CN211827459U - Capacitive coupling detection anti-dismantling device and POS machine - Google Patents

Abstract

The capacitive coupling detection and tamper-proof device and POS machine of the present application add a coupling capacitive tamper-proof structure on the basis of the traditional tamper-proof structure, and the coupling capacitor does not directly use the Tamper signal, so that the detection voltage obtained by coupling the coupling capacitor to the Tamper signal is obtained. The signal will not be directly exposed to the tamper switch, which improves the security of detecting electrical signals and the difficulty of being attacked. The detection circuit detects the capacitance voltage of the coupling capacitor to output the detection electrical signal, which improves the detection accuracy, the realization method and the circuit are simple and reliable, and the latter stage of the detection circuit can continue to expand other control circuits.

Description

Capacitive coupling detection anti-dismantling device and POS machine

technical field

The application belongs to the field of electronic circuits, and in particular relates to a capacitive coupling detection and anti-disassembly device and a POS machine.

Background technique

Tamper signal line: a signal line whose level changes can be detected by the detection circuit. When the detection circuit detects that the level on the signal line is inconsistent with the set level value, the detection circuit will trigger the security mechanism to erase the password. keys and other sensitive information. Tamper switch: An tamper-proof mechanism with a Tamper signal, once the tamper switch is disengaged, the detection circuit will trigger the security mechanism, erasing the key and other sensitive information;

At present, the known tamper switch controls the on-off of the tamper signal through the pressing of carbon particles or dome pieces, so as to realize the function of the tamper switch. Since the tamper signal is directly on the switch, it is easy to be detected. The cracking fails, and there are only two valid contacts, and it is also easy to be attacked and failed. It can be seen that the anti-attack ability of the tamper switch is weak.

Utility model content

The purpose of the present application is to provide a capacitively coupled detection anti-disassembly device and a POS machine, which aims to solve the problem that the traditional anti-disassembly switch has two effective contacts, and the anti-attack capability is weak.

A first aspect of the embodiments of the present application proposes a capacitively coupled detection and tamper-proof device, which is arranged on a circuit substrate and includes:

At least one anti-dismantling structure, the anti-dismantling structure includes a first signal contact and a conductive connection piece provided on the first conductive layer of the circuit substrate for accessing the Tamper signal, and the conductive connection piece connects the first Signal contacts are covered and welded or directly pressed;

at least one coupling conductive sheet, the coupling conductive sheet is arranged on the second conductive layer of the circuit substrate, each of the coupling conductive sheets is arranged opposite to one of the anti-removal structures to form a coupling capacitor; and

A detection circuit, the detection circuit is connected to the coupling conductive sheet, and the detection circuit is used for outputting a detection electrical signal for the capacitance change of the coupling capacitor.

In one of the embodiments, each of the tamper-resistant structures further includes at least one second signal contact, the second signal contact being electrically isolated from the first signal contact on the first conductive layer, The conductive connection piece covers the first signal contact and the second signal contact and solders or directly presses them.

In one of the embodiments, the detection circuit includes:

an access circuit, the input end of the access circuit is connected to the coupling conductive sheet, and a driving voltage is output based on the voltage of the coupling capacitor;

a switch tube, the control end of the switch tube is connected to the output end of the access circuit, and the switch tube is turned on and off under the driving of the driving voltage, so as to connect to the first conduction end or the second conduction end of the switch tube The detection electrical signal is output.

In one embodiment, the access circuit includes a diode and a capacitor, the anode of the diode is used as the input terminal of the access circuit, and the cathode of the diode is connected to one end of the capacitor and serves as the connection terminal. into the output end of the circuit, and the other end of the capacitor is grounded.

In one embodiment, the access circuit further includes a pull-up resistor or a pull-down resistor, and the pull-up resistor or the pull-down resistor is connected to the cathode of the diode.

In one embodiment, the switch transistor is an NPN transistor or an NMOS transistor.

In one embodiment, the tamper-proof structure further includes a protection signal ring provided on the first conductive layer, and the protection signal ring is electrically isolated around the first signal contact and the second signal the outer side of the contact, and the protection signal ring is electrically isolated from the conductive connection piece.

In one embodiment, the protection signal ring, the first signal contact and the second signal contact are gold fingers or exposed copper layers disposed on the first conductive layer.

In one embodiment, the first conductive layer is a surface layer of the circuit substrate, and the second conductive layer is a middle layer of the circuit substrate.

A second aspect of the embodiments of the present application provides a POS machine, which includes the capacitively-coupled detection and tamper-proof device as described above.

The above-mentioned capacitive coupling detection tamper-proof device adds a coupling capacitive tamper-proof structure on the basis of the traditional tamper-proof structure, and the coupling capacitor does not directly use the Tamper signal, so that the detection electrical signal obtained by coupling the coupling capacitor to the Tamper signal will not be directly. Exposure to the tamper switch improves the security of electrical signal detection and the difficulty of being attacked. In the present application, the detection circuit detects the capacitance voltage of the coupling capacitor to output the detection electrical signal, which improves the detection accuracy, the implementation method and circuit are simple and reliable, and the latter stage of the detection circuit can continue to expand other control circuits.

Description of drawings

FIG. 1 is a schematic structural diagram of a circuit substrate of a capacitively coupled detection and anti-disassembly device provided by an embodiment of the present application;

FIG. 2 is a schematic structural diagram of the capacitive coupling detection and anti-disassembly device provided by the first embodiment of the present application;

3 is a schematic structural diagram of a capacitively coupled detection and anti-disassembly device provided by the second embodiment of the present application;

FIG. 4 is a schematic structural diagram of a capacitively coupled detection and tamper-proof device according to a third embodiment of the present application.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application will be described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application.

It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

It is to be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top" , "bottom", "inside", "outside", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, which are only for the convenience of describing the application and simplifying the description, rather than indicating or implying the indicated device. Or elements must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as a limitation of the present application.

In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined as "first" or "second" may expressly or implicitly include one or more of that feature. In the description of the present application, "plurality" means two or more, unless otherwise expressly and specifically defined.

Please refer to FIG. 1 . The capacitive coupling detection and anti-disassembly device provided by an embodiment of the present application, which can be applied to a POS (Point of Sales, point of sale information management system) machine, is disposed on a circuit substrate. The circuit substrate in this embodiment is multi- The laminate has a first conductive layer L1 on the surface layer and a second conductive layer L2 on the middle layer. The electrical signal on the middle layer is not easy to be detected, so it can improve the security of the tamper-proof device; in other implementations In an example, the circuit substrate is a plurality of single-layer boards, and the first conductive layer L1 and the second conductive layer L2 are respectively located on different single-layer boards.

Please refer to FIG. 1 to FIG. 3 , the capacitively-coupled detection and tamper-proof device includes at least one tamper-proof structure 100 , at least one coupling conductive sheet and at least one detection circuit. The tamper-proof structure 100 includes the first conductive layer L1 disposed on the circuit substrate for For connecting the first signal contact P1 and the conductive connecting piece (not shown) of the Tamper signal, the conductive connecting piece covers the first signal contact P1 and welds or directly presses it. The anti-dismantling structure 100 is a traditional In the tamper-resistant structure 100, the first signal contact P1 is one or two or more electrically isolated on the first conductive layer L1. The conductive connecting piece is a conductive material such as dome, carbon particles, exposed copper FPC or copper foil.

The coupling conductive sheets 200 are disposed on the second conductive layer L2 of the circuit substrate, and each coupling conductive sheet 200 is disposed opposite to a tamper-proof structure 100 to form a coupling capacitor C0; it can be understood that the tamper-proof structure 100 and the coupling conductive sheet 200 The number should be equal, the first signal contact P1 of the anti-dismantling structure 100 and the conductive connecting piece constitute one pole plate of the coupling capacitor C0, and the coupling conductive plate 200 constitutes the other pole plate of the coupling capacitor C0. The exposed copper opened on the second conductive layer L2 of the coupling conductive sheet 200, or the conductive metal sheet welded on the second conductive layer L2.

The detection circuit 300 is connected to the coupling conductive sheet 200, and the detection circuit 300 is used for the capacitance change of the coupling capacitor C0 to output a detection electrical signal. It can be understood that the detection circuit 300 can be one, and simultaneously detects the voltage of multiple coupling capacitors C0, or It is equivalent to the number of coupling capacitors C0, and is connected to each coupling capacitor C0 to detect its voltage. During the detection process of the coupling capacitor C0 by the detection circuit 300, a default level signal is output in a normal state to indicate that the tamper-proof device is normal. When the change in the voltage of the coupling capacitor C0 is detected by the detection circuit 300 to change the output level state, then Indicates that a tamper has been attacked or removed.

It can be seen that the capacitively coupled detection anti-tamper device adds a coupling conductive sheet 200 to the different conductive layers of the original anti-tamper structure 100 to form a coupling capacitor C0, and confirms the Tamper signal by detecting the voltage change on the coupling conductive sheet 200. state to achieve the purpose of tamper-proof protection, because the coupling conductive sheet 200 is on the inner layer of the circuit substrate and is not directly exposed outside the circuit substrate, which is beneficial to improve the security of the Tamper signal itself. This solution can not only prevent the detection mechanism of the change of the coupling capacitor C0, but also ensure that the Tamper signal is far away from the tamper point, which improves the security of the Tamper signal itself against detection.

Referring to FIG. 4, in one embodiment, each tamper-proof structure 100 further includes at least one second signal contact N1, and the second signal contact N1 is electrically connected to the first signal contact P1 on the first conductive layer L1 For isolation, the first signal contact P1 and the second signal contact N1 are covered by the conductive connecting piece and welded or directly pressed together. The first signal contact P1, the second signal contact N1 and the conductive connecting piece in the tamper-proof structure 100 constitute a traditional tamper-proof switch. For the capacitive coupling detection tamper-proof device, there are two conductive layers of Tamper signal. Anti-tamper detection mechanism improves safety. Compared with the embodiment of FIG. 4 , in the embodiments of FIGS. 2 and 3 , the second signal contact N1 of the tamper-proof structure 100 is removed (or arranged at other positions), thereby breaking away from the original traditional tamper-proof structure, and can be used in Many tamper switches are extended on the basis of a Tamper signal, refer to Figure 3.

Referring to FIG. 2 to FIG. 4, in one embodiment, the detection circuit 300 includes: an access circuit 302 and a switch Q1. The input terminal of the access circuit 302 is connected to the coupling conductive sheet 200, and the driving voltage V1 is output based on the voltage of the coupling capacitor C0; the control terminal of the switch Q1 is connected to the output terminal of the access circuit 302, and the switch Q1 is driven by the driving voltage V1 It is turned on and off, so as to output a detection electrical signal at its first conducting end or second conducting end.

In one embodiment, the access circuit 302 includes a diode D1 and a capacitor C1, the anode of the diode D1 is used as the input end of the access circuit 302, the cathode is connected to one end of the capacitor C1, and is used as the output end of the access circuit 302, the capacitor The other end of C1 is grounded. The access circuit 302 further includes a pull-up resistor or a pull-down resistor, and the pull-up resistor or the pull-down resistor is connected to the cathode of the diode D1. The switch Q1 is an NPN transistor or an NMOS transistor. In this embodiment, the collector of the NPN transistor or the drain of the NMOS transistor is used as the output terminal P0 of the detection circuit 300 .

The signal to be detected (Tamper signal) outputs the driving voltage V1 to the detection circuit 300 from the first signal contact P1 (or other useful signals) through the coupling capacitor C0. When the conductive connecting piece is pressed well, the value of the coupling capacitor C0 is relatively large. When the value of the coupled drive voltage V1 is greater than the turn-on voltage of the switch tube Q1, the switch tube Q1 will be turned on, which will pull down the detection electrical signal at the output terminal P0 of the detection circuit 300, and keep it in a non-triggered state. The conductive connecting piece of the dismantling structure 100 is loosened, resulting in a decrease in the coupling capacitor C0. At this time, the driving voltage V1 also decreases and cannot reach the turn-on voltage of the switch tube Q1, and the switch tube Q1 is turned off, resulting in the output end P0 of the detection circuit 300. The detection electrical signal becomes high, which leads to triggering, thereby judging whether the tamper switch has been disassembled.

Among them, the change of the value of the capacitor C1 can adjust the size of the voltage driving voltage V1, the diode D1 plays the role of forward conduction and reverse cutoff, and at the same time, a pull-up resistor or pull-down resistor can be added to the driving voltage V1 to change the driving voltage V1. The initial value, the rear end of the output terminal P0 of the output detection circuit 300 can continue to expand other control circuits, the conductive connection piece is normally pressed and the switch tube Q1 is turned on, the output detection electrical signal is low level, and the conductive connection piece is released. The state switch tube Q1 is turned off, and the output detection electrical signal is a high level.

In one embodiment, the tamper-proof structure 100 further includes a protection signal ring 105 disposed on the first conductive layer L1 , and the protection signal ring 105 is electrically isolated around the first signal contact P1 and the second signal contact N1 and protect the electrical isolation of the signal ring 105 from the conductive connection piece. The protection signal ring 105 can provide the tamper-resistant structure 100 with tamper-proof protection at the outermost side. When the protection signal ring 105 is electrically connected with the conductive connecting piece, the electrical parameters loaded on the protection signal ring 105 are changed to cause triggering.

In one embodiment, the protection signal ring 105, the first signal contact P1 and the second signal contact N1 are gold fingers or exposed copper layers disposed on the first conductive layer L1.

The capacitive coupling detection and tamper-proof device of the present application adds an internal detection signal of the PCB board that cannot be directly detected to the original traditional tamper-proof structure, thereby greatly enhancing the security of the tamper-proof switch and the difficulty of being attacked . The coupling capacitor couples the Tamper signal instead of directly connecting it, so that the Tamper signal of the coupling capacitor detection part is not directly exposed to the tamper-proof device, which improves the security of the Tamper signal itself. The detection circuit 300 uses the rectification characteristics of the diode D1 and the capacitor C1 or the pull-up and pull-down resistors to control the size of the driving voltage V1 to control the conduction state of the switch tube Q1, so as to achieve the detection accuracy, and at the same time, the implementation method and circuit are simple and reliable. In addition, The latter stage of the detection circuit can also continue to expand other control circuits.

The above-mentioned embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the above-mentioned embodiments, those of ordinary skill in the art should understand that: it can still be used for the above-mentioned implementations. The technical solutions described in the examples are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions in the embodiments of the application, and should be included in the within the scope of protection of this application.

Claims (10)

1. The utility model provides a capacitive coupling formula detects anti-disassembly device, locates on the circuit substrate, its characterized in that includes:

the anti-disassembly structure comprises a first conductive layer arranged on the circuit substrate, a first signal contact for accessing a Tamper signal and a conductive connecting sheet, and the conductive connecting sheet covers the first signal contact and welds or directly presses the first signal contact;

the coupling conducting strips are arranged on the second conducting layer of the circuit substrate, and each coupling conducting strip is arranged opposite to one anti-dismounting structure to form a coupling capacitor; and

and the detection circuit is connected with the coupling conducting strip and is used for outputting a detection electric signal according to the capacitance change of the coupling capacitor.

2. The capacitively coupled sensing tamper-evident device of claim 1, wherein each of the tamper-evident structures further comprises at least one second signal contact electrically isolated from the first signal contact on the first conductive layer, and the conductive connecting pad overlays and either welds or directly presses the first signal contact and the second signal contact.

3. The capacitively-coupled detection tamper apparatus of claim 1, wherein the detection circuit comprises:

the input end of the access circuit is connected with the coupling conducting strip, and the drive voltage is output based on the voltage of the coupling capacitor;

and the control end of the switch tube is connected with the output end of the access circuit, and the switch tube is switched on and off under the driving of the driving voltage so as to output the detection electric signal at the first conduction end or the second conduction end of the switch tube.

4. The capacitively coupled test tamper evident device of claim 3, wherein the access circuit includes a diode and a capacitor, an anode of the diode being an input of the access circuit, a cathode of the diode being connected to one end of the capacitor and being an output of the access circuit, and another end of the capacitor being connected to ground.

5. The capacitively coupled detection tamper resistant device of claim 4, wherein the access circuit further comprises a pull-up resistor or a pull-down resistor, the pull-up resistor or the pull-down resistor connected to the cathode of the diode.

6. The capacitively coupled tamper-evident device of claim 3, wherein the switch tube is an NPN transistor or an NMOS tube.

7. The capacitively-coupled sensing tamper-evident device of claim 2, wherein the tamper-evident structure further comprises a guard signal ring disposed on the first conductive layer, the guard signal ring being electrically isolated around the outside of the first signal contact and the second signal contact, and the guard signal ring being electrically isolated from the conductive connecting pad.

8. The capacitively-coupled test tamper of claim 7, wherein the guard signal ring, the first signal contact and the second signal contact are gold fingers or copper exposed layers disposed on the first conductive layer.

9. The capacitively-coupled test tamper of any of claims 1 to 6, wherein the first conductive layer is a surface layer of the circuit substrate and the second conductive layer is an intermediate layer of the circuit substrate.

10. A POS machine comprising a capacitively coupled detection tamper evident device of any one of claims 1 to 9.

Images