阅读说明：本技术 探测装置 (Probe apparatus ) 是由 松本恭平 川上大地 于 2020-12-18 设计创作，主要内容包括：本发明的探测装置具有：滤波器单元,进行对于第1波形进行滤波处理的第1滤波处理和对于第2波形进行滤波处理的第2滤波处理之中的任一者；检测单元,在将所述第1波形的微分波形或所述第2波形设为第3波形的情况下,检测所述第3波形中的规定的峰值即第1峰值的定时；校正单元,基于所述第3波形的所述第1峰值与所述第1峰值之后出现的所述第3波形的第2峰值的差分,校正由所述检测单元检测出的定时即检测值相对所述燃料喷射阀实际地进行所述开阀或所述闭阀的定时的偏移；以及探测单元,基于由所述校正单元校正后的检测值,探测所述燃料喷射阀的所述开阀及所述闭阀中的任一者或两者。(The detection device of the present invention comprises: a filter unit that performs either 1 st filter processing for performing filter processing on a 1 st waveform or 2 nd filter processing for performing filter processing on a 2 nd waveform; a detection unit configured to detect a timing of a 1 st peak, which is a predetermined peak in the 3 rd waveform, when a differential waveform of the 1 st waveform or the 2 nd waveform is a 3 rd waveform; a correction unit that corrects a deviation of a detected value, which is a timing detected by the detection unit, from a timing at which the fuel injection valve actually opens or closes the valve, based on a difference between the 1 st peak of the 3 rd waveform and a 2 nd peak of the 3 rd waveform appearing after the 1 st peak; and a detection unit that detects either one or both of the open valve and the closed valve of the fuel injection valve based on a detection value corrected by the correction unit.)

1. A detection device for detecting either or both of an open valve and a closed valve of a fuel injection valve having a solenoid coil, comprising:

a filter unit that performs either a 1 st filter process for performing a 1 st filter process on a 1 st voltage waveform generated in the solenoid coil or a 2 nd voltage waveform obtained based on the 1 st voltage waveform, or a 2 nd filter process for performing a 2 nd filter process on a 2 nd waveform that is a differential waveform of the 1 st waveform;

a detection unit configured to detect a timing of a 1 st peak, which is a predetermined peak in the 3 rd waveform, when a differential waveform of the 1 st waveform or the 2 nd waveform is a 3 rd waveform;

a correction unit that corrects a deviation of a detection value, which is a timing detected by the detection unit, from a timing at which the fuel injection valve actually opens or closes, based on a difference between the 1 st peak of the 3 rd waveform and a 2 nd peak of the 3 rd waveform appearing after the 1 st peak; and

and a detection unit that detects either one or both of the open valve and the closed valve of the fuel injection valve based on a detection value corrected by the correction unit.

2. The probe apparatus of claim 1,

the correction unit corrects the offset based on a difference between an upward peak of the 3 rd waveform, that is, the 1 st peak, and a downward peak that occurs first after the 1 st peak in the 3 rd waveform, that is, the 2 nd peak.

3. The probe apparatus of claim 2,

the correction means corrects the detection value based on the difference so that the detection value, which is the timing detected by the detection means, coincides with the actual timing at which the fuel injection valve opens or closes.

4. The probe apparatus of claim 1,

the correction means corrects the detection value based on the difference so that the detection value, which is the timing detected by the detection means, coincides with the actual timing at which the fuel injection valve opens or closes.

5. The detection apparatus according to any one of claims 1 to 4,

the filter unit is a finite impulse response filter.

Technical Field

The present invention relates to a probe apparatus.

This application claims priority based on Japanese application No. 2020-.

Background

Japanese patent application laid-open No. 2016-.

Such a control device differentiates a voltage waveform generated by energization to a solenoid coil, and detects a timing of a peak (inflection point) of the differentiated voltage waveform, which is the differentiated voltage waveform, as a timing when a fuel injection valve is closed or opened.

The voltage waveform contains noise. Therefore, the solenoid valve driving device removes noise included in the voltage waveform or the differentiated waveform using a low-pass filter.

Disclosure of Invention

Problems to be solved by the invention

If a low-pass filter is applied to the voltage waveform or the differentiated waveform, dullness of the differentiated waveform occurs. Therefore, for example, the inflection point of the differentiated waveform of the voltage waveform before the noise is removed by the low-pass filter and the inflection point of the differentiated waveform of the voltage waveform after the noise is removed are shifted. Such a deviation of the inflection point is one of the factors that deteriorate the accuracy of detection of the opening or closing of the fuel injection valve.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a detection device that improves the accuracy of detection of an open valve or a closed valve of a fuel injection valve.

Means for solving the problems

(1) One aspect of the present invention is a detection device for detecting either or both of an open valve and a closed valve of a fuel injection valve having a solenoid coil, the detection device including: a filter unit that performs either a 1 st filter process for performing a 1 st filter process on a 1 st voltage waveform generated in the solenoid coil or a 2 nd voltage waveform obtained based on the 1 st voltage waveform, or a 2 nd filter process for performing a 2 nd filter process on a 2 nd waveform that is a differential waveform of the 1 st waveform; a detection unit configured to detect a timing of a 1 st peak, which is a predetermined peak in the 3 rd waveform, when a differential waveform of the 1 st waveform or the 2 nd waveform is a 3 rd waveform; a correction unit that corrects a deviation of a detection value, which is a timing detected by the detection unit, from a timing at which the fuel injection valve actually opens or closes, based on a difference between the 1 st peak of the 3 rd waveform and a 2 nd peak of the 3 rd waveform appearing after the 1 st peak; and a detection unit that detects either one or both of the open valve and the closed valve of the fuel injection valve based on a detection value corrected by the correction unit.

(2) In the detection device according to the above (1), the correction unit may correct the offset based on a difference between the 1 st peak, which is an upward peak of the 3 rd waveform, and the 2 nd peak, which is a downward peak appearing first after the 1 st peak in the 3 rd waveform.

(3) In the detection device according to the above (1) or (2), the correction unit may correct the detection value based on the difference so that a detection value that is a timing detected by the detection unit coincides with a timing at which the actual fuel injection valve is opened or closed.

(4) In the detection apparatus according to any one of the above (1) to (3), the filter unit may be a finite impulse response filter.

Effects of the invention

As described above, according to the above aspect of the present invention, the accuracy of detecting the opening or closing of the fuel injection valve can be improved.

Drawings

Fig. 1 is a diagram showing a configuration example of a fuel injection valve L according to an embodiment of the present invention.

Fig. 2 is a diagram showing a configuration example of the solenoid valve driving device 1 according to the same embodiment.

Fig. 3 is a diagram illustrating a method of correcting the offset Δ Toffset according to the same embodiment.

Fig. 4A is a diagram illustrating a method of generating the 3 rd waveform according to the same embodiment.

Fig. 4B is a diagram illustrating a method of generating the 3 rd waveform according to the same embodiment.

Description of the reference symbols

1 solenoid valve drive device

4 solenoid coil

300 control device (detecting device)

340 filter unit

350 differential operation unit

360 detection unit

370 correction unit

380 detection unit

L fuel injection valve

Detailed Description

Hereinafter, a solenoid valve driving device according to an embodiment of the present invention will be described with reference to the drawings.

As shown in fig. 1, an electromagnetic valve driving device 1 of the present embodiment is a driving device for driving a fuel injection valve L. Specifically, the electromagnetic valve drive device 1 of the present embodiment is an electromagnetic valve drive device that drives a fuel injection valve L (electromagnetic valve) that injects fuel into an internal combustion engine mounted in a vehicle.

The fuel injection valve L is an electromagnetic valve (solenoid valve) that injects fuel into an internal combustion engine, such as a gasoline engine or a diesel engine, mounted on a vehicle.

Hereinafter, a configuration example of the fuel injection valve L will be described with reference to fig. 1.

As shown in fig. 1, the fuel injection valve L has a fixed core 2, a valve seat 3, a solenoid coil 4, a needle (needle)5, a valve body 6, a retainer (retainer)7, a lower stopper (lower stopper)8, a valve body urging spring 9, a movable core 10, and a movable core urging spring 11. In the present embodiment, the fixed core 2, the valve seat 3, and the solenoid coil 4 are fixed members, and the needle 5, the valve element 6, the retainer 7, the lower stopper 8, the valve element biasing spring 9, the movable core 10, and the movable core biasing spring 11 are movable members.

The fixed core 2 is a cylindrical member and is fixed to a housing (not shown) of the fuel injection valve L.

The fixed core 2 is formed of a magnetic material.

The valve seat 3 is fixed to a housing of the fuel injection valve L. The valve seat 3 has an injection hole 3 a.

The injection hole 3a is a hole for injecting fuel, and is closed when the valve element 6 is seated on the valve seat 3, and is opened when the valve element 6 is separated from the valve seat.

The solenoid coil 4 is formed by winding a wire in a ring shape. The solenoid coil 4 is arranged concentrically with the stationary core 2.

The solenoid coil 4 is electrically connected to the solenoid valve driving device 1. The solenoid coil 4 is energized by the solenoid valve driving device 1 to form a magnetic circuit including the fixed core 2 and the movable core 10.

The needle 5 is an elongated rod member extending along the central axis of the stationary core 2. The needle 5 moves in the axial direction of the center axis of the fixed core 2 (the extending direction of the needle 5) by the attractive force generated by the magnetic circuit including the fixed core 2 and the movable core 10. In the following description, in the axial direction of the central axis of the fixed core 2, the direction in which the movable core 10 moves by the above-described suction force is referred to as an upward direction, and the direction opposite to the direction in which the movable core 10 moves by the above-described suction force is referred to as a downward direction.

A valve body 6 is formed in the lower front end of the needle 5. The valve body 6 closes the injection hole 3a by being seated on the valve seat 3, and opens the injection hole 3a by being separated from the valve seat 3.

The holder 7 has a guide member 71 and a flange 72.

The guide member 71 is a cylindrical member fixed to the upper end of the needle 5.

A flange 72 is formed to project in the radial direction of the needle 5 in the upper end of the guide member 71.

The end surface below the flange 72 is a contact surface with the movable core biasing spring 11. The upper end surface of the flange 72 is a contact surface with the valve element biasing spring 9.

The lower stopper 8 is a cylindrical member fixed to the needle 5 between the valve seat 3 and the guide member 71. The upper end surface of the lower retainer 8 is a contact surface with the movable core 10.

The valve body urging spring 9 is a compression coil spring accommodated inside the fixed core 2, and is sandwiched between the inner wall surface of the housing and the flange 72. The valve body biasing spring 9 biases the valve body 6 downward. That is, when the solenoid coil 4 is not energized, the valve element 6 is abutted against the valve seat 3 by the biasing force of the valve element biasing spring 9.

The movable core 10 is disposed between the guide member 71 and the lower stopper 8. The movable core 10 is a cylindrical member and is provided coaxially with the needle 5. The movable core 10 is formed with a through hole in the center thereof through which the needle 5 passes, and is movable in the extending direction of the needle 5.

The upper end surface of the movable core 10 is a contact surface with the fixed core 2 and the movable core biasing spring 11. On the other hand, the lower end surface of the movable core 10 is a contact surface with the lower stopper 8. The movable core 10 is formed of a magnetic material.

The movable core urging spring 11 is a compression coil spring interposed between the flange 72 and the movable core 10. The movable core biasing spring 11 biases the movable core 10 downward. That is, when the solenoid coil 4 is not energized, the movable core 10 is abutted against the lower stopper 8 by the urging force of the movable core urging spring 11.

Next, the solenoid valve driving device 1 of the present embodiment will be described.

As shown in fig. 2, the solenoid valve driving device 1 includes a driving device 200 and a control device 300.

The driving device 200 includes a power supply device 210 and a switch 220.

The power supply device 210 has at least one of a battery and a booster circuit. The battery is loaded in a vehicle. The booster circuit boosts a battery voltage Vb that is an output voltage of the battery, and outputs a boosted voltage Vs that is the boosted voltage. The power supply device 210 may output the battery voltage Vb to the solenoid coil 4.

The power supply device 210 energizes the solenoid coil 4 by outputting the boosted voltage Vs to the solenoid coil 4. The power supply device 210 may energize the solenoid coil 4 by outputting the battery voltage Vb to the solenoid coil 4. The voltage output from the power supply device 210 to the solenoid coil 4 is controlled by the control device 300. Further, the energization of the solenoid coil 4 is controlled by the control device 300.

The switch 220 is controlled in its on state or off state by the control device 300. When the switch 220 is controlled to be in the on state, the voltage output from the power supply device 210 is supplied to the solenoid coil 4. This starts energization of the solenoid coil 4. When the switch 220 is controlled to be in the off state, the supply of the voltage from the power supply device 210 to the solenoid coil 4 is stopped.

The control device 300 includes a voltage detection unit 310, a control unit 320, and a storage unit 400. The control device 300 is an example of the "detection device" of the present invention.

The voltage detection unit 310 detects the voltage Vc generated in the solenoid coil 4. For example, the voltage Vc is a voltage across the solenoid coil 4. Voltage detection section 310 outputs detected voltage Vc to control section 320.

The control unit 320 has a energization control unit 330, a filter unit 340, a differential operation unit 350, a detection unit 360, a correction unit 370, and a detection unit 380.

The energization control unit 330 controls the power supply device 210. The energization control unit 330 controls the switch 220 to be in an on state or an off state. The energization control unit 330 controls the switch 220 to be in an on state, thereby supplying the voltage from the power supply device 210 to the solenoid coil 4. The energization control unit 330 controls the switch 220 from the on state to the off state, thereby stopping the supply of the voltage from the power supply device 210 to the solenoid coil 4. When the supply of the voltage to the solenoid coil 4 is stopped, a counter electromotive force is generated in the solenoid L, and a reverse voltage is generated across both ends of the solenoid L. The reverse voltage decreases with time and disappears after a certain time. Before such a voltage difference disappears, the valve element 6 of the opened fuel injection valve L collides with the valve seat 3 and is closed, and the decrease gradient of the voltage difference changes when the valve element 6 collides with the valve seat 3. The control unit 320 of the present embodiment detects the closing of the fuel injection valve L by detecting the change in the decrease gradient.

Filter section 340 generates filtered waveform Wf by performing filtering processing on waveform (hereinafter, referred to as "voltage waveform") Wv of voltage Vc output from voltage detection section 310. This voltage Vc is a voltage Vc obtained by controlling the switch 220 from the on state to the off state. The filtering process is a process of removing a noise component included in the voltage waveform Wv of the voltage Vc. For example, the filter unit 340 is a low pass filter. The filter unit 340 is, for example, a Finite Impulse Response (FIR) filter. Filter section 340 outputs the generated filtered waveform Wf to differential operation section 350. The voltage waveform Wv is an example of the "1 st waveform" of the present invention.

The differentiation operation unit 350 generates a differentiated waveform Wd by time-differentiating the filtered waveform Wf generated in the filter unit 340. The differential operation unit 350 outputs the generated differential waveform Wd to the correction unit 370. The differential waveform Wd in the present embodiment is the first order differential of the voltage waveform Wv, but is not limited to the first order differential, and may be a higher order differential of a second order differential or more. The differential waveform Wd is an example of the "waveform 3" of the present invention.

The detection unit 360 includes a 1 st detection unit 361 and a 2 nd detection unit 362.

The 1 st detecting unit 361 detects a 1 st peak, which is a predetermined peak of the differential waveform Wd, and a timing Tp of the 1 st peak. In the present embodiment, the 1 st peak is a differential value of an upward peak in the differential waveform Wd. For example, the detection unit 360 detects a differential value of an upward peak (hereinafter, referred to as "1 st peak") P1 appearing first in the differential waveform Wd as a 1 st peak. For example, timing Tp of the 1 st peak is a time when the 1 st peak is detected by 1 st detecting section 361. For example, the 1 st detecting unit 361 detects the time from when the energization of the solenoid coil 4 is stopped to the 1 st peak as the timing Tp.

The 2 nd detection unit 362 detects a 2 nd peak value occurring after the 1 st peak value in the differential waveform Wd. In the present embodiment, the 2 nd peak is a differential value of a peak downward in the differential waveform Wd. For example, the detection unit 360 detects a differential value of a downward peak appearing first after the 1 st peak in the differential waveform Wd as the 2 nd peak.

The correcting unit 370 corrects the deviation Δ Toffset from the timing at which the actual fuel injection valve L is closed in the detection value (timing Tp) of the 1 st detecting unit 361 based on the difference Δ Y between the 1 st peak value of the differential waveform Wd and the 2 nd peak value of the differential waveform Wd that appears after the 1 st peak value. For example, the correction unit 370 corrects the offset Δ Toffset based on the difference Δ Y between the 1 st peak and the 2 nd peak detected by the detection unit 360.

For example, correction section 370 calculates the difference Δ Y between the 1 st peak detected by 1 st detection section 361 and the 2 nd peak detected by 2 nd detection section 362. The correction unit 370 corrects the detection value (timing Tp) of the 1 st detection unit 361 based on the difference Δ Y so that there is no offset Δ Toffset. For example, the correction unit 370 reads the offset Δ Toffset corresponding to the difference Δ Y from the information X stored in the storage unit 400. Then, the correction unit 370 corrects the detection value of the 1 st detection unit 361 by adding the read offset Δ Toffset thereto. The correction unit 370 outputs the corrected detection value (hereinafter, referred to as "correction value") to the detection unit 380. This makes the correction value equal to the timing at which the actual fuel injection valve L is closed.

The detection unit 380 detects the closing of the fuel injection valve L based on the correction value. In the present embodiment, the detection means 380 detects that the fuel injection valve L is closed during the time indicated by the correction value.

The information X is stored in the storage unit 400. The information X is information with which the difference Δ Y and the offset Δ Toffset are associated. The present inventors have obtained the finding that there is a correlation between the difference Δ Y and the offset Δ Toffset. As the difference Δ Y increases, the offset Δ Toffset similarly increases. On the other hand, when the difference Δ Y decreases, the offset Δ Toffset also decreases similarly. For example, the offset Δ Toffset is expressed as a function of the difference Δ Y as a variable.

The difference Δ Y between the 1 st peak and the 2 nd peak of the differential waveform Wd varies depending on the characteristics of the filtering process. The timing at which the fuel injection valve L is actually closed is when an upward peak of the differential waveform Wx of the voltage waveform Wv that is not subjected to the filtering process occurs. Also, the temporal offset Δ Toffset occurring between the upward peak of the differential waveform Wx and the upward peak (1 st peak) of the differential waveform Wd also varies depending on the characteristics of the filtering process. That is, the difference Δ Y and the offset Δ Toffset represent the same characteristic of the filtering process, and have a correlation.

The information X is information of an equation and a table, etc., to which the difference Δ Y and the offset Δ Toffset are associated.

The operation and effect of the present embodiment will be described below.

The control unit 320 starts energization to the solenoid coil 4 at a predetermined energization start time. Then, control section 320 stops the energization of solenoid coil 4 during an energization stop time that is a time after a predetermined time has elapsed from the energization start time. When the energization of the solenoid coil 4 is stopped, a reverse voltage is generated across the solenoid coil 4. The reverse voltage decreases with time and disappears after a certain time. Before such a voltage difference disappears, the valve element 6 of the fuel injection valve L collides with the valve seat 3, and the fuel injection valve L is closed. When the fuel injection valve L is closed, the inductance in the magnetic circuit formed in the fuel injection valve L changes. The voltage difference, i.e., the voltage Vc, varies due to the variation of the inductance.

Therefore, the control unit 320 can detect the closing of the fuel injection valve L by detecting the inflection point of the differentiated waveform Wx that is a waveform obtained by differentiating the voltage waveform Wv of the voltage Vc. However, the differential waveform Wx contains noise of a high-frequency component. Therefore, the control unit 320 removes the noise of the high frequency component included in the voltage waveform Wv by applying a low-pass filter such as an FIR filter to the voltage waveform Wv. Then, control section 320 generates a noise-removed differential waveform Wd by differentiating the voltage waveform (filtered waveform Wf) from which the noise of the high-frequency component is removed.

However, as shown in fig. 3, the inflection point f2(P1) of the differential waveform Wd is temporally offset by Δ Toffset from the inflection point f1 of the differential waveform Wx. Here, the timing Tx at which the inflection point of the differential waveform Wx appears is the timing at which the fuel injection valve L closes. Therefore, when the timing Tp at which the inflection point of the differential waveform Wd appears is detected as the valve closing timing of the fuel injection valve L, the detected value includes a deviation Δ Toffset from the actual timing at which the fuel injection valve L is closed.

Therefore, the control unit 320 corrects the offset Δ Toffset included in the detection value based on the difference Δ Y, using the correlation between the difference between the 1 st peak and the 2 nd peak of the differential waveform Wd, that is, the difference Δ Y and the offset Δ Toffset. Specifically, the control unit 320 detects the inflection point of the differential waveform Wd, and corrects the detection value (timing Tp) based on the difference Δ Y so that there is no shift Δ Toffset. Thereby, the control unit 320 can improve the detection accuracy of the closed valve of the fuel injection valve L.

While one embodiment of the present invention has been described above with reference to the drawings, the specific configuration is not limited to this embodiment, and design and the like without departing from the scope of the present invention are also included.

The filter unit 340 generates a filter waveform Wf by performing filter processing on the voltage waveform Wv (1 st voltage waveform). However, the filter unit 340 may generate the filter waveform Wf by performing filter processing not on the voltage waveform Wv detected by the voltage detection unit 310 but on a voltage waveform (2 nd voltage waveform) obtained based on the voltage waveform Wv. The voltage waveform obtained based on the voltage waveform Wv may be a voltage waveform obtained by applying a predetermined process to the voltage waveform Wv, instead of the voltage waveform Wv itself detected by the voltage detection unit 310. The prescribed treatment is not particularly limited. For example, the voltage waveform obtained based on the voltage waveform Wv may be a difference waveform which is a difference between a normal operation waveform which is a voltage waveform of the fuel injection valve when the fuel injection valve is operated and a non-operation waveform which is a voltage waveform of the fuel injection valve when the fuel injection valve is not operated, which is described in japanese patent laid-open No. 2016-180345.

The detection unit 380 of the above embodiment detects the closing of the fuel injection valve L based on the correction value. However, the detection means 380 is not limited to this, and may detect the opening of the fuel injection valve L based on the correction value. In this case, the offset Δ Toffset represents an offset between the timing of the inflection point detected by the 1 st detecting means 361 and the actual timing at which the fuel injection valve L opens. That is, the correcting unit 370 corrects the timing detected by the 1 st detecting unit 361, that is, the deviation Δ Toffset from the actual timing at which the fuel injection valve L opens, in the detected value, based on the difference Δ Y between the 1 st peak value of the differential waveform Wd and the 2 nd peak value of the differential waveform Wd that appears after the 1 st peak value.

As shown in fig. 4A, the differentiation operation means 350 of the above embodiment differentiates the filter waveform Wf, which is the voltage waveform filtered by the filter means 340, but is not limited thereto, and may differentiate the voltage waveform input to the filter means 340 as shown in fig. 4B. That is, the differentiation unit 350 may differentiate one of the 1 st voltage waveform and the 2 nd voltage waveform (the 1 st waveform) (fig. 4B). In this case, filter section 340 performs filtering processing on the differential waveform (2 nd waveform) of the 1 st voltage waveform or the 2 nd voltage waveform, and outputs the differential waveform after the filtering processing to correction section 370 (fig. 4B). Therefore, filter section 340 performs any one of the 1 st filter process (fig. 4A) of performing the filter process on the 1 st waveform that is any one of the 1 st and 2 nd voltage waveforms, and the 2 nd filter process (fig. 4B) of performing the filter process on the 2 nd waveform that is a differential waveform of the 1 st waveform.

Detection section 360 detects the timing of a 1 st peak, which is a predetermined peak of a 3 rd waveform that is either a differential waveform of the 1 st waveform subjected to the 1 st filtering process or a 2 nd waveform subjected to the 2 nd filtering process. The correcting unit 370 corrects the timing detected by the detecting unit, that is, the deviation from the timing at which the actual fuel injection valve opens or closes in the detected value based on the difference between the 1 st peak of the 3 rd waveform and the 2 nd peak of the 3 rd waveform appearing after the 1 st peak.

Control section 320 of the present embodiment delays or advances the detection value, which is the timing detected by 1 st detecting section 361, by a time (offset Δ Toffset) corresponding to difference Δ Y. Thereby, control section 320 detects the detected value as the valve-opening timing or the valve-closing timing by the time delayed or advanced by the offset Δ Toffset. Therefore, the control unit 320 can improve the detection accuracy of at least one of the closed valve and the opened valve of the fuel injection valve L.

The filter unit 340 may also be an FIR filter. The FIR filter has a characteristic that phase distortion does not easily occur. Therefore, the control unit 320 can further improve the detection accuracy of at least one of the closed valve and the opened valve of the fuel injection valve L by using an FIR filter as the filter unit 340.

Further, all or a part of the control unit 320 may be implemented by a computer. In this case, the computer may include a processor such as a CPU or a GPU, and a computer-readable recording medium. Further, the program for realizing all or a part of the functions of the control unit 320 by a computer may be recorded in the computer-readable recording medium, and the program recorded in the recording medium may be read and executed by the processor. Here, the "computer-readable recording medium" refers to a storage device such as a flexible disk, a magneto-optical disk, a removable medium such as a ROM or a CD-ROM, or a hard disk incorporated in a computer system. The "computer-readable recording medium" may include a recording medium that dynamically holds a program for a short period of time, such as a communication line in the case where the program is transmitted via a network such as the internet or a communication line such as a telephone line, or a recording medium that holds a program for a certain period of time, such as a volatile memory inside a computer system serving as a server or a client in this case. The program may be a program for realizing a part of the above-described functions, a program for realizing the above-described functions by combining with a program already recorded in a computer system, or a program realized by using a programmable logic device such as an FPGA.