JP2004306902A - Crossing obstruction detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate the influence of a low frequency optical noise to prevent the mutual interference with an adjacent crossing and additionally to make a detector small to reduce the restriction in installation. <P>SOLUTION: The crossing obstruction detector includes: light emitters 1a to 1e modulating carrier waves, driving light emitting elements, and emitting modulated waves with an intermittent period; and light receivers 2a to 2e receiving lights from the light emitters 1a to 1e, converting it to voltages, and taking out modulated wave components, converting them to direct currents, and outputting them. The detector raises the frequencies of the carrier waves and the modulated waves of the light emitters 1a to 1e, and prevents erroneous detection due to the low frequency optical noise such as HID lamps to surely detect the crossing obstruction such as vehicles. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention removes the influence of a railroad crossing obstacle detecting device for detecting a car, a pedestrian, and the like at a railroad crossing, particularly, a high-intensity discharge lamp (hereinafter, referred to as a HID (High Intensity Discharge) lamp) to prevent erroneous detection. In addition, the present invention relates to improving safety and reducing restrictions on installation by downsizing.
[0002]
[Prior art]
[Patent Document 1] Japanese Unexamined Patent Publication No. Hei 5-8731 [Patent Document 2] Japanese Unexamined Patent Publication No. Hei 10-76954 A railroad crossing warning device of a railway safety device starts a crossing warning when a train running on a track approaches a railroad crossing. In order to ensure the safe operation of the train and the safety of cars and pedestrians passing through the crossing, the traffic will be released immediately after the train crosses the crossing and smooth road traffic will be released. I can do it.
[0003]
As a railroad crossing obstacle detection device that detects an obstacle such as a car that hinders the safe operation of a train on this railroad crossing, as shown in Patent Literature 1 and Patent Literature 2, a plurality of lights are emitted on both sides of a railroad crossing and a track. When a train approaches and a light beam is continuously blocked for a certain period of time when a train approaches, a car, etc. It judges that there is an obstacle and notifies the train of danger.
[0004]
As shown in the block diagram of FIG. 5, the light emitting device 6 of the railroad crossing obstacle detecting device using the light beam includes an oscillator 61, a frequency divider 62, a modulator 63, an amplifier 64, and a light emitting diode (LED) 65. . The oscillator 61 excites at several kHz, for example, 5 kHz and outputs a carrier wave fc. The carrier wave fc is frequency-divided by the frequency divider 62 to generate a modulated wave fm of several hundreds Hz, for example, 250 Hz, and sends it to the modulator 63. The modulator 63 modulates the carrier wave fc with the modulation wave fm as shown in the waveform diagram of FIG. The amplifier 64 amplifies the transmitted modulated wave, drives the light emitting element (LED) 65, and emits intermittently modulated light.
[0005]
As shown in the block diagram of FIG. 7, the light receiver 7 for receiving the modulated light emitted from the LED 65 includes a light receiving unit 71, an amplifier 72, a BPF 73, a detector 74, a BPF 75, an amplifier 76, a transformer 77, and a rectifier circuit 78. Having. The light receiving unit 71 receives the modulated light from the light emitter 6 with the photodiode PD, converts the modulated light into a voltage, amplifies the voltage with the amplifier 72, removes out-of-band components with the BPF 73 of the carrier fc, and rectifies the carrier fc with the detector 74. Then, the component of the modulated wave fm is taken out by the BPF 75, the component of the modulated wave fm is amplified by the amplifier 76, the input power supply and the output section are separated by the transformer 77, and the power supply is prevented from being mixed into the output. Rectifier circuit 78 converts the signal output from the DC to DC to operate the detection relay. Then, when the light is cut off between the light emitting device 6 and the light receiving device 7, the output of the light receiving device 7 disappears, and it is determined that there is an obstacle.
[0006]
[Problems to be solved by the invention]
In recent years, the use of high-intensity discharge lamps (hereinafter, HID (High Intensity Discharge) lamps for headlights of automobiles, headlights of trains, and the like has been rapidly increasing in order to save energy and extend the life. The light spectrum extends to the near-infrared region used in the light emitting device 6 of the level crossing obstacle detection device using a light beam, and the discharge frequency is several hundred Hz. May malfunction.
[0007]
In general, an inductance L is inserted into the light receiving unit 71 to prevent the photodiode PD of the light receiving unit 71 from being saturated by DC light such as sunlight and suppressing a signal. Since the frequency of fc is low, a large inductance is required. Further, since the frequency of the modulated wave fm is low, the BPF 75 for extracting the component of the modulated wave fm also becomes large, which makes it difficult to miniaturize the apparatus.
[0008]
Further, there is a problem that it is difficult to have a plurality of modulated waves as a countermeasure for interference at an adjacent railroad crossing in view of a necessary frequency band.
[0009]
The present invention solves such a problem, eliminates the effects of low-frequency optical noise such as HID lamps, prevents mutual interference with adjacent railroad crossings, and reduces the size of the device to reduce installation restrictions. It is an object of the present invention to provide a railroad crossing obstacle detecting device capable of performing the above-mentioned.
[0010]
[Means for Solving the Problems]
A level crossing obstacle detection device according to the present invention includes a light emitting device that modulates a carrier wave to drive a light emitting element to emit modulated light having an intermittent period, and receives light from the light emitting device and converts the light into a voltage to generate a modulated wave component In a level crossing obstacle detection device having a photodetector that takes out, converts it to direct current, and outputs it, the frequency of the carrier wave and the modulation wave is increased to remove the effects of low-frequency optical noise such as HID lamps. I do.
[0011]
It is desirable that the frequency of the carrier be in a 10 MHz band.
[0012]
Further, the carrier wave is divided to generate a plurality of modulated waves having different frequencies, a modulated wave having a different frequency is selected according to an installation location, and the pulse width of the selected modulated wave is corrected according to the frequency, and the The energy is made uniform and interference between adjacent railroad crossings is prevented.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a layout diagram of a railroad crossing obstacle detection device. As shown in the figure, the railroad crossing obstacle detection device has a plurality of light emitters 1a to 1e and a plurality of light receivers 2a to 2e. The light emitters 1a to 1e and the light receivers 2a to 2e are arranged in combination on both sides of the railroad crossing path of the railroad crossing 3 and the track 4, and distribute a light beam such as near-infrared light on the railroad crossing when the train 5 approaches. When the light beams received by the light receivers 2a to 2e are continuously shielded for a certain period of time, it is determined that there is an obstacle such as an automobile on the railroad crossing, and the danger is notified to the train 5.
[0014]
As shown in the block diagram of FIG. 2, the light emitter 1 includes an oscillator 11, a frequency divider 12, a switch 13, a pulse width control circuit 14, a modulator 15, an amplifier 16, and an LED 17. The oscillator 11 outputs a carrier fc having a frequency of 10 MHz. This carrier fc is frequency-divided by the frequency divider 12 to generate a modulated wave fm1 having a frequency of 6 kHz, a modulated wave fm2 having a frequency of 10 kHz, and a modulated wave fm3 having a frequency of 14 kHz. This is because, for example, when the modulated wave fm1 is used at the railroad crossing 3, the adjacent railroad crossings are switched so that the switch 13 is used to use the modulated wave fm2 and the modulated wave fm3 so that there is no interference between the adjacent railroad crossings. .
[0015]
When a plurality of modulated waves fm1 to fm3 having different frequencies are output from the frequency divider 12 as described above, the average value of each of the modulated waves fm1 to fm3 changes greatly, and the light energy received by the light receiver 2 changes. I will. For example, as shown in the waveform diagram of FIG. 4, when the average values V1 and V2 of the modulated wave fm1 having a frequency of 6 kHz and the modulated wave fm2 having a frequency of 10 kHz are obtained,
Average value of modulated wave fm1 V1 = Vp × (tp / t1)
Average value of modulated wave fm2 V2 = Vp × (tp / t2)
The average values V1 and V2 change depending on the cycle t1 of the modulated wave fm1 = (1 / fm1) and the cycle t2 = (1 / fm2) of the modulated wave fm2. Therefore, the pulse widths of the modulated waves fm1 to fm3 output from the frequency divider 12 are corrected by the pulse width control circuit 14. For example, the pulse width of the modulated wave fm2 having the frequency of 10 kHz is 5 μs, the pulse width of the modulated wave fm1 having the frequency of 6 kHz is [5 × (10/6)] μs, and the pulse width of the modulated wave fm3 having the frequency of 14 kHz is [ 5 × (10/14)] μs.
[0016]
The carrier wave fc of 10 MHz is amplitude-modulated by the modulated wave fm having the corrected pulse width, amplified by the amplifier 16, and drives the LED 17 to emit light.
[0017]
As shown in the block diagram of FIG. 3, the light receiver 2 for receiving the light from the LED 17 includes a light receiving unit 21, an amplifier 22, a BPF 23, a detector 24, a BPF 25, a switch 26, an amplifier 27, a transformer 28, and a rectifier circuit. 29. The light receiving unit 21 has a light / voltage conversion element, for example, a photodiode PD, and receives light from the light emitter 6 with the photodiode PD and converts the light into a voltage. This voltage is amplified by the amplifier 22, the out-of-band component is removed by the BPF 23 of the carrier fc having a carrier frequency of 10 MHz, the carrier fc is rectified by the detector 24, and the components of the modulated waves fm1 to fm3 are taken out by the BPF 25. For example, the modulation wave fm1 is taken out by the switch 26 set according to the above, amplified by the amplifier 27, converted into DC through the rectifier circuit 29 from the transformer 28, and the detection relay is operated.
[0018]
The noise of the light affected by this railroad crossing obstacle detection device includes light from an inverter fluorescent lamp and an HID lamp, but the inverter frequency of the inverter fluorescent lamp is up to about 100 kHz, and there is no direct effect in terms of luminance. , The discharge frequency of the HID lamp is about 500 Hz, but since the brightness is high, the spread of its harmonics is large, and the spectrum of the light extends to the near infrared region, the conventional carrier frequency of 5 kHz, for example, is low. In this case, the influence is affected, but by using the 10 MHz band as the carrier frequency, this influence can be ignored and completely removed by the BPF 23. Therefore, it is possible to prevent the light receiver 2 from erroneously detecting due to low-frequency optical noise such as an HID lamp, and to reliably detect a level crossing obstacle such as an automobile.
[0019]
The converted voltage output from the light receiving unit 21 is obtained at both ends of the load resistance RL of the photodiode PD. However, when sunlight enters the photodiode PD, sunlight is a DC component. The signal is saturated and the signal of 10 MHz disappears. As a countermeasure against this, a method of connecting an inductance L in parallel with the load resistance RL to release a DC component is generally adopted. It is desirable that the inductance L has a small DC resistance and is sufficiently larger than the load resistance RL for signals. For example, when RL = 1 kΩ, the impedance ZL of the inductance L is ZL≫RL with respect to the signal, and ZL = 10 kΩ. When the carrier frequency is 5 kHz and 10 MHz, the inductance L at which ZL = 10 kΩ is obtained.
L (10kΩ / 5kHz) ≒ 150mH,
L (10kΩ / 10MHz) ≒ 150μH
By setting the carrier frequency to 10 MHz, the magnitude of the inductance L can be made very small.
[0020]
Further, by setting the carrier frequency to 10 MHz, a BPF having an FM broadcast frequency of 10.7 MHz can be used as the BPF 23, and the detector 23 and the BPF 24 can be downsized. It is possible to reduce installation restrictions.
[0021]
【The invention's effect】
As described above, the present invention increases the frequency of the carrier wave and the modulation wave as the driving frequency of the light emitting element to eliminate the influence of low frequency optical noise such as HID lamps. It is possible to prevent erroneous detection due to the optical noise of the vehicle and to surely detect a level crossing obstacle such as an automobile.
[0022]
In addition, by setting the frequency of the carrier wave to the 10 MHz band, the ratio between the modulation frequency and the carrier frequency can be increased, and a plurality of modulation frequencies can be obtained.
[0023]
Furthermore, by dividing the carrier wave to create a plurality of modulated waves having different frequencies, selecting a modulated wave having a different frequency according to the installation location, and correcting the pulse width of the selected modulated wave according to the frequency, the Energy can be made uniform and interference between adjacent railroad crossings can be prevented.
[0024]
In addition, by setting the frequency of the carrier wave to the 10 MHz band, the magnitude of the inductance connected in parallel with the load resistance of the light receiving element is very small in order to eliminate the effect of sunlight entering the light receiving element of the light receiving section. In addition, the size of each component such as the BPF and the detector can be reduced to reduce the size of the light receiver, and the restrictions on installation can be reduced.
[Brief description of the drawings]
FIG. 1 is a layout diagram of a railroad crossing obstacle detection device.
FIG. 2 is a block diagram illustrating a configuration of a light emitting device.
FIG. 3 is a block diagram illustrating a configuration of a light receiver.
FIG. 4 is a waveform chart showing changes in light energy due to modulated waves having different frequencies.
FIG. 5 is a block diagram showing a configuration of a conventional light emitting device.
FIG. 6 is a waveform diagram of a light emission waveform output from a light emitting device.
FIG. 7 is a block diagram illustrating a configuration of a conventional light receiver.
[Explanation of symbols]
1; light emitter, 2; light receiver, 3; railroad crossing, 4; track, 5; train, 11;
12; frequency divider, 13; switch, 14; pulse width control circuit, 15; modulator,
16; amplifier, 17; LED, 21; light receiving unit, 22;
23; BPF, 24; detector, 25; BPF, 26; switch,
27; amplifier, 28; transformer, 29; rectifier circuit.

Claims (3)

A light emitting device that modulates a carrier wave to drive a light emitting element to emit modulated light of an intermittent cycle, receives light from the light emitting device, converts the light into a voltage, extracts a modulated wave component, converts the component into a direct current, and outputs it. What is claimed is: 1. A railroad crossing obstacle detecting device having a photodetector, wherein the frequency of a carrier wave and a modulation wave is increased to remove the influence of low frequency optical noise such as an HID lamp. The railroad crossing obstacle detection device according to claim 1, wherein the frequency of the carrier wave is in a 10 MHz band. 3. The carrier wave is divided to generate a plurality of modulated waves having different frequencies, a modulated wave having a different frequency is selected according to an installation location, and a pulse width of the selected modulated wave is corrected according to the frequency. The crossing obstacle detection device according to the above.

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