A tamperproof circuit

Abstract

The application relates to a tamper-proof circuit which comprises a first power supply, a second power supply, a detection switch, an alarm and an alarm switch, one end of the detection switch is connected with one end of the first power supply, the other end of the detection switch is connected with the control end of the alarm switch, the alarm and the alarm switch are connected in series and then connected in the second power supply power supply loop; the detection switch turns on the alarm switch when the shell is forcibly opened, and the alarm alarms in response to the turn-on of the second power supply power supply loop. The application alarms when the shell of a device to be protected is illegally opened, thereby protecting the device.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electronic circuit, in particular to a tamper-proof circuit. BACKGROUND

[0002] With the rapid development of social economy, the Internet, computer and other information technology rise and penetrate into all aspects of society. Among them, many electronic products, control devices are not allowed to be illegally operated by irrelevant personnel for security reasons, especially not allowed to open the shell of the device or product. SUMMARY

[0003] In view of the technical problems existing in the prior art, the present application provides a tamper-proof circuit applied to electronic products or control devices to prevent the products or devices from being illegally disassembled.

[0004] In order to solve the above technical problems, according to one aspect of the present application, the present application provides a tamper-proof circuit installed in the shell of a device to be protected, comprising a first power supply, a second power supply, a detection switch, an alarm and an alarm switch, wherein one end of the detection switch is connected to one end of the first power supply, the other end of the detection switch is connected to the control end of the alarm switch, and the alarm and the alarm switch are connected in series in the second power supply power supply circuit; the detection switch turns on the alarm switch when the shell is forcibly opened, and the alarm alarms in response to the second power supply power supply circuit being turned on.

[0005] According to another aspect of the present application, the present application provides a tamper-proof circuit installed in the shell of a device to be protected, comprising a first power supply, a second power supply, a detection switch in an open state, an alarm and a first triode, wherein the first end of the detection switch is connected to the first power supply, the second end of the detection switch is connected to the base of the first triode through a base resistor; the collector of the first triode is connected to the first end of the alarm, the emitter of the first triode is connected to the second power supply of the first power supply; the second end of the alarm is connected to the power supply end of the second power supply; the detection switch is turned on when the shell is forcibly opened, and the alarm alarms.

[0006] The tamper-proof circuit provided by the present application can alarm when the device to be protected is illegally operated, and further can make the device to be protected stop working, thereby ensuring the safety of data transmission of the device to be protected. BRIEF DESCRIPTION OF DRAWINGS

[0007] Hereinafter, the preferred embodiments of the present application will be further described in detail with reference to the accompanying drawings, in which:

[0008] Figure 1 is a schematic diagram of a tamper-proof circuit according to an embodiment of the present application;

[0009] Figure 2 is a schematic diagram of the appearance of a device with an anti-tamper circuit according to an embodiment of the present application;

[0010] Figure 3 is a schematic diagram of the detection switch principle according to an embodiment of the present application;

[0011] Figure 4 is a schematic diagram of the position relationship between the housing of the device to be protected and the Hall switch according to an embodiment of the present application;

[0012] Figure 5 is a schematic diagram of the housing sealing structure of the device to be protected according to an embodiment of the present application;

[0013] Figure 6 is a schematic diagram of the detection switch circuit principle according to an embodiment of the present application;

[0014] Figure 7 is a schematic diagram of the double-layer housing of the device to be protected according to an embodiment of the present application; and

[0015] Figure 8 is a schematic diagram of the double-layer housing of the device to be protected according to another embodiment of the present application. DETAILED DESCRIPTION

[0016] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0017] In the following detailed description, reference can be made to the various drawings that form a part hereof, and which are used to illustrate specific embodiments of the present application. In the drawings, like numerals describe substantially similar components throughout the several views. Specific embodiments of the present application are described in enough detail to enable those skilled in the art to practice the technical solutions of the present application. It should be understood that other embodiments can be utilized and structural, logical, and electrical changes can be made without departing from the scope of the present application.

[0018] Figure 1It is the anti-disassembly circuit principle according to one embodiment of the present application, the anti-disassembly circuit in the embodiment includes first power supply X20, second power supply 12V_in, detection switch X19, alarm beep and alarm switch, wherein, the first end of the detection switch X19 is connected with the positive pole of the first power supply X20, namely the power supply end, the second end of the detection switch X19 is connected with the control end of the alarm switch. In the present application, the alarm switch is a switching triode Q1, the second end of the detection switch X19 is connected with the base of the switching triode Q1 through a base resistor, the collector of the switching triode Q1 is connected with one end of the alarm beep, the other end of the alarm beep is connected with the second power supply 12V_in, and the emitter of the switching triode Q1 is connected with the negative pole of the first power supply X20. When the detection switch X19 detects that the shell is forcibly opened, it is closed, the first power supply X20 provides the base current for the switching triode Q1 to make the switching triode Q1 saturated and conductive, then the second power supply power supply circuit where the alarm beep is located is connected, and the alarm beep alarms. In the embodiment, the first power supply X20 is a battery with two series 1.5V batteries, and the second power supply 12V_in is the input power supply of the device to be protected, which provides 12V DC voltage. Of course, according to the power supply parameters of the alarm, the first power supply or the battery can also be used as the second power supply.

[0019] The present application alarms when the shell of the device to be protected is forcibly opened, to prompt that the shell is currently being illegally opened.

[0020] In the embodiment, the alarm beep is a buzzer, of course, it can also be an audible and light alarm or a detector sending alarm information and connected to the related monitoring device. When the shell is forcibly opened, the detector sends a high level representing alarm information, and after the monitoring device receives the high level signal sent by the detector, it is determined that the shell of the device to be protected is being forcibly opened, and then alarms, such as sending alarm information to the related personnel, or cutting off the power supply of the device, etc.

[0021] As for the installation position of the alarm, it can be located in the device to be protected, or installed away from the device to be protected, such as a monitoring room, etc., to facilitate the monitoring personnel to obtain the alarm information immediately.

[0022] Further, in order to make the device to be protected stop working immediately when it is illegally operated, the anti-disassembly circuit further includes a device power supply protector F1 and a first power supply switch. The first power supply switch is a switching triode Q2, the base of which is connected with the positive pole of the first power supply X20 through the detection switch X19, the collector of the switching triode Q2 is connected with the second end of the power supply protector F1 in the device power supply circuit, and the emitter of the switching triode Q2 is connected with the negative pole of the first power supply X20. The power supply protector F1 can be any type of fuse, such asFigure 1 The first end of the power protector F1 is connected to the power supply of the device to be protected, and the power supply after passing through the power protector F1 is used to supply power to the circuit of the device. The first end of the power protector F1 is also connected to the positive electrode of the second power source X20 through a diode D1.

[0023] When the shell is opened illegally, the detection switch X19 is closed, the base of the switch triode Q2 is connected to the first power source X20, and the base current provided by the first power source X20 makes the switch triode Q2 enter a saturated state instantaneously, and the collector and the emitter are turned on, so that the first power source X20 and the power protector F1 form a closed circuit loop, thereby causing the power protector F1 to be fused due to the instantaneous excessive current flowing through it, thereby cutting off the power supply circuit of the device to be protected.

[0024] Figure 2 A schematic diagram of the appearance of a device to be protected using the anti-disassembly circuit of the present application. The device to be protected is an audio and video physical isolation device, which is used to physically isolate audio and video signals of different networks, so as to ensure that the information of each network is not leaked. In this embodiment, the device to be protected includes a shell 1, which includes a front panel and a rear panel, and various interfaces are provided on the panels for connecting audio and video signals. The inside of the shell 1 is the circuit of the device, and various electrical components are installed on the electrical board, which is fixed with the bottom plate of the shell.

[0025] Among them, the power interface of the device is connected to a power adapter, and the 220V mains power is converted by the power adapter to provide a 12V power supply for the device. The anti-disassembly circuit provided by the present application is connected to the circuit board near the power interface, and the detection switch is installed at the connection of the shell. The detection switch involved in the present application is, for example, the D3SH-BIRI type detection switch of OMRON company, the structure diagram of which is as shown in Figure 3 The two pins 22 are respectively connected in the circuit. In the normal state of the shell, the detection switch is in an open state, and when the shell is opened illegally, the operating rod 21 of the detection switch is pressed down to make the detection switch closed, thereby alarming and disconnecting the power supply circuit of the device.

[0026] The aforementioned detection switch can be a travel switch, a micro switch, or a proximity switch, a Hall switch. As Figure 4The diagram shows the positional relationship between the housing and the Hall switch. The housing 11 and housing 12 of the device to be protected are interlocked. The circuitry of the device to be protected and the tamper-proof circuit provided by this invention are mounted on a circuit board 13, which is fixed inside the housing 12. The Hall switch X30 is fixed to the circuit board 13. A magnet X31 is mounted on the bottom end of the mounting bracket X32 on the housing 11. When the housing 11 separates from the housing 12, the mounting bracket X32 moves with the housing 11, and the magnet X31 on it approaches the Hall switch X30, causing the Hall switch X30 to turn on.

[0027] The installation principle of proximity switches is similar to that of Hall effect switches. The stop block that enables the proximity switch to turn on is fixed to the housing and moves with the housing. When the housing is opened, the stop block enters the response range of the proximity switch, thereby turning on the proximity switch.

[0028] The detection switch described in this invention can also be a relay contact switch, and with the help of necessary sensors, it can also achieve the function of a detection switch.

[0029] This invention also provides an anti-tamper structure, which includes a housing of the device to be protected with a special structure, and is equipped with an anti-tamper circuit, which can serve to trigger an alarm when the housing of the device to be protected is illegally operated. Figure 5 As shown, the housing of the device to be protected is a sealed structure. Sealing strips 20 are connected between the housings 21 and between the housing and the interface 22, thereby ensuring that the interior of the housing of the device to be protected is a sealed space. Oxygen is removed from this sealed space, and inert gas is introduced. Figure 6 This is a schematic diagram of the detection switch circuit in the circuit designed to work with the special housing structure. The detection switch circuit includes an oxygen sensor X40 housed within a sealed space and a detection switch control circuit. The detection switch control circuit includes a microcontroller X41, a switching transistor X42, and a relay circuit. The relay circuit includes a relay coil X43 and a pair of normally open contacts X44. The signal terminal of the oxygen sensor X40 is connected to one of the input terminals of the microcontroller X41. One output terminal of the microcontroller X41 is connected to the base of the transistor X42. The collector of the transistor X42 is connected to the power supply Vcc. The emitter of the transistor X42 is connected to one end of the relay coil X43, and the other end of the relay coil X43 is grounded. The normally open contact X44 serves as the detection switch, such as... Figure 1 As shown, the first end of the normally open contact X44 is connected to the positive terminal of the first power supply X20, and the second end is connected to the base of the switching transistors Q1 and Q2 through base resistors respectively.

[0030] Oxygen sensor X40, located in a sealed space, sends the sensed oxygen concentration value to microcontroller X41. Microcontroller X41 has a built-in oxygen concentration threshold and compares the sensed oxygen concentration value with the threshold. When the sensed oxygen concentration value is greater than the threshold, microcontroller X41 outputs a high-level signal. Under normal circumstances, the oxygen concentration in the sealed space is very low, and the sensed oxygen concentration value is less than the threshold, so microcontroller X41 does not output anything. However, when the housing is illegally opened, the sealed environment is disrupted, and external oxygen enters the housing. The oxygen concentration sensed by the oxygen sensor exceeds the threshold, and microcontroller X41 outputs a high-level signal, causing transistor X42 to saturate and conduct. This connects the collector and emitter of transistor X42, energizing the relay coil X43 and triggering its normally open contact X44 to close, thus activating the alarm and switching the power supply to the protected device.

[0031] In another embodiment, the housing comprises a double-layered housing, such as Figures 7-8 As shown, the device to be protected includes double-layered housings 31 and 32, dividing the internal space of the device into two spaces. Housings 31 and 32 are sealed together by a sealing strip 30, making one of the spaces a sealed space 310. Figure 7 In the middle, the interior of the housing 31 is a sealed space 310, and the circuit board 33 is located in the space between the housing 31 and the housing 32. Figure 8 In this design, the space between housings 31 and 32 is a sealed space 310. Various electrical components 34 are mounted on a circuit board 33 within this enclosed space. An oxygen sensor is housed within this sealed space 310, which is filled with inert gas at a concentration lower than a preset level. When the housing is opened, outside air enters the sealed space 310, increasing the oxygen concentration. If this concentration exceeds the sensing threshold, the microcontroller outputs a high-level signal to the detection switch, triggering an alarm and cutting off the power to the protected device, thus stopping its operation.

[0032] Due to sealing and other reasons, the inert gas in the sealed space may leak to varying degrees, causing the oxygen concentration in the space to increase and leading to malfunctions. To solve this problem, in another embodiment, an oxygen scavenger can be placed in the sealed space filled with inert gas to maintain the oxygen content in the sealed space below a preset concentration. The oxygen scavenger can be an inorganic matrix-based oxygen scavenger, such as placing reduced iron powder in a small bag and placing it in the sealed space.

[0033] This invention provides an anti-tamper circuit within the housing of the protected device. When the device is illegally operated, an alarm is triggered, and the power supply circuit of the device is cut off, causing the protected device to stop working, thereby ensuring the security of the data transmitted by the protected device.

[0034] The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the scope of the invention. Therefore, all equivalent technical solutions should also fall within the scope of the invention.

Claims

1. A tamper-proof circuit, installed inside the housing of a device to be protected, wherein the tamper-proof circuit includes a first power supply, a second power supply, a detection switch, an alarm, an alarm switch, an oxygen sensor, and a detection switch control circuit, wherein, One end of the detection switch is connected to one end of the first power supply, and the other end of the detection switch is connected to the control terminal of the alarm switch. The alarm and the alarm switch are connected in series in the second power supply circuit. The detection switch turns on the alarm switch when the housing is forcibly opened, and the alarm sounds in response to the second power supply circuit being turned on. The oxygen sensor is connected to the signal input terminal of the detection switch control circuit, and the output terminal of the detection switch control circuit is connected to the detection switch. The device to be protected has a double-layered housing, consisting of a first housing and a second housing, which divides the internal space of the device into two spaces. The first housing and the second housing are sealed together by a sealing strip, making one of the spaces a sealed space. The sealed space is filled with inert gas, and the oxygen sensor is installed in the sealed space. The circuit board with the anti-tamper circuit is installed in the other space. An oxygen scavenger is provided in the sealed space to keep the oxygen content in the sealed space below a preset value. When the oxygen sensor detects that the oxygen concentration exceeds the preset value, the output terminal of the detection switch control circuit is activated.

2. The anti-tamper circuit according to claim 1 further includes a device power protector and a first power switch, one end of the device power protector is connected to the power input terminal of the device to be protected and the power input terminal of the first power supply, and the other end of the device power protector is connected to the first power supply circuit through the first power switch. When the detection switch detects that the housing is forcibly opened, it turns on the first power switch; the power protector disconnects in response to the current flowing through it exceeding a threshold.

3. The circuit according to claim 2, wherein the alarm switch and the first power switch are transistor switching circuits.

4. The circuit according to claim 3, wherein the second power source is the power supply for the device to be protected, or the first power source, or a battery.

5. The circuit according to claim 1, wherein the first power source is a battery.

6. The circuit according to claim 1, wherein the alarm is a buzzer, an audible and visual alarm, or a detector that emits alarm information.

7. The circuit according to claim 1, wherein the alarm is installed at a location away from the device to be protected.

8. The circuit according to claim 1, wherein the detection switch is a limit switch, micro switch, proximity switch or Hall switch with a built-in normally open switch.

9. The circuit according to claim 1, wherein the detection switch control circuit includes a microcontroller, a transistor circuit, and a signal relay; the signal input terminal of the microcontroller is connected to the oxygen sensor to receive the output signal of the oxygen sensor; the output terminal of the microcontroller is connected to the base of the transistor; the emitter of the transistor is connected to the coil of the signal relay; and a pair of normally open contacts of the signal relay serve as the detection switch.

10. An anti-tamper circuit, installed inside the housing of a device to be protected, wherein the anti-tamper circuit includes a first power supply, a second power supply, a normally open detection switch, an alarm, a first transistor, an oxygen sensor, and a detection switch control circuit, wherein... The first terminal of the detection switch is connected to the first power supply terminal of the first power supply, and the second terminal of the detection switch is connected to the base of the first transistor through a base resistor; the collector of the first transistor is connected to the first terminal of the alarm, and the emitter of the first transistor is connected to the second power supply terminal of the first power supply; the second terminal of the alarm is connected to the power supply terminal of the second power supply. When the housing is forcibly opened, the detection switch closes and the alarm sounds. The oxygen sensor is connected to the signal input terminal of the detection switch control circuit, and the output terminal of the detection switch control circuit is connected to the detection switch. The device to be protected has a double-layered housing, consisting of a first housing and a second housing, which divides the internal space of the device into two spaces. The first housing and the second housing are sealed together by a sealing strip, making one of the spaces a sealed space. The sealed space is filled with inert gas, and the oxygen sensor is installed in the sealed space. The circuit board with the anti-tamper circuit is installed in the other space. An oxygen scavenger is provided in the sealed space to keep the oxygen content in the sealed space below a preset value. When the oxygen sensor detects that the oxygen concentration exceeds the preset value, the output terminal of the detection switch control circuit is activated.

11. The circuit according to claim 10, further comprising a device power protector and a second transistor, wherein a first terminal of the device power protector is connected to the power input terminal of the device to be protected, and a second terminal of the device power protector is connected to the collector of the second transistor; the base of the second transistor is connected to the second terminal of the detection switch through a base resistor, and the emitter of the second transistor is connected to the second power supply terminal of the first power supply; the first power supply terminal of the first power supply is connected to the first terminal of the device power protector through a diode; and the power protector disconnects when the housing is forcibly opened.

12. The circuit according to claim 10, wherein the detection switch control circuit includes a microcontroller, a third transistor circuit, and a signal relay; the input terminal of the microcontroller is connected to the oxygen sensor to receive the output signal of the oxygen sensor; the output terminal of the microcontroller is connected to the base of the third transistor via a base resistor; the emitter of the third transistor is connected to the coil of the signal relay; the collector and emitter of the third transistor are connected to the power supply terminal of the first power supply; and a pair of normally open contacts of the signal relay serve as the detection switch.

Images