CN1979570B - Tax-controlled cashier - Google Patents

Abstract

The invention relates to a tax-controlled cash register, comprising power supply, master control module, keyboard module, display module, data storage module, real-time clock module, user card module, tax-control card module, printing module, and communication interface module, where the printing module comprises a monostable circuit which drives printing head to output needles in metastable state and withdraws the printing needles in stable state. Because of adopting the specially designed monostable triggering circuit to automatically control the needle outputting time of the printing head, it can assure the printing needles can be withdrawn in the safe time in various abnormal states so as to put an end to happening of accidents of burning printing head. It adopts self-recovery fuse to protect the user card power supply circuit, so as to assure the user card seat can not influence normal operations of the other modules in system when meeting with various physical attacks. And it adds special anti-interference devices in the data storage module so as to improve data storage reliability and besides, improve the operating reliability of the whole machine.

Description

Tax control cash register

technical field

The invention relates to cash collection equipment, more specifically to a tax-controlled cash collection machine.

Background technique

Tax-controlled cash registers are used in shops, hotels and other industries to collect money. In addition to providing collection services for merchants, the service function of the tax-controlled cash register can also perform tax calculation management for the tax department, that is, there are two service objects, and they are mutual. Can record, display and print the product name and amount of each transaction; can clear, immediately correct, outdated correction, return, discount, price increase, price reduction processing for the product; can handle cash, checks, credit cards, coupons, etc. Transaction settlement method; non-operating expenses and income can be processed. When the printing head of the tax-controlled cash register prints out the needle, it must retract the printing needle within a certain period of time. If the printing needle cannot be retracted in time due to various reasons, the printing head will be burned due to the excessive current of the driving coil of the printing needle. The output and retraction of the printing needles of the tax-controlled cash registers in the prior art are generally directly controlled by the microprocessor. If the microprocessor crashes when the printing needles are ejected, the printing needles cannot be retracted, which will cause the print head to be burned. . When a third party performs various physical attacks on the user card seat (such as inserting an iron sheet), the power supply current of the user card will suddenly increase, and the user card or the interface circuit of the user card will be burned. The machine has no protection for this. When the tax control cash register works normally, it will generate a large amount of tax control data and store it in the data memory inside the machine. In the process of data storage, the data memory will be affected by various interference signals from the power supply, which reduces the reliability of data storage.

Contents of the invention

The technical problem to be solved by the present invention is to provide a high-reliability tax-controlled cash register for the above-mentioned defects of the prior art.

The technical solution adopted by the present invention to solve the technical problem is: to construct a tax control cash register, including a power supply module, a main control module, a keyboard module, a display module, a data storage module, a real-time clock module, a user card module, a tax control Card module, printing module, communication interface module. It is characterized in that the printing module includes a monostable circuit that drives the print head to output needles in a temporary stable state, retracts the printing needles in a stable state, and is connected to the monostable circuit for triggering the monostable circuit to enter a temporary stable state. And automatically control the monostable trigger circuit of the printing head needle output time, the monostable circuit includes a monostable trigger chip 74HC123, a timing capacitor connected to the RCext pin and Cext pin of the chip 74HC123, a timing resistor, and one end and power supply The other end of the voltage connection is respectively connected to the current limiting resistors of the B pin and the CLR pin.

In the tax-controlled cash register according to the present invention, the printing module also includes connecting with the monostable circuit, driving the print head to output needles in a temporary stable state in the monostable circuit, and driving the needle output in a stable state in the monostable circuit. A print drive circuit that retracts the print pin in a state, and a print data latch connected to the print drive circuit for latching printing dot matrix data, wherein the print data latch is connected to the print control circuit, the The trigger circuit is connected with the print control circuit, and the print drive circuit is connected with the print head.

In the tax-controlled cash register of the present invention, the user card interface module includes a user card power supply pin, and also includes a triode for controlling the user card power supply pin switch, and the emitter of the triode is connected to the power supply pin of the user card. The power supply module is connected, the base of the triode is connected with the control module to control the power supply of the power supply pin, and a power supply pin is connected between the collector of the triode and the user card power supply pin The fuse used to protect the user card is automatically disconnected when the current is too large.

In the tax-controlled cash register of the present invention, the fuse is a self-recovery fuse that can automatically recover after the current is normal after being disconnected.

In the tax control cash register of the present invention, the triode is a PNP triode.

In the tax-controlled cash register of the present invention, the power supply module supplies power to the data storage module through a filter.

In the tax control cash register of the present invention, the filter is an EMI filter.

The beneficial effect of the present invention is that, since the tax control cash register of the present invention adopts a specially designed monostable trigger circuit to automatically control the needle-out time of the print head, it can ensure that the machine is in various abnormal states, The printing needle can be retracted within the specified safety time, preventing the accident of burning the printing head. Since the tax-controlled cash register of the present invention uses a self-recovery fuse to protect the power supply circuit of the user card, when a third party performs various physical attacks on the user card seat, the power supply current of the user card will suddenly increase, and when the current exceeds the designed When the value is set, the fuse will be automatically disconnected to ensure that the normal operation of other modules of the system will not be affected; when the physical attack is removed, the fuse will be restored, and the operation of the user card can return to normal. Since the tax-controlled cash register of the present invention adds a special anti-interference device to the power port of the data memory during the process of storing data, it can greatly suppress the interference factors generated by the power system and improve the reliability of data storage. At the same time, the reliability of the whole machine is also improved.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and embodiment, in the accompanying drawing:

Fig. 1 is a structural block diagram of an embodiment of the tax control cash register of the present invention;

Fig. 2 is the structural block diagram of the print module of the tax control cash register of the present invention;

Fig. 3 is the circuit diagram of the monostable circuit in the tax control cash register of the present invention;

Fig. 4 is a circuit diagram of an embodiment of the tax control cash register of the present invention.

Detailed ways

As shown in FIG. 1 , it is a structural block diagram of an embodiment of the tax control cash register of the present invention. In this embodiment, the tax control cash register includes a power supply module, a main control module, a keyboard module, a display module, a data storage module, a real-time clock module, a user card module, a tax control card module, a printing module, and a communication interface module. The main control module is connected with the keyboard module, display module, data storage module, real-time clock module, user card module, tax control card module, printing module and communication interface module to control their work.

As shown in Figure 2, it is a structural block diagram of the printing module of the tax control cash register of the present invention, including a trigger circuit connected to the monostable circuit for triggering the monostable circuit to enter a transient state, and the monostable circuit The monostable circuit is connected to the monostable circuit to drive the print head out of the needle in a temporary state, and the monostable circuit is a printing driver circuit to retract the printing needle in a steady state, and the monostable circuit is used to latch the printing dot A print data latch for array data; the print data latch is connected to the print control circuit, the trigger circuit is connected to the print control circuit, and the print drive circuit is connected to the print head.

In the present invention, a specially designed monostable trigger circuit is used to automatically control the needle-out time of the printing head, which can ensure that the printing needle can be retracted within the specified safe time after the printing head is out of the needle under various abnormal conditions. , put an end to the accident of burning the print head. When printing the invoice, the microcontroller first drives the stepper motor to complete the paper feeding and positioning of the invoice, and then latches the dot matrix data of the printed characters, and then triggers the monostable circuit to enter the temporary Steady state, in this state, the output signal of the monostable circuit outputs the latched printing dot matrix data to the printing needle drive circuit, driving the print head to print out the needle; when the monostable circuit exits the temporary stable state, it returns to the steady state , the output signal of the monostable circuit will prohibit the printing dot matrix data from being output to the printing needle drive circuit, so that the print head will close the needle and end printing. The circuit diagram of the monostable circuit is shown in Figure 3, and the chip U8B and peripheral devices are single Stable circuit (simple explanation).

As shown in FIG. 4 , it is a circuit diagram of an embodiment of the tax control cash register of the present invention. Among them, U1 is a single-chip microcomputer, U2 is an address latch, U3 is a RAM memory, U3 is an EPROM memory, U20 and U21 are motor drivers, J4 and J5 are printer interfaces, and PP1-PP8 pins latch dot matrix data to be printed. Chip U8B and peripheral devices are monostable circuits.

In one embodiment of the tax-controlled cash register of the present invention, the user card interface module is also provided with a triode for controlling the power supply pin switch of the user card, wherein the emitter of the pole tube is connected with the power module, The base of the triode is connected with the control module to control whether the power of the power supply pin is available, and a device is connected between the collector of the triode and the power supply pin of the user card to automatically disconnect when the current is too large. the fuse of the user card mentioned above. The fuse among them is a self-recovery fuse that can automatically recover after the current is normal after being disconnected. The transistor is a PNP transistor. With such a setting, when a third party conducts various physical attacks on the user card socket, the power supply current of the user card will suddenly increase. When the current exceeds the design value, the fuse will be automatically disconnected to ensure that it does not affect the other modules of the system. Normal work; when the physical attack is removed, the fuse will be restored, and the operation of the user card can return to normal.

In one embodiment of the tax-controlled cash register of the present invention, the power supply module supplies power to the data storage module through a filter. The filter is an EMI filter. In this embodiment, by adding a special anti-interference device to the power port of the data storage, the interference factors generated by the power system can be greatly suppressed, the reliability of data storage is improved, and the reliability of the whole machine is also improved.

Claims (3)

1. A tax-controlled cash register, comprising a power module for providing power, a keyboard module, a display module, a data storage module, a real-time clock module, a user card module, a tax-controlled card module, a printing module, a communication interface module, and The keyboard module, the display module, the data storage module, the real-time clock module, the user card module, the tax control card module, the printing module, and the main control module that are connected to each other and control their work, are characterized in that the printing module includes A monostable circuit that drives the print head to eject needles in a temporary stable state, retracts the printing needles in a steady state, and is connected to the monostable circuit for triggering the monostable circuit to enter a temporary stable state and automatically controlling the time for the print head to eject needles A monostable trigger circuit, the monostable circuit includes a monostable trigger chip 74HC123, a timing capacitor connected to the RCext pin and the Cext pin of the chip 74HC123, a timing resistor, and one end connected to the power supply voltage and the other end connected to the B pin, respectively. Current limiting resistor connected to CLR pin. 2. The tax control cash register according to claim 1, characterized in that, the printing module also includes being connected to the monostable circuit in which the monostable circuit is temporarily stable to drive the print head out of the needle and The monostable circuit is a printing drive circuit that retracts the printing needle in a stable state, and a print data latch connected to the print drive circuit for latching the printing dot matrix data, and the printing module also includes a lock with the printing data The print control circuit is connected to the memory, the trigger circuit is connected to the print control circuit, and the print drive circuit is connected to the print head. 3. The tax-controlled cash register according to claim 1, wherein the user card module includes a user card power supply pin, and also includes a triode for controlling the user card power supply pin switch, the The emitter of the triode is connected with the power supply module, the base of the triode is connected with the main control module to control whether the power of the power supply pin is available, the collector of the triode is connected with the power supply tube of the user card A fuse for protecting the user card that is automatically disconnected when the current is too large is connected between the pins.

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