Image shake compensating device

An image shake compensating device includes a compensating member for compensating for an image shake taking place on an image forming plane of an optical instrument; a detecting circuit for detecting, through the displacement state of the compensating member, the shaking state of the optical instrument causing the image shake; and a driving circuit for driving the compensating member in response to an output of the detecting circuit.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an image shake compensating device for an optical 
monitoring apparatus, an optical instrument such as a still camera or the 
like. 
2. Description of the Related Art 
Image shake compensating devices of varied kinds have recently been 
proposed for still cameras. Still cameras equipped with such devices are 
being developed. 
The known image shake compensating devices are generally arranged to 
include a shake detector which detects a shaking state (acceleration, 
speed of displacement) of an optical instrument such as a camera; a 
compensating optical system which is movable in the direction of 
offsetting an image shake resulting from shaking of the optical instrument 
in such a way as to prevent any image shake on the image forming plane of 
the optical instrument; a computing device for computing a degree of shake 
compensation to be made by the compensating optical system on the basis of 
the output of the shake detector; an actuator which drives the 
compensating optical system on the basis of the output of the computing 
device; a servo detector which detects the moving extent and the position 
of the compensating optical system; and a compensating optical system 
driving control device for driving the actuator on the basis of a 
difference between the output of the computing device and the output of 
the servo detector. The control system of the conventional image shake 
compensating device is as shown in a block diagram in FIG. 24 of the 
accompanying drawings. In FIG. 24, a compensating optical system moving 
degree detector represents the above-stated servo detector. 
The conventional image shake compensating device which includes the 
above-stated control system necessitates the optical instrument to use the 
shake detector which detects shaking of the optical instrument and the 
compensating optical system moving degree detector which detects the 
moving degree of the compensating optical system. This requirement not 
only increases the size of the instrument but also requires use of a 
complex electronic circuit arrangement for complex control. This causes an 
increase in cost of the image shake compensating device and eventually in 
cost of the instrument. 
SUMMARY OF THE INVENTION 
This invention is directed to the solution of above-stated problem of the 
prior art. It is therefore an object of the invention to provide a novel 
image shake compensating device which can be arranged more compactly and 
at a lower cost than the conventional device. 
It is another object of the invention to provide a novel image shake 
compensating device which permits reduction in size and cost of an optical 
instrument which is equipped with the image shake compensating device. 
To attain the above-stated object, an image shake compensating device 
arranged according to the invention comprises: compensating means for 
compensating for an image shake occurring on the image forming plane of an 
optical instrument; detecting means for detecting, through the 
displacement of the compensating means, a shaking state of the optical 
instrument which is causing the image shake; and driving means for driving 
the compensating means in response to the output of the detecting means. 
Other objects and features of this invention will become apparent from the 
following detailed description of embodiments thereof taken in connection 
with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to the drawings, embodiments of this invention are described as 
follows: 
FIG. 1 is a oblique front view showing the mechanical structural 
arrangement of an image shake compensating device arranged according to 
the invention as a first embodiment thereof. FIG. 2 is a partially 
sectional view taken transversely across the essential parts of the same 
device, showing the device as viewed from below. FIG. 3 is an oblique view 
of the essential parts of a detector and those of a compensating optical 
system together with a compensating optical system driving actuator, 
showing them as in a state of being taken out from the arrangement of FIG. 
1. 
Referring to FIGS. 1 and 2, front and rear base plates 21 and 22 are 
fixedly disposed within an optical instrument such as a camera or the like 
and are arranged to carry a compensating optical system 30 and 
compensating optical system driving actuators 33 and 34. The front base 
plate 21 is provided with an optical path hole 21a and a hole 21b for 
carrying the compensating optical system driving actuator 33. The rear 
base plate 22 is provided with an optical path hole 22a (see FIG. 2) and a 
hole 22b for carrying the compensating optical system driving actuator 34. 
Further, a first detector 31 is attached to recessed parts formed on one 
side of the front and rear base plates 21 and 22. Meanwhile, a second 
detector 32 (see FIGS. 2 and 3) is attached to the edge parts of the base 
plates 21 and 22 on the same side. The first detector 31 is arranged to 
detect the rotary displacement of the optical instrument taking place 
around its horizontal axis. The first detector 31 faces sidewise as shown 
in FIGS. 1 and 3. The second detector 32 is arranged in the same manner as 
the first detector 31 but is positioned to face downward for the purpose 
of detecting the rotatory displacement of the optical instrument taking 
place around the vertical axis thereof. The further details of the 
detectors 31 and 32 will be described later. 
The compensating optical system 30 is composed of a variable angle prism 
and is disposed within a space formed between the front and rear base 
plates 21 and 22. The optical system 30 is carried jointly by the front 
and rear base plates 21 and 22. The variable angle prism which forms the 
compensating optical system 30 includes: an annular front frame 19; a 
circular front glass plate 15 which is secured to the front frame 19; an 
annular rear frame 20 which is disposed a given distance away from the 
front frame 19; a circular rear glass plate 16; a bellows type flexible 
tubular member 17 (see FIGS. 2) which is fitted on the end parts of the 
outer circumferences of the front and rear frames 19 and 20 and extends 
between these frames 19 and 20; and a transparent liquid 18 (see FIG. 2) 
which is sealed in a sealed chamber surrounded by the front glass plate 
15, the rear glass plate 16 and the flexible tubular member 17. 
As shown in FIG. 3, projections 19b and 19c which are provided with pin 
holes for rotatably inserting vertical pins 19a are formed at uppermost 
and lowermost parts of the outer circumference of the front frame 19. The 
pins 19a (only the lower pin 19a is shown in FIG. 2 and only the upper pin 
19a in FIG. 3) are erected on a pair of upper add lower arms 21c. (Only 
the lower arms 21c is shown in FIG. 2.) The front frame 19 is thus carried 
by the front base plate 21 in such a way as to be rotatable on the pins 
19a. 
A light receiving element carrying plate 27 to which a light receiving 
element 14 included in the second detector 32 is attached is mounted on 
the lower projection 19c of the front frame 19. The light receiving 
element carrying plate 27 is arranged to serve as a connector for 
connecting the light receiving element 14 to the substrate of other 
circuits, a power source, etc. 
A short, rightward protruding arm 19d is provided on one side edge of the 
front frame 19 as shown in FIG. 2. (An arm 20b which is of the same shape 
as this arm 19d is provided on the rear frame 20 as shown in FIG. 3.) The 
shaft 33a of the first compensating optical system driving actuator 33 
(hereinafter referred to as the first actuator) is secured to the arm 19d. 
The first actuator 33 is a so-called voice coil type electromagnetic 
plunger. The actuator 33 is composed of a cylindrical yoke 26 which is 
fixedly fitted into the hole 21b of the front base plate 21; a permanent 
magnet 24 fixedly positioned within the yoke 26; a pole piece 25 mounted 
on the permanent magnet 24; a coil 23 secured to the shaft 33a. The 
actuator causes the front frame 19 to turn round on the pin 19a with its 
shaft 33a moved backward by an electromagnetic force generated between the 
permanent magnet 24 and the coil 33 when a current is applied to the coil 
23 in the forward direction. 
Projections 20d (see FIG. 2) and 20c (FIG. 3) which resemble the 
above-stated projections 19b and 19c protrude from the outer 
circumferential face of the rear frame 20. In the projections 20d and 20c 
are provided pin holes which are arranged to permit a pair of horizontally 
extending pins 20a (see FIGS. 2 and 3) to be rotatably inserted therein. 
As shown in FIG. 2, the pins 20a are erected on arms 21d which extend 
backward from the rear side of the front base plate 21 (FIG. 2 shows only 
one of the pins 20a). The rear frame 20 is carried by the front base plate 
21 to be rotatable on the pins 20a. In other words, the rear frame 20 can 
be turned round on a horizontal axis which is perpendicular to the optical 
axis of the compensating optical system 30. Further, as shown in FIG. 3, a 
light receiving element carrying plate 28 to which the light receiving 
element 14 of the first detector 31 is attached is mounted on the 
projection 20c. The light receiving element carrying plate 28 is arranged 
to serve also as a connector. 
As shown in FIG. 3, a short arm 20b protrudes from an upper end part of the 
outer circumferential face of the rear frame 20. The shaft 34a of the 
second actuator 34 is secured to the arm 20b as shown in FIG. 2. 
The second actuator 34 is a so-called voice coil type electromagnetic 
plunger of the same structure as that of the first actuator 33 and 
includes: a bottomed cylindrical yoke 26 which is fixedly fitted in the 
hole 22b of the rear base plate 22; a permanent magnet 24 which is secured 
to the yoke 26; a pole piece 25 which is mounted on the permanent magnet 
24; and a coil 23 which is secured to a shaft 34a. When a forward current 
is applied to the coil 23, the shaft 34a is moved forward as viewed on 
FIG. 3. This causes the arm 20b of the rear frame 20 to be pushed forward. 
As a result, the rear frame 20 turns round clockwise on the pins 20a, 
i.e., clockwise on a horizontal axis. 
The variable angle prism device arranged in the above-stated manner 
operates as follows: When at least either the front frame 19 or the rear 
frame 20 is turned round on the pins 19a or 20a, the front glass plate 15 
or the rear glass plate 16 slants relative to a vertical plane. Then, rays 
of light incident on the front glass plate 15 deflect. As a result, an 
image on the image forming plane moves perpendicularly to the optical axis 
to compensate for an image shake. 
Next, referring again to FIGS. 1, 2 and 3, the detectors 31 and 32 are 
arranged and function as follows: Since these detectors 31 and 32 are 
arranged in the same manner, the components parts of them are indicated by 
the same reference numerals. Each of the detectors 31 and 32 is an angular 
displacement detector of the kind called a hydrostatic sensor. In the case 
of the image shake compensating device of this embodiment, they serve as 
shake detectors for detecting a shaking state of the optical instrument 
(rotatory displacements on the horizontal and vertical axes and also 
function as servo detectors for detecting the moving degree of the 
compensating optical system. 
In FIGS. 1 to 3, a reference numeral 1 denotes a box-like member which is 
secured to the front and rear base plates 21 and 22. A tubular member 2 is 
secured to the box-like member 1 and is filled with a transparent liquid, 
which is sealed therein. A vane-wheel shaped floating body 4 is arranged 
to be rotatable within the transparent liquid on a horizontal axis (in the 
case of the first detector 31) or on a vertical axis (in the case of the 
second detector 32). Four mirrors 5 which are provided with slits are 
attached respectively to the outer faces of the angular tube like bearing 
part of the floating body 4. A floating body carrying member 6 is provided 
with a pivot shaft for rotatably carrying the floating body 4 and is 
fixedly fitted into a groove formed in the inner circumferential wall of 
the tubular member 2 as shown in FIGS. 2 and. 3. A yoke 7 forms an 
electromagnet which is arranged to induce the vane part of the floating 
body 4 to a given position and to have it in repose there. Yokes 8 and 9 
are connected to the two ends of the yoke 7 and have their ends in contact 
with the outer face of the tubular member 2. A floating body positioning 
device supporting base 10 is provided with a arcuate groove 10a which is 
formed to have its center on the shaft 4a of the floating body 4 and is 
arranged to permit slidable insertion therein of a pin la protruding from 
the inner wall face of the box shaped member 1. The support base 10 is 
also arranged to carry the yokes 7, 8 and 9. A coil 11 is fitted on the 
yoke 7 and forms the electromagnet jointly with the yoke 7. A leaf spring 
12 is mounted on the box member 1 and has an arm part 12a arranged to urge 
the floating body positioning device supporting base 10 to move away from 
the tubular member 2. Light emitting elements (IRED) 13 are secured to the 
box member 1. Light receiving elements 14 are secured to light receiving 
element carrying plates 27 and 28 which are respectively secured to the 
front and rear frames 19 and 20 of the variable angle prism device as 
shown in FIG. 3. Masks 29 are disposed in front of the light receiving 
elements 14 and are secured to the light receiving element carrying plates 
27 and 28. 
The yokes 7 to 9 and the coil 11 jointly form a floating body positioning 
device which is arranged to induce the floating body 4 to a given position 
and to cause it to be in repose there. When the coil 11 is energized, a 
magnetic circuit is formed in a loop of the yoke 7 - the yoke 8 - the 
floating body 4 - the yoke 9 - the yoke 7. The fore end of the vane shaped 
part of the floating body 4 is attracted to a position where it is opposed 
to the fore ends of the yokes 8 and 9 to be electro-magnetically retained 
there as shown in FIG. 2. 
The floating body positioning device supporting base 10 is arranged such 
that its position relative to the tubular member 2 can be changed by 
moving the arcuate groove 10a relative to the pin 1a, i.e., by turning 
round the support base 10 on the shaft 4a of the floating body 4. 
Therefore, the positions of the fore ends of the yokes 8 and 9 relative to 
the tubular part 2 can be changed. To enable the support base 10 to be 
turned round, the support base 10 is provided with a gear part 10b which 
is formed on the outer circumferential edge of the support base 10. The 
gear part 10b engages a gear which is not shown. The base 10 thus can be 
turned round by rotating this gear. 
The light receiving elements 14 are formed by a known semiconductor 
position detecting element (PSD). The light receiving element carrying 
plates 27 and 28 are arranged to serve also as connectors for transmitting 
the output of each of the light receiving elements to a detecting circuit 
which will be described later. 
Each of the detectors 31 and 32 mentioned in the foregoing is arranged to 
detect a shake (angular displacement) of the optical instruments based on 
the following principle. When the optical instrument moves round its 
horizontal or vertical axis, the tubular member 2, the light emitting 
element 13 and the light receiving element 14 which are in one body with 
the optical instrument turn round on the horizontal or vertical axis along 
with the optical instrument. However, the force of inertia of the 
transparent liquid 3 disposed within the tubular member 2 keeps the 
floating body 4 in its original position by preventing it from turning 
round on the shaft 4a. Therefore, the mirrors 5 attached to the floating 
body 4 are brought into a state of being turned round relative to the 
light emitting and receiving elements 13 and 14. As a result, the 
direction of light which comes from the mirrors 5 to the light receiving 
element 14 changes. The light receiving element 14 then produces an output 
showing the rotated position of the optical instrument. 
The floating body positioning device which consists of the coil 11 and the 
yokes 7 to 9 is arranged to bring the arm 4b of the floating body 4 into a 
stationary state in a position at the fore ends of the yokes 8 and 9 
before the detector 31 or 32 begins to operate. In other words, the 
detectors 31 and 32 are arranged to be reset with the floating body 4 set 
in its initial position. More specifically, the coil 11 is energized to 
have the magnetic circuit of the Yoke 7 - the yoke 8 - the floating body 4 
- the yoke 9 - the yoke 7 formed immediately before the detector begins to 
operate. This brings the floating body 4 into its "zero" position as shown 
in FIG. 2 before the detector is reset. 
FIG. 4 shows in outline the electrical control arrangement included in the 
image shake compensating device of this embodiment. The control 
arrangement consists of various circuits related to the light emitting 
elements 13 and the light receiving elements 14 which are disposed within 
the detectors 31 and 32; circuits for controlling the electromagnets of 
the floating body positioning devices included in the detectors 31 and 32; 
circuits for controlling a power supply to the coil of the compensating 
optical system actuator; a microcomputer (hereinafter referred to as CPU) 
56 which is arranged to control the above-stated various circuits. 
Referring to FIG. 4, two diodes 14a and 14b form a light receiving element 
14. When the light of the light emitting element 13 is received by the 
light receiving element 14, the diode 14a produces an output voltage A and 
the other diode 14b an output voltage B according to the incident position 
of the light. In FIG. 4, the light receiving element 14 is shown as being 
composed of two diodes as a model. In actuality, however, a known PSD is 
arranged to produce two outputs A and B indicating the position of the 
incident light. 
A detecting circuit 52 includes an addition-and-subtraction circuit and a 
division circuit and is arranged to produce a signal indicating 
(A-B)/(A+B). Further, an output (A+B) of the detecting circuit 52 
represents the whole output of the light receiving element 14. Another 
output (A-B) of the circuit 52 represents the incident position of a light 
flux incident on the light receiving element 14 and also indicates whether 
or not the compensating optical system is following the detector. 
A light emitting element driving circuit 58 is arranged to control a 
current flow to the light emitting element 13. An electromagnet driving 
circuit 57 controls a current flow to the coil of the floating body 
positioning electromagnet. A start switch 60 is provided for causing an 
image shake compensating device to operate. An actuator driving circuit 53 
is arranged to control a current supply to the coils 23 of the actuators 
33 and 34. A reference numeral 56 denotes the CPU which is arranged to 
control these circuits. 
FIG. 5 is a flow chart showing a program to be executed by the CPU 56 of 
FIG. 4. FIGS. 6(a), 6(b) and 6(c) show the various states of the 
compensating optical system 30 and the detector 32. 
The following describes the operation of the image shake compensating 
device of this embodiment with reference to FIGS. 1 to 6(c). The detector 
32 and the compensating optical system 30 are assumed to be in repose in 
the state of FIG. 6(a) before the image shake compensating device begins 
to operate. 
Referring to FIG. 4, when a switch 60 is closed, the CPU 56 allows a timer 
which is included therein to operate as shown in FIG. 5. After that the 
electromagnet driving circuit 57 which is interlocked with the timer 
begins to operate. This causes a power supply to be effected to the 
electromagnet coils 11 disposed within the detectors 31 and 32. The power 
supply to the coils 11 continues until the operation of the timer comes to 
an end. With the coil thus energized, the yokes 8 and 9 are magnetized. 
The vane part of the floating body 4 is moved up to a position where it is 
in alignment with the fore ends of the yokes 8 and 9 and then comes to a 
stop there as shown in FIG. 2. The detectors 31 and 32 are reset by this. 
Then, if the optical instrument has not been shaken and swung on its 
horizontal or vertical axis, the light emitting element 13, the light 
receiving element 14, the mirror 5 and the variable angle prism device of 
the compensating optical system within each of the detectors 31 and 32 are 
respectively in their postures as shown in FIG. 6(a). Further, in FIGS. 
6(a) to 6(c), a reference numeral 40 denotes the photo-taking lens of the 
optical instrument and a numeral 41 the image forming plane of the optical 
instrument. Parallel pencils of rays "a", "b" and "c" incident on the 
variable angle prism device form an image at a point P on the optical 
axis. 
After the detectors 31 and 32 are reset as in the manner mentioned above, 
the CPU 56 causes the light emitting element driving circuit 48 to drive 
the light emitting element 13 to emit light. At this time, if the optical 
instrument is not shaking as mentioned above, the relative positions of 
the light emitting element 13, the mirror 5 and the light receiving 
element 14 are in the initial states as shown in FIG. 6(a). The 
compensating optical system is, therefore, not driven. 
When the optical instrument deviates (turns round) on the horizontal or 
vertical axis from the above-stated initial state, the tubular member 2 of 
the detector 31 or 32 comes to turn round on the axis of the floating body 
4. Meanwhile, however, the floating body 4 is kept in its original 
position by the force of inertia of the liquid 3 in the tubular member 2. 
As a result, a change takes place in the relative positions of the light 
emitting element 13 and the mirror 5. This causes a change in the position 
of the incident pencil of rays coming from the mirror 5 to the light 
receiving element 14. 
FIG. 6(b) shows the above-stated condition. Under this condition, the 
optical instrument is in a state of having been turned round on the 
vertical axis thereof (an axis parallel to the pin 19a). Accordingly, both 
the image forming lens 40 and the image forming plane 41 come to slant. 
The image on the image forming plane 41 moves from the initial image 
forming position P to a new position Q to give a so-called image shake. 
Then, since the incident position of the pencil of rays coming from the 
mirror 5 to the light receiving element 14 has changed, the light 
receiving element 14 produces from its two ends the output signals A and B 
according to the incident position. As a result, the detecting circuit 52 
produces an output (A-B)/(A+B). This output signal is supplied to the 
actuator driving circuit 53. This causes the actuator 33 to be excited. 
The front frame 19 of the compensating optical system 30 is turned round 
on the pin 19a to bring about a condition, for example, as shown in FIG. 
6(c), the parallel pencils of rays "a", "b" and "c" incident on the 
variable angle prism are refracted in such a way as to form the image 
obtained by the photo-taking lens at the point P. The image shake is thus 
compensated for by this. In this instance, when the front frame 19 of the 
compensating optical system 30 is turned round on the pin 19a, the light 
receiving element 14 which is arranged in one unified body with the front 
frame 19 within the detector 31 also turns round on the pin 19a. 
Therefore, the incident light coming from the mirror 5 to the light 
receiving element 14 also changes its position. The output of the 
detecting circuit 52 decreases accordingly as the turning degree of the 
front frame 19 increases. The movement of the compensating optical system 
30 is mechanically fed back to the detector 32. When the output of the 
detecting circuit 52 becomes zero (i.e., .vertline.A-B.vertline.=0), the 
action of the actuator driving circuit 53 comes to a stop. The actuator 33 
also stops operating. 
FIGS. 7, 8(a) and 8(b) show a second embodiment of the invention in which 
the detectors 31 and 32 of the first embodiment described above are 
modified. In the second embodiment, the compensating optical system is 
composed of the same variable angle prism device as that of the first 
embodiment. Therefore, details of the compensating optical system are 
omitted from description and the component parts of the compensating 
optical system are indicated by the same reference numerals as those used 
in FIGS. 1, 2 and 3. 
The following description of the second embodiment takes up one of two 
detectors 32A which are arranged in the same manner as each other but 
differ from the arrangement of the first embodiment: In FIGS. 7, 8(a) and 
8(b), the same component parts as those of the first embodiment are 
indicated by the same reference numerals. The detector 32A is a 
hydrostatic sensor like the detectors 31 and 32 of the first embodiment. 
In the case of the second embodiment, however, the detector 32A differs 
from the detector of the first embodiment in the following point: Unlike 
the first embodiment, the detector 32A is not arranged as a photo-electric 
conversion element for detecting a change in the relative positions of the 
floating body 4 and the tubular member 2. More specifically, the detector 
32A incorporates a semiconductor magnetoresistive element 301 therein. 
The semiconductor magnetoresistive element 301 is carried by an element 
support plate 29 which is disposed between the fore end part 9a of the 
yoke 9 and the arm 4b of the floating body 4 which is opposed to the fore 
end part 9a. When the arm 4b of the floating body 4 is in alignment with 
the fore end part 9a of the yoke 9 as shown in FIGS. 7 and 8(a), there is 
formed a magnetic circuit in a loop of: yoke 7 - yoke 9 - floating body 4 
- yoke 8 - yoke 7. Then, as shown in FIG. 8(a), a magnetic flux J passes 
the middle part of the semiconductor magnetoresistive element 301. 
Therefore, the resistance values obtained between the middle terminal 301c 
of the element 301 and one end terminal 301a and between the middle 
terminal 301c and the other end terminal 301b become equal to each other. 
Therefore, the output of the detecting circuit 52 becomes zero. However, 
when the positions of the floating body 4 and the yoke 9 relative to each 
other changes, the magnetic flux J comes to deflect from the middle part 
of the magnetoresistive element 301 toward the terminal 301a as shown in 
FIG. 8(b). Therefore, the electric resistance between the terminal 301c 
and the terminal 301a increases while the resistance between the terminals 
301c and the terminal 301b decreases. This causes the detecting circuit 52 
to product an output. 
FIGS. 9 and 10(a) to 10(c) show a third embodiment of this invention. In 
this case, the compensating optical system of the preceding embodiments is 
modified by way of example. The third embodiment uses, as the detector, 
the same hydrostatic sensor of the type incorporating a photo-electric 
conversion element as in the case of the first embodiment shown in FIGS. 1 
to 3. With respect to the detector arrangement, FIGS. 9 and 10(a) to 10(c) 
indicate the same component parts as those of the first embodiment with 
the same reference numerals. Meanwhile, the third embodiment employs a 
cantilever type compensating optical system, instead of the variable angle 
type prism device of the first embodiment. 
Referring to FIG. 9, a compensating lens 205 is carried by a flat lens 
holding frame 203. The lens holding frame 203 is carried in a 
cantilever-like manner by the fore ends of four flexible support rods 204 
which extend in parallel to the optical axis of the lens 205. Each of the 
flexible support rods 204 has its core made of a metal rod or a metal wire 
material. The core material is coated with an elastic expandable matter 
like a rubber material. The rear end of the support rod 204 is secured to 
a body frame 201 of an optical instrument such as a camera. Since the fore 
end of each support rod 204 is flexible in the direction perpendicular to 
the optical axis, the lens holding frame 203 is also movable in the same 
direction. 
Cut-out parts are formed in two sides of the lens holding frame 203. A coil 
213 and a yoke 212 of an actuator 211 for horizontal driving are disposed 
at one of the cut-out parts. At the other cut-out part are disposed a coil 
209 and a yoke 206 of an actuator 210 which is provided for driving in the 
vertical direction. The coils 213 and 209 of the actuators 211 and 210 are 
secured to the lens holding frame 203 through reels. The yokes 206 and 212 
of these actuators are secured to a stationary structural member of the 
optical instrument such as the body frame 201 or the like. As shown in 
FIGS. 9 and 10(a) to 10(c), the cross sections of these yokes are in the 
shape of the letter E. The yoke 206 consists of a middle piece which is 
inserted in the coil 209 and outside pieces which extend in parallel along 
the outside of the coil 209. To the inner walls of the outside pieces are 
secured permanent magnets 207 and 208 as shown in FIGS. 10(a) to 10(c). 
Each of the actuators 210 and 211 is composed of the yoke and the 
permanent magnets and the coil. The actuators are thus arranged to be 
capable of driving the lens holding frame 203 in the vertical and 
horizontal directions when the coils 209 and 213 are energized. 
The light receiving element 14 which is included in the detector 31 is 
secured to the back side of the lens holding frame 203. The light 
receiving element 14 is arranged to receive the reflection light of the 
mirror 5 which is attached to the floating body 4. 
The electrical arrangement of the image shake compensating device of this 
(the third) embodiment is the same as in the case of the second embodiment 
shown in FIG. 4 and, therefore, requires no description. 
FIGS. 10(a) to 10(c) show the mechanical arrangement of the image shake 
compensating device of FIG. 9 as in its various states. 
FIG. 10(a) shows the device as in a state of having no shaking of the 
optical instrument. In this state, the image forming plane 202, the lens 
205 and the lens holding frame 203 of the optical instrument are in 
parallel to a vertical plane which is perpendicular to the optical axis of 
the lens. The pencil of rays coming from the mirror 5 of the floating body 
4 to the light receiving element 14 is received at the middle part of the 
light receiving element 14. Therefore, the outputs A and B of the element 
14 which are produced from two ends of the element are equal to each other 
to give no output of the detecting circuit 52. Parallel rays of light 
"a"to "c" incident on the lens 205 form an image at the center P of the 
image forming plane 202 and show no image shake. 
FIG. 10(b) shows the device as in a state of having the optical instrument 
turned round clockwise on the horizontal axis thereof, which is 
perpendicular to the paper surface of the FIGS. 10. The image forming 
plane 202, the lens 205 and the lens holding frame 203 are also turned 
round together with the optical instrument. The parallel rays of light "a" 
to "c" incident on the lens 205 then form an image at a point Q thus 
showing an image shake. Under this condition, the floating body 4 within 
the detector 31 remains in its position of FIG. 10(a). This brings about a 
change in the relative positions of the mirror 5 and the light receiving 
element 14. The reflection light from the mirror 5 falls on a point 
deviating from the center of the light receiving element 14. As a result, 
the two end outputs A and B of the light receiving element 14 are no 
longer equal to each other. The detecting circuit 52 then produces an 
output (A-B)/(A+B). Therefore, the actuator driving circuit 53 drives the 
actuator 210 by allowing a current corresponding to the output of the 
detecting circuit 52 to flow to the coil 209 of the actuator 210. When the 
coil 209 is thus energized, the current of the coil 209 and the magnetic 
fields of the permanent magnets 207 and 208 interact to exert on the coil 
209 a downward force which is parallel to the axis of the coil. Therefore, 
the lens holding frame 203 is moved downward from the position of FIG. 
10(b) perpendicularly to the optical axis of the lens 205. The fore ends 
of the four flexible carrying rods 204 are then moved downward. The rods 
204 elastically warp. The lens 205 and the lens holding frame 203 come 
down to their positions as shown in FIG. 10(c). Then the image of the 
parallel pencils of rays "a" to "c" incident on the lens 205 moves from 
the point Q to another point P. The image is thus compensated for the 
shake. When the lens 205 and the lens holding frame 203 comes down to the 
positions of FIG. 10(c), the reflection light from the mirror 5 again 
falls on the middle part of the light receiving element 14. As a result, 
the output of the detecting circuit 52 becomes zero. The power supply to 
the coil 209 of the actuator 210 is cut off. Upon completion of image 
shake compensation, a shutter mechanism (not shown) is actuated. An 
exposure to the image forming plane is effected to complete a 
photographing operation. 
Next, a fourth embodiment of this invention is arranged as shown in FIG. 
11. In the drawing, the parts of the fourth embodiment which are arranged 
in the same manner as in the first embodiment are indicated by the same 
reference numerals and the details of them are omitted from the following 
description. 
In addition to the floating body positioning arrangement of the first 
embodiment described in the foregoing, the fourth embodiment is arranged 
to detect from the output of the detector the arrival of the compensating 
optical system at a limit point within its compensatable range; and to 
bring the compensating optical system to the middle position of the 
compensatable range by brining the floating body back to its initial 
position. 
To have the above-stated function added to the floating body positioning 
arrangement, the electrical control arrangement of the fourth embodiment 
includes means for changing the amount of power supply to the coil 11 
mentioned in the foregoing. 
The mask 29 which is disposed in front of the light receiving element 14 is 
provided with a laterally extending rectangular aperture 29a. The lateral 
width (i.e., vertical dimension as viewed on FIG. 2) of the aperture 29a 
of the mask 29 corresponds to the size of the compensatable action range 
of the compensating optical system. When the compensating optical system 
is moved up to the limit point of the compensatable action range, the rays 
of light coming from the mirror 5 to the light receiving element 14 fall 
upon the light receiving element 14 in a state of brushing one end edge of 
the aperture 29a of the mask 29. In this instance, a part of the incident 
light is eclipsed by the edge of the aperture 29a. The amount of light 
incident on the light receiving element 14 thus decreases. As a result, 
the output of the light receiving element 14 decreases to indicate that 
the compensating optical system is in the limit position of the 
compensatable action range. 
FIG. 11 shows in outline the electrical control arrangement of the image 
shake compensating device which is arranged as the fourth embodiment of 
the invention. The control arrangement comprises the circuits of varied 
kinds related to the above-stated light emitting and receiving elements 13 
and 14 disposed within each of the detectors 31 and 32; a control circuit 
for controlling the electromagnet of the floating body 
positioning/restoring device disposed within each of the detectors 31 and 
32; a circuit for controlling a power supply to the coil of the 
compensating optical system actuator; and a CPU 156 which is arranged to 
control the various circuits. 
Referring to FIG. 11, a detecting circuit 152 is formed by a 
addition/subtraction circuit. The circuit 152 is arranged to generate 
signals indicative of values (A-B) and (A+B). The output (A+B) of the 
detecting circuit 152 represents the whole output of the light receiving 
element 14. The output (A-B) represents the incident position of a light 
flux incident on the light receiving element 14 and also indicates whether 
or not the compensating optical system is following the detector. 
A received-light level detecting circuit 61 is formed by a known 
comparator. The circuit 61 is arranged to compare a reference level KVC 
set by a reference level setting device 62 with the signal (A+B) coming 
from the detecting circuit 152. When the level of the input signal (A+B) 
is lower than the reference level KVC, the received-light level detecting 
circuit 61 produces an output and supplies it to a light emitting element 
driving circuit 158. The light emitting element driving circuit 158 is 
arranged to increase the quantity of current supplied to the light 
emitting element 13 in accordance with the output of the detecting circuit 
152. An emitted-light level detecting circuit 63 is arranged to detect the 
amount of a current flowing from the light emitting element driving 
circuit 158 to the light emitting element 13 and to produce an output 
which corresponds to the detection value thus obtained. A determination 
circuit 64 is arranged to produce an output which indicates a difference 
between the output of the emitted-light level detecting circuit 63 and a 
level stored at an emitted-light level storing circuit 65 and to determine 
the state of the compensating optical system and that of the detector. The 
above-stated emitted-light level storing circuit 65 is arranged such that, 
when the variable angle prism device is located in the middle position of 
the compensatable action range so that the received-light detecting 
circuit 61 detects that the input signal (A+B) reaches the reference level 
KVC, the circuit 65 stores the output of the emitted-light level detecting 
circuit 63 produced at that time in response to a control signal m output 
from the CPU 156. A start switch 60 is arranged to cause the image shake 
compensating device to begin to operate and to serve also as a power 
supply switch for the optical instrument or as a function switch. 
The above-stated detector and the circuit group consisting of the 
emitted-light level detecting circuit 63, the emitted-light level storing 
circuit 65, the determination circuit 64 and the electromagnet driving 
circuit 57 jointly form floating body positioning control means for 
repositioning the compensating optical system by controlling the restoring 
action of the detector when a large shake exceeding the compensatable 
range of the compensating optical system or some unusual vibrations are 
inflicted upon the optical instrument. Further, in combination with this 
floating body positioning control means, the detecting circuit 152 and the 
actuator driving circuit 53 jointly form main control means for the 
above-stated actuator. 
FIG. 12 is a flow chart showing a program to be executed by the CPU 156 of 
FIG. 11. Further, the mechanical arrangement of the image shake 
compensating device of the fourth embodiment is identical with that of the 
first embodiment. Referring to FIGS. 1 to 3, 6, 11 and 12, therefore, the 
image shake compensating device of the fourth embodiment is described as 
follows: 
When the switch 60 of FIG. 11 is closed, the CPU 156 causes a timer 1 which 
is included in the CPU 156 to operate as shown in FIG. 12. Following that, 
the electromagnet driving circuit 57 which is interlocked to the timer 1 
is rendered operative. This causes a power supply to be supplied to the 
coil 11 of the electromagnet disposed within each of the detectors 31 and 
32. With the coil 11 thus energized, the yokes 8 and 9 are magnetized. 
Therefore, the vane part of the floating body 4 is moved to a position 
where it is in alignment with the fore ends of the yokes 8 and 9 and is 
then brought to a stop in this position as shown in FIG. 2. By this, the 
detectors 31 and 32 are reset. If the optical instrument is not shaken on 
its horizontal or vertical axis at that time, the light emitting element 
13 and the light receiving element 14 which are disposed within each of 
the detectors 31 and 32 and the variable angle prism device of the 
compensating optical system are respectively in their postures as shown in 
FIG. 6(a). 
After the detectors 31 and 32 are reset as mentioned above, the CPU 156 
causes the light emitting element driving circuit 158 to drive the light 
emitting element 13 to emit light, and brings the detecting circuit 52 and 
the actuator driving circuit 53 into an operable state. At that moment, if 
the optical instrument is not shaking as mentioned above, the relative 
positions of the light emitting element 13, the mirror 5 and the light 
receiving element 14 are in their initial states as shown in FIG. 6(a). 
Therefore, the level of the output (A-B) of the detecting circuit 152 is 
zero, and the actuator driving circuit 53 does not supply a current to the 
coil 23, so that the compensating optical system is not driven. 
When the optical instrument is shaken or turned round on its horizontal or 
vertical axis, the tubular member 2 of either the detector 31 or the 
detector 32 is turned round on the axis of the floating body 4 along with 
the optical instrument. However, the floating body 4 is retained in its 
original position by the force of inertia of the liquid 3 provided within 
the tubular member 2. As a result, a change occurs in the relative 
positions of the light emitting element 13 and the mirror 5. A light flux 
coming from the mirror 5 to the light receiving element 14 also changes 
its incident position accordingly. 
This condition is as shown in FIG. 6(b). The optical instrument is in a 
state of having been turned round on the vertical axis, which is in 
parallel to the pin 19a. Accordingly, the image forming lens 40 and the 
image forming plane 41 also slant. An image formed on the image forming 
plane 41 moves from the initial image forming position P to another 
position Q to bring about the so-called image shake. 
With the optical instrument shaken as shown in FIG. 6(b), the change in the 
positional relation between the mirror 5 and the light receiving element 
14 causes the output (A-B) of the detecting circuit 152 to be no longer 
zero. The actuator driving circuit 53 is driven according to the output 
(A-B) of the detecting circuit 152. Then, a current is supplied to the 
coil 23 of the actuator 33, so that the actuator 33 is driven. 
With the actuator 33 driven, the front frame 19 of the compensating optical 
system 30 is turned round on the pin 19a. The light receiving element 14 
which is in one body with the front frame 19 is also turned round on the 
same pin 19a. The positional relation between the mirror 5 and the light 
receiving element 14 changes from the state of FIG. 6(b) toward the state 
of FIG. 6(c). The shake detection output (A-B) of the detector 32 comes to 
decrease accordingly as the turning degree of the front from 19 increases. 
The input to the actuator driving circuit 53 also decreases accordingly as 
the front frame 19 turns round. The acting degree of the compensating 
optical system is mechanically fed back to the actuator driving signal. 
Assuming that the reflection light of the mirror 5 falls on the middle part 
of the light receiving element 14 when the front frame 19 of the 
compensating optical system 30 is turned round to the position of FIG. 
6(c), the driving action on the actuator 33 comes to a stop as the output 
(A-B) from the detecting circuit 152 then becomes zero. This brings the 
turning movement of the front frame 19 to a stop. At this instance, the 
image of the parallel pencils of rays "a" to "c" incident on the image 
forming plane 41 is formed at the point P to have the image thus 
compensated for the image shake. 
Generally, an optical instrument such as a camera or the like equipped with 
an image shake compensating device tends to become incapable of 
compensating for an image shake under the following conditions: 
(a) a shake of the camera with amplitude exceeding the compensatable range 
of the compensating optical system; and (b) in case that the camera at 
first shakes with a small degree of amplitude near the middle point of the 
compensatable range of the compensating optical system before it deflects 
to a great degree and, after that, it shakes with small amplitude in the 
deflected position. 
In the case of the shake (a), the compensating optical system correctly 
acts within the compensatable range but becomes completely incapable of 
compensating the instant the shake comes to exceed this range. Considering 
the camera shake in terms of an image shake occurring on the image forming 
plane, an image which has been kept in repose by the compensating action 
suddenly comes to deflect to a great extent at a point of time. Therefore, 
the compensating action rather gives an adverse effect of enlarging the 
image shake. Besides, the sudden image shake is disagreeable to the visual 
sensations when the image shake compensating device is mounted on a video 
camera, a binocular or the like. 
Meanwhile, in the case (b) above, the position of the compensating optical 
system is biased to one side of the compensatable range after the great 
deflection of the camera. The biased position then prevents the 
compensating optical system from moving if the camera is further deflected 
to a great degree next time. Therefore, the image shake compensating 
action cannot be adequately accomplished under this condition. Besides, in 
this instance, the compensating optical system driving actuator is 
continuously energized while the optical system is hardly movable. This 
wastes the electric energy to cause an increased consumption of the 
battery or the like. 
To avoid the enlargement of the image shake or the total inability of the 
compensating optical system in the case (a) or (b) described above, the 
image shake compensating device is preferably arranged as follows: Against 
the case (a), to avoid occurrence of a sudden image shake, the 
compensating optical system is controlled to lower its compensating speed 
accordingly as the optical system comes closer to the limit point of the 
compensatable range. Against the case (b), to enable the compensating 
optical system to perform the compensating action, the optical system is 
arranged to be slowly brought back to the middle point of the 
compensatable range after the first occurrence of the large deflection, so 
that the optical system can be prepared against a next occurrence of a 
large deflection. 
In the case of the image shake compensating device of the fourth 
embodiment, the compensating optical system is arranged, against the 
above-stated case (b), to be brought back to its initial position by the 
floating body positioning control means described in the foregoing when 
the optical system is in a position near to the limit point of the 
compensatable range thereof. 
In other words, when the compensating optical system is close to one of the 
limits of the compensatable range, for example, as shown in FIG. 13, the 
floating body 4 is slowly moved back to its initial position, as shown in 
FIG. 2, by the actions of the determination circuit 64 and the 
electromagnet driving circuit 57, in a manner as will be described later. 
With the floating body thus moved back to its initial position, the 
compensating optical system is ready for a next action. The image shake 
compensating action, therefore, always can be accomplished even in the 
case (b) mentioned above. 
For this purpose, the fourth embodiment is arranged to determine, from a 
change in the output of the light emitting element or from the output of 
the light receiving element, the position of the compensating optical 
system (to find whether or not it is close to the limit of the compensable 
range). The compensating optical system is controlled in the above-stated 
manner on the basis of the result of the determination. This enables the 
embodiment to perform image shake compensation even when complex 
vibrations are inflicted upon the optical instrument. 
More specifically, as has been described above, when the received-light 
level detecting circuit 61 detects that the output (A+B) of the detecting 
circuit 152 reaches the reference level KVC after the light emitting 
element driving circuit 158 starts the driving, the CPU 156 judges that 
the amount of light received by the light receiving element 14 reaches the 
reference value. Further, when the output (A-B) of the detecting circuit 
152 is below the prescribed level, the CPU 156 judges that light emitted 
from the light emitting element 13 enters almost the central portion of 
the light receiving element 14 and the detectors 31 and 32 are reset to 
the initial position, and causes the output of the emitted-level detecting 
circuit 63 to be stored in the emitted-light level storing circuit 65. 
On the other hand, during that period, the image shake compensating device 
is operating in such a manner as described above. The operation of the 
image shake compensating device continues until the switch 60 is turned 
off. However, when the compensating optical system reaches the limit 
position of the compensatable range as shown in FIG. 13, a light flux 
coming from the mirror 5 to the light receiving element 14 passes through 
the aperture 29a of the mask 29 by brushing the edge of the aperture 29a. 
Therefore, a part of the light flux is eclipsed by the edge of the 
aperture 29a. The quantity of light incident upon the light receiving 
element 14 thus decreases and, accordingly, the output (A+B) of the 
detecting circuit 152 also decreases. Since the amount of the input to the 
received-light level detecting circuit 61 decreases, if the input to the 
circuit 61 thus becomes less than the reference level KVC, the circuit 61 
produces an output for the light emitting element driving circuit 158. In 
response to this, a driving current applied to the light emitting element 
13 is increased. Then, the emitted-light level detecting circuit 63 
supplies the light emitting element driving current obtained at that time 
to the above-stated determination circuit 64. The determination circuit 64 
compares the currently detected value of the light emitting element 
driving current with the previous value of the light emitting element 
driving current obtained at the above-stated initial position and stored 
by the emitted-light level storing circuit. The circuit 64 thus determines 
the current position of the detector (i.e., the positional relation 
between the light receiving element 14, the light emitting element 13 and 
the mirror 5) and the position of the compensating optical system 30 from 
the result of comparison. The determination circuit 64 is thus arranged to 
produce an output when the compensating optical system is located near the 
limit of the compensatable range and also when the position of the 
compensating optical system is located outside the range. The circuit 64 
produces no output in all other cases. 
When the output of the circuit 64 is produced, the CPU 156 causes the 
built-in timer 2 and the electromagnet driving circuit 57 to operate. The 
electromagnet driving circuit 57 increases the current supply to the coil 
11 of the electromagnet according to the output of the circuit 64. This 
causes the vane part of the floating body 4 to be attracted and pulled to 
the position of the fore ends of the yokes 8 and 9. As a result, the 
detector 32 is reset to bring the compensating optical system back to its 
middle position. The electromagnet driving circuit 57 continues the power 
supply to the coil 11 until the counting operation of the timer 2 comes to 
an end. 
FIGS. 14 and 15 show in a diagram and a flow chart the electrical 
arrangement and the control program of an image shake compensating device 
arranged as a fifth embodiment of the invention. The mechanical 
arrangement of the image shake compensating device is identical with that 
of the first embodiment and, therefore, is omitted from the illustration. 
Referring to FIG. 14, the illustration includes a CPU 120; a light 
emitting element driving circuit 121; a detecting circuit 122 which is 
arranged to receive the output signals A and B of the light receiving 
element 14 and to produce outputs (A-B) and (A+B); a received-light level 
storing circuit 123; a determination circuit 124 which is arranged and 
functions in the same manner as the determination circuit 64 of the fourth 
embodiment shown in FIG. 11; and a division circuit 125 which is arranged 
to receive the output of the detecting circuit 122 and to produce an 
output (A-B)/(A+B). Circuit elements indicated by the same reference 
numerals as in FIG. 11 are identical with those of the fourth embodiment. 
Other circuits elements that are labelled the same as but indicated by 
different reference numerals from FIG. 11 as mentioned above are also 
arranged to do about the same functions as the corresponding elements 
shown in FIG. 11. Namely, the light emitting element driving circuit 121 
is arranged to cause a given current to flow to the light emitting element 
13. The received-light level storing circuit 123 is arranged to store the 
received light level output (A+B) in response to a signal from the CPU 120 
when the output (A-B) of the detecting circuit 122 becomes less than a 
prescribed level (i.e., a level obtained when a slit image is located in 
the middle part of the light receiving element 14). The determination 
circuit 124 is arranged to compare the output (A+B) of the detecting 
circuit 122 with the level stored by the received-light level storing 
circuit 123 and to supply an output to the electromagnet driving circuit 
57 when the current output (A+B) is lower than the stored level by a given 
value. 
The fifth embodiment differs from the fourth embodiment shown in FIG. 11 in 
that the data input to the determination circuit 124 is obtained from a 
circuit which is related to the light receiving element. Meanwhile, the 
light emission intensity of the light emitting element 13 is arranged to 
be kept unvarying by the light emitting element driving circuit 57. The 
arrangement of the fifth embodiment is such that: With the compensating 
optical system 30 in a position near to the limit of its compensatable 
range as shown in FIG. 13, when a part of the light flux coming from the 
mirror 5 to the light receiving element 14 is eclipsed by the edge of the 
aperture 29a of the mask 29 and, as a result, the total output (A+B) of 
the light receiving element 14 decreases, if the difference between the 
level of the output (A+B) and the level stored at the received-light level 
storing circuit 123 is less than the above-stated given value, the 
determination circuit 124 produces an output. The output then causes the 
current supply to the coil 11 to be increased by the electromagnet driving 
circuit 57. 
FIG. 15 is a flow chart showing the operation of the fifth embodiment. 
Since the flow of operation is about the same as in the case of the fourth 
embodiment shown in FIG. 12, the description of the flow is omitted. 
FIG. 16 shows the electrical arrangement of an image shake compensating 
device which is arranged as a sixth embodiment of the invention. FIG. 17 
is a flow chart showing the control operation to be carried out by the 
arrangement of FIG. 16. In FIG. 16, circuit elements indicated by the same 
reference numerals are arranged in the same manner as the corresponding 
elements of FIG. 11 and, therefore, the details of them are omitted from 
the following description: 
In the case of the sixth embodiment, the input to the determination circuit 
131 is arranged to be the output (A-B) of the detecting circuit 152. 
Further, unlike the fourth and fifth embodiments (FIGS. 11 and 14), the 
determination circuit 131 is arranged such that: A reference signal which 
is to be compared with the output (A-B) of the detecting circuit 152 is 
set by a reference level setting device 132 which has no relation to the 
light emitting and receiving elements. 
The fourth and fifth embodiment are arranged to control the compensating 
optical system and the light receiving element in such a way as to have 
the light flux which is generated by the light emitting element 13 fall on 
the middle part of the light receiving element 14, that is, to make the 
output .vertline.A-B.vertline. of the detection circuit 152 zero. In 
actuality, however, a delay in the control system tends to require an 
excessively long period of time before completion of the control operation 
for .vertline.A-B.vertline.=0. To solve this problem, the control system 
is preferably arranged to control the movements of the compensating 
optical system and the light receiving element in such a way as to obtain 
a state of .vertline.A-B.vertline.=.alpha.. The feedback gain of the 
control system is set in such a way as to have the value .alpha. within 
the allowable value range of the image shake on the image forming plane. 
The control operation can be speeded up by such arrangement. 
The sixth embodiment is arranged on the above-stated concept. The reference 
level to be set by the reference level setting device 132 as a reference 
signal for the determination circuit 131 is at the above-stated value 
.alpha.. Further, another reference level which is set by a reference 
level setting device 62 as a reference signal for the received-light level 
detecting circuit 61 is set irrelatively to the value .alpha.. 
In the normal operation of the sixth embodiment, the output 
.vertline.A-B.vertline. of the detecting circuit 152 never comes to exceed 
the value .alpha.. However, in case that the compensating optical system 
30 is driven to move to the limit point of the compensatable range thereof 
as shown in FIG. 13, the output .vertline.A-B.vertline. exceeds the value 
.alpha.. In that instance, the determination circuit 131 comes to produce 
an output to cause the electromagnet driving circuit 57 to increase the 
current supply to the coil 11 of the electromagnet. Further, as apparent 
from FIG. 17 which shows the control operation of the sixth embodiment, 
the control operation of the sixth embodiment closely resembles those of 
the fourth and fifth embodiments and is, therefore, omitted from 
description. 
Next, a seventh embodiment of the invention is described below with 
reference to FIGS. 18, 19 and 20: 
In these figures, the parts arranged in the same manner as those of the 
first embodiment are indicated by the same reference numerals and are 
described in a simplified manner to avoid duplicated description. In 
addition to the functions of floating body positioning arrangement of the 
first embodiment described in the foregoing, the floating body positioning 
arrangement of the seventh embodiment is arranged such that, when the 
compensating optical system is driven with a shake of the optical 
instrument detected by the detector 31 or 32, the speed at which the 
floating body is moved in the direction of decreasing the output of the 
detector is changed according to the amount of the output of the detector. 
The speed is changed in such a way as to cause the speed of the 
compensating optical system to be adjusted according to its position 
within the compensable range. 
To give the above-stated additional function to the floating body 
positioning arrangement, means for changing the amount of power supply to 
the above-stated coil 11 is included in the electrical control arrangement 
as will be described later: 
Meanwhile, the mask 29 which is disposed in front of the light receiving 
element 14 is provided with a triangular aperture 29b as shown in FIG. 18. 
The aperture 29b of the mask 29 is provided for the purpose of adjusting 
the amount of the output of each of the detectors 31 and 32 to each 
position of the compensating optical system within the compensatable 
range. The width of the aperture 29b corresponds to the compensatable 
range of the compensating optical system. The quantity of light incident 
upon the light receiving element 14 varies according to the position at 
which the light incident on the light receiving element passes through the 
aperture 29b. The amount of the output of the light receiving element 14 
varies accordingly. In the case of the mask 29 shown in FIG. 18, a point 
of the aperture 29b having the largest vertical dimension of the aperture 
corresponds to one of the limit points of the compensatable action range 
of the compensating optical system. Another point at which the vertical 
dimension is zero corresponds to the other limit points of the 
compensatable range. Therefore, when the light flux coming from the mirror 
5 to the mask 29 falls on a position where it is blocked from passing 
through the aperture 29b, the light receiving element produces no output. 
In this instance, the shake of the optical instrument is not compensatable 
by the compensating optical system. 
The circuit arrangement of this (the seventh) embodiment as a whole is the 
same as FIG. 11 which has been described in the foregoing. 
FIG. 19 shows by way of example the arrangement of the light emitting 
element driving circuit 158, the emitted-light level detecting circuit 63, 
the determination circuit 64 for determining the state of the detector and 
the emitted-light level storing circuit 65 of the image shake compensating 
device of the seventh embodiment. However, the image shake compensating 
device is not limited to the circuit arrangement of FIG. 19. 
Referring to FIG. 19, a transistor 601 is arranged to drive the light 
emitting element 13 (iRED). A transistor 602 is arranged to permit or 
prohibit the light emission of the light emitting element in response to a 
control signal 1 output from the CPU 156. A current detecting resistor 603 
is arranged to detect a light emission current equivalent to the amount of 
light emission by the light emitting element 13. A resistor 604 and a 
capacitor 605 jointly form a filter arranged to ensure increased safety in 
controlling the current of the light emitting element 13 to be constant. 
An operational amplifier 606 is arranged to constantly drive a current 
corresponding to the output (A+B) of the light emitting element 13. These 
elements jointly form the light emitting element driving circuit 158 
including the received-light level detecting circuit 61. A reference 
numeral 607 denotes an operational amplifier. A buffer 608 is arranged to 
turn on and off an analog switch 618 according to a control signal "m" 
output from the CPU 156. A buffer 609 is arranged to allow a 
sample-and-holding (storing) capacitor 610 to store an input to the 
operational amplifier 607 obtained while the analog switch 618 is on. 
These elements jointly form a storing circuit which is arranged to store 
the value of the light emitting element current obtained during a given 
period of time. 
An operational amplifier 611 is connected to the light emitting element 
current detecting resistor 603 and is arranged to produce a voltage value 
corresponding to the light emitting element current. The amplifier 611 
forms the emitted-light level detecting circuit 63. 
An operational amplifier 616 forms a subtraction circuit in conjunction 
with resistors 612 to 615. The subtraction circuit is arranged to produce 
a difference between the signal output from the emitted-light level 
storing circuit 65 and the signal output from the emitted-light level 
detecting circuit 63. An A/D converter 617 is arranged to convert an 
analog value into a digital value when the output of the subtraction 
circuit is sent to the CPU. These circuit elements 612 to 617 jointly form 
the determination circuit 64 mentioned in the foregoing. 
FIG. 20 is a flow chart showing a program to be executed by the CPU 156 of 
FIG. 11. In the image shake compensating device of the seventh embodiment, 
the mechanical arrangement is identical with the arrangement of the first 
embodiment. Therefore, the following describes the operation of the image 
shake compensating device of the seventh embodiment with reference to 
FIGS. 1 to 3, 6, 11 and 18 to 20: 
Referring to FIG. 11, when the switch 60 is closed, the CPU 156 causes a 
timer incorporated therein to operate as shown in FIG. 20. Following this, 
the electromagnet driving circuit 57 which is interlocked with the timer 
is caused to operate. As a result, a current is supplied to the coil 11 of 
each of the electromagnets disposed within the detectors 31 and 32. The 
power supply to the coil 11 continues until the operation of the timer 
comes to an end. With the coil 11 thus energized, the yokes 8 and 9 are 
magnetized. The vane part of the floating body 4 is moved to a position 
where it is aligned with the fore ends of the yokes 8 and 9 as shown in 
FIG. 2. The detectors 31 and 32 is reset by this. At that moment, if the 
optical instrument has not been swung on its horizontal or vertical axis, 
the light emitting and receiving elements 13 and 14, the mirror 5 and the 
variable angle prism device within each of the detectors 31 and 32 are in 
their postures as shown in FIG. 6(a). 
After the detectors 31 and 32 are reset, the CPU 156 causes the light 
emitting element driving circuit 158 to drive the light emitting element 
13 to emit light. If the optical instrument has not been shaken at that 
time, the compensating optical system is not driven as the light emitting 
and receiving elements 13 and 14 and the mirror 5 are in the positional 
relation as shown in FIG. 6(a). Before describing the operation to be 
performed when the optical instrument is shaken, the functions and actions 
of the circuit elements related to the light emitting and receiving 
elements 13 and 14 are described as follows with reference to FIG. 19: 
When the light flux emitted from the light emitting element 13 comes to the 
light receiving element 14, output voltages A and B are generated at the 
two ends of the light receiving element 14. A detection signal (A+B) is 
thus output from the light receiving element 14. The operational amplifier 
606 compares the signal (A+B) with the reference voltage KVC. If the 
signal (A+B) is found to be smaller than the reference voltage KVC, the 
transistor 601 is operated to increase the light emitting element current. 
This increases the quantity of light emitted from the light emitting 
element 13. The quantity of light received by the light receiving element 
14 also increases. The current for the light emitting element 13 increases 
until the signal (A+B) becomes equal to the reference voltage KVC. The 
light emitting element driving circuit 158 performs the above-stated 
action when a control signal l output from the CPU 156 is at a low level. 
The above-stated action is prohibited when the control signal l is at a 
high level. When this circuit 156 is in action, the signal (A+B) which 
indicates the total quantity of light received by the light receiving 
element 14 automatically becomes constant irrespective of the states of 
the detectors 31 and 32. 
While the image shake compensating device is in the initial state as shown 
in FIG. 6(a), the relative positions of the light emitting and receiving 
elements 13 and 14 and the mirror 5 within each of the detectors are 
unconditionally determined. Then, a voltage corresponding to the current 
for the light emitting element 13 flowing under this condition is detected 
by a current detecting resistor 603. The detected voltage is sampled by 
the emitted-light level storing circuit 65. The voltage value is 
accumulated at the sample-and-hold capacitor 610. After that, the voltage 
value of the capacitor 610 is retained. In other words, a current value 
obtained in the initial state is stored. 
The output (A-B) of the detecting circuit 152 becomes zero when the light 
flux emitted by the light emitting element 13 comes to the middle part of 
the light receiving element 14 (the center of the compensatable range of 
the compensating optical system). Therefore, while the image shake 
compensating device is in its initial state as shown in FIG. 6(a), the 
output (A-B) which is one of the outputs of the detecting circuit 152 is 
zero. Therefore, the driving circuit 53 for the compensating optical 
system driving actuator is kept in an inoperative state. 
When the optical instrument is shaken, or turned round, on its horizontal 
or vertical axis, the tubular member 2 of the detector 31 or 32 is turned 
round on the axis of the floating body 4 together with the optical 
instrument. However, the floating body 4 is kept in its original position 
by the force of inertia of the liquid in the tubular member 2. As a 
result, a change occurs in the positional relationship between the light 
emitting element 13 and the mirror 5. The incident position of the light 
flux coming from the mirror 5 to the light receiving element 14 also 
changes. 
FIG. 6(b) shows the condition described above. The optical instrument is in 
a state of having been turned round on its vertical axis, which is 
parallel to the pin 19a. Accordingly, the image forming lens 40 and the 
image forming plane 41 also slant. An image formed on the image forming 
plane 41 also moves from its initial image forming position P to another 
position Q to show an image shake. In this instance, the positions of the 
light receiving element 14 and the mirror 5 relative to each other also 
change. Meanwhile, the passing position of the light flux emitted from the 
light emitting element 13 and passing through the aperture 29b of the mask 
29 also changes. This causes a change in the quantity of light incident on 
the light receiving element 14. As a result, the output (A-B) which is one 
of the outputs of the detecting circuit 152 is no longer zero. The other 
output (A+B) of the circuit 152 also changes. This causes a change in an 
input to the received light level detecting circuit 61. If this input is 
higher than the reference level KVC, the received-light level detecting 
circuit 61 produces an output for the light emitting element driving 
circuit 158. The driving current for the light emitting element 13 is 
either increased or decreased by this. When the emitted-light level 
detecting circuit 63 detects the light emitting element driving current 
thus obtained, a detected value thus is supplied to the determination 
circuit 64. The determination circuit 64 compares the current detected 
value of the light emitting element current with the stored value of the 
current obtained under the initial condition mentioned above. Through this 
comparison, the determination circuit 64 determines the current state of 
the detector, i.e., the positional relationship currently obtained among 
the light receiving and emitting elements 14 and 13 and the mirror 5, and 
that of the compensating optical system, i.e., the variable angle prism 
device. The operational amplifier 616 which is included in the 
determination circuit 64 produces from its output terminal an output as a 
result of comparison of the output voltage of the emitted-light level 
detecting circuit 63 and the terminal voltage of the capacitor 610 of the 
emitted-light level storing circuit 56. The output is converted into a 
digital value by the A/D converter 617. The digital value thus obtained is 
applied to the electromagnet driving circuit 57 in accordance with a 
control signal "n" output from the CPU 156. 
Further, the electromagnet driving circuit 57 is arranged to operate under 
the control of the control signal applied thereto from the CUP 156. When 
the control signal is applied from the CPU 156, the circuit 57 is driven 
according to the amount of the input signal obtained from the 
determination circuit 64. 
Meanwhile, since the other output (A-B) of the detecting circuit 152 (FIG. 
11) is not zero under the condition as shown in FIG. 6(b), the output 
(A-B) of the detecting circuit 152 is supplied to the actuator driving 
circuit 53. A current corresponding to the output (A-B) then flows to the 
coil 23 of the actuator 33. With the coil 23 of the actuator 33 thus 
energized, the shaft 33a of the actuator 33 is moved forward as viewed on 
FIG. 2. The front frame 19 of the variable angle prism is turned round 
clockwise on the pin 19a (counterclockwise on the pin 19a as viewed on 
FIG. 6(b)). Therefore, the light receiving element 14 of the detector 32 
which is carried by the front frame 19 also turns round counterclockwise 
on the pin 19a from its position of FIG. 6(b). When the front frame 19 is 
turned round until the reflection light from the mirror 5 which is secured 
to the floating body 4 comes to fall on the light receiving element 14 in 
the same incident state as its incident state obtained before the front 
frame 19 began to be turned round, the output (A-B) of the detecting 
circuit 152 (FIG. 11) becomes zero. The action of the actuator driving 
circuit 53 then comes to a stop. The power supply to the coil 23 of the 
actuator 33 also comes to a stop to bring the turning movement of the 
front frame 19 to a stop. 
FIG. 6(c) shows the variable angle prism and the detector 32 as in their 
states obtained when the front frame 19 is turned round until the 
reflection light from the mirror 5 comes to the light receiving element 14 
in the same incident state as before the commencement of the turning 
movement of the front frame 19. Under this condition, the pencils of rays 
"a", "b" and "c" incident on the variable angle prism form an image in the 
focal point position P of the image forming lens 40. This means that the 
image has been compensated for the image shake. 
In order to enable the image shake compensating device to adequately cope 
with the conditions (a) and (b) described for the fourth embodiment in the 
foregoing, the seventh embodiment is arranged to control the speed of the 
compensating optical system when the compensating optical system is close 
to the limit of the compensatable range. For example, when the variable 
angle prism is moved near to the limit point (the left maximum inclination 
angle of the front frame 19) as shown in FIG. 13, the electromagnet 
driving circuit 57 increases the amount of power supply to the 
electromagnet 11 in accordance with the absolute value of the output of 
the determination circuit 64. This increases a magnetic urging force on 
the floating body 4. Therefore, the compensating speed of the compensating 
optical system can be lowered accordingly as the compensating optical 
system comes closer to the limit point of the compensatable range. Then, 
at the end of the compensatable range, the compensating optical system can 
be brought to a stop from the slowed-down speed. This arrangement 
effectively prevents the occurrence of a sudden large image shake at a 
certain point of time even in the case of the condition (a). 
Further, when the compensating optical system is in one of the limit 
positions of the compensatable range as shown in FIG. 13, the 
determination circuit 64 and the electromagnet driving circuit 57 act in 
the above-stated manner to slowly bring the floating body 4 back to its 
initial position as shown in FIG. 2. The compensating optical system is 
thus readied for its normal compensating action. This arrangement ensures 
image shake compensation also under the condition (b). 
The mask 29 which is disposed within each of the detectors 31 and 32 is 
provided with an aperture 29b having a lateral width corresponding to the 
compensatable range of the compensating optical system. The vertical 
dimension of the aperture 29b linearly varies from one end to the other. 
The quantity of light passing through the aperture 29b varies according to 
its incident position relative to the aperture 29b. Therefore, the output 
of the light receiving element 14 indicates the position of the 
compensating optical system as well as the positional relation between the 
light emitting and receiving elements of the detector. In the case of the 
seventh embodiment, therefore, the position of the compensating optical 
system as to whether the system is near the middle point or the limit 
point of its compensatable range, etc., is determined according to a 
change in the output of the light emitting element or the output of the 
light receiving element. The compensating optical system is controlled in 
the above-stated manner on the basis of the result of determination. The 
seventh embodiment is therefore capable of making image shake compensation 
even when complex vibrations are inflicted on the optical instrument. 
FIGS. 21 and 22 show the electrical arrangement and the control program 
flow of an eighth embodiment of the invention. The mechanical arrangement 
of the image shake compensating device of the eighth embodiment is 
identical with that of the first embodiment and is therefore omitted from 
the illustration. Further, the overall circuit arrangement of the eighth 
embodiment is the same as that of the FIG. 14. 
FIG. 21 is a circuit diagram showing by way of example the arrangement of 
the detecting circuit 122, the received-light level storing circuit 123 
and the determination circuit 124 which detects and determines the states 
of the detector and the compensating optical system. Further, among the 
circuits shown in FIG. 21, the received-light level storing circuit 123 
and the determination circuit 124 are arranged in the same manner as the 
received-light level storing circuit 65 and the determination circuit 64 
shown in FIG. 19 respectively. 
Referring to FIG. 21, an operational amplifier 703 forms a 
current-to-voltage converter in conjunction with resistors 701 and 702. 
Another operational amplifier 706 also forms a current-to-voltage 
converter in conjunction with resistors 704 and 705. The 
current-to-voltage converter which includes the operational amplifier 703 
is arranged to produce a voltage VA corresponding to a current output from 
one element 14a of the light receiving element 14. The current-to-voltage 
converter which includes the operational amplifier 706 is arranged to 
produce a voltage VB corresponding to a current output from the other 
element 14b of the light receiving element 14. These voltages VA and VB 
are supplied to a subtracter which is composed of resistors 707 to 710 and 
an operational amplifier 711. The subtracter produces an output (A-B) 
which represents a difference between the inputs VA and VB. The voltages 
VA and VB are also supplied to an adder which is composed of resistors 713 
to 716 and an operational amplifier 717. The adder produces an output 
(A+B) which represents a sum of the inputs VA and VB. 
An A/D converter 712 is arranged to generate outputs which are obtained by 
converting the output (A-B) of the subtracter and the output (A+B) of the 
adder into digital values. A buffer (voltage follower) 723 is formed by an 
operational amplifier. An operational amplifier 718 is arranged to produce 
a difference between the terminal voltage (a stored value) of a storage 
capacitor 722 and the output voltage of the above-stated adder. A buffer 
719 is arranged to receive a control signal "m" from the CPU 120. An 
analog switch 720 is arranged to turn on when the buffer 719 produces an 
output. A buffer 721 is arranged to receive the output signal of the 
operational amplifier 718. Resistors 724 to 727 are arranged to form a 
subtracter in conjunction with an operational amplifier 728. This 
subtracter is arranged to produce an output representing a difference 
between the output of the received-light level storing circuit 123 and the 
output (A+B) of the buffer 723. An A/D converter 729 is arranged to apply 
a signal output to the electromagnet driving circuit 57 (FIG. 16) upon 
receipt of a control signal "n" from the CPU 120. 
The eighth embodiment differs from the seventh embodiment in the following 
points: The actuator driving circuit 53 is driven by a signal of a value 
(A-B)/(A+B); and the position of the compensating optical system is 
determined according to the output of the light receiving element. 
Further, the operation of circuits and the mechanical operation of the 
image shake compensating device are almost the same as those of the 
seventh embodiment and are, therefore, omitted from description. 
FIG. 23 shows an example of modification of the mask included in each of 
the detectors 31 and 32 of the seventh embodiment. In this case, a mask 
429 is provided with no aperture nor slit. As shown in FIG. 23, the mask 
which has no hole is arranged to have its light transmission factor vary 
in the lateral direction, i.e., in the direction of the detecting action. 
The lateral length of the light transmitting part of the mask 429 
corresponds to the compensatable range of the compensating optical system. 
The light flux incident on this light transmitting part causes the light 
receiving element 14 to produce its output corresponding to the position 
of the compensating optical system within the compensatable range. This 
mask can be elaborately manufactured in accordance with known printing 
technology, etc. so that the detecting accuracy of the embodiment can be 
enhanced. Another advantage of the mask lies in that a detection signal 
can be easily generated in the form of a digital signal instead of an 
analog signal. 
In each of the fourth to eighth embodiments described in the foregoing, the 
detectors 31 and 32 are arranged as optical detector, each including the 
light emitting and receiving elements. However, the detector of course can 
be differently arranged without including the light emitting and receiving 
elements. In the embodiments, the speed and position of the compensating 
optical system are arranged to be controlled by changing the magnetic 
field for the floating body within the detector when the compensating 
optical system is near to the limit point of the compensatable range. This 
arrangement may be changed to directly control the actuator. 
Further, the output of the determination circuit which determines the state 
of the compensating optical system may be arranged to be supplied to some 
suitable display device to allow the operator of the optical instrument to 
know the state of the compensating optical system. Further, the 
above-stated optical mask may be replaced with a magnetic mask or the 
like. 
In each of the embodiments described, the image shake compensating device 
is arranged to use the hydrostatic sensors as detectors. However, it will 
be apparent to those skilled in the art that detectors of different kinds 
may be used in place of the hydrostatic sensors without departing from the 
scope and spirit of the invention. 
In the above-stated embodiments, the operation of the electromagnet driving 
circuit 57 for resetting the detectors 31 and 32 in response to the 
turning-on operation of the start switch 60 is stopped when the counting 
operation of the timer comes to an end. However, the electromagnet driving 
circuit 57 may continue operating without alteration or with its acting 
force weakened even after the counting operation of the timer comes to an 
end. In this case, the operation of the electromagnet driving circuit 57 
for returning the compensating optical system from the compensatable limit 
position to the initial position as described in the above embodiments 
needs to be continued with the acting force of the electromagnet driving 
circuit 57 strengthened.