WO2019235870A1

WO2019235870A1 - Optical signal transmission device and optical signal communication device

Info

Publication number: WO2019235870A1
Application number: PCT/KR2019/006859
Authority: WO
Inventors: 배점한
Original assignee: 숭실대학교산학협력단
Priority date: 2018-06-08
Filing date: 2019-06-07
Publication date: 2019-12-12

Abstract

An embodiment provides an optical signal transmission device comprising: a light source unit including at least one light source element; and a driving unit for controlling the operation of the light source element to output an optical signal, wherein the driving unit generates the light signal distinguishably including a first frame including a first data code and a first start code inserted into a start point of the first data code and a second frame including a second data code and a second start code inserted into a start point of the second data code, and alternately outputs the first frame and the second frame to control the operation of the light source element.

Description

Optical signal transmission device and optical signal communication device

One embodiment of the present invention relates to an optical signal transmission device and an optical signal communication device, and an optical signal transmission device and an optical signal communication device that can be applied to Internet of Things (IoT) technology and various optical communication technologies.

As unmannedness progresses, the need for things to express their own information increases. It can be convenient if you can get information about products in unmanned households through simple communication methods, or get information about products directly from objects in the exhibition hall. It is also useful if you can use a popular smartphone as a data receiver. On the other hand, there are methods such as RFID, QR Code, and Bar Code, but RFID requires a separate receiving device, and QR Code or Bar Code can provide only a predetermined amount of Code. There is a precondition that a tag must be attached to an object. However, camera communication uses a smartphone as a receiving device, and the data rate is about 1Kbit / sec, but can contain a large amount of guidance information. In addition, it is used in the form of a sign because power must be delivered to a light emitting device (LED).

Conventional modulation methods include OOK (On-Off Keying), MFSK (Multi Frequency Shift Keying), UFSOOK (Under-sampled Frequency Shift On-Off Keying), UPSOOK (Under-sampled Phase Shift On-Off Keying), Color Methods such as transmission were introduced.

The MFSK method using frequency is to correspond to a relatively long distance. Since the frequency is created by using several black and white bands, the data transmission rate is low as low as 12 Byte / sce and the receiving distance is long as several meters. UFSOOK and UPSOOK have a distance of several meters and have a very low data rate of about 1 bit / frame.

The short-range OOK method uses RLL codes such as Manchester Code, 4B6B, and 8B10B. When decoding the data, a method of decoding the data in the forward direction (future) and the backward direction (past) on the time axis with respect to the SF (Start Frame) signal was used. The data is decoded by dividing each of the SF pulse edges at predetermined time intervals. However, there is a high probability of error when the ratio of 1 and 0 is asymmetry. In addition, when decoding in the past temporal direction of SF, there is a problem in that it does not correspond to the non-uniformity of the idle period of the image sense or the exposure time of the image sense.

In addition, the pulse position modulation (PPM) method of the infrared remote controller is a one-dimensional signal with respect to time, and discontinuity does not occur in the middle of the transmitted signal. However, a camera is a three-dimensional signal in which a two-dimensional image frame continues over time. In addition, there is a problem that discontinuity occurs depending on the asynchronous relationship between transmission and reception and time.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide an optical signal transmission device and an optical signal communication device to which a modulation method and structure of a short range low power camera communication is applied.

Another object of the present invention is to provide an optical signal transmission device and an optical signal communication device capable of completely avoiding an idle interval of an image sense and a discontinuity of a camera exposure time.

Another object of the present invention is to provide an optical signal transmission device and an optical signal communication device that do not require separate clock information because the width of the pulse indicates data.

In addition, the transceiver is simple to provide an optical signal transmission device and an optical signal communication device suitable for IoT.

Another object of the present invention is to provide an optical signal transmission device and an optical signal communication device that can be utilized at a non-standard level for avoiding interference of radio waves or for local IoT communication.

According to an embodiment, the light source unit including at least one light source element; And a driving unit controlling the driving of the light source element to output an optical signal, wherein the driving unit includes a first start code inserted into the first data code and a start point of the first data code. A first frame and a second frame including a second data code and a second start code inserted into a start point of the second data code are generated and separated, and the first frame and the second frame are alternately outputted An optical signal transmission apparatus for controlling the driving of the light source element is provided.

The first start code and the second start code may be composed of different codes.

A plurality of start codes and data codes may be repeatedly inserted into a single frame of each of the first frame and the second frame.

Parity bits may be added to the last bits of the first data code and the second data code.

The first data code and the second data code may represent data according to a row interval pulse width.

A gap code for classifying a frame may be added between the first data code and the second data code.

According to an embodiment of the present invention, there is provided an optical signal transmitting apparatus including a light source unit including at least one light source element, and a driving unit controlling the driving of the light source element to output an optical signal, and an optical signal receiving apparatus receiving the optical signal. The driving unit may include a first frame including a first start code inserted into the first data code and a start point of the first data code, and a start point of the second data code and the second data code. Provided is an optical signal communication apparatus for generating a second frame including a second start code inserted into the second frame, and alternately outputting the first frame and the second frame to control the driving of the light source element.

The optical signal receiving apparatus may include an image sensor detecting the optical signal; A photoelectric conversion unit converting the detected optical signal into an electrical signal; And a decoding unit for decoding the converted electrical signal.

The decoding unit may perform synchronization using the first start code and the second start code.

When the decoding unit decodes a data code in an arbitrary frame, the decoding unit may not perform decoding on the detected optical signal until the start code of a frame different from the corresponding frame is detected.

The optical signal transmission device and the optical signal communication device of the present invention can completely avoid the discontinuity of the idle interval and the camera exposure time of the image sense.

In addition, since the width of the pulse represents data, no separate clock information is required.

In addition, the transceiver is simple and suitable for IoT.

It can also be used at non-standard stages to avoid radio interference or for local IoT communication.

1 is a conceptual diagram of an optical signal communication apparatus according to an embodiment.

2 is a block diagram of an optical signal transmission apparatus according to an embodiment.

3 is a block diagram illustrating an optical signal receiving apparatus according to an embodiment.

4 is a diagram for describing a start code according to an embodiment.

5 and 6 are diagrams for describing an even frame and an odd frame according to an embodiment.

7 to 9 are diagrams for describing an optical signal reception result according to an embodiment.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated and described in the drawings. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms including ordinal numbers, such as second and first, may be used to describe various components, but the components are not limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the second component may be referred to as the first component, and similarly, the first component may also be referred to as the second component. The term and / or includes a combination of a plurality of related items or any item of a plurality of related items.

When a component is said to be "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that another component may be present in the middle. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present disclosure does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings, and the same or corresponding components will be given the same reference numerals regardless of the reference numerals, and redundant description thereof will be omitted.

1 is a conceptual diagram of an optical signal communication device 1 according to an embodiment, FIG. 2 is a block diagram of an optical signal transmission device 10 according to an embodiment, and FIG. 3 is an optical signal receiving device 20 according to an embodiment. ) Is a block diagram of the configuration.

1 to 3, an optical signal communication device 1 according to an embodiment includes an optical signal transmission device 10 and an optical signal reception device 20. The optical signal transmission apparatus 10 may be embedded in various objects or mounted in a separate module form to output an optical signal. The optical signal receiving device 20 is equipped with an image sensor for detecting an optical signal, and may be implemented in various terminal forms such as a smart phone, a PDA, a notebook computer, and the like.

The optical signal transmitting apparatus 10 includes a light source unit 11 and a driver 12.

The light source unit 11 may include at least one light source element. The light source unit may be implemented in a structure in which a plurality of light source elements are arranged. For example, the light source unit 11 may be implemented in a structure in which four light source elements having a length of 3.5 cm are arranged. However, the present invention is not limited thereto, and the number, size, arrangement, and the like of the light source elements may be variously modified according to the reception distance, sensitivity, light quantity, etc. of the optical signal.

The driver 12 may output the optical signal by controlling the driving of the light source element. The driver 12 may include a clock unit 14 for controlling the output of the optical signal and an encoding unit 13 for generating the optical signal.

The encoding unit 13 includes an optical signal at a first frame including a first data code and a first start code inserted at a start point of the first data code, and at a start point of the second data code and the second data code. It may be generated by dividing into a second frame including a second start code to be inserted. The optical signal may consist of 30 frames / sec. The length of a single frame is 33 ms, and 1T (Time Interval) represents a minimum unit pulse width.

The clock unit 14 may alternately output the first frame and the second frame to control the driving of the light source element.

The first start code of the first frame and the second start code of the second frame may be composed of different codes. For example, the first start code may be configured to include a high signal "1" for 2T followed by a low signal "0" for 1T. For example, the second start code may comprise a "1" which is a high signal for 3T. In an embodiment, the high signal is a signal for turning on the light source unit and the low signal is a signal for turning off the light source unit. Since the characteristics of the channel are obtained from "1" and "0", when the widths of the images are asymmetry with each other, when the start code contains 1 and 0 together, it can be usefully used as a reference signal.

The data code is contiguous with the start code. The first data code and the second data code may represent data according to a row interval pulse width.

A plurality of start codes and data codes may be repeatedly inserted into each single frame of the first frame and the second frame. If the start code and the data code are defined as one data code set, a plurality of data code sets may be repeatedly represented in a single frame. This repeatability is intended to compensate for the occurrence of errors due to the asynchronous and discontinuous characteristics of the optical signal communication device. For example, four or more data code sets may be repeatedly inserted in a single frame. That is, a single frame outputs four or more sets of data codes to represent one data. Since the optical transmitter and the optical receiver are in an asynchronous relationship, the data is repeated twice, and since the exposure time in a single frame is part of the frame period, the data is repeatedly output again and outputted twice to generate the data. The problem of discontinuity can be avoided.

In addition, each frame may include a dummy code. Dummy codes, unlike start codes and data codes, do not have information and allow a uniform distribution of data code sets within a single frame. For example, the dummy code may be configured to include a high signal "1" for 1T followed by a low signal "0" for 1T.

Next, the optical signal receiving device 20 may include an image sensor 21, a photoelectric converter 22, and a decoder 23.

The image sensor 21 may detect an optical signal.

The photoelectric conversion unit 22 may convert the detected optical signal into an electrical signal.

The decoding unit 23 may decode the converted electrical signal.

The decoding unit 23 may perform synchronization using the first start code and the second start code. The decoder 23 may receive the first frame and the second frame by using the first start code and the second start code. In the case of the optical signal, the synchronization between the transmitting device and the receiving device is not performed. Since the optical signal according to the embodiment has a structure in which the first frame and the second frame alternately transfer information, the decoding unit 23 detects the first start code and the second start code, each consisting of different codes, and thus the first frame. The frame and the second frame can be distinguished.

If the decoding unit 23 decodes the data code in an arbitrary frame, the decoding unit 23 may not perform decoding on the detected optical signal until the start code of the frame different from the corresponding frame is detected. A single frame signal contains a plurality of data code sets. Therefore, if the data code for a single frame is decoded, another data code included in the frame is a signal representing the same information, and thus an error may occur if the decoding is repeatedly performed. Accordingly, when the data code is decoded in the first frame, the decoding unit 23 does not decode the detected optical signal until the second start code of the second frame is detected. Alternatively, when the data code is decoded in the second frame, decoding is not performed on the detected optical signal until the first start code of the first frame is detected.

The decoding unit 23 may determine a pulse after a predetermined length from the start code as a dummy code and exclude it from the decoding target. That is, when the length of the data code is 4T at maximum, the decoding unit 23 determines that the signal detected between the data code and the start code is a dummy code and decodes if a new start code is not detected after 4T after the start code. Do not perform.

4 is a diagram for describing a start code according to an embodiment. In the following embodiment, the first frame is an even frame, and the second frame is an odd frame. The even and odd frames are alternately output. When receiving an optical signal it is necessary to know the beginning of the data and the order of the data. In addition, since transmission and reception are asynchronous, it is necessary to distinguish between even and odd frames. However, since the video signal is a continuous signal and the periods of the transmitting device and the receiving device are the same, both the start and the order of the data can be known as long as there is a code for distinguishing even and odd frames. Therefore, a start code for distinguishing even and odd frame signals is inserted. In Fig. 4, the thick line waveform is the start code and the rest is the data code. Start code uses code that is not used in data code. Two types of code are used for even and odd frames. The start code of an even frame is “1” for 2T and “0” for 1T. The start code of the odd frame is “1” for 3T.

A start code according to another embodiment may be used. According to this, the start code of the even frame can be set to "1" for 3T and to "0" for 1T. The start code of the odd frame may be set to "1" for 3T and to "0" for 2T. According to another embodiment, since the start bit of the start code always starts with " 1 " for 3T, the signal is uniform and can be advantageous in asymmetrical characteristics. However, the length of the cord is as long as 3T in total.

When the widths of the resultant images obtained from 1 and 0 are asymmetry with each other, when the start code contains 1 and 0 together, it can be usefully used as a reference signal.

5 and 6 are diagrams for describing an even frame and an odd frame according to an embodiment. Referring to FIG. 5, the data code may represent a 2-bit signal. Each data code is inserted after the start code. Each single frame repeatedly outputs the data code set including the start code and the data code four or more times.

"0" of the data code is represented by a low signal for 1T. "1" is represented by "0" for 2T. "11" is represented by "0" for 3T. The data value depends on where the pulse is located after the start code. According to the data code of the embodiment, the difference in the lengths of the codes "00", "01", "10" and "11" is minimized. When decoding, only the length between pulses needs to be measured, eliminating the need for complicated steps to restore the clock. In addition, data is repeatedly transmitted to avoid discontinuities due to camera exposure time or asynchronous transmission and reception.

The output of the optical signal is repeated four or more times in a combination of a start code and a data code. Because transmission and reception are asynchronous, they need to be duplicated twice, and again because exposure time is part of the frame period in one frame. This can avoid the problem of discontinuity of the optical signal. Therefore, the optical signal transmitting apparatus outputs the data code set four or more times in one frame period, so that the optical receiving apparatus can safely receive data in every frame without error.

In addition, a parity bit may be added to the last bit of the data code. Since the start code and the data code are repeated four or more times, if there is a parity error in the current code, the data that follows can be detected. In the embodiment, the parity bit may be used as useful information because the frame type is a repetitive code.

At the end of the frame where data transmission is completed, Idle state should be kept as "0". This is because maintaining an idle state of "1" can overlap the startup code. Between the frame and the frame can maintain the state of the "0" bit.

Alternatively, a gap code may be defined and added between the frame and the frame. The gap code may play a role of separating the frame from the frame. The gap code can be defined as "0" for 4T. "0" of 4T is a code not used in the embodiment. That is, if "0" appears for 4T, it can be confirmed that it is the beginning of the frame. When decoding the data, a lot of state machines are used. In this case, a gap code indicating the beginning of a frame may be an important reference signal.

In addition, the data code is preferably distributed uniformly throughout the entire frame time interval. This is because which section of the frame may match the exposure time section of the optical receiving device. Therefore, a dummy code such as a dotted line is added to spread the data code evenly over the entire frame section. In a single frame after the start code, only the specified code length is decoded and the remaining data codes are ignored. Transmission of the optical signal consists of repetition of even-> odd-> even frames. If the code is transmitted as “00_11_01_10”, it is transmitted in order of 0th frame Even_00, 1st frame Odd_11, 2nd frame Even_01, 3rd frame Odd_10.

7 to 9 are diagrams for describing an optical signal reception result according to an embodiment. Referring to FIG. 7, the modulation result of the optical signal received by the optical receiver is shown. The optical transmission device repeatedly transmits an optical signal in the order of Even_01, Odd_01, Even_10, Odd_10, Even_11, Odd_11, Even_00, Odd_00 and again in the order of Even_01, Odd_01, Even_10, Odd_10. The result of FIG. 7 is a result of observing the image of the light detected by the optical receiving apparatus after turning one frame. The right side of the data image is a tape measure to measure the length of the pulse. The starting point of the tape measure is shown in line with the starting point of the starting code. The optical receiving apparatus starts decoding when the start code is detected, and decodes only the data code consecutive to the first detected start code when the start code is detected in the corresponding frame. For example, after receiving the data code as the start code of the odd frame, it is ignored since the start code of the subsequent odd frame is a duplicate code and is accepted as new data when the start code of the even frame is received. With this rule, when data was checked at any time, the data was correctly received without loss. In the experiment, 2bit / frame was transmitted to determine the number of logic cases.

As shown in FIG. 7, the received image has room for subdividing pulses. Therefore, a test was performed by replacing an 8-bit data code in place of a 2-bit data code, and the results are shown in FIGS. 8 and 9.

Referring to Fig. 8, it is a result of experimenting when the on-off of the optical transmission device is accelerated. As the frequency increases, the ratio of white increases, and when the on-off reaches about 150us, the black band disappears and only white remains. This phenomenon appears to include both the on-off switching characteristics of the optical transmission device and the nonlinear characteristics of the optical reception device image sensor. In FIG. 7, the length of the 1T image of “0” or the 1T image of “1” is 1: 1 without significant difference. However, in Figs. 8 and 9 in which the 2-bit data section is replaced with 8-bit data, the difference is large in the length of the 1T image of "0" or the 1T image of "1". The ratio of 1: 1 in FIG. 7 is 1: 3 in FIGS. 8 and 9.

9, the length ratio of the 1T image of "0" or the 1T image of "1" was increased to 1: 6 according to the change of ISO which is the amplification gain of the image sensor. As the ISO increases, the length of the image of “1” increases. Asymmetry is getting worse. Instead, the 1T image of “0” and the 2T image of “0” show a difference of three times the length ratio in ISO 100 and a difference of five times the length ratio in ISO 3200. In other words, it is easier to distinguish the “0” value from the data “1” value. In FIG. 9, the image of “1” is the resultant image of 1T and 3T, respectively. The image should be three times the size, but with slightly smaller results. Comparing the 2T image of "0" and the 1T image of "1", the width of the 1T image of "1" is rather asymmetrical.

Display devices have different horizontal and vertical pixel numbers. As a result, the image of the stripe pattern on the device is inevitably different. When displayed on the display from an image sensor, the server is sampled and displayed, so the relative sizes are the same, but the absolute sizes are all different.

Therefore, the image of “1” and the image of “0” should be distinguished by the ratio of pulse width, not absolute size. In this embodiment, a start code is indicated by an image of "1", and a data code is represented by an image of "0". In addition, a 1T long “0” image is included in the start start code to be a reference for decoding the data code. Adding a 2T long "0" image and a 3T long "0" image to the start code serves as a reference code when decoding the data code, but has the disadvantage of increasing the total length of the data. Therefore, in this embodiment, only "T" image of 1T is added to the start code.

IoT has a variety of applications. As there are various applications, communication methods also need various methods. There is also a need to use a small LED area and use it in mobile mobile environments. In order to use a small LED area, there is a premise that a minimum size of an image formed on an image sensor of a camera must be secured. In addition, there should be no drop of data as much as data is transmitted through an asynchronous video signal. In the present invention, a suitable modulation method is studied. In order to conduct such research, basically, an analysis of data transmitting apparatus and receiving apparatus is required. The optical transmission device is to turn the LED on and off one-dimensionally in time. It's not very fast, so there's nothing wrong with it. However, there are many situations to consider the optical receiving device. This is because data must be received through a device that receives a 3D video signal. Therefore, it is necessary to check how the image sense, which is an image signal receiving device, operates to receive a signal, and transmit the signal so that there is no problem in the receiving operation. That is, a signal must be generated so that there is no problem in reception in the optical transmitter having a high degree of freedom. Therefore, the characteristics of the image sensor were first checked, a signal was generated in the optical transmitter to satisfy the characteristic, and whether the data of the optical transmitter was safely received by the optical receiver was checked.

The term '~ part' used in the present embodiment refers to software or a hardware component such as a field-programmable gate array (FPGA) or an ASIC, and '~ part' performs certain roles. However, '~' is not meant to be limited to software or hardware. '~ Portion' may be configured to be in an addressable storage medium or may be configured to play one or more processors. Thus, as an example, '~' means components such as software components, object-oriented software components, class components, and task components, and processes, functions, properties, procedures, and the like. Subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functionality provided within the components and the 'parts' may be combined into a smaller number of components and the 'parts' or further separated into additional components and the 'parts'. In addition, the components and '~' may be implemented to play one or more CPUs in the device or secure multimedia card.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims

A light source unit including at least one light source element; And

A driving unit for controlling the driving of the light source element to output an optical signal,

The driving unit,

A first frame including the first data code and a first start code inserted at a start point of the first data code, and a second frame inserted at a start point of the second data code and the second data code And generating a second frame including a start code, and outputting the first frame and the second frame to control driving of the light source element.
The method of claim 1,

And the first start code and the second start code comprise different codes.
The method of claim 2,

And a plurality of start codes and data codes are repeatedly inserted into a single frame of each of the first frame and the second frame.
The method of claim 2,

And a parity bit is added to the last bit of the first data code and the second data code.
The method of claim 1,

And the first data code and the second data code represent data according to a row interval pulse width.
The method of claim 2,

And a gap code (Gap Code) for classifying a frame is added between the first data code and the second data code.
An optical signal transmission device including a light source unit including at least one light source element and a driving unit controlling the driving of the light source element and outputting an optical signal;

An optical signal receiving device for receiving the optical signal,

The driving unit includes a first frame including the first data code and a first start code inserted at a start point of the first data code, and at a start point of the second data code and the second data code. And generating a second frame including a second start code to be inserted, and outputting the first frame and the second frame to control the driving of the light source element.
The method of claim 7, wherein

The optical signal receiving device,

An image sensor detecting the optical signal;

A photoelectric conversion unit converting the detected optical signal into an electrical signal; And

Optical signal communication device comprising a decoding unit for decoding the converted electrical signal.
The method of claim 8,

And the decoding unit performs synchronization using the first start code and the second start code.
The method of claim 9,

And the decoding unit decodes a data code in an arbitrary frame and does not perform decoding on the detected optical signal until the start code of a frame different from the corresponding frame is detected.