Patent Abstract:
A camera system is disclosed, which comprises a camera having a vibration detection unit which detects vibration, and a vibration correction unit which is attachable to the camera and has a vibration correction optical system which corrects image vibration and a driving control circuit which drives the vibration correction optical system based on a vibration detection signal from the vibration detection unit. The camera intermittently transmits the vibration detection signal from the vibration detection unit and time-related data to the driving control circuit. The driving control circuit receives the vibration detection signal and the time-related data. The driving control circuit drives the vibration correction optical system based on a previously received vibration detection signal or a currently received vibration detection signal selected on the basis of the received time-related data.

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an improvement of a camera system having a correcting image vibration function. 
     2. Description of the Related Art 
     A conventionally well-known vibration correction function in a camera system is configured such that an interchangeable lens contains a vibration sensor for detecting camera shake, and a vibration correction optical system formed of all or some of an image-taking optical system is driven in response to output from the vibration sensor. 
     In addition, various proposals have been made for an image vibration correction system having a vibration sensor in a camera and a correction optical system in a lens in which vibration information is transmitted from the camera to the lens through a signal line to control the vibration correction in the lens based on the transmitted data, for example in Japanese Patent Application Laid-Open No. 7-191354 (U.S. Pat. No. 6,088,533). 
     Such an image vibration correction system having a vibration sensor in a camera and a correction optical system in a lens as mentioned above is based on the premise that data of vibration detected by the vibration sensor in the camera or a signal for driving the correction optical system is transmitted to the lens at regular intervals. The actual working of a camera working, however, involves a number of control operations other than vibration correction, such as an autofocus operation, so that it is not necessarily possible to continue the transmission of the vibration data to the lens at regular intervals. In this event, if vibration data transmitted after some delay is used in calculations to drive the correction system, the control of the correction system which should be performed at regular intervals is delayed, and also, the resultant correction amount may be different from an amount which should actually be used for correction since the calculations of the correction amount is premised on correction performed at regular intervals. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a camera system which can prevent against deteriorated accuracy of vibration correction even when vibration data cannot be transmitted to a vibration correction unit at regular intervals. 
     The present invention is characterized by a camera system comprising: a camera having as a vibration detection unit which detects vibration, and a vibration correction unit which is attachable to the camera and has a vibration correction optical system which corrects image vibration and a driving control circuit which drives the vibration correction optical system based on a vibration detection signal from the vibration detection unit. The camera intermittently transmits the vibration detection signal from the vibration detection unit and time-related data to the driving control circuit, and the driving control circuit receives the vibration detection signal and the time-related data. 
     The present invention is also characterized in that the driving control circuit drives the vibration correction optical system based on a previously received vibration detection signal or a currently received vibration detection signal selected on the basis of the received time-related data. 
     The present invention is also characterized in that the time-related data is time data which represents a delay time period after a predetermined timing at which the camera should essentially transmit the vibration detection signal to the driving control circuit. The driving control circuit drives the vibration correction optical system based on the currently received vibration detection signal when the time data is equal to or smaller than a predetermined value, and drives the vibration correction optical system based on the previously received vibration detection signal when the time data is larger than the predetermined value. 
     The present invention is also characterized in that the vibration correction unit and the driving circuit are included in an interchangeable lens unit having an image-taking optical system. 
     In addition, the present invention is characterized by a camera system comprising: a camera having a vibration detection unit which detects vibration, and an interchangeable lens unit which is attachable to the camera and has a vibration correction optical system which corrects image vibration and a driving control circuit which drives the vibration correction optical system based on a vibration detection signal from the vibration detection unit. The camera intermittently transmits the vibration detection signal from the vibration detection unit and time-related data to the driving control circuit, and the driving control circuit receives the vibration detection signal and the time-related data. 
     Further, the present invention is characterized by a vibration correction unit attachable to a camera having a vibration detection unit which detects vibration, comprising: a vibration correction optical system which corrects image vibration; and a driving control circuit which drives the vibration correction optical system based on a vibration detection signal from the vibration detection unit. The driving control circuit receives the vibration detection signal and time-related data transmitted intermittently from the camera. 
     Further, the present invention is characterized by an interchangeable lens attachable to a camera having a vibration detection unit which detects vibration, comprising: a vibration correction optical system which corrects image vibration; and a driving control circuit which drives the vibration correction optical system based on a vibration detection signal from the vibration detection unit. The driving control circuit receives the vibration detection signal and time-related data transmitted intermittently from the camera. 
     Further, the present invention is characterized by a camera to which a vibration correction unit or an interchangeable lens can be attached. The vibration correction unit or the interchangeable lens has a vibration correction optical system which corrects image vibration and a driving control circuit which drives the vibration correction optical system. The camera comprising: a vibration detection unit which detects vibration; and a camera control circuit which intermittently transmits a vibration detection signal from the vibration detection unit and time-related data to the driving control circuit. 
     Additional characteristics of the present invention will be apparent from the following description with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram showing the configuration of a camera system according to an embodiment of the present invention; 
     FIG. 2 shows the configuration of an angular velocity sensor of the camera system according to the embodiment of the present invention; 
     FIG. 3 specifically shows the configuration of a vibration correction unit of the camera system according to the embodiment of the present invention; 
     FIG. 4 shows a timing chart of the communication in the camera system according to the embodiment of the present invention; 
     FIGS.  5 (A) and  5 (B) show a flow chart of the operation of camera-side main processing in the camera system according to the embodiment of the present invention; 
     FIG. 6 shows a flow chart of the operation of camera-side timer interrupt processing in the camera system according to the embodiment of the present invention; 
     FIG. 7 shows a flow chart of the operation of lens-side main processing in the camera system according to the embodiment of the present invention; 
     FIGS.  8 (A) and  8 (B) show a flow chart of the operation of lens-side serial interrupt processing in the camera system according to the embodiment of the present invention; 
     FIG. 9 shows a flow chart of the operation subsequent to the operation in FIG. 8; 
     FIG. 10 shows a flow chart of the operation of a data conversion subroutine on vibration data in the camera system according to the embodiment of the present invention; and 
     FIG. 11 shows a flow chart of the operation of a feedback calculation subroutine of the vibration correction unit in the camera system according to the embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is hereinafter described in detail on the basis of an embodiment shown in the accompanying drawings. 
     FIG. 1 is a block diagram generally showing the configuration of a camera  129  and an interchangeable lens unit  130  including a vibration correction unit according to an embodiment of the present invention. 
     In FIG. 1, reference numeral  101  shows a camera-side control circuit responsible for the sequence of a camera  129  in its entirety. A sensor  111  detects vibration (shake) of the whole camera in a pitch direction and provides an output representing the vibration through a filter circuit  113  to an A/D converter  115  which in turn converts the output into digital data. The digital data is input to the camera-side control circuit  101 . Similarly, an output from a vibration sensor  112  (for detection in a yaw direction) is input to the A/D converter  115  through a filter circuit  114 . The digital data is input to the camera-side control circuit  101 . The vibration sensors  111 ,  112  and the filter circuits  113 ,  114  are formed of a vibration gyro as an angular velocity sensor and an integrator circuit as shown in FIG. 2, as an example of their specific configuration. 
     In FIG. 2, a vibration gyro  201  is resonance-driven by a driving circuit  203  and provides an output which is converted into a predetermined angular velocity output by a synchronous detection circuit  202  or the like. An output from the synchronous detection circuit  202  typically includes an unnecessary DC offset. The DC component is removed by a high-pass filter formed of a capacitor  205  and a resistor  206 , and only the remaining vibration signal is amplified by an amplification circuit formed of an operational amplifier  204  and resistors  207  and  208 . An output from the amplification circuit is then integrated by an integrating circuit formed of an operational amplifier  209 , resistors  210  and  211 , and a capacitor  212  for conversion into an output proportional to a vibration displacement. The integrated output is connected to the A/D converter  115  as described above. 
     Returning to FIG. 1, the camera-side control circuit  101  has therein a first timer  102  for setting the timing to read data from the A/D converter  115  at regular intervals to perform calculations for vibration correction, and a second timer  131  for providing the timing to transmit the result of the calculations for vibration correction to a lens-side control circuit  121  through a camera-side contact  103  for serial communication between the camera  129  and lens unit  130 . 
     On the other hand, light from an object is incident on a half-mirror type main mirror  104  through an image-taking optical system formed of an image-taking lens  125  and a vibration correcting lens  126 , which constitute an image-taking optical system. Light reflected by the main mirror  104  passes through a prism  108  which directs a part of the light to a viewfinder optical system, not shown, and the remaining part of the light to an AE sensor  110  for performing photometric measurements through a photometric lens unit  109 . The camera-side control circuit  101  performs exposure control such as calculations of a shutter speed and an F number based on luminance information from by the AE sensor  110 . 
     The light passing through the main mirror  104  is reflected by a sub mirror  105  and incident on an AF (autofocus) unit  106  includes a field lens and an AF sensor  107 . The camera-side control circuit  101  performs a distance measurement based on image information from the AF sensor  107 . 
     A shutter  116  (composed of a front curtain and a rear curtain) is subjected to timing control by a control signal from the camera-side control circuit  101  through a shutter driving circuit  117 . 
     The lens-side control circuit  121  is responsible for the sequence of a lens unit  130 . The result of the calculations for vibration correction transmitted from the camera  129  through serial communication is input to the lens-side control circuit  121  from a contact  122 . The lens-side control circuit  121  calculates a driving amount of the vibration correcting lens  126  based on the received data and the current position data of the vibration correcting lens  126  and outputs the result to a D/A converter  123 . The lens-side control circuit  121  has a third timer  132  for setting the timing to output the driving amount data for vibration correction to the D/A converter  123  such that the vibration correction unit is driven at regular intervals. The D/A converter  123  outputs an analog voltage proportional to the data input thereto. The output voltage is input to a vibration correction unit driving circuit  124  to drive the vibration correcting lens  126  in directions orthogonal to the optical axis of the image-taking lens  125 , indicated by arrows. 
     The specific configuration of the vibration correction unit is shown in FIG.  3 . 
     The vibration correction unit which corrects image vibration by the shifting of the vibration correcting lens  126  in x, y directions orthogonal to the optical axis. 
     In FIG. 3, reference numerals  301  and  302  show yokes as magnetic circuit units serving as actual driving source in the x, y axis directions. Reference numerals  303  and  304  show coils corresponding to the respective yokes  301  and  302 . Reference numeral  306  shows a support frame for supporting the vibration correcting lens  126  and the coils  303  and  304 . The coils  303  and  304  are supplied with an electric current from the vibration correction unit driving circuit  124  to drive the vibration correcting lens  126  in the x, y directions. 
     In turn, the movement of the vibration correcting lens  126  is detected in a noncontact manner by a combination of IREDs  307  and  308  movable together with the lens  126  and PSDs  313  and  314  attached onto a barrel portion  311  for holding the entire vibration correction unit. Reference numeral  309  shows a mechanical lock mechanism for mechanically holding the vibration correction lens  126  substantially at the center of the optical axis when vibration correction is stopped. Reference numeral  310  shows a charge pin, and  312  support balls serving as a stopper for regulating tilt directions of the vibration correcting lens  126 . 
     Returning again to FIG. 1, the current position of the vibration correcting lens  126  is detected by a vibration correction unit position detection circuit  127 . An output therefrom is read by the lens-side control circuit  121  through an A/D converter  128 . The camera  129  also has switches  118  (SW 1 ) and  119  (SW 2 ) associated with the operation of a release button (not shown), and a switch  120  (ISSW) for setting whether or not vibration correction is performed. 
     Next, description is made for how control is performed specifically with reference to flow charts shown in FIGS. 5 to  11 , a timing chart shown in FIG. 4, and the like. 
     FIGS.  5 (A) and  5 (B) show a main flow illustrating the control operations of the camera-side control circuit  101  associated with vibration correction. In FIGS.  5 (A) and  5 (B), lines with the same circled numerals connect with each other. In FIG.  5 (A), at step S 501 , it is determined whether or not the switch SW 1  ( 118 ) of the camera  129  is turned on in association with a release start operation. When it is turned on, the flow proceeds to steps S 502  and S 503  where a battery check circuit, not shown, determines whether or not supply voltage is sufficient for ensuring the operation of the whole camera  129 . When the result of this determination shows that the supply voltage is not sufficient, the flow proceeds to step S 504  to wait for turn-off of the switch SW 1 . When it is determined that the switch SW 1  is turned off, the flow returns to the start position. 
     When it is determined that the supply voltage is sufficient at step S 503  described above, the flow proceeds to step S 505  where it is determined whether or not the switch SWIS ( 120 ) is turned on. When the switch SWIS is turned off, it is determined that a vibration correction operation is not needed and the flow proceeds to step S 506  where an internal flag ISONL is reset to zero, and the flow immediately proceeds to step S 515 . On the other hand, when it is determined that the switch SWIS is turned on at step S 505  described above, it is also determined that an image-taking operation with vibration correction should be selected and the flow proceeds to step S 507  where a lock release command is transferred from the camera-side control circuit  101  to the lens-side control circuit  121  through a serial bus line. 
     FIG. 4 shows a timing chart showing the command communications. In FIG. 4, SCK represents a synchronous clock for serial communication, SDO serial data transferred from the camera  129  to the lens unit  130 , and SDI serial data transferred from the lens unit  130  to the camera  129  at the same time. 
     As in FIG. 4, when a command for mechanical lock release of at least one byte is transmitted to the lens unit  130  from the camera  129 , a BUSY signal indicating reception of the data is detected in SDI. This causes the camera-side control circuit  101  to determine at step S 508  in FIG.  5 (A) that the mechanical lock release operation of the vibration correcting lens  126  is completed (actually the completion of the mechanical lock release operation is delayed a little, but the release can be considered as completed when the command reception is completed in terms of the sequence), and the flow proceeds to step S 509 . 
     At step S 509 , a Y(yaw)/P(pitch) flag for determining whether interrupt processing is for the yaw or pitch direction is cleared. At subsequent step S 510 , the first timer  102  starts counting for an interrupt operation performed at predetermined intervals T1. At step S 511 , the control waits until the first timer counts to a predetermined time T2 (T2&lt;T1), then the flow proceeds to step S 512  where the second timer  131  starts counting for providing transmission timing of vibration data. The predetermined time T2 is a time period which is expected to be spent from the start of an interrupt operation (later described) by the first timer  102  to the transmission of vibration data in the interrupt operation. In other words, the second timer  131  counts the time elapsed since the predetermined timing (T2) at which the vibration data should be essentially transmitted. The second timer  131  is cleared at regular intervals T1 to repeat counting. 
     At the next step S 513 , the ISONL in the camera-side control circuit  101  is set to one for indicating a vibration correction operation status. At subsequent step S 514 , the interrupt operation of the timer is permitted. A photometric measurement operation is performed for measuring brightness of an object at step S 515 , and focus control is performed by driving an optical sensor and a focus lens, not shown, at next step S 516 . The focus control is continued until optimal focus is detected at step S 517 , and when optimal focus is detected, the flow proceeds to step S 518  where it is determined whether or not the switch SW 2  ( 119 ) of the camera  129  is turned on for release operation of the shutter  116 . 
     When turn-on of the switch SW 2  is detected at step S 518  described above, it is determined that a photographer starts an actual release operation and the flow proceeds to step S 519  where mirror-up operation is performed in the main mirror  104  of the camera  129  shown in FIG.  1 . 
     On the other hand, when it is determined that the switch SW 2  is not turned on yet at step S 518  described above, it is further determined that the photographer is performing a framing operation (considering the composition of an image) and the flow proceeds to step S 520 . When it is determined that the switch SW 1  is still turned on at step S 520 , the flow returns to step S 515  to repeat the aforementioned operations. However, when it is determined that the switch SW 1  is turned off at step S 520  described above, the camera-side control circuit  101  determines that the photographer ends the image taking with the camera  129 , and the flow proceeds to step S 521  where the value of the aforementioned flag ISONL is determined. 
     When the value of the ISONL is zero at step S 521 , it is determined that the vibration correction operation has not been started and the flow immediately returns to step S 501 . When the ISONL is one, it is determined that the vibration correction operation has been started and the flow proceeds to step S 522  where a lock set command is transmitted. The lock set command is transmitted from the camera-side control circuit  101  to the lens-side control circuit  121  as in the timing chart shown in FIG. 4, that is similar to the aforementioned lock release command (its data content is different). 
     It is determined whether or not the lock set of the vibration correcting lens  126  is completed at the next step S 523 . When the lock set completion is detected, an interrupt operation by the first timer  102  is inhibited at step S 524  to end a series of the operations. 
     Next, a description is made of the control function in an interrupt operation performed at regular intervals T1 counted by the first timer  102  with reference to a flow chart shown in FIG.  6 . 
     When the interrupt is started, it is determined first at step S 601  whether the present processing is for the yaw direction or the pitch direction based on the value of the Y/P flag. When the result of the determination shows that the Y/P flag is set to one, the flow proceeds to step S 610  to start processing for the pitch direction. Since steps S 610  to S 617  corresponding to the processing for the pitch direction are identical to a series of processing steps S 602  to S 609  for the yaw direction, next described, the description for the pitch direction is omitted. 
     When it is determined that the Y/P flag is zero at step S 601  described above, it is considered that processing for the yaw direction is performed in the present interrupt and the flow proceeds to step S 602 . At step S 602 , the A/D converter  115  starts to convert an output from the vibration sensor  112  in the yaw direction shown in FIG. 1 into digital data. When the completion of the conversion is detected at the next step S 603 , the flow proceeds to step S 604  where the result of the conversion is subjected to predetermined calculations. 
     The data conversion operation (S 604 ) is now described with reference to a data conversion subroutine shown in FIG.  10 . 
     In the operation of the data conversion subroutine, first, the content in an ADDATA register for storing the result of the A/D conversion is transferred to a general calculation register A in the camera-side control circuit  101  at step S 901 . At next step S 902 , data for correcting sensitivity of each vibration sensor is similarly transferred to a general calculation register B. Finally, at step S 903 , the data contents from the aforementioned two general calculation registers A and B are multiplied together and the result is set in a register C. 
     At subsequent step S 605 , the value of the second timer is then transferred to a register D. The second timer  131  counts the time elapsed since the predetermined timing (at which the first timer  102  counts to T2) at which vibration data should be essentially transmitted. Thus, the value transferred to the register D at this time corresponds to a delay time after the predetermined timing at which vibration data should be essentially transmitted. At step S 606 , the contents of the register D and the register C are transferred to a transmission data register, and an actual transmission operation is performed at step S 607 . 
     The actual transmission is performed as in the timing chart shown in FIG. 4 in the order of the command indicating that vibration information is transmitted (the command includes the flag for determining the yaw, pitch or the like), one byte of the content of the register D indicating the delay time after the timing at which vibration data should be essentially transmitted, and then serial data of at least one byte of the content of the register C corresponding to vibration data. 
     Returning to FIG. 6, when it is determined that the data transfer is completed at step S 608 , the Y/P flag is set to one at step S 609 . Finally, a timer interrupt flag associated with this operation is cleared to zero at step S 618  to complete the interrupt operation, and the flow returns to the main flow shown in FIGS.  5 (A) and  5 (B). 
     As described above, in the processing of the camera-side control circuit  101 , an interrupt occurs at regular intervals T1 to alternately perform the sampling of the outputs from the vibration sensors  111  and  112  for the pitch and yaw directions provided in the camera  129  and the calculation processing thereof, and the result (vibration data) and the delay time data of transmission timing are transmitted to the lens unit  130 . 
     Next, description of control operation of the lens-side control circuit  121  is made with reference to flow charts of FIGS. 7 to  9 . 
     FIG. 7 shows a main flow for the lens-side control circuit  121 . First, at steps S 701  and S 702 , correction calculation internal registers Cy, Cp for lens control are reset to 0H. At the next step S 703 , a flag LCK indicating lock set control is reset to zero. Similarly, at step S 704 , a flag ULCK indicating lock release control is reset to zero. At subsequent step S 705 , an interrupt operation of a serial interface is permitted for receiving the aforementioned data transmitted from the camera  129 . 
     At step S 706 , it is determined whether or not a command for prompting lock release is received in interrupt processing in serial interface communication, later described. When the flag ULCK is reset to zero, it is determined that the lock release command is not received and the flow proceeds to step S 709 . When the flag ULCK is set to one, it is determined that the lock release command is received and the flow proceeds to step S 707  to immediately perform a lock release operation of the vibration correcting lens  126 . In this event, the lens-side control circuit  121  provides a control signal with which an electric current is passed through a plunger  309  in the mechanical lock mechanism shown in FIG. 3 in a predetermined direction through a mechanical lock driver, not shown, to release the lock of the vibration correcting lens  126 . In addition, at step S 708 , the aforementioned flag ULCK is reset to zero. 
     Then, the flow proceeds to step S 709  where it is determined whether or not the flag LCK indicating the lock set is set to one. When the flag LCK is reset to zero, it is determined that a lock set command is not received and the flow returns to step S 706 . When the flag LCK is set to one, it is determined that the lock set command is received and the flow proceeds to step S 710  to immediately perform a lock set operation of the vibration correcting lens  126 . In this event, the lens-side control circuit  121  provides a control signal with which an electric current is passed through the plunger in the mechanical lock mechanism in the opposite direction to that for the aforementioned lock release to forcefully stop the movement of the vibration correcting lens  126  by a lever. Finally, at step S 711 , the flag LCK is reset to zero, and the flow returns to step S 706  to repeat the aforementioned operations. 
     Next, description is made for how the lens-side serial communication is processed with reference to FIGS.  8 (A),  8 (B) and  9 . In FIGS.  8 (A),  8 (B) and  9  lines with the same circled numerals connect with each other. 
     First, at step S 801 , a command as the communication content transmitted from the camera  129  is interpreted. At the next step S 802 , it is determined whether or not the communication content is the lock release command. When it is determined that it is the lock release command, the flow proceeds to step S 803  where the flag ULCK is set to one for prompting a lock release operation in the lens-side control circuit  121 , and the flow immediately proceeds to step S 843  where a flag for a serial interrupt is cleared to terminate the interrupt operation. Thus, in this event, the lock release operation is performed in the main flow operation in FIG. 7 as described above. 
     On the other hand, when it is determined that the command is not the lock release command at step S 802 , the flow proceeds to step S 804 . At step S 804 , it is determined whether it is the lock set command. When it is determined that it is the lock set command, the flag LCK is set to one for prompting the lock set operation in the lens-side control circuit  121  at the next step S 805 . The flow proceeds to step S 843  in FIG. 9 to terminate the interrupt operation similarly to when the lock release command is received. 
     When it is determined that the command is not the lock set command at step S 804 , the flow proceeds to step S 806 . At step S 806 , it is determined whether or not it is vibration data in the yaw direction. When it is determined that the received command is not a command for receiving yaw data, the flow proceeds to step S 824  in FIG.  9 . At step S 824 , it is determined whether or not it is vibration data in the pitch direction. When it is determined that the received command is not coincident with a command for receiving pitch data at step S 824 , normal lens communication processing (for example, for control of the focus lens and a diaphragm [not shown]) is performed, and after that operation is completed, the flow proceeds to step S 843  to terminate the interrupt operation. 
     When it is determined that the received command is coincident with the command for receiving pitch data at step S 824 , the flow proceeds to step S 826  to start processing for the pitch direction, that is, the processing from steps S 826  to S 842 . Since the series of the processing for the pitch direction is identical to a series of the processing for the yaw direction of steps S 807  to S 823  in FIGS.  8 (A) and  8 (B), next described, the description for the pitch direction is omitted. 
     When it is determined that the received command is coincident with the command for receiving yaw data at step S 806  in FIG. 8, the content of serial data in the form as shown in the timing chart of FIG. 4 is set such that a transmission delay time (delay time data) is set in a register Td in the lens-side control circuit  121  and vibration data (received yaw data) is set in a register Sy at steps S 807  and S 808 , respectively. 
     At the next step S 809 , the value of Td is compared with a predetermined value T4. T4 represents a time period required for a series of calculation processing from steps S 810  to S 815 , later described. When the value of Td is smaller than T4, the vibration data is transmitted from the camera  129  after a slight delay and it is assumed that there is enough time to perform the series of calculation processing for driving of the vibration correction unit performed at regular intervals. Then, the flow proceeds to step S 810  where the A/D converter  128  starts to convert the output from the vibration correction unit position detecting circuit  127  (formed of the IREDs, PSDs and processing circuit) shown in FIG. 1 to digital data. At next step S 811 , it is determined whether or not the A/D conversion operation is completed. When it is determined that the A/D conversion operation is completed, the flow proceeds to step S 812 . At step S 812 , the result is transferred to a register Ty in the lens-side general control circuit  121 . At next step S 813 , feedback calculations are performed for the yaw correction system such that the content of the register Sy for storing the received vibration data is coincident with the content of the register Ty for storing the data corresponding to the output representing the position of the vibration correction unit. How the feed back calculations are performed is described with reference to the flow chart of FIG.  11 . 
     In FIG. 11, first, at step S 1001 , the difference between the contents of the aforementioned register Sy (register Sp in the case of the pitch direction) and the register Ty (register Tp in the pitch direction) is set again to the register Sy. At next step S 1002 , the result is multiplied by predetermined data LPG for determining a loop gain of the feed back control of the vibration correction unit, and the result is set again to the register Sy. Subsequent steps S 1003  to S 1005  are operations for performing phase compensation calculations (in this event, first-order phase lead compensation) of this system for vibration correction. Values of coefficients B1, A0, and A1 used in the calculations are previously set as predetermined data by the known S-Z transform. 
     Specifically, at step S 1003 , the product of the predetermined coefficient data B1 and the content of the calculation register Cy (Cp in the case of the pitch direction, and these registers store values determined at the preceding sampling) is subtracted from the content of the register Sy, and the result is set to a register Dy (Dp). At next step S 1004 , the product of the predetermined coefficient data A1 and the content of the register Cy is added to the product of the predetermined coefficient A0 and the content of the register Dy as a multiply and accumulate operation, and the final result is set to a register Oy (Op). Finally, at step S 1005 , the value of the register Dy is transferred to the register Cy for the next set of calculations, and the feedback calculations of the vibration correction unit are ended. 
     Returning to FIG.  8 (B), after the aforementioned feedback calculations are completed at step S 813 , the flow proceeds to step S 814 . At step S 814 , the control waits for the third timer  132  in the lens-side control circuit  121  counting to a predetermined time T3. The time T3 corresponds to control intervals for the vibration correction unit. 
     When the value of the third timer  132  reaches T3, the flow proceeds to step S 815 . At step S 815 , the value of the register Oy, which is the result of the aforementioned feedback calculations, is transferred to the D/A converter  123  in FIG. 1 as DADATA. This causes electric current corresponding to the output value to be applied to the vibration correction unit (coils  303  and  304 ) through the driving circuit  124 , thereby driving the vibration correcting lens  126  in the yaw direction based on the vibration sensor  112  output in the yaw direction. At subsequent step S 816 , the third timer  132  is reset to start counting in preparation for the next driving control of the vibration correction unit, and then the flow proceeds to step S 843  to terminate the interrupt operation. 
     On the other hand, when Td is larger than T4 at step S 809 , the flow proceeds to step S 817  since a series of processing such as feedback calculations cannot be completed in time for the timing for the next driving of the vibration correction unit. At step S 817 , the control waits until the third timer  132  counts to T3 to reach the timing for driving the vibration correction unit. Then, at step S 818 , the value of the register Oy which sets the driving amount of the vibration correction unit based on the previously received vibration data (or the average of a plurality of already received vibration data values or the like may be used) is transferred to the D/A converter  123  as DADATA to drive the vibration correction unit. When the control is ended, the flow proceeds to step S 819  where the third timer  132  is reset, and then the same calculation processing as that in steps S 810  to S 813  described above is performed at step S 820  to S 823 , and the content of the register Oy is again set. Finally, at step S 843 , the interrupt flag is cleared to end the interrupt processing. 
     Up to this point, the embodiment has been described. 
     According to the aforementioned embodiment, when a temporary delay occurs in transmission of vibration data which essentially should be performed at regular intervals from the camera  129  to the lens unit  130 , due to some reason in terms of the balance between the transmission and another operation, the lens unit  130 , for example, can support the delay (at step S 818  in FIG.  8 (B) and step S 837  in FIG. 9, the previously received vibration data is used to drive the vibration correction unit) by communicating the delay time data of transmission together with the vibration data (at steps S 605  and  613  in FIG.  6 ). Thus, deteriorated accuracy of the control for vibration correction can be prevented. 
     The time data transmitted together with the vibration data may be data indicating the point in time to be transmitted, rather than the data indicating the delay time period. In this event, a delay time after the predetermined timing at which the data should be essentially transmitted is calculated from the relationship between the current data on the point in time and the previous data on the point in time. 
     In addition, while the present embodiment has been described for the vibration gyro used as the vibration sensor, the means for detecting vibrations is not limited to a mechanical sensor such as a gyro, and may detect vibrations from an image fetched by an area sensor or the like. 
     As described above, according to the present invention, a camera system capable of preventing deteriorated accuracy of vibration correction can be provided even when vibration data cannot be transmitted to the optical apparatus at regular intervals. 
     In the aforementioned embodiment, the description has been made about a camera system comprising a camera and an interchangeable lens unit including a vibration correction unit. The present invention, however, can adapt to a camera system comprising a camera integrally having an image-taking lens and a vibration correction unit being attachable to the image-taking lens. In addition, the present invention can adapt to a vibration correction unit being attachable to an interchangeable lens unit. 
     While preferred embodiment has been described, it is to be understood that modification and variation of the present invention may be made without departing from the sprit or scope of the following claims.

Technology Classification (CPC): 7