JP4016975B2 - Interface circuit - Google Patents

Description

  The present invention relates to an interface circuit, and more particularly, to an interface circuit that is used in one of the first and second formats and transmits an output signal of the first circuit to the second circuit.

  Conventionally, the signal transmission format of various devices of the traffic signal system is specified in the specifications of each device. For example, a signal transmission format such as a vehicle sensor connected to a traffic signal controller is specified in the P1 type interface standard or the P2 type interface standard. The output conditions for each standard are specified in the standard document, and the signal conditions for the P1 interface standard are specified as ON (contact) when there is no signal, and OFF (disconnect) when there is a signal. The condition is specified as off (disconnected) when there is no signal, and on (contact) when there is a signal, and the rise time and fall time of the signal in each standard are defined as 100 μs or less (see, for example, Non-Patent Document 1). . The P1 type or the P2 type is determined for each prefecture, and the interface circuit such as a vehicle detector is normally configured to be usable in either the P1 type or the P2 type. In addition, specifications such as vehicle detectors stipulate that the same signal condition as when there is a signal must be set when the power is cut off.

  FIG. 4 is a circuit diagram showing the configuration of such an interface circuit. In FIG. 4, this interface circuit includes an input terminal T31, output terminals T32 and T33, a resistance element 31, a photo MOS relay 32, an N-channel MOS transistor 37, and a hard jumper 38. The photo MOS relay 32 includes photodiodes 33 and 34, a normally open photo MOS transistor 35, and a normally closed photo MOS transistor 36. The hard jumper 38 includes three terminals T34 to T36.

  Resistance element 31, photodiodes 33 and 34, and N-channel MOS transistor 37 are connected in series between a power supply potential VCC line and a ground potential GND line. The gate of N channel MOS transistor 37 receives vehicle sensing signal / D through input terminal T31. The normally open MOS transistor 35 is connected between terminals T33 and T34. The normally closed MOS transistor 36 is connected between terminals T33 and T35. The terminal T36 is connected to the output terminal T32.

  When the interface circuit is used in the P1 type, the terminals T34 and T36 of the hard jumper 38 are connected by a U-shaped pin. When the signal / D is at the “L” level of the activation level, the N-channel MOS transistor 37 becomes non-conductive, the photodiodes 33 and 34 do not emit light, and the photo MOS transistor 35 becomes non-conductive and the output terminal T32 , T33 becomes non-conductive. When the signal / D is at the “H” level of the inactivation level, the N-channel MOS transistor 37 is turned on to cause the photodiodes 33 and 34 to emit light, and the photoMOS transistor 35 is turned on to establish a connection between the output terminals T32 and T33. Conduct. When the power supply potential VCC is cut off, the photodiodes 33 and 34 do not emit light, the photo MOS transistor 35 is turned off, and the output terminals T32 and T33 are turned off.

When the interface circuit is used in the P2 type, the terminals T35 and T36 of the hard jumper 38 are connected by a U-shaped pin. When the signal / D is at the “L” level of the activation level, the N channel MOS transistor 37 becomes non-conductive and the photodiodes 33 and 34 do not emit light, and the photo MOS transistor 36 becomes conductive and the output terminals T32 and T33. Conduction between. When the signal / D is at the “H” level of the inactivation level, the N-channel MOS transistor 37 becomes conductive and the photodiodes 33 and 34 emit light, and the photoMOS transistor 36 becomes non-conductive and the output terminals T32 and T33. There is no conduction between them. When the power supply potential VCC is cut off, the photodiodes 33 and 34 do not emit light, the photo MOS transistor 36 is turned on, and the output terminals T32 and T33 are turned on. In this way, the vehicle detection signal / D is transmitted to the traffic signal controller (not shown) via the output terminals T32 and T33.
"P1 interface standard" issued by the Association of New Traffic Management Systems, June 26, 1997

  However, in the conventional interface circuit, since the response speed of the photo MOS relay 32 is generally slow, there is a possibility that the signal rise time and fall time specifications in the P1 type interface standard and the P2 type interface standard cannot be satisfied. It was.

  Therefore, a main object of the present invention is to provide an interface circuit that can be used in a desired form of the first and second forms and has a high response speed.

  The interface circuit according to the present invention is an interface circuit that is used in one of the first and second formats, and that transmits the output signal of the first circuit to the second circuit. Output terminal, photocoupler, first hard jumper, and photoMOS relay. The pair of output terminals is connected to the second circuit. When the interface circuit is used in the first format, the photocoupler emits light in response to the output signal of the first circuit being deactivated, and the interface circuit is used in the second format. In this case, the first photodiode that emits light in response to the output signal of the first circuit being activated is connected between the pair of output terminals, and the first photodiode emits light. And a phototransistor conducting. The first hard jumper is connected to the first terminal connected to one output terminal of the pair of output terminals and to the first terminal when the interface circuit is used in the second form. A second terminal. The photo MOS relay includes a photo MOS transistor connected between the second terminal and the other output terminal of the pair of output terminals, and a photo MOS transistor that emits light when a power supply voltage is applied. And a second photodiode that is turned off.

  In the interface circuit according to the present invention, since the photocoupler is used as a circuit for connecting the pair of output terminals in response to the output signal of the first circuit, the response is made as compared with the conventional case where the photoMOS relay is used. Increases speed. The first photodiode of the photocoupler emits light in response to the output signal of the first circuit being deactivated when the interface circuit is used in the first format, and the interface circuit When it is used in the second format, it emits light in response to the output signal of the first circuit being activated, so that it can be used in the desired format of the first and second formats. it can. When the second type is used, the normally closed photo MOS transistor of the photo MOS relay is connected between the pair of output terminals using the first hard jumper, so that when the power is cut off, the signal is It is possible to satisfy the requirement of the specification that the signal condition must be the same as in the case of being present.

  FIG. 1 is a circuit diagram showing a configuration of an output side interface circuit of a vehicle sensor used in a traffic signal system according to an embodiment of the present invention. In FIG. 1, this interface circuit includes an input terminal T1, output terminals T2 and T3, an inverter 1, hard jumpers 2 and 12, resistance elements 3 and 8, a photocoupler 4, an N-channel MOS transistor 7, and a photoMOS relay 9. Prepare. The hard jumper 2 includes three terminals T4 to T6. The photocoupler 4 includes a photodiode 5 and a phototransistor 6. The photo MOS relay 9 includes a photodiode 10 and a normally closed photo MOS transistor 11. The hard jumper 38 includes two terminals T7 and T8.

  The vehicle detection signal / D is input to the input terminal T1. As shown in Table 1, the signal / D becomes the “L” level of the activation level when there is a vehicle in the vehicle detection area A, which will be described later, in both the P1 type and the P2 type. When there is no vehicle in A, the deactivation level becomes “H” level.

  The input terminal T1 is directly connected to the terminal T4 and is connected to the terminal T5 via the inverter 1. Resistance element 3, photodiode 5, and N-channel MOS transistor 7 are connected in series between a power supply potential VCC line and a ground potential GND line. N channel MOS transistor 7 has its gate connected to terminal T6. The phototransistor 6 is connected between the output terminals T2 and T3.

  Resistance element 8 and photodiode 10 are connected in series between a power supply potential VCC line and a ground potential GND line. The terminal T7 is connected to the output terminal T2. The normally closed MOS transistor 11 is connected between terminals T8 and T3.

  When the interface circuit is used in the P1 type, the terminals T4 and T6 of the hard jumper 2 are connected by U-shaped pins. Signal / D is directly applied to the gate of N channel MOS transistor 7.

  When the signal / D is at the “L” level of the activation level, the N-channel MOS transistor 7 becomes non-conductive and the photodiode 5 does not emit light, and the phototransistor 6 becomes non-conductive and the output terminals T2 and T3 are not connected. Becomes non-conductive. When signal / D is at the “H” level of the inactivation level, N-channel MOS transistor 7 conducts and photodiode 5 emits light, phototransistor 6 conducts and output terminals T2 and T3 conduct.

  When the power supply potential VCC is cut off, the photodiode 5 does not emit light, the phototransistor 6 is turned off, and the output terminals T2 and T3 are turned off. When the power supply potential VCC is cut off, the photodiode 10 does not emit light and the normally closed photoMOS transistor 11 is turned on, but the terminals T7 and T8 of the hard jumper 12 are not connected, so that the output terminal It becomes non-conductive between T2 and T3.

  When the interface circuit is used in the P2 type, the terminals T5 and T6 of the hard jumper 2 are connected with U-shaped pins, and the terminals T7 and T8 of the hard jumper 12 are connected with U-shaped pins. Is done. Signal / D is inverted by inverter 1 and applied to the gate of N channel MOS transistor 7.

  When the signal / D is at the “L” level of the activation level, the N-channel MOS transistor 7 becomes conductive and the photodiode 5 emits light, the phototransistor 6 becomes conductive and the output terminals T2 and T3 become conductive. When the signal / D is at the “H” level of the inactivation level, the N-channel MOS transistor 7 becomes non-conductive and the photodiode 5 does not emit light, and the phototransistor 6 becomes non-conductive and the output terminals T2, T3. There is no conduction between them.

  When the power supply potential VCC is applied, the photodiode 10 emits light, the normally closed photo MOS transistor 11 is turned off, and the terminals T8 and T3 are turned off. When the power supply potential VCC is cut off, the photodiode 10 does not emit light, the normally closed photo MOS transistor 11 is turned on, and the output terminals T2 and T3 are turned on.

  In this embodiment, since the photocoupler 4 is used as a circuit for making the output terminals T2 and T3 conductive or nonconductive in response to the vehicle detection signal / D, the output terminal T32 in response to the vehicle detection signal / D. , T33 can be made faster or faster than the conventional case where the photo MOS relay 32 is used as a circuit for conducting or non-conducting T33.

  Further, the interface circuit can be used in a P1 form by connecting the terminals T4 and T6 of the hard jumper 2 with pins, and the interface circuit can be connected to the terminal P2 by connecting the terminals T5 and T6 of the hard jumper 2 with pins. Can be used in form. Therefore, the interface circuit can be used in a desired form of the P1 type and the P2 type.

  Further, when the interface circuit is used in the P1 type, the photodiode 5 does not emit light when the power is cut off, the output terminals T2 and T3 are nonconductive, and the terminals T7 and T8 of the hard jumper 12 are connected with pins. When the interface circuit is used in the P2 type, the photodiode 10 does not emit light when the power is cut off, and the output terminals T2 and T3 are conducted. Therefore, it is possible to satisfy the requirement of the specification that when the power is cut off, the signal condition must be the same as when there is a signal.

  FIG. 2 is a diagram showing a main part of a traffic signal system in which the interface circuit shown in FIG. 1 is used. Referring to FIG. 2, in the suburbs where the traffic volume is small, a vehicle detection area A is provided at the exit from the secondary road 20 to the main road 21, and only when the vehicle comes into the vehicle detection area A side A semi-sensitive control method is adopted in which the signal S1 is blue and the signals S2 and S3 on the main road 21 side are red. This is because it is not necessary to stop the vehicle on the main road 21 when there is no vehicle entering the main road 21 from the secondary road 20.

  A vehicle sensor 22 and a traffic signal controller 23 are provided at the intersection of the secondary road 20 and the main road 21. When there is a vehicle in the vehicle detection area A, the vehicle detector 22 sets the vehicle detection signal / D to the “L” level of the activation level, and deactivates the vehicle detection signal / D when there is no vehicle in the vehicle detection area A. To the “H” level. The interface circuit of FIG. 1 is built in the vehicle sensor 22, and the output terminals T2 and T3 are connected to the traffic signal controller 23 via signal lines. The traffic signal controller 23 detects the presence or absence of a vehicle in the vehicle sensing area A based on whether or not the output terminals T2 and T3 are conducting, and controls the signals S1 to S3 based on the detection result.

  That is, when there is no vehicle in the vehicle sensing area A, the traffic signal controller 23 turns the signal S1 on the secondary road 20 side red and the signals S2 and S3 on the main road 21 side blue to Through. The traffic signal controller 23 turns the signal S1 on the secondary road 20 side blue and the signals S2 and S3 on the main road 21 red for a predetermined time T1 when the vehicle is in the vehicle detection area A. Twenty vehicles are guided to the main road 21. After the elapse of the predetermined time T1, even when there is a vehicle in the vehicle sensing area A, the signal S1 on the secondary road 20 side is red and the signals S2 and S3 on the main road 21 side are blue for the predetermined time T2, and the main road Pass 21 cars.

  Also, as shown in Table 1, when the power of the interface circuit is interrupted for some reason, the conduction state between the output terminals T2 and T3 is the same as when the vehicle is in the vehicle sensing area A. The signal S1 on the secondary road 20 side is prevented from being fixed to red. As a case where the power supply of the interface circuit is cut off, there is a case where the power supply line is cut off or an overcurrent flows through the power supply line for some reason and a breaker connected to the power supply line cuts off the power supply.

  The state between the output terminals T2 and T3 of the interface circuit is transmitted to the traffic control center via a transmission device (not shown). When the power supply of the interface circuit is cut off, the conduction state between the output terminals T2 and T3 is the same as when the vehicle is in the vehicle sensing area A. Therefore, in the suburb where the traffic on the secondary road 20 is small, the interface circuit The traffic control center can easily detect that the power has been cut off. On the other hand, when the interface circuit is powered off, the continuity between the output terminals T2 and T3 is the same as when there is no vehicle in the vehicle sensing area A. In suburbs where there is little traffic, it is impossible to determine whether the traffic volume is low or whether the interface circuit power is cut off, and the traffic control center cannot easily detect that the interface circuit power is cut off.

  FIG. 3 is a circuit diagram showing a modification of this embodiment. Referring to FIG. 3, this interface circuit is different from the interface circuit of FIG. 1 in that inverter 1, hard jumper 2 and N-channel MOS transistor 7 are removed and input terminal T1 is directly connected to the cathode of photodiode 5. And the point that the signal / D is replaced with the signal DE.

  As shown in Table 2, when the interface circuit is used in the P1 form, the signal DE becomes high impedance (Hi-Z) when the vehicle is in the vehicle sensing area A, and the vehicle is in the vehicle sensing area A. When there is not, it becomes “L” level. Further, when the interface circuit is used in the P2 form, the signal DE becomes “L” level when the vehicle is in the vehicle detection area A, and becomes high impedance when there is no vehicle in the vehicle detection area A. That is, the vehicle detector 22 switches the level of the vehicle detection signal DE depending on whether the interface circuit is used in the P1 type or the P2 type.

  When the interface circuit is used in the P1 type, when the vehicle is in the vehicle sensing area A, the signal DE becomes high impedance, and no current flows through the photodiode 5, so the photodiode 5 does not emit light, and the phototransistor 6 Becomes non-conductive and the output terminals T2 and T3 become non-conductive. When there is no vehicle in the vehicle sensing area A, the signal DE becomes “L” level, a current flows through the photodiode 5, the photodiode 5 emits light, the phototransistor 6 is turned on, and the output terminals T2 and T3 are turned on. To do.

  Further, when the interface circuit is used in the P2 type, when the vehicle is in the vehicle sensing area A, the signal DE becomes “L” level, a current flows through the photodiode 5, the photodiode 5 emits light, and the photo The transistor 6 becomes conductive and the output terminals T2 and T3 become conductive. When there is no vehicle in the vehicle sensing area A, the signal DE becomes high impedance, and no current flows through the photodiode 5, so the photodiode 5 does not emit light, and the phototransistor 6 becomes non-conductive, and between the output terminals T2 and T3. Becomes non-conductive. Since other configurations and operations are the same as those of the interface circuit of FIG. 1, description thereof will not be repeated.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a circuit diagram which shows the structure of the interface circuit used with the traffic signal system by one embodiment of this invention. It is a figure which shows the principal part of the traffic signal system in which the interface circuit shown in FIG. 1 is used. It is a circuit diagram which shows the example of a change of this embodiment. It is a circuit diagram which shows the structure of the conventional interface circuit.

Explanation of symbols

  T1, T31 input terminal, T2, T3, T32, T33 output terminal, T4 to T8, T34 to T36 terminal, 1 inverter, 2, 12, 38 hard jumper, 3, 8, 31 resistance element, 4 photocoupler, 5, 10, 33, 34 Photodiode, 6 Phototransistor, 7, 37 N-channel MOS transistor, 9, 32 PhotoMOS relay, 11, 36 Normally closed photoMOS transistor, 20 Secondary road, 21 Main road, 22 Vehicle detector, 23 traffic signal controller, A vehicle sensing area, S1-S3 signal, 35 normally open photo MOS transistor.

Claims (4)

An interface circuit that is used in one of the first and second formats and that transmits the output signal of the first circuit to the second circuit,
A pair of output terminals connected to the second circuit;
When the interface circuit is used in the first format, light is emitted in response to the output signal of the first circuit being deactivated, and the interface circuit is used in the second format. When the output signal of the first circuit is activated, the first photodiode that emits light in response to the activated state is connected between the pair of output terminals, and the first photodiode emits light. A photocoupler including a phototransistor that conducts in response to
A first terminal connected to one output terminal of the pair of output terminals, and a second terminal connected to the first terminal when the interface circuit is used in the second format. A first hard jumper including a terminal, a photo MOS transistor connected between the second terminal and the other output terminal of the pair of output terminals, and a power supply voltage is applied An interface circuit comprising a photo MOS relay including a second photodiode that emits light to the non-conductive state of the photo MOS transistor. The activated state and deactivated state of the output signal of the first circuit are the first potential and the second potential, respectively.
When the interface circuit is used in the first format, the output signal of the first circuit is passed as it is, and when the interface circuit is used in the second format, the output of the first circuit is passed. A gate circuit for inverting and passing a signal; and a switching element for emitting light by applying the power supply voltage to the first photodiode in response to the output signal of the gate circuit being set to the second potential. The interface circuit according to claim 1. The gate circuit is
An inverter that outputs an inverted signal of the output signal of the first circuit; a third terminal that receives the output signal of the first circuit; a fourth terminal that receives the output signal of the inverter; and the interface circuit A fifth terminal connected to the third terminal when used in the first form, and a fifth terminal connected to the fourth terminal when the interface circuit is used in the second form; Including a second hard jumper containing,
The interface circuit according to claim 2, wherein an output signal of the gate circuit is output from the fifth terminal. The anode of the first photodiode receives a power supply potential, the cathode of the first photodiode receives an output signal of the first circuit,
When the interface circuit is used in the first form, the activation state and the deactivation state of the output signal of the first circuit are a high impedance state and a ground potential, respectively.
2. When the interface circuit is used in the second form, the activated state and the deactivated state of the output signal of the first circuit are the ground potential and the high impedance state, respectively. Interface circuit.

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