JPS63164517A - High pass filter device - Google Patents

Abstract

PURPOSE:To remove a DC component or the like superposed to an acceleration signal within a short time by changing the time constants of high pass filters (HPFs) in accordance with a previously fixed time sequence. CONSTITUTION:A HPF device consists of HPFs 25a, 25b including switching mechanisms to be time constant changing means, analog switches 21a, 21b constituting switching means for switching the time constants of respective HPFs 25a, 25b, delay circuits 23a, 23b to be switching drive control means for controlling the operation of the analog switches 21a, 21b, OR circuits 24a, 24b, and an adder 25c for adding the outputs of the HPFs 25a, 25b. The time constants of the HPFs 25a, 25b are changed in accordance with the time sequence previously fixed by the delay circuits 23a, 23b.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a high-pass filter used in a vibration detection device for equipment that receives relatively low-frequency vibrations, and more particularly, to a high-pass filter that is used in a vibration detection device for equipment that receives relatively low-frequency vibrations, and more particularly, for high-pass filters that are installed in equipment such as cameras. It is related to a high-pass filter that is suitably used in a system that detects vibrations (camera shake acceleration) with a frequency of about IHz to 12Hz and uses this as information for preventing image blur, and in particular, it is used to prevent image blur from being superimposed on a signal. The present invention relates to a high-pass filter device that is used to output true manual acceleration information from which direct current components have been removed in the shortest possible time.

(Background of the Invention) The conventional technology to which the present invention is applied will be explained below using a camera as an example.

In modern cameras, all important tasks for photography, such as exposure determination and focusing, are automated, so even people who are inexperienced in camera operation are less likely to make a shooting mistake, or the only problem is a shooting mistake due to camera shake. cannot be automatically prevented.

Therefore, research has recently been conducted on cameras that can prevent shooting failures caused by camera shake, and in particular, research and development are progressing on cameras that can prevent shooting failures caused by the photographer's manual movements. It is being

The above camera shake usually has a frequency of IHz to 121
(In terms of z-vibration, in order to be able to take pictures without image blur even if such camera shake occurs at the time of camera shutter release, it is necessary to detect the camera vibration caused by the camera shake, In accordance with the detected value, the correction lens must be displaced in accordance with the direction of the vibrational displacement of the camera.Therefore, the above purpose (i.e., to be able to take photographs that do not cause image blur even when camera shake occurs) ), it is necessary to accurately detect camera vibrations (especially vibrations caused by camera shake).

In principle, camera shake detection is achieved by using a camera shake detection system that includes an accelerometer that outputs an acceleration signal and an integrator that performs first-order integration or second-order integration of the acceleration signal and outputs a velocity signal or displacement signal. This can be done by installing it on.

Here, an outline of the camera pre-detection system using an accelerometer will be explained using FIG. 3.

The example in FIG. 3 is a diagram of a system for detecting vertical camera shake in the four directions shown by the arrows, and the horizontal camera shake detection system in the direction perpendicular to the page is omitted. In the figure, 1 is the camera body, 2 is the lens barrel, 3a1, 3b
1 is two accelerometers each capable of detecting minute acceleration such as a servo accelerometer, and the acceleration detection direction of each is 3a2
, 3b2. A similar accelerometer may be used to detect horizontal camera shake, but in this case, the direction of acceleration detection is 90 degrees to the arrows 3a2 and 3J, that is, perpendicular to the plane of the paper.

5 is a differential amplifier that calculates the difference between the outputs of the two accelerometers 3a1 and 3b1, and 7 is a known analog integration circuit (hereinafter simply referred to as an integration circuit), which performs first-order integration of the differential acceleration signal from the differential amplifier. Convert to manual velocity or manual displacement by second-order integration.

The operation of the above camera pre-detection system will be explained.

Suppose now that a photographer holds a camera and starts aiming at a subject.

At this time, the camera slightly shakes in the direction of arrow 4 and in the direction perpendicular to the page. This vibration has a frequency of 111z to 12Hz
It is the vibration of

When the camera shakes in the four directions of the arrows, the accelerometer 3a1,
Different shaking accelerations are manually applied to 3b1. This is because, for example, when the camera moves around point 0 shown in FIG. 3, the acceleration is applied to the accelerometer 3a1 that is farther away from point O than to the accelerometer 3b1 that is closer to point 0. It is. These two accelerometers 3a1 and 3b
By calculating the difference between the two outputs using a differential amplifier, an acceleration signal generated when the camera shakes in the four directions of the arrows (vertical vibration) can be obtained.

This signal is integrated by the integrator 7 to convert it into the camera hand movement velocity or hand movement displacement, but due to variations in accuracy of the accelerometers 3a1 and 3b1 and the influence of gravitational acceleration, the differential acceleration signal requires direct current. The components are superimposed, and if you integrate this signal as it is, the DC component will also be integrated, so the obtained hand-pulling speed or hand-pulling displacement will be completely different from the actual hand-pulling speed and one hand-pulling displacement. Put it away.

Furthermore, as shown in FIG. 5, the outputs of the accelerometers 3a1 and 3b1 include extremely low frequency components due to noise etc. together with the hand motion acceleration signal 13, which is also a factor that deteriorates the accuracy of the camera motion detection system. becomes.

Therefore, it has been considered to connect a high-pass filter 6 between the differential amplifier 5 and the integrator 7, but when a known high-pass filter is used for this, there are problems described below. Note that the following explanation assumes that a sine wave signal to which a DC component is added is used as the manual acceleration signal, but this means that the manual acceleration signal has a frequency of 1 to 12 [Hz].
] It is created by superimposing sine waves with various amplitudes and various phase angles at the frequency of It is.

Now, one of the typical configurations of the above-mentioned high-pass filter 6 is as follows.
As shown in FIG. 4(a), resistors 1111. It is a series circuit of a capacitor 1121, and when the differential acceleration signal from the differential amplifier 5 is input from the terminal 91, the terminal 10
1, a signal with DC components and extremely low frequency noise removed is obtained.

Alternatively, as shown in FIG. 4(b), a high-pass filter is configured by an operational amplifier 214, a resistor 2111, and a capacitor 2121;
It is also conceivable to use a circuit that cuts high frequencies at 122. In this case, a differential acceleration signal is input from the terminal 92, and a signal from which the DC component, extremely low frequency noise, and high frequency noise have been removed is output from the terminal 102.

FIG. 6 is a diagram for explaining the DC component removal ability when using the high-pass filter shown in FIG. ° indicates the signal zero point, and 2171 indicates the DC component. Further, 2151 indicates a signal output from the terminal 102 after passing through a high-pass filter, and 215+
o indicates the signal zero point.

As can be seen from FIG. 6, the DC component of the signal 2151 after passing through the high-pass filter has been removed up to the point of arrow 2181 in the figure, and the time τ1 until the DC component is removed is ``initial wait''. This initial waiting time is given as follows.

That is, as already mentioned, camera shake vibrations occur at a rate of about 1 to 12 times per second (that is, the vibration frequency is around 1 to 12 Hz), and therefore, as shown in Figure 4 (a) above, (b) Resistor 111. ,
2111, capacitor 1121゜2121 is set to a predetermined value that does not impair the accuracy of the manual acceleration signal from which DC and extremely low frequency signals have been removed after passing through the high-pass filter, and is given depending on such settings. The length of the above-mentioned "initial waiting time" is derived from the time constant of the high-pass filter, but in reality, the values of the resistance and capacitor of the high-pass filter of the above configuration are determined as appropriate for high-precision detection. For example, in the example of FIG. 4(b), if the resistor 2111 is 2.2 [MΩ] and the capacitor 2121 is 1 [μF], then the "initial waiting time" is The time '' takes a value of nearly 10 seconds (approximately the same value is obtained in FIG. 4(a)).

If the hand vibration frequency exists in the vicinity of 0.5 to 12 Hz, and it is attempted to remove DC and extremely low frequency components without impairing accuracy, a longer waiting time will be required;
It goes without saying that the waiting time can be shortened if it exists at ~12 Hz.

However, such an "initial waiting time" of 10 seconds means that it is necessary to wait for a long time while holding the camera, so it should be said that it is not preferable for actual photography.

Therefore, a high-pass filter having the configuration shown in FIG. 7 can be considered to compensate for such problems.

The high-pass filter having the configuration shown in FIG. 7 is provided so that the connection of a resistor 3111 that determines a time constant can be switched to a parallel composite resistance state with a resistor 3113 by operating a switch S1. In other words, in the high-pass filter having the configuration shown in FIG. 7, initially the switch S1 is turned on and the time constant determining resistance is made into a parallel composite resistance of the resistor 311 and the resistor 3113 to reduce the resistance value, thereby reducing the time constant ( For example, the time constant T1) is also made small to quickly remove the DC component, and then the switch S1 is turned off to obtain a highly accurate manual acceleration output corresponding to the AC input. The circuit is configured to return to T2>T1). Note that in the circuit of FIG. 7, the resistor 311. Also, the resistor 3112 and the resistor 3114 are turned on and off by turning on and off the switch S2.
The return to the normal state when the switch S2 is off is performed from the state of the parallel combined resistance with It is something. Therefore, the switch s1. S2 is provided to switch synchronously.

FIGS. 8(a) and 8(b) are diagrams showing the waveforms of signals obtained by the operation of the high-pass filter configured as shown in FIG. 7, and as shown in FIG. The manual acceleration signal input to the terminal 93 in the figure is shown at 316.
2, the arrow 3192 in FIG. 8(a)
At the time of switching the time constant shown by (when switches s, , S2 are off), the manual acceleration becomes the minimum (when the acceleration is the minimum), and the output after passing through the high-pass filter is as shown in 3152, as described above. The time τ2, which is the "initial waiting time", becomes very short. but,
The input manual acceleration signal and the time constant switching point are not always obtained in such an ideal manner; for example, as shown in FIG. 8(b), the input manual acceleration signal and the time constant switching point are Assuming that the hand acceleration signal is as shown in the figure 3163, the hand acceleration is at its maximum (when the acceleration is if the maximum)
The output after passing through the high-pass filter is 315 as shown in the figure.
3, and 2 becomes a long time due to the above-mentioned "initial waiting time".

In reality, the time constant switching point is shown in FIG. 8 (a).
) and Figure 8(b), and the ideal state shown in Figure 8(a) can always be maintained by the configuration shown in Figure 7. It is difficult to secure it. Therefore, the high-pass filter having the configuration shown in FIG. 7 is considerably improved in terms of stabilizing the output in the shortest possible time compared to the high-pass filter of the example shown in FIG. 4 above. ,
Further improvements need to be considered for applications that require output stability in a shorter time.

Further, when the high-pass filter having the configuration shown in FIG. 7 was carefully examined, it was found that there were further points to be improved as described below.

In other words, if we take the camera shake problem as an example and consider the relationship between the time constant of the high-pass filter and the camera shake frequency,
If the time constant set in the high-pass filter is T, then signals with frequencies equal to or less than the equation (1) are attenuated by the high-pass filter.

Furthermore, since camera shake generally exists in the range of 1 to 12 [Hz], let us assume that the frequency in equation (1) above is 1 to 12 [Hz].
If it is set to between 2 Hz or more, even the camera's manual signal will be attenuated by the high-pass filter, and the detection accuracy of the acceleration signal to be detected will be significantly deteriorated. Therefore, in order to accurately detect the acceleration signal, the frequency value of the above equation (1) should basically be 1 [1
(z] or less, but if we consider not only this, but also factors that degrade output accuracy such as phase shifts near the frequency value of equation (1), the equation (1) must be set to It is desirable to set the frequency value to a value sufficiently smaller than 1 [Hz], for example, about 0.07 [1(z]) or less.This allows the above-mentioned time constant T
(T2 in the example of FIG. 7) is determined.

On the other hand, as already mentioned, in order to quickly stabilize the output of the high-pass filter, it is desirable that the time constant (time constant T1 when each S, S2 is off) is sufficiently small.

The above means that in order to quickly stabilize the output of the high-pass filter, the time constant T given by switching the switch in the configuration shown in FIG. For example, to be extreme, it is preferable to set the time constant such that the value of the above equation (1) is 10 [Hz], but on the other hand, after stabilization (
In order to obtain high output accuracy of the high-pass filter device (after switching to T2), it is desirable that the value of the above equation (1) be approximately < 0.07 [H2] or less as described above.

However, if this is done, the time constants T1 and T2 that satisfy both requirements will have values that are quite different from each other, and as a result, the phase of the output waveform from the high-pass filter will change immediately before and after the time constant switching.

The magnitudes of the outputs will be too different, causing discontinuity in the output at the time of switching, which tends to cause the problem that the precision of the output waveform deteriorates as shown in FIG. 8(b). It is difficult to set T2 to a value with a large difference. Therefore, it cannot be said that the initial waiting time is significantly improved compared to the example shown in FIG. 4(b).

(Object of the Invention) The present invention has been made in consideration of the various problems described above, and its purpose is to detect high-pass It is an object of the present invention to provide a high-pass filter device that is capable of removing DC components and the like superimposed on an acceleration signal in the shortest possible time, and that is suitably used for highly accurate signal detection.

Another object of the present invention is to provide a high-pass filter device that can be suitably used particularly in a camera pre-detection system and furthermore in an image pre-prevention system.

(Summary of the Invention) The feature of the high-pass filter device according to the present invention, which has been made to achieve the above object, is that it is a high-pass filter device that removes DC components and/or low frequency components from an AC input, and includes: a plurality of high-pass filters whose time constants are changeable from a state with a small time constant set as an initial state to a state with a large time constant thereafter, and which are connected in parallel to the AC input; After the high-pass filter starts operating, these time constants are independently reduced.
a time constant changing means for changing the time constant of the plurality of high-pass filters by the time constant changing means according to a predetermined time series;
The configuration includes an adder circuit that adds the outputs of the plurality of high-pass filters.

Changing the time constant in the above configuration includes various switching methods, such as an analog switch method that instantly switches between two set values, and a smooth switch method that uses a variable resistor.

In addition, the small time constant of the high-pass filter is set to a predetermined value corresponding to the degree of broadening of the frequency range of the AC input (for example, the hand motion acceleration signal of the camera) that is to be detected by the device of the present invention, as described above. do it.

Furthermore, the time-series setting of the timing of changing the time constants of the plurality of high-pass filters, which is performed by the switch drive control means, for example, via the switch means, depends on the frequency and configuration of the AC input to be detected by the device of the present invention. It can be determined theoretically or experimentally depending on the number of high-pass filters to be used, but for example, if the detection target is hand vibration of the camera and there are two high-pass filters. Generally, the time interval is preferably about 0.5 seconds.

Furthermore, the high-pass filter device having the above configuration simply adds and outputs the outputs of a plurality of high-pass filters, and corrects the magnitude of the overall output by an appropriate circuit connected as necessary to the subsequent stage of the device. Alternatively, the adder circuit may be provided in a format that adds the outputs of each high-pass filter and performs division by the number of high-pass filters.

In the above configuration, it goes without saying that the time constant of the high-pass filter whose time constant is changed later must be changed at least before the output of the high-pass filter whose time constant has been changed first is stabilized.

(Embodiments of the Invention) The present invention will be described below with reference to the drawings, taking as an example a case where the present invention is applied to an image blur prevention system for a camera.

FIG. 1 shows an outline of the configuration of a high-pass filter device according to the present invention as a block circuit, and in the figure, reference numeral 94 is an input that receives, for example, the acceleration difference from the accelerometers 3a1 and 3b1 shown in FIG. Shows terminals.

Further, 104 indicates an output terminal of the high-pass filter device.

The configuration overview of the high-pass filter device of this example includes a plurality of high-pass filters (in this example, two, 25a and 25b) incorporating a switching mechanism serving as a time constant changing means, and a time constant switching mechanism for each of these high-pass filters. A plurality of analog switches (in this example, 21
a.

21b), a plurality of delay circuits (in this example, 23a and 23b) and an OR circuit (in this example, 24a and 24b) as switch drive control means for controlling the operation of these multiple analog switches; The adder circuit 25c adds the outputs of two high-pass filters.

Here, each of the above high-pass filters 25a (or 25b)
The configuration itself is basically the same as that of the high-pass filter shown in FIG.
(or 11b1.11b2) and capacitor 12a
1,12a2 (or 12b1. 12b2) and
Resistors 11a3, 11a4 (or 11b3゜ob<
), and the analog switch (21a) is used to switch the resistor connection for time constant switching.

21b).

The configuration of the above-mentioned high-pass filter device will be further explained below along with its operation.

First, to explain the initial state of the circuit of this example, each switch Sa1 in the analog switches 21a and 21b
, Sa2 and Sb1. Both Sb2 are on, and the time constants of the first high-pass filter 25a and the second high-pass filter 25b are kept small (time constant Tz).

Switches 20□ and 202 serve as switches for starting the operation of these high-pass filters 25a and 25b, which are turned on synchronously, and switch 20 in particular serves as an input switch for the acceleration difference from the accelerometer.

Therefore, for the circuit in the above initial state, when these switches 2Ch and 202 are turned on synchronously,
A differential signal of manual acceleration is input from the terminal 94 to each of the high-pass filters 25a, 25b, and a constant voltage +■ is input to the delay circuits 23a, 23b.

Here, the delay circuits 23a and 23b of this example are such that the former delay circuit 23a is turned on after a delay time a, and each switch Sa1. Sa
2 is turned off, and the latter delay circuit 23b is turned on after a delay time b (τb>τa), and each switch sb1. It is provided to turn off sb2.

As described above, the time-series changes in the state of the output from the adder circuit in the high-pass filter device of this example are as follows.

(a) From the operation start time to to the delay time τa During this period, the time constant of the first high-pass filter 25a is a small time constant T1 given by the resistors 11a1, 11a3 and the capacitor 12a1, and the second The time constant of the high-pass filter 25b is the resistor 11b, ,
11b3 and a small time constant T1 given by capacitor 12b1.

(b) From delay time a to delay time τb During this time, each switch Sa1 of the analog switch 21a
, Sa2 are switched off, the time constant of the first high-pass filter 25a is in the state of a large time constant T2 given by the resistor 11al and the capacitor 12a1, but when the other second high-pass filter 25b is The constant is a small time constant TI given by the same resistor 11b1.1lb3 and capacitor 12b1 as in (a) above.
continues to be in this state.

(c) After delay time τb From this point on, each switch Sa of the analog switch 21a
1 and Sa2, the switches "bl" and "Sb2" of the analog switch 21b are also turned off, so the time constant of the first high-pass filter 25a is equal to that of the resistor 1.
1a1 and the capacitor 12a1 (same as in (b) above), and the time constant of the other second high-pass filter 25b is also given by the resistor 11bl.
and the capacitor 12b, resulting in a state with a dog time constant T2.

Next, the effects of the high-pass filter device of this embodiment that performs the above-described configuration 1 operation will be explained according to a specific example.

Now, the second and second high-pass filters 25a in FIG.
The time constants T, , T2 of 25b are set in the same manner as in the example shown in FIG. 7 above, and the frequency given by equation (1) is as follows.

Set the time constant of the high-pass filter in (2) and (3) above.
), and assume that a manual acceleration difference signal is input to the input terminal 94 in FIG.

FIG. 2(a) shows the input terminal 9. 1 [! (This shows the waveforms of the outputs 15a and 15b of the two first and second high-pass filters 25a and 25b when the signal zl is input, and at the time of the arrow 26 in the figure, the switch 201
．． 202 is turned on to start input (operation), and at the time point 19a, the time constant of the high-pass filter 25a becomes T1-
T2, and at time 19b, the time constant of the high-pass filter 25b is switched to T1-T2.

At the switching times 19a and 19b, each delay circuit 23
This is given by the settings of the timers a and 23b.

Here, in this example, the delay time due to this is a.

The relationship of τb is expressed as (τa - τb ) = 0.5 [s
ec] and the time constant of the first high-pass filter 25a is switched to T1-T2 when the absolute value of the acceleration signal derived from the manual input signal of 1 [Hzl from the terminal 94 is maximum. After 0.5 [sec], the time constant of the high-pass filter 25b is switched to T1-T2, and at this time, the acceleration signal is at its maximum absolute value, and the error in each signal is extremely large. The polarity is reversed.

Therefore, if the respective signals are added by the adder circuit 25c, the errors of opposite polarity will be canceled out as shown in the signal 15c in FIG. 2(b), and a highly accurate output waveform will be obtained after the delay time τb. This means that they will be exposed.

FIG. 2(b) shows the output waveform 1 of the high-pass filter 25b.
5b and the output waveform 15C of the adder circuit 25c are observed simultaneously, and from this figure, it can be seen that the adder circuit 15
It will be understood that the output waveform 15c of c becomes a highly accurate output instantaneously after the time constant 19b is switched.

In the explanation of Fig. 2 above, the time constant of the high-pass filter is explained as being switched when the absolute value of the acceleration signal is at its maximum. If the relationship between a and τb is set as τa - τb = 0.5 [sec] (that is, relative to the frequency f [Hzl] of the human input signal, no matter at what point the time constant is switched for the input, after the switching Stable output can be achieved instantly.

The above explanation assumes a relatively extreme condition, that is, a significantly large difference between T1 before the time constant change and T2 after the change, in order to help understand that the output of the high-pass filter device is quickly stabilized according to the present invention. Therefore, it will take a long time to stabilize for hand movements other than the above-mentioned IHz vicinity, but in practical detection of camera vibration conditions, it is necessary to use two or more high-pass filters as mentioned above. When used in combination, it is possible to obtain early stabilization of the output by removing the DC component and/or low frequency component from the AC component.
Furthermore, by selecting and setting the time constant, the
It is also necessary to ensure the continuity of the output with respect to the input in the entire camera shake band z, and this will be explained below.

That is, each high-pass filter 2 having the configuration shown in FIG.
5a, 25b, for example, resistor 11a1.11b
1 to 2.2 [MΩ] each, capacitor 12a1.1
2b1 is 1 [μF], and resistor 11a3.

11b3 is set to 486 [KΩ], and in order to equalize the magnitude of the output before and after the high-pass filter, resistor 11a2, IIJ is set to 2.2 [MΩ], and resistor lLa is set.
4.11b4 to 4111i [KΩ, and noise removal capacitor 12a2.12b2 to 200 [tt F
], DC components and extremely low frequency components are accurately removed from the manual acceleration signals of 2 to 12[)1z], and as described above, each high-pass filter 25a,
The time constant of 25b is 1 [Hzl half wavelength length 0.5[
By shifting by 5ecl (ra - τb = 0.5 [5ecl) and adding it after switching, camera shake near IHz is stabilized early, and the overall value is 1 to 12[)1z]
The hand acceleration signal was obtained with good continuity before and after the time constant switching.

Specifically, in a single filter that guarantees the continuity of the signal of 2 to 12) 1z, in this case, the above (
1) The frequency given by the formula is 0, 2, which can guarantee the continuity of the output of 1 to 12) 1z in the example of Fig. 7.
[H2] Compared to about
Waiting time due to time constant switching up to b 0.5 [5e
The time was shortened to about 3 seconds including cl.

Note that in the above configuration, for example, the resistor 11a5.

11b5 to 10 [KΩ, resistor 11c of adder circuit 25c
By setting 5 [KΩ], the adder circuit 25c adds the outputs of the high-pass filters 25a and 25b, and divides by 2.The magnitude of the output signal at the terminal 104 is equal to the magnitude of the input signal at the terminal 94. It is made equal to the magnitude of the AC component of the signal (excluding DC and extremely low frequency components).

It goes without saying that the present invention is not limited to the example illustrated in FIG. In the example shown in the figure, the time constant switching is performed electrically using a delay circuit, but in addition, the time constant switching switch may be integrated with the release of the camera, and a well-known mechanical control such as an escape wheel may be used. A mechanical switch drive control means that provides the above-mentioned delay time relationship (τa-τb) may be constructed by using a speed changer, etc., and the switch means for switching the time constant may be configured as shown in FIG. In addition to the on/off switching type, a variable resistor may be used to continuously change the time constant.

Furthermore, the object to which the high-pass filter device of the present invention is applied is not limited to the camera vibration detection system described in detail above, and even in the same system, only the circuit shown in FIG. Differential amplifier 5
．． It goes without saying that the integrator 7 and the high-pass filter device may be connected in this order to form a circuit.

(Effects of the Invention) According to the high-pass filter device of the present invention having the configuration explained by the various embodiments as described above, the DC component is removed from the input of the acceleration signal within the shortest possible time. The effect is that it becomes possible to obtain a suitable output.

Furthermore, when the high-pass filter device of the present invention is used in a camera pre-detection system or an image pre-prevention system, the system can be activated by the photographer holding the camera to take a picture and pressing a predetermined switch. The effect is that the proper state (the output state of the true integral output) is reached as soon as possible, and a preferable photographing operation can be realized.

[Brief explanation of the drawing]

Figure 1 is a block circuit diagram showing an example of the configuration of a high-pass filter device according to the present invention, Figure 2 (a),
(b) is a diagram showing signal waveforms of input and output of an acceleration signal in order to explain the effect of the high-pass filter device of FIG. 1. Figure 3 is a diagram for explaining the concept of an image blur prevention system for vertical camera shake, Figures 4 (a) and (b) are diagrams showing an example of the configuration of a conventional high-pass filter, and Figure 5 is an acceleration sensor. Figure 6 is a diagram showing the input and output signal waveforms of acceleration signals to explain the shortcomings of conventional high-pass filters, and Figure 7 is a diagram showing the waveforms of other conventional high-pass filters. FIGS. 8(a) and 8(b), which are diagrams showing an example of a general configuration, are diagrams showing input and output signal waveforms of an acceleration signal in order to explain the drawbacks of the high-pass filter shown in FIG. 7. 1: Camera body 2: Lens barrel 3a1.3b1: Accelerometer 3a2, 3b2: Accelerometer sensitivity direction 5: Differential amplifier 6; High pass filter 7: Integrator 8: Correction lens 9: Input terminal 10: Output terminal 11. 111,211,311 + resistance 12.112,
212, 312 + Capacitor 14: Operational amplifier 15. 215, 315: High-pass filter output waveform 2
16.311i: High-pass filter human waveform 217
．． 317: DC component 218.318: Output stability point $319: Time constant switching point 20: Manual switch 21: Analog switch 23:
Delay circuit 24: OR circuit 25a, 25b: High pass filter 25c: Addition circuit 26 Two-person starting point Fig. 2 <(
1)

Claims (1)

[Claims] A high-pass filter device for removing DC components and/or low frequency components from an AC input, the time constant of which is changeable from a small time constant set as an initial state to a subsequent large time constant. a plurality of high-pass filters connected in parallel to the AC input; a time constant changing means for independently changing the time constants of the plurality of high-pass filters from small to large after the plurality of high-pass filters start operating; and the time constant changing means. A high-pass filter device comprising: switch drive control means for changing the time constants of the plurality of high-pass filters according to a predetermined time series; and an adding circuit for adding the outputs of the plurality of high-pass filters. .