JPH0342494Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a vending control device for a vending machine.

2. Description of the Related Art A vending control section of a vending machine, which executes a product dispensing operation by reading the operation of a product selection switch using a microcomputer, is configured as shown in FIG.

A CPU chip 1 of a microcomputer is operated with a driving power supply voltage of 5 volts applied between a power supply terminal 2 and a reference potential 3. When the product selection switch 3 is operated by a user of the vending machine, the contacts are set to the closed state, and the second CPU chip 1 is connected between terminal 6 and reference potential 3 shown in the figure.
Apply an auxiliary voltage of 24 volts higher than 5 volts of the supply voltage of , and connect a resistor 5 between terminal 6 and reference potential 3.
A series circuit of a resistor 5 and a product selection switch 7 is connected, and a connection point P between the resistor 5 and the product selection switch 7 is connected to an input port IN of the CPU chip 1 via a level shifter 4.

When the product selection switch 7 is operated, the input of the level shifter 4 is reversed from 24 volts to 0 volts,
The output of the level shifter 4 seen from the side of the CPU chip 1 is inverted from the "L" level to the "H" level.
The CPU chip 1 determines that the product selection switch 7 has been operated from this inverted state of the input port IN, and
Executing sales processing.

In order to prevent the CPU chip 1 from malfunctioning when the 5-volt drive power supply voltage rises, the reset terminal RST of the CPU chip 1 is kept at "H" until the 5-volt drive power supply voltage rises reliably.
Generally, the configuration is such that the reset terminal RST is maintained at the "L" level after the drive power supply voltage of 5 volts is stabilized, and the input from the input port IN is accepted.

Problem to be solved by the invention: In the interior of a vending machine, the auxiliary voltage of 24
Since the voltage power line drives the power source of the product dispensing device and is also connected to and used as a power source for many other loads, the quality of the power source is often poor.

A particular problem is when a short circuit occurs in the 24-volt auxiliary voltage system. Specifically, there is a high frequency of accidents in which the coil of one of the motors used as the power source for the product dispensing device shoots out, and if a motor coil shoot accident occurs and the auxiliary voltage goes down, the actual Even though the product selection switch 7 was not operated,
The potential of the input of the level shifter 4 decreases, and the state of the output of the level shifter 4 is inverted to "H" level,
There is a problem in that the CPU chip 1 reads that the product selection switch 7 has been operated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a vending control device that can prevent erroneous readings by a microcomputer even when the auxiliary voltage is down.

Means for Solving the Problems The vending machine sales control device of the present invention is a vending machine in which a microcomputer reads the operation of a product selection switch and executes a product dispensing operation, and the input is the driving power supply voltage of the microcomputer. a first level shifter whose output is connected to an input port of the microcomputer, and whose output state is inverted when the input potential drops to the first potential; A product selection switch is interposed between the input of the level shifter and the reference potential, the input is pulled up to the auxiliary voltage, the output is connected to the reset terminal of the microcomputer, and the input potential is lower than the first potential. The present invention is characterized in that it includes a second level shifter whose output state is inverted when the potential decreases to a high second potential.

Effect: According to this configuration, the second level shifter, which inverts its level earlier than the first level shifter when the auxiliary voltage decreases, prohibits the microcomputer from reading the output state of the first level shifter.

Embodiment Hereinafter, an embodiment of the present invention will be described based on FIG. Components having the same functions as those in FIG. 2 showing the conventional example will be described with the same reference numerals.

FIG. 1 shows a vending control device for a vending machine according to the present invention, which differs from the conventional device shown in FIG. 2 in that a second level shifter 8 is added.

The input of the second level shifter 8 is connected to the auxiliary voltage 24 volts through a resistor 9, and the output of the second level shifter 8 is connected to the reset terminal of the CPU chip 1.
Connected to RST.

If the potential of the input of the first level shifter 4 when the output of the first level shifter 4 is inverted from the "L" level to the "H" level is the first voltage, then the second level shifter 8 receives the auxiliary voltage of 24 volts. When the voltage drops to the second voltage, which is higher than the first voltage, the output is reversed and the reset terminal of CPU chip 1 is activated.
RST goes to "H" level and CPU chip 1 is reset.

Therefore, even if a short circuit occurs in the 24-volt auxiliary voltage system, CPU chip 1 will not incorrectly read that "product selection switch 7 has been operated," and reliability will be maintained. improves.

Effects of the invention As described above, according to the invention, the input is pulled up to an auxiliary voltage higher than the driving power supply voltage of the microcomputer, and the output is connected to the microcomputer by the second level shifter connected to the reset terminal of the microcomputer. The first level shifter connected between the input port of the microcomputer and the product selection switch has a second potential higher than the first potential to be inverted. Since it is set to the potential, when the auxiliary voltage decreases, the first
By outputting the second level shifter earlier than the level shifter, it is possible to reliably prohibit the microcomputer from reading the output state of the first level shifter, improving the reliability of the vending control device of the vending machine. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of a vending machine sales control device of the present invention, and FIG. 2 is a block diagram of a conventional vending machine vending control device. 1...CPU chip, 2...CPU chip power supply terminal, 4...First level shifter, 6...Auxiliary voltage terminal, 7...Product selection switch, 8...Second level shifter.

Claims (1)

[Scope of utility model registration request] In a vending machine in which a microcomputer reads the operation of a product selection switch and executes a product dispensing operation, the input is raised to an auxiliary voltage higher than the drive power supply voltage of the microcomputer, and the output is raised to an auxiliary voltage that is higher than the drive power supply voltage of the microcomputer. a first level shifter connected to the port and whose output state is inverted when the input potential drops to the first potential; a product selection switch interposed between the input of the first level shifter and a reference potential; a second level shifter whose input is pulled up to said auxiliary voltage, whose output is connected to a reset terminal of said microcomputer, and whose output state is reversed when the input potential drops to a second potential higher than the first potential; A vending control device for a vending machine, wherein the second level shifter prohibits a microcomputer from reading the output state of the first level shifter when the auxiliary voltage decreases.