JP5306133B2 - Railroad crossing warning sound generator - Google Patents

Description

  The present invention relates to a railroad crossing warning sound generating device that is connected via an outdoor cable to a speaker attached to an alarm column beside a railroad crossing toward a railroad crossing, and generates a warning sound on the speaker. The present invention relates to a technology for realizing a failure detection function for detecting a failure state including a speaker.

  A basic conventional level crossing warning sound generator 10 without a failure detection function (see, for example, Non-Patent Documents 1 and 2 and FIG. 3 (a)) has two exteriors installed toward a railroad crossing road. A sound generation signal generating circuit 15 for generating a main signal B for level crossing alarm according to a binary logic level crossing condition A given from the outside in order to generate an alarm sound by being connected to the attached speakers 7 and 8, and a level crossing alarm The driving circuit 12 for amplifying the main signal B for power and sending it to the driving lines of the speakers 7 and 8 and the driving lines of the speakers 7 and the speakers 8 to drive the plurality of speakers 7 and 8 that can be externally connected individually. The parallel connection part 11 which connected these drive lines inside the apparatus is provided.

  The sound signal generation circuit 15 generates an oscillation signal f1 of 750 Hz when the level crossing condition A is on and stops oscillation when the level crossing condition A is off, and an oscillation signal fm of slightly over 2 Hz when the level crossing condition A is on. An oscillation circuit 19b that generates and stops oscillation when the level crossing condition A is off, an oscillation circuit 19c that generates an oscillation signal f2 of 700 Hz when the level crossing condition A is on and stops oscillation when the level crossing condition A is off, and an oscillation signal f1 An amplitude modulation circuit 17 that modulates the amplitude with the oscillation signal fm, an amplitude modulation circuit 18 that modulates the oscillation signal f2 with the oscillation signal fm, and the output signals 17 and 18 of both circuits are overlapped to generate the main signal B for the crossing warning. The crossing alarm A is turned on in order to generate a crossing warning sound when the level crossing condition A is ON. It was taken at z strong, crossing condition A is adapted to take a constant value crossing alarm for main signal B order not to issue a crossing warning sound when off.

  The drive circuit 12 includes a power amplifier 14 formed of, for example, a power amplifier, and an output transformer 13 that performs DC insulation and impedance matching. When the level crossing warning main signal B takes a constant value, the driving voltage of the speakers 7 and 8 becomes 0V and no warning sound is generated, but when the level crossing warning main signal B is in an oscillating state. The driving voltage of the speakers 7 and 8 has a sine waveform that swings positively and negatively with an amplitude of 20 Vp-p, for example, and an alarm sound that is familiar with a crossing is emitted from the speakers 7 and 8.

In the case of providing a failure detection function to such a crossing warning sound generator, conventionally (see FIG. 3B), a current transformer 21 is attached to the driving line of the speaker 7 to detect the speaker driving current C, Failure detection has been performed by performing level detection on the detection signal to determine the presence or absence of the speaker drive current C (hereinafter, the speaker 8 and its drive line are not shown).
Further, for example (Patent Document 1), a sub-signal for inspection having a smaller amplitude and higher frequency than the main signal for level crossing warning is superimposed on the main signal for level crossing warning, and the divided voltage is obtained by inserting and connecting a series impedance to a speaker drive line. Developed a crossing warning sound generator that can detect the normal state, disconnection fault and short-circuit fault related to the connection with the speaker by obtaining the sub-signal detection signal corresponding to the sub-signal for inspection from Has been.

Japanese Patent Application No. 2008-262419

Introduction to Electricity for Railway Engineers Signal Series "Level Crossing Safety Equipment" 4th Edition, Japan Railway Electric Association, published on October 30, 1997, p. 21-22 "Signal" 17th edition by Hiroshi Yoshimura and Saburo Yoshikoshi, Koyusha Co., Ltd., issued July 20, 1991, p. 479-480

However, in such a conventional level crossing warning sound generator, failure detection related to connection with a speaker is performed exclusively within the level crossing warning sound generator 10. For this reason, when a problem occurs in the speaker 7 or its outdoor cable 7a, it is detected if it is reflected in the speaker drive current C, but failure detection does not function unless it is reflected in the speaker drive current C.
Therefore, in order to ensure completeness, it is required to detect the alarm sound itself emitted from the speaker 7. To meet such a request (see FIG. 3C), for example, a microphone or the like near the speaker 7. It is conceivable that a sound sensor element 22 is installed to detect an alarm sound, and a level detection is performed on the detection signal D to determine the presence or absence of a failure.

  By the way, in a situation where the speaker 7 attached to the alarm device and the railroad crossing warning sound generator 10 not attached to the alarm device are separated and connected by the outdoor cable 7a, an alarm is provided by a normal mounting method. In order to transmit the sound detection signal D from the sound sensing element 22 to the railroad crossing warning sound generator 10, it is necessary to additionally wire another outdoor cable 25 from the sound sensing element 22 to the main body unit 10. Further, when the amplifier circuit 23 is added to the sound sensing element 22, an additional wiring for the feeder line 24 is also required. Even when level detection and determination are performed not on the railroad crossing warning sound generation device 10 but on the sound sensing element 22 side on the alarm device, additional wiring of the feeder line 24 is necessary in a normal manner.

However, additional wiring for signal transmission outdoor cables and feeders is heavy on both sides, so we want to avoid it. On the other hand, the straightforward way to eliminate the need for signal transmission wiring is the use of wireless communication. However, reliable wireless communication is expensive and difficult to use, and even if signal transmission wiring can be eliminated. The power line cannot be lost.
Therefore, it is a technical problem to realize a railroad crossing warning sound generating device that can detect a failure based on direct detection of a railroad crossing warning sound without performing additional wiring of an outdoor cable. Further, it is a further technical problem to make improvements so that additional wiring of the feeder line is not required.

  The railroad crossing warning sound generation device of the present invention (Solution 1) was created to solve such a problem, and is connected to a speaker installed toward a railroad crossing road with an outdoor cable. A sound pressure detection signal detected by a main body for generating an alarm sound in the speaker by flowing a speaker drive current to the speaker via the outdoor cable, and a sound sensing element provided near the speaker. A feedback signal that can be discriminated from a drive current is converted into a signal return unit that transmits the feedback signal via the outdoor cable, and the feedback signal is extracted from the signal transmitted through the outdoor cable, and a failure determination is performed based on the extracted feedback signal. A signal return unit.

  Further, the railroad crossing warning sound generating device of the present invention (Solution means 2) is the railroad crossing warning sound generating device of the above-mentioned solution means 1, and is a power source that receives the speaker driving current and generates the operating power of the signal return unit. A circuit is provided.

  Further, the railroad crossing warning sound generating device of the present invention (Solution means 3) is a railroad crossing warning sound generating device of the above solving means 1 and 2, wherein the main body generates a main signal for a railroad crossing warning according to a crossing condition. A sound generation signal generating circuit, an inspection signal generating circuit for generating an inspection sub-signal having a smaller amplitude and a higher frequency than the main signal for crossing warning, and a superimposed signal of the main signal for crossing warning and the sub-signal for inspection And a driving circuit that generates the speaker driving current by amplifying the signal, and the signal return unit converts the component of the inspection sub-signal when the sound pressure detection signal is converted into the feedback signal. However, the crossing warning main signal component is removed.

  Further, the railroad crossing warning sound generator of the present invention (solution 4) is the railroad crossing warning sound generator of the above solution 3, wherein the sound generation signal generation circuit and the inspection signal generation circuit are for the crossing warning. The present invention is characterized in that it is embodied in a circuit including a sound source memory that stores and holds waveform data relating to a main signal and the sub signal for inspection in waveform separation mode data formation or waveform superposition mode data formation.

  Further, the railroad crossing warning sound generator of the present invention (solution 5) is the railroad crossing warning sound generator of the above solutions 3-4, wherein the signal return unit has the same frequency as the sub-signal for inspection. A sub-signal detection signal is generated from the feedback signal by frequency conversion, and a signal for failure determination is generated by synchronous detection from the sub-signal detection signal and the inspection sub-signal. .

  Further, the railroad crossing warning sound generating apparatus of the present invention (solving means 6) is the railroad crossing warning sound generating apparatus of the above-mentioned solving means 3 to 5, wherein the inspection sub-signal component is extracted from the speaker driving current and A power supply circuit for generating operating power of the signal return unit is provided.

  In such a crossing warning sound generator of the present invention (Solution 1), the sound pressure detection signal becomes a return signal that can be discriminated from the speaker drive current, and is sent back through the outdoor cable. Thus, it is possible to realize a railroad crossing warning sound generating device capable of performing failure detection based on direct detection of a railroad crossing warning sound without performing additional wiring of an outdoor cable from the sound sensing element to the main body. Is resolved.

  Further, in the railroad crossing warning sound generating device of the present invention (Solution means 2), since the operating power of the signal return unit is covered by the speaker drive current, the addition of a feeder line from the outside to the signal return unit is added. Since it is not necessary to perform wiring, the further technical problem mentioned above is solved.

  Further, in the crossing warning sound generating device of the present invention (Solution means 3), it is not a main signal for a crossing warning that changes greatly in a pulsating manner at a relatively low frequency according to the rules relating to a crossing warning, and its amplitude is smaller than that. By generating a sub-signal for inspection that does not undesirably affect the alarm sound due to its high frequency and using it for fault detection, the detection operation is stabilized and not only when the crossing warning sound is emitted. Even when the railroad crossing warning sound is not emitted, failure detection can be performed by driving the speaker with the sub signal for inspection.

  In the crossing warning sound generator of the present invention (solution 4), waveform data relating to the main signal for crossing warning and the sub signal for inspection is stored and held in the sound source memory. Since the circuit and the inspection signal generation circuit are integrated, the circuit is simplified, and the correctness state of both circuits, and therefore the generation state of the main signal for crossing warning and the generation state of the inspection sub signal always coincide, Since the output state of the level crossing warning sound by the main signal for level crossing warning is accurately reflected in the failure detection based on the sub signal for inspection, even if the sub signal for inspection is used, the sound signal is generated due to the failure of the inspection signal generation circuit Since there is no room for missing a circuit or other fault, the fault can be accurately detected.

  In the railroad crossing warning sound generator of the present invention (solution 5), when converting the sound pressure detection signal into a feedback signal that can be distinguished from the speaker drive current, it is possible to perform simpler frequency conversion such as orthogonal code conversion. In addition to generating a feedback signal that can be discriminated in frequency, and generating a signal for failure determination by synchronous detection from the sub-signal detection signal and the inspection sub-signal, in addition to removing noise of different frequencies Since noise with different phases is also removed, the S / N ratio (signal-to-noise ratio) is improved, so that the sub-signal for inspection is weak and the sub-signal detection signal derived therefrom has to be weak. Even so, failure detection is performed accurately.

  In the crossing warning sound generator of the present invention (solution 6), the operating power of the signal return unit is generated from the component of the sub-signal for inspection that is easy to stabilize because the amplitude and the frequency are less restricted. As a result, it is not necessary to perform additional wiring of the power supply line from the outside to the signal return section, and the supplied power is stabilized even if the power supply circuit is simple.

The circuit structure of a railroad crossing warning sound generator is shown about Example 1 of the present invention, (a) is a block diagram of a signal return part, and (b) is a block diagram of a signal return part. FIG. 7 shows a circuit structure of a railroad crossing warning sound generating apparatus according to the second embodiment of the present invention, where (a) is a block diagram of a signal return unit, (b) is a block diagram of a sound signal generation circuit, and (c) is a signal return unit. FIG. (A) is a block diagram showing a circuit structure of a conventional railroad crossing warning sound generating device, (b) is a block diagram showing a circuit structure of a conventional general warning sound generating device with a failure detection function, and (c) is from a speaker. It is a block diagram of the straightforward structure assumed when detecting the emitted alarm sound itself and performing failure detection.

About such a crossing warning sound generating apparatus of the present invention, a specific form for carrying out this will be described by the following Examples 1-2.
The embodiment 1 shown in FIG. 1 embodies the above-described solving means 1 and 2 (claims 1 and 2 as originally filed), and the embodiment 2 shown in FIG. To 6 (claims 3 to 6 as originally filed).
In addition, since the same reference numerals are given to the same constituent elements as those in the past in the illustration thereof, and what is described in the background art section is also common to the following embodiments, it is redundant. The description of this will be omitted, and the following description will focus on differences from the prior art.

  About the Example 1 of the railroad crossing warning sound generator of this invention, the specific structure is demonstrated referring drawings. 1A and 1B show a circuit structure of a railroad crossing warning sound generating apparatus 100, where FIG. 1A is a block diagram of a signal return unit 30 and FIG. 1B is a block diagram of a signal return unit 40.

The railroad crossing warning sound generator 100 is a basic conventional railroad crossing warning sound generator 10 having no fault detection function, which is provided with a fault detection function. A failure detection circuit including a signal return unit 30 and a signal return unit 40 is added after the sound signal generation circuit 15 and the drive circuit 12 are taken over as they are.
In the following description, the description of the parallel connection unit 11 and the speaker 8 is omitted, but it is solely for the sake of simplification and does not exclude the presence of the parallel connection unit 11 or the connection of the speaker 8.

  The signal return unit 30 (see FIG. 1A) is housed in a small casing different from the main body unit 10, and is inserted between the outdoor cable 7a and the speaker 7 to be connected to the both. At the same time, it is attached to a level crossing alarm. The speaker 7 may be directly attached, but if it is desired to separate the speaker 7 for some reason, a short cable 7b that can withstand outdoor use is introduced, and the outdoor cable 7a is slightly extended and connected to the speaker 7. Also good. In addition, the above-described sound sensing element 22 is also a set, and is also connected to the sound sensing element 22 attached to a part on the railroad crossing alarm that is sensitive to the sound emitted from the speaker 7. The sound sensing element 22 may be directly attached or a short cable connection.

Inside the signal return section 30, an amplifier circuit 31, a frequency conversion circuit 32, a coupling transformer 33, and a power supply circuit 34 are provided.
The amplifier circuit 31 is composed of, for example, a differential amplifier circuit using an operational amplifier, and generates a sound pressure detection signal D by amplifying the signal of the sound sensing element 22. The frequency fk of the sound pressure detection signal D is the same frequency fk as that of the speaker drive current C. Specifically, 700 Hz, 750 Hz, and a little over 2 Hz are mixed. Harmonic components are mostly negligible because they are contained only a little, but may be removed by a low-pass filter or the like. .

  The frequency conversion circuit 32 includes a modulation circuit including, for example, a multiplication circuit (×) and a band pass filter (BPF), and modulates a carrier wave formed of a sine wave having a high frequency fo of 50 kHz, for example, with the sound pressure detection signal D. Thus, the sound pressure detection signal D is converted into a feedback signal E having a different frequency, eg, fo + fk. The feedback signal E having the frequency fo + fk can be easily discriminated from the speaker driving current C having the frequency fk, and neither the speaker 7 nor the sound sensing element 22 reacts or responds.

The coupling transformer 33 has a primary side connected to the output side of the frequency conversion circuit 32, and a secondary side connected to an extension line portion interposed between the outdoor cable 7a and the speaker 7, and a feedback signal via the outdoor cable 7a. E is to be transmitted.
The power supply circuit 34 includes, for example, a rectifier circuit, a smoothing circuit, and a constant voltage circuit, and generates DC power from an AC signal. The input side is connected to the extension portion of the cable 7a described above, and there The speaker driving current C is received from the signal generator, and the operating power of the signal sending unit 30 is generated. Specifically, power is supplied to the amplifier circuit 31 and the frequency conversion circuit 32.

The signal return unit 40 may be disposed separately from the main body unit 10 incorporating the sound signal generation circuit 15 and the drive circuit 12 inherited from the conventional product. In this example, the housing of the main body unit 10 is provided. And is integrated with the main body 10.
Inside the signal reduction unit 40, an input transformer 41, an amplifier circuit 42, a band pass filter 43 (BPF), a frequency conversion circuit 44, a level detection circuit 45, and a determination circuit 46 are provided.

The input transformer 41 is connected to the drive line on the output side of the drive circuit 12 on the primary side, and detects the superimposed signal E & C of the feedback signal E and the speaker drive current C transmitted through the outdoor cable 7a. Is connected to the secondary side of the input transformer 41, and the superimposed signal E & C is appropriately amplified and sent to the band-pass filter 43.
In the frequency component of the superimposed signal E & C, the frequency fk of the speaker driving current C and the frequency fo + fk of the feedback signal E are mixed.

The bandpass filter 43 passes an appropriate frequency band centered on the frequency fo + fk, and extracts the component of the feedback signal E from the superimposed signal E & C.
The frequency conversion circuit 44 is composed of a demodulation circuit including, for example, an envelope detection circuit (detection) and a bandpass filter (BPF), and removes a carrier wave of the frequency fo from the feedback signal E of the frequency fo + fk to thereby reduce the sound pressure of the frequency fk. A reproduction signal F is generated.
Since this sound pressure reproduction signal F is a reproduction of the above-described sound pressure detection signal D, it is a signal that can determine the presence or absence of a failure by performing level detection on it.

The level detection circuit 45 is composed of, for example, a low-pass filter, and detects the signal level from the sound pressure reproduction signal F. In the present embodiment, since it was desired to clearly indicate that the sound pressure detection signal D is reproduced as the sound pressure reproduction signal F, the frequency conversion circuit 44 and the level detection circuit 45 have been described separately. 44 and the level detection circuit 45 may be integrated.
The determination circuit 46 is composed of, for example, a comparator with hysteresis characteristics, and determines whether or not there is a failure depending on whether the level of the sound pressure reproduction signal F is above or below an appropriate threshold, but the speaker drive current C is output. Judgment comes out only when you are.

  The use mode and operation of the railroad crossing warning sound generating apparatus 100 of the first embodiment will be described.

Since the signal return unit 40 of the level crossing warning sound generator 100 is incorporated in the main body 10 to which one end of the outdoor cable 7a is connected or connected, the conventional level crossing alarm sound generating device can be replaced with the main body 10. If it is installed, it is connected with the outdoor cable 7a.
On the other hand, since the signal return part 30 is separated from the main body part 10, it is installed near the speaker 7 to which the other end of the outdoor cable 7a is connected or connected, and the other end of the outdoor cable 7a. It is inserted between the speaker 7 and connected to both. A sound sensing element 22 is also connected.
If the outdoor cable 7a is laid, the other outdoor cable (25) which connects the signal return part 30 and the signal return part 40 is unnecessary, and the feed line (24) of the signal return part 30 is also unnecessary.

  In the railroad crossing warning sound generating device 100 thus simply installed, the sounding signal generation circuit 15 and the drive circuit 12 operate as in the conventional case, and when the level crossing condition A is OFF, the sounding signal generation circuit 15 Since the alarm main signal B is set to a constant value and the speaker drive current C is not output from the drive circuit 12, no alarm sound is emitted from the speaker 7. On the other hand, when the level crossing condition A is on, the sound generation signal generation circuit 15 Since the main signal B is oscillated and the speaker drive current C having the frequency fk is output from the drive circuit 12, an alarm sound that can be heard from the speaker 7 is emitted.

  On the other hand, unlike the conventional case, the signal return unit 30 attached to the speaker 7 and the signal return unit 40 built in the main body unit 10 are operated, but when the installation level crossing condition A is off and the speaker drive current C is not output, Since the power supply circuit 34 cannot supply operating power, the signal return unit 30 does not operate, and even if the signal return unit 30 operates, the determination circuit 46 of the signal return unit 40 performs determination when there is no speaker drive current C. Because there is no failure, it is not erroneously judged as a failure. Therefore, when the installation level crossing condition A is OFF, only an alarm sound is not emitted.

  On the other hand, when the railroad crossing condition A is ON and the speaker drive current C is output, the power supply circuit 34 receives the power and supplies power, so that the signal return unit 30 operates. When an alarm sound is emitted from the speaker 7 by the speaker drive current C, the sound sensing element 22 responds to it, and the signal return unit 30 obtains the sound pressure detection signal D of the frequency fk, and reflects it. The signal E is generated by the modulation process of the frequency conversion circuit 32. Since the feedback signal E has a high frequency fo + fk, it does not affect the alarm sound emitted by the speaker 7, and is transmitted to the main body 10 via the outdoor cable 7 a and reaches the signal return unit 40.

In the signal reduction unit 40, the feedback signal E is extracted from the superimposed signal E & C by frequency discrimination of the bandpass filter 43 and the like, and the frequency conversion is performed by the demodulation processing of the frequency conversion circuit 44 to generate the sound pressure reproduction signal F having the frequency fk. Failure detection is performed based on the level of the sound pressure reproduction signal F.
When the alarm sound is emitted at a sufficient volume, the signal level of the sound pressure reproduction signal F exceeds the threshold value, and it is determined that there is no failure. On the other hand, when the alarm sound is low or not at all, the signal level of the sound pressure reproduction signal F falls below the threshold value, and it is determined that there is a failure.
Thus, the failure detection based on the direct detection of the crossing warning sound is accurately performed.

  About the Example 2 of the railroad crossing warning sound generator of this invention, the specific structure is demonstrated referring drawings. 2 shows a circuit structure of the railroad crossing warning sound generator 200, where (a) is a block diagram of the signal return unit 50, (b) is a block diagram of the sound signal generation circuit 60, and (c) is a signal return unit 70. FIG.

  The railroad crossing warning sound generating device 200 is different from the railroad crossing warning sound generating device 100 of the first embodiment described above because the signal return unit 30 uses the sub-signal G for inspection instead of the speaker driving current C for failure detection. The point that the signal sending unit 50 is modified (see FIG. 2 (a)), the point that the sound signal generation circuit 15 is remodeled to become the sound signal generation circuit 60 (see FIG. 2 (b)). The signal return unit 40 has been modified to become a signal return unit 70 (see FIG. 2C).

A signal return unit 50 is installed near the speaker 7 and is inserted between the outdoor cable 7a and the short cable 7b to input a detection signal of the sound sensing element 22, or a sound signal generation circuit 60 and a signal return unit. The point that 70 is built in the main body 10 together with the drive circuit 12 is not changed.
The sub-signal G for inspection is a sine wave having a constant frequency fs and a constant amplitude, and the frequency fs is selected from a position close to an inaudible frequency within a range in which the speaker 7 can follow and emit sound, for example, 15 kHz. It is. As for the amplitude of the inspection sub-signal G, even if the inspection sub-signal G is emitted from the speaker 7 and is output on the railroad crossing, the hearing is hindered by the masking effect of a large acoustic warning sound by the main signal B for crossing warning. It is smaller than the amplitude of the main signal B for crossing warning.

  The sound signal generation circuit 60 (see FIG. 2B) also serves as an inspection signal generation circuit for generating such an inspection sub-signal G. The waveform data of the inspection sub-signal G and the level crossing alarm described above. The sound source memory 61 that stores and holds the waveform data of the main signal B for use in a data format that can be read simultaneously in parallel, and the main signal B for crossing warning and inspection when accessed and at least when the crossing condition A is on A reproduction circuit 62 that generates a sub signal G for use and an addition / synthesis circuit 63 that sends both signals together to the drive circuit 12 are provided. Thereby, the speaker drive current C sent from the drive circuit 12 to the speaker 7 and the signal return unit 50 via the outdoor cable 7a is derived from the main signal B for level crossing warning into a main signal having a low frequency fk and a large amplitude. This is a signal obtained by superimposing a sub-signal having a high frequency fs and a small amplitude derived from the inspection sub-signal G.

The signal return unit 50 (see FIG. 2A) is different from the signal return unit 30 described above in that the frequency conversion circuit 32 becomes a frequency conversion circuit 52 and the power supply circuit 34 becomes a power supply circuit 54. Is a point.
The power supply circuit 54 is preceded by a band-pass filter or the like that passes a signal component of the frequency fs, and is derived from the sub-signal G for inspection that is more stable than the main signal B for crossing warning in the speaker drive current C. The operating power of the amplification circuit 31 and the frequency conversion circuit 52 is generated from the signal component of the frequency fs.

  The frequency conversion circuit 52 may be a modulation circuit similar to the frequency conversion circuit 32. However, the frequency conversion circuit 52 converts a signal with a frequency fs into a signal with a frequency fo-fs. The component of the sub signal G for use is converted into a feedback signal E of about 35 kHz, and the component of the main signal B for crossing warning having a frequency fk such as 700 Hz is removed during the conversion process. The feedback signal E having the frequency fo-fs can also be easily discriminated from the frequency fk or the speaker driving current C having the frequency fs, and neither the speaker 7 nor the sound sensing element 22 reacts or responds. ing.

  The signal returning unit 70 (see FIG. 2C) includes a frequency fk component derived from the main signal B for crossing warning, a frequency fs component derived from the inspection sub-signal G, and a frequency fo-fs component derived from the feedback signal E. Is substantially the same as the signal reduction unit 40 in that the feedback signal E having the frequency fo-fs is extracted from the superimposed signal E & C & G in which the input transformer 41, the amplifier circuit 42, and the bandpass filter 73 are mixed. However, the frequency conversion circuit 44 and the level detection circuit 45 are changed to a frequency conversion circuit 74, a phase adjustment circuit 75, and a synchronous detection circuit 76 for improving performance, and the determination circuit 46 is expanded in function to determine the determination circuit 77. It differs from the signal reduction part 40 by the point which became.

The frequency conversion circuit 74 may be embodied by either a demodulation circuit similar to the frequency conversion circuit 44 or a modulation circuit similar to the frequency conversion circuits 32 and 52. In short, the frequency is the same as that of the inspection sub-signal G. A sub-signal detection signal H having a frequency fs is generated from the extracted feedback signal E by frequency conversion.
The phase adjustment circuit 75 is embodied by a waveform shaping circuit or a delay circuit, for example, and generates a synchronous detection signal in phase with the sub-signal detection signal H by shifting the phase of the test sub-signal G by an appropriate amount. Is.

The synchronous detection circuit 76 includes, for example, a multiplication circuit (×) and a low-pass filter (LPF). From the sub-signal detection signal H from the frequency conversion circuit 74 and the synchronous detection signal from the phase adjustment circuit 75, a determination circuit 77 is provided. A level detection signal for use in failure determination is generated.
The determination circuit 77 determines that there is no sound when the level detection signal is almost zero, determines that the level detection signal is lower than the lower limit threshold, and determines that the level detection signal is excessive when the level detection signal exceeds the upper limit threshold. If the level detection signal is between both threshold values, it is determined that there is no failure.

  Such a crossing warning sound generator 200 is used in the same manner as the crossing warning sound generator 100 described above. However, in the case of the crossing warning sound generator 200, the main signal B for crossing warning has a different frequency and amplitude. Since failure detection is performed using the sub-signal G, the operation and performance are different in several points.

  That is, when the level crossing condition A is on, the sound signal generation circuit 60 superimposes the sub signal G for inspection with the frequency fs on the main signal B for level crossing warning with the frequency fk, and the speaker from the drive circuit 12 through the outdoor cable 7a. 7 includes not only a signal of frequency fk but also a signal of frequency fs, but since the signal of frequency fs is weak, the check sound emitted from speaker 7 is a large acoustic signal. It is masked by the alarm sound of the frequency fk emitted by, and is hardly audible by the human ear. Therefore, also in this case, if there is no failure, an appropriate alarm sound that can be heard is emitted from the speaker 7. However, since the sound sensing element 22 is different in characteristics from human hearing, not only the alarm sound but also the check sound is accurately detected and converted into an electric signal.

  Further, since the generation of the inspection sub-signal G by the sound signal generation circuit 60 is performed in parallel with the generation of the main signal B for the crossing warning by sharing the sound source memory 61, the main signal B for the crossing warning and the auxiliary sub-signal for inspection are generated. The signal G is always generated in the same state. And since both signals B and G are superimposed and sent to the speaker 7 via the outdoor cable 7a, the alarm sound derived from the main signal B for level crossing warning and the inspection sound derived from the sub-signal G for inspection, If there is a failure somewhere in the apparatus 200, it will be affected by the same effect and will also increase or decrease. Therefore, if the suitability of the check sound emitted from the speaker 7 is checked, it will be immediately emitted from the speaker 7 together with the check sound. It will be understood whether the alarm sound is appropriate.

  The check sound is detected by the sound sensing element 22 together with the alarm sound, and the sound signal generation circuit 60 obtains the sound pressure detection signal D in which the component of the frequency fk and the component of the frequency fs are mixed, and reflects it. The feedback signal E is generated by the modulation process of the frequency conversion circuit 52. At this time, the derivative component of the frequency fk is removed, and the feedback signal E is generated with the component of the frequency fo-fs which is the derivative component of the frequency fs. Since this frequency fo-fs is also high at about 35 kHz, it reaches the signal return unit 70 via the outdoor cable 7a without affecting the alarm sound emitted by the speaker 7. Moreover, the operating power of the amplifier circuit 31 and the frequency conversion circuit 52 is derived from the sub-signal G for inspection instead of the signal component of the frequency fk derived from the main signal B for crossing warning among the speaker drive current C by the power circuit 54. Since it is generated from the signal component of the frequency fs and is stable, the operating states of the amplifier circuit 31 and the frequency conversion circuit 52 are also stable, and a highly accurate feedback signal E is obtained.

  In the signal reduction unit 70, the feedback signal E of the frequency fo-fs is extracted from the superimposed signal E & C & G including the signal components of the frequency fk, the frequency fs, and the frequency fo-fs by frequency discrimination such as the bandpass filter 73, and the like. The sub-signal detection signal H having the frequency fs is generated by performing frequency conversion by the demodulation process 74. In parallel with this, the phase adjustment circuit 75 generates a synchronous detection signal from the inspection sub-signal G. Then, synchronous detection using the synchronous detection signal is performed by the synchronous detection circuit 76 to obtain an accurate signal level from the sub-signal detection signal H, and a determination circuit 77 determines a failure based on the signal level of the sub-signal detection signal H. A degree is determined.

  For this reason, when the alarm sound is emitted at an appropriate volume, the signal level of the sub-signal detection signal H falls within an appropriate range, so that it is determined that there is no failure. On the other hand, when there is almost no alarm sound, the signal level of the sub-signal detection signal H becomes almost zero, so that a silent failure determination is made. When the alarm sound is not sufficient, the signal level of the sub-signal detection signal H falls below the lower limit threshold value, so that an under-failure determination is made. Furthermore, when the warning sound is louder than an appropriate amount, the signal level of the sub-signal detection signal H exceeds the upper limit threshold value, so that it is determined that there is an excessive failure. Thus, failure detection based on the detection of the inspection sound instead of the railroad crossing warning sound is accurately performed.

[Others]
In the above embodiment, only the speaker 7 is connected. However, when the speaker 8 and other speakers are connected in addition to the speaker 7, a failure detection circuit is provided for each speaker, and each feedback signal is provided. The conversion contents of E, for example, the carrier wave frequency may be varied so as to be distinguishable.
In the second embodiment, the crossing warning main signal B and the inspection sub-signal G are generated together, but only the crossing warning main signal B is selectively generated according to the crossing condition A. However, the inspection sub-signal G may be always generated regardless of the level crossing condition A.

  Furthermore, in the second embodiment, the sound signal generation circuit 60 integrated with the inspection signal generation circuit generates and superimposes the crossing warning main signal B and the inspection sub-signal G, respectively. However, the basic waveform data of the superimposed signal of the main signal B for crossing warning and the sub signal G for inspection may be stored and reproduced. In that case, the component of the inspection sub-signal G may be extracted from the reproduced signal by a band pass filter or the like to generate a synchronous detection signal.

7, 8 ... speaker, 7a ... outdoor cable, 7b ... short cable,
10 ... Railroad crossing warning sound generator (main part), 11 ... Parallel connection part,
12 ... Drive circuit, 13 ... Output transformer, 14 ... Power amplifier,
15 ... Sound generation signal generation circuit, 16 ... Addition synthesis circuit,
17, 18 ... amplitude modulation circuit, 19a to 19c ... oscillation circuit,
21 ... Current transformer, 22 ... Sound sensing element (microphone),
23 ... amplifier circuit, 24 ... feed line, 25 ... outdoor cable,
100 ... Railroad crossing warning sound generator,
30 ... Signal return section, 31 ... Amplifier circuit,
32 ... Frequency conversion circuit, 33 ... Coupling transformer, 34 ... Power supply circuit,
40 ... Signal return unit, 41 ... Input transformer,
42 ... Amplifier circuit, 43 ... Band pass filter (BPF),
44 ... Frequency conversion circuit, 45 ... Level detection circuit, 46 ... Determination circuit,
200 ... Railroad crossing warning sound generator,
50 ... Signal return section, 52 ... Frequency conversion circuit, 54 ... Power supply circuit,
60 ... Sound generation signal generation circuit, 61 ... Sound source memory, 62 ... Reproduction circuit, 63 ... Addition synthesis circuit,
70 ... Signal reduction unit, 73 ... Band pass filter (BPF),
74: frequency conversion circuit, 75: phase adjustment circuit, 76: synchronous detection circuit, 77: determination circuit

Claims (6)

  A main body that is connected to a speaker installed toward a railroad crossing with an outdoor cable and generates a warning sound to the speaker by flowing a speaker driving current to the speaker via the outdoor cable; and A signal return unit that converts a sound pressure detection signal detected by a sound sensing element provided nearby into a feedback signal that can be distinguished from the speaker drive current and transmits the feedback signal via the outdoor cable; and A railroad crossing warning sound generator comprising a signal return unit that extracts a feedback signal from a signal transmitted through a cable and performs failure determination based on the extracted feedback signal.   The railroad crossing warning sound generator according to claim 1, further comprising a power supply circuit that receives the speaker driving current and generates operating power of the signal return unit.   The main body generates a sound signal generation circuit that generates a main signal for a level crossing alarm according to a level crossing condition, and an inspection signal generation circuit that generates a sub signal for inspection having a smaller amplitude and a higher frequency than the main signal for a level crossing alarm And a driving circuit that amplifies a superposition signal of the main signal for crossing warning and the sub signal for inspection to generate the speaker driving current, and the signal return unit includes the sound pressure detection signal. 3. The method according to claim 1, wherein the component of the sub-signal for inspection is converted while the component of the main signal for crossing warning is removed when the signal is converted into the feedback signal. Rail crossing warning sound generator.   The sound generation signal generation circuit and the inspection signal generation circuit are embodied by a circuit including a sound source memory that stores waveform data related to the main signal for crossing warning and the sub signal for inspection. The railroad crossing warning sound generator according to claim 3.   The signal return unit generates a sub-signal detection signal from the feedback signal by frequency conversion with the same frequency as the sub-signal for inspection, and signals used for failure determination are the sub-signal detection signal and the sub-signal for inspection. The crossing warning sound generating apparatus according to claim 3 or 4, wherein the alarm is generated by synchronous detection from the railway crossing.   6. The power supply circuit according to claim 3, further comprising: a power supply circuit that extracts a component of the inspection sub-signal from the speaker drive current and generates operating power of the signal return unit. Rail crossing warning sound generator.

Images