Abstract:
An image stabilizing device includes a vibration detector for detecting a vibrated state of an image, a vibration compensator responsive to the vibration detector to compensate for the vibrated state of the image, connection circuitry for substantially connecting the vibration detector to the vibration compensator and alleviating circuitry for preventing the vibration compensator from effecting sudden starting of an operation responding to the vibration detector during the connection by the connecting circuitry.

Description:
This is a continuation application under 37 CFR 1.62 of prior application Ser. No. 08/159,934, filed Nov. 30, 1993 ABN, which is a continuation of Ser. No. 08/029,927, filed Mar. 11, 1993, which is a continuation of Ser. No. 07/700,793, filed May 15, 1991, all now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an image stabilizing device for preventing the image blur of an optical instrument such as a camera resulting from hand vibration. 
     2. Related Background Art 
     In recent optical instruments such as cameras, almost all of functions necessary for photographing such as the determination of exposure and focusing are automatized and failure attributable to the photographing function has become very rare, and recently, the development of cameras in which failure in photographing attributable to any other factor than the photographing function, for example, the blur of a photographed image caused by vibration such as hand vibration, is automatically suppressed has been put forward. 
     Usually, to prevent vibration from occurring to a photographed image even if hand vibration occurs with the release of a camera shutter, it is necessary that means capable of detecting the vibration of the camera and properly accomplishing the correction of image blur on the basis of the detected information, i.e., an image stabilizing device, be carried on the camera. 
     FIG. 18 of the accompanying drawings shows in schematic block diagram an example of an image stabilizing device according to the prior art. First describing the vibration detecting means, this is constructed as optical angle deviation detecting means. That is, a case  701  enclosing therein liquid whose viscosity or the like is suitably selected and provided so as to move with a camera (or a lens barrel) has therein a mechanism supporting a float  702  freely rotatable about a rotary shaft  703 , and assuming, for example, that vibration has occurred to the camera (lens barrel) and this camera has rotated by θ in  in relative to the coordinates system of absolute space, the case  701  moves with the camera. In contrast, the liquid in the case maintains its stationary state relative to the absolute space by its inertia force. Thus, the float  702  and the case  701  have rotated by θ in  in corresponding to said vibration. 
     So, by light from a light emitting element  706  fixedly provided on the camera (lens barrel) being reflected by the float  702  and the reflected light being received by a light receiving element  705 , the angle deviation of said vibration can be detected in a position detecting circuit  704  connected to the light receiving element  705 . 
     On the other hand, description will now be made of a mechanism for making an image on the image plane apparently stationary. In the example of the prior art shown in FIG. 18, liquid having a predetermined refractive index is enclosed in an accordion-shaped container formed by connecting two transparent plates together by bellows, thereby constituting a variable vertical angle prism  707 , which is used as optic axis eccentricity means. The transparent plate on the object side is suitably tilted relative to the fixed transparent plate adjacent to a photo-taking lens  708  by an actuator  713  which is a solenoid so that the photographing optic axis can be changed. That is, by the transparent plate on the object side of the variable vertical angle prism  707  rotating by θ out , a photographing optical path passing through the photo-taking lens  708  to the surface  709  of film rotates relative to the optic axis in proportion to said Gout and in accordance with a proportion constant determined by the refractive index of the enclosed liquid. 
     As described above, in the camera of FIG. 18, vibration occurring to the camera is detected by the optical angle deviation detecting means using the rotatable float  702  and the vertical angle of the variable vertical angle prism  707  is varied by an angle corresponding to the detected vibration, whereby even when the camera vibrates, the incident light from an object can always be directed to the same position on the surface  709  of the film, thereby suppressing the blur of a photographed image. 
     In the prior-art device of FIG. 18, the actual state of the angle deviation θ out  effected by the variable vertical angle prism  707  is detected by a position detecting circuit  712  disposed near the variable vertical angle prism  707 , and an amount of output indicative of said angle deviation θ out  is subtracted from a signal indicative of the angle θ in  which is the output of the position detecting circuit  704  detected as the vibration of the camera, and said subtracted output is amplified by an amplifier circuit  714  and thereafter is input to a driver circuit  716  through a phase compensator circuit  715 . 
     Accordingly, the driving of the actuator  713  is feedback-controlled thereby and accurate image stabilization control is realized. 
     Now, in the image stabilizing device described above with reference to FIG. 18, the starting or termination of the image stabilizing operation are effected, for example, by the ON/OFF of a manually operated switch extraneously operated which is designated by  720  in FIG. 18, and this forms means for actually starting or terminating the operation. 
     That is, the input from the angle deviation detecting means to the actuator  713  is effected by the ON/OFF of the manually operated switch  720 . 
     In such a construction, when the switch  720  is closed when inputting the detection output from the above-described optical angle deviation detecting means to the driver  716  of the variable vertical angle prism (that is, starting the image stabilization), the signal indicative of the vibrated state which is detected by the angle deviation detecting means is intactly input to the driver  716 . 
     However, such control, although not said to be unsuitable as a device which satisfies the image stabilizing function, has led to the problem that it results in a system inconvenient for use when viewed from the viewpoint of the use of the camera carrying such device thereon. 
     Considering, for example, a case where the switch  720  is closed with the position detection signal from the angle deviation detecting means being greatly off the usual central position and image stabilization control is started, the transparent plate on the object side of the variable vertical angle prism  707  is suddenly displaced from its inclined state to its parallel state. 
     This results in a sudden change in the optical path, and in a camera of a type such as TTL in which an object is seen through a viewfinder and a photo-taking optical system, there occurs the discontinuity (so-called skip) of the viewfinder image, and this has led to the disadvantage of giving the photographer a great feeling of physical disorder. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of the above-noted circumstances and intends to provide an image stabilizing device which is provided with vibration detecting means for detecting the vibrated state of an image, vibration compensating means responsive to said vibration detecting means to compensate for the vibration of the image, connecting means for substantially connecting said vibration detecting means to said vibration compensating means, and alleviating means for preventing said vibration compensating means from effecting sudden starting of an operation responding to said vibration detecting means during said connection by said connecting means and which eliminates the above-noted problem peculiar to the prior-art image stabilizing device and also eliminates the discontinuity of a viewfinder image or the like and does not give the user a reeling of physical disorder. 
     Other objects of the present invention will become apparent from the following detailed description of some specific embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram showing the construction of an image stabilizing device according to an embodiment of the present invention. 
     FIG. 2 is a flow chart showing the operation of the CPU  100  of FIG.  1 . 
     FIG. 3 is a block diagram showing the construction of an image stabilizing device according to another embodiment of the present invention. 
     FIG. 4 is a flow chart showing the operation of the CPU  100  of FIG.  3 . 
     FIG. 5 is a block diagram showing the construction of an image stabilizing device according to still another embodiment of the present invention. 
     FIG. 6 is a flow chart showing the operation of the CPU  100  of FIG.  5 . 
     FIG. 7 is a block diagram schematically showing the construction of an image stabilizing device according to yet still another embodiment of the present invention. 
     FIGS. 8A and 8B is a circuit diagram showing the specific construction of FIG.  7 . 
     FIGS. 9A,  9 B and  9 C are circuit diagrams analogously showing the operation of the CPU  100  of FIG.  8 . 
     FIGS. 10 to  13 B are flow charts showing the operation of the CPU  100  of FIG.  8 . 
     FIGS. 14 to  15 B are flow charts showing another embodiment of the operation of the CPU  100  of FIG.  8 . 
     FIGS. 16,  17 A, and  17 B are flow charts showing still another embodiment of the operation of the CPU  100  of FIG.  8 . 
     FIG. 18 is a block diagram for illustrating an image stabilizing device according to the prior art. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Some embodiments of the present invention will hereinafter be described with reference to the drawings. 
     In FIGS. 1 to  17 , common elements are given identical reference numerals for convenience and some of them will not be described in detail. Also, in the description of the flow charts of FIGS. 2,  4 ,  6  and  10  to  17 , the numbers are indicative of the numbers of the steps of procedure. 
     FIG. 1 is a block diagram showing the construction of an image stabilizing device according to an embodiment of the present invention. 
     The device according to the present embodiment is one in which the starting and termination of the image stabilizing operation are extraneously operated by a manually operated switch. 
     In FIG. 1, angle deviation detecting means for detecting vibration such as hand vibration comprises a cylindrical case  2  filled with liquid  3  having a predetermined refractive index, and a float  4  of a magnetic material rotatable about a predetermined rotary shaft and provided in the liquid. The float  4  is adapted to be held in a predetermined position by a closed magnetic circuit formed by a permanent magnet  1  provided so as to surround the case  2  when there is no vibration. 
     When vibration occurs to a lens barrel and the float  4  rotates relative to the case  2  as described above, the amount of this rotation is detected by optical detecting means which moves with the lens barrel. 
     That is, signal light emitted from a light emitting element (e.g. an infrared light emitting diode IRED)  6  is reflected by the surface of the float  4  and enters a light receiving element for position detection (e.g. a semiconductor position detecting element PSD)  5  and therefore, the position of incidence of the signal light onto the light receiving element  5  is changed by said relative rotation with a result that the output currents Ia and Ib of the light receiving element  5  vary. 
     The output currents Ia and Ib are amplified by a current-voltage converting circuit comprised of an operational amplifier  10 , a resistor  11  and a capacitor  12  and a current-voltage converting circuit comprised of an operational amplifier  13 , a resistor  14  and a capacitor  15 , and the respective outputs thereof are input to an addition circuit comprised of an operational amplifier  21  and resistors  22 ,  23 ,  24  and  25  and a subtraction circuit comprised of an operational amplifier  16  and resistors  17 ,  18 ,  19  and  20 . 
     The output of the addition circuit is input to an IRED driver circuit comprised of an operational amplifier  26 , resistors  27 ,  28 ,  31 , a capacitor  29  and a transistor  30 , and is feedback-controlled so that as a whole, the output of the addition circuit may be equal to a reference voltage KVC. 
     On the other hand, the amount of displacement of a variable vertical angle prism  41 , as in the above-described angle deviation detecting means, is detected by a light receiving element  43  and a light emitting element  44 , and photocurrents Ic and Id produced from the light receiving element  43  are amplified by a current-voltage converting circuit comprised of an operational amplifier  50 , a resistor  51  and a capacitor  52  and a current-voltage converting circuit comprised of an operational amplifier  53 , a resistor  54  and a capacitor  55 , and are input to a subtraction circuit comprised of an operational amplifier  56  and resistors  57 ,  58 ,  59  and  60  and an addition circuit comprised of an operational amplifier  61  and resistors  62 ,  63 ,  64  and  65 , respectively. The output of this addition circuit is input to an IRED driver circuit comprised of an operational amplifier  66 , resistors  67 ,  68 ,  71 , a capacitor  69  and a transistor  70  and therefore, the output of the addition circuit is always equal to the reference potential KVC. 
     The outputs of the operational amplifiers  16  and  56  obtained in the manner described above are of values corresponding to the amount of angle deviation relative to absolute space and the amount of vertical angle deviation of the variable vertical angle prism  41 . The output of the operational amplifier  16  is connected to a resistor  83  through an analog switch  80  connected to an inverter  82 , the output of the operational amplifier  56  is connected to a resistor  84 , and both of these outputs are also connected to the inverting input terminal of an operational amplifier  85  to which a feedback resistor  86  is connected. 
     Also, an analog switch  81  is connected to the resistor  83  in parallel to the analog switch  80 , and one input thereof is connected to the ground, thereby constituting operation control means for effecting the ON and OFF of the angle deviation detecting means and a circuit including the variable vertical angle prism  41 . 
     The circuit comprised of the operational amplifier  85  and resistors  83 ,  84  and  86  is a circuit originally known as an addition circuit, but in the present embodiment, the polarity of the output representative of the movement of the variable vertical angle prism  41  is inverted relative to the output of the angle deviation detecting means and as a result, said circuit is a subtraction circuit which constitutes means for finding the amount of correction for the optic axis change of the present invention (in the present embodiment, the amount of driving of the deviation of the vertical angle of the variable vertical angle prism  41 ). 
     Next, the output of the operational amplifier  85  is input to a phase advance compensation circuit comprised of a capacitor  91  and resistors  92  and  93 , and is input to a buffer amplifier  90  after the phase compensation of the entire feedback system is effected. One output of this buffer amplifier is input to a power amplifying circuit comprised of an operational amplifier  97 . The other output is input to a power amplifying circuit of the inversion type comprised of an operational amplifier  94  and resistors  95  and  96 . 
     The outputs of these two power amplifying circuits are then input to a coil  98  which is an actuator for the variable vertical angle prism, and control for changing the vertical angle of the variable vertical angle prism  41  is effected by the operation of the coil  98 . In the present embodiment, the buffer amplifier  90 , the two power amplifying circuits and the coil together constitute optic axis changing means for changing (rotating) of the optic axis. 
     The outputs of a comparator  87  and a comparator  88  are connected to the input {overscore (HDIN)} to a CPU  100  through a NAND gate  89 . 
     A positive reference voltage Vc is connected to the non-inverting input terminal of the comparator  87  and a negative reference voltage −Vc is connected to the inverting input terminal of the comparator  88 , thereby constituting a so-called window comparator which compares the output of the operational amplifier  16  with the reference voltages and whose input {overscore (HDIN)} assumes an L level only when the output of the operational amplifier  16  falls within the range of Vc and −Vc. 
     Further, in the present embodiment, extraneously operated switches  107   a - 107   k  are connected through a switch interface  107  to the CPU  100  comprised of a microcomputer or the like so that the states of the switches  107   a - 107   k  may be transmitted to the CPU  100 . 
     By the construction as described above, the angle deviation driving of the variable vertical angle prism  41  corresponding to the relative angle deviation of the float  4  is effected even if the lens barrel is moved by hand vibration or the like, and thus the object image on the image plane of the camera can keep its stationary state. 
     The operations of the starting and termination of the image stabilizing operation in the present embodiment will now be described with reference to the flow chart of FIG. 2 which shows the operation of the CPU  100 . 
     First, the CPU  100  starts its initial operation by a power on reset circuit, not shown, and sets a port output {overscore (ISCONT)} to an H level. In this state, the output of the inverter  82  assumes an L level and therefore, the analog switch  80  becomes OFF and the analog switch  81  becomes ON, and the operation of the variable vertical angle prism  41  is isolated from the signal from the angle deviation detecting means and remains in a state stationary at the center position, and the image stabilizing operation is maintained in its OFF state. Also, in the initial operation, the value of the latch ISONL of the CPU  100  which memorizes the state of each switch is set to an L level (steps  200  and  201 ). 
     Subsequently, the state of this latch ISONL is judged (a step  202 ), and if the value of this latch is at an L level, advance is made to a step  203 , and if said value is at an H level, advance is made to a step  210 . 
     Steps  203 - 209  are the starting routine of the image stabilizing operation, and at the step  203 , the state of the extraneously operated switch  107 a (hereinafter referred to as ISSW) shown in FIG. 1 which indicates the starting and termination of the image stabilizing operation is read through the switch interface  107 . If ISSW is OFF, it is judged that the state of ISSW remains OFF and has not changed from the OFF state, and return is made to the step  202 , but if ISSW is ON, it is judged that the state of ISSW has changed from OFF to ON, and advance is made to the step  204 , where the control for starting the image stabilizing operation is started. 
     At the step  204 , a timer  101  contained in the CPU  100  is started, and subsequently at the step  205 , the state of the input {overscore (HDIN)} is judged. 
     As long as the output of the angle deviation detecting means is greater than the reference voltage Vc or smaller than the reference voltage −Vc, the output of the window comparator, i.e., the signal of the input {overscore (HDIN)} to the CPU  100 , is at an H level and at this time, advance is made to the step  206 , and when said output has come into between the reference voltages Vc and −Vc, the signal of the input {overscore (HDIN)} assumes an L level, and at this time, advance is made to the step  207 . 
     At the step  206 , whether the timer  101  has reached a predetermined time T E  is judged, and if it has not reached T E , return is made to the step  205 , and if it has reached T E , it means that within a set time, said output has never fallen within the range of the reference voltages Vc and −Vc, but if the judging operation is continued any further, the time lag of the starting of the image stabilizing operation will become too long and therefore, the judging operation is terminated and advance is made to the step  207 . 
     At the step  207 , the port output {overscore (ISCONT)} is set to an L level, whereby the analog switch  81  becomes OFF and the analog switch  80  becomes ON, and the output of the angle deviation detecting means is connected to the coil  98 , and the image stabilizing operation is started. 
     Then, at the step  208 , the latch ISONL is set to an H level to thereby cause it to memorize the states of the switches, and at the step  209 , the timer is stopped and return is made to the step  202 . 
     Steps  210 - 216  are the termination routine of the image stabilizing operation. If at the step  202 , the latch ISONL is at an H level, advance is made to the step  210 , where the state of ISSW is judged. If ISSW is ON, return is made to the step  202 , but if ISSW is OFF, it is judged that ISSW has changed from ON to OFF, and advance is made to the step  211 , where the control for terminating the image stabilizing operation is started. 
     At the step  211 , the timer  101  is started and then, at the step  212 , the state of the input {overscore (HDIN)} is judged. 
     As in the case of the steps  205 - 206 , as long as the value of the operational amplifier  16  which is the output of the angle deviation detecting means is greater than the reference voltage Vc or smaller than the reference voltage −Vc, the signal of the input {overscore (HDIN)} is at an H level and at this time, advance is made to the step  213 , and when said output has fallen within the range of the reference voltges Vc and −Vc, the signal of the input {overscore (HDIN)} assumes an L level, and at this time, advance is made to the step  214 . 
     At the step  213 , whether the value of the timer  101  has reached  9  predetermined time T F  is judged, and if it has not reached T F , return is made to the step  212 , and if it has reached T F , the time lag of the termination of the image stabilizing operation will become too long if the judging operation is continued any further and therefore, the judging operation is terminated and advance is made to the step  214 . 
     At the step  214 , the port output {overscore (ISCONT)} is set to an H level and the analog switch  80  is rendered OFF and the analog switch  81  is rendered ON, whereby the output of the angle deviation detecting means is disconnected from the coil  98 , and the image stabilizing operation is terminated. 
     Subsequently, at the step  215 , the latch ISONL is set to an L level to thereby cause it to memorize the states of the switches, and at the step  216 , the timer  101  is stopped, whereafter return is made to the step  202 . 
     In the construction described above, the values of the reference voltages Vc and -Vc are set to values very approximate to the ground level and therefore, the amount of shift when the image stabilizing operation has changed from OFF to ON (the steps  203 - 209 ) is small and the detected hand vibration is usually a periodic signal and thus, the output of the angle deviation detecting means crosses the ground level at an interval of several seconds without fail and therefore, the continuous shift of the operation becomes possible even if there is lesser time delay. 
     This also holds true when the image stabilizing operation has changed from ON to OFF, and the image stabilizing operation is terminated at a point of time at which the output of the angle deviation detecting means has fallen within a predetermined range and therefore, discontinuity of the viewfinder image does not occur. 
     FIG. 3 is a block diagram showing the construction of an image stabilizing device according to another embodiment of the present invention. In the present embodiment, signalling from outside for starting and terminating the image stabilizing operation is effected on the basis of the zoom position of the photo-taking lens. 
     That is, the image vibration by a camera shake such as hand vibration is more apt to occur as the focal length of the photo-taking lens becomes longer and therefore, the present embodiment intends to automatically control the starting and termination of the image stabilizing operation depending on whether the focal length of the photo-taking lens is a focal length for which the image vibration is apt to occur. 
     The reference numerals  1 - 107  in FIG. 3 in designate elements identical to those in FIG. 1, and the reference numerals  110 - 118  denote constructions related to a zoom mechanism which is the characteristic construction of the present embodiment. 
     That is, in FIG. 3, the reference numeral  111  designates a variable resistor whose resistance value is set so as to be variable in conformity with the zoom position of the photo-taking lens, and a voltage set by the variable resistor  111  of a reference voltage KVC is input to an A/D converter  110 , and this provides an input to the CPU  100 . 
     Also, a bridge circuit constituted by transistors  112 ,  113 ,  115  and  117  constitutes a motor driver circuit for a motor  118  which actually governs the zooming of the photo-taking lens, and determines the direction of zooming by a control signal from the CPU  100 . 
     The operations of starting and terminating the image stabilizing operation in the present embodiment will now be described with reference to the flow chart of FIG. 4 which shows the operation of the CPU  100 . 
     In FIG. 4, steps  200 - 202  are the same as those in FIG. 2, and if the latch ISONL is at an L level, advance is made to a step  250 , and if the latch ISONL is at an H level, shift is made to a step  251 . 
     At the step  250 , the zoom position of the photo-taking lens is judged for the starting of the image stabilizing operation. 
     That is, assuming that by preset zooming control, the photo-taking lens has been moved from the WIDE side to the TELE side, if the zoom position f is smaller than a predetermined value D (which becomes greater toward the TELE side), return is made to the step  202 , but when the zoom position moves to the TELE side and the value of f becomes greater than D, advance is made to a step  204 . 
     The step  204  to step  209  are the starting routine of the image stabilizing operation, and as described in the previous embodiment, the image stabilizing operation is started at a point of time at which the output of the angle deviation detecting means has fallen within a predetermined level range. 
     At a step  251 , the zoom position of the photo-taking lens is judged for the termination of the image stabilizing operation. 
     That is, assuming that by preset zooming control, the photo-taking lens has been moved from the TELE side to the WIDE side, if the zoom position f is greater than the predetermined value D, return is made to the step  202 , but when the zoom position moves to the WIDE side and the value of f becomes smaller than D, advance is made to a step  211 . 
     The step  211  to step  216  are the termination routine of the image stabilizing operation, and as described in the previous embodiment, the image stabilizing operation is terminated at a point of time whereat the output of the angle deviation detecting means has fallen within a predetermined level range. 
     Accordingly, again in the present embodiment, as in the previous embodiment, discontinuity of the viewfinder image occurs during neither of the starting and termination of the image stabilizing operation. 
     FIG. 5 shows the construction of an image stabilizing device according to still another embodiment of the present invention. 
     The present embodiment is such that the image stabilizing operation is terminated when the source voltage has become a voltage inappropriate to perform the image stabilizing operation, as when the source voltage has been reduced by other loads such as the feeding of the film and the driving of the lens, and that the image stabilizing operation is started when this not the case. 
     The reference numerals  1 - 107  in FIG. 5 designate elements identical to those in FIG. 1, and the reference numerals  120 - 126  denote elements related to the construction of source voltage monitoring means which is the feature of the present embodiment. 
     In FIG. 5, a value obtained by dividing the source voltage Vcc by resistors  125  and  126  is input to the non-inverting input terminal of a comparator  120 , and a reference voltage Vc is connected to the non-inverting input terminal and the output {overscore (BCNG)} of the comparator  120  is input to the CPU  100 . 
     Also, a constant current circuit constituted by an operational amplifier  121  and a resistor  123  supplies a constant current to a coil  122  for the feeding of the film, the driving of the lens, etc., and the ON/OFF control of the operational amplifier  121  is effected by the output {overscore (CLON)} of the CPU  100  through a transistor  124 . 
     The operations of starting and terminating the image stabilizing operation in the present embodiment will now be described with reference to the flow chart of FIG. 6 which shows the operation of the CPU  100 . 
     In FIG. 6, steps  200 - 202  are the same as those in FIG.  2  and form the starting routine of the image stabilizing operation. If the latch ISONL is at an L level, advance is made to a step  260 , and if the latch ISONL is at an H level, shift is made to a step  261 . 
     At the step  260 , whether the source voltage Vcc is greater than a predetermined level Vc is judged. 
     If the output {overscore (CLON)} of the CPU  100  is at an L level in advance and with the coil  122  energized, the value of the source voltage Vcc is smaller than the predetermined level Vc, return is made to the step  202 , but if said value is greater than the predetermined level Vc, advance is made to a step  204 . At the step  204  to step  209 , as in the case of FIG. 2, the image stabilizing operation is started at a point of time at which the output of the angle deviation detecting means has fallen within a predetermined level range. 
     Also, if at the step  202 , the latch ISONL is at an H level, advance is made to a step  261 . 
     Steps  261  and  211 - 216  are the termination routine of the image stabilizing operation, and at the step  216 , whether the value of the source voltage Vcc is below a predetermined level is judged, and if the source voltage Vcc is greater than the predetermined level Vc, return is made to the step  202 , where the image stabilizing operation is continued, but if the source voltage Vcc becomes smaller than the level Vc, advance is made to the step  211 . 
     At the step  211  to the step  216 , as in the case of FIG. 2, the image stabilizing operation is terminated at a point of time at which the output of the angle deviation detecting means has fallen within a predetermined level range. 
     Accordingly, again in the present embodiment, as in the previous embodiments, discontinuity of the viewfinder image occurs during neither of the starting and termination of the image stabilizing operation. 
     In each of-the above-described embodiments, in order to shorten the time lag during the starting or the termination of the image stabilizing operation, the angle deviation detecting means may be forcibly driven by driving means like that in the following embodiment so that the output thereof may fall within a predetermined level in a short time. 
     FIG. 7 is a block diagram schematically showing the construction of an image stabilizing device according to yet still another embodiment of the present invention. In FIG. 7, the output of vibration detector means  150  for detecting the amount of deviation relative to the absolute space of the camera is input to amplifier means  154  whose amplification rate varies for a predetermined time depending on the state of selector means  156 , and the output of this amplifier means is input to calculator means  155 . On the other hand, the amount of movement of optical compensator means  151  for compensating for the vibration of an image through the photo-taking lens is detected by position detector means  153 , the output of which is input to the calculator means  155 . In the calculator means  155 , calculation is effected on the basis of the output of the amplifier means  154  and the output of the position detector means  153 , and the output of the calculator means  155  is input to driver means  152 . The driver means  152  drives the optical compensator means  151  and forms a feedback loop as shown. 
     An embodiment of the specific construction of FIG. 7 is shown in FIG.  8 . 
     The construction of FIG. 8 is similar to the construction of FIG. 1, except for the points which will hereinafter be described. 
     In FIG. 8, the reference numeral  102  designates an A/D converter to which a positive reference voltage KVC and a negative reference voltage −KVC are input as reference voltage levels. The angle deviation output of the angle deviation detecting means is A/D-converted by the input of a control signal ADST1 from the CPU  100 , and the amount of angle deviation of the variable vertical angle prism  41  is A/D-converted by the input of a control signal ADST2 from the CPU  100 . At the end of the A/D-converting operation, the output ADEND thereof assumes an H level and the result of the A/D conversion is transmitted to the CPU  100  through ADDATA. 
     The reference numeral  105  denotes an interrupt timer  1  which applies the interrupt operation to the CPU  100  at a predetermined time interval T 1  to execute the A/D-converting operation for the amount of angle deviation of the angle deviation detecting means and the control calculation for the angle deviation detecting means. 
     The reference numeral  106  designates an interrupt timer  2  which applies the interrupt operation to the CPU  100  at a predetermined time interval T 2  to effect the A/D converting operation for the amount of angle deviation of the angle deviation detecting means and the amount of angle deviation of the variable vertical angle prism  41  and the phase compensation calculation for executing the feedback control of the variable vertical angle prism. 
     The reference numeral  103  denotes PWM timer  1  which receives from the CPU  100  the result of the control calculation to the angle deviation detecting means effected in the CPU  100 , outputs a value corresponding to said result by varying the duty cycle in a predetermined periodic clock, and determines a driving current value to a driver circuit for the angle deviation detecting means which will be described later. 
     The reference numeral  104  designates PWM timer  2  which receives from the CPU  100  the result of the control calculation for the amount of angle deviation of the variable vertical angle prism  41  calculated in the CPU  100 , outputs a value corresponding to said result by varying the duty cycle in a predetermined periodic clock, and determines a driving current value to a driver circuit for driving the variable vertical angle prism which will be described later. 
     A power amplifying circuit comprised of an operational amplifier  32  and transistors  33  and  34  is a driver circuit for the angle deviation detecting means for supplying a predetermined electric current to a driving coil  7  integral with a yoke  8  fixed to the case  2  for controlling the characteristic of the angle deviation detecting means, and supplies the coil  7  with an electric current corresponding to the duty cycle value of the PWM timer  1  because the output of the PWM timer  1  is converted into an analog voltage by a low-pass filter comprised of a resistor  35  and  1 S a capacitor  36  and that analog potential is connected to the non-inverting input terminal of the operational amplifier  32 , whereby the movement characteristic of the float  3  is controlled by Lorentz&#39;s force and the vibration detection characteristic of the angle deviation detecting means is rendered adequate. 
     A power amplifying circuit comprised of an operational amplifier  110  and transistors  113  and  114  is a driver circuit for the variable vertical angle prism for supplying a predetermined electric current to a driving coil  98  for controlling the driving of the variable vertical angle prism  41 , and supplies the coil  98  with an electric current corresponding to the duty cycle value of the PWM timer  2  because the output of the PWM timer  2  is converted into an analog voltage by a low-pass filter comprised of a resistor  112  and a capacitor  113  and that analog potential is connected to the non-inverting input terminal of the operational amplifier  110 , whereby the variable vertical angle prism  41  is driven for image vibration compensation. The reference numeral  120  designates an extraneously operated IS switch for directing the starting and termination of the image stabilizing operation, and the reference numeral  121  denotes an extraneously operated FADE switch for gradually connecting or disconnecting the output of the angle deviation detecting means to the feedback loop of the variable vertical angle prism  41  and selecting whether the discontinuity of the viewfinder image should be prevented. 
     The operation of the construction of FIG. 8 will now be described with reference to the flow charts of FIGS. 10,  11 ,  12  and  13  which show the operation of the CPU  100 . 
     First, in FIG. 10, each coefficient data for executing the digital calculation in the CPU  100  is read out from an ROM in the CPU  100  and is set in an internal memory. In a flow  300 , the gain GK of a proportional term for controlling the coil  7  of the angle deviation detecting means is first set in an internal memory M(k1). 
     Subsequently, in flows  301 - 305 , calculation data for effecting the differential control of the coil  7  of the angle deviation detecting means is set in each internal memory, and in the flow  301 , the gain GH of a differential term is set in an internal memory M(H1). Subsequently, a coefficient for effecting actual differential calculation is set by flows  302 - 304 , and here, analogously expressing a differentiation circuit, it is expressed by a primary advance circuit as shown in FIG. 9A (for a frequency sufficiently lower than a pole frequency, the same as a differentiation circuit), and expressing the frequency characteristic H(S) as the coefficient of H(Z) on Z-plane by the use of known S-Z conversion, with the sample time interval as T 1 , it is:              A0H   =       2     T   1           1       C   1          R   1         +     2     T   1                       A1H   =       -     2     T   1             1       C   1          R   1         +     2     T   1                       B1H   =         1       C   1          R   1         -     2     T   1             1       C   1          R   1         +     2     T   1                                        
     Accordingly, in the flow  302 , the constant data A0H is set in a memory M(H2), and in the flow  303 , the constant data A1H is set in a memory M(H3), and in the flow  304 , the constant data B1H is set in a memory M(H4), and further in the flow  305 , an internal memory M(H5) for memorizing the intermediate result of calculation is reset to 0. 
     Subsequently, in flows  306 - 310 , calculation data for effecting the integral control of the coil  7  of the angle deviation detecting means is set in each internal memory, and first in the flow  306 , the gain GT of an integral term is set in an internal memory M(T1). Next, a coefficient for effecting actual integral calculation is set by the flows  307 - 309 , and here, analogously expressing an integration circuit, it is expressed by a primary delay circuit as shown in FIG. 9B (for a frequency sufficiently higher than the pole frequency, the same as an integration circuit), and expressing the frequency characteristic H(S) thereof as the coefficient of H(Z) on Z-plane by the use of known S-Z conversion, with the sampling time interval as T 1 , it is:              A0T   =       1       C   2          R   2             1       C   2          R   2         +     2     T   1                       A1T   =       1       C   2          R   2             1       C   2          R   2         +     2     T   1                       B1T   =         1       C   2          R   2         -     2     T   1             1       C   2          R   2         +     2     T   1                                        
     Accordingly, in the flow  307 , the constant data A0T is set in a memory M(T2), and in the flow  308 , the constant data A1T is set in a memory M(T3), and in the flow  309 , the constant data B1T is set in a memory M(T4), and further in the flow  310 , an internal memory M(T5) for memorizing the intermediate result of calculation is reset to 0. 
     Further, in flows  311 - 315 , in order to realize phase advance compensation necessary for the feedback control of the variable vertical angle prism  41 , in the flow  311 , the feedback loop gain GS of the whole including the gain of phase advance compensation is first set in an internal memory M(S1). 
     Next, a coefficient for effecting actual phase advance compensation calculation is set in each internal memory by the flows  312 - 314 , and here, analogously expressing a phase advance compensation circuit, it is expressed by a circuit as shown in FIG. 9C, and expressing the frequency characteristic H(S) thereof as the coefficient of H(Z) on Z-plane by the use of known S-Z conversion, with the sampling time interval as T 2 , it is:              A0S   =         1       C   3          R   3         +     2     T   2                 R   3     +     R   4           C   3          R   3          R   4         +     2     T   2                       A1S   =         1       C   3          R   3         -     2     T   2                 R   3     +     R   4           C   3          R   3          R   4         +     2     T   2                       A2S   =             R   3     +     R   4           C   3          R   3          R   4         -     2     T   2                 R   3     +     R   4           C   3          R   3          R   4         +     2     T   2                                        
     Accordingly, in the flow  312 , the constant data AOS is set in a memory M(S2), and in the flow  313 , the constant data A1S is set in a memory M(S3), and in the flow  314 , the constant data BIS is set in a memory M(S4), and further in the flow  315 , an internal memory M(S5) for memorizing the intermediate result of calculation is reset to 0. 
     Subsequently, in flows  316 - 323 , an interruption timer for setting the sampling time interval is started. First, in the flow  316 , the sampling time T 1  is set in an internal A register, and subsequently, in order to transmit this set value to an interruption timer  1  designated by  105 , INST1 output is rendered into an H level in the flow  317 . Further, in the flow  318 , the value of the A register is transmitted to the interruption timer  1  through INDATA1, and in the flow  319 , the INST1 output is rendered into an L level and the interruption timer  1  is started. 
     Likewise, in the flow  320 , the sampling time T 2  (T 2 &lt;T 1 ) is set in the internal A register and subsequently, in order to transmit this set value to an interruption timer  2  designated by  106 , INST2 output is rendered into an H level in the flow  321 . Further, in the flow  322 , the value of the A register is transmitted to the interruption timer  2  through INDATA2, and in the flow  323 , the INST2 output is rendered into an L level and the interruption timer  2  is started. 
     In this manner, the interruption timers generating interruption at each predetermined time are started, and then the interruption process is carried out while the main operation is executed. 
     Subsequently, in a flow  324 , a memory M(M1) for memorizing the state of the IS switch  120  shown in FIG. 8 is reset to 0, and in a flow  325 , a memory M(M2) for controlling the operation of the present embodiment by the state of FADE switch  121  is reset to 0. 
     FIG. 11 shows the main operation of the CPU  100 . First, in a flow  330 , set time data T F  for judging the value of an internal timer  401  is set in an internal memory M(M3), and in a flow  331 , set time data T CH  is like wise set in an internal memory M(M4). 
     Next, in a flow  332 , the state of an internal memory M(M1) is judged, and if the value of this memory is reset to 0, the state of the IS switch  120  is judged in a flow  333 . If here, the IS switch  120  is OFF, return is only made to the flow  332 , but if the IS switch  120  is ON, it is judged that the state of this switch has changed from OFF to ON, and in a flow  334 , the value of the internal memory M(M1) is set to 1, and then advance is made to a flow  337 . On the other hand, if in the flow  332 , the internal memory M(M1) is already set to 1, the state of the IS switch  120  is judged in a flow  335 . If here, the IS switch  120  is ON, return is made to the flow  332 , but if the IS switch  120  is OFF, it is judged that the state of this switch has changes from ON to OFF, and in a flow  336 , the value of the internal memory M(M1) is reset to 0 and advance is made to a flow  337 . In the flow  337 , the internal timer  101  in the CPU  100  shown in FIG. 8 is started from 0, and then in a flow  338 , the state of FADE switch  121  is judged. If the FADE switch  121  is OFF, control for gradually changing over the starting/stoppage of the image stabilizing operation as described in t he present embodiment is not exe cuted and therefore, in a flow  342 , the value of the internal timer  101  is compared with the value of a memory M(M4) in which the data value T CH  is substituted for in advance, and at a time at which the two values coincide with each other, advance is made to a flow  344 , where the internal timer is stopped and return is made to the flow  332 . 
     If in the flow  338 , the FADE switch  121  is ON, the value of the internal memory M(M2) is set in a flow  339 , and subsequently in a flow  340 , the value of the internal timer  101  is compared with the effected in the interruption process of the interruption timer  2  which will be described later until the value of the internal timer  101  coincides with the value of the internal memory M(M3). When the value of the internal timer  101  becomes equal to the value of the memory M(M3), advance is made to a flow  341 , where the value of the memory M(M2) is reset to 0, and in a flow  343 , the internal timer is stopped, and then return is made to the flow  332 . 
     FIG. 12 shows the flowchart of the interruption process by the interruption timer  1 . First, in a flow  350 , ADST1 output is rendered into an H level, thereby starting the operation of the A/D converter  102 . The A/D converter  102  A/D-converts the output of the operational amplifier  16 , and renders ADEND output into an H level at a point of time whereat the A/D conversion is terminated. The CPU  100 , when it detects in a flow  351  that the ADEND output of the A/D converter  102  has assumed as H level, immediately introduces that digital converted value into A register through ADDATA in a flow  352 , and renders ADST1 output into an L level in a flow  353 , thus terminating the A/D converting operation. 
     Next, flows  354 - 364  are a calculating portion for actually executing the P1D control of the angle deviation detecting means. First, in the flow  354 , the value of A register in which the deviation output of the angle deviation detecting means is set is multiplied by the value of a memory M(K1) in which the gain of a proportional term is set, and the result thereof is set in B register and proportional calculation is executed. 
     Subsequently, in the flow  355 , the value of a memory M(H4) in which the aforementioned differential calculation coefficient B1H is set, multiplied by the value of a memory M(H5) memorizing therein the intermediate result of the differential calculation effected in the last interruption process operation, is subtracted from the value of A register in which the deviation output of the angle deviation detecting means, and the result of the subtraction is set in C register. 
     In the flow  356 , the value of the memory M(H5) multiplied by the value of a memory M(H3) in which the aforementioned calculation coefficient A1H is set is added to the value of C register multiplied by the value of a memory M(H2) in which the aforementioned differential calculation coefficient A0H is set, and the result of the addition is set in D register. Further, in the flow  357 , the value of this D register is multiplied by the value of a memory M(H1) in which the gain of differential term is set, and the result of the multiplication is again set in D register, and in the flow  358 , the value of this D register is added to the value of B register in which the result of proportional calculation is set, and the result of the addition is again set in B register. In the flow  359 , the value of C register memorizing therein the intermediate result of the differential calculation effected in the current interruption process operation is set in a memory M(H5) so as to be used in the next interruption process operation. 
     Likewise in the integral calculation of flows  360 - 364 , first in the flow  360 , the value of a memory M(T4) in which the aforementioned integral calculation coefficient B1T is set, multiplied by the value of a memroy M(T5) memorizing therein the intermediate result of the integral calculation effected in the last interruption process operation, is subtracted from the value of A register in which the deviation output of the angle deviation detecting means is set, and the result of the subtraction is set in C register. In the flow  361 , the value of the memory M(T5) multiplied by the value of a memory M(T3) in which the aforementioned integral calculation coefficient A1T is set is added to the value of C register multiplied by the value of a memory M(T2) in which the aforementioned differential calculation coefficient A0T is set, and the result of the addtion is set in D register. 
     Further, in the flow  362 , the value of D register is multiplied by the value of a memory M(T1) in which the gain of integral term is set, and the result of the multiplication is again set in D register, and in the flow  363 , the value of this D register is added to the value of B register in which the addition of the proportional calculation to the differential calculation is already set, and the result of this addition is again set in B register. In the flow  364 , the value of C register memorizing therein the intermediate result of the integral calculation effected in the current interruption process operation is set in a memory M(T5) so as to be used in the next interruption process operation. 
     Subsequently, in order that the result obtained by P1D-calculating the output of the angle deviation detecting means may be transmitted to PWM timer  1  designated by  103 , in a flow  365 , PWMST1 output is rendered into an H level, and in a flow  366 , the value of B register is transmitted to the PWM timer  1  through PWMDATA  1 , whereafter in a flow  367 , the PWMST1 output is rendered into an L level, thus terminating the interruption process by this interruption timer  1 . 
     Here, the output of this PWM timer  1  designated by  103  corresponds to data whose duty cycle values of H and L levels have been input at a clock of a predetermined period and thus, the output of a low-pass filter comprised of a resistor  35  and a capacitor  36  is an analog output proportional to these duty cycle values. A power amplifying circuit of the push-pull type is constituted by an operational amplifier  32  and transistors  33  and  34 , and the output of the low-pass filter is connected to the non-inverting input terminal of the operational amplifier  32  and thus, an electric current corresponding to the result calculated by the CPU  100  is supplied to the coil  7 , and the feedback loop as shown in FIG. 7 is formed. 
     FIG. 13 shows the flow chart of the interruption operation by the interruption timer  2 . First, in a flow  400 , ADST1 output is rendered into an H level, whereby the operation of the A/D converter  102  is started. The A/D converter  102  A/D-converts the output value of the angle deviation detecting means from the output of the operational amplifier  16 , and renders the ADEND output into an H level at a point of time at which the conversion is terminated. 
     The CPU  100 , when in a flow  401 , it detects that the ADEND output of the A/D converter  102  has assumed an H level, immediately introduces, in a flow  402 , the digital converted value into A register through ADDATA, and in a flow  403 , renders ADST1 output into an L level, thus terminating the A/D converting operation. 
     Subsequently, in a flow  404 , ADST2 output is rendered into an H level, whereby the operation of the A/D converter  102  is started. The A/D converter  102  A/D-converts the deviation output value of the variable vertical angle prism  41  from the output of the operational amplifier  56 , and renders the ADEND output into an H level at a point of time at which the conversion is terminated. The CPU  100 , when in a flow  405 , it detects that the ADEND output of the A/D converter  102  has assumed an H level, immediately introduces, in a flow  406 , the digital converted value into an M register through ADDATA, and in a flow  407 , renders the ADST2 output into an L level, thus terminating the A/D converting operation. 
     Next, in a flow  408 , the value of the memory M(M2) is judged, and if it is reset to 0, it is judged that the control of a variation in the gain with time in the present embodiment is terminated or non-selected, and advance is made to a flow  409 . If here, the value of the internal memory M(M1) is reset to 0, the output data of the angle deviation detecting means is fixed at 0 to stop the image stabilizing operation, and the value of the M register in which the deviation data of the variable vertical angle prism  41  is set is subtracted from this value, and the result of the subtraction is set in N register. Also, if the value of the memory M(M1) is set to 1, in a flow  411 , the value of M register in which the deviation data of the variable vertical angle prism  41  is set is subtracted from the value of K register in which the output data of the angle deviation detecting means is set, in order to start the image stabilizing operation, and the difference therebetween is set in N register. 
     On the other hand, if in the flow  408 , the value of the memory M(M2) is set to 1, the count value of the internal timer  101  which has already been started in the flow chart of FIG. 11 is first transmitted to X register in a flow  412  to execute the control of a variation in the gain with time relative to the output of the angle deviation detecting means. Subsequently, in a flow  413 , the value of the memory M(M1) which indicates whether the image stabilizing operation should be started or stopped is judged, and if this value is reset to 0, in a flow  414 , the value of X register is divided by the value of the memory M(M3) in which predetermined data T F  is set, and a value obtained by subtracting the result of the division from 1 is again set in X register. Also, if in the flow  413 , the value of the memory M(M1) is set to 1, in a flow  415 , the result obtained by dividing the value of X register by the value of the internal memory M(M3) is again set in X register. The interruption operation of the interruption timer  2  is executed at predetermined intervals and thus, the value of the internal timer  101  transmitted to X register in the flow  412  increases by a predetermined number. This control operation is executed until the value of the internal timer  101  coincides with the value of the internal memory M(M3) and therefore, when the flow  414  is passed through, the value of X register decreases at an equal interval from 1 to 0, and when the flow  415  is passed through, said value increases at an equal interval from 0 to 1. In a flow  416 , the value of X register as an amplification rate which varies with time is multiplied by the value of K register in which the output data of the angle deviation detecting means is set, and the value of M register in which the deviation data of the variable vertical angle prism  41  is set is subtracted from the result of multiplication, and the value thus obtained is set in N register. 
     Thus, with  1  being set in the internal memory M(M2), as described above, at the start of the image stabilizing operation, the output of the angle deviation detecting means is gradually applied to the feedback loop of the variable vertical angle prism  41  with time, and at the termination of the image stabilizing operation, the output of the angle deviation detecting means is gradually disconnected from the feedback loop of the variable vertical angle prism  41  with time. 
     In flows  417 - 420 , in order to achieve the feedback control of the variable vertical angle prism  41 , the phase advance compensation as shown in FIG. 9C is digitally calculated in the necessary phase compensation calculating portion. First, in the flow  417 , the value of a memory M(S4) in which the aforementioned phase compensation calculation coefficient B1S is set, multiplied by the value of a memory M(S5) memorizing therein the intermediate result of the integration effected in the last interruption process operation, is subtracted from the value of N register in which is set the difference between the deviation output of the angle deviation detecting means multiplied by a certain gain and the deviation output of the variable vertical angle prism  41 , and the result of the subtraction is set in S register. In the flow  418 , the value of the memory M(S5) multiplied by the value of a memory M(S3) in which the aforementioned phase compensation calculation coefficient A1S is set is added to the value of S register multiplied by the value of a memory M(S2) in which the aforementioned phase compensation calculation coefficient A0S is set, and the result of the addition is set in T register. Further, in the flow  419 , the value of this T register is multiplied by the value of a memory M(S1) in which is set the feedback gain including phase compensation, and the result of this multiplication is again set in T register, and in the flow  420 , the value of S register memorizing therein the intermediate result of the phase compensation calculated in the current interruption process operation is set in a memory M(S5) so as to be used in the next interruption process operaiton. 
     Subsequently, in a flow  421 , PWMST2 output is rendered into an H level in order to transmit this calculated result to PWM timer  2  designated by  104 , and in a flow  422 , the value of T register is transmitted to the PWM timer  2  through PWMDATA 2, whereafter in a flow  423 , the PWMST2 output is rendered into an L level, thus terminating the interruption operation by the interruption timer  2 . 
     Here, the output of this PWM timer  2  designated by  104  is a clock of a predetermined period, and corresponds to data to which the duty cycle values of H and L levels thereof have been input and therefore, the output of a low-pass filter comprised of a resistor  112  and a capacitor  111  is an analog output proportional to said duty cycle values. A power amplifying circuit of the push-pull type is constituted by an operaitonal amplifier  110  and transistors  113  and  114 , and the output of the low-pass filter is connected to the non-inverting input terminal of the operational amplifier  110  and thus, an electric current corresponding to the value of T register which is the calculated result is supplied to the coil  98 . 
     Thus, in the present embodiment, the output of the angle deviation detecting means is multiplied by a coefficient whose value changes between 0 to 1 or between 1 to 0 at equal intervals for a predetermined period in conformity with a variation in the state of the outside switch which expedites the starting/stoppage of the image stabilizing operation, and the result of this multiplication is applied to the feedback loop of the variable vertical angle prism  41  and therefore, at the start of the image stabilizing operation, the output of the angle deviation detecting means is connected to the feedback loop of the variable vertical angle prism  41  gradually and in a predetermined time, and at the termination of the image stabilizing operation, the output of the angle deviation detecting means is disconnected from the feedback loop of the variable vertical angle prism  41  gradually and in a predetermined time, and the occurrence of the discontinuity of the viewfinder image at the start or termination of the image stabilizing operation can be prevented. 
     Another embodiment of the operation of the FIG. 8 circuit will now be described with reference to the flow charts of FIGS. 14 and 15 which show the operation of the CPU  100 . 
     FIG. 14 shows the main operation of the CPU  100 . In a flow  500 , the set time T CH  for judging the value of the internal timer  101  is set in an internal memory M(M4), and in a flow  501 , step data MD for gradually executing the starting/stoppage of the image stabilizing operation is se t in the memory M(M5). 
     Flows  502 - 506  are similar to the flows  332 - 336  of FIG. 11, and in these flows, it is detected that the state of the IS switch  120  has changed, and the value of the memory M(M1) is changed over. 
     In a flow  507 , the state of FADE switch  121  is judged, and if this FADE switch  121  is OFF, the control for gradually changing over the starting/stoppage of the image stabilizing operation is not executed as in the embodiment of FIG.  11  and therefore, in a flow  511 , the internal timer  101  is started to absorb merely chattering of the switch, and in a flow  512 , the program waits until the value of the timer  101  coincides with the value of the memory M(M4). At a point of time at which the value of the timer  101  coincides with the value of the memory M(M4), advance is made to a flow  513 , where the internal timer  101  is stopped, and advance is again made to the flow  502 . 
     On the other hand, if in the flow  507 , the FADE switch  121  is ON, in a flow  508 , the value of the memory M(M2) is set to 1, and subsequently in a flow  509 , the value of X register necessary to execute the actual control of the present embodiment is reset to 0. In a flow  510 , whether the value of the memory M(M2) has become 0 is judged, and at a point of time at which the control of gradually executing the starting/stoppage of the image stabilizing operation during the change-over of the switch in the interruption operation of the interruption timer  2  which will be described later, the value of the memory M(M2) is reset to 0, and return is made to the flow  502  after the flow  510  has been passed through. 
     FIG. 15 shows the flow chart of the interruption operation by the interruption timer  2 . Flows  550 - 557  are entirely similar to the flows  400 - 407  of FIG. 13, and the results of the A/D conversions of the output of the angle deviation detecting means and the deviation output of the variable vertical angle prism  41  are set in K register and M register, respectively. 
     Subsequently, in a flow  558 , the value of the memory M(M2) is judged, and if this value is reset to 0, it is judged that the control of gradually executing the starting/stoppage of the image stabilizing operation in the present embodiment is terminated or non-selected, and as in the flows  409 - 411  of FIG. 13, flows  559 - 561  are executed and advance is made to a flow  570 . 
     On the other hand, if in the flow  558 , the value of the memory M(M2) is set to  1 , the control of a variation in the gain with time is executed relative to the output of the angle deviation detecting means and therefore, if in a flow  562 , the value of K register is negative, in a flow  563 , the value of the memory M(M5) in which the value of step data MD is preset is subtracted from the value of X register and the result of the subtraction is again set in X register, but if in the flow  562 , the value of K register is positive, in a flow  564 , the value of the memory M(M5) is added to the value of X register and the result of the addition is again set in X register. In a flow  565 , whether the value of X register is equal to the value of K register as the output data of the angle deviation detecting means is judged, and if the former value is equal to the latter value, it is judged that the control of the variation in the gain with time resulting from the change in the state of the switch has been terminated, and after in a flow  566 , the memory M(M2) is reset to 0, the operations of the flows  559  and so on are executed. If in the flow  565 , the value of K register differs from the value of X register, the value of the memory M(M1) is judged in a flow  567 , and if here, the value of the memory M(M1) is reset to 0, in a flow  568 , the value of X register is subtracted from the value of K register in which the output data of the angle deviation detecting means is set, in order to gradually stop the image stabilizing operation, and from the result of this subtraction, the value of M register in which the deviation data of the variable vertical angle prism  41  is set is further subtracted, and the result of this subtraction is set in N register. 
     Also, if the value of the memory M(M1) is set to 1, in a flow  569 , the value of M register in which the deviation data of the variable vertical angle prism  41  is set is subtracted from the value of X register, in order to gradually start the image stabilizing operation, and the result of this subtraction is set in N register. 
     The phase compensation calculation of flows  570 - 576  and the method of driving the driver circuit through the PWM timer  2  are similar to the flows  417 - 423  of the FIG. 13 embodiment, and phase compensation calculation for achieving the feedback loop of the variable vertical angle prism  41  is applied to the value set in N register, whereafter the output thereof is put out through the PWM timer  2 . 
     Thus, in the present embodiment, the step data MD set in the memory M(M5) is added or subtracted in conformity with the change in the state of the outside switch which expedites the starting/stoppage of the image stabilizing operation each time the interruption operation of the timer  2  is executed. The variable vertical angle prism  41  is driven on the basis of the cumulative data and therefore, at the start of the image stabilizing operation, the output of the angle deviation detecting means is connected to the feedback loop of the variable vertical angle prism  41  gradually and at a predetermined rate to time, and at the termination of the image stabilizing operation, the output of the angle deviation detecting means is disconnected from the feedback loop of the variable vertical angle prism  41  gradually and at a predetermined rate to time, and the occurrence of the discontinuity of the viewfinder image at the start or termination of the image stabilizing operation. 
     Still another embodiment of the operation of the circuit of FIG. 8 will now be described with reference to the flow chart of FIGS. 16 and 17 which show the operation of the CPU  100 . 
     FIG. 16 shows the main operation, and flows  600 - 606  are similar to the flows  500 - 506  of FIG.  14 . 
     In a flow  607 , the state of FADE switch  121  is judged, and if this switch  121  is OFF, flows  1612 - 614  are executed as in the flows  511 - 513  of FIG. 14, and the absorption of the chattering of the switch is executed and return is made to the flow  602 . 
     If in the flow  607 , FADE switch  121  is ON, in a flow  608 , the value of the memory M(M2) is set to 1, and subsequently in flows  609  and  610 , both the value of X register and the value of Y register necessary to execute the actual control of the present embodiment is reset to 0. 
     In a flow  611 , whether the value of the memory M(M2) has become 0 is judged, and at a point of time at which in the interruption operation of the interruption timer  2 , the value of the memory M(M2) has been reset to 0, return is made from the flow  611  to the flow  602 . 
     FIG. 17 shows the flow chart of the interruption operation of the interruption timer  2 , and flows  650 - 661  are similar to the flows  400 - 411  of the FIG. 13 embodiment and to the flows  550 - 561  of the FIG. 15 embodiment. The results of the A/D conversions of the output of the angle deviation detecting means and the deviation output of the variable vertical angle prism  41  are set in K register and M register, respectively, and if in the flow  658 , the memory M(M2) is reset to 0, it is judged that the control of the starting/stoppage of the image stabilizing operation is terminated or non-selected, and flows  659 - 661  are executed and thereafter, advance is made to a flow  671 . 
     On the other hand, if in the flow  658 , the value of the memory M(M2) is set to 1, in a flow  662 , the value of Y register which is reset to 0 in advance in the main process is counted up by 1 in order to execute the control of a variation in the gain with time relative to the output of the angle deviation detecting means. If in a flow  663 , the value of K register is negative, in a flow  664 , the result obtained by dividing the value of the memory M(M5) in which the value of step data MD is preset by the value of Y register is subtracted from X register, and that value is again set in X register. 
     Also, if in the flow  663 , the value of K register is positive, the result obtained by dividing the value of the memory M(M5) by the value of Y register is added to X register, and that value is again set in X register. In a flow  666 , whether the value of X register is equal to the value of K register as the output data of the angle deviation detecting means is judged, and if the former value is equal to the latter value, in a flow  667 , the memory M(M2) is reset to 0, and then the operation of the flow  659  is executed. If in the flow  666 , the value of K register differs from the value of X register, the value of the memory M(M1) is judged in a flow  668 , and if in this flow, the value of the memory M(M1) is reset to 0, in a flow  669 , the value of X register and the value of M register are subtracted from the value of K register in order to gradually stop the image stabilizing operation on the basis of the value of X register, and the result of the subtraction is set in N register. Also, if the value of the memory M(M1) is set to 1, in a flow  670 , the value of M register is subtracted from the value of X register in order to gradually start the image stabilizing operation, and the result of this subtraction is set in N register. 
     The phase compensation calculation of flows  671 - 677  and the driving method of the driver circuit through PWM timer  2  are similar to the flows  417 - 423  of the FIG. 13 embodiment. 
     Thus, in the present embodiment, in conformity with a change in the state of the outside switch which expedites the starting/stoppage of the image stabilizing operation, the result obtained by dividing step data MD set in register M(M5) by the value of Y register which increases each time the interruption operation is executed is added or subtracted each time the interruption operation is executed, and on the basis of the cumulative data thereof, the variable vertical angle prism  41  is driven and therefore, at the start of the image stabilizing operation, the output of the angle deviation detecting means is connected to the feedback loop of the variable vertical angle prism  41  gradually and more slowly in the second half than in the first half, and at the termination of the image stabilizing operation, the output of the angle deviation detecting means is disconnected from the feedback loop of the variable vertical angle prism  41  gradually and more slowly in the second half than in the first half, and the occurrence of the discontinuity of the viewfinder image at the start or termination of the image stabilizing operation can be prevented. 
     The present invention is not restricted to the above-described embodiments, but of course, the present invention can be applied, for example, to devices using any type of image vibration detecting means or any type of image vibration compensating means, and may be directed to any optical instrument.