JPH0566446A - Camera provided with vibration proof function - Google Patents

Abstract

PURPOSE:To prevent the deterioration of an image caused by the unstableness of vibration-proof output in the case of a superslow shutter and to obtain a complete vibration proof effect when a camera fixing means is used. CONSTITUTION:Control means 24 and 25 are provided, which control so that the band of the low frequency area of vibration proof frequency characteristic may become narrow when a shutter speed is equal to or under a fixed shutter speed. When the shutter speed at that time is lower than the fixed shutter speed, that is, in the case of the superslow shutter such as '1/2', the time constant of a vibration detecting means is made small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration system having a drive means for displacing a correction optical means relative to a lens barrel based on an anti-vibration output from a vibration detection means, and a shutter speed of a camera. The present invention relates to an improvement of a camera with an image stabilization function, which includes a characteristic control unit that changes the image stabilization frequency characteristic of the image stabilization system.

[0002]

2. Description of the Related Art The prior art to which the present invention is applied will be described below.

In modern cameras, all the important operations for photographing such as exposure determination and focusing are automated, so that even a person who is inexperienced in operating the camera is unlikely to make a mistake in photographing. However, it was difficult to automatically prevent only the failure of shooting due to camera shake.

Therefore, in recent years, a camera capable of preventing a shooting failure due to the camera shake has been eagerly studied, and in particular, a camera capable of preventing the shooting failure due to a camera shake of a photographer. Is under development and research.

The camera shake during photographing is usually a vibration of 1 Hz to 12 Hz as a frequency, but at the time of releasing the shutter, it is possible to take a photograph without image shake even if such a shake occurs. As a basic idea for this, it is necessary to detect the vibration of the camera due to the camera shake and displace the correction lens according to the detected value. Therefore, in order to achieve the above-mentioned object (that is, a photograph can be taken without causing image blur even if the camera shake occurs), first, the camera vibration is accurately detected, and
It is necessary to correct the optical axis change due to camera shake.

In principle, this vibration (camera shake) is detected by a vibration sensor for detecting angular acceleration, angular velocity, angular displacement, etc., and an output signal of the sensor is integrated electrically or mechanically to determine the angle. This can be performed by mounting a camera shake detection unit that outputs displacement on the camera. Then, based on the detection information, the correction optical mechanism that decenters the photographing optical axis is driven to suppress the image blur.

Here, an outline of an image blur suppression system (anti-vibration system) using an angular displacement detector will be described with reference to FIG.

The example of FIG. 7 is a diagram of a system for suppressing the image shake caused by the camera vertical shake 61p and the camera horizontal shake 61y in the direction of the arrow 61 in the figure.

In the figure, 62 is a lens barrel, 63p, 63.
y is an angular displacement detection device for detecting the vertical displacement of the camera and the lateral displacement of the camera, and the respective angular displacement detection directions are indicated by 64p and 64y. Reference numerals 65p and 65y denote arithmetic circuits that calculate the signals from the angular displacement detectors 63p and 63y and convert them into corrected optical system drive signals. This signal drives the correction optical mechanism 66 (67p and 67y are drive parts thereof and 68p and 68y are correction optical position detection sensors) to ensure stability on the image plane 69.

8 to 12 show an example of the configuration of the angular displacement detecting device as the vibration sensor, which will be described below with reference to these drawings.

In FIGS. 8 to 11, reference numeral 51 is a base plate on which each component of the apparatus is mounted, and 52 is an outer cylinder having a chamber in which a later-described floating body 53 and liquid 54 are enclosed. 53
Is a floating body which is rotatably held around a shaft 53a by a floating body holding body 55 described later. The projection 53b has a slit-shaped reflecting surface, and is made of a permanent magnet material. Has been magnetized. Further, the floating body 53 is configured so that the rotational balance around the shaft 53a and the buoyancy force are balanced.

Reference numeral 55 denotes a floating body holding body which is fixed to the outer cylinder 52 while holding the floating body 53 via a pivot bearing 56 described later. Reference numeral 57 denotes a U-shaped yoke attached to the base plate 51, which forms a closed magnetic circuit together with the floating body 53.
A winding coil 514 is arranged between the floating body 53 and the yoke 57 and is fixedly provided to the outer cylinder 52. Reference numeral 58 is a light emitting element (iRED) that generates light when energized, and
1 is attached. Reference numeral 59 denotes a light receiving element (PSD) whose output changes depending on the position of the received light, which is attached to the main plate 51. The light emitting element 58 and the light receiving element 59 constitute an optical angular displacement detection means of a method of transmitting light via the projection (reflection surface) 53b of the floating body 53.

Reference numeral 510 denotes a mask arranged on the front surface of the light emitting element 58, which has a slit hole 510a for transmitting light. 511 is a stopper member attached to the outer cylinder 52,
The rotation is regulated so that the floating body 53 does not rotate beyond a predetermined range.

The rotatably holding of the floating body 53 is performed as follows. That is, as shown in FIG. 9 (AA cross section of FIG. 8), a pivot 512 having a vertically sharp tip is press-fitted in the center of the floating body 53. On the other hand, pivot bearings 56 are provided at the tips of the U-shaped upper and lower arms of the floating body holding body 55 so as to face each other inward, and the sharp tips of the pivots 512 are fitted into the pivot bearings 56. The floating body is retained.

Reference numeral 513 denotes an upper lid of the outer cylinder 52, which is seal-bonded by a known technique using a silicone adhesive or the like so that the liquid 54 is enclosed in the outer cylinder 52.

In the above-mentioned structure, the floating body 53 does not generate rotational moment due to the influence of gravity in any posture, and the pivot shaft 53a is rotated about the rotational shaft 53a so that the load is not substantially applied. In addition to having a symmetrical shape, it is made of a material having the same specific gravity as the liquid 54. In reality, it is impossible to have an unbalance component of zero, but since the shape error only acts as an unbalance due to the difference in specific gravity, it is practically sufficiently small, and the SN ratio of friction against inertia is extremely good. Is easy to understand.

In such a structure, even if the outer cylinder 52 rotates about the rotary shaft 53a, the internal liquid 54 remains stationary with respect to the absolute space due to inertia. Therefore, the floating body 53 in the floating state does not rotate, and thus the outer cylinder is not rotated. 52 and the floating body 53 rotate relative to each other around the rotary shaft 53a. These relative angular displacements can be detected by an optical detecting means using the light emitting element 58 and the light receiving element 59.

Now, in the apparatus having the above-mentioned structure,
The detection of the angular displacement is performed as follows.

First, the light emitted from the light emitting element 58 passes through the slit hole 510a of the mask 510 and is applied to the floating body 53, where it is reflected by the slit-shaped reflecting surface of the protrusion 53b and reaches the light receiving element 59. During the transmission of the light, the light becomes substantially parallel light due to the slit hole 510a and the slit-shaped reflecting surface, and an image without blurring is formed on the light receiving element 59.

Since the outer cylinder 52, the light emitting element 58, and the light receiving element 59 are all fixed to the base plate 51 and move integrally, the relative angular displacement movement between the outer cylinder 52 and the floating body 53 is performed. When occurs, the slit image on the light receiving element 59 moves by an amount corresponding to the displacement. Therefore,
The output of the light receiving element 59, which is a photoelectric conversion element whose output changes depending on the position of the received light, becomes an output proportional to the positional displacement of the slit image, and the output is used as information for the outer cylinder 52.
The angular displacement of can be detected.

By the way, as described above, the floating body 53 is made of a permanent magnet material having the same specific gravity as that of the liquid 54, which is formed as follows, for example.

When a fluorine-based inert liquid is used as the liquid 54, a plastic material is used as a filler in the base, and fine powder of a permanent magnet material (for example, ferrite) is contained in the base 54 to adjust the content rate. It is easy to set the specific gravity to the same level as the specific gravity "1.8" of the liquid when the content rate is around 8%. After the floating body 3 is molded with such a material or simultaneously magnetized in the direction of the shaft 53a, the floating body 53 has a property as a permanent magnet.

FIG. 11 is a sectional view taken along line BB of FIG. 8 showing the relationship among the floating body 53, the yoke 57 and the winding coil 514.

As shown in the figure, the floating body 53 is magnetized in the direction of the shaft 53a. In this figure, the upper side is magnetized to the N pole and the lower side is magnetized to the S pole. The magnetic line of force from the N pole is a U-shaped yoke 5
A closed magnetic circuit that passes through 7 and enters the S pole is formed, and if a current is applied to the winding coil 514 arranged in this magnetic path from the back side of the paper to the front side as shown in the figure, Fleming's left-hand rule is followed. The winding coil 514 receives a force in the direction of arrow f. However, as described above, the winding coil 7 has the outer cylinder 5
Since it is fixed with respect to No. 2, it cannot move, and therefore a force acts in the direction of the arrow F which is its reaction, and the floating body 53 is driven by the force. It goes without saying that this force is proportional to the current flowing in the winding coil 514, and the direction of the force also works in the opposite direction if the current is passed in the opposite direction. That is, in the above structure, the floating body 53 can be freely driven.

The spring force exerted on the floating body 53 by this driving force is, in principle, a force that maintains the floating body 53 in a fixed posture with respect to the outer cylinder 52 (that is, moves integrally). If the force is strong, the outer cylinder 52 and the floating body 53 move as a unit, causing a problem that relative angular displacement does not occur for the intended angular displacement, but the driving force (spring force)
Is sufficiently small with respect to the inertia of the floating body 53, it can be configured to respond to angular displacement of a relatively low frequency.

FIG. 12 is a diagram showing an electric circuit of the angular displacement detecting device as described above.

Current-voltage conversion amplifiers 515a and 515b
(And resistors R33 to R36) are reflected light 5 of the light emitting element 58.
16. Photocurrents 517a and 51a generated in the light receiving element 59 by 16
7b is changed to a voltage, and the differential amplifier 518 (and the resistor R3
7-40) are the current-voltage conversion amplifiers 515a, 51
The output difference of 5b, that is, the angular displacement (the relative angular displacement movement between the outer cylinder 52 and the floating body 53) is obtained. This output is connected to resistor 51
9a, 519b divides the output to an extremely small output, and the current is input to the drive amplifier 520 (and the resistor R41 and the transistors TR11 and TR12) that flow a current through the winding coil 514, and the negative feedback (the differential amplifier 518 outputs the floating body). 53
Of the winding coil 514 and the floating body 53 so that the coil returns to the center.
Setting the magnetization direction of the liquid 54), the liquid 54
A sufficiently small spring force (driving force) is generated with respect to the inertia of.

Summing amplifier 521 (and resistors R42-4)
5) finds the sum of the amplifiers 515a and 515b (the total amount of received light of the reflected light 516 from the light emitting element 58 of the light receiving element), and outputs the output to the drive amplifier 522 (and the resistors R47 to R48) that cause the light emitting element 58 to emit light. , Transistor TR
13 and the capacitor C11).

The light emitting element 58 changes its light emission amount extremely unstablely due to the temperature difference. However, if the light emitting element 58 is driven by the total light receiving amount as described above, the total photocurrent output from the light receiving element 59 is increased. Is always constant, and the differential amplifier 518
The angular displacement detection sensitivity of is extremely stable.

FIG. 13 shows the required angular displacement detecting device.
FIG. 5 shows a graph (output with respect to input angular displacement), and the gain 582G has an angular displacement detection characteristic (flat characteristic with constant output with respect to input) from “0.1 Hz” or higher. As described above, since the camera shake has a frequency of about "1 Hz" to "2 Hz", it seems that integration of "1 Hz" or more should be performed as the angular displacement detection characteristic.
When the angular displacement detection characteristic is set to "1 Hz" or higher as shown in 3G, the phase 583p is "1H" regardless of the gain 583G.
In the vicinity of “z”, the angular displacement detection characteristics are not sufficient,
The phase 583p is "1 Hz", and is shifted by ψ583 (arrow 585). Therefore, the goal of the anti-vibration camera is "to prevent image blur by using a long focal length lens".
Therefore, accurate vibration isolation cannot be performed with such a large phase shift. Therefore, the phase 58 in the camera shake frequency band
A characteristic of using a small 2p shift [ψ582 (arrow 584)] and a large time constant (a larger time constant as the break point of the gain 582G curve in the board diagram is on the lower frequency side) is used.

As described above, in order to change the time constant of the angular displacement detecting device, the resistor 519b in FIG. 12 may be adjusted. For example, in order to increase the time constant, the resistor 51 should be adjusted.
9b may be reduced (the driving force of the winding coil 514 may be reduced).

FIG. 14 is a structural diagram of a servo angular acceleration sensor as another vibration sensor.

In FIG. 14, reference numeral 523 denotes an outer frame bottom portion, and the support portion 5 fixed integrally with the outer frame bottom portion 523.
24 and ball bearings 525 with low friction such as ball bearings
a and 525b support both ends of the shaft 526, and the shaft 526 supports the coils 527a and 52e.
A seesaw 528 to which 7b is attached is swingably supported.

Above and below the coils 527a and 527b and the chassis 528, magnetic circuit boards 530a and 530b and lids, which are separated from them, and permanent magnets 531a and 53, are provided.
1b, 532a, 532b are arranged facing each other,
The magnetic circuit boards 530a and 530b also serve as the lid portion of the outer frame as described above. Permanent magnets 531a, 531b, 532
a and 532b are mounted on magnetic circuit back plates 533a and 533b fixed to the bottom of the outer frame 523, respectively.

Further, the coil 527a of the above-mentioned seesaw 528.
A slit plate 534 forming a slit 534a penetrating in the thickness direction is provided on the top of the magnetic circuit board 530 which also functions as a lid portion of the outer frame above the slit 534a.
A photoelectric displacement measuring instrument 535 such as SPC (Separate Photo Diode) is arranged at a, and a light emitting element 536 such as an infrared light emitting diode is arranged on the magnetic circuit back plate 533a below the slit 534a. There is.

In the above structure, assuming that the angular acceleration a acts on the outer frame of FIG. 14 as indicated by the arrow 537, the seesaw 528 relatively tilts in the direction opposite to the angular acceleration a. The deflection angle can be detected by the position of the beam on the displacement measuring device 535 from the light emitting element 536 through the slit 534a.

By the way, the permanent magnets 531a and 531 are
The magnetic flux from b is respectively permanent magnets 531a and 531b → coils 527a and 527b → magnetic circuit boards 530a and 530.
b → coils 527a, 527b → permanent magnets 532a, 5
32b, the magnetic fluxes from the other permanent magnets 532a and 532b are respectively permanent magnets 532a and 532b → magnetic circuit back plate 5
33a, 533b → passes through the permanent magnets 532a, 532b to form a closed magnetic circuit as a whole, and the coil 52
A magnetic flux in a direction perpendicular to 7a and 527b is formed. By providing a control current to the coils 527a and 527b, it is provided so that the seesaw 528 can be moved to both sides along the deflection direction of the angular acceleration a according to Fleming's law.

FIG. 15 shows an example of the configuration of an angular acceleration detection circuit used in the servo angular acceleration sensor having the above configuration.

This circuit comprises a displacement detection amplifier 538 for amplifying the output from the displacement detector 535, and a compensation circuit 539 for making this feedback circuit a stable circuit system.
And a drive circuit 540 that further current-amplifies the amplified output from the displacement detection amplifier 538 to energize the coils 527a and 527b, and the coils 527a and 527b are connected in series.

In this example, the coil 527 is used.
a, 527b is energized, the external angular acceleration a
The winding direction of the coils 527a, 527b and the polarities of the permanent magnets 531a, 531b, 532a, 532b are set so that a force is generated in the direction opposite to the swing direction of the seesaw 528.

Explaining the operating principle of the servo angular acceleration sensor having the above structure, if an angular acceleration a is applied to the angular acceleration sensor having the above structure from the outside as shown in FIG. The force causes the outer frame to swing relatively in the opposite rotational direction, so that the slit 534a provided in the chassis 528 moves in the L direction. For this reason, the center of the light beam incident on the displacement detector 535 from the light emitting element 536 is displaced, and the displacement detector 535 produces an output proportional to the displacement amount.

The output is the displacement detection amplifier 53 as described above.
8 is further amplified by the drive circuit 540 through the compensating circuit, and the current is amplified by the coils 527a and 527b.

As described above, when a control current is applied to the coils 527a and 527b, a force is generated in the direction of the external angular acceleration a in the R direction, which is the opposite direction to the L direction, and the displacement is caused in the displacement. The control current is adjusted and generated so that the light flux incident on the detector 535 returns to the initial position when the external angular acceleration a is not applied.

At this time, the value of the control current flowing through the coils 527a and 527b is proportional to the rotational force applied to the seesaw 528, and the rotational force applied to the seesaw 528 has the origin at the seesaw 528. Since it is proportional to the returning force, that is, the magnitude of the external angular acceleration a, the current is applied to the voltage V through the resistor 541.
By reading as, for example, the magnitude of the angular acceleration a as the control information necessary for the image blur suppression system of the camera or the like can be obtained.

FIG. 16 is a diagram more specifically showing the angular acceleration detection circuit of FIG.

In FIG. 16, the amplification amplifier 538a and the resistors 538b and 538c are the displacement detection amplifier 538 of FIG.
The position of the photocurrent from the displacement measuring device 535 is detected by voltage conversion and amplification. Capacitor 539a and resistor 5
39b and 539c correspond to the compensation circuit 539, and include a drive amplifier 540a, transistors 540b and 540c, and a resistor 5
40d, 540e, 540f are coils 527a, 527
This corresponds to the drive circuit 540 that drives the drive b.

The angular acceleration obtained as described above is secondarily integrated by a well-known integrating circuit to obtain angular displacement information, and the correction optical mechanism is driven based on the angular displacement information as in the case of the angular displacement detection device. Anti-vibration can be performed. That is, as the vibration detecting means (vibration sensor) for detecting camera shake, an angular accelerometer and a calculating means (integrating circuit) are included.

FIG. 17 shows a board diagram of the required integral characteristic. The gain 586G has the integral characteristic (second order integral characteristic of 40 [dB / dec]) from "0.1 Hz" or more. Then, such integration characteristics are shown in FIG. 18, in which the operational amplifiers 590a and 590b are connected to the resistors 592a and 592b,
This can be realized by a circuit or the like in which first-stage integrators in which capacitors 591a and 591b are negatively fed back in parallel are connected in two stages in series. Then, when the output of the angular accelerometer is input to the terminal 593, the angular displacement detection characteristic is obtained from the terminal 594.

The characteristic of FIG. 17 is the ratio of the output of the terminal 594 when it is input to the terminal 593 and the output, and the resistors 592a and 592b and the capacitors 591a and 591b.
The time constant (from which Hz the integral characteristic is given in this case) is determined from the above relationship, and the time constant increases as the resistance value and the capacitance of the capacitors 591a and 591b increase.

As described above, the camera shake is "1 Hz" to "2".
Since the frequency is about "Hz", the integration characteristic is "1H.
It seems that it is sufficient to integrate "z" or more, but if the characteristic is such that "1 Hz" or more is integrated as shown in the gain 587G of FIG. It does not have the characteristic (phase delayed by 90 [dg] with respect to the input angular velocity), and "1H
z ”is displaced by ψ587 (arrow 589), and with such a large phase displacement, accurate image stabilization cannot be performed. Therefore, the shift of the phase 586p [ψ
586 (arrow 588)] is small, and a characteristic with a large time constant of 586G is used.

FIG. 19 is a view showing the arrangement of the correction optical mechanism that is preferably used in such a system.
5 is two directions perpendicular to the optical axis and perpendicular to each other [pitch direction 5
46p and yaw direction 546y (corresponding to 61p and 61y)]. The structure is shown below.

In FIG. 19, a fixed frame 547 for holding the correction lens 545 is a polyacetal resin (hereinafter referred to as POM).
It is possible to slide on the pitch slide shaft 549p through a slide bearing 548p such as the above). Further, the fixed frame 547 is sandwiched by a pitch coil spring 551p coaxial with the pitch slide shaft 549p and held near the neutral position. The pitch slide shaft 549p is the first holding frame 55.
It is attached to 0.

The pitch coil 552p mounted on the fixed frame 547 includes a pitch magnet 553p and a pitch yoke 5.
The fixed frame 547 is placed in a magnetic circuit composed of 54p, and the fixed frame 547 is driven in the pitch direction 546p by passing a current. The pitch coil 552p is provided with a pitch slit 555p, and the light emitting element 55
6p (infrared light emitting diode iRED) and light receiving element 557p
Due to the (semiconductor position detection element PSD) connection, the fixed frame 5
The position of 47 in the pitch direction 546p is detected.

A slide bearing 548y such as POM is fitted to the first holding frame 550, and a yaw slide shaft 549 is provided.
It can slide on the housing 558 to which y is attached. Since the housing 558 is attached to the lens barrel (not shown), the first holding frame 550 can move in the yaw direction 546y with respect to the lens barrel. Also, the yaw slide shaft 54
A yaw coil spring 551y is provided coaxially with 9y, and is held near the neutral position like the fixed frame 547.

A yaw coil 55 is attached to the fixed frame 547.
2y is provided, and a yaw that sandwiches the yaw coil 552y is provided.
The fixed frame 547 is also driven in the yaw direction 546y in association with the magnet 553y and the yaw yoke 554y. Above yo
The coil 552y is provided with a yaw slit 555y, and the yaw direction 546 of the fixed frame 547 is the same as the pitch direction.
The position of y is detected.

In FIG. 19, light receiving elements 557p, 55
The output of 7y is amplified by amplifiers 559p and 559y, and the coil (pitch coil 5
52p, yaw coil 552y), the fixed frame 5
47 is driven and the outputs of the light receiving elements 557p and 557y change. Here, when the driving direction (polarity) of the coils 552p and 552y is set to a direction in which the output of the light receiving elements 557p and 557y becomes smaller, a closed system (closed loop) is formed, and the outputs of the light receiving elements 557p and 557y become almost zero. Stabilizes at

The compensating circuits 560p and 560y are shown in FIG.
9 is a circuit that further stabilizes the system, and is an addition circuit 563.
p and 563y are circuits that add command signals 562p and 562y that are input to the amplifiers 559p and 559y, and drive circuits 561p and 561y are coils 552p and 552y.
It is a circuit that supplements the applied current of.

A command signal 562 is externally supplied to the system as described above.
When p and 562y are given, the correction lens 545 causes the command signal 562p and 562p in the pitch direction 546p and the yaw direction 546y.
It is driven very faithfully to 562y.

FIG. 20 is a diagram showing the driving means for driving the correction optical mechanism in more detail. Here, the pitch direction 54 is used.
Only 6p will be described.

Current-voltage conversion amplifiers 563a and 563b
The light emitting element 556p causes the light receiving element 557p (resistor R
1 and R2), and the differential amplifier 565 converts the photocurrent generated in each current-voltage conversion amplifier 563a, 5 into a voltage.
The difference signal represents the position of the correction lens 545 in the pitch direction 546p. As described above, the current-voltage conversion amplifiers 563a and 563b, the differential amplifier 5
65 and the resistors R3 to R10, the amplifier 559p of FIG.
Are configured.

The amplifier 566 adds the command signal 562p to the difference signal of the differential amplifier 565, and has a resistor R1.
1 to R14 form the adding circuit 563p shown in FIG. The resistors R15 and R16 and the capacitor C1 are well-known phase advance circuits, which correspond to the compensating circuit 560p in FIG. 19 and stabilize the system.

The output of the adder circuit 563p is the compensation circuit 5
It is input to the drive amplifier 567 via 60p, where the drive signal of the coil 552p is generated, and the correction lens 545 is displaced. The drive amplifier 567, the resistor R17 and the transistors TR1 and TR2 form a drive circuit 561p shown in FIG.

The addition amplifier 568 obtains the sum of the outputs of the current-voltage conversion amplifiers 563a and 563b (the total amount of light received by the light receiving element 557p), and the drive amplifier 569 that receives this signal.
Drives the light emitting element 556p accordingly. Above, the addition amplifier 568, the drive amplifier 569, the resistor R18
A driving circuit for the light emitting element 556p is constituted by R22 and the capacitor C2 (not shown in FIG. 19).

The light emitting element 556p described above changes its light projection amount extremely unstablely with temperature and the like, and accordingly the differential amplifier 5
Although the position sensitivity of 65 changes, the light emitting element 556p is driven by the above-mentioned drive circuit so that the total amount of received light becomes constant as described above.
If you control the position sensitivity will not change.

FIG. 21 is a diagram showing the structure of the correction optical mechanism using a variable apex angle prism.

In FIG. 21, 570 has a high refractive index,
For example, it is a silicon-based liquid, and two flat glass 57
It is sealed without bubbles by 1p and 571y and a polyethylene film 572. The flat glass 571p is held by the pitch holding frame 573p, and the pitch holding frame 573 is held.
p is rotatably fixed around the pitch shaft 574p. The flat glass 571y is held by a yaw holding frame 573y, and the yaw holding frame 573y is fixed around a yaw shaft 574y.

The pitch and yaw holding frames 573p and 573y are respectively provided with a pitch coil 575p and a yaw coil 575y, and these coils are fixed pitch and yaw.
Magnets 576p, 576y, pitch, yo-yoke 5
Since it is placed in the closed magnetic circuit formed by 77p and 577y,
By supplying currents to the pitch and yaw coils 575p and 575y, respectively, the pitch and yaw holding frames 573p and 573y are rotationally driven around the pitch and yaw axes, respectively.

The pitch and yaw holding frames 573p, 573
Displacement detection light receiving element 5 is attached to each of arms 578p and 578y of y.
79p and 579y are attached to the infrared light emitting elements 580p and 580y, which are fixed, to holes 581p,
Rotation around the pitch axis 574p and the yaw axis 574y is detected by the squeezed light beam radiated through 581y. Known position control is also performed between the displacement detection light receiving elements 579p and 579y and the pitch and yaw coils 575p and 575y. This has been described in the slide type correction optical mechanism, and a description thereof will be omitted.

In the above structure, the pitch holding frame 5
When 73p rotates around the pitch axis and the flat glass 571p tilts around the pitch axis 574p, the liquid 57 having a high refractive index is obtained.
The ray passing through 0 is decentered in the direction of arrow 546p,
When the yaw holding frame 573y rotates around the yaw axis and the flat glass 571y tilts around the yaw axis 574y, the light beam is eccentric in the direction of arrow 546y.

By the way, when the vibration detecting means (vibration sensor) having a large time constant is used as in the above-mentioned vibration isolation system, the following drawbacks occur.

First, the fact that the time constant is large means that it takes a long time for the output to stabilize. For example, when the break point in FIG. 13 is “0.1 Hz”, the time constant is “1.59” and “2” is required until the output stabilizes to some extent.
Seconds have to wait, during which the photographer has to hold the camera. I will explain why you have to wait while holding the camera.When a large shake such as re-holding the camera occurs after inputting the anti-vibration switch, the input vibration causes the dynamic range of the angular displacement detection device and the angular accelerometer to change. This is because the vibration angle will be exceeded, and stable blur angle detection cannot be performed unless the image stabilization is newly reset.

Next, the gain of the integrating circuit of this characteristic (characteristic having a large time constant) is "1H" shown by the broken lines in FIGS.
z ”or more, the gain of an integrating circuit having a characteristic of integrating 583G, 5
As shown by arrows 595 and 596, the band below the camera shake (1 Hz or less) is amplified compared to the 87G (1 in FIG. 17).
Therefore, the following error is also shown.

Gravity, disturbance, impact, etc. are also applied to the vibration detecting means such as the angular displacement detecting device and the angular accelerometer, so that extremely low frequency noise exists. In the angular accelerometer, if such an output is integrated by the integrating circuit of FIG. 18, this noise will be amplified. Further, in the angular displacement detection device, it can be easily understood that the floating body is difficult to return to the center (unstable) because the driving force (centripetal force) of the winding coil is weakened.

FIG. 22 shows the case where the anti-vibration camera is used in a state including the above error, and the correction optical mechanism is driven by the output of the vibration detecting means including the error with respect to the actual camera shake indicated by the sine wave 597. Waveform 598 of the movement of the correction lens in the case
Indicate. The difference 5100 between the camera shake 597 and the waveform 598 is the residual blur amount after image stabilization, and the residual blur amount 5101 during film exposure 599 is, in the case of an angular accelerometer, the pole of the vibration detection means amplified by the integrating circuit. Only low-frequency noise components, and in the case of the angular displacement detection device, only extremely low-frequency components that make the floating body unstable are generated.

Due to this error, in rare cases, the image blur may not be sufficiently corrected during photography.

Although there are the above two drawbacks, "1 /
Slow shutter speeds such as 8 "are not frequently used for shooting. And, in such a slow shutter shooting, it is time to carefully take a picture, and not in an urgent shooting environment such as "miss a shutter opportunity". Therefore, the waiting time does not matter so much during such a shooting.

The problem is that it is necessary to hold the camera and wait even during normal use (normal shutter speed such as 1/30 ...), and one frame per frame taken with such a shutter speed. In particular, there is a possibility that image blur reduction due to low frequency noise will be insufficient.

In recent years, when the camera is simplified, such as automatic exposure and automatic focus, and shooting is easy, it is fatal to have to endure the above problems in order to enjoy the merit of image stabilization. It can be said to be a drawback.

Therefore, by providing control means for changing the time constant of the vibration detecting means in correspondence with each shutter speed, the waiting time at the time of regular photographing such as "1/30" shutter speed is reduced, and Attempts have been made to enable accurate image blur correction.

For example, in addition to the characteristics of the integrating circuit for integrating "0.1 Hz" or more, or the angular displacement detecting device, "0.7 H"
A characteristic that integrates "z" or more is added, for example, "1/60"
In the shutter speed, the characteristic is that it integrates "0.7 Hz" or higher, or the characteristic of the angular displacement detection device that detects angular displacement of "0.7 Hz" or higher.

The reason why the characteristic of integrating "0.7 Hz" or more will suffice will be described. When the vibration detecting means having this characteristic is used, as shown in FIG.
On the other hand, the movement of the correction lens 5103 is out of phase.
(This is because the phase 583p, 5 of the characteristic of the vibration detecting means for detecting the hand shake of “1 Hz” or more shown in FIGS.
87p has a phase shift of 5 even in the camera shake band of "1 Hz" or higher.
It is understood from the fact that 83p and 587p are generated. Therefore, the corrected image plane blur amount 5104 has an error by the phase difference between the actual blur 5102 and the movement 5103 of the correction lens. The error 5105 at the "1/8" shutter speed is equal to or larger than the blur correction allowance, but the error 5106 at the "1/60" shutter speed is within the blur correction allowance.

As can be easily understood from FIG. 23, the faster shutter speed can make the time constant of the vibration detecting means smaller, for example, "1/150" shutter speed.
For vibration, it is better to change to a vibration detection characteristic that detects camera shake above 1.1 Hz. As a result, the regular shutter speed
When shooting with a long focus lens, you can shoot with an extremely short waiting time. Until now, when using a long-focus lens, camera shake would occur unless the shutter speed was higher than "1/300".
It is possible to shoot even with a slow shutter such as "1/60", and it is also possible to shoot with a super slow shutter of "1/8" if you carefully prepare.

By the above-described method of "reducing the time constant of the vibration detecting means when the shutter speed becomes faster", the image stabilization system waits during normal operation (shooting of "1/60", "1/30", etc.). You can shoot without being aware of time,
At the time of the slow shutter such as "/ 8", since the photographer takes the image of the subject carefully, there is no need to worry about the waiting time for image stabilization.

[0084]

However, when a slower shutter speed ("1/2" or the like) is used, the "instability of the output of the vibration detecting means due to the increase of the time constant" is photographed. Influences.

FIG. 24 is a diagram for explaining this.

Movement 5 of Correction Lens for Hand Shake 597
The fact that 98 is unstable is the same as in the case of FIG. Then, shooting with the "1/8" shutter speed (arrow 59
Image deterioration due to unstable output of the vibration detection means at 9)
In contrast, shooting with the "1/2" shutter speed (arrow
The image deterioration 5106 in the case of (5105) is larger as the exposure time is longer. Then, if the image deterioration becomes large in this way, the image deterioration will exceed the allowable range, and the anti-vibration effect cannot be expected so much.

Further, when such a long-time exposure (super slow shutter of "1/2" or less) is performed, a tripod is usually used in order to eliminate the influence of camera shake.

However, in a camera equipped with an image stabilization system, image deterioration may occur even when the camera is equipped with a tripod in long-time exposure to eliminate camera shake.

This is the movement 598 of the correction lens in FIG.
This is due to the output instability of the vibration detection means (due to the large time constant), and the output instability of the vibration detection means is corrected even when there is no camera shake due to the use of a tripod. Is driven to cause image deterioration.

That is, when the tripod is used, camera shake (a phenomenon in which the camera shakes around the tripod seat due to camera release shock, mirror up / down, a frequency of "10 Hz" or more different from hand shake) is vibration-proof. Using a camera on a tripod can suppress it more than using a conventional camera on a tripod, but the image deterioration due to unstable output of the vibration detection means becomes large, and it is said that a sufficient image stabilization effect cannot be obtained. The problem arises.

In view of the above points, an object of the present invention is to prevent image deterioration due to instability of anti-vibration output at the time of super slow shutter and to obtain sufficient anti-vibration effect when using the camera fixing means. It is to provide a camera with an anti-vibration function.

[0092]

The present invention is provided with a control means for controlling so that the band of the low frequency region of the image stabilization frequency characteristic becomes narrow below a certain shutter speed.

[0093]

When the shutter speed at that time is slower than the constant shutter speed, that is, when the super slow shutter is "1/2" or the like, the time constant of the vibration detecting means is made small.

[0094]

FIG. 1 is a diagram showing the manner of changing the time constant in the first embodiment of the present invention.

In FIG. 1, the horizontal axis 11 is the shutter speed of the camera, which is determined by the photographer performing external operations such as photometric means and dials built in the camera.
The vertical axis 12 indicates the shake detection frequency, and for example, "0.1 H
z ”(in the figure, shutter speeds“ 1/8 ”and“ 1 / ”
15 "), 582G, 582p in FIG.
7 has the vibration detection characteristics shown by 586G and 586p,
At "1 Hz" (shutter speed "1/150"), 583G and 583p in FIG. 13 and 587G and 58 in FIG.
It shows that the vibration detection characteristic is 7p.

In FIG. 1, the time constant curve 13 has a higher shake detection frequency as the shutter speed is faster (smaller time constant), and has a lower shake detection frequency as the shutter speed is slower (time constant is longer). Wide band in large and low frequency range)
Is the same as before, but the shutter speed is "1/8"
When it becomes slower, the blur detection frequency becomes higher again, and the band of the low frequency region becomes narrower.

FIG. 2 shows the characteristic of the angular displacement detecting device as the vibration detecting means, and the shutter speed is "1/6".
When it is "0", the shake detection frequency in Fig. 1 is "0.7 Hz", and the characteristic in Fig. 2 is the characteristic shown by the gain 21G and the phase 21p. As described above, it is possible to shoot without doing so. And
When the shutter speed is "1/8", the shake detection frequency in FIG. 1 is around "0.1 Hz", and the gain 582G in FIG.
The characteristic is the phase 582p. When the shutter speed is "1/2", the shake detection frequency in FIG.
z ”again, and the characteristics of the gain 22G and the phase 22p shown in FIG. 2 are obtained.

In the angular displacement detection device, the shake detection frequency can be changed by adjusting the variable resistor 23 shown in FIG. 3. When the resistance value of the variable resistor 23 is reduced, the shake detection frequency becomes "0.1 Hz."", Etc., and the resistance value increases, the blur detection frequency increases, such as" 0.5 Hz. "

The variable resistance 23 is controlled by the Tv information output circuit 24 and the time constant table 25, which are control means, so that its resistance value can be changed.

The Tv information output circuit 24 outputs the shutter speed determined by the photometric means or an external operation, and the time constant table 25 has the relationship shown in FIG. 1, and the shake detection frequency is obtained from the shutter speed. The resistance value of the variable resistor 23 is controlled so that the shake detection frequency is obtained.

As described above, the shutter speed is "1/2".
When the blur detection frequency is increased again (the band of the low frequency region is narrowed) in the case of the super slow shutter such as, the following advantages occur.

As shown in FIG. 24, a "1/2" super slot
When the shutter is used, the image deterioration 5106 becomes large, and this is because the output of the vibration detecting means is unstable (the time constant is large and the tele detection frequency is low). However, in this embodiment, in the super slow shutter, the time constant of the vibration detecting means is made small again (the resistance value of the variable resistor 23 in FIG. 3 is made large) to reduce the output instability. Prevents image deterioration. Of course, in this case, FIG.
As shown by 583p in FIG. 4, the phase shift becomes large and the image deterioration due to this becomes large, but as shown in FIG.
The image deterioration 32 due to the phase shift is "1/2" shown in FIG.
Image deterioration due to instability of the output of the vibration detecting means at the time of photographing by the shutter speed. An error with an amplitude smaller than 5106 is repeated, and the image deterioration amount on the film surface is not large. (The time constant of the vibration detecting means is large, and it is larger than the image deterioration that occurs when shooting with the "1/8" shutter speed. However, it is normal when shooting with the "1/2" shutter speed while handheld. (It is much smaller than the image deterioration that occurs without image stabilization).

When a tripod is used, vibration does not occur near "1 Hz" because there is no camera shake, and a phase shift due to a small time constant (phase shift near "1 Hz").
Also, since camera shake such as camera shake has a relatively high frequency (around "10 Hz"), it is not affected by a phase shift around 1 "Hz", and image stabilization is performed accurately, so there is no image deterioration. You can get a picture.

Although the case where the time constant of the angular displacement detecting device is controlled by the shutter speed has been described above, the case where the angular accelerometer is used as the vibration detecting means will be described below as the second embodiment of the present invention. ..

The angular accelerometer detects the camera shake angular acceleration applied to the camera and secondarily integrates it to obtain the camera shake displacement. By controlling the time constant of this integration circuit, the angular displacement detection device described above The same effect as the case can be obtained.

FIG. 5 is a diagram showing the characteristics of the second-order integration circuit. For example, the gain 586G is the characteristics of the integration circuit that integrates components of "0.1 Hz" or higher, and the output of the angular accelerometer is "0.1 H
It is as described above that the above "z" is integrated and converted into an angular displacement.

Here, in the "1/60" shutter speed, the gain is 41G and the phase is an integral characteristic of 41P, and in the "1/8" shutter speed, the gain is 586G and the phase is 586p. As shown in the characteristics, the time constant is increased, and in the "1/2" shutter speed, the gain is set to 42G and the phase is set to 42P so that the time constant is decreased again.

FIG. 6 is a circuit diagram showing an example of an integrating circuit for changing the time constant in this way. What is different from FIG. 18 is that the resistors 43a and 43b are variable resistors and the control means Tv.
The resistance value is controlled by the information generating circuit 24 and the time constant table 25.

In FIG. 6, when the resistance values of the resistors 43a and 43b are reduced, the time constant is reduced.
41p, the time constant increases as the resistance value is increased, and the integration characteristics are changed to 586G and 586p in FIG.

The time constant table 25 in this case has the same contents as in FIG. 1, and when the shutter speed is fast, the resistance values of the variable resistors 41a and 41b are controlled to be small in order to reduce the time constant. If the shutter speed becomes slow, the resistance values of the variable resistors 41a and 41b are increased to increase the time constant. Then, the super slow shutter ("1 /
2)), the resistance value is reduced to reduce the time constant again to prevent image deterioration due to unstable output of the vibration detecting means.

In the above description, the example in which the vibration detecting means is constituted by the angular accelerometer and the second-order integrating circuit has been described. However, even when the vibration detecting means is constituted by an angular velocity meter such as a vibration gyro and the first-order integrating circuit. If the time constant of the first-order integration circuit is changed in accordance with the relationship between the shutter speed and the shake detection frequency shown in FIG. 1, the same effect can be obtained, and the correction optical mechanism has a mechanical integration action. Needless to say, the time constant may be changed by the speed and the position loop gain of the correction optical mechanism. In any case, if the time constant is reduced again in the case of the super slow shutter, Needless to say, the same effect can be obtained.

According to each of the above-mentioned embodiments, the time constant of the vibration detecting means is made small at the time of normal photographing (shutter speed is "1/60" etc.) (in order to start the means early),
In the slow shutter mode (shutter speed is "1/8", etc.), the time constant is increased. When the shutter speed is "1/2", etc., the time constant is made small again (because the image stabilization cannot be done anyway in the camera shake band), and the output is unstable due to the large time constant. Therefore, the image deterioration is prevented.

For example, even if a tripod is used for the super slow shutter, if the time constant of the vibration detecting means is large, the output drift causes image deterioration. However, by using the above-mentioned configuration, Since camera shake is not caused by a tripod, and camera shake caused by vibrations such as mirror up and down is corrected by the image stabilization system, an accurate image can be obtained.

[0114]

As described above, according to the present invention,
Below a certain shutter speed, a control means is provided to control the band of the low frequency region of the image stabilization frequency characteristic so that the shutter speed at that time is slower than the certain shutter speed, that is, "1/2". In the case of a super slow shutter such as the one described above, the time constant of the vibration detecting means is reduced. Therefore, it is possible to prevent image deterioration due to instability of the image stabilization output at the time of the super slow shutter and to obtain a sufficient image stabilization effect when the camera fixing means is used.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship of changing a time constant in each embodiment of the present invention.

FIG. 2 is a board diagram showing the characteristics of the angular displacement detecting device as the vibration detecting means in the first embodiment of the present invention.

FIG. 3 is a circuit diagram showing a configuration for changing a time constant in the first embodiment of the present invention.

FIG. 4 is a diagram illustrating image deterioration in the first embodiment of the present invention.

FIG. 5 is a board diagram showing characteristics of an angular accelerometer as a vibration detecting means in the second embodiment of the present invention.

FIG. 6 is a circuit diagram showing a configuration for changing a time constant in the second embodiment of the present invention.

FIG. 7 is a perspective view showing a schematic configuration of a conventional vibration isolation system.

FIG. 8 is a plan view showing an angular displacement detection device which is one of conventional vibration detection means.

9 is a cross-sectional view taken along the line AA of FIG.

10 is a perspective view of the angular displacement detection device shown in FIG.

11 is a sectional view taken along line BB of FIG.

12 is a circuit diagram showing an electrical configuration of the angular displacement detection device shown in FIG.

13 is a board diagram showing characteristics of the angular displacement detection device of FIG.

FIG. 14 is an exploded perspective view showing the structure of a servo angular accelerometer which is one of conventional vibration detecting means.

FIG. 15 is a block diagram showing an electrical configuration of the servo angular accelerometer of FIG.

16 is a circuit diagram specifically showing the electrical configuration of FIG.

FIG. 17 is a graph showing the characteristics of the servo angular accelerometer of FIG.
FIG.

FIG. 18 is a circuit diagram showing a configuration for determining an integral characteristic of the servo angular accelerometer of FIG.

19 is a diagram showing a mechanical and electrical configuration of a correction optical mechanism in the image stabilization system of FIG.

20 is a circuit diagram specifically showing the electrical configuration shown in FIG.

21 is a perspective view showing another example of the correction optical mechanism in the image stabilization system of FIG. 7. FIG.

FIG. 22 is a diagram illustrating image deterioration when a conventional vibration detecting means having a large time constant is used.

FIG. 23 is a diagram for explaining image deterioration when a conventional vibration detecting means capable of changing a time constant is used.

FIG. 24 is a diagram for explaining a problem when shooting is performed by a super slow shutter using a conventional vibration detecting means.

[Explanation of sign]

 23 variable resistance 24 Tv information output circuit 25 time constant table 43a, 43b variable resistance 63p, 63y angular displacement detector

Claims (2)

[Claims] 1. A correction optical unit which is disposed in a lens barrel for holding a lens group and decenters an optical axis of the lens group,
Vibration detecting means for detecting vibration applied to the lens barrel,
An anti-vibration system having a drive means for displacing the correction optical means relative to the lens barrel based on an anti-vibration output from the vibration detection means, and the anti-vibration system corresponding to a shutter speed of a camera. In a camera with an anti-vibration function equipped with a characteristic control means for changing the anti-vibration frequency characteristic, a control means for controlling the low-frequency band of the anti-vibration frequency characteristic to become narrow at a certain shutter speed or less. A camera with anti-vibration function, which is provided. 2. The anti-vibration function according to claim 1, wherein the control means is means for reducing the time constant of the vibration detection means when the shutter speed at that time is slower than a constant shutter speed. With camera.