Seal tamper detection device, seal tamper detection system, and seal tamper detection method

Abstract

This seal tamper detection device comprises: a first light detection unit that is provided inside a light-shieldable housing and detects light; and a detection unit that detects seal tamper of the housing on the basis of a detection result of the first light detection unit. The first light detection unit detects light in a second wavelength band different from light in a first wavelength band emitted by a light source unit of a maintenance work environment. The detection unit detects seal tamper of the housing when the light in the second wavelength band is detected.

Description

Tampering Detection Device, Tampering Detection System, and Tampering Detection Method

[0001] The present disclosure relates to a tampering detection device, a tampering detection system, and a tampering detection method.

[0002] In a device that holds highly confidential data inside, an anti-tamper mechanism is incorporated to suppress tampering and leakage of the data. For example, Patent Document 1 describes a technique of providing an anti-tamper device that combines a magnet and a Hall element in a housing, and detecting that the housing has been tampered with when the Hall element detects a change in magnetic flux.

[0003] Japanese Patent Application Laid-Open No. 2006-229667

[0004] However, in the conventional method using a magnet, by detecting magnetism from the outside of the housing, the location where the anti-tamper device is provided can be identified. Then, if the housing is opened avoiding the location where the anti-tamper device is provided, or if the housing is opened with a ferromagnetic material approaching the location where the anti-tamper device is provided, the detection of tampering may be invalidated. For example, it may be considered to make the location of the anti-tamper device unidentifiable by a magnetic shield, but since the magnetic shield also blocks radio waves, it cannot be adopted for a device having a wireless communication function.

[0005] An object of the present disclosure is to provide a tampering detection device, a tampering detection system, and a tampering detection method that can make it difficult for a third party to invalidate the detection of unauthorized opening of a housing.

[0006] According to one aspect of the present disclosure, a tampering detection device is provided inside a housing capable of blocking light, and includes a first light detection unit that detects light in a predetermined wavelength band among the light, and a detection unit that detects that the housing has been tampered with based on a detection result of the first light detection unit. The first light detection unit detects light in a second wavelength band different from the light in the first wavelength band emitted by a light source unit in a maintenance work environment, and the detection unit detects that the housing has been tampered with when the light in the second wavelength band is detected.

[0007] According to one aspect of the present disclosure, the tampering detection system comprises the tampering detection device described above and a light source unit that emits light in the first wavelength band into the maintenance work environment.

[0008] According to one aspect of the present disclosure, the tampering detection device is provided inside a light-blocking enclosure and includes a first light detection unit that detects light in a predetermined wavelength band from the light, and a detection unit that detects that the enclosure has been tampered with based on the detection result of the first light detection unit, wherein the first light detection unit detects light in a third wavelength band whose irradiance is less than a predetermined threshold from the wavelength band included in the light emitted from a light source in the maintenance work environment, and the detection unit detects that the enclosure has been tampered with when light in the third wavelength band is detected.

[0009] According to one aspect of the present disclosure, the tampering detection system comprises the tampering detection device described above and a light source unit that emits light with an irradiance in the third wavelength band that is less than a predetermined threshold into the maintenance work environment.

[0010] According to one aspect of the present disclosure, a method for detecting unauthorized opening includes the steps of: a first photodetector provided inside a light-blocking housing detecting light in a predetermined wavelength band from the light; and detecting that the housing has been opened unauthorizedly based on the detection result of the first photodetector, wherein in the step of the first photodetector detecting light, the first photodetector detects light in a second wavelength band that is different from the light in a first wavelength band emitted by a light source in the maintenance work environment, and in the step of detecting that the housing has been opened unauthorizedly, if light in the second wavelength band is detected, the housing has been opened unauthorizedly.

[0011] According to one aspect of the present disclosure, a method for detecting unauthorized opening includes the steps of: a first photodetector provided inside a light-blocking housing detecting light in a predetermined wavelength band from the light; and detecting that the housing has been opened unauthorizedly based on the detection result of the first photodetector, wherein in the step of the first photodetector detecting light, the first photodetector detects light in a third wavelength band whose irradiance is less than a predetermined threshold from the wavelength band included in the light emitted from a light source in the maintenance work environment, and in the step of detecting that the housing has been opened unauthorizedly, if light in the third wavelength band is detected, the housing has been opened unauthorizedly.

[0012] According to the above embodiment, it is possible to make it difficult for a third party to disable the detection of unauthorized opening of the enclosure.

[0013] This is a first diagram showing the overall configuration of the tampering detection system according to the first embodiment. This is a second diagram showing the overall configuration of the tampering detection system according to the first embodiment. This is a third diagram showing the overall configuration of the tampering detection system according to the first embodiment. This is a first diagram showing the overall configuration of the tampering detection system according to a modified example of the first embodiment. This is a second diagram showing the overall configuration of the tampering detection system according to a modified example of the first embodiment. This is a diagram showing an example of the emission wavelength characteristics of the light source according to the second embodiment. This is a first diagram showing the functional configuration of the tampering detection device according to the third embodiment. This is a diagram showing an example of the emission wavelength characteristics of the light source according to the third embodiment. This is a second diagram showing the functional configuration of the tampering detection device according to the third embodiment. This is a first diagram for explaining the function of the tampering detection device according to the third embodiment. This is a second diagram for explaining the function of the tampering detection device according to the third embodiment. This is a third diagram for explaining the function of the tampering detection device according to the third embodiment.

[0014] <First Embodiment> The first embodiment will be described in detail below with reference to Figures 1 to 3.

[0015] (Overall Configuration of the Tampering Detection System) Figure 1 is a first diagram showing the overall configuration of the tampering detection system according to the first embodiment. As shown in Figure 1, the tampering detection system 100 comprises a light source unit 2 provided in the maintenance work environment and a tampering detection device 3 that detects tampering with the housing 11 of the device 1.

[0016] The maintenance work environment is a space such as a room where maintenance work on the device 1 is performed. The light source unit 2 has a light source 21. The light source 21 is an illumination that emits light such as visible light and near-infrared light into the maintenance work environment. In this embodiment, the light source 21 emits light L in a specific wavelength band (first wavelength band) from among the wavelength bands of visible light and near-infrared light.

[0017] The housing 11 of the device 1 has a cover 12 that can be opened and closed. Normally, the cover 12 is closed to block light from entering the inside of the housing 11. At this time, the housing 11 blocks not only visible light but also invisible light such as near-infrared light. In addition, the cover 12 is opened during maintenance work to repair the device 1.

[0018] The unauthorized opening detection device 3 detects that the housing 11 of the device 1 has been opened illegally.

[0019] (Functional configuration of the tampering detection device) As shown in Figure 1, the tampering detection device 3 is installed inside the housing 11 of the device 1. The tampering detection device 3 comprises a first optical sensor 31 and a detection unit 32.

[0020] The first light sensor 31 is provided inside the housing 11. The first light sensor 31 is an example of a first light detection unit, and when the housing 11 is opened, it detects light such as visible light and near-infrared light emitted from lighting or the like. In this embodiment, the first light sensor 31 detects light in a second wavelength band that is different from the light L in a first wavelength band emitted by the light source unit 2. For example, the light L in the first wavelength band is light in a part of the wavelength band within the range from visible light to near-infrared light, and the light in the second wavelength band is light in wavelength bands other than the first wavelength band, including visible light and invisible light (ultraviolet light and infrared light).

[0021] The first light sensor 31 includes a photodiode 311, a conversion circuit 312, and a comparator 313. The photodiode 311 generates a current corresponding to the amount of incident light. The current generated by the photodiode 311 is converted into a voltage V1 by the conversion circuit 312, which is composed of an operational amplifier and a resistor, and input to the comparator 313. The comparator 313 compares the voltage V1 corresponding to the amount of incident light on the photodiode 311 with a reference voltage Vref and outputs a signal Vout indicating whether or not light has been detected. The comparator 313 outputs an H-level signal Vout indicating that light has been detected when the voltage V1 is equal to or greater than the reference voltage Vref, and an L-level signal Vout when the voltage V1 is less than the reference voltage Vref.

[0022] The photodiode 311 used is one that is sensitive to the second wavelength band. Figure 2 is a second diagram showing the overall configuration of the tamper-evident detection system according to the first embodiment. As shown in Figure 2, a filter 314 may be provided so as to cover the light-receiving surface of the photodiode 311. The filter 314 blocks light in the first wavelength band. When a filter 314 is provided, there are no restrictions on the spectral sensitivity characteristics of the photodiode 311, and it may be sensitive to multiple wavelength bands, including the second wavelength band.

[0023] The detection unit 32 detects that the housing 11 has been illegally opened based on the detection result of the first optical sensor 31 (output signal of the comparator 313). In this embodiment, the detection unit 32 detects that the housing 11 has been illegally opened when the first optical sensor 31 detects light in the second wavelength band. The detection result of the detection unit 32 is notified, for example, to the control unit of the device 1. When the control unit of the device 1 receives notification of illegal opening, it performs predetermined processing such as recording an illegal opening log and erasing security information.

[0024] Figure 3 is a third diagram showing the overall configuration of the tampering detection system according to the first embodiment. The tampering detection device 3 is not limited to a configuration combining circuits as shown in Figures 1 and 2, but may also have a configuration as shown in Figure 3. That is, as shown in Figure 3, the tampering detection device 3 may have an A / D converter 315 instead of the comparator 313 in Figures 1 and 2. In this case, the first light sensor 31 converts the current generated by the photodiode 311 into a voltage using a conversion circuit 312, and then converts it into a digital signal using the A / D converter 315 and inputs it to the processor. The processor performs its function as a detection unit 32 according to a predetermined program. That is, the detection unit 32 compares the voltage input from the first light sensor 31 with a reference voltage to determine whether the first light sensor 31 has detected light in the second wavelength band.

[0025] (Operation of the Tampering Detection Device) Next, the operation of the tampering detection device 3 will be explained. The combination of the color of light to be used in the maintenance work environment (first wavelength band) and the color of light detected by the tampering detection device 3 (second wavelength band) is predetermined by the manufacturer of the tampering detection device 3. For example, the light source unit 2 is set to emit red light (first wavelength band of 600 nm or more), and the first light sensor 31 is set to detect blue light (second wavelength band of 500 nm or less). Note that this combination is just one example. The first and second wavelength bands may be arbitrarily set to different wavelength bands, and may include not only visible light but also near-infrared light, etc. In the example above, the light of the first wavelength band emitted by the light source unit 2 was set to red visible light, but it is not limited to this, and the light of the first wavelength band may include infrared light. Also, the light of the second wavelength band detected by the first light sensor 31 was set to blue visible light, but it is not limited to this, and the light of the second wavelength band may include ultraviolet light. Furthermore, the combination of the first wavelength band and the second wavelength band may be changed for each group of device 1, for example. The light color (first wavelength band) to be used in the maintenance work environment is communicated in advance by the manufacturer to the maintenance worker of device 1. If the combination is changed for each group, a correspondence table between information for identifying the group (e.g., lot number, markings on the housing 11, etc.) and the first wavelength band is communicated to the maintenance worker.

[0026] Based on information provided by the manufacturer, the maintenance worker installs lighting that emits only light L in the first wavelength band as the light source unit 2 of the maintenance work environment. The maintenance work environment is also shielded from sunlight or other room lighting through windows, etc. As described above, the first light sensor 31 of the tampering detection device 3 is sensitive to the second wavelength band but not to the first wavelength band. Therefore, if the housing 11 is opened in the maintenance work environment, the first light sensor 31 will not detect light, and the detection unit 32 will not detect tampering. For this reason, in the maintenance work environment, the maintenance worker can perform maintenance work on the device 1 without causing the device 1 to execute processing (such as erasing security information) when tampering is detected.

[0027] On the other hand, a third party cannot know the conditions under which unauthorized opening is not detected (using light in the first wavelength band as the light source). A third party attempts to open the casing 11 in an environment where sunlight or normal lighting (incandescent bulb, fluorescent lamp, etc.) is emitted. The light emitted by sunlight or normal lighting includes light in the second wavelength band. Therefore, the first light sensor 31 detects that it has received light in the second wavelength band, and the detection unit 32 detects unauthorized opening. In this case, the device 1 executes the processing for when unauthorized opening is detected. In this way, the unauthorized opening detection device 3 makes it difficult for a third party to disable the detection of unauthorized opening. As a result, the tampering with or leakage of security information of the device 1 can be more reliably suppressed.

[0028] (Effects) As described above, the unauthorized opening detection device 3 according to this embodiment includes a first light sensor 31 that detects light and is installed inside a light-blocking housing 11, and a detection unit 32 that detects that the housing 11 has been opened illegally based on the detection result of the first light sensor 31. The first light sensor 31 detects light in a second wavelength band that is different from the light L in the first wavelength band emitted by the light source unit 2 of the maintenance work environment, and the detection unit 32 detects that the housing 11 has been opened illegally when light in the second wavelength band is detected.

[0029] Unlike conventional methods using magnets, the tamper-tamper detection device 3 of this embodiment uses a first optical sensor 31 (photodiode 311) to detect tampering, making it difficult for a third party to identify the location where the tamper-tamper detection device 3 is installed from outside the housing 11. Therefore, the tamper-tamper detection device 3 makes it difficult for a third party to bypass the detection of tampering by avoiding the location of the first optical sensor 31 when opening the housing. Furthermore, maintenance workers are instructed in advance by the manufacturer to use a first wavelength band of light in the maintenance work environment. For this reason, in the maintenance work environment, a light source unit 2 that emits only light in the first wavelength band is used. Consequently, if the housing 11 is opened in the maintenance work environment, the tamper-tamper detection device 3 will not detect light in the second wavelength band. In other words, in the maintenance work environment, the detection of tampering is disabled. Therefore, maintenance workers can perform maintenance work on the device 1 without detecting tampering. On the other hand, a third party cannot know the first wavelength band of light used in the maintenance work environment or the second wavelength band of light detected by the first optical sensor 31 of the tamper-tamper detection device 3. Therefore, they will open the casing 11 in an environment where sunlight or normal lighting is emitted. In this case, the tamper-tamper detection device 3 will detect the light in the second wavelength band included in normal lighting, and will be able to detect that the casing 11 has been opened illegally. In other words, the tamper-tamper detection device 3 can make it difficult for a third party to disable the detection of illegal opening.

[0030] Furthermore, the first light sensor 31 has a photodiode 311 that is sensitive to the second wavelength band, or a photodiode 311 covered with a filter 314 that blocks light in the first wavelength band.

[0031] In this way, the tamper-evident detection device 3 can accurately detect whether or not the designated light source unit 2 is being used during maintenance work.

[0032] Furthermore, the tampering detection system 100 includes the tampering detection device 3 described above and a light source unit 2 that emits light L into the maintenance work environment. The light source unit 2 has a light source 21 that emits only light L in the first wavelength band.

[0033] In this way, the tampering detection system 100 can perform maintenance work in a maintenance environment with the tampering detection function of the tampering detection device 3 disabled. On the other hand, a third party cannot know the first wavelength band of light used in the maintenance environment or the second wavelength band of light detected by the first optical sensor 31 of the tampering detection device 3. Therefore, it is difficult for a third party to disable the detection of tampering.

[0034] Furthermore, as described above, the combination of the first wavelength band and the second wavelength band may be changed for each group of device 1. In this way, maintenance workers can disable the detection of unauthorized opening by using the appropriate light source unit 2 according to the group, based on the combination specified in advance by the manufacturer, and perform maintenance work. On the other hand, it is difficult for a third party who does not know the combination for each group to disable unauthorized opening. Even if a third party is able to disable the detection of unauthorized opening on device 1, which is the light source used by that third party, they will not be able to disable the detection of unauthorized opening on device 1 in a different group, even if they use the same light source. Therefore, the alteration or leakage of security information due to unauthorized opening can be minimized.

[0035] <Modification of the First Embodiment> Figure 4 is a first diagram showing the overall configuration of the tamper-evident detection system according to a modification of the first embodiment. Figure 5 is a second diagram showing the overall configuration of the tamper-evident detection system according to a modification of the first embodiment. As shown in the modifications in Figures 4 and 5, the light source unit 2 may consist of a light source 21 and a filter 22 installed between the light source 21 and the device 1. Unlike the first embodiment, the light source 21 in this modification does not emit light only in a specific wavelength band, but a light source with broad wavelength characteristics may be used. For example, the light source 21 may be the sun or a halogen lamp. The filter 22 blocks only light in the second wavelength band and transmits light in other wavelength bands (first wavelength band). When the light source 21 is the sun, for example, the filter 22 may be installed in a window that takes in sunlight.

[0036] Furthermore, the first optical sensor 31 of the tamper-evident device 3 may consist only of a photodiode 311 that is sensitive to the second wavelength band, as in the example in Figure 4, or it may consist of a photodiode 311 and a filter 314 that transmits only light in the second wavelength band, as in the example in Figure 5.

[0037] In this modified example, as in Figure 3 of the first embodiment, the first optical sensor 31 may have an A / D converter 315 instead of a comparator 313, and the detection unit 32 may compare the voltage input from the first optical sensor 31 with a reference voltage to determine whether or not the first optical sensor 31 has detected light in the second wavelength band.

[0038] In this way, the light source unit 2 can emit only light L in the first wavelength band without using a special light source. Furthermore, by blocking the light in the second wavelength band emitted by the light source unit 2 in the maintenance work environment and combining this with the first light sensor 31 detecting only light in the second wavelength band, false detection of unauthorized opening can be suppressed in the maintenance work environment.

[0039] <Second Embodiment> The second embodiment will be described below with reference to Figure 6. Note that components of the second embodiment that are the same as those of the first embodiment will be described using the same reference numerals as in the first embodiment.

[0040] In the first embodiment, an example was described in which the light source unit 2 of the maintenance work environment emits only light L in the first wavelength band. However, in this case, the lighting of the maintenance work environment becomes a specific hue. This may make it difficult to distinguish the color of the cables of the device 1, potentially worsening work efficiency. For this reason, in this embodiment, a white light source other than a heat-generating type such as an incandescent bulb or halogen lamp (e.g., fluorescent lamp, LED lighting, etc.) is used as the light source 21 of the light source unit 2. The light source 21 used in the maintenance work environment is specified in advance by the manufacturer of the tamper-evident device 3. Here, an example in which the light source 21 is LED lighting will be described.

[0041] Furthermore, in the modified tampering detection device 3, the light detected by the first optical sensor 31 is determined based on the emission wavelength characteristics of the light source 21.

[0042] Figure 6 shows an example of the emission wavelength characteristics of a light source according to the second embodiment. Figure 6 illustrates the emission wavelength characteristics of LED lighting. In Figure 6, the horizontal axis represents wavelength, and the vertical axis represents irradiance for each wavelength. As shown in Figure 6, LED lighting has different irradiance depending on the wavelength. Utilizing these emission wavelength characteristics of LED lighting, the first light sensor 31 of this embodiment detects light in a third wavelength band, where the irradiance is less than a predetermined threshold, among the wavelength bands of light emitted by the light source 21 (LED lighting). If there are multiple wavelength bands where the irradiance is less than a predetermined threshold, for example, a wavelength band where the irradiance is relatively high in another light source (such as the sun or a heat-generating white light source) is selected. In the example in Figure 6, wavelength band B1 is set as the third wavelength band. In this case, the photodiode 311 of the first light sensor 31 is one that is sensitive to the third wavelength band (wavelength band B1). Alternatively, a filter 314 that transmits only light in the third wavelength band may be provided. If a filter 314 is provided, the photodiode 311 may be sensitive to multiple wavelength bands, including a third wavelength band. The detection unit 32 detects that the housing 11 has been illegally opened when the first light sensor 31 detects light in the third wavelength band. Note that the third wavelength band is not limited to the visible light wavelength band, but may also include ultraviolet and infrared light wavelength bands.

[0043] In this way, the tampering detection device 3 can disable the detection of tampering during maintenance work by using a pre-specified light source 21. Furthermore, since the light source 21 can be a white light source such as an LED light, work efficiency can be improved. Moreover, unlike the modification of the first embodiment, the effort of installing a filter 22 in the light source unit 2 can be eliminated. On the other hand, even if a third party knows that a white light source is being used in the maintenance work environment, they cannot know the emission wavelength characteristics of the light source 21. In that case, if a third party opens the housing 11 thinking that tampering will not be detected with a white light source, and a white light source with different emission wavelength characteristics than the light source 21 is used, the tampering detection device 3 can correctly detect that it has been tampered with.

[0044] <Third Embodiment> The third embodiment will be described below with reference to FIGS. 7 to 12. Among the configurations of the third embodiment, those that are the same as the configurations of the above-described embodiments will be described using the same reference numerals as the above-described embodiments.

[0045] In the second embodiment, the third wavelength band detected by the first optical sensor 31 is set based on the emission wavelength characteristics of the light source 21 (such as LED illumination). However, depending on the environment where the tamper detection device 3 is placed, such as when the distance between the light source 21 and the device 1 is short or when the influence of temperature change occurs, the first optical sensor 31 may detect light in the third wavelength band, and there is a possibility that tampering may be erroneously detected during maintenance work. Therefore, the tamper detection device 3 of the present embodiment is configured to suppress such false detections.

[0046] FIG. 7 is a first diagram showing the functional configuration of the tamper detection device according to the third embodiment. FIG. 8 is a diagram showing an example of the emission wavelength characteristics of the light source according to the third embodiment. As shown in FIG. 7, the tamper detection device 3 includes a second optical sensor 33 in addition to the first optical sensor 31. Similar to the second embodiment, the first optical sensor 31 detects light in the third wavelength band where the irradiance of the light source 21 is small. The second optical sensor 33 is an example of a second light detection unit, and detects light in the fourth wavelength band where the irradiance of the light source 21 is the largest. FIG. 8 illustrates the emission wavelength characteristics of the same LED illumination as in FIG. 6. In the example of FIG. 8, the wavelength band B2 is set as the fourth wavelength band. Further, for example, when an ultraviolet light sensor is used for the first optical sensor 31 (that is, when the third wavelength band is the wavelength band of ultraviolet light), illumination with less ultraviolet light (for example, LED illumination) is used for the light source 21. By doing so, it is possible to easily detect tampering when the housing 11 is opened in an environment where illumination with more ultraviolet light (such as a halogen lamp) than the light source unit 2 such as LED illumination is emitted. Even when a filter 22 is used for the light source unit 2 as in the modification of the first embodiment, since ultraviolet light, which is invisible light, may be blocked, the influence on the hue is small. Note that the fourth wavelength band is not limited to the wavelength band of visible light and may include the wavelength bands of ultraviolet light and infrared light.

[0047] The second optical sensor 33 includes a photodiode 331, a conversion circuit 332, and a comparator 333. The photodiode 331 used has sensitivity in the fourth wavelength band (wavelength band B2). The conversion circuit 332 and the comparator 333 have the same functional configuration as the conversion circuit 312 and the comparator 313 of the first optical sensor 31. The first optical sensor 31 compares the voltage V3 corresponding to the amount of incident light on the photodiode 311 with the reference voltage Vref1 and outputs a signal S3 indicating whether or not light has been detected. The second optical sensor 33 compares the voltage V4 corresponding to the amount of incident light on the photodiode 331 with the reference voltage Vref2 and outputs a signal S4 indicating whether or not light has been detected. The first optical sensor 31 detects light that the light source 21 in the maintenance work environment should not emit, and the second optical sensor 33 detects light that the light source 21 in the maintenance work environment should emit. Therefore, for example, the reference voltage Vref1 that is the light detection threshold of the first optical sensor 31 is set to a value smaller than the reference voltage Vref2 that is the light detection threshold of the second optical sensor 33. Also, the values of the reference voltage Vref1 of the comparator 313 and the reference voltage Vref2 of the comparator 333 can be arbitrarily changed by changing the constants of the resistors that the comparators 313 and 333 have.

[0048] FIG. 9 is a second diagram showing the functional configuration of the tamper detection device according to the third embodiment. As shown in FIG. 9, the second optical sensor 33 may have a filter 334 that transmits only light in the fourth wavelength band. In this case, the photodiode 331 may have sensitivity in a plurality of wavelength bands including the fourth wavelength band.

[0049] The detection unit 32 detects unauthorized opening of the housing 11 based on the detection results of the first optical sensor 31 and the second optical sensor 33. For example, when the first optical sensor 31 detects light in the third wavelength band and the second optical sensor 33 does not detect light in the fourth wavelength band, the detection unit 32 detects that a light source other than the designated light source 21 has been used, that is, the housing 11 has been illegally opened. Also, when both the first optical sensor 31 and the second optical sensor 33 detect light and the amount of light in the third wavelength band is significantly large, the detection unit 32 detects that a light source other than the designated light source 21 has been used, that is, the housing 11 has been illegally opened.

[0050] The specific functional configuration of the detection unit 32 will now be described. As shown in Figures 7 and 9, the detection unit 32 has a plurality of logic circuits 321, 324, and 325, an amplification circuit 322, and a comparator 323. Logic circuits 321 and 324 are AND gates, and logic circuit 325 is an XOR gate. Details of logic circuits 321, 324, and 325 will be described later.

[0051] The amplification circuit 322 amplifies the voltage V3, which corresponds to the amount of light in the third wavelength band detected by the first light sensor 31, by a factor of k. The amplified value is used in the subsequent comparator 323.

[0052] The comparator 323 compares the light intensity in the third and fourth wavelength bands based on the voltage V3 (k*V3) multiplied by k by the amplification circuit 322 and the voltage V4 corresponding to the light intensity in the fourth wavelength band detected by the second photosensor 33. Here, the voltages V3 and V4 output from the first photosensor 31 and the second photosensor 33, respectively, are used as values ​​representing the light intensity. The comparator 323 outputs a low-level signal Vcomp if the value obtained by multiplying the light intensity V3 in the third wavelength band by k (k*V3) is greater than or equal to the light intensity V4 in the fourth wavelength band (k*V3 ≥ V4). On the other hand, if the value obtained by multiplying the light intensity V3 in the third wavelength band by k (k*V3) is less than the light intensity V4 in the fourth wavelength band (k*V3 < V4), it outputs a high-level signal Vcomp.

[0053] Figure 10 is the first diagram illustrating the function of the tamper-evident detection device according to the third embodiment. Figure 10 is an example of the truth table of the logic circuit 321 (AND gate). The logic circuit 321 takes as input a signal S3 indicating whether or not the first optical sensor 31 has detected light in the third wavelength band, and a signal S4 indicating whether or not the second optical sensor 33 has detected light in the fourth wavelength band, and outputs a signal OUT1. Signals S3 and S4 are H level when light is detected and L level when no light is detected, respectively. In the following description, the H level signal will also be referred to as "H" and the L level signal as "L".

[0054] If no light is detected in either the third or fourth wavelength band (S3 = L and S4 = L), the output signal OUT1 of the logic circuit 321 is "L". In this case, it is assumed that the enclosure 11 is unopened.

[0055] If no light in the third wavelength band is detected, and light in the fourth wavelength band is detected (S3 = L, S4 = H), the output signal OUT1 of the logic circuit 321 is "L". In this case, it is assumed that the designated light source 21 is being used and that there has been no unauthorized opening.

[0056] If light in the third wavelength band is detected and light in the fourth wavelength band is not detected (S3 = H, S4 = L), the output signal OUT1 of the logic circuit 321 is "L". However, in this case, the designated light source 21 is not being used and is assumed to be tampered with, so the subsequent logic circuit detects the tampering.

[0057] If light from both the third and fourth wavelength bands is detected (S3 = H and S4 = H), the output signal OUT1 of the logic circuit 321 is "H". However, in this case, it cannot be determined that the package has been tampered with. As illustrated in Figure 8, even if the designated light source 21 is used, the light L emitted from the light source 21 does not necessarily contain no light from the third wavelength band at all (i.e., the irradiance is zero). For example, if the distance between the light source 21 and the device 1 is short, the amount of light incident on the first light sensor 31 (photodiode 311) increases, and the value of the voltage V3 may become greater than the reference voltage Vref. Therefore, when light from both the third and fourth wavelength bands is detected in this way, the comparator 323 performs a light intensity determination.

[0058] Figure 11 is a second diagram illustrating the function of the tamper-evident detection device according to the third embodiment. Figure 11 is an example of the truth table of the logic circuit 324 (AND gate). The logic circuit 324 takes the output signal OUT1 of the logic circuit 321 and the output Vcomp of the comparator 323 as inputs and outputs the signal OUT2.

[0059] If the output signal OUT1 of logic circuit 321 is "L" and the output Vcomp of comparator 323 is "L", then the output signal OUT2 of logic circuit 324 is "L". At this point, it is unknown whether or not the enclosure 11 has been illegally opened. Therefore, if the output signal OUT2 is "L", the logic circuit 325 described later will detect whether or not it has been illegally opened based on whether the output signal S3 is "H" or "L".

[0060] When the output signal OUT1 of logic circuit 321 is "L" and the output Vcomp of comparator 323 is "H", the output signal OUT2 of logic circuit 324 is "L". In this case, since no light in the third wavelength band was detected (S3 = L) and light in the fourth wavelength band was detected (S4 = H), it is assumed that the designated light source 21 was used and that there was no unauthorized opening.

[0061] When the output signal OUT1 of logic circuit 321 is "H" and the output Vcomp of comparator 323 is "L", the output signal OUT2 of logic circuit 324 is "L". In this case, light from both the third and fourth wavelength bands is detected (S3 = H and S4 = H), and the amount of light in the third wavelength band was significantly larger (k * V3 ≥ V1). Therefore, it is assumed that the designated light source 21 was not used and that the device was tampered with.

[0062] When the output signal OUT1 of logic circuit 321 is "H" and the output Vcomp of comparator 323 is "H", then the output signal OUT2 of logic circuit 324 is "H". In this case, although light from both the third and fourth wavelength bands was detected (S3 = H and S4 = H), the amount of light in the third wavelength band was small (k * V3 < V1), so it is assumed that the designated light source 21 was used and that there was no tampering.

[0063] Figure 12 is a third diagram illustrating the function of the tampering detection device according to the third embodiment. Figure 12 is an example of a truth table for the logic circuit 325 (XOR gate). The logic circuit 325 takes the output signal OUT2 of the logic circuit 324 and the output signal S3 of the first optical sensor 31 as inputs and outputs the signal OUT3. When the signal OUT3 is "H", it indicates that tampering has been detected, and when it is "L", it indicates that tampering has not been detected.

[0064] When the output signal OUT2 of logic circuit 324 is "L" and signal S3 is "L", the output signal OUT3 of logic circuit 325 is "L" (no unauthorized opening detected). This applies to cases where the enclosure 11 has not been opened (S3=L and S4=L), or where the specified light source 21 has been used (S3=L and S4=H, or S3=H and S4=H and k*V3<V4).

[0065] If the output signal OUT2 of logic circuit 324 is "L" and signal S3 is "H", then the output signal OUT3 of logic circuit 325 is "H" (unauthorized tampering detected). This applies to cases where the designated light source 21 is not being used (S3=H and S4=L, or S3=H and S4=H and k*V3≧V4).

[0066] There is no case where the output signal OUT2 of logic circuit 324 is "H" and signal S3 is "L". This is because the output signal OUT2 of logic circuit 324 is "H" only when both signals S3 and S4 are "H".

[0067] When the output signal OUT2 of logic circuit 324 is "H" and signal S3 is "H", the output signal OUT3 of logic circuit 325 is "L" (no unauthorized opening detected). This applies to the case where the specified light source 21 is used (S3=H and S4=H and k*V3<V4).

[0068] In this embodiment, the logic circuit 325 is an XOR circuit, and an example has been described in which it outputs the output signal OUT3 as shown in Figure 12, but it is not limited to this. If we consider that the detection result of the first optical sensor 31 is the main factor in detecting unauthorized opening, then if the output of the first optical sensor 31 is small (signal S3 = L), then it is considered that it is not unauthorized opening (output signal OUT3 = L), regardless of the output of the output signal OUT2. On the other hand, when the signal S3 = H, it is possible that the first optical sensor 31 detected light due to unauthorized opening, but it is also possible that the first optical sensor 31 may detect light even though the specified light source 21 is being used, such as when the distance to the light source 21 is short or when the light emission intensity of the light source 21 changes due to temperature changes in the maintenance work environment. Therefore, when the signal S3 = H, the decision is made based on the output signal OUT2. In other words, if the output signal OUT2 is L (k*V3 ≥ V4; the light intensity in the third wavelength band is high), it is considered an unauthorized opening (output signal OUT3 = H), and if the output signal OUT2 is H (k*V3 < V4; the light intensity in the third wavelength band is low), it is not considered an unauthorized opening (output signal OUT3 = L). In Figure 12, it is assumed that the case where output signal OUT2 = H and signal S3 = L does not exist, but in other embodiments, following the above considerations, when output signal OUT2 = H and signal S3 = L, output signal OUT3 may be set to "L". In this case, logic circuit 325 may be changed to an appropriate circuit instead of an XOR circuit.

[0069] Furthermore, similar to the first embodiment, the detection unit 32 may not be composed of a circuit, but rather a functional unit executed by a processor according to a program. That is, the first optical sensor 31 has an A / D converter 315 instead of a comparator 313. Similarly, the second optical sensor 33 also has an A / D converter (not shown) instead of a comparator 333. The detection unit 32 then performs the following processes according to a predetermined program: comparing the voltage V3 input from the first optical sensor 31 with a reference voltage Vref1 (processing corresponding to the comparator 313), comparing the voltage V4 input from the second optical sensor 33 with a reference voltage Vref2 (processing corresponding to the comparator 333), outputting an output signal OUT1 according to the combination of signals S3 and S4 (processing corresponding to the logic circuit 321), amplifying the voltage V3 (processing corresponding to the amplification circuit 322), and comparing the amplified voltage V3 with the voltage V4 to output a signal Vcomp (processing corresponding to the comparator 323). The system performs a process that outputs an output signal OUT2 according to the combination of output signal OUT1 and Vcomp (a process corresponding to the logic circuit), and a process that determines whether or not the package has been tampered with based on output signal OUT2 and signal S3 (a process corresponding to the logic circuit 325).

[0070] As described above, the tamper-opening detection device 3 of this embodiment includes a first optical sensor 31 and a second optical sensor 33. The first optical sensor 31 detects light in the third wavelength band, which has low irradiance, from the light emitted from the designated light source 21. The second optical sensor 33 detects light in the fourth wavelength band, which has the highest irradiance, from the light emitted from the light source 21. The detection unit 32 detects that the housing 11 has been tampered with when it detects light in the third wavelength band and does not detect light in the fourth wavelength band.

[0071] In this way, the tampering detection device 3 can determine whether it detected light from the designated light source 21 or light from another light source, taking into account the wavelength characteristics of the designated light source 21, and can detect with greater accuracy whether or not the package has been tampered with.

[0072] Furthermore, the detection unit 32 detects that the housing 11 has been illegally opened when both the first light sensor 31 and the second light sensor 33 detect light, and the value k*V3 obtained by multiplying the light intensity in the third wavelength band by k is greater than the light intensity V4 in the fourth wavelength band.

[0073] In this way, the tampering detection device 3 can compare the light intensity in the third wavelength band and the fourth wavelength band to determine whether the light in the third wavelength band was detected because the designated light source 21 was not being used, or whether the light in the third wavelength band was detected due to the influence of the environment in which the tampering detection device 3 is placed, such as the distance to the light source 21 being short or the light intensity of the light source 21 changing due to temperature changes in the maintenance work environment. As a result, when the designated light source 21 is being used in the maintenance work environment, false detection of tampering can be reliably suppressed regardless of the environmental conditions in which the tampering detection device 3 is placed, including the distance between the light source 21 and the device 1. On the other hand, if a third party uses a light source other than the designated light source 21, it can be correctly detected as tampering.

[0074] <Other Embodiments> Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to that described above, and various design changes can be made.

[0075] <Note> The above-described embodiment can be understood, for example, as follows.

[0076] (1) According to the first embodiment, the tampering detection device 3 is provided inside the light-blocking housing 11 and includes a first light detection unit 31 that detects light in a predetermined wavelength band and a detection unit 32 that detects that the housing 11 has been tampered with based on the detection result of the first light detection unit 31. The first light detection unit 31 detects light in a second wavelength band that is different from the light in a first wavelength band emitted by the light source unit 2 of the maintenance work environment, and the detection unit 32 detects that the housing 11 has been tampered with when light in the second wavelength band is detected.

[0077] Unlike conventional methods using magnets, the tampering detection device 3 uses a first light detection unit 31 to detect tampering, making it difficult for a third party to identify the location of the tampering detection device 3 from outside the housing 11. Therefore, the tampering detection device 3 makes it difficult for a third party to bypass the detection of tampering by avoiding the location of the first light detection unit 31 when opening the housing. Furthermore, in the maintenance work environment, a light source unit 2 that emits only light in a predetermined first wavelength band is used. In this case, if the housing 11 is opened in the maintenance work environment, the tampering detection device 3 will not detect light in the second wavelength band. In other words, in the maintenance work environment, the detection of tampering is disabled. As a result, maintenance workers can perform maintenance work on the device 1 without detecting tampering. On the other hand, a third party cannot know the first wavelength band of light used in the maintenance work environment or the second wavelength band of light detected by the first light detection unit 31 of the tampering detection device 3, so they will open the housing 11 in an environment where sunlight or normal lighting is emitted. As a result, the tampering detection device 3 detects light in the second wavelength band, which is included in normal lighting, and can detect that the casing 11 has been opened illegally. In other words, the tampering detection device 3 makes it difficult for a third party to disable the detection of tampering.

[0078] (2) According to the second embodiment, in the tamper-evident device 3 according to the first embodiment, the first light detection unit 31 has a photodiode 311 that is sensitive to the second wavelength band, or a photodiode 311 covered with a filter 314 that blocks light in the first wavelength band.

[0079] In this way, the tamper-evident detection device 3 can accurately detect whether or not the designated light source unit 2 is being used during maintenance work.

[0080] (3) According to the third embodiment, the tampering detection device 3 is provided inside the light-blocking housing 11 and includes a first light detection unit 31 that detects light in a predetermined wavelength band and a detection unit 32 that detects that the housing 11 has been tampered with based on the detection result of the first light detection unit 31. The first light detection unit 31 detects light in a third wavelength band whose irradiance is less than a predetermined threshold among the wavelength bands included in the light emitted from the light source unit 2 of the maintenance work environment, and the detection unit 32 detects that the housing 11 has been tampered with when light in the third wavelength band is detected.

[0081] In this way, the tamper-tamper detection device 3 can disable the detection of tampering during maintenance work by using a pre-specified light source unit 2. Furthermore, since the light source 21 can be a white light source such as LED lighting, work efficiency can be improved. On the other hand, even if a third party knows that a white light source is being used in the maintenance work environment, they cannot know the emission wavelength characteristics of the light source 21. In that case, if a third party opens the housing 11 thinking that tampering will not be detected with a white light source, and a white light source with different emission wavelength characteristics than the light source unit 2 is used, the tamper-tamper detection device 3 can correctly detect that it has been opened illegally.

[0082] (4) According to the fourth embodiment, in the tamper-evident device 3 according to the third embodiment, the first light detection unit 31 has a photodiode 311 that is sensitive to the third wavelength band, or a photodiode 311 covered with a filter 314 that transmits only light in the third wavelength band.

[0083] In this way, the tamper-evident detection device 3 can accurately detect whether or not the designated light source unit 2 is being used during maintenance work.

[0084] (5) According to the fifth embodiment, the unauthorized opening detection device 3 according to the third or fourth embodiment further comprises a second light detection unit 33 provided inside the housing 11, which detects light in the fourth wavelength band with the greatest irradiance among the wavelength bands included in the light emitted from the light source unit 2 of the maintenance work environment, and the detection unit 32 detects that the housing 11 has been opened illegally when light in the third wavelength band is detected and light in the fourth wavelength band is not detected.

[0085] In this way, the tampering detection device 3 can determine whether it detected light from the designated light source 2 or light from another light source, taking into account the wavelength characteristics of the light source 2, and can detect with greater accuracy whether or not the package has been tampered with.

[0086] (6) According to the sixth aspect, in the unauthorized opening detection device 3 according to the fifth aspect, the detection unit 32 detects that the housing 11 has been opened illegally when light in both the third wavelength band and the fourth wavelength band is detected, and the value obtained by multiplying the detected light in the third wavelength band by a predetermined factor is greater than the detected light in the fourth wavelength band.

[0087] In this way, when the tampering detection device 3 is using the designated light source 21 in the maintenance work environment, it can reliably suppress false detection of tampering regardless of the environmental conditions in which the tampering detection device 3 is placed, including the distance between the light source unit 2 and the device 1. On the other hand, if a third party uses a light source other than the designated light source 21, it can correctly detect that it has been tampered with.

[0088] (7) According to the seventh embodiment, in the tamper-evident device 3 according to the sixth or seventh embodiment, the second photodetector 33 has a photodiode 331 that is sensitive to the fourth wavelength band, or a photodiode 331 covered with a filter 334 that transmits only light in the fourth wavelength band.

[0089] In this way, the tamper-evident detection device 3 can accurately detect whether or not the designated light source unit 2 is being used during maintenance work.

[0090] (8) According to the eighth aspect, the tampering detection system 100 comprises a tampering detection device 3 according to the first or second aspect, and a light source unit 2 that emits light in the first wavelength band into the maintenance work environment.

[0091] In this way, the tampering detection system 100 can perform maintenance work in a maintenance environment with the tampering detection function of the tampering detection device 3 disabled. On the other hand, a third party cannot know the first wavelength band of light used in the maintenance environment or the second wavelength band of light detected by the first light detection unit 31 of the tampering detection device 3. Therefore, it is difficult for a third party to disable the detection of tampering.

[0092] (9) According to the ninth aspect, the tampering detection system 100 comprises a tampering detection device 3 according to any one of the third to seventh aspects, and a light source unit 2 that emits light with an irradiance in the third wavelength band that is less than a predetermined threshold into the maintenance work environment.

[0093] In this way, the tampering detection system 100 can disable the detection of tampering during maintenance work by using a pre-specified light source unit 2. Furthermore, since the light source unit 2 can be a white light source such as an LED light, work efficiency can be improved. On the other hand, even if a third party knows that a white light source is being used in the maintenance work environment, they cannot know the emission wavelength characteristics of the light source unit 2. In that case, if a third party opens the housing 11 thinking that tampering will not be detected with a white light source, and a white light source with different emission wavelength characteristics than the light source unit 2 is used, the tampering detection device 3 can correctly detect that it has been tampered with.

[0094] (10) According to the tenth embodiment, the method for detecting unauthorized opening includes the steps of: a first light detection unit 31 provided inside a light-blocking housing 11 detecting light in a predetermined wavelength band; and detecting that the housing 11 has been opened unauthorizedly based on the detection result of the first light detection unit 31, wherein in the step of the first light detection unit 31 detecting light, it detects light in a second wavelength band different from the light in a first wavelength band emitted by the light source unit 2 of the maintenance work environment, and in the step of detecting that the housing 11 has been opened unauthorizedly, it detects that the housing 11 has been opened unauthorizedly when light in the second wavelength band is detected.

[0095] In this way, unlike conventional methods using magnets, the first optical detection unit, whose installation location is difficult to identify from outside the housing 11, makes it difficult for a third party to bypass the detection of unauthorized opening by avoiding the installation location of the first optical detection unit 31 when opening the package. Furthermore, while the detection of unauthorized opening can be disabled in a maintenance work environment, it becomes difficult for a third party who is unaware of the conditions of the maintenance work environment to bypass the detection of unauthorized opening.

[0096] (11) According to the eleventh embodiment, the method for detecting unauthorized opening includes the steps of: a first light detection unit 31 provided inside a light-blocking housing 11 detecting light in a predetermined wavelength band; and detecting that the housing 11 has been opened unauthorizedly based on the detection result of the first light detection unit 31, wherein in the step of the first light detection unit 31 detecting light, it detects light in a third wavelength band whose irradiance is less than a predetermined threshold among the wavelength bands included in the light emitted from the light source unit 2 of the maintenance work environment, and in the step of detecting that the housing 11 has been opened unauthorizedly, it detects that the housing 11 has been opened unauthorizedly when light in the third wavelength band is detected.

[0097] In this way, the detection of unauthorized access can be disabled in the maintenance work environment, while at the same time making it difficult for a third party who is unaware of the conditions of the maintenance work environment to disable the detection of unauthorized access.

[0098] According to the above embodiment, it is possible to make it difficult for a third party to disable the detection of unauthorized opening of the enclosure.

[0099] 100 Tampering Detection System 1 Device 11 Housing 12 Cover 2 Light Source Unit 21 Light Source 22 Filter 3 Tampering Detection Device 31 First Light Sensor (First Light Detection Unit) 311 Photodiode 312 Conversion Circuit 313 Comparator 314 Filter 315 A / D Converter 32 Detection Unit 321 Logic Circuit (AND Gate) 322 Amplification Circuit 323 Comparator 324 Logic Circuit (AND Gate) 325 Logic Circuit (XOR Gate) 33 Second Light Sensor (Second Light Detection Unit) 331 Photodiode 332 Conversion Circuit 333 Comparator 334 Filter

Claims

1. A device for detecting unauthorized opening, comprising: a first light detection unit provided inside a light-blocking enclosure for detecting light in a predetermined wavelength band; and a detection unit for detecting that the enclosure has been opened illegally based on the detection result of the first light detection unit, wherein the first light detection unit detects light in a second wavelength band different from light in a first wavelength band emitted by a light source in the maintenance work environment; and the detection unit detects that the enclosure has been opened illegally when light in the second wavelength band is detected.

2. The tampering detection device according to claim 1, wherein the first light detection unit has a photodiode that is sensitive to the second wavelength band, or a photodiode covered with a filter that blocks light in the first wavelength band.

3. A device for detecting unauthorized opening, comprising: a first light detection unit provided inside a light-blocking enclosure for detecting light in a predetermined wavelength band from the light; and a detection unit for detecting that the enclosure has been opened illegally based on the detection result of the first light detection unit, wherein the first light detection unit detects light in a third wavelength band whose irradiance is less than a predetermined threshold from the wavelength band included in the light emitted from a light source in the maintenance work environment; and the detection unit detects that the enclosure has been opened illegally when light in the third wavelength band is detected.

4. The tampering detection device according to claim 3, wherein the first light detection unit has a photodiode that is sensitive to the third wavelength band, or a photodiode covered with a filter that transmits only light in the third wavelength band.

5. The tampering detection device according to claim 3, further comprising a second light detection unit provided inside the housing, which detects light in a fourth wavelength band having the greatest irradiance among the wavelength bands included in the light emitted from the light source of the maintenance work environment, wherein the detection unit detects that the housing has been illegally opened when light in the third wavelength band is detected and light in the fourth wavelength band is not detected.

6. The unauthorized opening detection device according to claim 5, wherein the detection unit detects that the housing has been opened illegally when light from both the third wavelength band and the fourth wavelength band is detected, and the value obtained by multiplying the detected light intensity of the third wavelength band by a predetermined factor is greater than the detected light intensity of the fourth wavelength band.

7. The tamper-evident device according to claim 5, wherein the second light detection unit has a photodiode sensitive to the fourth wavelength band, or a photodiode covered with a filter that transmits only light in the fourth wavelength band.

8. A tampering detection system comprising: a tampering detection device according to claim 1 or 2; and a light source unit that emits light in the first wavelength band into the maintenance work environment.

9. A tampering detection system comprising: a tampering detection device according to any one of claims 3 to 7; and a light source unit that emits light with an irradiance in the third wavelength band that is less than a predetermined threshold into a maintenance work environment.

10. A method for detecting unauthorized opening of a housing, comprising the steps of: a first light detection unit provided inside a light-blocking housing detects light in a predetermined wavelength band from the light; and a step of detecting that the housing has been opened illegally based on the detection result of the first light detection unit, wherein in the step of detecting light, the first light detection unit detects light in a second wavelength band different from light in a first wavelength band emitted by a light source in the maintenance work environment; and in the step of detecting that the housing has been opened illegally, if light in the second wavelength band is detected, the housing has been opened illegally.

11. A method for detecting unauthorized opening of a housing, comprising the steps of: a first light detection unit provided inside a light-blocking housing detects light in a predetermined wavelength band from the light; and a step of detecting that the housing has been opened illegally based on the detection result of the first light detection unit, wherein in the step of detecting light, the first light detection unit detects light in a third wavelength band whose irradiance is less than a predetermined threshold from the wavelength band included in the light emitted from a light source of the maintenance work environment; and in the step of detecting that the housing has been opened illegally, if light in the third wavelength band is detected, the housing has been opened illegally.

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