Crossing obstruction detector

【0001】

[Technical field to which the invention belongs]

The present invention prevents false detection by removing the influence of a railroad crossing obstacle detection device that detects automobiles, pedestrians, etc. at a railroad crossing, particularly a high-intensity discharge lamp (hereinafter referred to as a HID (High Intensity Discharge) lamp). However, it is related to the improvement of safety and the reduction of installation restrictions by downsizing.

【0002】

[Conventional technology]

[Patent Document 1] Japanese Patent Application Laid-Open No. 5-8731 [Patent Document 2] Japanese Patent Application Laid-Open No. 10-76954 The railroad crossing warning device of a railroad crossing safety device starts a railroad crossing warning when a train traveling on an orbit approaches a railroad crossing. However, the railroad crossing will be blocked to ensure safe driving of the train and the safety of cars and pedestrians passing through the railroad crossing. I am trying to do it.

【0003】

As a railroad 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 is emitted on both sides of the railroad crossing and the track. When a light beam such as infrared rays is distributed on the railroad crossing by arranging a combination of a device and a light receiver, and the light beam continuously blocks light 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 the danger.

【0004】

As shown in the block diagram of FIG. 5, the light emitter 6 of the railroad 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. .. The oscillator 61 excites at several kHz, for example 5 kHz, and outputs the carrier wave fc. This carrier wave fc is divided by the frequency divider 62 to create a modulated wave fm of several hundred 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. 6 and sends it to the amplifier 64. The amplifier 64 amplifies the transmitted modulated wave and drives a light emitting element (LED) 65 to emit modulated light having an intermittent cycle.

【0005】

As shown in the block diagram of FIG. 7, the receiver 7 that receives 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. Has. The light receiving unit 71 receives the modulated light from the light emitter 6 with the photodiode PD, converts it into a voltage, amplifies it with the amplifier 72, removes the out-of-band component with the BPF73 of the carrier wave fc, and rectifies the carrier wave fc with the detector 74. Then, the component of the modulated wave fm is taken out by the BPF75, the component of the modulated wave fm is amplified by the amplifier 76, the input power supply and the output part are separated by the transformer 77 to prevent the power supply from being mixed in the output, and the transformer 77 The signal output from is converted to DC by the rectifier circuit 78 to operate the detection relay. Then, when the light is blocked between the light emitter 6 and the light receiver 7, the output of the light receiver 7 disappears, and it is considered that 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) for energy saving and long life in automobile headlights and train headlights has been rapidly increasing. The optical spectrum extends to the near-intensity region used in the light emitter 6 of the crossing obstacle detection device using the light beam, and the discharge frequency is several hundred Hz, so the receiver 7 is affected by the harmonics. May cause malfunction.

【0007】

Further, in order to prevent the photodiode PD of the light receiving unit 71 from being saturated by direct current such as sunlight and suppressing the signal, generally, an inductance L is inserted in the light receiving unit 71, but a carrier wave is used. Since the frequency of fc is low, a large inductance is required. In addition, since the frequency of the modulated wave fm is also low, the BPF75 that extracts the component of the modulated wave fm becomes large, which makes it difficult to miniaturize the device.

【0008】

Further, there is a problem that it is difficult to have a plurality of modulated waves as a countermeasure against interference at an adjacent railroad crossing from the viewpoint of the required frequency band.

【0009】

The present invention solves such a problem, eliminates the influence 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 detection device capable of performing.

【0010】

[Means for solving problems]

The crossing obstacle detection device of the present invention has a light emitter that modulates a carrier wave and drives a light emitting element to emit modulated light having an intermittent cycle, and receives light from the light emitter and converts it into a voltage to convert a modulated wave component. In a crossing obstacle detection device that has a receiver that takes out and converts it to DC and outputs it, it is characterized by increasing the frequency of the carrier wave and the modulated wave to eliminate the influence of low-frequency optical noise such as HID lamps. To do.

【0011】

It is desirable that the frequency of the carrier wave be in the 10 MHz band.

【0012】

Further, the carrier wave is divided to create a plurality of modulated waves having different frequencies, a modulated wave having a different frequency is selected according to the installation location, the pulse width of the selected modulated wave is corrected according to the frequency, and light is used. It equalizes the energy and prevents interference between adjacent crossings.

【0013】

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a layout drawing 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. Light emitters 1a to 1e and receivers 2a to 2e are arranged in combination on both sides of the railroad crossing 3 and track 4, and when a light beam such as near infrared rays is distributed on the railroad crossing and the train 5 approaches. If the light beam received by the light receivers 2a to 2e is continuously blocked for a certain period of time, it is determined that there is an obstacle such as a car on the railroad crossing, and the train 5 is notified of the danger.

【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 wave fc having a frequency of 10 MHz. This carrier wave fc is divided by the divider 12 to create 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 a modulated wave fm1 is used at a railroad crossing 3, at an adjacent railroad crossing, the switch 13 is switched to use the modulated wave fm2 and the modulated wave fm3 so that the adjacent railroad crossings do not interfere with each other. ..

【0015】

When a plurality of modulated waves fm1 to fm3 having different frequencies are output from the frequency divider 12 in this way, the average value of each modulated wave fm1 to fm3 changes significantly, and the light energy received by the receiver 2 changes. It ends up. For example, as shown in the waveform diagram of FIG. 4, when the average values V1 and V2 are obtained for the modulated wave fm1 having a frequency of 6 kHz and the modulated wave fm2 having a frequency of 10 kHz, respectively, the average value V1 = Vp × (tp /) of the modulated wave fm1. t1) The average value V2 = Vp × (tp / t2) of the modulated wave fm2, and the average value V1 by the period t1 = (1 / fm1) of the modulated wave fm1 and the period t2 = (1 / fm2) of the modulated wave fm2. V2 changes. 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 modulated wave fm2 with a frequency of 10 kHz is 5 μs, the pulse width of the modulated wave fm1 with a frequency of 6 kHz is [5 × (10/6)] μs, and the pulse width of the modulated wave fm3 with a frequency of 14 kHZ is [ Correct as 5 × (10/14)] μs.

【0016】

The 10 MHz carrier wave fc is amplitude-modulated by the modulated wave fm corrected for this 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 receiver 2 that receives the light from the LED 17 includes the receiver 21, the amplifier 22, the BPF 23, the detector 24, the BPF 25, the switch 26, the amplifier 27, the transformer 28, and the rectifier circuit. Has 29. The light receiving unit 21 has an optical / voltage conversion element, for example, 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 BPF23 of the carrier wave fc with a carrier frequency of 10 MHz, the carrier wave fc is rectified by the detector 24, the components of the modulated waves fm1 to fm3 are taken out by the BPF25, and the installation location. For example, the modulated wave fm1 is taken out by the switch 26 set according to the above, amplified by the amplifier 27, converted into DC from the transformer 28 via the rectifier circuit 29, and the detection relay is operated.

【0018】

Light noise affected by this crossing obstacle detection device includes light from inverter fluorescent lamps and HID lamps, but the inverter frequency of inverter fluorescent lamps is up to about 100 kHz, and there is no direct effect in terms of brightness. , The discharge frequency of HID lamps is about 500Hz, but the brightness is high, the spread of its harmonics is large, and the spectrum of the light extends to the near infrared region, so the conventional carrier frequency is as low as 5kHz. In this case, it is affected, but by using the 10 MHz band as the carrier frequency, this effect can be ignored and completely eliminated by BPF23. Therefore, it is possible to prevent the receiver 2 from erroneously detecting due to low-frequency light noise such as a HID lamp, and it is possible to reliably detect a railroad crossing obstacle such as an automobile.

【0019】

Further, the conversion voltage output from the light receiving unit 21 is obtained at both ends of the load resistance RL of the photodiode PD, but when sunlight enters the photodiode PD, the photodiode PD is a DC component because the sunlight is a DC component. It saturates and loses the 10MHz signal. As a countermeasure, generally, an inductance L is connected in parallel with the load resistor RL to allow the DC component to escape. It is desirable that this inductance L has a small DC resistance and is sufficiently larger than the load resistance RL for signals. For example, when RL = 1kΩ, the impedance ZL of the inductance L is ZL >> RL for the signal, and when ZL = 10kΩ, the inductance L at which the transfer frequencies are 5kHz and 10MHz is ZL = 10kΩ. 5kHz) 150mH, L (10kΩ / 10MHz) 150μH, and the magnitude of the inductance L can be made very small by setting the transport frequency to 10MHz.

【0020】

In addition, by setting the carrier frequency to 10 MHz, it is possible to use a BPF with a frequency of 10.7 MHz for FM broadcasting as the BPF 23, and the detector 23 and BPF 24 can also be miniaturized, and the receiver 2 can be miniaturized. , Installation restrictions can be reduced.

【0021】

[Effect of the invention]

As described above, the present invention increases the frequencies of the carrier wave and the modulated wave as the drive frequency of the light emitting element to eliminate the influence of low-frequency optical noise such as the HID lamp. Therefore, the low frequency of the HID lamp or the like is eliminated. It is possible to prevent erroneous detection due to the light noise of the vehicle, and it is possible to reliably detect a crossing obstacle such as an automobile.

【0022】

Further, 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 made large, and a plurality of modulation frequencies can be obtained.

【0023】

Furthermore, by dividing the carrier wave to create multiple modulated waves with different frequencies, selecting modulated waves with different frequencies according to the installation location, and correcting the pulse width of the selected modulated waves according to the frequency, the light It is possible to equalize the energy and prevent interference between adjacent crossings.

【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 made very small in order to eliminate the influence of sunlight entering the light receiving element of the light receiving part. In addition, each component such as a BPF and a detector can be miniaturized to miniaturize the receiver, and installation restrictions can be reduced.

[Simple explanation of drawings]

FIG. 1 is a layout diagram of a railroad crossing obstacle detection device.

FIG. 2 is a block diagram showing a configuration of a light emitter.

FIG. 3 is a block diagram showing a configuration of a 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 emitting waveform output by a light emitter.

FIG. 7 is a block diagram showing a configuration of a conventional receiver.

[Explanation of symbols]

1; light emitter, 2; receiver, 3; crossing, 4; orbit, 5; train, 11; oscillator, 12; divider, 13; switch, 14; pulse width control circuit, 15; modulator, 16; Amplifier, 17; LED, 21; Receiver, 22; Amplifier, 23; BPF, 24; Detector, 25; BPF, 26; Switch, 27; Amplifier, 28; Transformer, 29; Rectifier circuit.