Information transfer system

Abstract

To provide an information transfer system that uses a light-emitting diode to transfer information, and that can be realized at a low cost by utilizing existing hardware.SOLUTION: An information transfer system comprises: a display device that displays one or a plurality of light-emitting diodes being in a predetermined condition or at a predetermined brightness by turning on the light-emitting diodes; an imaging device that generates moving image data by capturing the display device using an image pickup device; and an analyzing device that specifies predetermined information by analyzing the moving image data. More specifically, the imaging device is driven in a moving image capture mode to generate the moving image data, and the analyzing device extracts predetermined frequency information from the moving image data to specify predetermined information that is previously associated with this frequency information.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an information transmission system using light-emitting diodes. [Background technology]

[0002] Lighting devices and display devices using light-emitting diodes (LEDs) are now widely used. Although LEDs appear to emit light constantly when turned on, they actually blink at a rate too fast for the human eye to perceive. One of the reasons for this is that they use AC power, which also helps reduce power consumption.

[0003] In particular, in eastern Japan, they are often flashed at 100 Hz in response to a 50 Hz AC power supply, and in western Japan, they are often flashed at 120 Hz in response to a 60 Hz AC power supply. In this invention, this state in which the light-emitting diode is turned on and flashes, and is recognized as always emitting light, is referred to as the "illuminated" state.

[0004] When lighting up a light-emitting diode, a predetermined current is generally passed through the light-emitting diode using a square wave signal of 100 Hz or 120 Hz, but this square wave signal can be adjusted to function as an information transmission means. For example, a map information system has been proposed that transmits reference position information using traffic lights that use heating bulbs or light-emitting diodes (see, for example, Patent Document 1).

[0005] In this map information system, when turning on a traffic light's green light, the reference position information is converted into binary data of "0" and "1" and a square wave signal is modulated between "0" and "1" to turn on the light. The light from this traffic light is received by a light receiving means such as an optical sensor and converted into an electrical signal, which is then demodulated to identify the reference position information and enable the transmission of the reference position information. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 05-224596 Summary of the Invention [Problem to be solved by the invention]

[0007] The optical sensor, which is the light receiving means, is an imaging element known as a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor, and is usually operated with a drive signal having a higher clock frequency than the square wave signal used for the light emitting diode to be detected, thereby making it possible to distinguish between the lit and extinguished states of the light emitting diode. In other words, when using the light receiving means, a dedicated signal processing device is required, and this signal processing device requires high-clock signal processing, making it a relatively expensive device.

[0008] The inventors of the present invention were considering whether it would be possible to transmit information using imaging elements such as CCD image sensors and CMOS image sensors, which are installed in modern mobile phones, and their driving circuits, rather than using expensive signal processing devices, and this led to the creation of the present invention.

[0009] That is, an object of the present invention is to provide an information transmission system that transmits information using light-emitting diodes, and that can be realized inexpensively by utilizing existing hardware. [Means for solving the problem]

[0010] The information transmission system of the present invention is an information transmission system including a display device that lights up one or more light-emitting diodes to indicate a predetermined state or to set the display device to a predetermined brightness, a photographing device that generates video data by photographing the display device using an image sensor, and an analysis device that identifies predetermined information by analyzing the video data. In particular, the information transmission system of the present invention is characterized in that the photographing device is driven in a video photographing mode to generate video data, and the analysis device extracts predetermined frequency information from the video data and identifies predetermined information that has been previously associated with the frequency information.

[0011] The information transmission system of the present invention also has the following features. (1) The frequency information is a frequency based on the drive frequency that lights up the light-emitting diode, a predetermined frequency superimposed on the drive frequency, or a modulation frequency obtained by modulating the drive frequency. (2) The frequency information is a frequency that is different from the frame rate of the imaging device or a frequency based on an integer multiple of the frame rate. (3) The display device is a taillight of an automobile or motorcycle. (4) The display device is a traffic light or information display board installed on the road. (5) The display device is a street light or indoor lighting. [Effects of the Invention]

[0012] According to the present invention, the imaging element is driven in the video shooting mode of the photographing device to generate video data, and the analysis device extracts predetermined frequency information from the video data and identifies predetermined information that has been previously associated with this frequency information.This allows the system to be constructed using existing hardware that is generally available, making it possible to introduce the system at low cost. [Brief explanation of the drawings]

[0013] [Figure 1]FIG. 10 is a timing chart illustrating detection of a state in which a light-emitting diode is not emitting light. [Figure 2] FIG. 1 is an explanatory diagram of an embodiment of the present invention. [Figure 3] FIG. 1 is an explanatory diagram of an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] The information transmission system of the present invention is an information transmission system that includes a display device that lights up one or more light-emitting diodes to indicate a predetermined state or to set the brightness to a predetermined level, a photographing device that generates video data by photographing the display device using an image sensor, and an analysis device that identifies predetermined information by analyzing the video data.

[0015] Display devices include one or more light-emitting diodes, and are nowadays used as traffic light signals, various automobile lamps, various display devices, etc. Street lights and indoor lighting are also considered to be display devices in the present invention.

[0016] The display device includes a drive circuit that lights up each light-emitting diode using power supplied from an appropriate power source. As will be described later, in the present invention, the display state of the display device, specifically, the drive signal that drives the light-emitting diode, is adjusted to transmit predetermined information as the light-emitting diode lights up. Therefore, the display device may be provided with an adjustment circuit for adjusting the drive signal.

[0017] The imaging device is equipped with a so-called CCD image sensor or CMOS image sensor as an imaging element, and in this invention, a device equipped with such an imaging element and capable of generating video data in a video shooting mode is referred to as an imaging device. Specifically, this includes a smartphone with a camera function, an in-vehicle camera for a drive recorder, a camera for monitoring, etc.

[0018] When operating in video shooting mode, the imaging device generally operates at a frame rate of 30 fps or 60 fps. In the present invention, unless otherwise specified, the frame rate will be described as 30 fps. However, 15 fps or 24 fps are also acceptable for the present invention.

[0019] The analysis device is capable of analyzing the video data generated by the imaging device, and specifically, is a computing device capable of executing an appropriate analysis program. More specifically, it is a smartphone with a camera function, an in-vehicle camera for a drive recorder, a monitoring camera, or the like, which has a built-in analysis program, and functions as an analysis device by executing the analysis program.

[0020] The analysis program identifies an area in each frame constituting the video data where light-emitting diodes are captured, and detects a state in which the light-emitting diodes in the identified area are not emitting light, i.e., are off. More specifically, it detects a decrease in brightness due to the light-emitting diodes being off. Note that, for example, if the imaging device and analysis device are a drive recorder for an automobile or the like, an appropriate image analysis program may be used to identify traffic lights or taillights of a preceding vehicle that are captured in each frame constituting the video data, and identify the area in which the light-emitting diode to be detected is captured.

[0021] Here, detection of a state in which the light-emitting diode is not emitting light will be explained using the timing chart in Fig. 1. For the sake of convenience, the image capturing device captures images at a frame rate of 30 fps to generate video data, so the shutter control signal in the image capturing device is a 30 Hz square wave, and the length of time that this shutter control signal is in the on state corresponds to the shutter speed.

[0022] For ease of explanation, it is assumed that the drive signal for the light-emitting diodes is a square wave with a frequency of 30 Hz, 35 Hz, 40 Hz, 45 Hz, 50 Hz, 55 Hz, or 60 Hz and a duty ratio of 50% to light up the light-emitting diodes. Note that the duty ratio does not necessarily have to be 50%, and the signal does not necessarily have to be a square wave.

[0023] As shown in Figure 1, if the imaging device and the light-emitting diode are initially synchronized, when the light-emitting diode is driven at 30 Hz and 60 Hz, the light-emitting diode will always be photographed in an on-state, emitting light.

[0024] On the other hand, when the light-emitting diodes are not driven at 30 Hz or 60 Hz, the light-emitting diodes are photographed at a predetermined timing when they are in the off state. When the light-emitting diodes are in the off state, they are not emitting light and are turned off.

[0025] More specifically, when a light-emitting diode is driven at 35 Hz, the off state of the light-emitting diode is to appear at 5 Hz intervals. When a light-emitting diode is driven at 40 Hz, the off state of the light-emitting diode is to appear at 10 Hz intervals. When a light-emitting diode is driven at 45 Hz, the off state of the light-emitting diode is to appear at 15 Hz intervals. When a light-emitting diode is driven at 50 Hz, the off state of the light-emitting diode is to appear at 10 Hz intervals. When a light-emitting diode is driven at 55 Hz, the off state of the light-emitting diode is to appear at 5 Hz intervals.

[0026] In this way, if the information about the frequency of the drive signal input to the light-emitting diode is known in advance and the drive signal has a frequency other than that based on the frame rate of the imaging device or an integer multiple thereof, the frequency of the drive signal input to the light-emitting diode can be determined from the interval at which the light-emitting diode appears to be off in the image data generated by the imaging device.

[0027] Specifically, the analysis device calculates the average brightness in the area of ​​the video data where the light-emitting diode is reflected in each frame, generates brightness data based on the change in this average brightness, and performs a Fourier transform on this brightness data to obtain frequency data that shows a peak at a specific frequency.In other words, it is possible to extract frequency information of the drive signal that drives the light-emitting diode based on the frequency of the peak.

[0028] Furthermore, if the information on the frequency of the drive signal input to the light-emitting diode is known in advance, it is also possible to identify the frequency information of the drive signal that drives the light-emitting diode from the interval at which the light-emitting diode appears to be off in the image data generated by the imaging device.

[0029] The frequency information to be extracted may be the drive frequency itself that lights up the light-emitting diode, or if a signal of a predetermined frequency is superimposed on the drive frequency to form a composite signal, the frequency of the superimposed signal may be used. Alternatively, if a rectangular wave of the drive frequency is modulated to form a modulated signal, the frequency information may be used based on the modulation frequency.

[0030] The analysis device stores predetermined information in association with the extracted frequency information in advance, thereby enabling the device to identify the predetermined information. Specifically, as will be described later, by detecting different frequency information in the taillights of an automobile made up of light-emitting diodes depending on whether the automobile is decelerating or stopped, it becomes possible to identify whether the lit taillights of a preceding vehicle indicate a decelerating state or a stopped state. [Example]

[0031] <When the display device is a tail lamp of an automobile or motorcycle> Modern cars use light-emitting diodes in their headlights and taillights, and increasingly they are equipped with dashcams to combat nuisance driving and provide evidence in the event of a traffic accident.

[0032] Therefore, by utilizing the video recording function of the drive recorder, it is possible to receive information from the tail lamps of the preceding vehicle as follows. Here, as shown in Fig. 2, preceding vehicle 10 is capable of generating, as drive signals for driving the light-emitting diodes (not shown) of tail lamps 11, a first drive signal that is input to the light-emitting diodes when the brake pedal (not shown) is depressed to decelerate the vehicle, and a second drive signal that is input to the light-emitting diodes when the brake pedal is depressed even when the vehicle is stopped. The first drive signal and the second drive signal are signals with different frequencies that capture a state in which the light-emitting diodes are off when recording in video recording mode with the drive recorder camera.

[0033] In this embodiment, the first drive signal is generated by signal generation circuit 12, and the first drive signal generated by signal generation circuit 12 is input to adjustment circuit 13, which then inputs the first drive signal to light-emitting diode drive circuit 14 depending on the operation state of the brake pedal. An output signal from vehicle speedometer 15 is input to adjustment circuit 13, and when the vehicle speed becomes "0," adjustment circuit 13 modulates the first drive signal to generate a second drive signal, and inputs this second drive signal to light-emitting diode drive circuit 14. Adjustment circuit 13 may generate the second drive signal by superimposing an appropriate signal on the first drive signal, or signal generation circuit 12 may generate the first drive signal and the second drive signal in advance, and adjustment circuit 13 may be performed to output either the first drive signal or the second drive signal.

[0034] A following vehicle 20 traveling behind a leading vehicle 10 is equipped with a drive recorder 21, and the camera of this drive recorder 21 captures images of the leading vehicle 10 in video recording mode to generate video data. In this embodiment, the drive recorder 21 is both a recording device and an analysis device, and identifies the tail lamps 11 of the leading vehicle 10 from the generated video data and detects the intervals at which the light-emitting diodes of the tail lamps 11 appear to be off.

[0035] The drive recorder 21 detects that the light-emitting diode of the tail lamp 11 of the preceding vehicle 10 is emitting light in response to the second drive signal, and if the vehicle speed of the following vehicle 20 is faster than a predetermined vehicle speed, it will output an appropriate warning sound or a warning voice saying "There is a parked vehicle" to alert the driver of the following vehicle 20.

[0036] In particular, when driving at night, it can be difficult to distinguish between a "decelerating state" and a "stopped state" simply by turning on the taillights, which stand out in the darkness, and this can lead to a delay in braking. However, by being able to distinguish between a "stopped state" as described above, it is possible to easily eliminate the driver's misperception. Therefore, it is possible to more easily prevent rear-end collisions with stopped vehicles due to a delay in braking. [Example]

[0037] <When the display device is a traffic light installed on a road> Traffic light indicators are made up of multiple light-emitting diodes. For example, if there is traffic congestion due to an accident on the road where the traffic light is installed, the indicator light can be displayed differently from when there is no accident, thereby notifying drivers in advance of the traffic congestion due to the accident.

[0038] As shown in Figure 3, the traffic light 30 of this embodiment is equipped with an antenna 31 to enable signal input via wireless communication, and based on the control signal input from the antenna 31, it is possible to switch the drive signal input to a drive circuit (not shown) that drives multiple light-emitting diodes (not shown) that make up the signal lights of the traffic light 30.

[0039] That is, the traffic light 30 of this embodiment is provided with a signal output unit (not shown) that stores a plurality of types of drive signals in advance, and switches the drive signal to be input to the drive circuit (not shown) based on the control signal input from the antenna 31. The intervals at which the light-emitting diode is turned off are made different for each drive signal.

[0040] Normally, the first drive signal is input to the drive circuit to put it into a normal operating state, and a control signal is input from the antenna 31 to input a second drive signal to the drive circuit, so that the vehicle 20' equipped with the drive recorder 21 can detect the second drive signal by using the video recording function of the drive recorder. For example, by setting in advance that the second drive signal is information indicating "traffic jam occurring 3 km ahead," the driver of the vehicle 20' can decide whether to stop and check the situation or take a detour.

[0041] Furthermore, by inputting a third drive signal, which is different from the first drive signal and the second drive signal, into the drive circuit, the third drive signal can be detected by the vehicle 20' equipped with the drive recorder 21, and by presetting the third drive signal to be information indicating, for example, that "traffic jam will occur 10 km ahead," the driver of the vehicle 20' can be provided with a situation in which more options can be considered.

[0042] Furthermore, when a traffic light is configured with a relatively large number of light-emitting diodes, such as the signal lights of traffic light 30, a set may be configured with multiple light-emitting diodes, and each set may be driven with a different drive signal, making it possible to transmit multiple pieces of information at once, and making it possible to transmit not only traffic congestion information but also other appropriate information. [Example]

[0043] <When the display device is an information display board installed on the road> Instead of the traffic light 30 described above, information can be transmitted in the same manner as the traffic light 30 described above using an information display board made up of a number of light emitting diodes.

[0044] In particular, since information display boards are relatively large, as described above, a set can be made up of multiple light-emitting diodes, and each set can be driven with a different drive signal, making it possible to transmit multiple pieces of information at once. [Example]

[0045] <When the display device is a street light> Recently, light emitting diodes have come to be used in lighting devices such as street lights.

[0046] These street lights can also be driven by multiple types of drive signals, just like the traffic light 30 described above, and can receive predetermined information using the video recording mode of a smartphone camera. Alternatively, in the case of smart glasses, which are expected to become more popular in the future, it is possible to receive predetermined information while wearing the smart glasses and moving around.

[0047] In addition, some tunnels on expressways are relatively long, making it difficult to properly correct GPS location information. However, the lighting inside the tunnel can be used to transmit information such as the distance to the tunnel exit, allowing for location information to be corrected. [Example]

[0048] <When the display device is an indoor light> This type of interior lighting can also be driven by multiple types of drive signals, similar to the traffic light 30 described above, and can also receive predetermined information using an appropriate camera's video recording mode.

[0049] For example, the route of an automated guided vehicle used in a factory can be set using indoor lighting. That is, by driving the indoor lighting with a drive signal that transmits address information, the automated guided vehicle can move independently while following the address information transmitted from the indoor lighting. In particular, the specifications of the indoor lighting can be set according to the size of the address information, and any setting is possible. [Explanation of symbols]

[0050] 10 Leading vehicle 11 Tail lamp 12 Signal generation circuit 13 Adjustment circuit 14 Drive circuit 15 Speedometer 20 Following vehicles 21 Drive Recorder

Claims

1. a display device that lights up one or more light-emitting diodes to indicate a predetermined state or to a predetermined brightness; an imaging device that captures an image of the display device using an imaging element to generate video data; an analysis device that identifies predetermined information by analyzing the video data; An information transmission system comprising: the imaging device is driven in a video imaging mode to generate the video data; The analysis device extracts predetermined frequency information from the video data, and identifies the predetermined information that has been previously associated with this frequency information. Information transmission system.

2. 2. The information transmission system according to claim 1, wherein the frequency information is a frequency based on a drive frequency that lights up the light-emitting diode, a predetermined frequency superimposed on the drive frequency, or a modulation frequency obtained by modulating the drive frequency.

3. 3. The information transmission system according to claim 1, wherein the frequency information is a frequency different from a frame rate of the moving image shooting mode or a frequency based on an integral multiple of the frame rate.

4. 3. The information transmission system according to claim 1, wherein the display device is a tail lamp of an automobile or a motorcycle.

5. 3. An information transmission system according to claim 1, wherein the display device is a traffic light or an information display board installed on a road.

6. 3. The information transmission system according to claim 1, wherein the display device is a street lamp or an indoor light.

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