JP4233371B2 - Railroad crossing obstacle detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention eliminates the influence of a crossing obstacle detection device for detecting cars, pedestrians, etc. at a railroad crossing, particularly a high-intensity discharge lamp (hereinafter referred to as a HID (High Intensity Discharge) lamp) to prevent false detection. In addition to improving safety, it is related to reduction of installation restrictions by downsizing.
[0002]
[Prior art]
[Patent Document 1]
Japanese Patent Laid-Open No. 5-8731 [Patent Document 2]
A railroad crossing warning device for a railway safety device starts a railroad crossing alarm when a train traveling on a track approaches the railroad crossing, blocks traffic on the railroad crossing, and ensures safe operation of the train and the railroad crossing. In order to ensure the safety of cars and pedestrians that pass through, the road is cut off immediately after the train has passed the railroad crossing so that smooth road traffic is possible.
[0003]
As a crossing obstacle detection device that detects obstacles such as automobiles that hinder the safe operation of trains on this railroad crossing, as shown in Patent Document 1 and Patent Document 2, a plurality of light emission on both sides across the railroad crossing and the track If the light beam of the light beam such as infrared rays is distributed on the railroad crossing and the light beam is continuously blocked for a certain time when the train approaches, Judges that there is an obstacle and notifies the train of the danger.
[0004]
The light emitter 6 of the crossing obstacle detection device using this light beam has an oscillator 61, a frequency divider 62, a modulator 63, an amplifier 64, and a light emitting diode (LED) 65, as shown in the block diagram of FIG. . The oscillator 61 is excited 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 sent to the modulator 63. The modulator 63 modulates the carrier wave fc with the modulated wave fm as shown in the waveform diagram of FIG. The amplifier 64 amplifies the transmitted modulated wave and drives the light emitting element (LED) 65 to emit modulated light having an intermittent period.
[0005]
As shown in the block diagram of FIG. 7, the light receiver 7 that receives the modulated light emitted from the LED 65 includes a light receiver 71, an amplifier 72, a BPF 73, a detector 74, a BPF 75, an amplifier 76, a transformer 77, and a rectifier circuit 78. Have The light receiving unit 71 receives the modulated light from the light emitter 6 by the photodiode PD, converts it to a voltage, amplifies it by the amplifier 72, removes the out-of-band component by the BPF 73 of the carrier wave fc, and rectifies the carrier wave fc by the detector 74. Then, the component of the modulated wave fm is extracted by the BPF 75, the component of the modulated wave fm is amplified by the amplifier 76, the input power source and the output unit are separated by the transformer 77, and the power source is prevented from being mixed into the output. The rectifier circuit 78 converts the signal output from the signal into a direct current to operate the detection relay. When the light is blocked between the light emitter 6 and the light receiver 7, the output of the light receiver 7 is lost, and there is an obstacle.
[0006]
[Problems to be solved by the invention]
In recent years, the use of high-intensity discharge lamps (hereinafter referred to as HID (High Intensity Discharge) lamps) has been rapidly increasing in order to save energy and increase the life of automobile headlights and train headlights. The optical spectrum extends to the near-infrared region used in the light emitter 6 of the railroad crossing obstacle detection device using a light beam, and the discharge frequency is several hundred Hz. May cause malfunction.
[0007]
Further, in order to prevent the photodiode PD of the light receiving unit 71 from being saturated with direct current light such as sunlight and suppressing the signal, generally, an inductance L is inserted into the light receiving unit 71. 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 becomes large, making it difficult to reduce the size of the apparatus.
[0008]
Furthermore, there is a problem that it is difficult to realize a plurality of modulated waves as countermeasures against adjacent level crossings from the viewpoint of the necessary frequency band.
[0009]
The present invention eliminates such problems, eliminates the effects of low-frequency optical noise such as HID lamps, prevents mutual interference with adjacent level crossings, and reduces the size of the device to reduce installation restrictions. An object of the present invention is to provide a crossing obstacle detection device capable of
[0010]
[Means for Solving the Problems]
The crossing obstacle detection device of the present invention divides a carrier wave having a frequency of 10 MHz to create a plurality of modulated waves having different frequencies, selects a modulated wave having a different frequency according to the installation location, and selects the modulated wave of the selected modulated wave. A light emitter that modulates a carrier wave with a modulated wave whose pulse width is corrected according to frequency and drives a light emitting element to emit modulated light of an intermittent period, and receives light from the light emitter and converts it into a voltage; And a light receiver that extracts a modulated wave component having a frequency corresponding to the installation location, converts the component into a direct current, and outputs the direct current .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a layout diagram of a crossing obstacle detection device. As shown in the figure, the 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 3 and the railroad 4, and when a light beam such as near infrared rays is distributed on the railroad crossing and the train 5 approaches When the light beams received by the light receivers 2a to 2e are shielded from light for a certain period of time, it is determined that there is an obstacle such as an automobile on the railroad crossing, and the train 5 is notified of the danger.
[0014]
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, as shown in the block diagram of FIG. The oscillator 11 outputs a carrier wave fc having a frequency of 10 MHz. The carrier fc is 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 modulation wave fm1 is used at the level crossing 3, the adjacent level crossing uses the modulation wave fm2 and the modulation wave fm3 to prevent interference between the adjacent level crossings. .
[0015]
As described above, when the plurality of modulated waves fm1 to fm3 having different frequencies are output from the frequency divider 12, 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. End up. For example, as shown in the waveform diagram of FIG. 4, when average values V1 and V2 are obtained for a modulated wave fm1 having a frequency of 6 kHz and a modulated wave fm2 having a frequency of 10 kHz, respectively.
Average value V1 of modulated wave fm1 = Vp × (tp / t1)
Average value V2 of modulated wave fm2 = Vp × (tp / t2)
Thus, the average values V1 and V2 change depending on the period t1 = (1 / fm1) of the modulated wave fm1 and the period t2 = (1 / fm2) of the modulated wave fm2. Therefore, the pulse width of the modulated waves fm1 to fm3 output from the frequency divider 12 is corrected by the pulse width control circuit 14. For example, the pulse width of the modulation wave fm2 having a frequency of 10 kHz is 5 μs, the pulse width of the modulation wave fm1 having a frequency of 6 kHz is [5 × (10/6)] μs, and the pulse width of the modulation wave fm3 having a frequency of 14 kHz is [ 5 × (10/14)] μs is corrected.
[0016]
The carrier wave fc of 10 MHz is amplitude-modulated by the modulated wave fm with the corrected pulse width, amplified by the amplifier 16, and the LED 17 is driven to emit light.
[0017]
As shown in the block diagram of FIG. 3, the light receiver 2 that receives 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 includes a light / voltage conversion element such as a photodiode PD, and receives light from the light emitter 6 by the photodiode PD and converts it 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 extracted by the BPF 25. For example, the modulated wave fm1 is taken out by the switch 26 set in accordance with the above and amplified by the amplifier 27, converted into direct current from the transformer 28 through the rectifier circuit 29, and the detection relay is operated.
[0018]
Light noise affected by this level crossing obstacle detection device includes light from an inverter fluorescent lamp or an HID lamp, but the inverter frequency of the inverter fluorescent lamp is up to about 100 kHz, and there is no direct influence from the point of brightness. The discharge frequency of the HID lamp is about 500 Hz, but the brightness is high, the spread of the harmonics is large, and the spectrum of the light extends to the near infrared region. In this case, it is affected, but by using the 10 MHz band as the carrier frequency, this influence can be ignored and can be completely removed by the BPF 23. Therefore, the light receiver 2 can be prevented from being erroneously detected by low-frequency optical noise such as an HID lamp, and a crossing obstacle such as an automobile can be reliably detected.
[0019]
The conversion voltage output from the light receiving unit 21 is obtained at both ends of the load resistor RL of the photodiode PD. When sunlight enters the photodiode PD, the sunlight is a direct current component. It becomes saturated and the 10 MHz signal disappears. As a countermeasure against this, generally, a method is adopted in which an inductance L is connected in parallel with the load resistance RL to release a direct current component. The inductance L has a small direct current resistance, and is desirably 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 when ZL = 10 kΩ, the inductance L that makes ZL = 10 kΩ at 5 kHz and 10 MHz is obtained.
L (10 kΩ / 5 kHz) ≈150 mH,
L (10kΩ / 10MHz) ≒ 150μH
Thus, the inductance L can be made very small by setting the carrier frequency to 10 MHz.
[0020]
Further, by setting the carrier frequency to 10 MHz, a BPF having a frequency for FM broadcasting of 10.7 MHz can be used as the BPF 23, and the detector 23 and the BPF 24 can be miniaturized, and the light receiver 2 can be downsized. It is possible to reduce installation restrictions.
[0021]
【The invention's effect】
As described above, the present invention generates a plurality of modulated waves having different frequencies by dividing a carrier wave having a frequency of 10 MHz, selects a modulated wave having a different frequency according to the installation location, and selects a pulse of the selected modulated wave. The carrier wave is modulated with a modulated wave whose width is corrected according to the frequency, and the light emitting element is driven to emit the modulated light of the intermittent period, and the light receiver converts the received light into a voltage and changes the frequency according to the installation location. By extracting the modulated wave component, the light energy received by the light receiver can be made uniform and interference between adjacent level crossings can be prevented.
[0022]
Further, by setting the carrier frequency 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 using the 10 MHz band as the frequency of the carrier wave, the influence of low-frequency optical noise such as HID lamps can be eliminated, and erroneous detection due to low-frequency optical noise such as HID lamps can be prevented. Crossing obstacles such as automobiles can be reliably detected.
[0024]
Also, by setting the frequency of the carrier wave to the 10 MHz band, the size of the inductance connected in parallel with the load resistance of the light receiving element is made very small in order to eliminate the influence when sunlight enters the light receiving element of the light receiving unit. In addition, it is possible to reduce the size of each component such as the BPF and the detector to reduce the size of the light receiver, thereby reducing the installation restrictions.
[Brief description of the drawings]
FIG. 1 is a layout view of a crossing obstacle detection device.
FIG. 2 is a block diagram illustrating a configuration of a light emitter.
FIG. 3 is a block diagram showing a configuration of a light receiver.
FIG. 4 is a waveform diagram showing changes in light energy due to modulated waves of different frequencies.
FIG. 5 is a block diagram showing a configuration of a conventional light emitter.
FIG. 6 is a waveform diagram of a light emission waveform output from the light emitter.
FIG. 7 is a block diagram showing 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; amplifier,
23; BPF, 24; detector, 25; BPF, 26; switch,
27; amplifier, 28; transformer, 29; rectifier circuit.

Claims (1)

Modulation by dividing a carrier wave with a frequency of 10 MHz to create a plurality of modulated waves with different frequencies, selecting a modulated wave with a different frequency according to the installation location, and correcting the pulse width of the selected modulated wave according to the frequency A light emitter that modulates a carrier wave with a wave to drive a light emitting element to emit modulated light of an intermittent period;
A light receiver that receives light from the light emitter and converts it into a voltage, takes out a modulated wave component having a frequency according to the installation location, converts it into a direct current, and outputs it;
A crossing obstacle detection device characterized by comprising:

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