JP4050580B2 - Photocoupler circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photocoupler circuit for high-speed transmission used in a sensor repeater connected to a line drawn from a receiver.
[0002]
[Prior art]
Conventionally, in a disaster prevention monitoring system that collects and monitors disaster prevention information by a terminal call by address designation between a receiver and a terminal known as R type, a relay for a plurality of sensors as terminals on a line drawn from the receiver Connected. A plurality of sensor lines are drawn from this sensor repeater, and an on / off type fire sensor is connected.
[0003]
The receiver designates the address of the sensor repeater, transmits a call signal, collects the detection information of the fire detector from the sensor repeater that has determined the address match, and monitors the fire.
[0004]
In the sensor repeater, a photocoupler circuit as shown in FIG. 7 is provided in order to electrically isolate the transmission line on the receiver side from the sensor line.
[0005]
In the photocoupler circuit of FIG. 7, the light emitting side circuit connects the LED 100a of the photocoupler 100 to the output of the light emitting drive element G1 via the resistor R10 via the line of the power supply voltage V1. The light receiving side circuit connects the phototransistor 100 phototransistor (hereinafter referred to as “PT”) 100b from the power supply voltage V2 line via the resistor R11, and the resistor R11 and PT100b are connected to the light receiving drive element G2 by input connection. is doing.
[0006]
The operation of this photocoupler circuit is such that when a transmission pulse signal that becomes H level is input to the light emitting drive element G1 and the output becomes L level, a current flows through the LED 100a and light is emitted. The input of the light receiving drive element G2 is pulled to L level, and an H level light receiving signal is output.
[0007]
[Patent Document 1]
JP 59-10315 A
[Patent Document 2]
Japanese Utility Model Publication No. 3-17899
[Patent Document 3]
Japanese Utility Model Publication No. 62-53796
[Patent Document 4]
Japanese Patent Laid-Open No. 6-274783
[0008]
[Problems to be solved by the invention]
By the way, in the disaster prevention monitoring system, many detector repeaters such as several hundreds are connected to the transmission path from the receiver, and the photocouplers are driven all at once by receiving the calling signal from the receiver. Therefore, a photocoupler circuit used for the sensor repeater is required to have a low current consumption.
[0009]
Therefore, if the resistors R10 and R11 are increased in the photocoupler circuit of FIG. 7 in order to reduce the current consumption, the current flowing through the LED 100a decreases, the amount of light emission decreases, and the response time until the light receiving side PT 100b is turned on is delayed. . Further, when the resistances R10 and R11 are reduced, the response time is increased, but the current consumption is increased.
[0010]
An object of the present invention is to provide a photocoupler circuit that reduces current consumption and at the same time has a high response speed.
[0011]
[Means for Solving the Problems]
In order to achieve this object, the photocoupler circuit of the present invention includes a light emitting drive element, two sets of photocouplers, and a light receiving drive element, and the LEDs of the two sets of photocouplers are connected in series to the anode side at one end. Each of the cathode side of the other end is connected to the output of the light emitting drive element, and a low resistance and a capacitor are connected in series between the midpoint between the LED connections and the ground to constitute a light emitting side circuit, and two sets Connect the phototransistor of the photocoupler in series, connect the collector side of one end to the power supply, connect the emitter side of the other end to ground, and connect the midpoint between the phototransistor connections to the input of the light receiving drive element. Thus, a light receiving side circuit is configured.
[0012]
According to the photocoupler circuit of the present invention, when the output of the light emitting drive element becomes H level, the charging current flows to the capacitor via the LED of the photocoupler and the low resistance, and the LED emits light due to the low resistance. Sufficient charging current flows initially, so that the phototransistor of the light receiving side circuit switches at high speed. Here, the time constant of the low resistance and the capacitor is set to a time longer than the phototransistor on the light receiving side can be switched, but the average current consumption is very small because it is a short time.
[0013]
Subsequently, when the output L of the light emitting side driving element becomes L, a sufficient discharge current flows from the charged capacitor via another LED with a low resistance, so that another phototransistor on the light receiving side can be switched at high speed. There is no current consumption from.
[0014]
As a result, the consumption current of one cycle in which the output of the light emitting drive element changes from the H level to the L level is an average consumption current obtained by averaging the charging current during the H level period, and this average consumption current can be sufficiently reduced. .
[0015]
Furthermore, the photocoupler circuit of the present invention is such that a medium resistor is connected in parallel with a capacitor provided on the light emitting side circuit and a low resistance series circuit, and a phototransistor connection between the light receiving side circuit is pulled down via a high resistance. Features.
[0016]
As a result, even if the H level output of the light emitting side driving element continues for a long time and the charging current of the capacitor does not flow, the current that maintains the light emission of the LED continuously flows through the intermediate resistor, so that the phototransistor on the light receiving side Remains on. In this case, a small amount of current determined by the medium resistance continues to flow. However, since the current is sufficiently lower than the current due to the low resistance, the current consumption can be reduced accordingly.
[0017]
When the L level output of the light emitting drive element continues for a long time, the discharge of the capacitor is completed, the LED is turned off, the two phototransistors on the light receiving side are turned off, and the input of the light receiving drive element is in a floating state. Although it may become indefinite, by pulling down here with a high resistance, it is possible to fix and stabilize the input state as it should be.
[0018]
In another form of the photocoupler circuit according to the present invention, a light emitting drive element, two sets of photocouplers, and a light receiving drive element are provided, and two sets of photocoupler LEDs are connected in series via two low resistances. The anode side at one end and the cathode side at the other end are connected to the output of the light emitting drive element, and a capacitor is connected between the midpoint between the two low resistance connections and the ground to constitute a light emitting side circuit. The phototransistors of two sets of photocouplers are connected in series, the collector side of one end is connected to the power supply, the emitter side of the other end is connected to the ground, and the midpoint between the phototransistor connections is the input of the light receiving drive element It is characterized in that a light receiving side circuit is configured by being connected to.
[0019]
Thus, when the discharge current and the suction current of the light emitting drive element are different, or when the threshold value of the light receiving drive element is not the midpoint voltage, the two low-resistance values are changed to The light emission characteristics can be adjusted to stabilize the operation.
[0020]
In this case as well, a low resistance on the plus side in the light emitting side circuit, a capacitor and a series resistor are connected in parallel with the series circuit, and a high resistance is connected between the plus side phototransistor on the light receiving side circuit and the low resistance. Pull down via.
[0021]
Furthermore, the present invention inserts and connects a low resistance between the two sets of phototransistors and the input of the light receiving drive element.
[0022]
Thereby, it is possible to prevent the light receiving drive element from malfunctioning due to the through current flowing to the ground side through the two sets of phototransistors.
[0023]
In the photocoupler circuit of the present invention, the middle resistance is at least about 10 times the resistance value with respect to the low resistance, and the high resistance is at least about 10 times the resistance value with respect to the middle resistance. . For example, low resistance has a relationship of several kilo ohms, medium resistance has several tens of kilo ohms, and high resistance has several hundreds of kilo ohms.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an explanatory diagram of a disaster prevention monitoring system provided with a sensor repeater in which the photocoupler circuit of the present invention is used. In FIG. 1, the disaster prevention monitoring system of the present invention includes a power line V, a transmission line S, a transmission common line SC, a telephone line T and a common line as a line 2 from a receiver 1 installed in a manager's room to a warning area. Line C is drawn. Here, the common line C is a common line for the power line V and the telephone line T.
[0025]
A plurality of sensor repeaters 3 are installed on the line 2 drawn from the receiver 1. In the disaster prevention monitoring system of the present invention, the receiver 1 receives a response information by transmitting a command such as a call by designating a terminal address set in the sensor repeater 3, and Can connect as many detector repeaters 3 as the number of terminal addresses that can be set, and in a large-scale disaster prevention monitoring system, hundreds of detector repeaters 3 are connected to the receiver 1. .
[0026]
A plurality of sensor lines L1 to Ln and a sensor common line LC are drawn out from the sensor repeater 3, and an on / off type fire detection is performed between the sensor line L1 and the sensor common line LC. A device 4 is connected.
[0027]
In this example, the case where one fire detector 4 is connected to each of the detector lines L1 to Ln is taken as an example, but a plurality of fire detectors 4 are provided for each detector line as necessary. Connected. Moreover, although the terminator for a disconnection detection is connected to the termination | terminus of the sensor lines L1-Ln, this is abbreviate | omitted.
[0028]
On the other hand, in the alert area where the sensor repeater 3 is installed, a telephone jack 5 is provided in order to make a call communication between the receiver 1 and the site. Specifically, the telephone jack 5 is provided in a fire transmitter or the like installed in the alert area.
[0029]
A telephone line T drawn from the receiver 1 is connected to one end of the telephone jack 5, and the other end of the telephone jack 5 is connected to a sensor common line LC drawn from the sensor repeater 3 by a telephone common line TC. The common line C drawn from the receiver 1 is connected to the common line LC.
[0030]
The receiver 1 is provided with a monitoring control unit 7, a transmission circuit unit 8, an operation display unit 9, a telephone circuit unit 10, and a telephone jack 11. A telephone 12 is inserted and connected to the telephone jack when making a call.
[0031]
On the other hand, the sensor repeater 3 is provided with a transmission circuit unit 13, a CPU circuit unit 14, and a fire reception circuit unit 15. In the sensor repeater 3, two sets of the photocoupler circuit 18 of the present invention are provided and electrically separated for the exchange of the downstream signal and upstream signal between the transmission circuit unit 13 and the CPU circuit unit 14. Yes. The photocoupler circuit 18 includes two sets of photocouplers 16 and 17.
[0032]
The power supply to the transmission circuit unit 13 is performed by the transmission line S and the transmission common line SC. For this reason, between the transmission line S and the transmission common line C, the downstream signal from the transmission circuit unit 8 and the upstream signal from the transmission circuit unit 13 are superimposed simultaneously with the power supply voltage.
[0033]
Here, the downstream signal from the transmission circuit unit 8 of the receiver 1 is superimposed as a voltage signal between the transmission line S that also serves as a power supply line and the transmission common line SC. The upstream signal from the transmission circuit unit 13 of the sensor repeater 3 to the receiver 1 is transmitted by changing the line current flowing between the transmission line S and the transmission common line SC.
[0034]
In the normal monitoring state, the transmission circuit unit 8 of the receiver 1 transmits a call signal including a call command in which the terminal addresses of the sensor repeater 3 are sequentially specified. This call signal is transmitted to the sensor relay. The signal is received by the transmission circuit unit 13 of the device 3 and input to the CPU circuit unit 14 via one photocoupler circuit 18.
[0035]
The CPU circuit unit 14 extracts the call address from the received call signal, compares it with a preset self address, and when it determines that the address matches, the status signal in the sensor repeater 3 at that time is used as the other photo. The signal is output to the transmission circuit unit 13 via the coupler circuit 18 and sent to the receiver 1 as a change in line current from the transmission circuit unit 13.
[0036]
As a response signal of the sensor repeater 3 with respect to the calling signal from the receiver 1, for example, corresponding to a specific bit in 8-bit response data, a detection state such as normal, failure, fire, etc. is set and handled. A response signal is returned to the receiver by setting the status bit.
[0037]
When a fire is detected, a fire interrupt signal is sent to the receiver 1 to cause the receiver 1 to perform a fire interrupt process. That is, when the receiver 1 receives the fire interrupt signal from the sensor repeater 3, the receiver 1 detects the fire by executing an address search process for searching for the address of the sensor repeater 3 that detects the fire. The sensor repeater 3 is specified, and a call signal is continuously sent to the sensor repeater 3 of the specified address to obtain a response of fire detection information.
[0038]
Further, in the transmission circuit unit 8 of the receiver 1, in parallel with the transfer of the calling signal to the sensor repeater 3, the disconnection detection control signal is transmitted at a constant cycle, for example, at intervals of 1 second. Upon receiving the signal, the CPU circuit unit 14 causes the fire receiving circuit unit 15 to perform a disconnection detection operation between the sensor lines L1 to Ln and the sensor common line LC. The detection result by the disconnection detection operation is sent back as a response signal to the next calling signal after the disconnection detection process is completed.
[0039]
The monitoring control unit 7 of the receiver 1 performs a fire reception process, a failure generation process, and the like based on information on the sensor relay 3 obtained by transmission control with the sensor relay 3 by the transmission circuit unit 8. Perform supervisory control. An operation display unit 9 is provided for the monitoring control unit 7, and in addition to a fire display and a failure display, an operation input necessary for each display is performed.
[0040]
Further, when the telephone 6 is inserted and connected to the telephone jack 5 on the terminal side as shown in the figure, the telephone circuit unit 10 detects the current flowing between the telephone line T and the common line C at this time and recognizes the telephone connection. Then, the supervisory control unit 7 is notified of the telephone set insertion connection, and a call calling operation is performed.
[0041]
If there is a telephone call, the manager can take a call with the telephone 6 on the terminal side by taking out the telephone 12 installed in the receiver 1 and connecting it to the telephone jack 11. .
[0042]
FIG. 2 is a circuit diagram showing a basic embodiment of a photocoupler circuit according to the present invention. In FIG. 2, the photocoupler circuit of the present invention comprises a light emitting side circuit 20 and a light receiving side circuit 21, and two sets of photocouplers 16 and 17 are provided to electrically separate and couple them. The photocoupler 16 includes LEDs 16a and 17a serving as light emitting units and phototransistors (hereinafter referred to as “PT”) 16b and 17b serving as light receiving units.
[0043]
The light-emitting side circuit 20 connects the LEDs 16a and 17a of the photocouplers 16 and 17 in series, connects one end on the anode side of the LED 16a to the output of the light-emitting drive element G1, and the other end on the cathode side of the LED 17a in the same manner. It is connected to the output of the light emitting drive element G1.
[0044]
Further, a low resistance R0 and a capacitor C1 are connected between the midpoint between the connections of the LEDs 16a and 17a and the ground. The light emission side circuit 20 is provided on the transmission circuit unit 13 side of the sensor repeater 3 of FIG. 1, and the power supply voltage V1 supplied between the transmission line S and the transmission common line SC from the receiver 1 is supplied. Receive and operate.
[0045]
The light receiving side circuit 21 connects the PTs 16b and 17b of the photocouplers 16 and 17 in series between the power supply line of the power supply voltage V2 and the ground, and connects the midpoint between the connections of PT16b and 17b to the input of the light receiving drive element G2. ing.
[0046]
Here, the light emitting drive element G1 is an inverting input type, which inverts an L level input of a received signal from the transmission line side to an H level output, and inverts an H level input to output an L level. The light receiving drive element G2 is an output inversion type, which inverts an L level input to an H level output and inverts an H level input to an L level output. Further, as the resistance value of the low resistance R0 provided in the light emitting side circuit unit 20, for example, a resistance value of several kilohms is used.
[0047]
Next, the operation of the photocoupler circuit of FIG. 2 will be described. FIG. 3A shows a circuit operation when the output of the light emitting drive element G1 changes from L level to H level in the photocoupler circuit of FIG.
[0048]
In FIG. 3A, when the output of the light emitting drive element G1 becomes H level in response to the L level input signal, for example, an H level voltage corresponding to the power supply voltage V1 is output, and the LED 16a of the photocoupler 16 and the low resistance A current i1 flows through a path passing through R0 and the capacitor C1. This current i1 is a charging current depending on the time constant of the low resistance R0 and the capacitor C1, and a sufficiently large current i1 flows immediately after the light emitting drive element G1 rises to the H level, and then gradually with the charging of the capacitor C1. In addition, the current i1 decreases.
[0049]
Here, by setting the time constant of the resistor R0 and the capacitor C1 to a time longer than the time at which the PT 16b of the light receiving side circuit 21 can be switched, the light emitting drive element G1 is at the H level over the input L level period of the transmission pulse signal. During this time, the LED 16a emits light sufficiently, and the PT 16b can be switched on.
[0050]
When PT16b is turned on by the light emission of the LED 16a, the current i2 flows from the power supply line of the power supply voltage V2 through the PT16b to the light receiving drive element G2, and the input of the light receiving drive element G2 becomes H level. L level.
[0051]
Subsequently, if the input of the light emitting drive element G1 changes to H level, the output of the light emitting drive element G1 becomes L level as shown in FIG. Therefore, in the light emission side circuit 20, the output voltage of the light emitting drive element G1 passes through the low resistance R0 and the LED 17a of the photocoupler 17 by the charging voltage of the capacitor C1 charged in the state of FIG. A discharge current i3 flows.
[0052]
The LED 17a emits light by the discharge current i3, and the PT 17b on the light receiving side circuit 21 side is turned on. Therefore, the current i4 flows through the PT 17b that is turned on from the input of the light receiving drive element G2, and the input of the light receiving drive element G2 becomes L level, which is inverted and the output becomes H level.
[0053]
Here, looking at the current consumption on the light emission side circuit 20 side that is supplied with power from the receiver, the charging current i1 that flows to the capacitor C1 when the light emission drive element G1 in FIG. Is the consumption current, and the L level period of the output of the light emitting drive element G1 in FIG. 3B is the consumption of the discharge current i3 due to the charging voltage of the capacitor C1, so that the power There is no current consumption.
[0054]
Therefore, an average current consumption obtained by averaging the charging current i1 flows during the period of one transmission pulse signal input to the light emitting drive element G1, and therefore the average current consumption can be sufficiently reduced.
[0055]
Further, since the switching of the photocouplers 16 and 17 is performed by the light emission of the LEDs 16a and 17a by the charging current of the capacitor C1 and the discharging current of the capacitor C1, the charging current and the discharging current sufficiently flow in the initial state, so that PT16b, High-speed switching of 17b can be realized.
[0056]
FIG. 4 is a circuit diagram of another embodiment of the photocoupler circuit according to the present invention in which a middle resistance and a high resistance for stabilization are added to the photocoupler circuit of FIG.
[0057]
In the photocoupler circuit of FIG. 4, first, a medium resistance R1 is connected in parallel with a series circuit of a low resistance R0 and a capacitor C1 connected between the midpoint between the connection of the LEDs 16a and 17a in the light emitting side circuit 20 and the ground. Further, a high resistance R4 is connected between the midpoint between the connections of PT16b and 17b and ground with respect to the light receiving side circuit 21, and the midpoint between these connections is pulled down.
[0058]
Here, the resistance value of the middle resistor R1 provided in the light emitting side circuit 20 has a value of at least 10 times the low resistance R0. For example, if the low resistance R0 is several kilo ohms, the middle resistance R1 is several tens of kilo ohms. The resistance value of the high resistance R4 provided in the light receiving side circuit 21 is at least about 10 times the value of the medium resistance R1. For example, if the medium resistance R1 is several tens of kilohms, the high resistance R4 is several hundred kiloohms. It becomes.
[0059]
The intermediate resistor R1 provided in the light emission side circuit 20 avoids the unstable operation of the photocoupler circuit when the H level output of the light emitting drive element G1 continues for a long time. That is, when the H level of the output of the light emitting drive element G1 continues for a long time, in the embodiment of FIG. 2, the charging current i1 for the capacitor C1 as shown in FIG. 3A decreases with time. Eventually, it becomes 0, so that the LED 16a is turned off and the PT 16b is turned off.
[0060]
Therefore, by providing the middle resistor R1, in addition to the charging current of the capacitor C1, a current is passed through the middle resistor R1 in parallel. The LED 16a is allowed to flow to maintain light emission, whereby the on state of the PT 16b can be maintained.
[0061]
When the middle resistor R1 is provided in this way, the current consumption increases by the amount of current flowing through the middle resistor R1, but it is about 10 minutes compared to the case where the LED 16a emits light with the current flowing through the conventional low resistance. The current consumption can be reduced to about 1.
[0062]
On the other hand, the high resistance R4 provided in the light receiving side circuit 21 eliminates an unstable operation state when the L level output of the light emitting drive element G1 continues for a long time. In the embodiment of FIG. 2, when the output of the light emitting drive element G1 becomes L level as shown in FIG. 3B, the LED 17a of the photocoupler 17 emits light due to the discharge current of the capacitor C1. When the L level output of the drive element G1 continues for a long time, the discharge of the capacitor C1 is completed, the LED 17a is turned off, and the PT 17b is also turned off.
[0063]
At this time, the input to the light receiving drive element G2 of the light receiving side circuit 21 is in a floating state with respect to the ground side because the PTs 16b and 17b are both off, and the operation becomes unstable.
[0064]
Therefore, in the embodiment of FIG. 4, since the pull-down connection for connecting the input of the light receiving drive element G2 to the ground via the high resistance R4 is performed, the discharge current of the capacitor C1 becomes 0, and the LED 17a Even if the PT 17b is turned off by turning off the light, the input level of the light receiving drive element G2 is fixed to the L level by pull-down by the high resistance R4, and can operate stably.
[0065]
FIG. 5 shows another embodiment of the photocoupler circuit according to the present invention. In this embodiment, low-resistance R2 and R3 are connected in series between the LEDs 16a and 17a for the light-emitting side circuit 20, and the low-resistance R2 is connected. , R3, the capacitor C1 is connected to the ground from the midpoint between the connections. For the light receiving side circuit 21, low resistances R5 and R6 are connected in series between PTs 16b and 17b, and the midpoint between these connections is connected to the input of the light receiving drive element G2.
[0066]
In this embodiment, the embodiment shown in FIG. 2 shares the low resistance R0 as the charging resistance and discharging resistance for the capacitor C1, and is separated into a low resistance R2 for charging and a low resistance R3 for discharging. The light receiving side circuit 21 also uses separate low resistances R5 and R6 for current flow into the input when PT16b is turned on and current flow from the input when PT17b is turned on.
[0067]
As described above, the light-emitting side circuit 20 and the light-receiving side circuit 21 are each provided with two resistance values for the midpoint, thereby facilitating balance adjustment with respect to the midpoint potential.
[0068]
That is, when the discharge current and the suction current of the light emitting drive element G1 are different, or when the threshold value of the light receiving drive element G2 is not the midpoint voltage, the light emission characteristics of the two sets of photocouplers 16 and 17 are to be adjusted. There is a case. In this case, the operation can be stabilized by adjusting the values of the two low resistances R2 and R3.
[0069]
Further, in the light receiving side circuit 21 of FIG. 2, during operation, a current may pass from the power supply voltage V2 to the ground side via the PTs 16b and 17b (through current), and the operation of the light receiving drive element G2 may become unstable. There is sex. Therefore, by inserting low resistances R5 and R6 between the input ends of PT16b and PT17b and the light receiving drive element G2, it is possible to prevent a through current. Further, a small resistor having a small wattage can be used.
[0070]
The operation in the embodiment of FIG. 5 is basically the same as the operation shown in FIG. 3 in the embodiment of FIG.
[0071]
That is, when the output of the light emitting drive element G1 becomes H level, a charging current flows through the path through the LED 16a, the low resistance R2, and the capacitor C1, the PT 16b is turned on by the light emission of the LED 16a, and the light receiving drive through the low resistance R5. A current flows through the input of the element G2, the input becomes H level, and the output becomes L level inverted.
[0072]
Next, when the output of the light emitting drive element G1 becomes L level, a charging current flows through the low resistance R3 and the LED 17a due to the charging voltage of the capacitor C1, the PT 17b is turned on by the light emission of the LED 17a, and the light receiving drive through the resistor R6. A current flows out from the input of the element G2, and at this time, the input is pulled to the L level to become the H level output.
[0073]
FIG. 6 is a circuit diagram of an embodiment in which a medium resistance and a high resistance for stabilizing the operation are added to the embodiment of FIG. In FIG. 6, a middle resistor R <b> 1 is added to the light emission side circuit 20. The middle resistance R1 is connected to the ground from the middle point between the LED 17a and the low resistance R2. That is, the middle resistor R1 is connected in parallel to the series circuit of the low resistor R2 and the capacitor C1. The high resistance R4 of the light receiving side circuit 21 has a midpoint between the connection of PT16b and the low resistance R5 connected to the ground by pulling down.
[0074]
The intermediate resistor R1 in the light emission side circuit 20 continues to emit light from the LED 16a with the current flowing through the intermediate resistor R1 even after the charging current to the capacitor C1 is cut off when the H level output of the light emitting drive element G1 continues for a long time. Let Further, when the L level output of the light emitting drive element G1 continues for a long time, even if the LED 17a is turned off and the PT 17b is turned off when the charging of the capacitor C1 is completed, the input of the light receiving drive element G2 is pulled down by the high resistance R4. Is fixed at the L level to eliminate the instability of the floating state.
[0075]
In the above embodiment, the photocoupler circuit used for the exchange of transmission signals in the sensor repeater of the disaster prevention monitoring system is taken as an example. However, the present invention is not limited to this, and electrical separation is performed. The present invention can be applied as it is to a circuit that performs the above, particularly a circuit that exchanges high-speed pulse signals. Further, the present invention includes appropriate modifications that do not impair the object and advantages thereof, and is not limited by the numerical values shown in the above embodiments.
[0076]
Further, the circuit combination of the light emission side circuit 20 and the light reception side circuit 21 in FIGS. 2, 4, 5, and 6 is not limited to the combination of the embodiments, and for example, the light emission side circuit 20 in FIG. 2 and the light reception side in FIG. A combination of the circuits 21 and a combination of the light emitting side circuit 20 in FIG. 6 and the light receiving side circuit 21 in FIG. 4 are also conceivable.
[0077]
【The invention's effect】
As described above, according to the present invention, the photocoupler that operates with the H level output of the light emitting drive element and the photocoupler that operates with the L level output of the light emitting drive element are provided separately, and the H of the light emitting drive element is provided. At the time of level output, one photocoupler is driven by the charging current of the capacitor, and at the L level output of the light emitting drive element, another photocoupler is driven to emit light by the discharge current of the capacitor. The necessary current consumption is only the charging current in the H level section of the light emitting drive element, and there is no current consumption from the outside for driving the photocoupler by the discharge current at which the output of the light emitting drive element becomes L level. The viewed current consumption becomes an average current during the period of H level and L level of the light emitting drive element, and can be made sufficiently small.
[0078]
In addition, since the photocoupler is driven by the charge current and discharge current of the capacitor, a sufficiently large current is obtained for both the rise of the discharge current and the rise of the charge current, thereby realizing high-speed switching of the photocoupler. can do.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a disaster prevention monitoring system in which a photocoupler circuit of the present invention is used.
FIG. 2 is a circuit diagram of a basic embodiment of the present invention.
FIG. 3 is an operation explanatory diagram in the embodiment of FIG. 2;
4 is a circuit diagram of another embodiment of the present invention by adding a middle resistance and a high resistance for stabilization to FIG.
FIG. 5 is a circuit diagram of another embodiment of the present invention.
6 is a circuit diagram of another embodiment of the present invention by adding a middle resistance and a high resistance for stabilization to FIG.
FIG. 7 is a circuit diagram of a conventional photocoupler.
[Explanation of symbols]
1: Receiver
2: Track
3: Repeater for sensor
4: Fire detector
5, 11: Telephone jack
6,12: Telephone
7: Monitoring control unit
8, 13: Transmission circuit section
9: Operation display section
10: Telephone circuit
14: CPU circuit section
15: Fire receiving circuit section
16, 17: Photocoupler
16a, 17a: LED
16b, 17b: Phototransistor
18: Photocoupler circuit
19: Transmitter circuit
20: Light emission side circuit
21: Light receiving side circuit

Claims (6)

Equipped with a light emitting drive element, two sets of photocouplers and a light receiving drive element,
The LEDs of the two sets of photocouplers are connected in series, and the anode side at one end and the cathode side at the other end are connected to the output of the driving element for light emission. A resistor and a capacitor are connected in series to configure the light-emitting side circuit,
The phototransistors of the two sets of photocouplers are connected in series, the collector side of one end is connected to the power source, the emitter side of the other end is connected to the ground, and the midpoint between the phototransistor connections is connected to the light receiving drive element. A photocoupler circuit comprising a light receiving side circuit connected to an input. 2. The photocoupler circuit according to claim 1, wherein a medium resistor is connected in parallel with the capacitor and a low-resistance series circuit provided in the light-emitting side circuit, and the phototransistor connection between the light-receiving side circuit is connected through a high resistance. A photocoupler circuit characterized by pull-down connection. Equipped with a light emitting drive element, two sets of photocouplers and a light receiving drive element,
The two sets of photocoupler LEDs are connected in series via two low resistances, one end of the anode side and the other end of the cathode side are connected to the output of the light emitting drive element, and the two low resistances Connect the capacitor between the midpoint between the connections and the ground to configure the light emission side circuit,
The phototransistors of the two sets of photocouplers are connected in series, the collector side of one end is connected to the power source, the emitter side of the other end is connected to the ground, and the midpoint between the phototransistor connections is connected to the light receiving drive element. A photocoupler circuit comprising a light receiving side circuit connected to an input. 4. The photocoupler circuit according to claim 3, wherein an intermediate resistor is connected in parallel with a series circuit of the plus side low resistance provided in the light emitting side circuit and the capacitor, and a high resistance is provided between the phototransistor connections of the light receiving side circuit. A photocoupler circuit characterized by being connected via pull-down. 5. The photocoupler circuit according to claim 1, wherein a low resistance is inserted between each of the two sets of phototransistors and the input of the light receiving drive element. circuit. 6. The photocoupler circuit according to claim 1, wherein the intermediate resistance is at least about 10 times the resistance of the low resistance, and the high resistance is at least about 10 times the intermediate resistance. A photocoupler circuit characterized by having a resistance value of.

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