light emitting unit 2 emits modulated light that is spread-modulated by, for example, a PN code that is a pseudo-random code as a spread code, and includes a modulation unit 2A and a light source 2B. The modulation unit 2A includes a PN code generator that generates, for example, a PN code as a spread code, and spread-modulates light emitted from the light source 2B. The light source 2B is a light source suitable for modulation such as an LED or a laser light source, and projects the modulated light a modulated by the PN code generated from the modulation unit 2A to the outside.

  The image detection unit 3 has a matrix of N photoelectric conversion elements that receive the modulated light a from the light emitting unit 2 or the reflected light b from the object of the modulated light a and convert it into an electrical signal (N = n × m). The optical image based on the modulated light is converted into an electric image signal. For example, a photodiode or CMOS may be used as the photoelectric conversion element.

The correlation processing unit 4 despreads each light receiving output of the N photoelectric conversion elements of the image detection unit 3 for each photoelectric conversion element with the same spreading code as the modulated light a, and only the light receiving output based on the modulated light. The same PN code is generated in synchronization with the generation timing of the PN code of the modulation unit 2A, and the light reception outputs of the N photoelectric conversion elements of the image detection unit 3 and the generated PN code The correlation value is calculated to generate a correlation value output for each photoelectric conversion element.
The exposure adjustment unit 5 adjusts the exposure of the image detection unit 3, and adjusts the exposure for each photoelectric conversion element.

Next, the operation of the optical sensor 1 will be described.
A PN code is generated from the modulation unit 2A, the light from the light source 2B is diffusely modulated, and the modulated light a is projected from the light emitting unit 2. When the image detection unit 3 receives the modulated light a or the reflected light b thereof, the exposure adjustment unit 5 controls the exposure time for each photoelectric conversion element according to the light reception level of each photoelectric conversion element. An electrical signal corresponding to the received light level is output to the correlation processing unit 4 . The correlation processing unit 4 generates the same PN code in synchronization with the PN code generation timing of the modulation unit 2A, despreads the electrical signal output from the photoelectric conversion element for each photoelectric conversion element, and calculates the correlation value. Calculate. By this despreading process, the offset (DC component) due to disturbance light is removed. Therefore, an image signal can be directly output from the optical sensor only by the received modulated light without providing a separate processing unit for removing the offset (DC component) due to disturbance light.

Here, it will be described that the influence of disturbance light is removed by the diffusion processing of the correlation processing unit 4.
FIG. 2 shows an example of a modulated light waveform p (t) that is spread-modulated with a PN code, and a received light output waveform r (t) of the photoelectric conversion element of the image detection unit 3 based on the received light of this modulated light. In the modulated light waveform p (t), a high light emission level corresponds to p (t) = 1, and a low light emission level corresponds to p (t) =-1. Therefore, when s0 is an average value of the light emission levels of the modulated light, the light emission level s0 + Δs corresponds to p (t) = 1, and the light emission level s0−Δs corresponds to p (t) = − 1. The received light output waveform r (t) has a received light level of (r0 + Δr (t)) δ when the emitted light level is s0 + Δs, and a received light level when the emitted light level is s0−Δs is (r0−Δr ′ (t)) δ. And Here, δ is the reflectance of the object.

In the despreading process of the correlation processing unit 4, the correlation value is calculated by multiplying the received light output waveform output from the image detection unit 3 by the same PN code as the modulated light.
Now, assuming that the received light output waveform output from the image detector 3 is a waveform r (t) as shown in FIG. 2 in which no disturbance light exists, this waveform r (t) is multiplied by p (t) to obtain a correlation value R. Is calculated as the following equation (1). Here, ∫p (t) = 0.

  On the other hand, when disturbance light is present in the light reception output waveform output from the image detection unit 3, assuming that the disturbance light is n (t), the light reception output waveform output from the image detection unit 3 is (r (t) + n ( t)). Accordingly, the correlation value R at this time is as shown in the equation (2) of Equation 2.

  Since p (t) = 0, the correlation value in the equation (2) is equal to the correlation value in the absence of disturbance light in the equation (1). That is, by performing diffusion processing in the correlation processing unit 4, the offset amount (DC component) of the disturbance light is removed, and a light reception output of only the modulated light from which the influence of the disturbance light is removed is obtained from the optical sensor 1.

  According to the optical sensor 1 of the present embodiment, the light projected from the light emitting unit 2 is converted to the modulated light a obtained by diffusing the PN code, and the received light output from the image detecting unit 3 by the modulated light a or the reflected light b thereof. Therefore, the light receiving output from which the influence of disturbance light (light other than the modulated light a or its reflected light b) is removed can be directly obtained from the optical sensor 1, and the output of the optical sensor can be obtained. Therefore, it is not necessary to separately perform processing for removing the influence of ambient light.

Further, since the modulated light a from the light emitting unit 2 is received by the two-dimensional image detection unit 3, it is not necessary to align the optical axis with high accuracy unlike the optical sensor used in the conventional optical communication device, It can be applied to an optical communication system between a fixed station and a mobile body.
Further, since the exposure adjustment unit 5 controls the exposure time for each photoelectric conversion element of the image detection unit 3, for example, a part of the image detection unit 3 is irradiated with extremely bright disturbance light, and the image detection unit 3. Even if an extreme difference in the light receiving level occurs on the light receiving surface, there is no problem that a dark part cannot be imaged, and an image based on the modulated light from the light emitting unit 2 can be captured reliably and satisfactorily.

Next, an object detection apparatus will be described as a reference example using the above-described optical sensor .
FIG. 3 shows a configuration diagram of the object detection apparatus . Note that the same elements as those in FIG.
In FIG. 3, the object detection apparatus of the present reference example includes the optical sensor 1 of FIG. 1 and an object presence / absence determination unit 10.

The optical sensor 1 detects, for example, an object 11 other than an existing object in the room as an object detection target area. For example, the light source 2B of the light emitting unit 2 is disposed on the ceiling or the like in the room, and the image detection unit 3 is installed in the room. The predetermined monitoring area is placed indoors so that it can be imaged.
The object presence / absence determination unit 10 detects the reflectance from an indoor object that is an object detection target region for each photoelectric conversion element based on the correlation output for each photoelectric conversion element of the correlation processing unit 4 of the optical sensor 1. The actual reflectance detected for each photoelectric conversion element is compared with the reflectance from the existing object in the room stored in advance, and when the reflectance is different, it is determined that there is an object 11 other than the existing object in the room. is there.

Next, the object detection operation of the object detection apparatus of this reference example will be described.
The light source 2B of the light emitting unit 2 of the optical sensor 1 irradiates the room with modulated light a that has been diffusion-modulated with a PN code as described above. Assuming that an object 11 other than the existing object exists on the floor 12 that is an existing object in the object detection target area, the modulated light a is reflected by the object 11 and the floor 12, and the reflected light b is detected by the optical sensor. 1 is received by the image detection unit 3, and the received light output is output to the object presence / absence determination unit 10 as a result of the inverse diffusion processing performed by the correlation processing unit 4 for each photoelectric conversion element as described above. Here, the correlation value output input to the object presence / absence determination unit 10 corresponds only to the modulated light a from which the influence of disturbance light is eliminated.

  The object presence / absence determination unit 10 can know the actual reflectivity for each photoelectric conversion element from the above-described equation (1) based on the input correlation value output for each photoelectric conversion element, and is stored in advance. Compare the reflectance of existing objects. In the case of FIG. 3, if the correlation value output based on the reflected light b of the floor 12 is R0 and the correlation value output based on the reflected light b of the object 11 is R1, the reflectance of the floor 12 and the reflectance of the object 11 are different. From the equation (1), the correlation value output R0 and the correlation value output R1 are different, and the presence of the object 11 on the floor 12, which is an existing object in the room, can be detected.

According to the object detection device of this reference example configured as described above, since the image sensor output is an output from which the influence of disturbance light has already been removed, there is no need to separately provide a processing unit for eliminating disturbance light. Compared with an object detection apparatus using a conventional image sensor, an object can be detected by an image with a simple configuration.

Next, an optical communication apparatus of the present invention using the above-described optical sensor will be described.
FIG. 4 is a configuration diagram showing an embodiment of an optical communication apparatus according to the present invention. Note that the same elements as those in FIG.
4, the optical communication apparatus of the present embodiment includes the optical sensor 1 of FIG. 1, a position specifying unit 21, and an information extracting unit 22.

The optical sensor 1 is configured such that the modulation unit 2A and the correlation processing unit 4 of the light emission units 2-1 and 2-2 operate in synchronization with each other by acquiring a reference time, for example, and the image detection unit 3 emits light. Each modulated light a from the units 2-1 and 2-2 is directly received and the optical image is converted into an electrical signal.
The position specifying unit 21 detects the light receiving position of the modulated light a on the two-dimensional image detection unit 3 based on the correlation value output for each photoelectric conversion element of the correlation processing unit 4 of the optical sensor 1. The position of the light emitting unit 2 of the communication partner to be identified is specified.
The information extracting unit 22 extracts transmission information included in the modulated light a of the light emitting unit 2 specified by the position specifying unit 21.

Next, the operation of the optical communication apparatus according to the present embodiment will be described using an example in which information on a front signal lamp is read on the train side.
In this case, the light emitting units 2-1 and 2-2 are signal lights in front of the vehicle, and the image detecting unit 3, the correlation processing unit 4, the exposure adjusting unit 5, the position specifying unit 21, and the information extracting unit 22 are mounted on the vehicle side. .
Each of the light emitting units 2-1 and 2-2 is previously given ID numbers ID 1 and ID 2 as mutual identification information, and transmits information including this ID number as modulated light a. When the image detection unit 3 directly receives the modulated light a, the correlation processing unit 4 despreads the received light output for each photoelectric conversion element as described above to calculate each correlation value. In this case, for example, if optical images of the light emitting units 2-1 and 2-2 are obtained by receiving the modulated light a as shown in FIG. Correlation value output is obtained. The position specifying unit 21 takes in each correlation value output of the correlation processing unit 4, detects a light receiving position in the image detection unit 3 based on the incorporated correlation value output, and among the received light emitting units 2-1 and 2-2. The position of the light emitting unit of the communication partner for whom information is to be obtained is specified. The position information of the light emitting unit specified by the position specifying unit 21 is sent to the information extracting unit 22, and the information extracting unit 22 acquires information (for example, display information of a signal lamp) based on the correlation value output. Thereafter, the correlation process can be made efficient by performing the correlation process on the output of the image detection unit 3 only in the vicinity of the light receiving area where the modulated light a of the light emitting unit of the specified communication partner is received.

  According to the optical communication apparatus of this embodiment having such a configuration, the influence of disturbance light can be easily eliminated. Further, since the modulated light a from the light emitting unit is received as an optical image by the two-dimensional image detection unit 3, it is not necessary to match the optical axes on the light emitting side and the light receiving side as in the prior art, and the optical axis is adjusted with high accuracy. Is unnecessary. Accordingly, when applied to a mobile communication device, a highly accurate optical axis adjustment mechanism is not required, the configuration of the mobile optical communication device can be simplified, and application to the optical communication device is facilitated.

The block diagram which shows one Embodiment of the optical sensor applied to the optical communication apparatus of this invention Waveform diagram showing an example of modulated light diffused and modulated with a PN code and its received light output Configuration diagram showing a reference example of an object detection device to which an optical sensor is applied The block diagram which shows one Embodiment of the optical communication apparatus which concerns on this invention Explanatory drawing of the light receiving state of the light emitting unit in the image detecting unit

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical sensor 2 Light emission part 2A Modulation part 2B Light source 3 Image detection part 4 Correlation processing part 5 Exposure adjustment part

Claims (5)

A light emitting unit that emits modulated light that is spread-modulated with a spreading code, an imaging unit that includes a plurality of photoelectric conversion elements arranged in a matrix and converts an optical image based on the modulated light of the light emitting unit into an electrical signal, and A despreading processing unit that despreads the light reception output of each photoelectric conversion element for each photoelectric conversion element using the same diffusion code as the diffusion code, and extracts only the light reception output corresponding to the modulated light; An optical sensor with
A position specifying unit for specifying the position of the light emitting unit of the communication partner based on the correlation output for each photoelectric conversion element of the despreading processing unit of the photosensor;
An information extracting unit that extracts transmission information included in the modulated light of the light emitting unit specified by the position specifying unit ;
The light emitting unit is a signal lamp in front of the vehicle, the imaging unit, the despreading processing unit, the position specifying unit, and the information extracting unit are mounted on the vehicle side, and the modulated light emitted from the signal lamp is transmitted by the imaging unit on the vehicle side. An optical communication device characterized in that the transmission information contained in the modulated light that is directly received and emitted from the signal light of the communication partner is acquired on the vehicle side . The optical communication apparatus according to claim 1, further comprising an exposure adjustment unit configured to adjust exposure for each photoelectric conversion element of the imaging unit. After the position of the light emitting unit of the communication partner is specified by the position specifying unit, the light receiving output of each photoelectric conversion element of the imaging unit is limited to the periphery of the light receiving region where the modulated light of the specified light emitting unit is received. The optical communication apparatus according to claim 1, wherein an inverse conversion process is performed by the inverse conversion processing unit . The optical communication apparatus according to claim 1, wherein the transmission information is signal lamp display information. The optical communication apparatus according to claim 1, wherein transmission number information included in the modulated light emitted from the signal lamp includes ID number information that is identification information of each signal lamp.

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