Detection Equipment

Abstract

To provide a device for detecting a person and an object approaching at a speed higher than a body motion of a user even when they are hidden within shadows.SOLUTION: A detection device (1) includes: a main body case (2) to be mounted on a body of a user; a detection section (20) constituted by a micro-wave Doppler sensor housed inside the main body case; a differentiation section (42) for generating a differential signal which indicates a time change of an output signal from the detection section; a determination section (44) for defining a code of the output signal when an object is approaching the detection section as a positive code and defining the code of the output signal when the object is leaving from the detection section as a negative code, and then determining that an approaching person approaching the user exists when magnitude of amplitude of the differential signal exceeds a threshold corresponding to a body motion of the user and also the code of the differential signal becomes negative from positive; and a notification section (3b) for notifying the user of a determination result of the determination section.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a detection device. [Background technology]

[0002] Patent Document 1 describes a danger warning system including a warning unit and an accessory for mounting the warning unit on the body, the warning unit including a measuring unit for determining the distance from the surface of the body to an object in the normal direction, a physical stimulation unit for providing stimulation to the body, and a processing unit for processing the determined distance and controlling the physical stimulation unit. Patent Document 2 describes a rear monitoring device mounted on the human body or a portable object nearby, which emits monitoring electromagnetic waves to a rear monitoring area of ​​the human body, detects a monitored object present in the rear monitoring area based on the monitoring electromagnetic waves, outputs an alarm signal, and issues a danger notification to the human body based on the alarm signal. Patent Document 3 describes an accessory for the hearing impaired that includes a Doppler sensor for detecting the approach of a moving object and notifies the user when the approach of the moving object is detected. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-5820 A [Patent Document 2] JP 2011-8746 A [Patent Document 3] JP 2010-66276 A Summary of the Invention [Problem to be solved by the invention]

[0004] Humans have a very weak sense of attention when it comes to blind spots behind them. For example, there has been an increase in incidents of random street thugs and, more recently, incidents of police officers being attacked by suspicious people and having their guns stolen. This has created a demand for devices that can detect and warn of people approaching from behind in blind spots so that the first attack from a suspicious person can be avoided. Technology has been proposed for detecting people approaching from behind using ultrasound, but because ultrasound reflects off of a rigid object, it may not be possible to detect people approaching from behind objects such as walls. In addition, for example, when a person wearing a detection device is walking, they are also moving, making it difficult to distinguish between the movement of an approaching person and their own movement.

[0005] An object of the present invention is to provide a device that detects a person or object approaching at a speed faster than the body movement of the user, even if the person or object is hidden behind an object. [Means for solving the problem]

[0006] There is provided a detection device comprising: a main body case attached to a user's body; a detection unit consisting of a microwave Doppler sensor housed in the main body case; a differentiation unit that generates a differential signal indicating a time change in an output signal from the detection unit; a determination unit that determines that there is an individual approaching the user when the amplitude of the differential signal exceeds a threshold value corresponding to the user's body movement and the sign of the differential signal changes from positive to negative, defining the sign of the output signal as positive when an object is approaching the detection unit and the sign of the output signal as negative when an object is moving away from the detection unit; and a notification unit that notifies the user of the determination result of the determination unit.

[0007] The detection device preferably further includes a setting unit that sets a threshold value for each user based on the amplitude of the differential signal corresponding to the body movement of the user. The detection device preferably further includes an elastic band for fixing the main case to the body of the user.

[0008] The detection device further has a flat battery and a shielding plate that prevents microwaves from the detection unit from being reflected by the user's body and entering the detection unit, the detection unit having a sensor board on which an antenna pattern of a microwave Doppler sensor is formed, and it is preferable that the battery and shielding plate are arranged within the main body case on a side closer to the surface of the main body case that is attached to the user than the sensor board, and the surface of the sensor board closer to the attachment surface is covered by the battery and shielding plate.

[0009] It is preferable that the detection device further has a control board on which a control circuit constituting a differentiation unit and a judgment unit is mounted, and that the sensor board is raised higher than the control board relative to the mounting surface within the main body case and positioned in a position that does not overlap with the control board when viewed from above the mounting surface.

[0010] It is preferable that the notification unit is composed of a vibration motor and notifies the determination result of the determination unit by vibration, the antenna pattern is formed on one end side of the sensor substrate, and the vibration motor is arranged on the side of the end opposite to the one end of the sensor substrate.

[0011] It is preferable that the notification unit is composed of a vibration motor and notifies the determination result of the determination unit by vibration, and that the determination unit does not determine the presence or absence of an approaching person while the vibration motor is vibrating. It is preferable that the detection device further has a motor case that houses the vibration motor, and that the motor case is separate from the main body case. It is preferable that the detection device further has a cushioning material arranged between the main body case and the motor case. Effect of the Invention

[0012] According to the above-mentioned detection device, it is possible to detect a person or object approaching at a speed faster than the body movement of the user, even if the person or object is hidden behind an object. [Brief description of the drawings]

[0013] [Figure 1] 1A and 1B are schematic plan and cross-sectional views of a detection device 1. [Diagram 2] FIG. 2 is a functional block diagram of the detection device 1. [Diagram 3] 2A and 2B are diagrams showing a wearing cover 5 and a wearing state thereof. [Figure 4] 4 is a waveform diagram for explaining the function of the control unit 40. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The detection device will now be described with reference to the drawings, although it should be understood that the invention is not limited to the drawings or to the embodiments described below.

[0015] 1(A) and 1(B) are schematic plan and cross-sectional views of the detection device 1. FIG. 1(B) shows a cut surface of the detection device 1 taken along line IB-IB in FIG. 1(A). FIG. 2 is a functional block diagram of the detection device 1. The detection device 1 is a wearable device that uses a built-in microwave Doppler sensor to detect an individual approaching from behind, which is the blind spot of the user, and is intended for use by police officers or security guards for security purposes, or by ordinary people for crime prevention. The detection device 1 is worn on the back of the user's body (for example, the waist or back), learns the user's walking and body movements, detects an individual approaching from behind the user at a speed faster than the detected speed, and alerts the user by vibration.

[0016] The detection device 1 has a main body case 2, a motor case 3, and a cushioning material 4. The main body case 2 has, for example, a box-like shape, and houses a battery 2a, a shielding plate 2b, a control board 2c, and a sensor board 2d, as shown in Fig. 1(A) and Fig. 1(B). Reference numeral 90 denotes the user's body, and the bottom surface of the main body case 2 is the surface that is attached to the user. In Fig. 1(A), the main body case 2 and the motor case 3 are illustrated as transparent so that the internal structure can be seen. As shown in Fig. 2, the detection device 1 has, as functional blocks, an operation unit 10, a detection unit 20, a storage unit 30, and a control unit 40 within the main body case 2.

[0017] The battery 2a is a power source for the detection device 1, and is, for example, flat (rectangular), has approximately the same size as the bottom surface of the main case 2, and is disposed at the bottom inside the main case 2. The shielding plate 2b is a conductive plate for shielding radio waves from the detection unit 20, and has, for example, approximately the same size as the bottom surface of the main case 2, and is disposed above the battery 2a inside the main case 2 so as to cover and conceal the battery 2a. The control board 2c is a board on which a control circuit C such as a microcomputer constituting the memory unit 30 and the control unit 40 is formed, and in the illustrated example, has a size less than half that of the shielding plate 2b, and is disposed above the shielding plate 2b. A button-shaped operation unit 10 is also mounted on the control board 2c.

[0018] The sensor board 2d is a board on which an antenna pattern P of a microwave Doppler sensor is formed on the upper surface, and in the illustrated example, is less than half the size of the shielding plate 2b, and is supported by a support column 2e standing on the shielding plate 2b and disposed above the shielding plate 2b. Reference numeral 2f denotes wiring that electrically connects the control board 2c and the sensor board 2d. The detection unit 20 is a microwave Doppler sensor, and is composed of the sensor board 2d and the antenna pattern P housed in the main body case 2.

[0019] The microwave Doppler sensor is a radio wave sensor, and when the main body case 2 is attached to the back of the user, the skin on the back very close to the sensor moves slightly relative to the user's skeleton, so that the sensor reacts to the user's own movement and changes the output signal even if no one is approaching. Therefore, in the detection device 1, in order to prevent the microwaves from the detection unit 20 from being reflected by the user's body and entering the detection unit 20, the entire bottom surface of the sensor board 2d, which is the surface facing the user, is covered with a shielding plate 2b, and a rectangular battery 2a is further placed on the lower side. That is, the battery 2a, the shielding plate 2b, and the sensor board 2d are placed so that they are layered in this order from the side closest to the user when the main body case 2 is attached to the user's body, and the surface of the sensor board 2d close to the attachment surface is covered with the battery 2a and the shielding plate 2b.

[0020] This arrangement blocks the back sensitivity of the detection unit 20, i.e., the microwaves that go to the user side (the back side of the detection device 1) and return, suppressing noise in the output signal of the detection unit 20 caused by the movement of the user's skin. Microwaves are also reflected by the battery 2a, shielding plate 2b, and control board 2c, but since these are always at a constant distance from the microwave Doppler sensor, they do not affect the output signal. Furthermore, the battery 2a is the heaviest of the battery 2a, shielding plate 2b, control board 2c, and sensor board 2d, and since this heavy component is arranged on the wearing surface side, there is also the advantage that the detection device 1 sits comfortably when worn.

[0021] The order of the shielding plate 2b and the battery 2a may be reversed, as long as the sensor board 2d is disposed above the battery 2a and the shielding plate 2b, i.e., on the side farther from the mounting surface of the main body case 2. The shielding plate 2b needs to cover, at the very least, the entire bottom surface of the sensor board 2d, and if the battery 2a can sufficiently block the back sensitivity of the detection unit 20, the shielding plate 2b may be omitted.

[0022] 1(A) and 1(B), the sensor board 2d is raised higher than the control board 2c relative to the mounting surface of the main body case 2 by support columns 2e, and is disposed at a position where it does not overlap with the control board 2c when viewed from above the mounting surface. That is, the sensor board 2d and the control board 2c are disposed offset from each other in the thickness direction and in a plane perpendicular to the thickness direction within the main body case 2. Although the frequency of microwaves is about several GHz, harmonics of the clock of the microcomputer included in the control circuit C may affect the output signal of the microwave Doppler sensor and become a noise source, so the sensor board 2d and the control board 2c are disposed as far apart as possible.

[0023] The motor case 3 has a box-like shape smaller than the main body case 2, and houses the motor board 3a and the vibration motor 3b. The motor board 3a is a board for the vibration motor 3b, and the vibration motor 3b is mounted on the motor board 3a. The vibration motor 3b is an example of an alarm unit, and alarms the user of the detection result of the detection device 1 by vibrating under the control of the control unit 40. Reference numeral 3c denotes a wire that electrically connects the control board 2c and the motor board 3a.

[0024] The cushioning material 4 is a member for preventing the vibration of the vibration motor 3b from being transmitted to the main body case 2, and is arranged to encase the motor case 3. The cushioning material 4 may be any material capable of absorbing shock, such as rubber. In the illustrated example, the main body case 2 and the motor case 3 are integrated via the cushioning material 4, but the cushioning material 4 may be omitted if the space between the main body case 2 and the motor case 3 is large enough that the vibration of the vibration motor 3b is not transmitted to the main body case 2. The motor board 3a and the vibration motor 3b may be wrapped in the cushioning material 4 and arranged inside the main body case 2, but in order to prevent the vibration from being transmitted to the sensor board 2d, it is preferable to separate the motor case 3 from the main body case 2 and further sandwich the cushioning material 4 between them.

[0025] 1(A), the antenna pattern P is formed on one end E1 side of the sensor substrate 2d, and the vibration motor 3b is disposed on the side of the end E2 opposite to the one end E1 of the sensor substrate 2d. In order to prevent the vibration motor 3b from becoming a noise source for the detection unit 20, it is preferable to dispose the antenna pattern P on the sensor substrate 2d at a position as far away as possible from the vibration motor 3b in this manner.

[0026] 3(A) and 3(B) are diagrams showing the wearing cover 5 and a state in which the cover is worn. When using the detection device 1, the detection device 1 may be stored in the wearing cover 5 with a band 5b, and the wearing cover 5 may be attached to the back or waist of the user with the band 5b, so that the distance and positional relationship between the detection device 1 and the user's body does not change. FIG. 3(A) shows a state in which the wearing cover 5 is fixed to the waist of the user 90. In the illustrated example, the wearing cover 5 is a waist pouch that can be worn on the waist, and the detection device 1 can be stored inside by opening and closing the fastener 5a. The band 5b is for fixing the main case 2 to the user's body, and is preferably stretchable.

[0027] 2 is a volatile or non-volatile memory device, and stores information necessary for the operation of the detection device 1. The control unit 40 has a timer unit 41, a differentiation unit 42, a setting unit 43, and a determination unit 44 as functional blocks realized by a microcomputer included in the control circuit C.

[0028] FIG. 4 is a waveform diagram for explaining the function of the control unit 40. FIG. 4 shows the waveforms of the output signal c1 of the microwave Doppler sensor and the differential signal c2 showing its time change. The horizontal axis t is time, and the vertical axis is amplitude, with the upper side of the t axis being positive and the lower side being negative. For the vertical axis, the sign of the output signal c1 when there is an object approaching the detection unit 20 is defined as positive, and the sign of the output signal c1 when there is an object moving away from the detection unit 20 is defined as negative. The illustrated waveforms are for a case in which the wearer (user) of the detection device 1 is stationary in period T0, walking in period T1, someone approaches the wearer at the time of arrows a1 to a3 in period T1, and someone moves away from the wearer at the time of symbol b1.

[0029] Since the microwave Doppler sensor outputs a voltage signal whose magnitude corresponds to the speed, the amplitude of the output signal c1 is small during the period T0 when there is no movement, and becomes larger during the period T1 than during the period T0 according to the speed of the wearer's body movement, and becomes particularly large at the time points indicated by the arrows a1 to a3 and b1 where someone is approaching or moving away from the wearer. The waveform of the differential signal c2 represents the time change of the signal according to the speed, and therefore represents the acceleration of an object moving relative to the detection unit 20. +M and -M in the figure correspond to the upper and lower limit values ​​of the amplitude of the differential signal c2, which indicates the wearer's body movement. From the waveform of the differential signal c2, it can be seen that when the amplitude of the differential signal c2 exceeds +M at the time points indicated by the arrows a1 to a3, someone starts to move toward the wearer at a speed faster than the wearer's movement, and then when it falls below -M, the person's speed decreases and stops moving temporarily.

[0030] At the time of arrow b1, when the amplitude of the differential signal c2 falls below -M, someone starts moving away from the wearer at a speed faster than the wearer's movement, and then when it exceeds +M, it can be seen that the person's speed decreases and stops. In this way, if a person moving toward or away from the wearer moves and stops, acceleration increases and decreases, so it can be determined from the peak in the waveform of the differential signal c2 that there is someone approaching or leaving, and it can be distinguished from the sign of the peak whether it is approaching or leaving. In particular, a person approaching the wearer stops temporarily when approaching the wearer, accelerating in the approaching direction and then decelerating, so if there is an approaching person, a peak on the + side followed by a peak on the - side appears in the waveform of the differential signal c2.

[0031] The timer unit 41 is composed of a known clock circuit, and measures the elapsed time during processing by the setting unit 43 and the determination unit 44. The differentiator 42 differentiates the output signal c1 of the microwave Doppler sensor with respect to time, and generates a differential signal c2 that indicates the change over time of the output signal c1.

[0032] When the user presses a button on the operation unit 10, the setting unit 43 learns the body movement of the user (wearer) for a certain period of time, such as 10 seconds, and determines the upper limit value (M in FIG. 4) of the amplitude of the differential signal c2 corresponding to the body movement of the user. This value becomes a threshold value for determining that there is someone moving at a faster speed than the user. Since the magnitude of the body movement differs from person to person, the setting unit 43 obtains the maximum and minimum values ​​of the amplitude of the differential signal c2 corresponding to the body movement of the user for each user within a certain period of time, sets the larger of the absolute values ​​of the two as the threshold value M, and stores it in the storage unit 30. Alternatively, the setting unit 43 may set the obtained maximum and minimum values ​​as the threshold values ​​on the positive and negative sides of the amplitude of the differential signal c2, respectively.

[0033] Alternatively, instead of a button operated by the user, the operation unit 10 may be a switch mechanism on the bottom surface of the main body case 2 that is turned on when the user fastens the wearing cover 5 to the body. In this case, the setting unit 43 automatically sets the threshold value M for the user when the detection device 1 is worn, regardless of the user's operation.

[0034] The determination unit 44 determines that there is a person approaching the user when the amplitude of the differential signal c2 exceeds a threshold M according to the user's body movement and the sign of the differential signal c2 changes from positive to negative. That is, the determination unit 44 determines that there is an approaching person when the amplitude of the differential signal c2 exceeds +M and then falls below -M, as shown by arrows a1 to a3 in the example of FIG. 4. Conversely, while the amplitude of the differential signal c2 is equal to or less than the threshold M, or when the sign of the differential signal c2 changes from negative to positive even if the amplitude exceeds the threshold M, the determination unit 44 determines that there is no approaching person. Then, only when it is determined that there is an approaching person, the determination unit 44 vibrates the vibration motor 3b for a certain period of time, such as three seconds, to notify the user of the determination result.

[0035] It is preferable that the determination unit 44 does not determine the presence or absence of an approaching individual while the vibration motor 3b is vibrating (masks the determination) so as not to erroneously determine that the fluctuation of the output signal c1 caused by the vibration of the vibration motor 3b is due to an approaching individual (i.e., to prevent multiple detections and noise). The determination result may be notified to the user by a sound such as a buzzer, but since the detection device 1 is intended to avoid danger from suspicious individuals, it is preferable to use vibration that can notify the user silently. Alternatively, the detection device 1 may be combined with an earphone, and the earphone may generate a sound via wireless communication from the control unit 40 to notify the user of the determination result of an approaching individual silently.

[0036] The detection device 1 can suppress noise caused by the movement of the user's skin and distinguish between the user's own body movement and the movement of an approaching person, so it can detect people or objects approaching the user with high accuracy. Because microwaves have higher penetrating properties than ultrasound, a microwave Doppler sensor can be used to detect people hiding behind objects such as walls. [Explanation of symbols]

[0037] 1. Detection device 2 Main unit case 3 Motor case 4 Cushioning material 5 Installation cover 10 Control section 20 Detection unit (microwave Doppler sensor) 30 Storage section 40 Control section

Claims

1. A main body case that is attached to the user's body; a detection unit that is housed in the main body case and outputs an output signal that indicates approach and departure of an object; a determination unit that determines that an object is approaching the user based on the output signal, A setting unit that determines a threshold value based on a change in response to a body movement of the user, The determination unit detects an object approaching the user based on a value determined in response to the output signal exceeding the threshold value. A detection device comprising:

2. The detection device according to claim 1 , wherein the setting unit learns a body movement of the user over a certain period of time and determines the threshold value in accordance with the learned body movement.

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