JP2001171476A - Starting device for occupant crash protection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To start an occupant crash protection device at appropriate timing. SOLUTION: The difference between acceleration G1 and acceleration G2 detected by two acceleration sensors arranged at the front of a vehicle linearly parallel with a proceeding direction is time-integrated to compute the deformation speed V of the front part of the vehicle (S110, S112). When the deformation speed V is the threshold Vref or more, a pattern of the threshold TH2 obtained by the downward correction of a pattern of the threshold TH1 which is default, is set as the threshold TH for determining the start timing of the occupant crash protection device. Since the deformation speed V is supposed to indicate the grade of impact and the severity of impact applied to the vehicle, when the deformation speed V is high, the threshold TH is made small to expedite the start timing of the occupant crash protection device, which results in starting the occupant crash protection device at appropriate timing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a starting device for an occupant protection device, and more particularly, to a starting device for an occupant protection device for starting an occupant protection device for protecting an occupant against an impact on a vehicle.

[0002]

2. Description of the Related Art Hitherto, as an activation device for an occupant protection device of this type, an occupant protection device which reduces a threshold value for determining the activation timing of the occupant protection device when an impact of a predetermined value or more is applied in front of a vehicle has been proposed. (See, for example,
No. 152014). In this device, a sensor that outputs an ON signal when an impact equal to or greater than a predetermined reference value is applied is mounted in front of the vehicle, and a threshold value that determines the activation timing of the occupant protection device based on whether the signal from this sensor is an ON signal or not. To change. Then, the occupant protection device is activated when the acceleration detected by the acceleration sensor disposed in front of the passenger compartment of the vehicle or the integrated value thereof reaches a threshold.

[0003]

However, such an activation device for an occupant protection device only changes the threshold value depending on whether or not an impact greater than a reference value is applied to the front of the vehicle. It may not be the one that is running.

An object of the present invention is to activate an occupant protection device at a more appropriate timing.

[0005] As an apparatus for solving the above-mentioned problem, there has been proposed an apparatus which sets a threshold value for deciding the activation timing of the occupant protection device based on the magnitude of an impact acting in front of the vehicle (Japanese Patent Application No. 2002-287686). Hei 10-326742).

[0006]

Means for Solving the Problems and Action / Effect Thereof The starting device of the occupant protection device of the present invention employs the following means in order to achieve the above object.

A first activating device for an occupant protection device according to the present invention is a activating device for an occupant protection device for activating an occupant protection device for protecting an occupant against an impact on a vehicle, wherein First acceleration detecting means for detecting acceleration due to the shock, deformation speed detecting means for detecting a deformation speed ahead of the vehicle due to the shock, and threshold setting for setting a threshold based on the detected deformation speed And an activation unit that activates the occupant protection device based on the acceleration detected by the first acceleration detection unit and a threshold set by the threshold setting unit.

In the first occupant protection device activation device of the present invention, the threshold value setting means sets the threshold value based on the deformation speed ahead of the vehicle due to the impact detected by the deformation speed detection means, and the activation means comprises: The occupant protection device is activated based on the acceleration detected by the first acceleration detection means and the threshold value set by the threshold value setting means. Since the deformation speed in front of the vehicle is considered to represent the magnitude of the impact and the severity of the impact, the threshold for determining the activation timing of the occupant protection device is set based on this, so that the occupant protection device can be further improved. It can be started at the right time.

In the first occupant protection device starting device of the present invention, the first occupant protection device further includes a second acceleration detecting means which is disposed in front of the vehicle with respect to the first acceleration detecting means and detects an acceleration due to the impact. A speed detection unit configured to determine, based on the acceleration detected by the first acceleration detection unit and the acceleration detected by the second acceleration detection unit, a position at which the first acceleration detection unit is disposed; It is also possible to calculate the relative speed with respect to the position where the acceleration detecting means is disposed, and to detect the calculated relative speed as the deformation speed in front of the vehicle. In this case, the deformation speed in front of the vehicle can be accurately detected based on the acceleration detected by the acceleration detecting means disposed in front of and behind the vehicle. In the activation device for a first occupant protection device according to the aspect of the present invention, the first acceleration detection means is disposed near a front center of an occupant compartment of the vehicle, and the second acceleration detection means is The deformation speed detecting means is located near the front center of the vehicle, and the deformation speed detecting means calculates a time integration of a deviation between the acceleration detected by the first acceleration detecting means and the acceleration detected by the second acceleration detecting means. It may be a means for calculating the relative speed.

[0010] In the starter of the first occupant protection device according to the present invention, the threshold value setting means may set a smaller threshold value as the detected deformation speed increases. In this case, the occupant protection device can be quickly activated in response to an impact having a high deformation speed. In the activation device for a first occupant protection device according to the aspect of the present invention, the threshold value setting means has a plurality of threshold values prepared in advance, and the higher the detected deformation speed is, the more the threshold value is set. It may be a means for selecting and setting a small threshold value.

Further, in the starter of the first occupant protection device according to the present invention, the starter means sets an integral period from the start of detection of the impact of the acceleration detected by the first acceleration detector to the present time. The occupant protection device may be a means for activating the occupant protection device when a time integration value having a predetermined time up to the present time of the acceleration with respect to the time integration value as an integration section reaches the set threshold value.

According to a second aspect of the present invention, there is provided a starting device for an occupant protection device for activating an occupant protection device for protecting an occupant against an impact on a vehicle. A first acceleration detecting means arranged to detect an acceleration due to the shock, a deformation amount detecting means to detect a deformation amount in front of the vehicle due to the shock, and the detected deformation amount and the first acceleration detecting means. The gist of the invention is to include a starting unit that starts the occupant protection device based on the detected acceleration and a predetermined threshold.

In the starting device for the occupant protection device according to the second aspect of the present invention, the deformation detecting means detects the amount of deformation in front of the vehicle due to the impact, and the starting means determines the amount of deformation in front of the vehicle and a predetermined position of the vehicle. Then, the occupant protection device is activated based on the acceleration due to the impact detected by the first acceleration detection means disposed at a predetermined threshold value. Since the occupant protection device is activated based on the amount of deformation in front of the vehicle, the occupant protection device can be activated at a more appropriate timing.

[0014] In the starting device for the second occupant protection device according to the present invention, there is provided the second acceleration detecting means which is disposed in front of the vehicle from the first acceleration detecting means and detects acceleration due to the impact, and The amount detecting means is configured to detect the acceleration detected by the first acceleration detecting means and the second acceleration.
The position where the first acceleration detecting means is arranged and the second position based on the acceleration detected by the acceleration detecting means.
May be a means for calculating a relative movement amount with respect to the position where the acceleration detecting means is disposed, and detecting the calculated relative movement amount as the deformation amount in front of the vehicle. In this case, the amount of deformation in front of the vehicle can be detected based on the acceleration detected by the acceleration detecting means disposed in front of and behind the vehicle. In the starting device for a second occupant protection device according to the aspect of the present invention, the first acceleration detecting means is disposed near a front center of an occupant compartment of the vehicle, and the second acceleration detecting means is provided for the vehicle. The deformation amount detecting means is located near the front center, and the deformation amount detecting means calculates the second order time integral of a deviation between the acceleration detected by the first acceleration detecting means and the acceleration detected by the second acceleration detecting means. It may be a means for calculating the relative movement amount.

Further, in the starting device of the second occupant protection device of the present invention, the starting means is detected by the first acceleration detecting means with respect to the deformation amount up to the present time detected by the deformation amount detecting means. The occupant protection device may be a means for activating the occupant protection device when a time integration value having a predetermined time up to the present time of the acceleration as an integration section reaches the predetermined threshold.

Further, in the starting device of the second occupant protection device according to the present invention, a deformation speed detecting means for detecting a deformation speed ahead of the vehicle due to the impact, and a threshold value for setting a threshold value based on the detected deformation speed. Setting means, and the activation means may be means for activating the occupant protection device using a threshold set by the threshold setting means instead of the predetermined threshold. Since the deformation speed in front of the vehicle is considered to represent the magnitude of the impact and the severity of the impact, the threshold for determining the activation timing of the occupant protection device is set based on this, so that the occupant protection device can be further improved. It can be started at the right time.

[0017]

Next, embodiments of the present invention will be described with reference to examples. FIG. 1 is a configuration diagram schematically showing a configuration of an occupant protection device activation device 20 according to one embodiment of the present invention, and FIG. 2 illustrates an arrangement position of the occupant protection device activation device 20 of the embodiment in a vehicle. FIG. The starting device 20 of the occupant protection device of the embodiment is configured as a starting device of an airbag device 50 as an occupant protection device as shown in FIG. 1, and as shown in FIG. A floor sensor 22 disposed on a floor near the front center for detecting acceleration due to impact on the vehicle 10;
The satellite sensor 24 is disposed near the center of the front of the vehicle 0 and detects an acceleration due to an impact on the vehicle 10. The microcomputer 40 includes a CPU 42.

The microcomputer 40 includes a CPU 42
ROM 44 storing a processing program, RAM 46 storing data temporarily, and an input / output processing circuit (I
/ O) 48, the acceleration G1 detected by the satellite sensor 24 and the acceleration G2 detected by the floor sensor 22 are input via the input / output processing circuit 48, and the input / output processing circuit 48 An activation signal can be output to the airbag device 50 via the airbag device 50.

The airbag device 50 includes an airbag 52.
And two inflators 54 for supplying gas to the airbag 52, two ignition devices 56 for igniting a gas generating agent (not shown), and two ignition devices 56 based on a start signal from the microcomputer 40. And two drive circuits 58 for energizing and igniting. Two inflators 5
4 includes a high-speed inflator that simultaneously operates the two inflators 54 to inflate the airbag 52 at a high speed;
This is because the two inflators 54 are operated with a time lag to perform low-speed inflation in which the airbag 52 inflates at a low speed. The selection between the high-speed expansion and the low-speed expansion is set according to the type of collision or the like.

Next, the operation of the starting device 20 of the occupant protection device according to the embodiment configured as described above will be described. FIG.
5 is a flowchart illustrating an example of a startup processing routine executed by the microcomputer 40 of the activation device 20 of the occupant protection device according to the embodiment. In this routine, the acceleration G2 detected by the floor sensor 22 is set to a predetermined value Gre.
f every predetermined time (for example, 100 μsec)
Is executed repeatedly. Note that the predetermined value Gref is
This is an acceleration at which it can be determined that the vehicle 10 has begun to receive an impact, and for example, a value such as 2G or 4G can be used.

When the startup processing routine is executed, the CPU 42 of the microcomputer 40 firstly sets the acceleration G1 detected by the satellite sensor 24 and the floor sensor 2
Then, a process of reading the acceleration G2 detected by Step 2 is executed (Step S100). Subsequently, a short-time integrated value V1 obtained by integrating the acceleration G2 using the read acceleration G2 and integrating the acceleration G2 from the current time to a predetermined time before using the time as an integration section.
0 is calculated (step S102). In the example, the time from the current time to 10 msec before was set as the integration interval, and the short-time integration value V10 was calculated by the following equation (1).

[0022]

(Equation 1)

Next, the read acceleration G1 and acceleration G2
Then, a process of calculating the amount of deformation S of the front portion of the vehicle 10 by the following equation (2) is performed using (step S104).

[0024]

(Equation 2)

Here, the deformation amount S is strictly calculated as the deformation amount of the relative position between the satellite sensor 24 and the floor sensor 22. As shown in FIG. Since the sensor 24 is linearly arranged in front of the vehicle 10 in parallel to the traveling direction, it can be considered as a deformation amount of the front part of the vehicle 10.

It is determined whether or not the short-time integration value V10 for the calculated deformation amount S exceeds the threshold value TH (step S106). When the integration value V10 exceeds the threshold value TH, the driving circuit 58 via the input / output processing circuit 48 Is output (step S108), and this routine ends. The drive circuit 58 to which the start signal has been input energizes and ignites the ignition device 56 to deploy the airbag 52 as described above. If the threshold value TH has not been exceeded, this routine ends without outputting the activation signal.

Step S106 of this startup processing routine
Is set by the threshold setting routine illustrated in FIG. This threshold setting processing routine is executed when the acceleration G2 detected by the floor sensor 22 exceeds a predetermined value Gref, similarly to the activation processing routine. Hereinafter, the setting process of the threshold value TH will be described.

When the threshold setting process routine is executed, the CPU 42 of the microcomputer 40 first executes a process of reading the acceleration G1 detected by the satellite sensor 24 and the acceleration G2 detected by the floor sensor 22 (step). S110). Subsequently, the deformation speed V of the front part of the vehicle 10 is calculated by the following equation (3) using the read acceleration G1 and acceleration G2 (step S).
112).

[0029]

(Equation 3)

Here, the deformation speed V is strictly calculated as a relative speed between the satellite sensor 24 and the floor sensor 22. As shown in FIG. 2, the floor sensor 22 and the satellite sensor 24 Since it is linearly arranged in front of the vehicle 10 in parallel to the traveling direction, it can be considered as the deformation speed of the front part of the vehicle 10.

Next, the calculated deformation speed V is set to a threshold value Vref.
And (Step S114). Here, the threshold Vre
f is set to change the threshold value TH that determines the activation timing of the occupant protection device with respect to the magnitude of the impact acting on the vehicle 10 and the severity of the impact,
It is determined by the shape and characteristics of the vehicle. Deformation speed V is threshold V
If it is less than ref, a pattern of the threshold value TH1 as a default is set as the threshold value TH (step S11).
6) It is determined whether the deformation speed V is not a value 0 over a predetermined period of time (step S118). If the deformation speed V is not a value 0 over a predetermined period of time, it is determined that the deformation is still in progress, and the process proceeds to step S110. The process returns to the processing for reading the acceleration G1 and the acceleration G2. When the deformation speed V has a value of 0 over a predetermined period of time, it is determined that the deformation due to the impact has ended, and this routine ends. Here, the predetermined time is set as a time necessary for determining that the deformation due to the impact has ended.

On the other hand, if the deformation speed V is equal to or higher than the threshold value Vref in step S114, the threshold value TH2 is set to a pattern of the threshold value TH2 corrected below the threshold value TH1 (step S120), and the routine ends.

FIG. 5 is an explanatory diagram for explaining how the threshold value TH is set based on the deformation speed V. In the figure, a curve A indicates a large deformation speed V with respect to the elapsed time.
Shows an example of a time-series change of the deformation speed V when acting on the vehicle 10, and a curve B shows an example of a time-series change of the deformation speed V when an impact indicating a small deformation speed V with respect to the elapsed time acts on the vehicle 10. Show. As shown in the figure, when the impact represented by the curve A acts on the vehicle 10, the deformation speed V exceeds the threshold value Vref at the time t1, and the threshold value TH that determines the activation timing of the occupant protection device at this time is set to the threshold value TH. The pattern of TH2 is set. When the impact represented by the curve B acts on the vehicle 10, the deformation speed V becomes equal to the threshold V
Since the value does not exceed ref, a pattern of a default threshold value TH1 is set as the threshold value TH.

FIG. 6 is an explanatory diagram showing a pattern of the threshold value TH for determining the activation timing of the occupant protection device and the activation timing. In the drawing, a curve C indicates a change in the short-time integral value V10 with respect to the deformation amount S of the front part of the vehicle 10, a pattern TH1 indicates a pattern of the threshold value TH1, and a pattern T
H2 indicates a pattern of the threshold value TH2. As shown in the figure, the pattern of the threshold value TH2 is corrected downward compared to the pattern of the default threshold value TH1, and the airbag device 50 is activated even when the short-time integral value V10 with respect to the deformation amount S is small. That is, when the deformation speed V is high, the threshold value TH
Is corrected downward, so that the activation timing of the airbag device 50 is accelerated to more appropriate activation timing.

According to the occupant protection device activation device 20 of the embodiment described above, the threshold TH for determining the activation timing of the occupant protection device is set based on the deformation speed V of the front portion of the vehicle 10, whereby the occupant protection device is set. The protection device can be activated at a more appropriate timing. Moreover, the vehicle 10
The acceleration G1 and the acceleration G2 detected by the satellite sensor 24 and the floor sensor 22 that are linearly arranged in front of the vehicle and parallel to the traveling direction are used.
Can be calculated more accurately. As a result, the occupant protection device can be activated at a more appropriate timing.

According to the occupant protection device activation device 20 of the embodiment, the activation timing of the occupant protection device can be determined based on the short-time integral value V10 for the deformation amount S of the front portion of the vehicle 10. Deformation amount S of front part of vehicle 10
Is a direct physical quantity, and is suitable for determining the activation timing of the occupant protection device. Therefore, the occupant protection device can be activated at a more appropriate timing. Moreover, since the acceleration G1 and the acceleration G2 detected by the satellite sensor 24 and the floor sensor 22 which are linearly arranged in front of the vehicle 10 in parallel with the traveling direction are used, the deformation amount S is more accurately calculated. be able to. As a result, the occupant protection device can be activated at a more appropriate timing.

In the activating device 20 of the occupant protection device of the embodiment, the accelerations G1 and G2 detected by the satellite sensor 24 and the floor sensor 22 which are linearly arranged in front of the vehicle 10 in parallel with the traveling direction. The deformation speed V is calculated from the following formulas. For example, two speed sensors are linearly arranged in front of the vehicle 10 in parallel to the traveling direction, and the deformation speed V is calculated based on the deviation of the detected value. The deformation speed V may be detected by any method.

Further, the starting device 2 of the occupant protection device of the embodiment.
In the case of 0, two patterns of the threshold value TH1 as the default and a pattern of the threshold value TH2 corrected below the threshold value TH2 are set as the threshold values TH for determining the activation timing. However, three or more threshold value patterns may be set. Alternatively, the threshold value may be set as a function of the deformation speed V.

Furthermore, in the occupant protection device activation device 20 of the embodiment, the activation timing of the occupant protection device is determined based on whether or not the short-time integral value V10 for the deformation amount S of the front portion of the vehicle 10 exceeds the threshold value TH. However, the following equation (4)
The activation timing of the occupant protection device may be determined based on whether or not the short-time integration value V10 with respect to the time integration value Vn calculated by the equation (3) exceeds the threshold value TH. In this case, as the threshold value TH, the same value as that for the deformation amount S may be used, or the value corresponding to the time integration value Vn may be obtained by an experiment or the like and used.

[0040]

(Equation 4)

Alternatively, in the activation device 20 of the occupant protection device of the embodiment, the deformation speed V with respect to the passage of time becomes equal to the threshold value Vr.
threshold T that determines the timing of activation when ef is exceeded
H is changed from the default pattern of the threshold value TH1 to a pattern of the threshold value TH2 corrected below the default value. However, when the change speed V with respect to the variable metric S in the front part of the vehicle 10 exceeds the threshold value, the activation is started. The threshold value TH for determining the timing may be changed, or the above-described equation (4) may be used.
The threshold value TH for determining the start timing may be changed when the change speed V with respect to the time integral value Vn calculated by the above equation exceeds the threshold value.

Further, the starting device 2 for the occupant protection device of the embodiment.
At 0, it is described that the airbag device 50 is activated as an occupant protection device. However, the airbag device 50 may be used as an activation device of another occupant protection device.

The embodiments of the present invention have been described with reference to the embodiments. However, the present invention is not limited to these embodiments, and various embodiments may be made without departing from the scope of the present invention. Of course, it can be carried out.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically illustrating a configuration of an activation device 20 of an occupant protection device according to an embodiment of the present invention.

FIG. 2 is an explanatory view exemplifying an arrangement position of a starting device 20 of the occupant protection device of the embodiment in a vehicle.

FIG. 3 is a flowchart illustrating an example of a startup processing routine executed by the microcomputer 40 of the activation device 20 of the occupant protection device according to the embodiment.

FIG. 4 is a flowchart illustrating an example of a threshold setting processing routine executed by the microcomputer 40 of the activation device 20 of the occupant protection device according to the embodiment.

FIG. 5 is an explanatory diagram illustrating how a threshold value TH is set based on a deformation speed V.

FIG. 6 is an explanatory diagram showing a pattern of a threshold value TH for determining the activation timing of the occupant protection device and the activation timing.

[Explanation of symbols]

Reference Signs List 10 vehicle, 20 occupant protection device activation device, 22 floor sensor, 24 satellite sensor, 40 microcomputer, 42 CPU, 44 ROM, 46 R
AM, 48 input / output processing circuit, 50 airbag device,
52 air bag, 54 inflator, 56 ignition device, 58 drive circuit.

Claims (11)

[Claims] 1. An activation device for an occupant protection device for activating an occupant protection device for protecting an occupant against an impact on a vehicle, wherein the activation device is disposed at a predetermined position of the vehicle and detects acceleration due to the impact. Acceleration detection means, deformation speed detection means for detecting a deformation speed ahead of the vehicle due to the impact, threshold setting means for setting a threshold based on the detected deformation speed, and detection by the first acceleration detection means A starter for activating the occupant protection device based on the set acceleration and a threshold set by the threshold setting device. 2. The activation device for an occupant protection device according to claim 1, wherein the activation device is disposed in front of the vehicle with respect to the first acceleration detecting means.
A second acceleration detecting means for detecting an acceleration due to the impact, wherein the deformation speed detecting means converts the acceleration detected by the first acceleration detecting means into the acceleration detected by the second acceleration detecting means. Calculating a relative speed between a position where the first acceleration detecting means is arranged and a position where the second acceleration detecting means is arranged, based on the calculated relative speed, and detects the calculated relative speed as a deformation speed in front of the vehicle. The starting device of the occupant protection device, which is a means. 3. The activation device for an occupant protection device according to claim 2, wherein the first acceleration detection means is disposed near a front center of an occupant compartment of the vehicle, and the second acceleration detection means is provided. Is disposed in the vicinity of the front center of the vehicle, and the deformation speed detecting means is configured to calculate a deviation of a deviation between the acceleration detected by the first acceleration detecting means and the acceleration detected by the second acceleration detecting means. A starting device for the occupant protection device, which is means for calculating the relative speed by time integration. 4. The occupant protection device activation device according to claim 1, wherein said threshold value setting means sets a smaller threshold value as the detected deformation speed increases. 5. The threshold setting unit includes a plurality of thresholds prepared in advance, and selects and sets a smaller threshold among the plurality of thresholds as the detected deformation speed increases. Item 5. An activating device for an occupant protection device according to Item 4. 6. The starting means integrates a predetermined time from the start of detection of the impact of the acceleration detected by the first acceleration detection means to the present time with respect to a time integral value of the acceleration to the present time. 6. The activation device for an occupant protection device according to claim 1, wherein the activation device activates the occupant protection device when a time integral value of a section reaches the set threshold value. 7. An activation device for an occupant protection device that activates an occupant protection device that protects an occupant against an impact on a vehicle, wherein the activation device is disposed at a predetermined position of the vehicle and detects acceleration due to the impact. Acceleration detection means, deformation amount detection means for detecting an amount of deformation in front of the vehicle due to the impact, based on the detected deformation amount, the acceleration detected by the first acceleration detection means, and a predetermined threshold value A starter for starting the occupant protection device; 8. The activation device for an occupant protection device according to claim 7, wherein the activation device is disposed in front of the vehicle with respect to the first acceleration detection means.
A second acceleration detecting means for detecting an acceleration due to the impact, wherein the deformation amount detecting means detects an acceleration detected by the first acceleration detecting means and an acceleration detected by the second acceleration detecting means. Calculating a relative movement amount between the position where the first acceleration detection means is arranged and the position where the second acceleration detection means is arranged, based on the calculated relative movement amount. The activation device of the occupant protection device, which is a means for detecting the deformation amount of the occupant. 9. The activation device for an occupant protection device according to claim 8, wherein the first acceleration detection means is disposed near a front center of an occupant compartment of the vehicle, and the second acceleration detection means is provided. Is disposed in the vicinity of the front center of the vehicle, and the deformation amount detecting means is configured to calculate a deviation between an acceleration detected by the first acceleration detecting means and an acceleration detected by the second acceleration detecting means. An activation device for an occupant protection device, which is a means for calculating the relative movement amount by second-order time integration. 10. The method according to claim 1, wherein the activation unit is configured to control the first amount of the deformation up to the present time detected by the deformation amount detecting unit.
10. The occupant protection device according to any one of claims 7 to 9, wherein the occupant protection device is activated when a time integration value having a predetermined time up to the present time of the acceleration detected by the acceleration detection means as an integration section reaches the predetermined threshold. A starting device for the occupant protection device according to the above. 11. A starting device for an occupant protection device according to claim 7, wherein a deformation speed detecting means for detecting a deformation speed in front of the vehicle due to the impact, and based on the detected deformation speed. Threshold value setting means for setting a threshold value, wherein the activation means activates the occupant protection device using the threshold value set by the threshold value setting means instead of the predetermined threshold value. apparatus.