JP5106925B2 - Human body detection apparatus and human body detection method - Google Patents

Description

  The present invention relates to a human body detection device and a human body detection method.

  2. Description of the Related Art Conventionally, there is a human body detection device that utilizes the fact that the capacitance of an antenna circuit changes as a human body approaches an antenna electrode. In this human body detection device, a change in the circuit current based on a change in the capacitance of the antenna circuit is detected as a voltage value, and it is determined whether or not the human body has approached by comparing this voltage value with a preset reference voltage. Like to do.

  However, in the human body detection device, the capacitance of the antenna circuit changes due to changes in the surrounding environment (temperature, rain, etc.), so that the detection accuracy is not stable and there is a risk of malfunction.

  For this reason, there is a known one in which the detection accuracy is improved by changing the reference voltage in accordance with the change in the outside air temperature (for example, see Patent Document 1).

JP-A-7-189538

  However, even the conventional human body detection device cannot cope with changes in environmental conditions other than the outside air temperature, and the problem that the detection accuracy is still unstable cannot be solved.

  Accordingly, an object of the present invention is to provide a human body detection device and a human body detection method capable of obtaining desired detection accuracy sufficiently corresponding to changes in various environmental conditions.

As a means for solving the above problems, the present invention provides:
The human body detection device
Antenna means that is electrically connected to the antenna electrode, converts the capacitance of the antenna electrode into a voltage and outputs it as a measurement voltage;
Measurement voltage storage means for storing a measurement voltage output from the antenna means;
Wherein among the measured voltage past measurement voltage stored in the storage means, a sensing voltage which is a first mean value of the set number of times from the latest one, the first setting number of times from the latest one used during the sensing voltage calculation The human body approach determines whether or not the human body has approached the antenna electrode by comparing the reference voltage, which is the average value for the second set number of times, from the past measured voltage further than the oldest measured voltage of the measured value A determination means;
With
The first set number is less than the second set number.

  With this configuration, it can be determined that the human body has approached only by temporarily changing the measurement voltage, and the detection accuracy can be improved.

  It is preferable to further include an extraction time adjusting means for adjusting a cycle for extracting the measurement voltage.

  With this configuration, it is possible to adjust the sensitivity when determining whether or not a human body has approached. If the extraction cycle of the measurement voltage is shortened, the sensitivity becomes higher, and conversely, if it is made longer, it can be prevented that the sensitivity becomes too high.

  The human body approach determining means determines whether or not the human body has approached the antenna electrode at a constant time period, and otherwise, the sleep mode is preferable in that power consumption can be reduced.

Timer means for measuring the elapsed time since the determination by the human body approach determination means is performed;
A determination result storage means for storing a determination result in the human body approach determination means until an elapsed time measured by the timer means passes a set time;
Is preferably further provided.

  With this configuration, the determination result can be held until the set time elapses, and the determination result can be prevented from being instantaneously switched (chattering), and a stable determination result can be obtained.

Further, the present invention provides a means for solving the above-described problems,
A voltage output step for outputting a measurement voltage based on the capacitance of the antenna electrode that changes due to the approach of the human body;
Comparing the measured voltage output in the voltage output step with a reference voltage for determining the approach of the human body, and satisfying the setting condition, thereby determining that the human body has approached the antenna electrode; and ,
A human body detection method including:
A measurement voltage storage step of storing the measurement voltage output in the voltage output step;
The human body approach determination step includes the latest measurement voltage stored in the measurement voltage storage step and the latest voltage used when calculating the detection voltage, which is an average value for the first set number of times from the latest one. Whether the human body has approached the antenna electrode by comparing the reference voltage, which is the average value of the second set number of times from the past measured voltage, than the oldest measured voltage of the measured value for the first set number of times It is to determine whether or not.

  According to the present invention, since the reference voltage is an average value for the set number of past measurement voltages, it is automatically set to an appropriate value according to environmental changes while eliminating the influence of superimposed noise. Can be changed. Therefore, it is possible to accurately detect the human body.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings.

  FIGS. 1A and 1B show an example in which the human body detection device 2 according to the present embodiment is adopted for a door knob 1 of a vehicle. As shown in FIG. 2, the human body detection device 2 includes a ferrite antenna 5 and an antenna electrode 6 accommodated in a first accommodating recess 4 of a casing 3, and a printed circuit board 8 accommodated in a second accommodating recess 7. is there.

  The ferrite antenna 5 is obtained by winding a wire 10 around the center of a rectangular plate-shaped ferrite core 9 and outputs a signal when an electronic key (not shown) approaches.

  The antenna electrode 6 is formed of a conductive plate-like body (1 cm × 4 cm). For example, the capacitance increases when a human body (here, a hand) approaches (holds the door knob 1). If the capacitance changes at the antenna electrode 6, it is converted into a voltage value and input to one input terminal of the EXOR circuit 11 constituted by electronic components mounted on the printed circuit board 8.

  Various electronic components are mounted on the printed circuit board 8, and an EXOR circuit 11 (exclusive-OR circuit) to which an output signal from the antenna electrode 6 is input and an output terminal of the EXOR circuit 11 are connected as shown in FIG. Integrated circuit 12, a microcomputer 13 to which an output signal from the integrating circuit 12 is input (microcomputer; here, an IC (Integrated Circuit) is used), and a power supply circuit 14 for supplying power to the microcomputer 13. Etc. Here, the EXOR circuit 11 and the integrating circuit 12 constitute the antenna means according to the present invention.

  The voltage output from the waveform generator 15 of the microcomputer 13 is input to the first input terminal 11a and the second input terminal 11b of the EXOR circuit 11, respectively. The first input terminal 11a receives an output signal from the antenna electrode 6, that is, a signal waveform affected by a change in capacitance. A reference signal (square wave) is input to the second input terminal 11b via the capacitor C6 for waveform adjustment. Based on these signals, a predetermined signal is output from the output terminal as will be described later.

  FIG. 6 shows an example of a signal (voltage) waveform input to each of the input terminals 11a and 11b, and an example of an output waveform from the output terminal when these signals are input. In a state where no human body or the like is detected by the antenna electrode 6, the same square wave is input to any input terminal. Therefore, the inputs at both input terminals 11a and 11b match (on / on or off / off), and the output is an off signal (0 V). However, if the input voltages to both input terminals do not match, a waveform adjusting capacitor may be connected to the input line to the first input terminal 11a. On the other hand, when a human body or the like is detected by the antenna electrode 6, the capacitance is increased, and the input waveform to the first input terminal 11a becomes a mountain shape. As a result, the output waveform is a square wave having a shorter cycle than that of the second input terminal 11b.

  The integrating circuit 12 includes a diode D2 and two capacitors C8 and C9. The integrating circuit 12 integrates a square wave output from the EXOR circuit 11 and converts it into an analog voltage (constant voltage). When the human body is not detected by the antenna electrode 6, the output here is naturally 0V.

  The microcomputer 13 includes a waveform generation unit 15, an oscillation unit 16, a reset unit 17, a storage unit 18, a control unit 19, and the like. The input port AN0 (A / D (Analog / Digital) input) is connected to the antenna electrode 6. Are output from the EXOR circuit 11 via the integration circuit 12. The microcomputer 13 determines whether or not the door knob 1 is caught by a human hand based on a signal input to the input port AN0. As will be described in detail later, an input measurement voltage is compared with a reference voltage, and if the difference exceeds a set value, an ON signal is output from the output terminal GP2 (output unit), otherwise an OFF signal is output. Is output. The output of the output terminal GP2 is input to the base of the transistor T1. The transistor T1 is turned on when the on signal is input to the base and is grounded, the output state at the output terminal 2 is turned off, and conversely, the transistor T1 is turned off when the off signal is input to the base. The output state at the output terminal 2 is turned on. The output terminal 2 is connected to a predetermined input port of an ECU (Electronic Control Unit) (not shown). The ECU detects that a human body has approached the doorknob 1 when the transistor T1 is turned on, and outputs an LF (Low Frequency) oscillation wave that activates the electronic key from the ferrite antenna 5 toward the electronic key (not shown). To do.

  The power supply circuit 14 includes a power supply IC 21, capacitors C1, C2, and the like, and outputs a predetermined voltage (3V in this case) suitable for use in the microcomputer 13 to the reset unit 17MCLR.

  Next, the operation of the human body detection device 2 having the above-described configuration, that is, the determination process (human body approach determination process) for determining whether or not the door knob 1 has been captured by the human hand with the microcomputer 13 will be described with reference to the flowcharts of FIGS. .

  First, each data stored in the storage unit 18 is initialized. Here, the 40-second timer, the 0.6-second timer, the number of times, the reference voltage, the sense voltage, the measured voltage, and the determination output are all reset to 0 (step S1). As will be described in detail later, the 40-second timer is a timer for setting the ON output output from the output terminal GP2 of the microcomputer 13 to a maximum of 40 seconds, and the 0.6-second timer is output from the output terminal GP2 of the microcomputer 13. This is a timer for maintaining the ON output to be performed for at least 0.6 seconds.

  Then, it is determined whether or not the determination output is on (= 1) (step S2). Since the determination output is off (= 0) in the initialized state (step S2: NO), the microcomputer 13 is in the sleep mode (= low power consumption mode: a state where only a part of the microcomputer 13 is activated. Then, the minimum necessary voltage is input from the power supply circuit 14 and the determination output from the antenna electrode 6 can be received.) (Step S3), and the system waits until a predetermined time (for example, 10 msec) elapses (step S3). Step S4). On the other hand, if the determination output is on (= 1) as described later (step S2: YES), the process waits until a predetermined time (for example, 10 msec) elapses (step S5). As described above, the steps S4 and S5, which are extraction timing adjustment means, can operate the microcomputer 13 intermittently at predetermined time units to suppress unnecessary power consumption and adjust the cycle for extracting the measurement voltage Vn. Is possible.

  When waiting for a predetermined time, the number of times of measurement n is counted (step S6). Based on the input signal from the antenna electrode 6, the determination signal is output from the EXOR circuit 11, and the analog signal (voltage) converted from the digital signal by the integrating circuit 12 is obtained. ) As a measured voltage Vn and stored in the storage unit 18 as a measured voltage storage means (step S7).

  Subsequently, it is determined whether or not the number of measurements n of the measurement voltage Vn read in the past is 4 or less (step S8). That is, when the number of measurement voltages Vn stored in the storage unit 18 is 4 or less (step S8: YES), the average value of the stored measurement voltages Vn is set as the sense voltage Vk (step S9). If the number of measurements is from the initial state to the fourth, this process is performed. If the number of measurement voltages Vn stored in the storage unit 18 exceeds 4 (step S8: NO), the average value of only four of the stored measurement voltages Vn from the latest is used as the sense voltage Vk. (Step S10). In this way, by using the average value of the measurement voltage Vn as the sense voltage, it is possible to prevent the influence of noise such as a surge voltage. Note that when the number of measurements n exceeds 4, only the latest four measurement results are used in consideration of the balance between prevention of misjudgment due to noise and responsiveness when the input changes. Is.

  Next, it is determined whether or not the determination output is off (= 0) (step S11). In the initial state, the determination output is 0 because it is reset in step S1. As will be described later, the determination output is maintained at 0 unless the difference between the measurement voltage Vn and the reference voltage Vt exceeds the set value in step S17. If the determination output is 0 (step S11: YES), it is determined whether the number of measurements is 20 or more (step S12). If the number of times of measurement is 20 times or more (step S12: YES), an average value of 20 times is calculated from the latest measured voltage Vn stored as the reference voltage Vt (step S13). If the number of measurements is less than 20 (step S12: NO), the sense voltage Vt is obtained by dividing the total value of the measurement voltages Vn by the value obtained by adding 1 to the number of measurements (step S14). In this case, the reference voltage Vt is always smaller than the sense voltage Vk.

  As described above, the average value of the latest 20 measured voltages among the past measured voltages Vn (the value obtained by dividing the total value of the measured voltages Vn up to 20 times by n + 1) is used as the reference voltage Vt. Therefore, if the measurement voltage Vn changes, the reference voltage Vt changes with a delay compared to the measurement voltage Vn or the sense voltage Vk that is the average value of the latest four times (until it exceeds four). For example, as shown in the graph of FIG. 7, when the sensing voltage Vk changes, the reference voltage Vt changes after the change. Thereby, even if the sensing voltage Vk changes suddenly, the reference voltage Vt does not follow and a stable detection state can be obtained. If the sense voltage Vk changes abruptly, the voltage difference from the reference voltage Vt increases. On the other hand, if the sensing voltage Vk changes slowly, the voltage difference from the reference voltage Vt does not become so large and remains within a certain range. Further, if the measurement voltage Vn is changed and a voltage difference from the reference voltage Vt is generated, if the same state is maintained thereafter (for example, about 200 msec or more), both voltage values become substantially the same value.

  Therefore, it is determined whether or not 0.6 seconds have been counted by the 0.6 second timer (step S15). If the 0.6 second timer is not activated (0.6T = 0, that is, judgment output = 0), or if 0.6 second is counted (step S15: NO), the sense voltage Vk and the reference voltage Vt It is determined whether or not the difference is equal to or greater than a set value (0.09V = 90 mV) (step S17). If the voltage difference is less than or equal to the set value (step S17: NO), the determination output is maintained off (= 0), and the process returns to step S2 to maintain the sleep mode. Therefore, as long as the determination output is not turned on (= 1), the sleep mode can be maintained and power consumption can be suppressed. On the other hand, if the voltage difference is equal to or larger than the set value (step S17: YES), it is determined that the door knob 1 is grasped, the output signal is turned on (= 1), and the 0.6 second timer and the 40 second timer are incremented. (Addition and counting) are performed (step S18). Since the count cycle (operation cycle by steps S4 and S5) is 10 msec, with the 0.6 second timer, the count number becomes 0.6 seconds when it reaches 60 times, and with the 40 second timer it becomes 40 seconds when it reaches 4000 times. It becomes.

  If 0.6 seconds have not elapsed (step S15: YES), the time is incremented by a predetermined time (10 msec) (step S16), and the process returns to step S2 to continue the process. That is, when the 0.6 second timer is in operation, the determination output is turned on because the process returns to step S2 without performing the comparison determination (step S17) between the sense voltage Vk and the reference voltage Vt. = 1) can be maintained for 0.6 seconds. As described above, since the sensing voltage Vk is set to the latest four average values when the measurement voltage Vn is input more than four times, the influence of noise can be eliminated. Furthermore, since the reference voltage Vt is the latest average value of 20 times when the input of the measurement voltage Vn exceeds 20 times, the reference voltage Vt can be changed following the change of the surrounding environmental conditions.

  Note that the number of measurement voltages Vn for obtaining the sensing voltage Vk, the reference voltage Vt, and the set value are, for example, how fast the measurement voltage changes, and whether the determination output is turned on or off. Can be determined. Here, when the measured voltage Vn changes at a speed of 1.5 mV / msec or more, the judgment output turns on within 100 msec (indicated by MAX100 in FIG. 7), turns off at 1 mV / msec or less, and 1 to 1.5 mV / msec is set to turn on after 100msec. Once the determination output is turned on, the on state is maintained for a predetermined time (here, 600 msec, indicated by MIN600 in FIG. 7) by the process of step S15.

  The determination output is turned on until the 40-second timer counted in step S18 elapses for 40 seconds (step S19: NO). Thereafter, if it is determined that 40 seconds have elapsed (step S19: YES), the determination is turned off (= 0), and both the 40-second timer and the 0.6-second timer are reset (= 0) (step S20). Since resetting is performed in a maximum of 40 seconds (indicated by MAX40000 in FIG. 7), the determination output of the microcomputer 13 is not maintained in the on state, and wasteful power consumption can be suppressed. For example, when heavy rain suddenly falls and the measured voltage is maintained at a high level, after the determination output is turned on continuously for 40 seconds, the state returns to the off state. Thereby, it can avoid that an ON state is maintained on conditions other than the case where a human body approaches the doorknob 1. FIG. Then, when the determination output is ON (= 1) in step S19 and the process returns to step S2, the determination output is ON (= 1) (step S2: YES), so the process proceeds to step S5 and enters the sleep mode. Will not enter. Thereby, the microcomputer 13 maintains the operating state, and the output of the ON signal from the output terminal GP2 of the microcomputer 13 is continued. On the other hand, when the process returns from step S20 to step S2 with the determination output being off (= 0), the determination output is off (= 0) (step S2: NO), so the process proceeds to step S3 and the sleep mode is entered. To continue the process.

  In the above embodiment, the sense voltage Vk and the reference voltage Vt are compared to determine whether or not the human body is approaching. However, the human body is directly compared with the measured voltage Vn and the reference voltage Vt. You may make it determine whether it approached.

  In the above embodiment, the reference voltage Vt is configured as an average value for the set number of times (20 times) from the latest among the past measurement voltages stored in the measurement voltage storage means, but is not limited thereto. For example, the average value for the set number of past measurement voltages may be used as the reference voltage more than the oldest measurement voltage used when calculating the measurement voltage or the sense voltage.

(A) is front sectional drawing which shows the state which employ | adopted the human body detection apparatus which concerns on this embodiment for the door knob of a vehicle, (b) is a top view. It is a disassembled perspective view of the human body detection apparatus which concerns on this embodiment. It is a circuit diagram in the printed circuit board of FIG. It is a flowchart figure which shows the human body determination process in the microcomputer of FIG. It is a flowchart figure which shows the human body determination process in the microcomputer of FIG. It is a graph which shows the input waveform and output waveform of the EXOR circuit of FIG. It is a graph which shows the relationship between the measurement voltage input into the microcomputer of FIG. 3, the reference voltage set in a microcomputer, and the output from a microcomputer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Door knob 2 ... Human body detection apparatus 3 ... Casing 4 ... 1st accommodation recessed part 5 ... Ferrite antenna 6 ... Antenna electrode 7 ... 2nd accommodation recessed part 8 ... Printed circuit board 9 ... Ferrite core 10 ... Electric wire 11 ... EXOR circuit 12 ... Integration circuit DESCRIPTION OF SYMBOLS 13 ... Microcomputer 14 ... Power supply circuit 15 ... Waveform generation part 16 ... Oscillation part 17 ... Reset part 18 ... Memory | storage part 19 ... Control part 20 ... ECU
21 ... Power supply IC

Claims (5)

Antenna means that is electrically connected to the antenna electrode, converts the capacitance of the antenna electrode into a voltage and outputs it as a measurement voltage;
Measurement voltage storage means for storing a measurement voltage output from the antenna means;
Among the past measurement voltages stored in the measurement voltage storage means, a sense voltage that is an average value for the first set number of times from the latest one, and a first set number of times from the latest value used when calculating the sense voltage. The human body approach determines whether or not the human body has approached the antenna electrode by comparing the reference voltage, which is the average value for the second set number of times, from the past measured voltage further than the oldest measured voltage of the measured value A determination means;
With
The human body detection apparatus characterized in that the first set number of times is less than the second set number of times.   The human body detection apparatus according to claim 1, further comprising an extraction timing adjustment unit that adjusts a cycle for extracting the measurement voltage.   3. The human body detection device according to claim 1, wherein the human body approach determination unit determines whether or not the human body has approached the antenna electrode at a constant time period, and sets the sleep mode in other cases. Timer means for measuring the elapsed time since the determination by the human body approach determination means is performed;
A determination result storage means for storing a determination result in the human body approach determination means until an elapsed time measured by the timer means passes a set time;
The human body detection device according to claim 1, further comprising: A voltage output step for outputting a measurement voltage based on the capacitance of the antenna electrode that changes due to the approach of the human body;
Comparing the measured voltage output in the voltage output step with a reference voltage for determining the approach of the human body, and satisfying the setting condition, thereby determining that the human body has approached the antenna electrode; and ,
A human body detection method including:
A measurement voltage storage step of storing the measurement voltage output in the voltage output step;
The human body approach determination step includes the latest measurement voltage stored in the measurement voltage storage step and the latest voltage used when calculating the detection voltage, which is an average value for the first set number of times from the latest one. Whether the human body has approached the antenna electrode by comparing the reference voltage, which is the average value of the second set number of times from the past measured voltage, than the oldest measured voltage of the measured value for the first set number of times A human body detection method characterized by determining whether or not.

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