JPH06203260A - Automatic vending machine - Google Patents

Abstract

PURPOSE:To accurately detect a fault of a semiconductor switching element which powers ON and OFF a load. CONSTITUTION:An electromagnetic solenoid 1 for bend mechanism driving is powered ON and OFF by a phototriac 3 which is turned ON with the vending command signal Sa from a controller 8. The fault detecting circuit 10 consisting of the series circuit of a two-way Zener diode 11 for constant voltage loading, a resistor 12 for current limitation, and light emission diodes 13a and 13b consisting the primary side of a photocoupler 14 is connected to the phototriac 3 in parallel. The fault detecting circuit 10 outputs an OFF signal Soff by the current interruption corresponding to the turning-ON operation of the phototriac 3 and outputs an ON signal Son by current supply corresponding to its turning- OFF operation. The controller 8 judges abnormality of the phototriac 3 on the basis of the output of the fault detecting circuit 10 each time the vending command signal Sa is outputted to the phototriac 3 and stopped from being outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vending machine in which a semiconductor switching element is used to connect and disconnect a load, and more particularly to a vending machine in which a failure of the semiconductor switching element is self-determined. .

[0002]

2. Description of the Related Art Conventionally, in an automatic vending machine which sells products in response to the insertion of money and the operation of a product selection switch, a load such as a bend mechanism is generally provided. It has been practiced to form a power supply path for a relay switch by a relay switch.
However, in the configuration using such a relay, there is a problem that the operation reliability is inferior due to the presence of the mechanical contact mechanism and the component cost is relatively high. It is considered that the electric path is formed by a semiconductor switching element.

[0003]

In the case of adopting a configuration in which the semiconductor switching element is used to cut off the load,
In order to solve the problem of so-called product liability, it is necessary to have a configuration capable of accurately detecting the failure of the semiconductor switching element. However, conventionally, there is no failure detection circuit capable of accurately performing such detection, and this is an unsolved problem.

The present invention has been made in view of the above circumstances, and an object of the present invention is to accurately detect a failure of a semiconductor switching element although the semiconductor switching element is used to connect and disconnect a load. It is to provide a vending machine that can do this.

[0005]

In order to achieve the above-mentioned object, the present invention provides a vending machine having a structure in which an energization path for a load is formed by a semiconductor switching element turned on by a command signal from a control means. In parallel with the switching element, after connecting a failure detection circuit consisting of a voltage limiting element that bears a constant voltage, a current limiting element and a series circuit of the primary side light emitting element of the photocoupler, the control means, the output state of the command signal A fault detection signal is generated when an ON signal is output from the secondary side switching element of the photocoupler, and when an OFF signal is output from the secondary side switching element of the photocoupler in the output stop state of the command signal. It is configured to do.

[0006]

When the semiconductor switching element is turned on, no voltage is applied to the failure detection circuit connected in parallel with the semiconductor switching element. Therefore, the primary side light emitting element of the photocoupler is not energized and lit, and the photocoupler is not turned on. No ON signal is output from the secondary side switching element. In addition, when the semiconductor switching element is turned off, a voltage is applied to the failure detection circuit, so that the primary side light emitting element of the photocoupler is turned on and the secondary switching element of the photocoupler is turned off. No signal is output.

Therefore, when an ON signal is output from the secondary side switching element of the photocoupler in the state where the control means outputs an instruction signal to turn it on to the semiconductor switching element, and the output of the instruction signal is stopped. If the off signal is output from the secondary switching element of the photocoupler in the above state, it means that some abnormality has occurred in the semiconductor switching element or the transmission path of the command signal. The means will generate a fault detection signal. In this case, since the failure detection circuit is provided with a voltage limiting element that bears a constant voltage, it becomes difficult for noise current to flow to the failure detection circuit, and as a result, the failure detection operation as described above is tolerated. Noise characteristics are improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows the configuration of a sales operation circuit in a vending machine. In FIG. 1, a plurality of electromagnetic solenoids 1 as a load are provided to drive a well-known bend mechanism group provided in the main body of the vending machine, and the product selling operation is performed according to the energization. It has become. However, for convenience of explanation,
Only one electromagnetic solenoid 1 is shown, and this electromagnetic solenoid 1 is connected to a commercial AC power supply 2 via a phototriac 3 as a semiconductor switching element.

The phototriac 3 includes a light emitting diode 4
The light-emitting diode 4 is also connected in the forward direction between the positive power supply terminal + Vcc and the ground terminal via the current limiting resistor 6 and the npn-type transistor 7. The transistor 7
Is configured to be turned on through the base bias circuit 9 by a sales command signal Sa from an output terminal P of a controller 8 (corresponding to a control means in the present invention) described later, which is the center of the vending machine.

The phototriac 3 is provided in parallel with this,
The resistor 3a having a relatively large resistance value is connected, and the failure detection circuit 10 is also connected. This failure detection circuit 10
Is a bidirectional Zener diode 1 as a voltage limiting element.
1. A resistor 12 as a current limiting element and light emitting diodes 13a and 13b connected in antiparallel to each other are connected in series.

The resistance values of the resistor 3a and the resistor 12 in the failure detection circuit 10 are set so that the current flowing through the electromagnetic solenoid 1 through the resistor 3a or 12 is sufficiently higher than its operating level when the phototriac 3 is off. It is set to a small value. Further, the voltage (zener voltage) borne by the bidirectional Zener diode 11 in the failure detection circuit 10 becomes a predetermined value smaller than the voltage level applied to both ends of the failure detection circuit 10 with the phototriac 3 turned off. It is set.

The light emitting diodes 13a and 13b constitute a primary side light emitting element of the photocoupler 14, and the photocoupler 14 is provided with a phototransistor 15 as a secondary side switching element. The phototransistor 15 has a collector connected to the positive power supply terminal + Vcc and an emitter connected to a pull-down resistor 16
And a capacitor 17 are connected in parallel to the ground terminal. Further, the emitter of the phototransistor 15 is connected to the input terminal Q of the controller 8 via the buffer amplifier 18. Therefore, when the phototransistor 15 is turned on, the ON signal Son composed of a high level signal is given to the input terminal Q of the controller 8, and when the phototransistor 15 is turned off, the input terminal Q of the controller 8 is set to low level. An off signal Soff composed of a signal is given.

The controller 8 is configured to include an MPU, and when the product is sold in response to the insertion of money and the operation of the product selection switch, the output terminal P is used.
Outputs a sales command signal Sa to turn on the transistor 7. Thus, when the transistor 7 is turned on, the light emitting diode 4 of the photocoupler 5 is
Since the photo triac 3 is turned on according to the lighting of,
The electromagnetic solenoid 1 is energized to perform a product selling operation.

FIG. 2 shows the contents of the failure judgment routine in the control program of the controller 8, which will be described below along with the related operations. That is, in this failure determination routine, the output state of the sales command signal Sa is determined (step A1), and if it is being output, it is determined whether or not the off signal Soff is input to the input terminal Q (step A2). .

In this case, when the phototriac 3 is normally turned on in response to the output of the sales command signal Sa, no current flows in the failure detection circuit 10, so the phototransistor 15 in the photocoupler 14 is turned on. Therefore, the off signal Soff is given to the input terminal Q of the controller 8. Therefore, the state determined to be "YES" in step A2 corresponds to the state in which the phototriac 3 is operating normally, and in such a state, the return is performed to execute the normal sales control operation. To do.

On the other hand, when the phototriac 3 is not turned on in spite of the output of the sales command signal Sa, a voltage larger than the sharing voltage of the bidirectional Zener diode 11 is applied to both ends of the failure detection circuit 10. In this state, a current (current equal to or lower than the operation level of the electromagnetic solenoid 1) flows through the failure detection circuit 10, so that the light emitting diodes 13a and 13b are turned on and the phototransistor 15 is turned on, and the input of the controller 8 is turned on. For terminal Q,
The ON signal Son is provided instead of the OFF signal Soff. Therefore, the state determined to be "NO" in step A2 corresponds to a state in which the phototriac 3 is not normally turned on, or a failure has occurred. In such a state, the abnormality processing step A3 is executed. Return after executing. In the abnormality processing step A3, a failure detection signal is generated, and an abnormal state is notified based on the failure detection signal.

On the other hand, when it is judged "NO" in the step A1, that is, when the output of the sales command signal Sa is stopped, the ON signal Son to the input terminal Q is outputted.
It is determined whether or not the input has been made (step A4).

In this case, when the phototriac 3 is normally turned off in response to the stop of the output of the sales command signal Sa, a current flows through the failure detection circuit 10 and the photocoupler 1
Since the phototransistor 15 in 4 is turned on, the off signal Son is given to the input terminal Q of the controller 8. Therefore, the state determined as “YES” in step A4 corresponds to the state in which the phototriac 3 is operating normally, and in such a state, the normal sales control operation is performed. To return.

On the other hand, when the phototriac 3 is turned on even when the output of the sales command signal Sa is stopped, no current flows in the failure detection circuit 10, so that the phototransistor in the photocoupler 14 is not supplied. 15 does not turn on, and the input terminal Q of the controller 8 is
The off signal Soff is supplied instead of the on signal Son. Therefore, the state determined to be "NO" in step A4 corresponds to a state in which a failure has occurred such as the phototriac 3 not being normally turned off. In such a state, a failure detection signal is generated. Then, after executing the abnormality processing step A5 for notifying the abnormal state, the process returns.

In summary, according to the present embodiment described above, the failure detection circuit 10 outputs the off signal Soff by shutting off the current in response to the turning on of the phototriac 3, and also supplies the current depending on the turning off. The ON signal Son is output, and the controller 8 outputs the operation command and the operation stop command to the phototriac 3 for driving the electromagnetic solenoid 1 by the output from the failure detection circuit 10 as described above each time. No. 3 abnormality is self-determined, and therefore, it becomes possible to accurately detect the failure of the phototriac 3. In this case, since the failure detection circuit 10 is provided with the bidirectional Zener diode 11 that bears a constant voltage, it becomes difficult for a noise current to flow to the failure detection circuit 10, and as a result, the phototriac 3 fails. The noise resistance of the detection operation is improved, and the detection can be performed more accurately.

[0021]

As is apparent from the above description, according to the present invention, a failure is provided which includes a photocoupler which is operated only in parallel with a semiconductor switching element when a voltage higher than the burden voltage of the voltage limiting element is applied. With the detection circuit provided, when the photocoupler is operated in the output state of the command signal for turning on the semiconductor switching element,
Also, since the failure detection signal is generated when the operation of the photocoupler is stopped while the output of the command signal is stopped, the failure of the semiconductor switching element occurs even though the load switching is performed by the semiconductor switching element. This has an excellent effect that the detection can be performed accurately.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a main part showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a main part of control contents.

[Explanation of symbols]

In the drawings, 1 is an electromagnetic solenoid (load), 3 is a phototriac (semiconductor switching element), 8 is a controller (control means), 10 is a failure detection circuit, 11 is a bidirectional Zener diode (voltage limiting element), and 12 is a resistor. (Current limiting element), 13a and 13b are light emitting diodes (primary side light emitting elements), 14 is a photocoupler, and 15 is a phototransistor (secondary side switching element).

Claims (1)

[Claims] 1. A vending machine having a structure in which an energization path for a load is formed by a semiconductor switching element that is turned on by a command signal from a control means, wherein a voltage limiting element that bears a constant voltage in parallel with the semiconductor switching element, When a failure detection circuit composed of a series circuit of a current limiting element and a primary side light emitting element of the photocoupler is connected, the control means outputs an ON signal from the secondary side switching element of the photocoupler in the output state of the command signal. Also, the vending machine is configured to generate a failure detection signal when an off signal is output from the secondary side switching element of the photocoupler while the output of the command signal is stopped.