JP3869781B2 - Object detection method and object detection apparatus - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an infrared detection type object detection method and apparatus, and more particularly to an infrared detection type object detection method and apparatus that can reduce erroneous detection due to background noise.
[0002]
[Prior art]
As shown in FIG. 7, the infrared type passive object detection apparatus condenses infrared rays emitted from a predetermined detection area by an optical system 101, and the fluctuation amount is converted by an infrared detection element 102 such as a pyroelectric sensor. When the value converted into the signal and amplified by the amplifier 103 reaches a certain level (threshold value), the level determination unit 104 determines that there is an object, and the control output unit 105 detects that the level determination unit 104 is an object. Some devices output an operation control output to various devices (not shown) when they are determined to be present.
[0003]
An operation example of such an infrared type object detection apparatus will be described with reference to FIGS. 8A is a diagram showing the output signal of the pyroelectric sensor when the apparatus of FIG. 7 is installed indoors and no human body is present in the detection area, and FIG. 8B is the apparatus of FIG. Is a diagram showing an output signal (including a detection signal) of a pyroelectric sensor when a human body is present in a detection area.
[0004]
When the pyroelectric sensor is used, the window center voltage Vwm and the window voltages (threshold values) Vwh and VwL are set, and the voltage level of the signal obtained by amplifying the output of the pyroelectric sensor is changed from the window center voltage Vwm to the window voltage Vwh or When the window voltage VwL is exceeded, the level determination unit 104 determines that there is an object. Therefore, in the state as shown in FIG. 8A, it is determined that there is no object, and in the state as shown in FIG. 8B, it is determined that there is an object based on the detection signal A that is output when a human body is detected.
[0005]
When such an infrared detection type object detection apparatus is installed outdoors, for example, fluctuations in the output of the infrared detection element due to changes in sunlight, changes in the temperature of the ground, ambient wind, etc. (hereinafter referred to as “background noise”) The object is erroneously detected. This will be described with reference to FIGS. 9 (a) and 9 (b). FIG. 9A is a diagram showing an output signal of the pyroelectric sensor when the apparatus of FIG. 7 is installed outside the daytime room and no human body is present in the detection area, and FIG. 9B is a diagram. 7 is a diagram showing an output signal of a pyroelectric sensor when the apparatus of No. 7 is installed outside the room during the day and a human body enters the detection area. As is clear from FIG. 9 (a), when an infrared detection type object detection device is installed outdoors, sunlight in the daytime, the ground whose temperature has risen, and the surrounding wind, even though no human body is present As a result, background noise occurs, the pyroelectric sensor output signal is unstable and fluctuates greatly, and there is an incorrect object despite the absence of a human body at X1 to X6 in the figure. Judgment is made. Moreover, even if there is actually a human body detection signal A as shown in FIG. 9B, the detection accuracy deteriorates because X1 to X6 exist.
[0006]
An infrared detection type object detection device that reduces the influence of the background noise is disclosed in, for example, Japanese Patent Application Laid-Open No. 8-178750 (Patent Document 1), Japanese Patent Application Laid-Open No. 9-33662 (Patent Document 2), and Japanese Patent Application Laid-Open No. 2000-206267. It describes in the gazette (patent document 3) and Unexamined-Japanese-Patent No. 2001-345187 (patent document 4). Hereinafter, these conventional techniques will be briefly described.
[0007]
In the first prior art described in Japanese Patent Laid-Open No. 8-178750, a thermistor is provided in addition to the infrared detection element, and the threshold value is changed based on the output of the thermistor.
[0008]
In the second prior art described in Japanese Patent Laid-Open No. 9-33662, the output of the infrared detection element is monitored every predetermined time, and if the output of the infrared detection element does not exceed the threshold at that time, the threshold is set. In this case, the output is sequentially changed to a value obtained by adding a predetermined value to the output of the infrared detecting element.
[0009]
In the third prior art described in Japanese Patent Laid-Open No. 2000-206267, an environmental light quantity light receiving unit is provided in addition to an object detection infrared sensor, and these outputs are compared to detect an object.
[0010]
In the fourth conventional technique described in Japanese Patent Laid-Open No. 2001-345187, particularly the technique described as the third embodiment, the H level period of the pulse signal output only during the period when the output of the infrared sensor exceeds the threshold value. It is determined whether or not the output of the infrared sensor is a background noise component based on whether or not a predetermined time is exceeded.
[0011]
[Patent Document 1]
JP-A-8-178750
[Patent Document 2]
JP 9-33662 A
[Patent Document 3]
JP 2000-206267 A
[Patent Document 4]
JP 2001-345187 A
[0012]
[Problems to be solved by the invention]
However, the first conventional technique has a problem that the structure becomes large because a thermistor is provided in addition to the infrared detection element. This problem is common to the third prior art in which the ambient light quantity light receiving unit is provided in addition to the object detection infrared sensor.
[0013]
Further, in the first conventional technique, the influence of the background noise is reduced by changing the threshold value based on the background temperature. However, the background noise having a large level exceeding the threshold value (for example, X1 in FIG. 9). When noise occurs, there is a problem of erroneous detection. The problem when a background noise with a large level exceeding the threshold value is generated is a problem common to the second prior art.
[0014]
In the fourth prior art, the output of the infrared sensor is based on whether or not the H level period of the pulse signal output during the period when the output of the infrared sensor exceeds the threshold exceeds a predetermined time. Therefore, as a countermeasure against the occurrence of a background noise having a large level exceeding the threshold, it is more advanced than the first conventional technique and the second conventional technique. Since the pulse signal that is output only during the period when the output exceeds the threshold value is used for determining the presence of the object, for example, when background noise with a long pulse width occurs as shown by X5 in FIG. There was a problem that there is a high possibility that it will end.
[0015]
An object of the present invention is to provide an object detection apparatus that can reduce the possibility of erroneous detection as much as possible even when background noise having a large level exceeding a threshold value occurs with a simple configuration. .
[0016]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a step of generating a detection output in accordance with a variation amount of infrared rays emitted from a predetermined detection area, and a second threshold value in which the detection output is smaller than the first threshold value and the first threshold value. The object detection method includes a step of counting the time continuously included between and a step of determining whether an object exists in the predetermined detection area based on the count value. According to such a method, there is no need for a dedicated element for detecting background noise as in the prior art, and the detection output corresponding to the fluctuation amount of infrared rays radiated from a predetermined detection area is the first. Since it is determined whether or not an object is present in a predetermined detection area based on the time continuously included between the threshold value and the second threshold value, for example, a background noise having a large level exceeding the threshold value is generated. In this case, the possibility of false detection can be reduced.
[0017]
According to a second aspect of the present invention, an infrared detection unit that generates a detection output corresponding to a variation amount of infrared rays emitted from a predetermined detection area, a first threshold value, and a second threshold value that is smaller than the first threshold value are set. A threshold value setting unit, a first counter unit that counts a time during which the detection output is continuously included between the first threshold value and the second threshold value, and the first counter unit. And a determination unit that determines whether an object is present in the predetermined detection area based on the count value. According to such a configuration, since a dedicated element for detecting background noise is not required as in the prior art, the configuration can be simplified, and the amount of infrared radiation radiated from a predetermined detection area can be reduced. Since it is determined whether or not an object exists in a predetermined detection area based on the time during which the corresponding detection output is continuously included between the first threshold value and the second threshold value, for example, the threshold value may be exceeded. When background noise with a large level is generated, the possibility of erroneous detection can be reduced.
[0018]
In a third invention, the determination unit determines whether or not an object exists in the predetermined detection area based on a comparison result between a count value of the first counter unit and a first desired value. The object detection apparatus further includes a first setting unit that sets the first desired value. According to such a configuration, the first desired value can be appropriately changed, the versatility regarding the environmental change is increased, and the operation reliability in outdoor use is increased.
[0019]
The fourth invention further includes a second counter unit that counts a time during which the detection output continuously exceeds the first threshold, and the determination unit includes the first counter unit and the second counter unit. It is a moving object detection device that determines whether a moving object exists in the predetermined detection area based on a count value. According to such a configuration, in addition to the above effects, the accuracy of object detection can be improved.
[0020]
According to a fifth aspect of the invention, the determination unit compares the count value of the first counter unit and the first desired value, and the comparison result of the count value of the second counter unit and the second desired value. The object detection apparatus further includes a second setting unit that sets the second desired value. According to such a configuration, the second desired value can be changed as appropriate, versatility with respect to environmental changes is increased, and operational reliability in outdoor use is increased.
[0021]
The sixth invention further includes a third counter unit that counts a time during which the detection output continues below the second threshold, and the determination unit includes the first and third counter units. It is an object detection device that determines whether an object exists in the predetermined detection area based on a count value. According to such a configuration, in addition to the above effects, the accuracy of object detection can be improved.
[0022]
In a seventh aspect of the invention, the determination unit includes a comparison result between the count value of the first counter unit and the first desired value, and a comparison result between the count value of the third counter unit and the third desired value. Whether or not an object is present in the predetermined detection area, and further includes a third setting unit for setting the third desired value. According to such a configuration, the third desired value can be appropriately changed, the versatility regarding the environmental change is increased, and the operation reliability in outdoor use is increased.
[0023]
An eighth invention further includes a third counter unit that counts a time during which the detection output continues to fall below the second threshold value in the fourth or fifth invention, and the determination unit includes the above-described determination unit, It is an object detection device that determines whether an object exists in the predetermined detection area based on the count values of the first, second, and third counter units. According to such a configuration, in addition to the above effects, the accuracy of object detection can be improved.
[0024]
In a ninth aspect of the invention, the determination unit includes a comparison result between the count value of the first counter unit and the first desired value, the count value of the second counter unit, and the second desired value. Based on the comparison result and the comparison result between the count value of the third counter unit and the third desired value, it is determined whether or not an object exists in the predetermined detection area. The object detection apparatus further includes a third setting unit for setting a value. According to such a configuration, the third desired value can be appropriately changed, the versatility regarding the environmental change is increased, and the operation reliability in outdoor use is increased.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described based on an example shown in the drawings.
[0026]
First, comparing the output waveform of the pyroelectric sensor with only background noise in FIG. 9A and the output waveform of the pyroelectric sensor in which background noise and detection signal A are mixed in FIG. Although the background noise of (a) has a high voltage level, the rising and falling edges of the voltage waveform show moderate characteristics. On the other hand, the waveform of the human body detection signal A in FIG. 9B is sharp at both the rising and falling edges, and shows a characteristic clearly different from the waveform of the background noise in FIG. 9A. Furthermore, when the waveform of FIG. 9B is compared with the waveform of FIG. 8B, the waveform of FIG. 9B is influenced by background noise, but a signal (detection signal A) at the time of human body detection is detected. ) Does not significantly impair the characteristics of the detection signal A in FIG.
[0027]
In this example, paying attention to the difference between these waveforms, the following processing is performed at the time of signal processing, thereby reducing the influence of background noise as much as possible and improving the detection accuracy of the detection signal of a desired object. Is.
[0028]
The outline of this example is that the presence of a moving object is determined based on whether or not the output of the infrared sensor has exceeded a predetermined threshold as in the prior art, and the time that the output of the infrared sensor has continuously exceeded the predetermined threshold. Rather than determining, the presence of the object is determined based on the time during which the output of the infrared sensor is continuously included between the two threshold values.
[0029]
FIG. 1 is a block diagram showing a circuit configuration and the like of an embodiment of the present invention. In the figure, an optical system 1 such as a lens collects infrared rays from a detection area a. The pyroelectric sensor 2 as an infrared detecting element receives the infrared rays collected by the optical system 1 and generates a detection output corresponding to the amount of fluctuation of the received infrared rays. The amplifying unit 3 amplifies the detection output of the pyroelectric sensor 2. The A / D converter 4 A / D converts the detection output of the pyroelectric sensor 2 amplified by the amplifier 3. The pyroelectric sensor 2, the amplifier 3, and the A / D conversion unit 4 constitute an infrared detection unit 5. When the amplifier 3 and the A / D conversion unit 4 are included in the same chip as the CPU 6, the infrared detection unit is the pyroelectric sensor 2. The CPU 6 as the determination unit performs various controls as described later using the RAM 8 and the timer 9 as the first to third counter units based on the operation program written in the ROM 7. In addition to the operation program, the ROM 7 as the threshold setting unit stores a window voltage upper limit Vwh as a first threshold and a window voltage lower limit VwL as a second threshold. The D / A converter 10 D / A converts the output of the CPU 6. The control output unit 11 generates a control output for controlling the operation of a device (not shown) (for example, a lighting device, a sound notification device, an alarm device, etc.) based on the output of the CPU 6 that has been D / A converted.
[0030]
Next, an outline of the operation will be described with reference to FIG. FIG. 2 is a diagram illustrating a detection output Vo when the infrared detection unit 5 detects a human body that is a detection target object. The detection target object is not limited to a human body and can be changed as appropriate. In this example, after the human body is detected and the detection output Vo rises, the time from when the window voltage upper limit Vwh is exceeded to when the detection output Vo ends after falling from the upper peak and falls below the window voltage upper limit Vwh. It is assumed that Th (see FIG. 2). Subsequently, the time from when the detection output Vo falls below the window voltage upper limit Vwh until it falls below the window voltage lower limit VwL is defined as Tm (see FIG. 2). That is, the time during which the detection output Vo is continuously included between two threshold values (the window voltage upper limit Vwh and the window voltage lower limit VwL) is defined as Tm. Furthermore, after the detection output Vo falls below the window voltage lower limit VwL, it rises again after finishing the lower peak, and the time from the detection output Vo exceeding the window voltage lower limit VwL is taken as TL (see FIG. 2).
[0031]
In this example, based on the lengths of these times Th, Tm, and TL, it is determined whether the change in the detection output of the infrared detection unit 5 is caused by background noise or the detection of an object to be detected. Thus, the deterioration of the object detection accuracy is suppressed.
[0032]
Next, the operation will be described with reference to FIG.
[0033]
When the object detection operation is started by power-on or reset input, the CPU 6 clears the stored contents of the time storage areas Th, Tm, and TL provided in the RAM 8 (step 3a).
[0034]
When the detection output Vo of the infrared detector 5 becomes Vo ≧ window voltage upper limit Vwh (step 3b), the CPU 6 starts the timer 9 and counts time Th until the detection output Vo falls below the window voltage upper limit Vwh (step 3b). 3c) When the detection output Vo falls below the window voltage upper limit Vwh (step 3d), the value of the timer 9 at that time is stored in the time storage area Th in the RAM 8, and the timer 9 is cleared.
[0035]
The CPU 6 proceeds to the next step 3f if the time Th ≧ T1 (in this example, T1 = 200 msec), and returns to step 3a if the time Th <T1 (step 3e). That is, when the time Th does not become T1 or more, it is determined that the current detection output Vo is a signal different from the desired signal (signal corresponding to the detection target). Therefore, a signal that slightly exceeds the window voltage upper limit Vwh and immediately falls below the window voltage upper limit Vwh can be recognized as noise, and the object detection accuracy can be prevented from being deteriorated by a signal different from the desired signal.
[0036]
When the time Th ≧ T1 in step 3e, the CPU 6 starts the timer 9 if the detection output Vo is Vo <window voltage upper limit Vwh (step 3f), and the time until the detection output Vo becomes the window voltage lower limit VwL or less. When Tm is counted (step 3g) and the detection output Vo falls below the window voltage lower limit VwL (step 3h), the value of the timer 9 at that time is stored in the time storage area Tm in the RAM 8 and the timer 9 is cleared. To do. If Vo <the window voltage upper limit Vwh is not satisfied in step 3f, it is determined that the current detection output Vo is noise (a signal different from the desired signal), and the process returns to step 3a.
[0037]
If the time Tm ≦ T2 (in this example, T2 = 400 msec), the CPU 6 proceeds to the next step 3j, and if the time Tm ≦ T2 is not satisfied, the detection output Vo of the infrared detector 5 returns to step 3a ( Step 3i). That is, when the time Tm does not become T2 or less, it is determined that the current detection output Vo is background noise or noise (a signal different from the desired signal), and the process returns to Step 3a. Therefore, it is possible to determine whether the detection output Vo is caused by the background noise or the detection target object by setting the time T2 to a time corresponding to the detection target object.
[0038]
When the time Tm ≦ T2 in step 3i, if the detection output Vo of the infrared detector 5 is Vo ≦ window voltage lower limit VwL (step 3j), the timer 9 is started and the detection waveform Vo exceeds the window voltage lower limit VwL. When the time TL is counted (step 3k) and the detected waveform Vo exceeds the window voltage lower limit VwL (step 3m), the value of the timer 9 at that time is stored in the time storage area TL in the RAM 8 and the timer 9 is cleared. To do. If Vo ≦ window voltage upper limit Vwh is not satisfied in step 3j, the current detection output Vo is determined to be noise, and the process returns to step 3a.
[0039]
When the time TL ≧ T3 (T3 = 200 msec in this example) is not satisfied, the CPU 6 returns to step 3a (step 3n). That is, when the time TL does not become T3 or more, it is determined that the current detection output Vo is noise. Therefore, it is possible to recognize as a noise a signal that is slightly below the window voltage lower limit VwL and immediately becomes equal to or higher than the window voltage lower limit VwL, and it is possible to prevent the object detection accuracy from being deteriorated by such noise.
[0040]
The CPU 6 determines that the detection target object exists in the detection area if the time TL ≧ T3, that is, the detection signal A shown in FIGS. 8B and 9B exists in the detection output Vo. An object detection signal is output (step 3p). The object detection signal output from the CPU 6 is D / A converted by the D / A conversion unit 10, and the control output unit 11 is based on the D / A converted object detection signal of the CPU 6 (not shown) (for example, an illumination device). And a control output for controlling the operation of the voice notification device, alarm device, etc.).
[0041]
As described above, since the object detection signal is output only when the times Th, Tm, and TL satisfy predetermined conditions, it is possible to suppress the deterioration of the accuracy of object detection.
[0042]
In addition, comparison values with the times Th, Tm, and TL used for background noise removal (in this example, T1 (first desired value), T2 (second desired value), T3 (third desired value)) And comparison conditions (in this example, Th ≧ T1, Tm ≦ T2, TL ≧ T3) are not limited to the above values, and can be changed as appropriate based on background noise, signal processing speed, response speed of the main circuit, and the like. is there. For example, an upper limit and a lower limit are set for all or part of Th, Tm, and TL depending on various environments. For example, 200 msec ≦ Th ≦ 800 msec, 200 msec ≦ TL ≦ 800 msec, and 100 msec ≦ Tm ≦ 400 msec are set as comparison conditions. You may make it the structure which raises detection accuracy, or you may set like Th> = 200msec, TL> = 200msec, 100msec <= Tm <= 400msec. Also in this case, these values can be appropriately changed.
[0043]
Further, the comparison values with the times Th, Tm, and TL used for background noise removal can be freely set, changed, and adjusted by providing the parameter external input unit 12 as a setting unit as shown in FIG. It becomes. In the case of such a configuration, the comparison value with the time Th, Tm and TL can be set, changed and adjusted according to the weather, the season, the surrounding environment of the installation location, etc. However, the comparison value can be set to a value according to the use environment of the apparatus, and a stable system can be realized. The parameter external input unit 12 may be configured such that a value can be directly input using an input means such as a keyboard, or a set value of a plurality of patterns is previously stored in a memory using a port input of a microcomputer or the like. A configuration may be prepared and the setting value may be switched according to the port input, and can be changed as appropriate. In FIG. 4, the same components as those in FIG. 1 are denoted by the same reference numerals.
[0044]
In the above example, all the times Th, Tm, and TL are determined to be background noise. However, only the times Th and Tm are determined to be background noise (see FIG. In the example of step 3, if step 3i is Yes, step 3p is executed, and steps 3j to 3n are not performed.) Only the time Tm and the time TL are determined whether or not it is background noise. (In the example of FIG. 3, when going directly from step 3a to step 3f and not performing step 3b to step 3e), the process of determining whether or not there is background noise only for time Tm (example of FIG. 3). In other words, go directly from step 3a to step 3f without performing step 3e from step 3b, and execute step 3p if step 3i is Yes. If you from 3j does not perform the step 3n.) It may be.
[0045]
In the above example, the detection output of the infrared detection unit 5 when detecting the detection target object is as shown in FIG. 2, but depending on the temperature of the detection target object and the way of entering the detection area, the detection target As shown in FIG. 5, the detection output of the infrared detection unit 5 when detecting an object may be reversed in the way of rising and falling as shown in FIG. In such a case, after performing step 3a in FIG. 3, first, the above-described noise determination processing for TL is performed, then the background noise determination processing for Tm as described above is performed, and finally for Th. The above-described noise determination process may be performed.
[0046]
Further, the background noise determination process for the time Tm may be performed both when the detection output as shown in FIG. 2 is output from the infrared detection unit 5 and when the detection output as shown in FIG. 5 is output. An example of this operation will be described with reference to FIG. The configuration in this case is the same as in FIG. 1 and FIG.
[0047]
When the object detection operation is started by power-on, reset input, or the like, the user inputs and sets comparison values Tin1 and Tin2 (first desired values) to be compared with the time Tm from the parameter external input unit 12 (step 1). 6a, 6b). When the configuration of FIG. 1 is adopted, these comparison values Tin1 and Tin2 are set in advance, and steps 6a and 6b are not performed.
[0048]
Subsequently, the CPU 6 clears the stored contents of the time storage area Tm provided in the RAM 8 (step 6c).
[0049]
When the detection output Vo of the infrared detector 5 is Vo ≧ window voltage upper limit Vwh (step 6d), the process waits until the detection output Vo becomes Vo <window voltage upper limit Vwh (step 6e).
[0050]
When the detection output Vo becomes Vo <window voltage upper limit Vwh (step 6e), steps 6f, 6g, and 6h similar to steps 3f, 3g, and 3h in FIG. 3 are performed. That is, the time Tm of the detection output having the shape shown in FIG. 2 is measured in steps 6f, 6g, and 6h.
[0051]
When the detection output Vo becomes Vo ≦ window voltage lower limit VwL in step 6h, the CPU 6 stores the value of the timer 9 at that time in the time storage area Tm in the RAM 8 to clear the timer 9, and the time Tm is Tin1 ≦ Tm. If ≦ Tin2 is not satisfied (step 6i), the process returns to step 6c. If the time Tm satisfies Tin1 ≦ Tm ≦ Tin2, it is determined that an object has been detected, and an object detection signal is output (step 6q). The object detection signal output from the CPU 6 is D / A converted by the D / A conversion unit 10, and the control output unit 11 is based on the output of the CPU 6 that has been D / A converted (for example, a lighting device or a voice). A control output for controlling the operation of a notification device, an alarm device or the like is output.
[0052]
On the other hand, if the detection output Vo is Vo <window voltage upper limit Vwh in step 6d, the CPU 6 determines whether or not the detection output Vo is Vo ≦ window voltage lower limit VwL (step 6j) and satisfies Vo ≦ window voltage lower limit VwL. If not, return to Step 6d.
[0053]
If Vo ≦ window voltage lower limit VwL is satisfied in step 6j, the operation shifts to the measurement operation of the detection output time Tm (the time during which the detection output is continuously included between the two threshold values) shown in FIG. . Specifically:
[0054]
Wait until the detection output Vo becomes Vo> window voltage lower limit VwL (step 6k).
[0055]
When the detection output Vo becomes Vo> window voltage lower limit VwL (step 6k), it is determined again whether the detection output Vo is Vo> window voltage lower limit VwL (step 6m). At this time, Vo> window voltage lower limit VwL. If not, the detection output at that time is determined to be noise, and the process returns to step 6c.
[0056]
If Vo> Window voltage lower limit VwL at Step 6m, the timer 9 is started, and the time Tm until the detection waveform Vo reaches the window voltage upper limit Vwh or more is counted (Step 6n), and the detection waveform Vo exceeds the window voltage upper limit Vwh. (Step 6p), the value of the timer 9 at that time is stored in the time storage area Tm in the RAM 8 to clear the timer 9, and the process proceeds to Step 6i to perform the above-described operation.
[0057]
Therefore, it is possible to determine whether or not the detection output Vo is background noise or other noise by setting the times Tin1 and Tin2 to the time corresponding to the detection target.
[0058]
In this example, Tin1 ≦ Tm ≦ Tin2 is used as the comparison condition for the time Tm, but the comparison condition is not limited to this and can be changed as appropriate.
[0059]
In addition, this invention is not limited only to the said Example, In the range which does not change a summary, it can deform | transform suitably and can be implemented.
[0060]
【The invention's effect】
According to the present invention, the predetermined detection is performed based on the time during which the detection output corresponding to the fluctuation amount of the infrared ray radiated from the predetermined detection area is continuously included between the first threshold value and the second threshold value. Since it is determined whether or not an object exists in the area, the possibility of erroneous detection can be reduced even if background noise with a large level exceeding a threshold value occurs, for example.
[Brief description of the drawings]
FIG. 1 is a block circuit diagram showing an embodiment of the present invention.
FIG. 2 is a waveform diagram showing an output waveform when the infrared detection unit 5 of FIG. 1 detects an object.
FIG. 3 is a flowchart for explaining the operation of FIG. 1;
FIG. 4 is a block diagram showing another embodiment of the present invention.
FIG. 5 is a waveform diagram showing an output waveform when the infrared detection unit 5 of FIG. 1 detects an object.
6 is a flowchart for explaining the operation of FIG. 4;
FIG. 7 is a block diagram showing a conventional object detection apparatus.
FIG. 8 is a waveform diagram showing an indoor output waveform of the infrared detection unit.
FIG. 9 is a waveform diagram showing an output waveform of the infrared detection unit outdoors.
[Explanation of symbols]
5 Infrared detector
6 judgment part
7 Threshold setting part
9 First, second and third counter units
12 1st, 2nd, 3rd setting part

Claims (9)

Generating a detection output corresponding to the amount of fluctuation of infrared rays emitted from a predetermined detection area;
Counting the time during which the detection output is continuously included between a first threshold and a second threshold that is smaller than the first threshold;
Determining whether an object exists in the predetermined detection area based on the count value. An infrared detector that generates a detection output corresponding to the amount of fluctuation of infrared rays emitted from a predetermined detection area;
A threshold setting unit in which a first threshold and a second threshold smaller than the first threshold are set;
A first counter unit that counts a time during which the detection output is continuously included between the first threshold value and the second threshold value;
And a determination unit that determines whether an object exists in the predetermined detection area based on a count value of the first counter unit. In Claim 2, the said determination part determines whether an object exists in the said predetermined detection area based on the comparison result of the count value of a said 1st counter part, and a 1st desired value. An object detection apparatus further comprising a first setting unit for setting the first desired value. 4. The method according to claim 2, further comprising a second counter unit that counts a time during which the detection output continues to exceed the first threshold, and the determination unit includes the first and second counter units. A moving object detection device that determines whether or not a moving object exists in the predetermined detection area based on the count value. The determination unit according to claim 4, wherein the determination unit includes a comparison result between the count value of the first counter unit and the first desired value, and a comparison result between the count value of the second counter unit and the second desired value. The object detection device further comprising: a second setting unit configured to determine whether or not an object exists in the predetermined detection area, and to set the second desired value. 4. The method according to claim 2, further comprising a third counter unit that counts a time during which the detection output continues below the second threshold value, and the determination unit includes the first and third counter units. An object detection device that determines whether or not an object exists in the predetermined detection area based on a count value. The determination unit according to claim 6, wherein the determination unit includes a comparison result between the count value of the first counter unit and the first desired value, and a comparison result between the count value of the third counter unit and the third desired value. The object detection apparatus further comprises a third setting unit for determining whether or not an object is present in the predetermined detection area, and setting the third desired value. 6. The method according to claim 4, further comprising a third counter unit that counts a time during which the detection output continues to fall below the second threshold, and the determination unit includes the first, second, and third counters. An object detection apparatus that determines whether or not an object exists in the predetermined detection area based on a count value of the counter unit. 9. The determination unit according to claim 8, wherein the determination unit compares the count value of the first counter unit with the first desired value, and compares the count value of the second counter unit with the second desired value. Based on the result and the comparison result between the count value of the third counter unit and the third desired value, it is determined whether or not an object exists in the predetermined detection area, and the third desired value is determined. An object detection apparatus further comprising a third setting unit for setting

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