JP2006279747A - Optical transmitter, optical receiver and optical communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the quantity of information to be sent out by N times by increasing the number of light-emitting elements by N times and to rightly separately identify N information lights at a receiving side. <P>SOLUTION: A despreading section (9(2)) includes: an average value extraction circuit (12) which extracts a DC component and a low-frequency components of a signal from a light-receiving section to generate a reference signal comprised of the DC component and the low-frequency component; a polarity switching circuit (13) which inputs the signal from the light-receiving section, a spreading code from a spreading code generating circuit and the reference signal, outputs the spreading code as it is if the spreading code is greater than the reference signal and inverts out the spreading code if the spreading code is smaller than the reference signal; an integration circuit (14) which integrates the signal from the polarity switching circuit and outputs a sample/hold value of the integrated value; and a binarizing circuit (15) for binarizing the output of the integration circuit. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is an optical transmission that can be used for various purposes such as product descriptions at stores, descriptions of exhibits in museums and exhibitions, landmark display of buildings, advertisement display, display of congestion status of amusement facilities such as amusement parks, etc. The present invention relates to an optical receiver, an optical receiver, and an optical communication system.

  Conventionally, the presentation of information on products and exhibits, or the display of landmarks for buildings, advertisements, and the status of amusement parks such as amusement parks have been made exclusively of paper, banners, billboards, plates, etc. For the sake of convenience, it was called “Information Presentation”).

  However, such text-based information presentation is as follows: (1) When there are a large number of information presentation objects, the number of information presentation objects such as signboards increases, and the important objects become inconspicuous, and information presentation objects and information presentation objects It is difficult to understand the correspondence relationship between the product A and the wrong information. For example, the product A information may be misunderstood as the product B information. (2) Since the text information written on the information presentation can be read by anyone with normal vision, limited information (for example, merchandise) In order to present the purchase price and maximum discount rate, etc., we will take conservation measures such as encoding and writing. However, since complicated encoding is not easy to use, it must be simple and information There is a risk that the maintenance effect of the image will be reduced and read easily.

  Therefore, the applicant of the present invention can first make clear the correspondence between the information presentation target product and the presentation information by using information transmission by optical space transmission, and eliminate the misunderstanding of information grasping. System, information transmission method, imaging apparatus and information transmission method "(see Patent Document 1). Hereinafter, the technique according to this proposal is referred to as a conventional technique.

  The principle of the prior art is roughly as follows. For convenience of explanation, transmission information TX sent from the optical transmitter to the optical receiver is assumed to be an 8-bit bit string “01011000”.

  The optical transmitter first performs spreading coding on each bit of the transmission information TX using two predetermined M-bit spreading codes (referred to as C0 and C1). The spreading codes C0 and C1 refer to codes having a repetitive pattern different from a blinking pattern of disturbance light such as natural light. For example, M = 5, C0 = 00101, C1 = 111010, and the like.

  If the spreading code C0 is assigned to the logic 0 of the transmission information TX and the spreading code C1 is assigned to the logic 1 of the transmission information TX, the spread transmission information TX is C0, C1, C0, C1, C1, C0. , C0, C0. That is, transmission information TX, which is an 8-bit bit string (01011000), is spread into M × 8-bit signals (00101, 11010, 00101, 11010, 11010, 00101, 00101, 00101). Note that the commas in parentheses are convenient delimiters for indicating each bit of the transmission information TX.

  The optical transmitter blinks a single light emitting element such as an LED in accordance with the logic (0/1) of each bit of the transmission information TX after spreading, and emits information light having the logical information to the space. This information light is dark (luminance zero or luminance below a predetermined value) when the logic of each bit of the M × 8-bit signal (00101, 11010,...) Is “0”, and the logic is “1”. Is a single blinking light (information light) that becomes bright (brightness that is visually recognized as being brighter than dark or a luminance that is equal to or higher than a predetermined value).

  On the other hand, the optical receiver receives the blinking light of the optical transmitter with a light receiving element, converts the received light signal into a binary signal, and despreads it. The spreading code used for despreading is the same as the spreading codes C0 and C1 of the optical transmitter. In this despreading, the bit sequence of the binary signal is divided into M bits, a match / mismatch between the two spread codes C0 and C1 is determined, and a process of converting to a logic corresponding to the matched spread code is performed. . Specifically, when the bit string of a certain section is “00101”, this bit string matches one spreading code C0, so it is converted to the logic (= 0) of the spreading code C0, and another certain section When this bit string is “11010”, since this bit string matches the other spreading code C1, the process of converting to the logic (= 1) of the spreading code C1 is repeatedly executed for all sections.

  As a result, the blinking pattern of M × 8 bits (00101, 11010, 00101, 11010, 11010, 00101, 00101 and 00101) is finally restored to the 8-bit reception information RX (01011000). Transmission information TX can be reproduced on the receiving side.

JP 2003-179556 A

  Thus, in the prior art, information can be transmitted using blinking of light such as an LED, so that, for example, visible light communication that has recently attracted attention (what is visible light communication: http: / /www.vlcc.net/about.html) and can be used to send arbitrary information to the surroundings using existing light sources such as indoor lighting, street lighting, or signage lighting. However, there is still room for improvement in terms of the amount of information that can be transmitted.

  That is, in the prior art, since information is transmitted by a single blinking light, for example, as shown in the above example, a blinking time in which the number of bits of the transmission information TX is multiplied by the number of bits M of the spread code is required. Because.

  Accordingly, one of the objects of the present invention is to increase the number of light-emitting elements by N and increase the amount of information transmitted N times, and the second object of the present invention is to provide N blinking lights (information light). The purpose is to enable correct separation and identification on the receiving side.

According to the first aspect of the present invention, there is provided a multi-level circuit that multi-values transmission information by dividing it into N bits, a spreading code generation unit that generates N spreading codes, and the multi-level transmission information. Corresponding to the logic of each bit, N diffusion units that output or reversely output the spreading code and N light emitting units driven by signals from each diffusion unit are provided. An optical transmitter is characterized.
According to the second aspect of the present invention, each of the N light receiving units that receive N information lights and convert them into electrical signals, the spread code generating unit that generates N spread codes, and the N light receiving units The N despreading units that output a logic 0 or logic 1 signal based on the phase relationship between the electrical signal output from N and the N spreading codes and the outputs of the N despreading units are received in combination. An optical receiver comprising an information restoration circuit for restoring information.
According to a third aspect of the present invention, the N despreading units extract the DC component and the low frequency component of the signal from the light receiving unit, and generate an average value that generates a reference signal composed of the DC component and the low frequency component. A circuit, a signal from the light receiving unit, a spreading code from the spreading code generation circuit, and the reference signal are input, and when the spreading code is larger than the reference signal, the spreading code is output as it is, and the spreading code is output from the reference signal. A polarity switching circuit that inverts the spreading code when the signal is small, an integration circuit that integrates the signal from the polarity switching circuit and outputs a sample hold value of the integration value, and a binary value that binarizes the output of the integration circuit The optical receiver according to claim 2, further comprising: an optical circuit.
According to a fourth aspect of the present invention, the N light receiving units are N pixels arranged on an imaging surface of a two-dimensional imaging device, and are included in a photographed image photographed by the two-dimensional imaging device. Matching means for detecting a pixel of a reference spreading code from the signal, determining a sampling point of the reference spreading code according to the detection result, and sequentially determining sampling points of other spreading codes starting from the sampling point of the reference spreading code The optical receiver according to claim 2, further comprising:
According to a fifth aspect of the present invention, there is provided an optical communication system including the optical transmitter according to the first aspect and the optical receiver according to any one of the second to fourth aspects.
The invention according to claim 6 is the optical transmitter according to claim 1, wherein the spreading code generator generates N spreading codes while shifting a reference spreading code by a predetermined amount. is there.
According to a seventh aspect of the present invention, in the optical receiver according to the second aspect, the spreading code generator generates N spreading codes while shifting a reference spreading code by a predetermined amount. is there.

The optical transmitter of the present invention includes N light emitting units, and simultaneously emits diffusion-modulated information light from each of the light emitting units into space. Here, if the transmission information amount of one information light is the same as the conventional one, the information amount of the present invention is N times by simple calculation, so that one of the objects can be solved.
The optical receiver of the present invention receives N pieces of information light emitted from the optical transmitter by N pieces of light receiving units, despreads each received light signal, and receives reception information having the same contents as the transmission information. Restore.
Here, when the positional relationship with the N light emitting units of the optical transmitter is ideal, each of the N light receiving units of the optical receiver separates and receives each of the N information lights. However, depending on the positional relationship, a single light receiving unit may receive a plurality of information lights or may receive disturbance light.
In such a case, as in the invention described in claim 3, by forming N despreading units with an average value extraction circuit, a polarity switching circuit, an integration circuit, and a binarization circuit, unnecessary information light and external lines The influence of light can be eliminated, and there is no need to pay attention to the positional relationship between the optical transmitter and the optical receiver.
In addition, such an inconvenience is that, as in the invention of claim 4, N light receiving portions are N pixels arranged on the imaging surface of the two-dimensional imaging device, and the two-dimensional imaging device is used to capture the image. Detects the pixel of the reference spreading code from the captured image, determines the sampling point of the reference spreading code according to the detection result, and sequentially determines the sampling points of other spreading codes starting from the sampling point of the reference spreading code This can also be solved.
Alternatively, when generating N spreading codes, if N spreading codes are generated while shifting a reference spreading code by a predetermined amount, the number of spreading codes to be held is one, The storage capacity of the memory or the like can be reduced, and the cost can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the specific details or examples in the following description and the illustrations of numerical values, character strings, and other symbols are only for reference in order to clarify the idea of the present invention, and the present invention may be used in whole or in part. Obviously, the idea of the invention is not limited. In addition, a well-known technique, a well-known procedure, a well-known architecture, a well-known circuit configuration, and the like (hereinafter, “well-known matter”) are not described in detail, but this is also to simplify the description. Not all or part of the matter is intentionally excluded. Such well-known matters are known to those skilled in the art at the time of filing of the present invention, and are naturally included in the following description.

First, the first embodiment will be described.
FIG. 1 is a configuration diagram of the optical transmitter 1. In this figure, the optical transmitter 1 includes a multilevel circuit 2, a spread code generation circuit 3, a spreader 4 (i), and a light emitter 5 (i). Note that i is 1 to N, and N is an integer exceeding 2. The same shall apply hereinafter. The multilevel circuit 2 converts the transmission information TX given as a serial bit string into N bits, for example, 5 bits each, converts the information into a parallel signal string, and outputs the parallel signal string. Now, let us say that the bit sequence of the transmission information TX is “1010110011...”. If a delimiter (,) of 5 bits is added to this, “10101, 10011,...” Is obtained. In the multilevel circuit 2, the bit string for each segment is converted in parallel. That is, “10101” is output at a time, and then “10011” is output at a time,... Are repeated every predetermined period (the above-described 5-bit delimiter period).

  FIG. 2 is a signal time sequence diagram of the optical transmitter 1. As shown in this figure, the bit sequence of the transmission information TX is “1010110011...”, And the bit sequence parallel-converted by the multi-level circuit 2 is indicated by TX (i) in FIG. Has been. For example, if the delimiter periods of the transmission information TX are T1, T2,..., In the period T1, logic 1, logic 0,. From the top to the bottom, logic 1, logic 0,..., Logic 1 are arranged, and in period T3, logic 1, logic 1,..., Logic 0 are arranged from top to bottom in the drawing, and in period T4 , Logical 0, logical 1... Logical 0 are arranged from the top to the bottom of the drawing. These sequences are on the same time, and therefore, TX (i) is obtained by rearranging the bit strings of the transmission information TX in parallel.

  In FIG. 1 again, the spread code generation circuit 3 generates N spread codes C (i). The spreading code C (i) is, for example, a 7-bit code, and has a repetitive pattern different from a blinking pattern of disturbance light such as natural light as described in the prior art at the beginning. In addition, although the spreading code of the prior art was two, C0 and C1, the difference is that the spreading code C (i) of the present embodiment is N more than two.

  As described above, the N spread codes C (i) may be codes having a repetitive pattern different from the blinking pattern of disturbance light such as natural light as described above. However, N information lights P (i) described later are used. ) On the receiving side, it is desirable that each of the N spread codes C (i) be a different code.

  To that end, N spreading codes C (i) may be generated individually, but in this embodiment, as shown in FIG. 2, a reference spreading code is generated by a predetermined amount (for example, N spreading codes C (i) are generated while shifting by 1 bit). In this way, since only one spreading code needs to be held, the storage capacity of the memory or the like can be reduced, and the cost can be reduced.

  In this way, when N spreading codes C (i) are generated while shifting one reference spreading code by a predetermined amount (for example, by 1 bit), the number of bits of the spreading code is in principle May be at least N bits. N is the number of diffusing parts and light emitting parts (that is, the number of information lights). In the case of the present embodiment, since the number of bits of the spreading code is 7, it is possible to provide up to N = 7, that is, up to 7 spreading parts and light emitting parts. This number (N = 7) is merely for convenience of explanation. The number of N (and therefore the number of bits of the spread code) may be determined according to the amount of information to be transmitted, and may be several tens to several hundreds or more, for example.

  The N spreading units 4 (i) output the corresponding spreading code (i) as it is or invert it according to the logic of each bit of the parallel-converted signal TX (i). For example, paying attention to the spreading unit 4 (1), since the signal TX (1) and the spreading code (1) are input to the spreading unit 4 (1), the logic of the signal TX (1) is “1”. When "is", the spread code (1) is output as it is, and when the logic of the signal TX (1) is "0", the spread code (1) is inverted and output.

  The N light emitting units 5 (i) are composed of a highly responsive light emitting element (for example, LED) and its drive circuit. One light emitting element may be provided for each light emitting section 5 (i), but a plurality of light emitting elements may be combined and provided in each light emitting section 5 (i) in order to emit more powerful light. Good. A signal from the corresponding diffusion unit 4 (i) is added to each light emitting unit 5 (i), and the light emitting unit 5 (i) receives the logic (0/0) of the signal as shown in FIG. The information light P (i) blinking in response to 1) is emitted into space.

  In summary, the optical transmitter 1 according to the present embodiment generates a multilevel circuit 2 that performs parallel conversion by dividing the transmission information TX of the serial example into N bits and generates N spreading codes C (i). And N spreading units that output the spreading code C (i) through or invert corresponding to the logic of each bit of the transmission information TX (i) converted in parallel 4 (i) and N light emitting units 5 (i) driven by signals from each diffusion unit 4 (i), and simultaneously flashing the N light emitting units 5 (i), N pieces of information light P (i) are emitted into space.

  Here, the amount of information transmitted in the optical transmitter 1 of the present embodiment corresponds to the number N of information lights P (i), and is N times that of the prior art at the beginning by simple calculation. Referring to FIG. 2, in the present embodiment, N information beams P (i) are simultaneously emitted every unit time T1, T2, T2,. This is because the conventional technology emits only a single blinking light (information light).

  Thus, according to the optical transmitter 1 of this embodiment, the number of light emitting elements can be increased to N, and the information transmission amount can be increased N times.

Next, the optical receiver 6 used as a pair with the optical transmitter 1 will be described.
FIG. 3 is a configuration diagram of the optical receiver 6. In this figure, the optical receiver 6 includes N light receiving units 7 (i), a spread code generation circuit 8, N despreading units 9 (i), an information restoration circuit 10, and a synchronization circuit 11. The N light receiving units 7 (i) respectively receive N information lights P (i) emitted from the optical transmitter 1, binarize them, and output them.

  Each of the N light receiving units 7 (i) needs to individually receive N information lights P (i). That is, the first light receiving unit 7 (1) receives the first information light P (1), the second light receiving unit 7 (2) receives the second information light P (2), .. It is necessary to receive the Nth information light P (N) by the Nth light receiving portion 7 (N).

  However, such one-to-one light reception (separate light reception of a plurality of information lights) is, for example, that N pieces of information light P (i) have directivity like a light beam and are on the axis of the light beam. This is difficult unless certain conditions are met, such as the location of one light receiving unit at the same time. If the conditions are not met, multiple information lights will be received simultaneously by one light receiving unit. However, for convenience of explanation, the description will be continued assuming that N pieces of information light P (i) are received in a one-to-one relationship by the N pieces of light receiving units 7 (i). . A solution relating to the separation and reception of a plurality of information lights will be described in detail later.

  Now, the N light receiving sections 7 (i) are configured by photoelectric conversion elements that convert light intensity into electric signals. A typical example of such an element is a photodiode, but is not limited thereto, and may be a two-dimensional imaging device such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). This is because such a two-dimensional imaging device includes a large number of pixels arranged in a matrix in the matrix direction, and outputs an electrical signal corresponding to the intensity of light from each pixel.

  The spreading code generation circuit 8 generates N spreading codes C (i). The N spreading codes C (i) are also codes having a repetitive pattern different from the blinking pattern of disturbance light such as light in the natural world, and are generated by the spreading code generation circuit 8 of the optical transmitter 1. This is the same as the number of spreading codes C (i).

  Note that the N spreading codes C (i) generated by the spreading code generation circuit 8 may be generated individually, but in the present embodiment, as in the optical transmitter 1, the spreading codes to be held are In order to reduce the storage capacity of the memory and the like by reducing the number of the memory to one and reducing the cost, the N spreading codes C (i) are shifted while shifting the reference spreading code by a predetermined amount (for example, by 1 bit). ) Will be generated.

  A signal obtained by binarizing the information light P (i) and a spread code C (i) are input to the N despreading units 9 (i). The despreading unit 9 (i) compares the signal obtained by binarizing the information light P (i) with the spread code C (i), and if the phase of the two signals is the same, sets the logic “1”. If it is output and the phase is reversed, a logic “0” is output. That is, an operation (despreading) opposite to the N spreading units 4 (i) of the optical transmitter 1 is performed to generate a parallel signal RX (i) of N bits. The information restoration circuit 10 converts the parallel signal RX (i) into a serial signal sequence, and restores the reception information RX having the same content as the transmission information TX at the beginning. The synchronization circuit 11 is for synchronizing the generation period of the spreading code C (i) and the generation period of the transmission side spreading code (T1, T2, T3, T4,... In FIG. 2). .

  In summary, the optical receiver 6 of the present embodiment binarizes the N pieces of information light P (i) from the optical transmitter 1 individually by the N light receiving units 7 (i). The signal is converted into a signal, and the N despreading units 9 (i) perform the reverse operation of the N spreading units 4 (i) of the optical transmitter 1 to convert into the N-bit parallel signal RX (i). Further, the signal RX (i) is converted into a serial signal and output as reception information RX. Accordingly, since the reception information RX having the same contents as the transmission information TX can be restored, a relatively short-distance communication system using light, for example, product descriptions at stores, descriptions of exhibits at museums and exhibitions, land for buildings, etc. The present invention can be applied to a system such as visible communication that can be used for various purposes such as mark display, advertisement display, and amusement park congestion state display.

In order to put the above system into practical use, the above-described problem (separate light reception of a plurality of information lights) must be solved.
FIG. 4 is a configuration diagram of a main part of the optical receiver 6 that solves this problem. In the light receiving unit 7 (2), various unnecessary lights enter in addition to the information light P (2) that should be received. For example, adjacent information light P (1), P (3), other disturbance light Pa, etc. enter. The light receiving unit 7 (2) outputs a signal PJ (2) having a magnitude corresponding to a value (P (1) + P (3) + Pa) obtained by adding these lights. The signal PJ (2) is not a simple binary signal (1/0) but a multi-value analog signal with various amplitudes.

  The despreading unit 7 (2) includes an average value extraction circuit 12, a polarity switching circuit 13, an integration and sample hold (S / H) circuit 14 (integration circuit), and a binarization circuit 15. The average value extraction circuit 12 extracts only the direct current component and low frequency component of the signal RJ (2), and outputs them as a reference signal REF (2) to the polarity switching circuit 13 and the integration and sample hold circuit 14.

  The polarity switching circuit 13 is also supplied with the spreading code C (2) from the spreading code generating circuit 8, and the polarity switching circuit 13 has the spreading code C (2) = 1 with respect to the reference signal RJ (2). In this case, the spread code C (2) is output as it is as the signal RK (2), and when the spread code C (2) = 0, the spread code (C2) is inverted and output as the signal RK (2). The normal / inverted determination level is the reference signal REF (2).

  The integration and sample hold circuit 14 integrates the signal RK (2) (area integration during one sample hold period), samples and holds the integrated value, and outputs the signal RS (2) to the binarization circuit 15. The binarization circuit 15 converts the signal RS (2) into the binarization signal RX (2) and outputs it to the information restoration circuit 10, and the information restoration circuit 10 does not match the binarization signal RX (2). The other binarized signals RX (1), RX (3),... RX (N) are serially converted to restore the reception information RX having the same contents as the original transmission information TX.

  Here, unnecessary light other than the original information light P (2) (information light P (1), P (3), disturbance light Pa, etc.) is a stage of the output signal RS (2) of the integration and sample hold circuit 14. To be removed. This is because the spread code of the original information light P (2) is different from the spread codes of the other information lights P (1) and P (3), and the disturbance light Pa has the spread code itself. Because there is no.

In general, the spread gain GK in spread communication is given by equation (1).
GK = 20 LogM (dB) (1)
However, M is the number of bits of the spread code. The multiplex noise amount GN when the spread-modulated signal is multiplexed is given by equation (2).
GN = 20 LogN (dB) (2)
However, N is the multiplex number. Therefore, the noise margin GY in the spread multiplex communication is
GY = GK-GN (dB)
= 20LogM-20LogN
= 20 Log (M / N) (3)
However, when all multiplexed signals are at the same level, the number of spread code bits M = 7 and the number of information light N = 3 of this embodiment are substituted into this equation (3).
GY = 20Log (7/3)
= 7.3 (dB) (4)
It becomes. According to the configuration of the present embodiment, the expression (4) still has a margin of 7 dB or more. Therefore, unnecessary light (information light P (1)) other than the original information light P (2) is equivalent to the margin. , P (3) and disturbance light Pa, etc.) can be eliminated.

Next, another embodiment (second embodiment) for solving the above problem (separate light reception of a plurality of information lights) will be described.
FIG. 5 is a front external view of the optical transmitter 20 according to the second embodiment. In this figure, the optical transmitter 20 is configured by combining 3 × 3 boxes as one unit block and combining a plurality of blocks (six in the figure). Each box is a light emitting unit that emits information light into space. Therefore, the optical transmitter 20 in the illustrated example includes a total of 3 × 3 × 6 = 54, that is, N = 54 light emitting units.

  The character string in the box (alphabetic capital letter + two-digit number) has the following meaning. The first alphabetic capital letter (A to I) represents the type of spreading code. That is, in this example, nine types of spreading codes from the Ath spreading code (hereinafter referred to as CodeA) to the Ith spreading code (hereinafter referred to as CodeI) are used.

  The upper digit of the two-digit numerical value represents the block position, and the lower digit represents the position of the box (light emitting unit) in the block. Specifically, 00 represents a light emitting unit located on the upper left of the upper left block, 01 represents a light emitting unit located in the upper stage of the block, and 02 represents a light emitting unit located on the upper right of the block. , 03 represents a light emitting unit located in the middle left of the block, 04 represents a light emitting unit located in the middle of the block, 05 represents a light emitting unit located in the middle left of the block, and 06 represents the same block. The light emitting part located on the lower left of the block, 07 represents the light emitting part located in the lower part of the block, and 08 represents the light emitting part located on the lower left of the block.

  Similarly, 10 represents a light emitting unit located in the upper left of the upper middle block, 11 represents a light emitting unit located in the upper middle of the block, 12 represents a light emitting unit located in the upper right of the block, 13 Represents a light emitting part located in the middle left of the block, 14 represents a light emitting part located in the middle of the block, 15 represents a light emitting part located in the middle left of the block, and 16 represents a lower part of the block. A light emitting unit located on the left side, 17 represents a light emitting unit located in the lower stage of the block, and 18 represents a light emitting part located on the lower left side of the block.

  Similarly, 20 represents a light emitting unit located on the upper left of the upper right block, 21 represents a light emitting unit located in the upper stage of the block, 22 represents a light emitting unit located on the upper right of the block, 23 Represents a light emitting part located in the middle left of the block, 24 represents a light emitting part located in the middle of the block, 25 represents a light emitting part located in the middle left of the block, and 26 represents a lower part of the block. A light emitting unit located on the left side, 27 represents a light emitting unit located in the lower stage of the block, and 28 represents a light emitting part located on the lower left side of the block.

  Similarly, 30 represents a light emitting unit located on the upper left of the lower left block, 31 represents a light emitting unit located in the upper stage of the block, 32 represents a light emitting unit located on the upper right of the block, 33 Represents a light emitting part located in the middle left of the block, 34 represents a light emitting part located in the middle of the block, 35 represents a light emitting part located in the middle left of the block, and 36 represents a lower part of the block. A light emitting unit located on the left side, 37 represents a light emitting unit located in the lower stage of the block, and 38 represents a light emitting part located on the lower left side of the block.

  Similarly, 40 represents a light emitting part located on the upper left of the lower middle block, 41 represents a light emitting part located in the upper part of the block, 42 represents a light emitting part located on the upper right of the block, 43 Represents a light emitting part located in the middle left of the block, 44 represents a light emitting part located in the middle of the block, 45 represents a light emitting part located in the middle left of the block, and 46 represents a lower part of the block. A light emitting unit located on the left side, 47 represents a light emitting unit located in the lower stage of the block, and 48 represents a light emitting part located on the lower left side of the block.

  Similarly, 50 represents a light emitting unit located on the upper left of the lower right block, 51 represents a light emitting unit located in the upper stage of the block, 52 represents a light emitting unit located on the upper right of the block, 53 Represents a light emitting part located in the middle left of the block, 54 represents a light emitting part located in the middle of the block, 55 represents a light emitting part located in the middle left of the block, and 56 represents a lower part of the block. A light emitting unit located on the left side, 57 represents a light emitting unit located in the lower stage of the block, and 58 represents a light emitting part located on the lower left side of the block.

  Thus, the illustrated optical transmitter 20 includes 54 light emitting units, and 54 information lights modulated by nine types of spreading codes CodeA to CodeI are simultaneously emitted from each of these light emitting units to space. To do. Hereinafter, these information lights are identified by character strings (A00, A01,...) In the box.

  FIG. 6 is an external view of an optical receiver 21 used as a pair with the optical transmitter 20 described above. Here, although a general-purpose digital camera is used for the optical receiver 21, the present invention is not limited to this. Any imaging device including a two-dimensional imaging device such as a CCD or CMOS may be used. More specifically, 54 pieces of information light modulated by nine types of spreading codes CodeA to CodeI may be a pixel unit or a group of a plurality of pixels. Any imaging device may be used as long as it is capable of receiving light and having a signal processing function capable of individually processing the received light signals.

  Although not particularly limited, the optical receiver 21 includes a retractable lens barrel 23, a strobe light emission window 24, a finder front window 25, a sound collection hole 26 for recording, and the like on the front surface of a body 22 having a shape suitable for holding. At the same time, a shutter button 27 and a power switch 28 for photographing are arranged on the upper surface of the body 22, and further, a loudspeaker 29 for sound output, a finder rear window 30, a mode switch 31, and a zoom operation are disposed on the rear surface of the body 22. A switch 32, a MENU button 33, a cursor key 34, a SET button 35, a DISP button 36, a liquid crystal monitor 37, and the like are arranged. In addition, a cover 38 is provided on the bottom surface of the body 22, and the cover 38 is opened to open the body 22. Large capacity such as battery 39, card-type memory or card-type hard disk installed inside Department has a memory 40 to be detachable.

  FIG. 7 is an internal block diagram of the optical receiver 21. In this figure, the optical receiver 21 can be classified into an audio input system 41, an imaging system 42, a control system 43, an audio output system 44, an image storage system 45, a display system 46, an operation system 47, and the like for each function. it can.

  Explaining each of these systems, the audio input system 41 is amplified by a microphone 48 disposed behind the sound collection hole 26 on the front surface of the body, an amplifier 49 that amplifies the sound picked up by the microphone 48, and the amplifier 49. A / D converter 50 for converting the analog audio signal into a digital signal, and an audio memory 51 for temporarily storing the digitally converted audio signal.

  The imaging system 42 includes a photographic lens group 52 with a zoom function and an autofocus function housed in a lens barrel 23 in front of the body, and a CCD that converts a subject image that has passed through the photographic lens group 52 into a two-dimensional image signal. A two-dimensional imaging device 53 composed of, for example, a CMOS, a video processing unit 54 for performing required image processing on an image signal from the two-dimensional imaging device 53, and an image signal after the image processing are temporarily recorded. An image memory 55, a focus driving unit 56 for driving a focus mechanism (not shown) of the lens barrel 23, a zoom driving unit 57 for driving the zoom mechanism, and a strobe light emission window 24 on the front surface of the body. A strobe 58, a strobe driving unit 59 that drives the strobe 58, and each of these units (two-dimensional imaging device 53, video processing unit 54, photo Comprising Kas driver 56, a zoom driving unit 57, an imaging controller 60 for controlling the flash driving unit 59).

  The control system 43 is necessary for the operation of the control circuit 61 and the control circuit 61 (matching means) using a one-chip microprocessor that controls each system described above to control the operation of the optical receiver 21 in a concentrated manner. A program memory 62 for storing various programs in a nonvolatile manner and a user data memory 63 for storing user-specific data in a nonvolatile and rewritable manner are provided.

  The audio output system 44 includes a D / A converter 64 that converts audio data appropriately output from the control circuit 61 into an analog audio signal, an amplifier 65 that amplifies the audio signal, and amplifies the amplified audio signal. For this purpose, a speaker 66 is provided near the loudspeaker hole 29 on the back of the body.

  The image storage system 45 includes a memory input / output unit 67 that writes image data, audio data, or other data to the external memory 40, or reads the data from the external memory 40, and an external memory 40 that stores these data in a rewritable manner. Is provided.

  The display system 46 converts display data appropriately output from the control circuit 61 into a predetermined display format (display format adapted to the resolution of the liquid crystal monitor 37), and an output signal from the display control unit 68. A liquid crystal monitor 37 provided on the back of the body is provided for display.

  The operation system 47 includes an operation input unit 69 including a shutter button 27 on the upper surface of the body, a mode switching switch 31 on the rear surface, a zoom operation switch 32, a MENU button 33, a cursor key 34, a SET button 35, a DISP button 36, and the like. And an input circuit 70 for inputting an operation signal from the input unit 69 to the control circuit 61.

  FIG. 8 is an enlarged view of the imaging surface of the two-dimensional imaging device 53. In this figure, a large number of cells arranged in a matrix in the row direction and the column direction schematically represent the pixels arranged on the imaging surface of the two-dimensional imaging device 53. When the focus is appropriate, the light from the subject that has passed through the photographic lens group 52 is focused on the imaging surface, and thus a subject image is projected (formed) on the imaging surface. Each pixel (each cell) on the imaging surface generates and outputs an electrical signal (pixel signal) corresponding to the intensity of light irradiated on its own pixel area. The two-dimensional imaging device 53 reads out these pixel signals line-sequentially and outputs them as one image signal. Therefore, for example, when the number of pixels on the imaging surface is 640 × 480, one image signal is composed of 640 × 480 pixel signals.

  FIG. 9 is a diagram illustrating an operation flowchart of the optical receiver 21. When the power switch 28 of the optical receiver 21 is turned on, the current position of the mode switch 31 is checked to determine whether it is in the playback mode or the shooting mode (step S11). In the case of “reproduction mode”, predetermined “reproduction mode processing” is executed (step S12). The reproduction mode processing is a mode in which photographed image data is read from the external memory 40 and is reproduced and displayed on the liquid crystal monitor 47.

  On the other hand, in the “shooting mode”, first, it is determined whether or not “optical communication” is performed (step S13). Optical communication refers to receiving a large amount of optical information from the optical transmitter 20 (see FIG. 5), restoring the information, and displaying it on the liquid crystal monitor 47. When the user wants to perform optical communication, the mode changeover switch 31 is set to the “shooting mode” position, and a predetermined button operation (for example, the cursor key 34 is pressed a predetermined number of times in a predetermined direction, then the SET is performed). Operation such as pressing the button 35).

  When optical communication is not performed, “normal photographing mode processing” is executed (step S14). In normal shooting mode processing, the composition is adjusted while viewing the through image displayed on the LCD monitor 47, and when the desired composition is obtained, the shutter button 27 is depressed to perform shooting, and the shooting data is taken. This is a mode in which a series of processes of compressing and recording in the external memory 40 is executed.

  When optical communication is performed, the user directs the lens barrel 23 toward the object (the optical transmitter 20 in FIG. 5) in the “shooting mode” state so that the entire object can be accommodated on the liquid crystal monitor 47. Adjust the composition. At this time, if the entire object does not fit on the liquid crystal monitor 47 or is too small, the zoom operation switch 32 is adjusted to widen the shooting field angle (widen) or narrow (to telephoto). May be.

  When an appropriate composition is obtained, when a user performs a predetermined button operation (for example, an operation such as pressing the SET key 35 after pressing the cursor key 34 in a predetermined direction for a predetermined number of times) A matching process is performed (step S15: matching means), information is then read from the object (the optical transmitter 20 in FIG. 5) (step S16), and finally the information is displayed on the liquid crystal monitor 47 (step S16). Step S17).

  The matching process is to solve the previous problem (separate reception of a plurality of information lights). That is, the optical transmitter 20 in FIG. 5 has a large number (54 in the illustrated example) of light emitting units arranged on a plane, while the optical receiver 21 also has a number of pixels arranged in a matrix. Although the two-dimensional imaging device 53 is provided, the number and arrangement of the light emitting units and the number and arrangement of the pixels of the two-dimensional imaging device 53 are naturally not the same, and the optical transmitter 20 receives the optical receiver. This is because the optical receiver 21 requires some processing for performing “separated light reception of a plurality of information beams”.

  FIG. 10 is a diagram illustrating the distance from the optical transmitter 20 to the optical receiver 21. In this figure, it is assumed that users 71 to 77 having the optical receiver 21 are standing at respective positions away from the optical transmitter 20 by distances L1, L2, L3, L4, L5, L6, and L7. It is assumed that all the users 71 to 77 are aware of the blinking of the optical transmitter 20 and know that the blinking of the light is optical communication including arbitrary information. Now, assuming that all users 71 to 77 point their own optical receivers 21 toward the optical receivers 21 and perform predetermined button operations to start optical communication, the liquid crystal monitors 47 of the optical receivers 21 of the respective persons are used. In this case, images having different sizes according to the distances L1 to L7 are displayed.

  The size of the projected image is the largest at the distance L1, gradually decreases as the distances L2, L3, L4,... And the smallest at the distance L7. Here, in order to simplify the description, the zoom operation is not performed.

  FIG. 11 is a relationship diagram between the light emitting unit of the optical transmitter 20 and the pixels of the optical receiver 21 at the distance L1. As shown in (a), the light information of the upper left light emitting part is “A00”, the light information of the upper light emitting part is “B01”, the light information of the upper right light emitting part is “C02”, the middle left The light information of the light emitting part is “D03”, the light information of the light emitting part in the middle stage is “E04”, the light information of the light emitting part of the middle right is “F05”, the light information of the light emitting part of the lower left is “G06”, the lower part It is assumed that the light information of the light emitting part in the middle is “H07” and the light information of the light emitting part on the lower right is “I08”. That is, it is assumed that each light emitting unit is modulated with nine different spreading codes (Code A to Code I). Here, CodeA is a spreading code that serves as a reference in the matching process.

  At the distance L1 closest to the optical transmitter 20, the two-dimensional imaging device 53 of the optical receiver 21 images all the light emitting units of the optical transmitter 20 with a sufficient size. For this reason, as shown in (b), in the image photographed by the two-dimensional imaging device 53, a cluster of detection pixels D of CodeA among non-detection pixels U of CodeA (3 × 3 pixels in the illustrated example) Will exist. In such a case, the center of the detection area D is set as the sampling point of Code A, and the sampling point of Code B, the sampling point of Code C, the sampling point of Code D,... Just go.

  FIG. 12 is a relationship diagram between the light emitting unit of the optical transmitter 20 and the pixels of the optical receiver 21 at the distance L2. In this figure, at a distance L2 slightly farther than the distance L1, the cluster of detection pixels D of CodeA is smaller than that at the distance L1. For example, as shown in (b), it may be about 2 × 2 pixels. The CodeA sampling point exists somewhere in this narrow range (a range of about 2 × 2 pixels), but there is little information and it is difficult to determine a reliable CodeA sampling point. Therefore, in such a case, the center of one pixel out of 2 × 2 pixels (for example, a pixel completely covered with hatching) is used as a temporary CodeA sampling point, and this temporary sampling point is the starting point. Then, the CodeB sampling point, the CodeC sampling point, the CodeD sampling point,... Are determined in sequence. If these sampling points are used and there are many errors, the provisional sampling point is moved to another detection pixel D and the above operation is repeated.

  FIG. 13 is a relationship diagram between the light emitting unit of the optical transmitter 20 and the pixels of the optical receiver 21 at the distance L3. At a distance L3 farther than the distance L2, one light emitting unit and one pixel may correspond one to one. In such a case, the center of each detection pixel D is set as the sampling point of Code A, and the sampling point of Code B, the sampling point of Code C, the sampling point of Code D,... Are sequentially determined starting from the sampling point of Code A. Do it.

  FIG. 14 is a relationship diagram between the light emitting unit of the optical transmitter 20 and the pixels of the optical receiver 21 at the distance L4. At a distance L4 farther than the distance L3, as shown in (b), the appearance ratio of the detection pixel D of CodeA and the non-detection pixel U of CodeA may be 1: 3 in the row direction. In this case, the ratio of the light emitting portion to the pixel is 2 to 3 in the row direction, and the sampling point of CodeA is given by the hatching center of the detection pixel D. Therefore, the sampling of CodeB is sequentially performed starting from the sampling point of CodeA. A point, a sampling point for CodeC, a sampling point for CodeD, and so on may be determined.

  FIG. 15 is a relationship diagram between the light emitting unit of the optical transmitter 20 and the pixels of the optical receiver 21 at the distance L5. At a distance L5 that is farther than the distance L4, the ratio between the detection pixel D of CodeA and the non-detection pixel U may be 2 to 1 in the row direction. In this case, the ratio between the light emitting portion and the pixel is 1 to 2 in the row direction, and the sampling point of CodeA is given by the hatching center of the detection pixel D. Therefore, the sampling of CodeB is sequentially performed starting from the sampling point of CodeA. A point, a sampling point for CodeC, a sampling point for CodeD, and so on may be determined.

  FIG. 16 is a relationship diagram between the light emitting unit of the optical transmitter 20 and the pixels of the optical receiver 21 at the distance L6. At a distance L6 farther than the distance L5, all the pixels may become the detection pixels D of CodeA. In this case, all the spreading codes (Code A to Code I) are correlated with each pixel. In the case of the distance L7 further far than the distance L6, the same relationship as in FIG. 16 is obtained. However, in this case, since the adjacent repeated pattern enters each pixel, it is treated as unreproducible (for example, Display an error message and notify the user).

  FIG. 17 is a diagram illustrating a flowchart of the matching process. In this figure, when the matching process is started, first, the reference spreading code (Code A) is matched in all pixels (step S15a). Then, it is determined whether or not there is a continuous detection region D in the non-detection region U (step S15b). If it does not exist, the degree of overlap is calculated from the ratio of the non-detection region U and the detection region D. (Step S15c), a matching pattern is selected based on the calculation result (Step S15d).

  On the other hand, if there is a continuous detection region D in the non-detection region U, it is next determined whether or not the ratio between the non-detection region U and the detection region D is an expected ratio ( In step S15e, if the expected ratio is reached, the center of the detection area D is set as a matching point of Code A (step S15f), and the matching point of another code is determined using the matching point as a starting point (step S15g). Alternatively, if the ratio is not as expected, one of the pixels in the detection region D is set as a matching point of Code A (step S15h), and a matching point of another code is determined using the matching point as a starting point (step S15i). .

  As described above, according to the second embodiment, the reference spread code (Code A) pixel (detection pixel D) from the captured image of the optical transmitter 20 captured by the two-dimensional imaging device 52 of the optical receiver 21. In accordance with the detection result, the sampling point of CodeA is determined, and the sampling points of other spreading codes (CodeB to CodeI) are sequentially determined starting from the sampling point of CodeA. The information from the optical transmitter 20 can be restored and reproduced by the optical receiver 21 by correctly separating and identifying a plurality of information lights regardless of the distance (between L1 and L6). Therefore, for example, optical transmitters that can be used for various purposes such as product descriptions at stores, descriptions of exhibits at museums and exhibitions, landmark displays for buildings, advertisement displays, play facilities congestion status displays such as amusement parks, The optical receiver and the optical communication system can be put to practical use.

It is a block diagram of the optical transmitter 1 of 1st Embodiment. 3 is a signal time sequence diagram of the optical transmitter 1. FIG. It is a block diagram of the optical receiver 6 of 1st Embodiment. It is a principal part block diagram of the optical receiver 6 which enabled the separate light reception of the some information light. It is a front external view of the optical transmitter 20 of the second embodiment. 1 is an external view of an optical receiver 21 used in a pair with an optical transmitter 20. FIG. 3 is an internal block diagram of the optical receiver 21. FIG. 3 is an enlarged view of an imaging surface of a two-dimensional imaging device 53. FIG. FIG. 6 is a diagram illustrating an operation flowchart of the optical receiver 21. FIG. 3 is a diagram illustrating a distance from an optical transmitter 20 to an optical receiver 21. FIG. 4 is a relationship diagram between a light emitting unit of the optical transmitter 20 and a pixel of the optical receiver 21 at a distance L1. FIG. 4 is a relationship diagram between a light emitting unit of the optical transmitter 20 and a pixel of the optical receiver 21 at a distance L2. FIG. 6 is a relationship diagram between a light emitting unit of the optical transmitter 20 and a pixel of the optical receiver 21 at a distance L3. FIG. 4 is a relationship diagram between a light emitting unit of the optical transmitter 20 and a pixel of the optical receiver 21 at a distance L4. FIG. 6 is a relationship diagram between a light emitting unit of the optical transmitter 20 and a pixel of the optical receiver 21 at a distance L5. FIG. 6 is a relationship diagram between a light emitting unit of the optical transmitter 20 and a pixel of the optical receiver 21 at a distance L6. It is a figure which shows the flowchart of a matching process.

Explanation of symbols

C (i) Spread code P (i) Information light S15 Step (matching means)
TX transmission information 1 Optical transmitter 2 Multi-level circuit 3 Spread code generator 4 (i) Spreader 5 (i) Light emitter 6 Optical receiver 7 (i) Light receiver 8 Spread code generator 9 (i) Despread Unit 10 Information Restoration Circuit 12 Average Value Extraction Circuit 13 Polarity Switching Circuit 14 Integration and Sample and Hold Circuit (Integration Circuit)
15 Binarization circuit 53 Two-dimensional imaging device 61 Control circuit (matching means)
21 Optical receiver

Claims (7)

A multi-value conversion circuit that multi-values transmission information by dividing it into N bits;
A spreading code generator for generating N spreading codes;
N spreading units that output and reversely output a spreading code corresponding to the logic of each bit of the multi-valued transmission information;
An optical transmitter comprising: N light emitting units driven by signals from each diffusion unit. N light receiving units that receive N information light and convert them into electrical signals;
A spreading code generator for generating N spreading codes;
N despreading units that output a logic 0 or logic 1 signal based on the phase relationship between the electrical signals output from each of the N light receiving units and N spreading codes, and the N despreading units An optical receiver comprising: an information restoration circuit that restores received information by combining the outputs of. The N despreading units are:
An average value extraction circuit that extracts a direct current component and a low frequency component of a signal from the light receiving unit and generates a reference signal composed of the direct current component and the low frequency component;
When the signal from the light receiving unit, the spread code from the spread code generation circuit and the reference signal are input, the spread code is output as it is when the spread code is larger than the reference signal, and when the spread code is smaller than the reference signal A polarity switching circuit for inverting and outputting the spreading code;
An integration circuit that integrates the signal from the polarity switching circuit and outputs a sample hold value of the integration value;
The optical receiver according to claim 2, further comprising: a binarization circuit that binarizes an output of the integration circuit. The N light receiving units are N pixels arranged on an imaging surface of a two-dimensional imaging device, and detect a pixel of a reference diffusion code from a photographed image photographed by the two-dimensional imaging device. And a matching means for determining a sampling point of the reference spreading code according to the detection result and sequentially determining sampling points of other spreading codes starting from the sampling point of the reference spreading code. The optical receiver according to claim 2 or 3. An optical communication system comprising the optical transmitter according to claim 1 and the optical receiver according to any one of claims 2 to 4. 2. The optical transmitter according to claim 1, wherein the spread code generator generates N spread codes while shifting a reference spread code by a predetermined amount. 3. The optical receiver according to claim 2, wherein the spreading code generating unit generates N spreading codes while shifting a reference spreading code by a predetermined amount.

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