Signal system and signal lamp

Abstract

To provide a signal system of visible light communication which can prevent flashing or flickering from being visible or conspicuous even without high-speed switching in communication using visible light.SOLUTION: A signal system 100 comprises: a polarization conversion unit 22 that converts the polarization state of light source light GL in accordance with a signal content to make emission light EL on a signal device side; and a signal reading unit 12s that reads the signal content on the basis of received light corresponding to the polarization state of the emission light EL. This signal system 100 enables signal transmission using polarization state switching. In this case, even if a signal switching operation for communication using, for example, visible light, is slow, flashing or flickering can be prevented from being visible.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a signal system and a signal lamp that can be applied to, for example, railway facilities and the like. [Background technology]

[0002] For example, known visible light communication technologies are incorporated into projectors and lighting control systems (see Patent Documents 1 and 2). The visible light communication in Patent Documents 1 and 2 is premised on high-speed switching so that blinking or flickering in the visible light wavelength band is not visible. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-179905 A [Patent Document 2] JP 2011-249134 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, when it is desired to use visible light communication in a signal system such as railway signals, it is conceivable that the signal lamps will be visible to people (drivers, etc.), and therefore it is considered necessary to have a method for switching at high speed so that blinking or flickering is not visible, as in the cases of Patent Documents 1 and 2 mentioned above.

[0005] However, for example, in cases where cameras or the like are installed on the top of trains for monitoring purposes in order to achieve automated train operation or driving assistance, and visible light communication is also used, it is considered that it is not necessarily easy to directly apply visible light communication, which switches at high speed as described above.

[0006] The present invention has been made in consideration of the above-mentioned points, and aims to provide a visible light communication signal system that can make blinking or flickering less visible or noticeable in communications using visible light without the need for high-speed switching. [Means for solving the problem]

[0007] A traffic light system to achieve the above-mentioned objective includes a polarization conversion unit on the traffic light side that converts the polarization state of the light source light in accordance with the signal content and outputs the converted light, and a signal reading unit on board the vehicle that reads the signal content based on received light in accordance with the polarization state of the emitted light.

[0008] In the above-described signal system, signal transmission is possible by switching the polarization state. In this case, even if the signal switching operation for communication using visible light is slow, blinking or flickering can be prevented from being visible.

[0009] In a specific aspect of the present invention, the polarization conversion unit switches the polarization direction of linearly polarized light for the emitted light and emits the light, and includes an up-vehicle polarizing plate that transmits the emitted light that is linearly polarized in one direction and absorbs the emitted light that is linearly polarized in the other direction at the up-vehicle side. In this case, the content of the signal can be read at the up-vehicle side by the transmission / absorption of the emitted light at the up-vehicle polarizing plate in response to switching of the polarization direction of the linearly polarized light at the polarization conversion unit.

[0010] In another aspect of the present invention, the polarization conversion unit emits the emitted light with a circularly polarized state, and includes an on-board λ / 4 waveplate that converts the circularly polarized emitted light into linearly polarized light on the on-board side. In this case, by converting the polarization state of the emitted light with the on-board λ / 4 waveplate, the signal content can be read on the on-board side.

[0011] In yet another aspect of the present invention, the signal reader reads the signal content from brightness information in receiving the emitted light. In this case, by reading the on / off signal from the brightness information, the signal content can be grasped from the vehicle interior.

[0012] In yet another aspect of the present invention, the polarization conversion section has a liquid crystal panel that converts the polarization state of the emitted light. In this case, the liquid crystal panel can easily and reliably switch the polarization state at a desired speed.

[0013] In yet another aspect of the present invention, an imaging unit is provided on the upper side of the vehicle that captures continuous images of the external environment and receives the emitted light. In this case, the imaging unit can read the signal content based on switching the polarization state of the emitted light while acquiring information about the external environment.

[0014] In yet another aspect of the present invention, the frequency of light conversion in the polarization conversion unit is lower than the frame rate of the imaging unit. In this case, the signal content based on the switching of the polarization state of the emitted light can be accurately read using information acquired by the imaging unit.

[0015] In yet another aspect of the present invention, a light source unit that emits light in the visible light wavelength band as the emitted light is provided on the traffic light side. In this case, it is possible to transmit and receive signals by switching the polarization state of the light from the light source unit.

[0016] According to yet another aspect of the present invention, the signal reading unit reads the signal content as an automatic driving signal. In this case, transmission and reception of signals related to the automatic driving signal can be performed accurately.

[0017] A signal lamp for achieving the above object includes a light source unit that emits a source light, and a polarization conversion unit that converts the polarization state of the source light from the light source unit in accordance with the signal content to produce emitted light.

[0018] The above-mentioned signal lamp makes it possible to transmit signals by switching the polarization state. In this case, it is possible to form emitted light that does not flash or flicker visually, even if the signal switching operation for communication using visible light is slow. [Brief description of the drawings]

[0019] [Figure 1]FIG. 1 is a schematic diagram for explaining the state of a railway in which a signaling system according to a first embodiment and a signal lamp constituting the signaling system are incorporated; [Diagram 2] 1 is a conceptual block diagram for explaining an example of the configuration of a signal system and a signal lamp that constitutes the signal system. [Diagram 3] FIG. 1 is a conceptual diagram showing an example of the operation of a signal system. [Figure 4] (A) is a time chart showing one example of the transmission and reception relationship between the transmitting side and receiving side of a signal, and (B) is a time chart showing another example of the transmission and reception relationship between the transmitting side and receiving side of a signal. [Diagram 5] FIG. 1 is a conceptual diagram showing an overview of a signal system. [Figure 6] FIG. 11 is a conceptual block diagram for explaining a configuration example of a signal system according to a second embodiment and a signal lamp constituting the signal system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] [First embodiment] Hereinafter, an example of the signal system of this embodiment and the signal lamps constituting the same will be described with reference to Fig. 1 and the like. Fig. 1 is a schematic diagram for explaining the signal system 100 of this embodiment and the signal lamps 20 constituting the same, and Fig. 1 illustrates the signal system 100 when applied to signal communication processing between the onboard side and the ground side (signal side) performed during automatic operation of a train TR. The signal system 100 functions as a railway signal by transmitting a plurality of types of signal information. In particular, in this embodiment, in the above-mentioned configuration, when the signal lamps 20 are turned on, in addition to displaying a signal by controlling the lighting of light in the visible light wavelength band, the signal content is also transmitted by converting the polarization state of the light according to the signal content.

[0021] In addition, various aspects are assumed for the automatic operation of the train TR mentioned above, and it is considered to include a wide range of aspects, from completely unmanned automatic operation without a driver, etc., to a system in which a driver performs driving operations and partially assists with the automatic operation.

[0022] An outline of a signaling system 100 according to this embodiment and one configuration example of the signaling lamp 20 constituting the signaling system 100 will be described below. As shown in Fig. 1, the signaling system 100 comprises a receiving device 10 that receives various information including the contents of signal indications, a signaling lamp 20 that is a transmitting device that transmits various information such as the contents of signal indications, and a signal generating device 30 that generates the contents of signal indications to be transmitted from the signaling lamp 20. Of these, the receiving device 10 is mounted on the train TR as an on-board device that receives signals from the ground side. Meanwhile, the signaling lamp 20 and the signal generating device 30 are installed around the track RL as devices for transmitting signals from the signal side, i.e., the ground side.

[0023] First, the receiving device 10 is composed of a camera (image sensor) and functions as an imaging unit. More specifically, the receiving device 10 is mounted on the train TR, and captures continuous images of the external environment of the train TR as an imaging unit on the train TR side, i.e., on the vehicle. The receiving device 10 is capable of acquiring, analyzing, or extracting various information for automatic operation of the train TR or for assisting the automatic operation from various acquired image data. For this reason, the receiving device 10 is mounted facing forward so as to capture an image of the traveling direction of the train TR. In other words, the receiving device 10 is capable of acquiring various images of the external environment in addition to the signal lamp 20 present ahead in the traveling direction of the train TR. In addition to the above, particularly in this embodiment, the receiving device 10 is capable of reading the signal contents based on the light reception according to the polarization state for the light as signal information transmitted from the signal lamp 20. This point will be described in detail later.

[0024] On the other hand, the signal lamps 20 and the signal generating device 30 are devices installed on the ground side that transmit information regarding the progress of the train TR, and display signals to the train TR, or more precisely, to the receiving device 10 mounted on the train TR.

[0025] Hereinafter, the configuration of the signal lamp 20 and the signal generating device 30 will be described first. The signal lamp 20 has a red signal lamp 20r that emits light in a red wavelength band, a yellow signal lamp 20y that emits light in a yellow wavelength band, and a blue signal lamp 20g that emits light in a blue wavelength band as indicator lamps using visible light to function as a railway signal or a part thereof, and further has a lighting control unit LC that controls the lighting and extinguishing of these, and performs light emission operations. That is, in the signal lamp 20, the red signal lamp 20r, etc. are turned on and off in accordance with a drive operation command from the lighting control unit LC, thereby transmitting information about the progress of the train TR to people, sensors, etc. that can detect visible light as a railway signal.

[0026] In this embodiment, the polarization state of the light of each color wavelength band is converted in the signal lamp 20 according to the signal content, and the converted light is emitted as the emitted light EL. On the other hand, on the vehicle side, that is, on the receiving device 10 side, as described above, the signal content is read based on the received light according to the polarization state of the emitted light EL. In other words, the signal system 100 of this embodiment is capable of transmitting and receiving signals by switching the polarization state. In this embodiment, the emitted light EL is switched between a first polarized light LLp that is emitted in a state of linear polarization polarized in one direction and a second polarized light LLs that is emitted in a state of linear polarization polarized in the other direction. Typically, the first polarized light LLp and the second polarized light LLs are assumed to be polarized in orthogonal directions, and the first and second polarized light LLp, LLs will be treated as such in the following. The receiving device 10 detects the difference between the first polarized light LLp and the second polarized light LLs, thereby making it possible to read the signal content, that is, to restore the transmitted signal.

[0027] The signal generating device 30 is a device for generating signals to be transmitted from the signal lamp 20, and outputs various information, such as information about the signal lamps to be turned on in the above-mentioned signal lamp 20, to the lighting control unit LC of the signal lamp 20.

[0028] Hereinafter, with reference to FIG. 2 etc., a detailed description will be given of an example of the configuration of the signal system 100 of this embodiment and the signal lamp unit 20 constituting the signal system 100.

[0029] First, the signal lamp 20 will be described among the components constituting the signal system 100. As described above, the signal lamp 20 includes the color signal lamps 20r, 20y, and 20g and a lighting control unit LC, and displays a signal according to various information generated by the signal generating device 30. In particular, the signal lamp 20 converts the polarization state of the emitted light EL. In order to explain this in detail, the configuration of the signal lamp 20 is redrawn in the illustrated example. Specifically, the signal lamp 20 is composed of a light source unit 21 that emits light source light GL, and a polarization conversion unit 22 that converts the polarization state of the light source light GL from the light source unit 21 according to the signal content and outputs the converted light EL. Here, the configuration of the blue signal lamp 20g among the color signal lamps 20r, 20y, and 20g is shown when it is controlled by the lighting control unit LC. However, the other color signal lamps 20r and 20y can be configured in the same way, so illustrations and descriptions of the color signal lamps 20r and 20y are omitted.

[0030] First, the lighting control unit LC is configured with a power supply board PB that controls the supply of power, a light source control unit 21s that performs drive control related to the emission of the light source light GL, and a polarization control unit 22c that performs drive control related to switching of the polarization state, as shown in the figure. Of these, the light source control unit 21s constitutes the light source unit 21 that emits the light source light GL, and the polarization control unit 22c constitutes the polarization conversion unit 22 that converts the polarization state. The light source control unit 21s and the polarization control unit 22c operate according to commands from the signal generating device 30.

[0031] In the signal lamp device 20, the light source unit 21 is composed of the light source control unit 21s described above and a light emitting unit 21e composed of a plurality of LED elements. That is, in the light source unit 21, the light source unit 21 emits light source light GL of a specific color (in this example, a blue signal) by the light emitting unit 21e performing operations such as turning on and off (extinguishing) or blinking by repeating this in accordance with drive control by the light source control unit 21s.

[0032] Of the traffic light fixture 20, the polarization conversion unit 22 is composed of, in addition to the polarization control unit 22c described above, a traffic light side polarizing plate (polarizer) 22a arranged immediately rear of the light source unit 21, and a liquid crystal panel 22p arranged immediately rear of the traffic light side polarizing plate 22a.

[0033] The traffic light side polarizing plate 22a converts the polarization state of the source light GL from the light source unit 21 into linearly polarized light in a specific direction.

[0034] The liquid crystal panel 22p operates according to a command from the polarization control unit 22c. That is, by turning on and off the liquid crystal panel 22p, the component of the light source light GL that should become the emitted light EL after passing through the traffic light side polarizing plate 22a is switched between the case where the component is emitted while maintaining the linear polarization state as it is, and the case where the component is emitted while changing the polarization state by 90 degrees. The liquid crystal for the liquid crystal panel 22p can be of various types, such as the TN type, the VA type, and the IPS type, and the attitude of the liquid crystal is changed according to an on / off signal according to the timing from the polarization control unit 22c, and the polarization direction of the linearly polarized light is changed or not. As described above, the liquid crystal panel 22p changes the polarization state of the component light that should become the emitted light EL from the light source light GL.

[0035] Here, the emitted light EL, which has been linearly polarized after passing through the traffic light side polarizing plate 22a and is maintained as it is at the liquid crystal panel 22p, is referred to as the first polarization LLp, and the emitted light EL, which has been linearly polarized after being converted by 90 degrees at the liquid crystal panel 22p, is referred to as the second polarization LLs.

[0036] With the above configuration, the polarization conversion unit 22 switches the polarization direction of the emitted light EL according to the signal content to be transmitted determined by the polarization control unit 22c, and emits the light. From the above, it can be said that, when viewed from the entire signal lamp device 20, the light source unit 21 emitting the source light GL emits light in the visible light wavelength band as the light to be the emitted light EL.

[0037] Next, the receiving device 10 will be described among the components constituting the signal system 100. The receiving device 10 receives the emitted light EL emitted from the traffic light side, i.e., from the signal lamp 20. At this time, the receiving device 10 reads the signal contents based on the received light according to the polarization state of the emitted light EL, so that the receiving device 10 can receive a signal according to the signal transmission using the switching of the polarization state on the traffic light side. In order to enable the above-mentioned aspect, the receiving device 10 includes a camera 11 for functioning as an imaging unit as described above, and an image processing unit 12 for processing various information such as image data acquired by the camera 11. In addition to these, in the receiving device 10 in this embodiment, an upper vehicle polarizing plate (analyzer) 13 is provided in front of the camera 11. The image processing unit 12 also includes a signal reading unit 12s for reading the transmitted signal contents using the conversion of the polarization state.

[0038] The vehicle upper polarizing plate 13 is disposed on the vehicle upper side in an orientation such that it transmits the exit light EL that is linearly polarized in one direction and absorbs the exit light EL that is linearly polarized in the other direction. A more detailed example of this will be described later with reference to FIG. 3.

[0039] The camera 11 of the receiving device 10 has an image sensor 11s composed of, for example, a CCD or a CMOS. The brightness of the light received by the image sensor 11s is converted into an electric signal and output as image data to the image processing unit 12. The camera 11 is capable of capturing continuous images at a predetermined frame rate. In other words, the camera 11 captures continuous images of the external environment of the train TR.

[0040] The image processing unit 12 is composed of, for example, various circuit elements, and performs analysis processing on image data from the camera 11. More specifically, the image processing unit 12 performs various image analyses to determine whether or not the image contains any items that may affect railway operations, such as whether or not a person has entered the track captured by the camera 11, the traffic conditions around a railroad crossing, or the occurrence of an emergency signal. Furthermore, the image processing unit 12 may be configured to perform a judgment processing based on the analysis results.

[0041] In the above situation, in this embodiment, the receiving device 10 further enables information transmission from the traffic light side (ground side) to the on-board side based on switching of the polarization state by allowing or not allowing passage of linearly polarized light depending on a specific direction by the on-board polarizing plate 13, and reading a signal based on brightness information about the linearly polarized light by the signal reading unit 12s provided in the image processing unit 12.

[0042] Hereinafter, the above-mentioned information transmission will be described in detail with reference to FIG. 3 and the like. First, as shown in FIG. 3 and as described above, on the traffic light side (ground side), only the linearly polarized component of the light source light GL emitted from the light source unit 21 is transmitted through the traffic light side polarizing plate 22a in a specific direction. In the illustrated example, the polarization direction of the linearly polarized light immediately after passing through the traffic light side polarizing plate 22a is set to a 0 degree direction. The linearly polarized component that has passed through the traffic light side polarizing plate 22a is incident on the liquid crystal panel 22p. As described above, the liquid crystal panel 22p maintains the polarization direction at 0 degrees to set the light in the first polarization LLp state, or changes the polarization direction by 90 degrees to set the light in the second polarization LLs state, at each predetermined timing in accordance with an instruction from the polarization control unit 22c. The emitted light EL that has passed through the liquid crystal panel 22p is emitted from the traffic light unit 20 in either the first polarization LLp or the second polarization LLs state at each timing.

[0043] Meanwhile, the receiving device 10 receives the emitted light EL from the signal lamp 20 according to its polarization state. In the illustrated example, the vehicle-upper polarizing plate 13 provided in the receiving device 10 transmits the emitted light EL, i.e., directs it toward the camera 11, when the emitted light EL is the first polarization LLp. Meanwhile, the vehicle-upper polarizing plate 13 absorbs the emitted light EL, i.e., blocks it, and does not direct it toward the camera 11, when the emitted light EL is the second polarization LLs. Therefore, on the vehicle-upper side, that is, in the image sensor 11s, only the first polarization LLp is detected, and the second polarization LLs is not detected, and accordingly, the signal reading unit 12s reads the signal content from the brightness information in receiving the emitted light EL. In other words, while the first polarized light LLp is being detected by the image sensor 11s, it is treated as having acquired bright information, and while the second polarized light LLs is reaching the receiving device 10, it is blocked by the vehicle-mounted polarizing plate 13 and is treated as dark information.

[0044] In this case, for example, the emission state of the first polarization LLp is set to "1" (on signal), and the emission state of the second polarization LLs is set to "0" (off signal), and these are transmitted in sequence at a predetermined timing, thereby enabling the transmission of a signal that combines "1" and "0". In other words, the arrangement of "1" and "0" is determined in advance so as to correspond one-to-one with the signal contents. In addition, various kinds of signal contents are assumed as the object to be read, and in addition to the case where the information corresponds to the color of the lighted signal (in this example, information that the signal display is "green"), it is also possible to include various kinds of information related to train operation, such as information about the platform where the train TR is currently stopped, in the signal contents.

[0045] An example of how the present embodiment handles signal transmission based on the above-mentioned brightness information will be described below with reference to Fig. 4. In both Fig. 4(A) and Fig. 4(B), the horizontal axis represents time.

[0046] First, in FIG. 4(A), chart α shows the state of the switching timing of the polarization state of the emitted light EL emitted from the traffic light side, which is the signal transmitting side. That is, the first polarization LLp (1: on signal) and the second polarization LLs (0: off signal) can be combined at a predetermined timing. In the illustrated example, the length of the transmission time of one signal is length T. That is, length T indicates the time length for sending one on signal or off signal, and corresponds to the conversion frequency of light (polarization state of light) in the polarization conversion unit 22. Chart α shows a case where the signal content is a series of "1, 1, 0, 1, 0...". In this case, on the receiving side of the signal, i.e., the vehicle's upper side, as shown in chart β, the vehicle's upper polarizing plate 13 transmits the first polarization LLp (1: on signal), while blocking (absorbing) the second polarization LLs (0: off signal). For this reason, as shown in the figure, the image sensor 11s detects light reception during the period corresponding to the first polarization LLp (1: on signal), and the signal reading unit 12s recognizes this as bright information. On the other hand, during the period corresponding to the second polarization LLs (0: off signal), no light reception is detected, and the signal reading unit 12s recognizes this as dark information. In this manner, the signal reading unit 12s reads the signal contents from the traffic signal side from the brightness information in receiving the emitted light PL. In this example, the signal reading unit 12s reads information related to the automatic operation signal of the train TR as the signal contents.

[0047] Here, in the illustrated example, the frequency of light conversion in the polarization conversion unit 22 is smaller than the frame rate in the camera 11 of the receiving device 10, which is an imaging unit. More specifically, in the illustrated example, the length of time corresponding to one frame is set as length t for the frame rate, and this length t is smaller than the length T indicating the unit length (conversion frequency of the emitted light PL) for the transmission time on the signal side. In other words, the frame rate in the camera 11 is larger than the frequency of light conversion in the polarization conversion unit 22. Note that the illustrated example shows a case in which the frame rate of the camera 11 is three times the frequency of light conversion, that is, T:t=3:1. In the above case, FIG. 4(A) shows a case in which the timing of switching the polarization state on the traffic light side and the timing of the division between frames on the vehicle-mounted camera 11 are aligned. In this case, since T:t=3:1, when three consecutive frames are "bright" on the image sensor 11s side, it detects an ON signal ("1") corresponding to one first polarization LLp, and conversely, when three consecutive frames are "dark" on the image sensor 11s side, it detects one OFF signal ("0"). Based on the above detection, the signal content from the traffic light is restored on the vehicle side.

[0048] In contrast, FIG. 4B shows a case where the timing of switching the polarization state on the traffic light side and the timing of the frame division on the vehicle-upper camera 11 are not aligned. Note that, here too, it is assumed that T:t=3:1. In this case, as shown in the chart γ, light conversion (switching of the polarization state of light) may occur on the traffic light side during one frame of image data acquired by the image sensor 11s. That is, during one frame, the transmission of the emitted light EL (first polarization LLp) by the vehicle-upper polarizing plate 13 and the absorption (blocking) of the emitted light EL (second polarization LLs) are switched, and the brightness information on the image sensor 11s becomes slightly dark (the degree of brightness is displayed as "medium" in the figure). Note that, in this case, for example, as shown by the circle in the figure, the detection of an on signal ("1") or an off signal ("0") can be determined by referring to the result of the brightness information after the brightness information becomes "medium". Specifically, in the above embodiment, T:t=3:1, so for example, when switching from "dark" to "light," "medium" will be followed by at least two more instances of "light," and when switching from "light" to "dark," the opposite phenomenon will occur.

[0049] The above embodiment is an example, and the switching frequency of the frame rate on the vehicle side and the polarization state on the traffic light side is not limited to 3:1, and can be in various embodiments. However, assuming that a general camera 11 for continuous imaging is used, the frame rate may be, for example, about 30 fps, and if it is 30 fps (i.e., one frame image is 1 / 30 seconds), and T:t=3:1 as in the above embodiment, the polarization switching will be about 1 / 10 seconds. This is very slow compared to visible light communication, which is assumed to require high-speed switching on the order of kilohertz from the viewpoint of preventing blinking and flickering, for example. Conversely, if visible light communication is performed by blinking visible light at a speed of about 1 / 10 seconds, the blinking and flickering will be visible to humans. In contrast, in this embodiment, the switching of the polarization state is used instead of visible light communication by blinking, so that the blinking and flickering will not be visible.

[0050] Hereinafter, an overview of a signal system 100 including a signal lamp unit 20 will be described with reference to a conceptual diagram shown in FIG.

[0051] As shown in the figure and as described above, the signal system 100 of this embodiment has a receiving device 10 constituting the vehicle-mounted side and a signal lamp unit 20 constituting the traffic light side. In the signal lamp unit 20, the polarization conversion unit 22 converts the polarization state of the light source light GL according to the signal content to be transmitted, and outputs the converted light as emitted light EL. At this time, as shown in the figure, the polarization state of the emitted light EL corresponding to one signal content 1 is switched and output according to the signal content to be transmitted. For example, the polarization state of the emitted light EL corresponding to another signal content 2 different from the signal content 1 is output as polarization state x (polarization state y ≠ polarization state x), and the polarization state of the emitted light EL corresponding to another signal content 2 different from the signal content 1 is output as polarization state y (polarization state y ≠ polarization state x). On the other hand, on the vehicle-mounted side, for example, information based on the polarization state among the components of the emitted light EL received by the camera 11 (image sensor 11s) via the vehicle-mounted polarizing plate 13 is analyzed in the signal reading unit 12s of the image processing unit 12, and the information is read. That is, the signal reader 12s restores, on the vehicle side, signal content 1 corresponding to the polarization state x and signal content 2 corresponding to the polarization state y.

[0052] As described above, the signal system 100 of this embodiment includes a polarization conversion unit 22 on the traffic light side that converts the polarization state of the light source light GL according to the signal content (for example, converting to polarization states x and y according to signal content 1 and 2) and outputs the light EL, and a signal reading unit 12s on the vehicle side that reads the signal content based on received light according to the polarization state of the output light EL. The signal system 100 enables signal transmission using switching of the polarization state, and in this case, even if the signal switching operation for communication using visible light is slow, blinking or flickering can be prevented from being visually recognized.

[0053] Second Embodiment Hereinafter, a configuration example of a signal system according to the second embodiment and the signal lamps constituting the same will be described with reference to the block diagram shown in Fig. 6. Note that Fig. 6 corresponds to Fig. 3, and components having the same functions and properties as those in the signal system 100 according to the first embodiment are indicated by the same reference numerals, and the matters explained in Fig. 3 will be referred to as necessary, and detailed explanations will be omitted.

[0054] The signal system 200 of this embodiment is different from the signal system 100 of the first embodiment in that the signal device side, i.e., the signal lamp 220, emits circularly polarized light instead of linearly polarized light as the emitted light EL. Accordingly, the receiving device 210 also transmits and absorbs (blocks) the light according to the characteristics of the circularly polarized light.

[0055] In order to realize the above-mentioned aspect, in the polarization conversion unit 222 of the signal lamp 220 of the signal system 200, a traffic light side λ / 4 wave plate 222r is provided at the rear stage of the liquid crystal panel 22p. This allows the polarization state of the emitted light PL to be emitted as circularly polarized light of different properties. In the illustrated example, the traffic light side λ / 4 wave plate 222r emits the first polarized light LLp incident with 0 degree linear polarization as right circular polarization, and the second polarized light LLs incident with 90 degree linear polarization as left circular polarization. As described above, in this embodiment, the polarization conversion unit 222 emits the polarization state of the emitted light EL as circular polarization.

[0056] On the other hand, in the signal system 200, the receiver 210 is provided with an upper-car λ / 4 wave plate 214 in front of the upper-car polarizing plate 13. The upper-car λ / 4 wave plate 214 converts the circularly polarized output light EL into linearly polarized light. More specifically, in the figure, the upper-car λ / 4 wave plate 214 outputs the first polarized light LLp component incident in a right-handed circularly polarized state as a 90-degree linearly polarized light, and outputs the second polarized light LLs component incident in a left-handed circularly polarized state as a 0-degree linearly polarized light, for the components of the output light PL from the signal lamp 220 incident on the receiver 210. In this case, the first polarized light LLp is absorbed (blocked) in the upper-car polarizing plate 13, and the second polarized light LLs is transmitted.

[0057] In the above, the case where the light is converted into circularly polarized light has been described, but the light is not limited to being circularly polarized light, and a mode in which the light is converted into elliptically polarized light is also possible.

[0058] In this embodiment, signal transmission using switching of polarization state is also possible, and in this case, even if the signal switching operation for communication using visible light is slow, blinking or flickering can be prevented from being visually recognized. In particular, in this embodiment, the polarization state of the emitted light EL when emitted from the traffic light side can be made to be a state other than linear polarization.

[0059] 〔others〕 The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit and scope of the present invention.

[0060] First, in the above, polarization and its conversion (switching) are performed using an LED light source, a polarizing plate, a liquid crystal panel, etc., but as long as the desired polarization switching is possible, various modes can be adopted without being limited to the above modes.

[0061] For example, with regard to the light source, in accordance with the use of multiple LED elements as the light-emitting section 21e, a traffic light side polarizing plate (polarizer) 22a is arranged immediately behind the light source section 21. However, it is also possible to use a light source that emits polarized light and not provide a polarizer.

[0062] In the above, for example, the polarization state is switched uniformly for the entire light source light GL from the light emitting unit 21e, and the light receiving side detects whether the polarization state is on or off, i.e., detects whether it is 0 or 1. However, the present invention is not limited to this configuration, and more complex information collection may be performed, for example, by capturing various signal contents in combination with information received as an image on the receiving side.

[0063] Also, the switching pattern of the polarization state on the transmitting side and the detection mode on the receiving side can be various. Or, the frequency of switching on the transmitting side and the frame rate on the receiving side can be variously changed according to the performance of the camera 11 used. Also, various shutter speeds for the frame rate can be considered, but as an example, a mode in which the exposure time for the length of time t corresponding to one frame is about half (about t / 2) by setting it to about 1 / 2 (1 / 60 seconds when the frame rate is 30 fps as in the above example).

[0064] In the above, as an example, the present invention has been described as being used in railways, more specifically, as being configured to read the signal contents as an automatic driving signal in the signal reading unit 12s, but the present invention is not limited to this, and it is also possible to adopt the signal system or signal lamp of the present invention as a traffic signal (in a signal lamp for automobiles). In this case, as described in the second embodiment, for example, by making the light emitted from the signal lamp circularly polarized, it is possible to maintain the function of a normal traffic signal even for a driver wearing sunglasses.

[0065] Various types of signal information are also assumed to be handled, and in the case of a railway, in addition to the above-mentioned examples, for example, the signal system 100 may be applied to transmit and receive signals for instructions to change direction at a switch. Moreover, these various signals related to railway operation may be integrated into a single signal lamp 20. This allows the entire railway signal system to be configured compactly and simply.

[0066] In addition, in the above, the signaling system 100 is applied to the operation of railway trains. However, the present invention is not limited to this. For example, the signaling system 100 can also be adopted for trams that run on tracks (new tracks, dual-use tracks) and buses that run on dedicated roads. [Explanation of symbols]

[0067] 10,210...receiving device, 11...camera (imaging unit), 11s...image sensor, 12...image processing unit, 12s...signal reading unit, 13...vehicle-side polarizing plate, 20,220...signal lamp, 20g...blue signal lamp, 20r...red signal lamp, 20y...yellow signal lamp, 21...light source unit, 21e...light emitting unit, 21s...light source control unit, 22...polarization conversion unit, 22a...traffic light side polarizing plate, 22c...polarization control unit, 22p...liquid crystal panel, 30...signal generating device, 100,200...signal system, 214...vehicle-side λ / 4 wave plate, 222...polarization conversion unit, 222r...traffic light side λ / 4 wave plate, EL...emitted light, GL...light source light, LC...lighting control unit, PB...power supply board, PL...emitted light, RL...railroad track, TR...train, α,β,γ...chart

Claims

1. a polarization conversion unit on the traffic light side that converts the polarization state of the light source light according to the content of the signal and outputs the converted light; a signal reading unit disposed on the vehicle top side, which reads the content of the signal based on received light corresponding to the polarization state of the emitted light; A signaling system comprising:

2. the polarization conversion unit switches the polarization direction of the linearly polarized light for the emitted light and emits the light; 2. The signaling system according to claim 1, further comprising an upper polarizing plate on the upper side of the vehicle that transmits the emitted light that is linearly polarized in one direction and absorbs the emitted light that is linearly polarized in another direction.

3. the polarization conversion unit outputs the emitted light as a circularly polarized light, 2. The signaling system according to claim 1, further comprising an on-board λ / 4 wave plate that converts the emitted light, which is circularly polarized, into linearly polarized light, on the on-board side of the vehicle.

4. The signal system according to claim 1 , wherein the signal reading unit reads the signal content from brightness information in the received emitted light.

5. The signal system according to claim 1 , wherein the polarization conversion unit has a liquid crystal panel that converts the polarization state of the emitted light.

6. 2. The signaling system according to claim 1, further comprising an imaging unit on an upper side of the vehicle, which captures continuous images of an external environment and receives the emitted light.

7. The signal system according to claim 6 , wherein a frequency of light conversion in the polarization conversion unit is lower than a frame rate of the imaging unit.

8. The signal system according to claim 1 , further comprising a light source unit on the signal side that emits light in a visible light wavelength band as the emitted light.

9. The signal system according to claim 1 , wherein the signal reading unit reads the signal content as a signal for automatic operation.

10. A light source unit that emits light source light; a polarization conversion unit that converts the polarization state of the light source light from the light source unit in accordance with a signal content and outputs the converted light; A signal lamp equipped with:

Images