JP2007114016A - Human body detecting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a human body detecting apparatus in detection accuracy, even when the ambient temperature is equal to or higher than the human body temperature. <P>SOLUTION: The human body detecting apparatus 3 comprises an infrared detector section 4; a first amplifier section (1) wherein the higher its temperature is, the higher its gain is set at a temperature lower than the prescribed value, determined as being approximate to the human body temperature; a second amplifier section (2), wherein the higher its temperature is, the lower its gain is set at the temperature equal to or higher than the prescribed value; a human body determining section 9 for determining as to whether an infrared emission object is a human body; a temperature-measuring section 7 for detecting the ambient temperature of a monitor area; and a switch circuit 5 and a switch control section 8 for switching over above two amplifier sections, according to the detected temperature. The sensitivity of detecting the human body becomes approximately constant, including the case where the ambient temperature is equal to or higher than the human body temperature, thereby improving the human body detecting apparatus in the detection accuracy. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a human body detection device that detects infrared rays emitted from a human body and determines the presence or absence of a human body in a monitoring area.

  2. Description of the Related Art Conventionally, a human body detection device that detects an intruder or the like by detecting infrared rays radiated from a human body using a differential pyroelectric element is known. Since this differential pyroelectric element is a sensor that detects the amount of infrared rays according to the temperature difference generated in the monitoring area, a signal from the pyroelectric element when the ambient temperature approaches the temperature of the human body to be detected. There is a disadvantage that the detection accuracy of a human body or the like decreases.

On the other hand, the detection device described in Patent Document 1 below includes an optical sensor that detects radiant energy, an arithmetic circuit that identifies the magnitude of the output change of the optical sensor, an alarm circuit that operates according to the output of the arithmetic circuit, A temperature sensor that detects the ambient temperature and a control circuit that increases the sensitivity of the arithmetic circuit or alarm circuit when the ambient temperature is high, and decreases the sensitivity of the arithmetic circuit or alarm circuit when the ambient temperature is low In contrast to the human body detection device, high detection accuracy is realized regardless of the ambient temperature.
JP-A-53-66199

  However, the detection device described in Patent Document 1 considers only when the ambient temperature is equal to or lower than the human body temperature. When the ambient temperature is equal to or higher than the human body temperature, the temperature difference between the two increases as the ambient temperature increases. Therefore, the detection accuracy was lowered.

  Also, the output signal of the pyroelectric element and the output signal of the temperature sensor that detects the ambient temperature are taken into the microcomputer, etc. via the A / D converter, respectively, and digital signal processing is performed to output the pyroelectric element according to the ambient temperature. There is also a human body detection device that adjusts the detection sensitivity of a signal change, but the power consumption of the A / D converter is relatively large and is not suitable for battery driving.

The present invention is intended to improve the detection accuracy of the human body detection device regardless of the ambient temperature, and in particular, to improve the detection accuracy of the human body detection device even when the ambient temperature is higher than the human body temperature. Objective.
Another object of the present invention is to reduce the power consumption of the human body detection device.

The human body detection device according to claim 1 is:
An infrared detector that detects an infrared ray change amount caused by an infrared radiation object in the monitoring area and outputs a detection signal according to the infrared ray change amount;
Regarding a predetermined temperature set near the temperature of the human body, a first amplification unit that amplifies and outputs the detection signal with a temperature characteristic having a higher amplification factor as the temperature is lower than the predetermined temperature,
A second amplifying unit that amplifies and outputs the detection signal with a temperature characteristic having a lower amplification factor as the temperature is higher than the predetermined temperature;
A determination unit that determines whether the infrared radiation object is a human body based on the detection signal;
A temperature measuring unit that outputs an output signal according to the ambient temperature of the monitoring area;
A path through which the output signal of the temperature measurement unit is input and the detection signal from the infrared detection unit is amplified by the first amplification unit and input to the determination unit if the ambient temperature is lower than the predetermined temperature A switching unit that selects a path for amplifying the detection signal from the infrared detection unit by the second amplification unit and inputting the detection signal to the determination unit if the ambient temperature is equal to or higher than the predetermined temperature;
It is characterized by having.

The human body detection device according to claim 2 is the human body detection device according to claim 1,
The switching unit is
The detection signal amplified from each of the first amplification unit and the second amplification unit is input, and from the detection signal from the first amplification unit or the second amplification unit by switching a switch And a switch circuit that configures the path by inputting any one of the detection signals to the determination unit.

The human body detection circuit according to claim 3 is the human body detection circuit according to claim 1,
The switching unit is
A switch circuit that receives the detection signal from the infrared detection unit and inputs the detection signal to either the first amplification unit or the second amplification unit by switching a switch to configure the path It is characterized by including.

The human body detection device according to claim 4 is the human body detection device according to any one of claims 1 to 3,
The determination unit includes a timing unit that starts measuring a predetermined determination period in order to determine whether the infrared radiation object is a human body when the level of the detection signal exceeds a predetermined level. ,
The switching unit prohibits the switching of the route during the time measurement by the time measuring unit.

The human body detection device according to claim 5 is the human body detection device according to claims 1 to 3,
The determination unit determines whether the infrared radiation object is a human body by comparing a level of the detection signal with a predetermined level,
The switching unit is characterized in that the switching of the path is prohibited when the level of the detection signal exceeds the predetermined level.

The human body detection device of the present invention is
An infrared detector that detects an infrared ray change amount caused by an infrared radiation object in the monitoring area and outputs a detection signal according to the infrared ray change amount;
Regarding a predetermined temperature set near the temperature of the human body, a first amplification unit that amplifies and outputs the detection signal with a temperature characteristic having a higher amplification factor as the temperature is lower than the predetermined temperature,
A second amplifying unit that amplifies and outputs the detection signal with a temperature characteristic having a lower amplification factor as the temperature is higher than the predetermined temperature;
By comparing the amplified detection signal input from the first or second amplification unit with a predetermined level, it is determined whether or not there is a level change due to an infrared radiation object, and an output signal according to the determination result An output level detection unit, a human body determination unit that outputs an output signal according to a determination result by determining presence or absence of a human body based on an output signal input from the level determination unit, and human body detection by the human body determination unit A time counting unit for measuring a predetermined time as a time required for the determination, and a determination unit for determining whether the infrared radiation object is a human body,
A temperature measuring unit that measures the ambient temperature of the monitoring area and outputs an output signal indicating whether the ambient temperature is equal to or higher than the predetermined temperature; and
If the ambient temperature is lower than the predetermined temperature, a path for amplifying the detection signal from the infrared detection unit by the first amplification unit and inputting the detection signal to the determination unit is configured, and the ambient temperature is equal to or higher than the predetermined temperature If so, a switch circuit constituting a path for amplifying the detection signal from the infrared detection unit by the second amplification unit and inputting the detection signal to the determination unit, and an ambient temperature output from the temperature measurement unit being a predetermined temperature A switching control unit that receives an output signal indicating whether or not the above and an output signal that indicates whether or not timing is being performed and is output from the timing unit, and outputs a control signal to the switch circuit based on these signals; By comprising a switching unit consisting of
The temperature characteristics of the first and second amplifiers are synthesized at the specified temperature. When the ambient temperature is lower than the specified temperature, the higher the ambient temperature, the higher the amplification factor of the infrared detection signal, and the ambient temperature matches the specified temperature. When the ambient temperature is higher than the specified temperature, the temperature characteristics can be realized such that the higher the ambient temperature is, the lower the amplification factor is, so that the ambient temperature is higher than the human body temperature. In addition, the detection accuracy of the human body can be improved by making the human body detection sensitivity substantially constant regardless of the ambient temperature, and the level determination unit prohibits the switching operation in the switch circuit during human body determination or when detecting an infrared radiation object. Since it is possible to configure the amplified signal input to the input signal so as not to be disturbed by the switching operation, the reliability of human body detection can be further improved.

  According to the human body detection device of the first aspect, the temperature characteristics of the first amplifying unit and the second amplifying unit are combined at a predetermined temperature that substantially matches the human body temperature. In other words, when the ambient temperature is lower than the predetermined temperature, the ambient temperature becomes higher, and the amplification factor of the infrared detection signal becomes higher.When the ambient temperature matches the predetermined temperature, the amplification factor becomes the highest, and the ambient temperature becomes the predetermined temperature. When it exceeds, the amplification factor decreases as the ambient temperature increases. For this reason, including the case where the ambient temperature is higher than or equal to the human body temperature, the sensitivity of human body detection becomes substantially constant regardless of the ambient temperature, and the detection accuracy of the human body detection device can be improved.

  According to the human body detection device according to claim 2, in particular, the amplified detection signal from the first amplifying unit and the second amplification are based on whether the ambient temperature is equal to or higher than a predetermined temperature (for example, human body temperature). The detection signal amplified from the unit can be switched by the switch circuit. That is, by the switching operation, an electrical path through which the detection signal is transmitted from the infrared detection unit to the level determination unit, a path through the first amplification unit when the ambient temperature is lower than the predetermined temperature, and the ambient temperature is equal to or higher than the predetermined temperature In such a case, it is possible to switch the path through the second amplifying unit, and the amplified detection signal selected thereby can be output to the determining unit.

  According to the human body detection device according to claim 3, the detection signal output from the infrared detection unit, in particular, based on whether or not the ambient temperature is equal to or higher than a predetermined temperature (for example, human body temperature), The second amplifying unit can be switched by a switch circuit. That is, by the switching operation, an electrical path through which the detection signal is transmitted from the infrared detection unit to the level determination unit, a path through the first amplification unit when the ambient temperature is lower than the predetermined temperature, and the ambient temperature is equal to or higher than the predetermined temperature In such a case, it is possible to switch the path through the second amplifying unit, and the amplified detection signal selected thereby can be output to the determining unit.

  According to the human body detection device of claim 4 and 5, particularly during the human body determination or when detecting the infrared radiation object, the switching operation in the switch circuit is prohibited and switched to the amplified signal input to the level determination unit. Since disturbance due to operation can be prevented, the reliability of human body detection can be improved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention that the patent applicant thinks best at the time of filing to implement the present invention will be described below.
1. Configuration of the first embodiment (FIGS. 1 to 3)
FIG. 1 is a block diagram showing the configuration of the human body detection device 3 according to the present embodiment, FIG. 2 is a diagram showing a graph of temperature characteristics of the first amplifying unit (1), and FIG. FIG. 6 is a graph showing a temperature characteristic of a part (2).

[Infrared detector 4]
The infrared detection unit 4 detects an infrared change amount generated by an infrared radiation object in the monitoring area, and an infrared detection signal corresponding to the infrared change amount is provided with a first amplification unit (1) and a second amplification unit (to be described later). Output to 2).

  The infrared detection unit 4 can be constituted by, for example, a differential pyroelectric sensor and a light collecting plate. In this case, the light collecting plate collects infrared rays into the pyroelectric sensor, and the pyroelectric sensor detects infrared rays at a level corresponding to the amount of infrared change. Output a signal. Here, the differential pyroelectric sensor can detect a spatial temperature difference in the monitoring area as a change in the amount of infrared rays from a temporal change by the differentiation circuit by a plurality of pyroelectric elements.

  Further, from the above principle, when the direction in which the infrared radiation object crosses the monitoring area is reversed, the positive / negative of the level of the infrared detection signal is reversed.

[First amplification section (amplification section (1))]
The amplifying unit (1) receives an infrared detection signal from the infrared detecting unit 4 and amplifies it, and outputs the amplified result as a first amplified signal to a switch circuit 5 described later, at least at a predetermined temperature. In the following, it has a temperature characteristic in which the amplification factor increases as the ambient temperature increases.

  The amplifying unit (1) can be configured as an amplifying circuit including, for example, an operational amplifier, a resistor, a thermistor, and a capacitor. The thermistor exhibits a temperature characteristic in which a resistance value decreases as the temperature rises, and the amplification factor of the amplifying circuit is determined by the resistance value. Therefore, if the thermistor is regarded as a variable resistor whose resistance value changes depending on the temperature, an amplifier having the above characteristics in which the gain increases as the temperature increases can be obtained by connecting the thermistor in series with the resistor on the input side. it can.

The predetermined temperature is set to 35 ° C., which is substantially the human body temperature in this example, and a desired gain can be obtained by selecting a resistor. FIG. 2 shows the temperature characteristics of the amplifying unit (1). T in the figure is the predetermined temperature (for example, 35 ° C.).
Note that a differential amplifier circuit including a transistor may be used instead of the operational amplifier.

[Second amplification section (amplification section (2))]
The amplifying unit (2) receives the infrared detection signal from the infrared detecting unit 4, amplifies it, and outputs the amplified result to the switch circuit 5 described later as a second amplified signal, at least at a predetermined temperature. The above has a temperature characteristic that the amplification factor decreases as the ambient temperature increases.

  The amplifying unit (2) can be configured as an amplifying circuit including, for example, an operational amplifier, a resistor, a thermistor, and a capacitor. The thermistor exhibits a temperature characteristic in which a resistance value decreases as the temperature rises, and the amplification factor of the amplifying circuit is determined by the resistance value. Therefore, if the thermistor is regarded as a variable resistor whose resistance value changes depending on the temperature, if the thermistor is connected in series to the resistance on the negative feedback side, the amplifier having the above characteristics can be obtained in which the amplification factor decreases as the temperature increases. it can.

The predetermined temperature is set to 35 ° C., which is substantially the human body temperature in this example, and a desired gain can be obtained by selecting a resistor. FIG. 3 shows the temperature characteristics of the amplification section (2). T in the figure is the predetermined temperature (for example, 35 ° C.).
Note that a differential amplifier circuit including a transistor may be used instead of the operational amplifier.

[Switch circuit 5] (one component of the switching unit)
The switch circuit 5 is constituted by a 2-input 1-output relay switch. An amplifying unit (1) and an amplifying unit (2) are connected to the input side, and a level discriminating unit 6 described later is connected to the output side. Further, a switching control unit 8 described later is connected and a control signal is input from the switching control unit 8.

  As will be described later, this control signal changes to L level when the ambient temperature is lower than the human body temperature, and to H level when the ambient temperature is higher than the human body temperature. The switch circuit 5 switches the switch according to the control signal, and selectively outputs one of the signals from the input side to the output side. That is, when an L level control signal is input, an electric path for connecting the input side to which the amplifier (1) is connected and the output side to guide the first amplified signal to the level determining unit 6 is formed. When a level control signal is input, an electrical path is formed that connects the input side to which the amplifier (2) is connected and the output side to guide the second amplified signal to the level discriminating unit 6.

[Level discriminating unit 6] (one component of the judging unit)
The level discriminating unit 6 receives the first amplified signal or the second amplified signal from the switch circuit 5, and compares these signals with a predetermined level to determine whether or not there is a level change due to the infrared radiation object. It discriminate | determines and outputs the output signal according to the discrimination | determination result to the human body determination part 9 mentioned later. This predetermined level is determined in advance by experiments so that the level indicated by the amplified signal can be discriminated from the level due to noise or the like when the infrared detector 4 detects a human body.

  The level discriminating unit 6 can be composed of a comparison circuit (analog circuit) including a comparator overnight. By configuring this part with an analog circuit (consumption current number μA), it is not necessary to A / D convert the detection signal (consumption current number mA) and input it to the microcomputer, thereby reducing the power consumption of the human body detection device. be able to.

  In the present embodiment, the level determination unit 6 includes two comparison circuits, and the output of each comparison circuit is output to the human body determination unit 9 described later. One comparison circuit has a predetermined level set to a positive level (V +), and outputs an H level signal indicating detection of an infrared emitting object when the amplified signal is equal to or higher than the predetermined level, and otherwise, it is at the L level. Output a signal. The other comparison circuit has a predetermined level set to a negative level (V-), and outputs an H level signal indicating infrared radiation object detection when the amplified signal falls below the predetermined level; otherwise, the L level. The signal is output.

[Temperature measurement unit 7]
The temperature measurement unit 7 measures the ambient temperature and outputs a signal indicating whether the ambient temperature is equal to or higher than the predetermined temperature (35 ° C.) to the switching control unit 8 described later. The temperature measurement unit 7 of this example is configured by a comparison circuit (analog circuit) including a thermistor and a comparator, and, like the level determination unit 6, reduces the power consumption of the human body detection device. The thermistor outputs a signal of a level corresponding to the ambient temperature to the comparison circuit. The comparison circuit outputs an H level output signal if the level of this signal is equal to or higher than the predetermined temperature, otherwise An L level output signal is output.

[Switching control unit 8] (one component of the switching unit)
The switching control unit 8 receives an output signal indicating whether or not the ambient temperature is equal to or higher than a predetermined temperature from the temperature measurement unit 7, and an output signal indicating whether or not timing is being performed from the timing unit 10 described later. Based on these signals, the switching control unit 8 outputs a control signal to the switch circuit 5.

  Specifically, the signal from the temperature measuring unit 7 is periodically monitored, and when the L level signal indicating that the ambient temperature is less than a predetermined temperature is input from the temperature measuring unit 7, the first is input to the switch circuit 5. L level signal indicating that the amplified signal is to be selected is output, and when the H level signal indicating that the ambient temperature is equal to or higher than the predetermined temperature is input from the temperature measuring unit 7, the second signal is input to the switch circuit 5. An H level signal indicating that the amplified signal should be selected is output.

  When an H level signal indicating that the time is being measured is input from the time measuring unit 10, the signal from the temperature measuring unit 7 is not monitored. That is, while the time measuring unit 10 is measuring time, the change of the control signal according to the ambient temperature is prohibited, and thus the switching of the electrical path by the switch circuit 5 is not performed.

[Human body determination unit 9] (one component of the determination unit)
The human body determination unit 9 receives from the level determination unit 6 an output signal corresponding to the determination result regarding the presence or absence of a level change due to an infrared radiation object, and also indicates whether the time measurement unit 10 is timing. A signal is input. The human body determination unit 9 determines the presence or absence of a human body based on these signals, and outputs an output signal corresponding to the determination result to the output unit 11 described later. Moreover, the timing start / time stop of the timing unit 10 is controlled in accordance with the determination operation.

  The determination is performed by detecting the change pattern of the infrared detection signal, and the human body is detected when a change on the positive level side appears a plurality of times within a predetermined time or when a change on the negative level side appears a plurality of times within a predetermined time. It shall be detected. Specifically, the following processing is performed.

  When an H-level output signal indicating infrared radiation object detection is input from the level discriminating unit 6, it is possible to distinguish whether the signal is due to a change on the positive level side or a change on the negative level side, and The timer unit 10 is instructed to start timing. When an H level signal whose direction coincides with the change being held is input again from the level determination unit 6 while the timing unit 10 is measuring the predetermined time, it is determined that the human body has been detected and is output to the output unit 11. While outputting an H level signal (human body detection signal), the timer unit 10 is instructed to stop timing, and the held signal is erased. When the timer 10 finishes counting the predetermined time without detecting the human body, the held signal is deleted and the determination is terminated.

[Timekeeping unit 10] (one component of the determination unit)
The timekeeping unit 10 is a timer that times a predetermined time that is predetermined as a time required for determination of human body detection. The time measuring unit 10 is instructed by the human body determining unit 9 to start measuring time, and starts measuring time for a predetermined time. The timekeeping unit 10 stops timekeeping when it finishes measuring the predetermined time and when the human body determination unit 9 is instructed to stop timekeeping. The time measuring unit 10 outputs an H level signal to the human body determination unit 9 and the switching control unit 8 during time measurement and an L level signal during non-time measurement.

[Output unit 11]
The output unit 11 is configured by a circuit that receives a human body detection signal from the human body determination unit 9 and sends it to the outside.

[Power supply 12]
The power source 12 is composed of a battery that supplies power to the human body detection device. By using a battery, a power cord connected to the external power source 12 becomes unnecessary, and the installation of the human body detection device 3 is improved.

  In the configuration of the human body detection apparatus described above, the part that functions as a determination unit that determines whether the infrared radiation object is a human body based on the detection signal output from the infrared detection unit 4 is the level determination unit 6. The human body determination unit 9 and the time measuring unit 10 are configured. Further, based on the detection result of the temperature measurement unit 7, the part that functions as a switching unit that appropriately switches between the two amplification units and inputs an appropriate amplification signal to the determination unit includes the switch circuit 5 and the switching control unit. 8.

  Regardless of the functional configuration, the switching control unit 8, the human body determination unit 9, and the time measuring unit 10 can be configured by a microcomputer, IC, or the like.

2. Operation of the first embodiment (FIG. 4)
FIG. 4 is a timing chart showing the operation of the human body detection device 3 according to the present embodiment, and shows the timings of the following signals.
Infrared detection signal output from the infrared detection unit 4 Output signal (+ and-) of the level determination unit 6
Output signal of timer unit 10 Monitoring timing signal indicating the timing at which switching control unit 8 monitors the output signal of temperature measuring unit 7 Output signal of temperature measuring unit 7 Control signal which is an output signal of switching control unit 8 Output signal (human body detection signal)
In the following, the operation of the present apparatus will be described in time series by indicating the timing with a symbol such as t1 on the time axis (horizontal axis) in FIG.

[~ Tl (absence of infrared radiation object, ambient temperature less than 35 ℃)]
In a state where there is no infrared radiation object in the monitoring area, the infrared detection signal is at a level close to 0, and the level determination unit 6 outputs an L level signal indicating the absence of the infrared radiation object. At this time, the timer unit 10 outputs an L level signal indicating that the timer is not counting.

  The temperature measuring unit 7 always measures the ambient temperature, and the switching control unit 8 monitors the output signal of the temperature measuring unit 7 at a predetermined timing. When the ambient temperature is less than 35 ° C. and the temperature measurement unit 7 outputs an L level signal, the switching control unit 8 outputs an L level control signal indicating the selection output of the first amplification signal. The switch circuit 5 receiving this control signal is in a state of outputting the first amplified signal to the level discriminating unit 6.

[Tl to t3 (ambient temperature rise)]
When the ambient temperature rises to 35 ° C. or higher, the output signal of the temperature measuring unit 7 changes from L level to H level. In FIG. 4, this timing is indicated by t1.

  The switching control unit 8 outputs an H level control signal representing the selection output of the second amplified signal to the switch circuit 5 in response to the output signal of the temperature measurement unit 7 being at the H level at the monitoring timing t2 immediately after this. To do.

  Upon receiving this signal, the switch circuit 5 is switched to a state in which the second amplified signal is output to the level determination unit 6 by the switch operation.

[T3-t4 (infrared radiation object intrusion, ambient temperature drop)]
When an infrared radiation object enters the monitoring area and a large level change occurs in the infrared detection signal output from the infrared detection unit 4, the level determination unit 6 sends an H level signal indicating infrared radiation object detection to the human body determination unit 9. Is output. In FIG. 4, this timing is indicated by t3.

  Upon receiving this signal, the human body determination unit 9 retains information that a positive level change has occurred, and transmits a command to start time measurement to the time measurement unit 10. Upon receiving the command, the timer unit 10 starts timing, and outputs an H level signal to the human body determination unit 9 and the switching control unit 8 during timing.

  Thereafter, while the time measuring unit 10 is measuring time, the switching control unit 8 ignores the output signal of the temperature measuring unit 7 assuming that the human body is being determined (switching by the switch circuit 5 is prohibited). In the example of FIG. 4, the ambient temperature falls below 35 ° C. at the timing t4 and the output of the temperature measuring unit 7 changes to the L level, but the switching control unit 8 ignores this.

[T5 to t6 (time up)]
In the example of FIG. 4, after the timing t3, the timing unit 10 finishes measuring the predetermined time without causing a large change in the infrared detection signal, and the output signal of the timing unit 10 changes to the L level at the timing t5. . When detecting the end of time measurement, the human body determination unit 9 deletes the stored information and ends the human body determination. Moreover, the switching control part 8 will restart monitoring of the temperature measurement part 7, if the time measurement end is detected.

  The switching control unit 8 is an L level signal that represents the selection output of the first amplified signal to the switch circuit 5 in response to the output signal of the temperature measurement unit 7 being at the L level at timing t6 immediately after the monitoring is resumed. The switch circuit 5 that receives this signal switches to a state in which the first amplified signal is output to the level discriminating unit 6.

[T7 to t8 (ambient temperature rise)]
When the ambient temperature rises again and becomes 35 ° C. or higher at timing t7, the output signal of the temperature measuring unit 7 changes from L level to H level, and at the monitoring timing t8 immediately after this, the switching control unit 8 becomes H level. The signal is output to the switch circuit 5, and the switch circuit 5 receiving this signal switches to a state in which the second amplified signal is output to the level determination unit 6.

[T9 to tlO (infrared radiation object intrusion, ambient temperature drop)]
When the infrared radiation object enters the monitoring area again at timing t9 and a large positive level change occurs in the infrared detection signal that exceeds (exceeds) the threshold value V +, the level determination unit 6 sends the infrared radiation object to the human body determination unit 9. An H level output signal (+) signifying detection is output.

  Upon receiving this signal, the human body determination unit 9 holds information that a positive level change has occurred, and transmits a command to start timing to the timing unit 10. The timer unit 10 that has received the instruction starts timing and starts outputting an H level signal to the human body determination unit 9 and the switching control unit 8.

  After that, at timing t10, the ambient temperature falls below 35 ° C. and the output of the temperature measuring unit 7 changes to L level. However, since the time measuring unit 10 is measuring time, that is, during human body determination, the switching control unit 8 Is ignored (switching by the switch circuit 5 is prohibited).

[Tll to t13 (human body detection)]
At timing t11, the infrared radiation object moves to cause a large change in the negative level that exceeds (below) the threshold value V− in the infrared detection signal, and the level determination unit 6 causes the human body determination unit 9 to detect infrared radiation object. Output signal (−) is output, but since the human body determination unit 9 does not match the stored information, the determination of human body detection is continued.

  At timing t12, the infrared radiation detection object moves again to cause a large positive level change in the infrared detection signal, and the level determination unit 6 outputs an H level output signal (+) indicating infrared radiation object detection to the human body determination unit 9. Then, the human body determination unit 9 determines that the human body is detected because it matches the information held.

  The human body determination unit 9 outputs a human body detection signal to the output unit 11, and the output unit 11 that has received this signal outputs a human body detection signal to the outside. In addition, the human body determination unit 9 transmits a time-end command to the time-measurement unit 10, and the time-measurement unit 10 that has received this command ends time-measurement. Furthermore, the human body determination unit 9 deletes the stored information.

  The switching control unit 8 resumes monitoring of the temperature measuring unit 7 when the time measuring unit 10 is not measuring time, and switches according to the output signal of the temperature measuring unit 7 being L level at the monitoring timing t13 immediately after the restart. An L level signal representing the selection output of the first amplified signal is output to the circuit 5, and the switch circuit 5 receiving this signal switches to a state of outputting the first amplified signal to the level determining unit 6. .

3. Other Embodiments In the first embodiment, the switch circuit 5 has been described as a switch circuit with two inputs and one output. However, a switch circuit with one input and two outputs is adopted as the switch circuit 5, and the infrared detector 4 is connected to the input side. Then, the amplification unit (1) and the amplification unit (2) may be connected to the output side. In this case, the switch circuit 5 forms an electrical path for guiding the infrared detection signal from the infrared detection unit 4 to either the amplification unit (1) or the amplification unit (2) by switching the switch. That is, when the switch circuit 5 receives an L level signal indicating that the first amplification signal should be selected from the switching control unit 8, the switching circuit 5 divides the input side from the output side connected to the amplification unit (1). When an H level signal indicating that the second amplification signal should be selected is input from the switching control unit 8, the input side and the output side connected to the amplification unit (2) are connected. The outputs of the amplifying unit (1) and the amplifying unit (2) are input to the level determining unit 6 through an OR gate.

  In addition, an example in which the switching control unit 8 inputs the output signal of the time measuring unit 10 to the switching control unit 8 in order to determine whether or not the human body determination unit 9 is performing human body determination has been described. May output a signal indicating whether or not a human body is being determined, and the switching control unit 8 may determine this by inputting this signal.

  Further, during the time measurement by the time measuring unit 10, the switching control by the switching control unit 8 is prohibited because the human body is being determined. However, the switching control is prohibited when the level determination unit 6 detects an infrared radiation object. May be. In this case, the switching control unit 8 receives a signal from the level determination unit 6 instead of the signal from the time measuring unit 10, and does not monitor the signal from the temperature measurement unit 7 when this signal is at the H level.

4). Effects According to the above embodiments of the present invention, the following effects can be obtained.
The temperature characteristics of the amplifying unit (1) and the amplifying unit (2) are synthesized at a predetermined temperature that substantially matches the human body temperature. In other words, when the ambient temperature is lower than the predetermined temperature, the higher the ambient temperature, the higher the amplification factor of the infrared detection signal. When the ambient temperature matches the predetermined temperature, the amplification factor becomes the highest. When the ambient temperature is higher, the gain is lower.

  Therefore, according to the human body detection device 3, the human body detection sensitivity is substantially constant regardless of the ambient temperature, including the case where the ambient temperature is higher than the human body temperature, and the human body detection accuracy can be improved.

  Furthermore, during human body determination or when detecting an infrared radiation object, the switching operation in the switch circuit 5 can be prevented so that the amplification signal input to the level determination unit 6 can be prevented from being disturbed by the switching operation. The reliability of human body detection can be further improved.

FIG. 1 is a block diagram showing a configuration of a human body detection device 3 according to the first embodiment of the present invention. FIG. 2 is a graph showing a temperature characteristic of the first amplifying unit (1) in the same embodiment. FIG. 3 is a graph showing a temperature characteristic of the second amplifying unit (2) in the same embodiment. FIG. 4 is a diagram showing a timing chart of the human body detection device 3 according to the embodiment.

Explanation of symbols

(1)… First amplifier
(2) ... 2nd amplification part 3 ... Human body detection apparatus 4 ... Infrared detection part 5 ... Switch circuit 6 ... Level discrimination part 7 ... Temperature measurement part 8 ... Switching control part 9 ... Human body determination part 10 ... Time measuring part 11 ... Output Part 12: Power supply

Claims (5)

An infrared detector that detects an infrared ray change amount caused by an infrared radiation object in the monitoring area and outputs a detection signal according to the infrared ray change amount;
Regarding a predetermined temperature set near the temperature of the human body, a first amplification unit that amplifies and outputs the detection signal with a temperature characteristic having a higher amplification factor as the temperature is lower than the predetermined temperature,
A second amplifying unit that amplifies and outputs the detection signal with a temperature characteristic having a lower amplification factor as the temperature is higher than the predetermined temperature;
A determination unit that determines whether the infrared radiation object is a human body based on the detection signal;
A temperature measuring unit that outputs an output signal according to the ambient temperature of the monitoring area;
A path through which the output signal of the temperature measurement unit is input and the detection signal from the infrared detection unit is amplified by the first amplification unit and input to the determination unit if the ambient temperature is lower than the predetermined temperature A switching unit that selects a path for amplifying the detection signal from the infrared detection unit by the second amplification unit and inputting the detection signal to the determination unit if the ambient temperature is equal to or higher than the predetermined temperature;
A human body detection device comprising: The switching unit is
The detection signal amplified from each of the first amplification unit and the second amplification unit is input, and from the detection signal from the first amplification unit or the second amplification unit by switching a switch 2. The human body detection device according to claim 1, further comprising a switch circuit configured to input one of the detection signals to the determination unit and configure the path. The switching unit is
A switch circuit that receives the detection signal from the infrared detection unit and inputs the detection signal to either the first amplification unit or the second amplification unit by switching a switch to configure the path The human body detection device according to claim 1, comprising: The determination unit includes a timing unit that starts measuring a predetermined determination period in order to determine whether the infrared radiation object is a human body when the level of the detection signal exceeds a predetermined level. ,
The human body detection device according to claim 1, wherein the switching unit prohibits the switching of the path during the time counting by the time measuring unit. The determination unit determines whether the infrared radiation object is a human body by comparing a level of the detection signal with a predetermined level.
The human body detection device according to claim 1, wherein the switching unit prohibits switching of the path when the level of the detection signal exceeds the predetermined level.

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