JP2010089666A - Crossing alarm sound generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To separately detect a normal state, a disconnection failure, and a short circuit failure concerning the connection to speakers. <P>SOLUTION: A crossing alarm sound generator includes: a circuit 50 generating a main signal B for a crossing alarm according to crossing conditions A; a circuit 40 generating a sub-signal F for checking having smaller amplitude and higher frequency compared with the main signal B; a circuit 12 power-amplifying both signals B, F and delivering them to speaker drive wires; a serial impedance 61 interposed in the speaker drive wire; a voltage detection part 70 generating sub-signal detection signal N from division voltage between speakers 7, 8 and the serial impedance 61; and a determination part 80 separately determining a normal state, a disconnection failure, and a short circuit failure based on the signal N. A failure in one of speakers 7, 8 can be detected with a single failure detection circuit by disposing the serial impedance 61 between the drive circuit 12 and a parallel connection part 11. Noises from a track circuit are resisted by a digital phase-shift circuit 43 and a majority selection means 83. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a railroad crossing warning sound generating device that is connected to a speaker that is attached to an alarm column beside a railroad crossing of a railway and that is connected to an obliquely downward railroad road via an outdoor cable or the like to generate a warning sound on the speaker. Specifically, the present invention relates to a technology for realizing a failure detection function for detecting an abnormal state related to connection with a speaker.

  A basic conventional railroad crossing warning sound generator 10 that does not include a failure detection function (see, for example, Non-Patent Documents 1 and 2 and FIG. 5 (a)) has two exteriors installed toward a railroad crossing road. A sound generation signal generating circuit 15 for generating a main signal B for a crossing alarm according to a binary logic level crossing condition A given from the outside in order to be connected to the attached speakers 7 and 8, and a 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 load impedance of the speakers 7 and 8 connected to the railroad crossing warning sound generator 10 as an external load is often a resistance of 16Ω, but there may be other resistance values.

  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 positive and negative with an amplitude of 20 Vp-p, for example, and a familiar alarm sound is emitted from the speakers 7 and 8 at the crossing.

The parallel connection unit 11 includes a pair of drive wires that are connected to the output side of the output transformer 13 of the drive circuit 12 (speaker drive line, speaker drive line) toward the speaker 7 and a pair of drive toward the speaker 8. Even if the speakers 7 and 8 break down, if only one of them breaks down, an alarm sound can be output to the other that has not failed.
Note that when a failure detection function is added to a railroad crossing warning sound generator, conventionally, a current transformer is attached to the drive lines of the speakers 7 and 8 to detect the speaker drive current. Then, failure detection can be performed only when the speaker is driven, that is, when an alarm sound is generated.

  Of course, some alarm sound generating devices for general use can operate the failure detection function not only when an alarm sound is generated but also when no alarm sound is generated. This is (see FIG. 5B). A frequency switching circuit 21 that oscillates at an audible frequency when the sound generation condition C is on and oscillates at a non-audible frequency when the sound generation condition C is off, and amplifies the oscillation signal. The power amplifier 22 for sending to the drive line of the speaker 23, the current transformer 24 attached to the drive line of the speaker 23 for detecting the current, and the presence or absence of the speaker drive current is determined by performing amplification and level detection on the detected signal. And a failure detection circuit 25. In this case, the generation / non-occurrence of the alarm sound is selected by switching the frequency, but since the speaker 23 is driven if there is no failure at any time, the determination result D is a failure state due to the interruption of the speaker drive current at any time. Will be shown.

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

Thus, in addition to the main signal for generating the alarm sound from the speaker, the failure detection circuit (24 + 25) which can always perform the failure detection function using the inspection sub-signal which is not recognized as the alarm sound even when the speaker is driven. Is added to the above-described conventional railroad crossing warning sound generating device 10, so that even in the railroad crossing warning sound generating device, it is possible to always determine the normal state and the failure state related to the connection with the speaker. Be expected.
However, in a railroad crossing warning sound generator, the time ratio at which no alarm sound is generated is much larger than the time ratio at which an alarm sound is output. Becomes excessive.

Moreover, in the detection method based on the presence / absence of the speaker drive current, a disconnection failure can be detected in a failure state related to the connection with the speaker, but a short-circuit failure cannot be detected. On the other hand, it is conceivable to change the detected physical quantity from current to voltage, but the detection method based on the presence or absence of the speaker drive voltage detects a short-circuit failure even if a disconnection failure can be detected among the failure states related to the speaker connection. Can not do it. For this reason, it is impossible to accurately detect the normal state related to the connection with the speaker, the disconnection failure, and the short-circuit failure only by attaching the inspection signal generation circuit and the failure detection circuit that follow the conventional technology one by one. .
Therefore, the first technical problem is to devise a method for generating and detecting the inspection sub-signal so that the normal state related to the connection with the speaker, the disconnection failure, and the short-circuit failure can be detected separately.

Further, since the railroad crossing warning sound generator 10 drives the two speakers 7 and 8 in parallel, the current transformer 24 of the failure detection circuit is connected to the drive circuit 12 of the speaker drive lines (speaker drive lines). When the speaker 11 is attached to the portion 11a between the parallel connection portion 11 and the parallel connection portion 11 (see FIG. 5 (c)), the speaker drive current flows when only one of the speakers 7 and 8 is disconnected. For this reason, in order to be able to detect the disconnection failure of the speakers 7 and 8 alone, one failure detection circuit is attached to the speaker drive line 11b extending from the parallel connection portion 11 to the speaker 7 and connected in parallel. It is necessary to attach another failure detection circuit to the speaker drive line 11c extending from the section 11 to the speaker 8, and the cost increases.
Therefore, it is a second technical problem to further devise in order to reliably detect a failure state with a single failure detection circuit even if any one of the plurality of speakers is disconnected.

Furthermore, since the railroad crossing warning sound generator is installed outdoors along with the railroad tracks, radio wave shielding is sufficient to prevent unwanted radio waves from being emitted to the surrounding environment in order to employ non-audible frequencies for the inspection sub-signal. Therefore, the cost increases. In order to avoid this, it is desirable to reduce the amplitude of the inspection sub-signal and lower the frequency of the inspection sub-signal to, for example, about 10 kHz in the boundary region between the audible frequency and the inaudible frequency.
However, the vicinity of the frequency is often used also in a train detection device that sends a train detection signal to a railway track circuit. For this reason, if the external noise from the track circuit of the railway is strong, the state detection capability related to the connection with the speaker is lowered to an undesirable level.
Therefore, it is a third technical problem to improve so that the failure state can be accurately detected without losing the noise from the track circuit even if the frequency of the sub-signal for inspection is lowered to around the audible limit.

  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 to generate a warning sound. A sounding signal generation circuit for generating a main signal for level crossing warning according to a level crossing condition, and a test signal for generating a sub-signal for inspection having a smaller amplitude and a higher frequency than the main signal for level crossing warning A generation circuit, a driving circuit that amplifies the main signal for crossing warning and the sub-signal for inspection and sends the amplified signal to the driving line of the speaker, and a passive circuit including a single impedance element or a plurality of impedance elements. Is the voltage related to the inspection sub-signal divided by the series impedance inserted in the speaker drive line in a serial connection mode and the speaker and the series impedance? A voltage detection unit that generates a sub-signal detection signal, and a determination unit that separately determines a normal state, a disconnection failure, and a short-circuit failure related to connection with the speaker based on the sub-signal detection signal. And

  Further, the railroad crossing warning sound generator of the present invention is (Solution means 2), which is the railroad crossing warning sound generator of the above-mentioned solution means 1, wherein the determination unit is in a normal state, a disconnection failure, and a short circuit with respect to the connection state of the speaker. In addition to determining failure separately, high resistance abnormality that is intermediate state between normal state and disconnection failure and low resistance abnormality that is intermediate state between normal state and short circuit failure are also determined separately It is characterized by becoming.

  Further, the railroad crossing warning sound generating device of the present invention (Solution means 3) is the railroad crossing warning sound generating device of the above-mentioned solving means 2, wherein a plurality of the speakers can be connected, and the parallel connection portion is provided inside. The series impedance is inserted in a drive line of the speaker between the drive circuit and the parallel connection portion.

  Further, the railroad crossing warning sound generator of the present invention (solution 4) is the railroad crossing warning sound generator of the above solutions 1 to 3, wherein the total impedance value is larger than the total impedance value of the series impedance and the speaker. A voltage dividing circuit (second voltage dividing circuit), which comprises a passive circuit and divides the voltage related to the test sub-signal by a ratio corresponding to the voltage division related to the test sub-signal by the speaker and the series impedance, Provided in a connection mode in parallel with the series circuit of the series impedance and the speaker, the voltage detection unit generates the sub-signal detection signal based on the difference between the two divided voltages. It is characterized by.

  The railroad crossing warning sound generator of the present invention (solution 5) is the railroad crossing warning sound generator of the above solutions 1 to 4, wherein the inspection signal generation circuit sets the phase of the inspection sub-signal to a constant period. The determination unit accumulates determination results over a period of one or more cycles of the phase shift of the inspection sub-signal, and the most numerous of them are finally determined. It is characterized by being adapted to the results.

  Further, the railroad crossing warning sound generator of the present invention (solution 6) is the railroad crossing warning sound generator of the above solutions 1 to 4, wherein the inspection signal generation circuit sets the phase of the inspection sub-signal to a constant period. The determination unit accumulates the determination results over a period of one or more rounds of the phase shift of the inspection sub-signal, and finally determines the majority of them. It is characterized by being adapted to the results.

  In such a crossing warning sound generator of the present invention (Solution 1), when connected to a speaker installed toward a railroad crossing, the sound generation signal generation circuit and the drive circuit satisfy the crossing condition. In response, an alarm sound is generated, and failure detection related to connection with the speaker is performed by a failure detection circuit having a test signal generation circuit, a series impedance, a voltage detection unit, and a determination unit. Moreover, the inspection sub-signal, which has a smaller amplitude and higher frequency than the main signal for level crossing warnings, is overlapped with the main signal for level crossing warnings, so that an increase in power consumption is suppressed, signals are easily discriminated, and failure occurs at any time. Detection is performed.

In addition, by connecting the series impedance to the speaker drive line (speaker drive line) in series with the speaker, the sub-signal detection signal corresponding to the inspection sub-signal is obtained from the divided voltage. The sub-signal detection signal becomes an analog signal instead of a binary logic, and takes different values depending on the disconnection failure and short-circuit failure related to the connection with the speaker. Since the intermediate value divided by the ratio is taken, each state related to the connection with the speaker is accurately determined by dividing the value of the sub-signal detection signal.
Therefore, according to the present invention, it is possible to separately detect the normal state related to the connection with the speaker, the disconnection failure, and the short-circuit failure, and as a result, the first technical problem is solved.

  Further, in the railroad crossing warning sound generating device of the present invention (Solution means 2), the fact that the sub-signal detection signal can be classified by being converted into an analog signal can be positively utilized, and a normal state and a disconnection failure or a short-circuit failure can be obtained. In addition, the normal state, high resistance abnormality, disconnection fault, low resistance fault, and short circuit fault related to the connection with the speaker can be detected separately. As a result, the first technical problem is highly solved.

Further, in the railroad crossing warning sound generating device of the present invention (Solution means 3), the sub-signal detection is performed by connecting the series impedance between the drive circuit and the parallel connection portion of the speaker drive line. Coupled with the fact that the signal is converted into analog signals and can be classified, the value of the sub-signal detection signal deviates from the normal state of the classification range even when the disconnection failure of any one speaker as well as the disconnection failure of any one speaker.
Therefore, according to the present invention, even if one of the plurality of speakers is disconnected, the failure state can be reliably detected by one failure detection circuit. As a result, the second technical problem is added to the first technical problem. Is also resolved.

Moreover, in the railroad crossing warning sound generator of the present invention (Solution means 4), in addition to the first voltage divider circuit comprising a series impedance and a speaker, a second voltage divider circuit having a corresponding division ratio is also provided in parallel. The sub-signal detection signal is generated based on the difference between the two divided voltages, so that the degree of failure is reflected in the amplitude of the sub-signal detection signal and the content of the failure is Whether it is the disconnection side or the short circuit side is reflected in whether the phase of the sub signal for inspection and the phase of the sub signal detection signal are in phase or inversion. For this reason, it is possible to determine whether the sub-signal detection signal is normal or faulty by checking the amplitude or level of the sub-signal detection signal, and further to the extent of the fault, and by checking the phase of the sub-signal detection signal, whether it is a disconnection fault or a short-circuit fault. Since the second voltage divider circuit has a large impedance, an undesired increase in power consumption is avoided.
Therefore, according to the present invention, the normal state related to the connection with the speaker, the disconnection failure, and the short-circuit failure can be detected in an easily understandable manner, and the first technical problem can be clearly solved.

In the railroad crossing warning sound generator of the present invention (solution 5), the phase of the inspection sub-signal is changed by a constant amount at a constant period, and the phase shift is performed over a period of one or more cycles (that is, the shift). Determination results are accumulated (for a time range in which the total amount of phases is 360 ° or more), and a final determination result is obtained by majority vote.
In an operating environment in which noise close to the frequency of the inspection sub-signal gets on the speaker drive line from a railroad track circuit or the like and disturbs the inspection sub-signal, the phase of the inspection sub-signal and the external noise Disturbance can be ignored or cannot be ignored depending on the degree of deviation, but if the ratio that can be ignored remains in more than half of the situation, introducing the above phase shift into the inspection sub-signal will result in frequent occurrence. A correct judgment and a small-frequency misjudgment are mixed.

This is because external noise from railroad track circuits, etc. that often appears as burst mode noise that continues for a long time is not easy to deal with, but is relatively easy to deal with, not burst mode noise that requires a large-scale redundant circuit. It shows that it has started to appear in a form that is close to random random noise.
For this reason, by introducing the above majority vote, erroneous determinations that occur only infrequently are ignored as final results, and only correct determination results are output as final results.
Therefore, according to the present invention, it is possible to accurately detect the failure state without losing the noise from the track circuit even if the frequency of the sub-signal for inspection is lowered to around the audible limit. In addition, the third technical problem is also solved.

In the railroad crossing warning sound generator of the present invention (solution 6), the majority decision of the solution is changed to a majority selection, so that erroneous determination is avoided even if there are a large number of discrimination categories. The reliability of the determination result is improved.
Therefore, according to the present invention, it is possible to more accurately detect the failure state without losing the noise from the track circuit even if the frequency of the sub signal for inspection is lowered to the audible limit, and as a result, the first technique In addition to the problem being solved, the third technical problem is highly resolved.

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 FIGS. 1 to 3 embodies the above-described solving means 1 to 5 (claims 1 to 5 as originally filed), and the embodiment 2 shown in FIG. Means 1 to 3 and 6 (claims 1 to 3 and 6 as originally filed) are embodied.
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. FIG. 1 is a block diagram showing a circuit structure of a railroad crossing warning sound generating device 30.

  This level crossing warning sound generating device 30 is obtained by adding a speaker failure detection function to the conventional level crossing warning sound generating device 10, and the parallel connection portion 11 and the drive circuit 12 described above are directly inherited from the level crossing warning sound generating device 10. In addition, the sound generation signal generation circuit 15 is taken over from the railroad crossing warning sound generation device 10 with some modifications, and becomes a sound generation signal generation circuit 50. Further, as a failure detection circuit embodying the present invention, Addition synthesis circuit 31, failure notification circuit 32, inspection signal generation circuit 40, series impedance 61 (first voltage dividing circuit 60), voltage dividing circuit 62 (second voltage dividing circuit), voltage detection unit 70, and determination unit 80 are added. Has been.

  The inspection signal generation circuit 40 includes a high-frequency oscillation circuit 41, a frequency division circuit 42 that divides the oscillation signal to generate a basic oscillation signal E, and a digital that generates an inspection sub-signal F from the basic oscillation signal E. And a phase shift circuit 43. The basic oscillation signal E is a rectangular wave with a duty ratio of 50%, and has a constant frequency of about 10 kHz. This frequency is orders of magnitude higher than the frequency 750 Hz of the main signal B for a railroad crossing warning, and is difficult for an ordinary person to hear. The sub-signal F for inspection takes over the duty ratio and frequency as it is from the basic oscillation signal E, but the phase is not constant, and a constant amount such as 90 ° or 72 ° with a constant period of about 0.5 second to 2 seconds. The phase is changed each time in the advance direction or in the delay direction each time. In addition, the amplitude of the inspection sub-signal F is about 0.5 Vp-p so that the sound emitted from the speakers 7 and 8 becomes almost inaudible according to the inspection sub-signal F. The amplitude of the main signal B is an order of magnitude smaller than 20 Vp-p.

  The sound signal generation circuit 50 generates the oscillation signal f1 by the frequency dividing circuit 51 in place of the oscillation circuit 19a dividing the sub signal F for inspection, and the frequency dividing circuit 52 and the open / close switch 54 in place of the oscillation circuit 19b are provided. The sub-signal F for inspection is divided and the divided signal is transmitted according to the crossing condition A to generate the oscillation signal fm. The frequency divider 53 in place of the oscillation circuit 19c divides the sub-signal F for inspection. Unlike the sound signal generation circuit 15 in that the oscillation signal f2 is generated by turning, the circuit scale is reduced. However, the main signal B for level crossing alarm is generated, and the level crossing condition In order to make a crossing warning sound when A is on, the main signal B for crossing warning is made to take an oscillation state of 750 Hz and 700 Hz alternately at a little over 2 Hz, and no crossing warning sound is made when the crossing condition A is off. Railroad crossing warning The point to take a constant value B, and the same as the sound oscillation signal generating circuit 15.

The adder / synthesizer 31 adds and synthesizes the main signal B for crossing warning and the sub signal F for inspection, thereby generating a synthesized signal H that always contains an AC component, regardless of whether the amplitude is large or small. ing.
Further, in response to the additional introduction of the addition synthesis circuit 31, the drive circuit 12 does not directly input the crossing warning main signal B but inputs the combined signal H of the addition synthesis circuit 31 so that the main crossing warning main signal B is input. The signal B and the inspection sub signal F are amplified and sent to the drive lines of the speakers 7 and 8.

  The series impedance 61 forms the first voltage dividing circuit 60 together with the speakers 7 and 8, and is connected in series with the parallel-connected speakers 7 and 8. The series impedance 61 may be composed of a passive circuit including a single impedance element as long as the series impedance 61 is inserted in a speaker connection line 11a between the drive circuit 12 and the parallel connection unit 11 in a series connection manner. It may be composed of a passive circuit including an impedance element. From the viewpoint of suppressing the power consumption of the series impedance 61, it is desirable that the impedance value of the series impedance 61 is small. However, from the viewpoint of improving the fault detection capability based on voltage division, the impedance value of the series impedance 61 is set to the speakers 7 and 8. It is desirable to increase it to the same level as the impedance value of the parallel connection circuit. In this example, assuming that the impedance of the parallel connection circuit of the speakers 7 and 8 is 16Ω, a 16Ω resistor is adopted as the series impedance 61.

  The voltage divider circuit 62 is a second voltage divider circuit provided in a connection mode in parallel with the first voltage divider circuit 60. The voltage divider circuit 60 is connected in parallel with the series impedance 61 and the speakers 7 and 8, as described above. In contrast to the series circuit with the connection circuit, the voltage dividing circuit 62 is a passive circuit having a total impedance value larger than the total impedance value of the series impedance 61 and the speaker 7 and 8 parallel connection circuit. The voltage related to the inspection sub signal F is divided at a ratio corresponding to the division of the voltage related to the inspection sub signal F by the connection circuit and the series impedance 61. For example, when the voltage dividing circuit 62 is embodied by a series circuit of a high resistance impedance 63 of 1 kΩ and a high resistance impedance 64 of XΩ, the impedance value X of the high resistance impedance 64 is 1 kΩ (resistance 63): XkΩ (resistance 64) = 16Ω (series impedance 61): From 16Ω (speakers 7 and 8), 1 kΩ is set.

  The voltage detection unit 70 generates the sub signal detection signal N from the divided voltage of the voltage dividing circuit 60, that is, from the voltage related to the inspection sub signal F divided by the series impedance 61 and the speaker 7 and 8 parallel connection circuit. However, in this embodiment, not only the divided voltage of the voltage dividing circuit 60 but also the divided voltage of the voltage dividing circuit 62 is used. That is, based on the difference between the divided voltage of the voltage dividing circuit 60 and the divided voltage of the voltage dividing circuit 62, the voltage related to the inspection sub signal F divided by the high resistance impedance 63 and the high resistance impedance 64 is also used. A detection signal N is generated.

More specifically, the voltage detection unit 70 includes a signal transformer 71, a signal amplifier 72, a pulse multiplication circuit 73, and a level detection circuit 74.
Among them, the signal transformer 71 obtains a difference voltage between the series impedance 61 and the connection voltage of the speaker 7 and 8 parallel connection circuit and the connection voltage of the high resistance impedance 63 and the high resistance impedance 64. In addition to the insulation function and phase matching function, a bandpass filter function (frequency discrimination function) that detects the voltage related to the inspection sub-signal F by separating and extracting the frequency component of the inspection sub-signal F from the main signal B for crossing warning ) Is also demonstrated.

  The signal amplifier 72 amplifies the differential voltage and generates an alternating sub-signal detection signal L that swings between positive and negative. The pulse multiplication circuit 73 generates the sub-signal detection signal L and the inspection sub-signal F. By multiplying from time to time, a half-wave sub-signal detection signal M is generated. This sub-signal detection signal M has an amplitude of zero or minute if the impedance of the parallel connection circuit of the speakers 7 and 8 is appropriate. However, when the impedance of the parallel connection circuit of the speakers 7 and 8 is out of the appropriate range, the amplitude increases according to the degree, and either the positive or negative half-wave waveform according to the increase or decrease of the impedance of the parallel connection circuit of the speakers 7 or 8. Take. Further, the level detection circuit 74 is composed of a low-pass filter embodied by, for example, an inverting amplification type integration circuit, and generates a sub-signal detection signal N of a signed level signal from a half-wave sub-signal detection signal M. ing.

  Based on the sub-signal detection signal N, the determination unit 80 determines the normal state related to the connection with the speakers 7 and 8 separately from the disconnection failure and the short-circuit failure, and in an intermediate state between the normal state and the disconnection failure. A certain high resistance abnormality and a low resistance abnormality that is an intermediate state between the normal state and the short circuit failure are also determined separately. For this purpose, the classification means 81, the storage means 82, and the selection means 83 are provided. Yes. The classifying means 81 may be embodied by a comparator or a microprocessor program. In short, if the value of the sub-signal detection signal N is “0” or in the vicinity thereof, it is determined as a normal state, and If the absolute value of the signal detection signal N is at or near the maximum value, it is determined as a disconnection failure or a short-circuit failure according to positive or negative, and if the value of the sub-signal detection signal N is between the normal state and the disconnection failure, a high resistance abnormality If the value of the sub-signal detection signal N is between the normal state and the short circuit failure, it is determined that the resistance is low. However, it is a primary determination and not a final determination.

The storage means 82 is, for example, a LIFO queue or ring buffer allocated to the memory, and takes in the primary determination results from the sorting means 81 and stores them at a fixed period. The storage means 82 stores the inspection sub-signal F by the digital phase shift circuit 43. The primary determination results are accumulated for a certain time spanning one or more phases of phase shift.
The selection means 83 is easy to be embodied by a program of the microprocessor, searches all the primary determination results held by the storage means 82 at a fixed period, and finally selects the largest number of them. The determination result P is adopted. The determination result P indicates any one of disconnection failure, high resistance abnormality, normal state, low resistance abnormality, and short circuit failure.

The failure notification circuit 32 notifies the determination result P to the outside, and is embodied by a relay in the field of railway signals. An LED failure indicator or the like is driven by the contact output of the relay.
The high resistance impedances 63 and 64 are examples of fixed resistors as shown in FIG. 1, but one or both of them may be variable resistors, or may be a resistor circuit switched by a rotary switch. In this case, since the change of the internal constant is simplified, it can be easily adapted even when the load resistance of the speakers 7 and 8 is changed from 16Ω to 8Ω or 32Ω, for example.

  The use mode and operation of the railroad crossing warning sound generator of the first embodiment will be described with reference to the drawings. FIG. 2 is an explanatory diagram of the failure detection operation of the railroad crossing warning sound generator 30. (a) is a voltage dividing circuit 62 for comparison, (b) is a voltage dividing circuit 60 on the speaker side, and (c) is normal. (D) is a signal waveform example when the speaker is short-circuited, (e) is a signal waveform example when the speaker is disconnected, (f) is a signal waveform example when the speaker is poorly connected, and (g) is when the speaker is mixed. It is an example of a signal waveform. 3A and 3C are vector diagrams of the inspection sub-signal F and the external noise, and FIGS. 3A and 3B show the case where the inspection sub-signal F is shifted by 90 degrees. (C) shows a case where the inspection sub-signal F is phase-shifted by 72 °.

  When the usage of the level crossing warning sound generator 30 and the basic level crossing warning sound generation operation are described, it can be said that this is the same as the conventional level crossing warning sound generator 10. In other words, the speakers 7 and 8 are attached to the alarm pillars beside the railroad crossing and are facing the oblique railroad crossing, but the speakers 7 and 8 and the railroad crossing alarm sound generating device 30 are connected by an outdoor cable or the like. Then, the crossing warning sound generating device 30 is ready to drive the speakers 7 and 8 in parallel, and the sound generating signal generation circuit 50 generates the main signal B for the crossing warning corresponding to the crossing condition A. B is power-amplified by the drive circuit 12, and the speakers 7 and 8 are thereby driven.

  When the level crossing condition A is turned on, a crossing warning sound is generated from the speakers 7 and 8 in which 750 Hz and 700 Hz are alternately switched over 2 Hz. When the level crossing condition A is turned off, the sound becomes quiet. Note that the inspection sub-signal F is superimposed on the crossing warning main signal B, but the inspection sub-signal F has an amplitude that is orders of magnitude smaller than that of the crossing warning main signal B. Since the frequency of F belongs to a sound range that is difficult to hear, the presence of the device inspection sub-signal F does not impair the basic function of generating a crossing warning sound not only when a crossing warning sound is generated but also when a crossing warning sound is not generated. In addition, when the output of the speakers 7 and 8 is insufficient due to the insertion of the series impedance 61 in the series connection mode, it can be easily compensated by strengthening the power amplifier 14 or boosting the output transformer 13. The insertion of 61 does not impair the function of generating a crossing warning sound.

  Next, the operation of the failure detection circuit will be described. For simplification, the phase shift and voltage detection unit by the output transformer 13 and the signal transformer 71 and the phase shift of the inspection sub-signal F and the decision of majority decision are postponed. In 70, the insensitive main signal B for level crossing warning is ignored. Specifically, the connection voltage J between the high resistance impedance 63 of 1 kΩ and the high resistance impedance 64 of 1 kΩ is directly input to the signal amplifier 72 (see FIG. 2A), and the series impedance 61 of 16Ω is obtained. The connection point voltage K of the 16Ω speaker 7 and 8 parallel connection circuit is directly used as the inverting input of the signal amplifier 72 (see FIG. 2B), and the phase of the inspection sub-signal F is fixed. This will be described with reference to the waveform portion (see FIGS. 2C to 2G).

  Then, in a normal state where the speakers 7 and 8 are 16Ω (see FIG. 2C), the connection point voltage J of the voltage division circuit 62 and the connection point voltage K of the voltage division circuit 60 are both of the test signal generation circuit 40. A rectangular wave with the same phase and half amplitude as the inspection sub-signal F, and the AC sub-signal detection signal L generated by the signal amplifier 72 from both J and K is a difference voltage between both J and K. When neglected, the value is always “0”, and the half-wave sub-signal detection signal M obtained by multiplying the sub-signal F for inspection by the pulse multiplier circuit 73 is also always “0”, and its level is detected. Since the value of the sub-signal detection signal N of the signed level signal detected by the circuit 74 is also “0”, it is determined to be in the normal state by the determination unit 80 that classifies it.

  In addition, in the short-circuit state where the resistance of the parallel connection circuit of the speakers 7 and 8 is 0Ω (see FIG. 2D), the connection point voltage J is in the form of a rectangular wave having the same phase as the sub-signal F for inspection and a half amplitude. The connection point voltage K is always “0”, and the AC sub-signal detection signal L, which is the difference voltage between the two J and K, is in the same phase as the inspection sub-signal F and has a rectangular waveform with half the amplitude. The half-wave sub-signal detection signal M obtained by multiplying the sub-signal F is also in the shape of a rectangular wave having the same phase as the inspection sub-signal F and half the amplitude, and the sub-signal detection signal N of the signed level signal whose level is detected is In this example, since the level detection circuit 74 is an inversion type, the sign becomes negative and the absolute value becomes large. Therefore, the determination unit 80 that determines the level determines that the state is a short circuit. The sign of the sub-signal detection signal N is reversed when the level detection circuit 74 is not inverted but is not inverted.

  Further, when the resistance of the parallel connection circuit of the speakers 7 and 8 becomes infinite (see FIG. 2 (e)), the connection point voltage J is in the form of a rectangular wave having the same phase as the sub-signal F for inspection and a half amplitude. The connection point voltage K has a rectangular waveform with the same phase and the same amplitude as the inspection sub-signal F, and the AC sub-signal detection signal L has a rectangular waveform with half the amplitude in the opposite phase (inverted phase) to the inspection sub-signal F. The half-wave sub-signal detection signal M is also in the shape of a rectangular wave having half the amplitude in reverse phase with the test sub-signal F, and the sign of the sub-signal detection signal N of the level signal becomes positive and the absolute value increases. It is determined as a short circuit state.

  Further, in a high resistance abnormal state where the resistance of the parallel connection circuit of the speakers 7 and 8 is increased to, for example, 32Ω due to connection failure or partial disconnection of the speakers 7 and 8 (see FIG. 2F), the connection point voltage J Is a rectangular wave having the same phase as that of the inspection sub-signal F and having a half amplitude, but the connection point voltage K is a rectangular wave having the same phase as that of the inspection sub-signal F and having a slightly larger amplitude than that of the inspection sub-signal F. Becomes a small-amplitude rectangular wave whose phase is opposite to that of the inspection sub-signal F and whose amplitude is slightly smaller than half, and the half-wave sub-signal detection signal M is also in a small-amplitude rectangular wave having a phase opposite to that of the inspection sub-signal F. Therefore, since the sub-signal detection signal N of the signed level signal becomes positive and the absolute value becomes halfway, it is determined that the resistance is high.

In addition, in a low resistance abnormality state where the resistance of the speaker 7 and 8 parallel connection circuit is reduced to, for example, 8Ω due to poor insulation or contact of the speakers 7 and 8 (see FIG. 2G), the connection point voltage J is Although the inspection sub-signal F is in the same phase as the inspection sub-signal F and has a rectangular wave shape with a half amplitude, the junction voltage K is in the same phase as the inspection sub-signal F and has a slightly smaller amplitude than the half-wave amplitude, and the AC sub-signal detection signal L is A subwave detection signal M of the same level as the inspection sub-signal F has a small amplitude and a half-wave sub-signal detection signal M also has a low-amplitude rectangular wave of the same phase as the inspection sub-signal F. Since the sign of N becomes negative and the absolute value becomes halfway, it is determined that the resistance is low.
In this way, the disconnection failure, the high resistance abnormality, the normal state, the low resistance abnormality, and the short circuit failure relating to the connection with the speakers 7 and 8 are determined at any time, and the primary determination result is obtained.

  Further, the phase shift of the inspection sub-signal F and the determination of majority decision will be described. The noise that jumps from the track circuit to the speaker connection cable, etc. is often in burst mode, and the component and frequency of the sub-signal F for inspection in the speaker drive line are the same or close to each other and the phase is reversed. This is particularly problematic because the component of the sub-signal F is canceled and the sub-signal detection is disabled (see FIG. 3 (a), the range to which the sub-signal detection cannot be detected due to noise). Even if there is such noise, the railroad crossing warning sound generator 30 can detect the component of the inspection sub-signal F and make an accurate determination.

  That is (see FIG. 3A), the phase of the inspection sub-signal F is intermittently advanced by 90 ° at a constant cycle of 0.5 seconds, for example, by the digital phase shift circuit 43. Even if the proper sub-signal detection signals L to N cannot be obtained due to noise, the proper sub-signal detection signal L is not lost at many other phases 90 °, 180 ° and 270 ° without losing noise. ˜N are obtained, and the primary determination result of the sorting means 81 for them is accumulated in the accumulating means 82 for a certain time spanning one or more phases of the phase shift of the inspection sub-signal F, and is further being accumulated by the selecting means 83. All of the primary determination results are searched at a constant cycle, and the largest number of them is adopted as the final determination result P and sent to the failure notification circuit 32.

In this case, in the primary determination result accumulated over one phase or more of the phase shift, inappropriate ones at the phase of 0 ° occupy about 1/4, and appropriate ones at the other phases are about 3/4. Therefore, the final determination result P selected by the majority decision is appropriate without the influence of noise.
Thus, the disconnection failure, the high resistance abnormality, the normal state, the low resistance abnormality, and the short circuit failure relating to the connection with the speakers 7 and 8 are determined as needed, and an appropriate determination result P is obtained.
Note that the noise is so strong that multiple phases are adversely affected, and even when the majority vote is not effective in the phase shift in units of 90 ° (see the dotted range in FIG. 3B), the phase shift in units of 72 ° The majority vote may be effective (see FIG. 3C). Generally, it is more advantageous to shift the phase by the phase unit obtained by dividing 360 ° by the odd number than by the phase shift by 360 ° by the even division unit.

About the Example 2 of the railroad crossing warning sound generator of this invention, the specific structure is demonstrated referring drawings. FIG. 4 is a block diagram of a main circuit.
This railroad crossing warning sound generator differs from that of the first embodiment described above in that the sound signal generation circuit 50 is embodied by the sound source LSI 56 (see FIG. 4A), and the decision unit 80 determines the majority. Instead of the selection means 83, a selection means 84 for selecting a majority is introduced.

  The tone generator LSI 56 generates a main signal B for a level crossing alarm corresponding to a level crossing condition A by operating with a high frequency basic oscillation signal E or its original signal as a clock, and generates a sound source from a built-in memory or an external memory. Data is read one after another to restore an audio signal and output as a main signal B for crossing warning. The sound source data can be stored in a fixed memory in advance if the standard level crossing warning sound is sufficient. If the level crossing warning sound is changed depending on the location and time, memory exchange and data rewriting functions are also added. It is good to keep.

  Similar to the selection means 83, the selection means 84 searches all the primary determination results of the storage means 82 at a constant period and outputs a determination result P. However, unlike the majority decision selection means 83, the selection means 84 stores Of the primary determination results held in the means 82, the majority determination result is adopted as the final determination result P. When there is no majority determination result, the determination impossible notification Q is issued. . As a result, when a highly accurate determination can be made, an accurate determination result is output based on the determination. On the other hand, when only a determination with a low accuracy can be performed, it is notified that the determination is impossible rather than forcing a determination result. Therefore, even if there are a large number of discrimination categories, erroneous determination is appropriately avoided, and the reliability of the determination result is improved.

It is a block diagram which shows the circuit structure of a level crossing warning sound generator about Example 1 of this invention. It is an operation explanatory diagram, (a) is a voltage dividing circuit for comparison, (b) is a voltage dividing circuit on the speaker side, (c) is a signal waveform example when normal, (d) is a signal waveform example when the speaker is short-circuited (E) is a signal waveform example when the speaker is disconnected, (f) is a signal waveform example when the speaker is poorly connected, and (g) is a signal waveform example when the speaker is mixed. (A) to (C) are vector diagrams of inspection sub-signals and external noises. When (a) and (b) phase-shift the inspection sub-signals by 90 °, (c) shows the inspection sub-signals. The case where the signal is phase-shifted by 72 ° is shown. It is a block diagram which shows the circuit structure of the principal part of a railroad crossing warning sound generator about Example 2 of this invention. (A) is a block diagram showing a circuit structure of a conventional railroad crossing warning sound generator, (b) is a block diagram showing a circuit structure of a conventional general alarm sound generator with a failure detection function, and (c) is a conventional circuit diagram. FIG. 5 is a block diagram of a main circuit in which one failure detection is added to the railroad crossing warning sound generator, and (d) is a block diagram of a main circuit in which two fault detections are added to the conventional crossing warning sound generator.

Explanation of symbols

7, 8 ... Speaker,
10 ... Railroad crossing warning sound generator,
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,
20 ... alarm sound generator,
21 ... Frequency switching circuit, 22 ... Power amplifier,
23 ... Speaker, 24 ... Current transformer, 25 ... Failure detection circuit,
30 ... Railroad crossing warning sound generator,
31 ... Addition synthesis circuit, 32 ... Failure notification circuit,
40 ... inspection signal generation circuit, 41 ... oscillation circuit,
42 ... frequency divider circuit, 43 ... digital phase shift circuit,
50: sound generation signal generation circuit, 51, 52, 53 ... frequency division circuit,
54 ... Open / close switch, 56 ... Sound source LSI,
60 ... Voltage divider circuit, 61 ... Series impedance,
62 ... voltage divider circuit, 63, 64 ... high resistance impedance,
70: Voltage detector,
71 ... Signal transformer, 72 ... Signal amplifier (Amp.),
73: Pulse multiplication circuit, 74: Level detection circuit,
80 ... determining unit, 81 ... sorting means, 82 ... accumulating means,
83 ... Selection means (majority decision), 84 ... Selection means (majority)

Claims (6)

  A sounding signal generation circuit for generating a main signal for a crossing warning according to a crossing condition in a crossing warning sound generating device connected to a speaker installed toward a railroad crossing road to generate an alarm sound, and the crossing warning A test signal generating circuit for generating a test sub-signal having a smaller amplitude and higher frequency than the main signal for driving, and driving for amplifying the main signal for crossing warning and the sub-signal for inspection and amplifying the power to the driving line of the speaker A circuit and a passive circuit including a single impedance element or a plurality of impedance elements, and a series impedance inserted in a serial connection mode in a drive line of the speaker, and the speaker and the series impedance are divided. A voltage detection unit that generates a sub-signal detection signal from a voltage related to the inspection sub-signal, and a positive connection related to the connection based on the sub-signal detection signal. State disconnection failure and a short-circuit fault and crossing warning sound generating apparatus characterized by comprising a determination unit separately.   In addition to determining the normal state, the disconnection failure, and the short-circuit failure separately with respect to the connection state of the speaker, the determination unit determines a high resistance abnormality that is an intermediate state between the normal state and the disconnection failure, and a normal state. 2. The railroad crossing warning sound generating apparatus according to claim 1, wherein a low resistance abnormality that is an intermediate state with a short circuit failure is also determined separately.   A plurality of the speakers can be connected, a parallel connection portion thereof is provided inside, and the series impedance is inserted in a drive line of the speaker between the drive circuit and the parallel connection portion. The railroad crossing warning sound generator according to claim 2, wherein   The test sub-signal is composed of a passive circuit having a total impedance value larger than the total impedance value of the series impedance and the speaker, in a ratio corresponding to the voltage division related to the test sub-signal by the speaker and the series impedance. A voltage dividing circuit that divides the voltage is provided in a connection mode that is parallel to the series circuit of the series impedance and the speaker, and the voltage detection unit is configured based on a difference between the divided voltages. The crossing warning sound generating device according to any one of claims 1 to 3, wherein a sub-signal detection signal is generated.   The inspection signal generation circuit shifts the phase of the inspection subsignal by a predetermined amount at a constant period, and the determination unit determines over a period of one or more cycles of the phase shift of the inspection subsignal. 5. A crossing warning sound generating apparatus according to claim 1, wherein the result is accumulated and the largest number among them is adopted as a final determination result. .   The inspection signal generation circuit shifts the phase of the inspection subsignal by a predetermined amount at a constant period, and the determination unit determines over a period of one or more cycles of the phase shift of the inspection subsignal. 5. A crossing warning sound generating apparatus according to claim 1, wherein results are accumulated, and a majority of them are adopted as a final determination result. .

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