JP5494113B2 - Current control circuit and printer - Google Patents

Description

  The present invention relates to a current control circuit, a printer, and a current control method.

  2. Description of the Related Art A POS system capable of managing POS (Point Of Sale) instead of a conventional register is known as an apparatus for inputting sales at a store or the like and issuing deposits / withdrawals or receipts (see, for example, Patent Document 1). The POS system includes a POS terminal, a printer, a counter, a cash drawer, and the like. Among these, the cash drawer for taking in and out money is connected to, for example, a POS terminal or a POS printer, and the opening / closing operation of the drawer tray is controlled by the current supplied from either of them.

  In cash drawers, the impedance of a drive circuit responsible for opening and closing operations in a drawer tray is often determined for each model depending on its internal configuration. On the other hand, when constructing a POS system, a cash drawer connected to a printer may be selected without considering the impedance. In such a case, a non-standard overcurrent flows through the cash drawer, resulting in a failure of the current supply circuit on the printer side due to the overcurrent.

  Therefore, in the past, by providing an overcurrent protection element such as a fuse in the current supply circuit in the printer, even when connected to a non-standard cash drawer, the current supply circuit may fail due to the overcurrent as described above. Preventive methods are adopted.

JP 2000-172950 A

  In a conventional current supply circuit, when an overcurrent protection element is activated (such as a broken fuse), a printer incorporating the current supply circuit stops operating. However, users of the system such as a cashier clerk do not know what caused the operation to stop, and have to call a repair person or service person to elucidate and check the cause of the operation stop of the printer. Then, there is a problem that the printer cannot be used during inspection and repair (such as fuse replacement) of the printer.

  In order to solve the above problems, the present invention provides a current control circuit for controlling a current supplied to a cash drawer, wherein the current detection detects whether or not the current has reached a predetermined threshold value. And a current control unit that controls the current to be equal to or less than the threshold value by chopping in response to the current reaching the threshold value. .

  By providing such a current control circuit in the cash drawer supply side device, the circuit can be protected from overcurrent without stopping the supply of current to the cash drawer.

  Further, in the current control circuit, the current control unit is configured to receive the current and to switch the supply and stop of the current based on whether the current has reached the threshold value; and The magnitude of the current that is provided on the input side of the chopper circuit section and input to the chopper circuit section is detected, and the magnitude of the current has reached a predetermined protection reference value, It is preferable that the chopper circuit unit includes a protection circuit that stops the input of the current.

  Thereby, a current that cannot be controlled by the current control circuit, for example, an inrush current, can be detected to protect the current control unit.

  According to another aspect of the present invention, there is provided a printer connected to a cash drawer, a printing unit that prints on printing paper based on given print data, and a current supply that supplies current to the cash drawer And a current control circuit that controls the supply of the current, the current control circuit detecting whether the current has reached a predetermined threshold, and the current is the A printer comprising: a current control unit configured to control the current to be equal to or less than the threshold value by chopping in response to reaching the threshold value.

  According to another aspect of the present invention, there is provided a current control method for controlling a current supplied to a cash drawer, wherein whether or not the current has reached a predetermined threshold value is detected, A current control method is provided, wherein the current is controlled to be equal to or less than the threshold value by chopping in response to reaching the threshold value.

1 is a perspective view showing an external appearance of a POS system 10 according to an embodiment of the present invention. 2 is a functional block diagram showing internal configurations and connection relationships of a printer 100 and a cash drawer 400 in the POS system 10. FIG. It is a figure which shows an example of the structure of the lock mechanism. 3 is a diagram illustrating an example of a circuit configuration of an unlocking current supply unit 130. FIG. 6 is a graph showing the relationship between the drive voltage input to the chopper circuit unit 138 and the magnitude of the current (I _CD ) supplied from the current supply unit 131 to the solenoid coil 411.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. However, the following embodiment does not limit the invention according to the claims, and all combinations of features in the embodiment are based on the invention. It is not always essential to the solution.

  FIG. 1 is a perspective view showing an appearance of a POS system 10 according to an embodiment of the present invention. As shown in FIG. 1, the POS system 10 includes a printer 100, a terminal device 200, a display device 300, a cash drawer 400, a barcode scanner 500, and the like.

  The printer 100 receives power from the external power supply 1000 via the AC adapter 700. The printer 100 issues a receipt and controls operations such as opening / closing and locking of the cash drawer 400.

  The terminal device 200 is provided with an input key for inputting a product name, a price, and the like, an operation key for performing various settings of the POS system 10, and the like. The terminal device 200 is connected to the printer 100, and sends a control command for instructing the printer 100 to issue a receipt and open / close the cash drawer 400 to the printer 100.

  The display device 300 displays information input from the terminal device 200 and the like. As will be described later, the cash drawer 400 includes a drawer tray 430 that stores cash and the like in an openable and closable manner. The barcode scanner 500 reads a barcode printed on a product by, for example, irradiating infrared light and detecting the reflected light, and transmits the content of the barcode to the printer 100.

  Hereinafter, the configurations of the printer 100 and the cash drawer 400 will be described in more detail. FIG. 2 is a functional block diagram showing internal configurations and connection relationships of the printer 100 and the cash drawer 400 in the POS system 10.

  The printer 100 includes a control unit 110, a printing unit 120, an unlocking current supply unit 130, and an opening / closing current supply unit 140. The cash drawer 400 includes a lock mechanism 410, an opening / closing drive mechanism 420, and a drawer tray 430, and is connected to the printer 100 via a connection cable 600.

  The control unit 110 controls each unit of the printer 100 according to control commands from the terminal device 200 and the barcode scanner 500. For example, when the information read from the barcode scanner 500 is input, the control unit 110 causes the printing unit 120 to print the content of the information (print data) on a print sheet such as a receipt. Further, in response to receiving a control command indicating that the drawer tray 430 of the cash drawer 400 should be opened / closed from the terminal device 200, the control unit 110 provides the lock release current supply unit 130 and the open / close current supply unit 140 with a cash command. A control command for supplying a current for driving the drawer 400 is output.

  As shown in FIG. 2, the unlocking current supply unit 130 and the switching current supply unit 140 are connected to the lock mechanism 410 and the switching drive mechanism 420 of the cash drawer 400 via the connection cable 600, respectively. In response to the control command from the control unit 110, the lock release current supply unit 130 supplies the current to the lock mechanism 410 of the cash drawer 400 to lock the drawer tray 430 or to release the lock state. . Further, the switching current supply unit 140 drives the drawer tray 430 from the stored state to the opened state where cash can be taken in and out with respect to the opening / closing drive mechanism 420 of the cash drawer 400 according to the control command from the control unit 110. Alternatively, a current for driving from the open state to the retracted state is supplied.

  FIG. 3 is a diagram illustrating an example of the structure of the lock mechanism 410. As shown in FIG. 3, the lock mechanism 410 includes a solenoid coil 411, a plunger 412, a link part 413, an engagement part 414, a fixed hook 416, and springs 417 and 418. The link part 413 is connected between the plunger 412 and the engaging part 414. Further, the engaging portion 414 is fixed so as to be rotatable about a rotation shaft 415. One end of the engaging portion 414 is linked to the link portion 413, and an engaging protrusion provided on the other end is provided in an engaging hole 431 provided in the engaged portion 431 at the rear end of the drawer tray 430 (see FIG. (Not shown). That is, the state shown in FIG. 3 shows a locked state in which the drawer tray 430 is locked by the lock mechanism 410.

  When the current is supplied from the unlocking current supply unit 130 to the solenoid coil 411, the plunger 412 moves in the unlocking direction. When the plunger 412 moves in the unlocking direction, the engaging portion 414 rotates counterclockwise (in the direction of the arrow with “A” in FIG. 3). Thereby, the engaging protrusion of the engaging portion 414 is released from the engaging hole of the engaged portion 431, and the locked state is released.

  At this time, the drawer tray 430 is pushed rightward in the drawing (opening direction) by the biasing force of the spring 418. In this example, in addition to the biasing force of the spring 418, the drawer tray 430 is driven to the open state by the opening / closing drive mechanism 420.

  On the other hand, when the drawer tray 430 is locked, the drawer tray 430 is physically pushed leftward (closed direction) in the drawing. At this time, when the engaged portion 431 of the drawer tray 430 hits the engaging protrusion of the engaging portion 414 and further pushes the drawer tray 430 in the closing direction, the engaging portion 414 turns counterclockwise (“A” is attached in FIG. 3). After rotating in the direction of the arrow), the engaging protrusion of the engaging portion 414 enters the engaging hole of the engaged portion 431 and is locked.

  FIG. 4 is a diagram illustrating an example of a circuit configuration of the unlocking current supply unit 130. As shown in FIG. 4, the unlocking current supply unit 130 includes a current supply unit 131, a diode 132, a protection circuit unit 133, a detection circuit unit 134, a reference voltage supply unit 135, a comparator 136, and an AND circuit. A circuit portion 137 and a chopper circuit portion 138 are provided.

  The protection circuit unit 133, the detection circuit unit 134, the reference voltage supply unit 135, the comparator 136, and the chopper circuit unit 138 in the unlocking current supply unit 130 are examples of the current control circuit of the present invention. Among these, the detection circuit unit 134, the reference voltage supply unit 135, and the comparator 136 are examples of the current detection unit in the current control circuit of the present invention, and the protection circuit unit 133 and the chopper circuit unit 138 are the main circuit. It is an example of the current control part in the current control circuit of the invention.

The current supply unit 131 generates a DC voltage having a predetermined magnitude (V ₁ ) based on the power supplied from the external power supply 1000 via the AC adapter 700. As a result, the current (I _CD ) for performing the above-described unlocking operation is supplied to the solenoid coil 411 in the lock mechanism 410 of the cash drawer 400. The detection circuit unit 134 detects a voltage corresponding to the magnitude of the current (I _CD ). Specifically, the detection circuit unit 134 detects the magnitude of a voltage applied to a resistor having one end installed and the other end connected to the solenoid coil 411.

The reference voltage supply unit 135 generates a DC voltage having a predetermined magnitude (V ₂ ) that serves as a reference for comparison by the comparator 136. The comparator 136 receives the voltage supplied from the reference voltage supply unit 135 and the voltage applied to the resistor in the detection circuit unit 134. The comparator 136 outputs a signal voltage of level H in a state where the magnitude of the voltage detected by the detection circuit unit 134 is lower than the magnitude of the voltage from the reference voltage supply unit 135. On the other hand, when the magnitude of the voltage detected by the detection circuit unit 134 exceeds the voltage level from the reference voltage supply unit 135, the comparator 136 outputs a signal voltage of level L.

Here, the magnitude of the voltage (V ₂ ) supplied from the reference voltage supply unit 135 is equal to the magnitude of the current supplied from the lock release current supply unit 130 to the solenoid coil 411. Is equal to the magnitude of the voltage detected by the detection circuit unit 134 when the upper limit (threshold value) of the allowable current value range is reached. Accordingly, when the magnitude of the current supplied from the unlocking current supply unit 130 to the solenoid coil 411 exceeds the threshold value, the magnitude of the detection voltage by the detection circuit unit 134 is the magnitude of the voltage from the reference voltage supply unit 135. If this value is exceeded, a level L signal voltage is output from the comparator 136.

  In this example, the comparator 136 outputs the signal voltage of level H again when a predetermined time elapses after the magnitude of the voltage detected by the detection circuit unit 134 falls below the voltage level from the reference voltage supply unit 135. To do. In addition, the comparator 136 may output a signal voltage of level H immediately when the magnitude of the voltage detected by the detection circuit unit 134 falls below the magnitude of the voltage from the reference voltage supply unit 135, instead of this example. . Alternatively, the comparator 136 may output a level H signal voltage in response to a decrease in the magnitude of the detection voltage by the detection circuit unit 134 to a predetermined level.

  The protection circuit unit 133 is provided on the input side of the chopper circuit unit 138. The protection circuit unit 133 detects the magnitude of the current input to the chopper circuit unit 138 in a state where current is supplied from the unlocking current supply unit 130 to the solenoid coil 411. And the protection circuit part 133 stops the input of the electric current to the chopper circuit part 138 according to the magnitude | size of the said detected electric current having reached the predetermined protection reference value.

  In this example, the protection reference value is set to a value larger than the threshold value. That is, the protection circuit unit 133 plays a role of preventing an inrush current from flowing into the chopper circuit unit 138, for example. In this example, the protection circuit unit 133 outputs a signal indicating that the chopper circuit unit 138 may be normally operated when the magnitude of the current input to the chopper circuit unit 138 is lower than the protection reference value. To do.

The AND circuit unit 137 receives an output voltage from the comparator 136 and a control signal indicating that the lock state of the lock mechanism 410 of the cash drawer 400 should be released from the control unit 110. The AND circuit unit 137 also receives the signal from the protection circuit unit 133. The AND circuit unit 137 outputs the drive voltage (V _CH ) of the chopper circuit unit 138 according to the input state of each signal.

More specifically, when the level H signal is input from the comparator 136, the control signal is input from the control unit 110, and the signal is input from the protection circuit unit 133, The magnitude of the drive voltage (V _CH ) output from the AND circuit unit 137 is V ₀ . On the other hand, when the signal from the comparator 136 is level L, when the control signal is not input from the control unit 110, or when the signal is not input from the protection circuit unit 133, the AND circuit unit 137 The magnitude of the drive voltage (V _CH ) output from the terminal is zero.

The chopper circuit unit 138 is a chopper circuit capable of high-speed chopping with respect to the current supplied from the current supply unit 131 to the solenoid coil 411, and the magnitude of the drive voltage (V _CH ) input from the AND circuit unit 137. Accordingly, the supply and stop of the current from the current supply unit 131 to the solenoid coil 411 are switched. More specifically, the chopper circuit unit 138 is supplied with a current from the current supply unit 131 to the solenoid coil 411 when a drive voltage (V _CH ) having a magnitude of V ₀ is input from the AND circuit unit 137. Switch the circuit to. On the other hand, the chopper circuit unit 138 receives a current from the current supply unit 131 to the solenoid coil 411 when the drive voltage (V _CH ) is not input from the AND circuit unit 137 (the magnitude of V _CH is 0). Stop supplying.

  That is, for example, when a non-standard cash drawer 400 is connected to the printer 100, the magnitude of the current supplied from the unlocking current supply unit 130 to the solenoid coil 411 can flow through the circuit of the unlocking current supply unit 130. When the magnitude of the detected voltage by the detection circuit unit 134 exceeds the magnitude of the voltage from the reference voltage supply unit 135 due to exceeding the possible threshold, the chopper circuit unit 138 causes the current supply unit 131 to supply the solenoid coil 411. Stop supplying current.

  Further, the chopper circuit unit 138 receives the solenoid signal from the current supply unit 131 even when the control signal indicating that the lock mechanism 410 of the cash drawer 400 of the cash drawer 400 should be released is not input from the control unit 110 to the AND circuit unit 137. The supply of current to the coil 411 is stopped. Further, the chopper circuit unit 138 stops the input of the current to the chopper circuit unit 138 even when the protection circuit unit 133 detects an inflow of a current exceeding the protection reference value such as an inrush current.

FIG. 5 is a graph showing the relationship between the drive voltage input to the chopper circuit unit 138 and the magnitude of the current (I _CD ) supplied from the current supply unit 131 to the solenoid coil 411. In this figure, the state in which the chopper circuit unit 138 controls the magnitude of the current (I _CD ) when no inflow of current exceeding the protection reference value such as inrush current is detected in the protection circuit unit 133. It is shown.

5, when the control signal to the effect that release the locked state of the locking mechanism 410 of the cash drawer 400 from the control unit 110 to the AND circuit 137 is input at time _{T 0,} the _{T 1} from the time _{T 0,} the solenoid The current (I _CD ) gradually increases according to circuit characteristics such as the inductance of the coil 411. Then, when the magnitude of the current (I _CD ) reaches the threshold (I ₀ ) that can be passed through the unlocking current supply unit 130 at time T ₁ , the signal from the comparator 136 switches from level H to level L. As a result, the chopper circuit unit 138 cuts off the current (I _CD ) supply circuit from the current supply unit 131 to the solenoid coil 411. Thereby, from time T ₁ to T ₂ , the current (I _CD ) gradually decreases from the threshold value (I ₀ ) according to circuit characteristics such as the inductance of the solenoid coil 411.

Then, when the signal from the comparator 136 is switched from the level L to the level H at a time T ₂ after a predetermined time has elapsed after the current (I _CD ) falls below the threshold (I ₀ ), the chopper circuit unit 138 supplies current. A circuit for supplying current (I _CD ) from the unit 131 to the solenoid coil 411 is connected, and supply of the current (I _CD ) is resumed. When the magnitude of the current (I _CD ) reaches the threshold value (I ₀ ) at time T ₃ , the signal from the comparator 136 switches again from the level H to the level L, and the current supply unit 131 transfers to the solenoid coil 411. Current (I _CD ) supply circuit is cut off.

In this way, the unlocking current supply unit 130 of this example supplies the solenoid coil 411 from the current supply unit 131 even when the cash drawer 400 having the non-standard low inductance solenoid coil 411 is connected to the printer 100, for example. The magnitude of the generated current does not exceed the circuit threshold, and the circuit can be prevented from malfunctioning. Unlike the circuit protection element that needs to be replaced once the circuit is interrupted by detecting an overcurrent such as a fuse, the unlocking current supply unit 130 of this example uses the chopper circuit unit 138 to supply and stop current. In this method, the magnitude of the current flowing in the circuit is controlled by controlling the switching. As a result, the circuit can be protected from overcurrent without stopping the supply of current to the lock mechanism 410 of the cash drawer 400. Also, in this example, by setting the switching timing by the chopper circuit unit 138 so that the effective value of the current (I _CD ) after time T _{1 in} FIG. 5 becomes a current value at which the lock mechanism 410 can operate, The operation of the lock mechanism 410 is not affected.

DESCRIPTION OF SYMBOLS 10 ... POS system, 100 ... Printer, 110 ... Control part, 120 ... Printing part, 130 ... Unlock current supply part, 131 ... Current supply part, 132 ... Diode, 133 ... Protection circuit part, 134 ... Detection circuit part, 135 Reference voltage supply unit, 136 ... Comparator, 137 ... AND circuit unit, 138 ... Chopper circuit unit, 140 ... Switching current supply unit, 200 ... Terminal device, 400 ... Cash drawer, 410 ... Lock mechanism, 411 ... Solenoid coil, 412 ... Plunger, 413 ... Link part, 414 ... Engagement part, 415 ... Rotating shaft, 416 ... Fixed hook, 417, 418 ... Spring, 420 ... Opening / closing drive mechanism, 430 ... Drawer tray, 431 ... Engaged part, 500 ... Barcode scanner, 600 ... Connection cable, 700 ... AC adapter, 1000 ... External power supply

Claims (4)

A current control circuit for controlling a current supplied to a solenoid coil of a cash drawer,
A current detector that outputs a signal voltage in a state where the current is below a predetermined threshold;
A chopper circuit section for switching supply and stop of the current by chopping;
A protection circuit unit that outputs a signal in a state where the magnitude of the current input to the chopper circuit unit is lower than a predetermined protection reference value;
An AND circuit unit that outputs a driving voltage to the chopper circuit unit,
The current control circuit , wherein the signal voltage from the current detection unit and the signal from the protection circuit unit are input to the AND circuit unit . The current control circuit according to claim 1 , wherein a control signal indicating that the cash drawer is to be unlocked is further input to the AND circuit unit . The chopper circuit unit switches to a state in which a current is supplied to the solenoid coil when the drive voltage from the AND circuit unit is input, and a current to the solenoid coil when the drive voltage is not input. The current control circuit according to claim 1, wherein the current control circuit is stopped. A printer connected to a cash drawer,
A printing unit for printing on printing paper based on given print data;
A current supply unit for supplying current to the cash drawer;
A current control circuit for controlling the supply of the current,
The current control circuit is
A current detector that outputs a signal voltage in a state where the current is below a predetermined threshold;
A chopper circuit section for switching supply and stop of the current by chopping;
A protection circuit unit that outputs a signal in a state where the magnitude of the current input to the chopper circuit unit is lower than a predetermined protection reference value;
An AND circuit unit that outputs a driving voltage to the chopper circuit unit,
The printer, wherein the AND circuit unit receives the signal voltage from the current detection unit and the signal from the protection circuit unit .

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