Abstract:
This invention relates to a system for communicating speed data from a camera to a lens unit to drive the lens unit. Even if speed data changes stepwise, a change amount of the driving speed can be changed within a predetermined range for each stepwise change of the speed data in a whole driving speed change range. An optical apparatus having drive circuit for receiving speed data communicated from the unit which sends the speed data representing speed information and controlling, on the basis of the information, the speed of a moving member which moves within a predetermined range includes a determination circuit for determining a driving speed on the basis of position data, the speed data, and a value representing an actual range of the predetermined range, the position data defining the predetermined range as a predetermined number different from a value indicating the actual range and representing the predetermined number as another value in accordance with a time required to move the moving member within the predetermined range.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an optical unit such as an image sensing lens used in television image sensing. 
   2. Related Background Art 
   A conventional broadcasting television camera system performs communication using an analog signal via a camera-lens interface. For example, voltages for determining the position of a focus lens or iris and the speed of a zoom lens are designated for a lens to control a lens system. Voltages representing the positions of a focus lens, zoom lens, and iris are applied to the camera side to transmit the lens information to the camera. 
   A lens uses an analog servo control system by constructing a feedback system using a potentiometer as a position sensor. 
   The types, number, and precision of analog signals are limited, and a serial interface tends to be used as a camera-lens communication function. 
   In the above control device, no normalization is performed in transmitting a data, such as the speed data, between the camera and lens, resulting in poor controllability. 
   SUMMARY OF THE INVENTION 
   One aspect of the application is to provide an optical apparatus having a drive circuit for receiving speed data communicated from a unit which sends the speed data representing speed information and controlling, on the basis of the information, the speed of a moving member which moves within a predetermined range, comprising a determination circuit for determining a driving speed on the basis of position data, the speed data, and a value representing an actual range of the predetermined range, the position data defining the predetermined range as a predetermined number different from a value indicating the actual range and representing the predetermined number as another value in accordance with a time required to move the moving member within the predetermined range so as to provide an appropriate driving speed. 
   One aspect of the application is to provide an optical apparatus having a drive circuit for receiving speed data communicated from a unit which sends the speed data representing speed information and controlling, on the basis of the information, the speed of a moving member which moves within a predetermined range, comprising a determination circuit for determining a driving speed on the basis of position data and the speed data, the position data representing the predetermined range as a predetermined number and the number as another value in accordance with a time required to move the moving member within the predetermined range so as to provide an appropriate driving speed. 
   One aspect of the application is to provide an optical unit having a moving member moving within a predetermined range and a drive circuit for controlling a speed of the moving member, wherein the speed of the moving member is determined on the basis of position data representing the predetermined range as a predetermined number of steps and speed data representing a moving amount per unit time as the predetermined number of steps. 
   The above and other objects, features, and advantages of the present invention will be apparent from the following detailed description of the preferred embodiment in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram showing the system configuration of the first embodiment of the present invention; 
       FIG. 2  is a block diagram showing an encoder pulse output mechanism in  FIG. 1 ; 
       FIG. 3  is a view for explaining the output pulse number of an encoder in  FIG. 1 ; 
       FIG. 4  is a view for explaining the number of normalization steps in the first embodiment; 
       FIG. 5  is a view showing the lens moving direction of the first embodiment; 
       FIG. 6  is a pulse number table 1 of the first embodiment; 
       FIG. 7  is a pulse number table 2 of the first embodiment; 
       FIGS. 8A and 8B  are waveform charts in the CW and CCW directions, respectively; 
       FIG. 9  is a normalized speed command table of the first embodiment; 
       FIG. 10  is another normalized speed command table of the first embodiment; 
       FIG. 11  is still another normalized speed command table of the first embodiment; 
       FIG. 12  is a table representing the whole range movement time with respect to the normalized speed command of the first embodiment; and 
       FIG. 13  is a view for explaining the normalized positions and speed commands of the first embodiment. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   (First Embodiment) 
     FIG. 1  is a block diagram showing an optical system according to the first embodiment of the present invention. The optical system comprises a lens unit  101  for image sensing and camera unit  121  for sensing an image through the lens unit  101 . 
   A controller (to be referred to as an aCPU hereinafter)  102  manages the lens unit and controls the servo system. A driver  103  drives a motor  104 . An optical lens  106  is connected to the motor  104 . An encoder  107  detects the position of the optical lens  106  and outputs the pulse number corresponding to the moving amount of the lens. A counter  108  counts outputs (pulses) from the encoder  107 . 
   A timer  112  and the counter  108  are connected to the aCPU  102 . The aCPU  102  uses the values of the counter  108  and timer  112  to detect the position and speed of the optical lens  106 . 
   A manual operation portion  105  manually operates the optical lens  106 . A switch (to be referred to as an R/L-SW hereinafter)  110  selects control of the lens unit  101  in the remote or local mode. A demand  131  is connected to an A/D converter  111  in the lens unit  101 . The A/D converter  111  A/D-converts a command from the demand  131 . A demand command value for controlling the optical lens  106  can be input to the aCPU  102 . 
   A camera controller (to be referred to as a bCPU hereinafter)  122  is mounted in the camera unit  121  and performs serial communication  141  with the aCPU  102  of the lens unit  101 . 
   The remote and local modes selectively set by the R/L-SW  110  will be described below. The remote mode is to control the optical lens  106  in accordance with a control command from the bCPU  122  in the camera unit  121 . The local mode is to control the optical lens  106  by selecting a control command from the demand  131 . 
   The relationship between the moving direction of the optical lens  106  and the count value of the counter  108  will be described with reference to FIG.  5 . Assume that the optical lens  106  is a focus lens. 
   If the count value of the counter  108  at the infinity (INF) end  210  of the focus lens is defined as 0, the count value of the counter  108  at the minimum object distance (MOD) end  211  is 20,000. 
   When the focus lens rotates in the clockwise (CW) direction, the focus lens moves to the MOD end  211  direction to increment the counter  108 . When the focus lens rotates in the counterclockwise (CCW) direction, the focus lens moves to the INF end  210  direction to decrement the counter  108 . 
   During which the focus lens is moving in the MOD end  211  direction, the speed of the focus lens takes a positive value. During which the focus lens is moving in the INF end  210  direction, the speed of the focus lens takes a negative value. 
   The encoder pulse output mechanism for detecting the position and speed of the focus lens will be described with reference to FIG.  2 . 
   The diameter of a C gear  202  mounted on the drive motor  104  is φMotor [mm], and the diameter of a B gear  203  meshed with the C gear  202  is φFocus [mm]. A focus lens  207  can move from the INF end (infinity)  210  to the MOD (minimum object distance) end  211  by B gear  203 . 
   The B gear  203  is meshed with an A gear  204  mounted on the encoder  107 , and a pulse output from the encoder  107  is input to the counter  108 . The diameter of the A gear  204  is φEnc [mm], and the output pulse per rotation of the encoder  107  is PPEnc [P/R]. The focus lens  207  can be moved from the INF end  210  to the MOD end  211  by using the manual operation portion  105 . 
   A servo/manual mode selection SW (not shown) is arranged. In the servo mode, the focus lens  207  is driven by the motor  104 . In the manual mode, the focus lens  207  can be operated by using the manual operation portion  105 . 
   A clutch (not shown) is connected to the motor  104 . In the manual mode, the encoder  107  rotates in accordance with movement of the focus lens  207 . However, the driving force of the motor  104  is not transmitted to the focus lens  207  by the clutch. 
   In the above arrangement, the counter  108  represents the following count value PPRot per rotation of the motor  104 :
 
 PPRot= φMotor/φ Enc×PPEnc   (1) 
 
   If the rotation number of the motor  104  for moving the focus lens  207  from the INF end  210  to the MOD end  211  is defined as NRot, an output pulse number PPTotal of the encoder  107 , which is generated when the focus lens  207  moves from the INF end  210  to the MOD end  211 , is given as follows:
 
 PPTotal=PPRot×NRot   (2) 
 
   The count of the counter  108  which counts the output pulses from the encoder  107  upon moving the focus lens  207  from the INF end  210  to the MOD end  211  is calculated using equations (1) and (2) under the following conditions. 
   [Conditions] 
   Output Pulse Number per Rotation of Encoder  107 
         PPEnc=2500 [P/R]       

   Diameter of A Gear Mounted on Encoder  107 
         φEnc=10 [mm]       

   Diameter of C Gear Mounted on Motor  104 
         φMotor=20 [mm]       

   Rotation Number of Motor  104  for Moving Focus Lens  207  from INF End  210  to MOD End  211 
         100 [rotations].       

   At this time, when the count value of the counter  108  at the INF end  210  is set to “0”, the count value PPTotal of the counter  108  at the MOD end  211  is given as follows:
 
 PPTotal= 20/10×2500×100=500000[Pluses]
 
   Similarly, the calculation examples of the count values PPTotal upon changes in PPEnc, φEnc, φMotor, and NRot are shown in FIG.  6 . 
   An output from the encoder  107  is generally obtained by a two-phase output scheme for generating A- and B-phase outputs having a phase difference of 90°. When the encoder  107  rotates in the CW direction, the A phase advances from the B phase by 90°, as shown in FIG.  8 A. When the encoder  107  rotates in the CCW direction, the A phase delays from the B phase by 90°, as shown in FIG.  8 B. 
   To cope with this, the counter  108  detects the edges of the A and B phases and counts the A- and B-phase pulses. As a result, the counter  108  counts 4-fold values. When the A phase advances from the B phase, the counter  108  increments the value. When the A phase delays from the B phase, the counter  108  decrements the value. The 4-fold value count result is shown in FIG.  7 . 
   As described above, the count value PPTotal of the counter  108  in the movable range of the focus lens  207  between the INF end  210  and MOD end  211  is influenced by the rotation number NRot of the motor  104  depending on the movable range of the focus lens, the diameter φMotor of the C gear  202  mounted on the motor  104 , the diameter φEnc of the A gear mounted on the encoder  107 , and the output pulse number PPEnc per rotation of the encoder  107 . The count value PPTotal has a considerably wide range. 
   The pattern of the count value of the counter  108  at the MOD end  211 , as shown in  FIG. 3 , when the INF end  210  is defined as a reference value “0” (count value of the counter  108 ) for the focus lens  207  will be described below. 
   For example, when the count values of the counter  108  at the MOD end  211  are given as 10,000, 500,000, and 35,000,000, the numbers of bytes required for these count values are given as follows:
         (1) 2 bytes for 10,000 [pulses]   (2) 3 bytes for 500,000 [pulses]   (3) 4 bytes for 35,000,000 [pulses].       

   This indicates that data changes depending on the types of lens units  101  when the bCPU  122  of the camera unit  121  designates the position of the focus lens  207  using serial communication  141 . For example, when the bCPU  122  designates via the serial communication  141  that the focus lens  207  is moved to a position of 5,000, the aCPU  102  of the lens unit  101  moves the lens unit  101  as follows:
         5000/10000=0.5 (=50 [%]) for (1); the focus lens  207  is moved to the center between the INF end  210  and MOD end  211 .   5000/500,000=0.01=(=1[%]) for (2); the focus lens  207  is moved to a position near the INF end  210 .       

   5000/350,00000−0.00014(=0.014 [%]) for (3); the focus lens  207  is rarely moved from the INF end  210 . 
   As can be apparent from the above result, the bCPU  122  of the camera unit  121  must know the resolution (pulse number of the whole movable range from the INF end  210  to the MOD end  211 ) of the effective movable range of the focus lens  207  of the lens unit  101 . The bCPU  122  obtains the resolution by information exchange via the serial communication  141  when initialization of the camera unit  121  and lens unit  101  is complete. A description will be made for, e.g., (2). When the bCPU  122  of the camera unit  121  requests position resolution information of the focus lens  101  to the aCPU  102  of the lens unit  101  via the serial communication  141 , the aCPU  102  transfers the positions of the INF end  210  and MOD end  211  as “0” and “500,000”, respectively, to the bCPU  122  of the camera unit  121  via the serial communication  141 . 
   As can be apparent from (1) to (3), the numbers of bytes of position information of the focus lens  207  are different from each other. This indicates that the data length necessary for arithmetic operation of the bCPU  122  of the camera unit  121  changes depending on the types of lens units  101 . 
   Assume that the bCPU  122  of the camera unit  121  is a 16-bit microcomputer. In this case, arithmetic processing for (1) can be performed with a 2-byte (16 bits, int) length. Arithmetic processing for (2) requires a 4-byte (32 bits, long) length. Arithmetic processing for (3) must be performed with the floating point (float). Arithmetic processing often requires high speed, processing must be performed with the fixed decimal point as much as possible. Arithmetic processing is desirably possible with int (16-bit data length for a 16-bit microcomputer; 32-bit data length for a 32-bit microcomputer). 
   As shown in  FIG. 4 , the resolutions between the INF end  210  and MOD end  211  are normalized, and fixed data is always used to give a position command between the lens unit  101  and camera unit  121  via the serial communication  141 . 
   This makes it possible for the camera unit  121  not to consider the resolution of the focus lens  207  depending on the types of lens units  101 . 
   The position resolution required for the focus lens  207  will be described below. The resolution calculated by the MTF and sensitivity is said to be about {fraction (1/5000)} for NTSC and about {fraction (1/20,000)} for HD. 
   Assume that the whole range, INF end  210 , and MOD end  211  are given by 30,000, “0”, and “30,000”, respectively. A sufficient resolution can be obtained for the focus lens  207 . 
   When the position command for the focus lens  207  is given as “15,000”, the aCPU  102  of the lens unit  101  moves the focus lens  207  to positions having the following ratios using the above normalized data:
         (10000×15000/30000)/10000=0.5 for (1)   (500000×15000/30000)/500000=0.5 for (2)   (35000000×15000/30000)/35000000=0.5 for (3).       

   The aCPU  102  can move the focus lens  207  to the middle position between the INF end  210  and MOD end  211  regardless of the types of lens units  101  (pulse number from the INF end  210  to MOD end  211  of the focus lens  207 ). 
   The normalized position information may be exchanged using the serial communication  141  after initialization of the lens unit  101  and camera unit  121  is complete. Alternatively, the normalized position information may be predetermined by information communication format between the lens unit  101  and camera unit  121 . 
   The following equation is used to calculate a command position PPFocus Cmd of the focus lens  207  in the lens unit  101  in accordance with the normalized position command:
 
 PPFocus Cmd=PPInfMod×NorFocus Cmd/NorInfMod   (3) 
         where NorInfMod is the whole range normalized position between the INF and MOD ends, PPInfMod is the effective pulse number between the INF and MOD ends, and NorFocus Cmd is the normalization position command.       

   The following equation is used to obtain the normalized position information NorFocusInf from the current position PPFocusInf of the focus lens  207 :
 
 NorFocusInf=NorInfMod×PPFocusInf/PPInfMod   (4) 
 
   If this normalized position information NorFocusInf is transferred from the lens unit  101  to the camera unit  121  using the serial communication  141 , the camera unit  121  can detect the position of the focus lens  207  regardless of the types of lens units  101 . 
   A speed command will be described with reference to  FIG. 9. A  system is generally incorporated in a video camera using a signal synchronized with image data for performing image processing. In this case, a vertical synchronizing signal (V synchronizing signal) as one frame of an image signal is used. 
   The V synchronizing signal has a period of {fraction (1/60)} [sec] for NTSC, {fraction (1/50)} [sec] for PAL, and {fraction (1/60)} [sec] for HD. The speed command and speed information are preferably the speed data of the V synchronizing unit. A case using the speed data of the V synchronizing unit will be described below. 
   The whole range normalized position, i.e., normalized step number of movable range for lens, for speed is given as “30,000”. The absolute value of the speed command of the minimum unit is “one step/V synchronizing unit”. The next speed is “two steps/V synchronizing unit”. At this time, a change in minimum speed is “+one step/V synchronizing unit”. If the current speed command is given as “N steps/V synchronizing unit”, the minimum speed command changing ratio is (1/N)×100 [t]. The table of this result is shown in FIG.  9 . 
   As can be apparent from this table, when the speed command of the V synchronizing unit falls within the range of about 1 to 10, the speed changing ratio is considerably large. When the speed command is about 25 or more, the changing ratio falls within the range of 5 [%] or less. 
   When the speed command becomes about 1,600, the speed changing ratio rarely changes (the changing ratio is small). Values required as speeds of TV lenses generally fall within the whole range movement time range of 0.3 [sec] to 300 [sec], and have a value 1,000 times as the dynamic range. The whole range movement time can be calculated by the following equation:
 
(Whole Range Movement Time [sec])=(Whole Range Normalized Position for Speed)/(Normalized Speed Command (Step Number))×(V Synchronizing Unit) [sec]  (5) 
 
   As described above, the speed is defined using the whole range normalized position for speed (range information defining the movable range as the predetermined range regardless of the actual movable range). Even if a lens having another movable range is mounted on a camera, processing can be performed using the whole range movement time as a constant time if a speed command from the camera is kept unchanged. 
   As described above, processing can be performed using the whole range movement time as the constant value when the speed command is kept unchanged. When the minimum unit of the speed command changes, a large speed command value has a speed changing ratio different from that of a small speed command value. 
   More specifically, in control using equation (5), a sufficient speed resolution is obtained on the high speed movement side (the speed command resolution is 0.06 [%] in the whole range movement time of about 5 [sec]). The practical range on the low speed movement side has the whole range movement time of about 20 sec (speed resolution of about 4 [%]). That is, a changing ratio becomes 50 [%] in the whole range movement time of 250 [sec]. The changing ratio is too large in the practical range. The practical use limits the speed changing ratio of 5 [%] or less because the speed changing ratio exceeding this range is too large to use. 
     FIG. 10  shows a case in which the whole range normalized position for speed is set to “500,000”. In this case, the speed command becomes about 25 [steps/V synchronizing unit] near the whole range movement time of about 300 [sec]. Therefore, the speed changing ratio can fall within the range of 5 [t] or less. 
   Since the speed command on the high speed movement side (whole range movement time of 0.3 [sec]) is 27,400 [steps/V synchronizing unit] or less, the corresponding speed command falls within the 16-bit range from the high speed to the low speed. 
   When the whole range normalized position for speed is set to “500,000”, the speed changing ratio on the high speed movement side is very small, and a command for commanding high speed movement is hard to process. The list of speed commands for the whole range normalized position of “1000” for high speed movement is shown in FIG.  11 . As can be apparent from this table, the speed changing ratio on the high speed movement (whole range movement time of 0.5 [sec] or less) side is about 2 to 3 [%], and the high speed movement speed commands can be easily processed. 
   Similarly, it is possible to obtain a whole range normalized position for middle speeds. 
   Differences occurring when the same normalized speed command is given to high, middle, and low speed movement speed commands will be described with reference to FIG.  12 . 
   The whole range movement times are calculated under the assumptions that the high, middle, and low speed movement speed commands take “1,000”, “30,000”, and “500,000” as whole range normalized positions, respectively. Since a speed changing ratio that facilitates speed operation when applying a speed command is considered to be about 2 [%], the normalized speed command is defined as 50 (steps/V synchronizing unit={fraction (1/60)} [sec]) corresponding to the speed changing ratio of 2 [%]. 
   The whole range movement times for the high, middle, and low speed movement speed commands are 0.33 [sec], 10.00 [sec], and 166.67 [sec], respectively. That is, the lens can be driven selecting a high, middle, and low speed movement speed command in consideration of the speed changing ratio at which easy operation is allowed. A speed command is given in consideration of the speed resolution, thereby allowing smooth lens control. 
   The format of the command will be described with reference to FIG.  13 . As a scheme for sending a command from the camera unit  121  to the lens unit  101 , a format made up of an 8-bit head portion and 16-bit data portion is employed. 
   In this case, the head portion is assigned for a movement command of lens  106  and the data portion is assigned for a command information. For example, the movement command A1H is defined as a normalized position command. In this case, B1H (corresponding to 500,000 described above and representing low speed movement whole range normalized position), B2H (corresponding to 30,000 described above and representing middle speed movement whole range normalized position), and B3H (corresponding to 1000 described above and representing the high speed movement whole range normalized position) are assigned to low, middle, and high speed whole range normalized speed commands, respectively. 
   The data portion is assigned for the normalized position command which contains position information representing a position at which the lens  106  is to be stopped. 
   The data portion in case of the normalized speed command contains a value determined in consideration of the direction of the movement step number of the V synchronizing unit. In this case, the direction takes a positive (+) value when the focus lens  207  is moved toward the MOD end  211  and a negative (−) value when the lens  207  is moved toward the INF end  210 . 
   The normalized speed command can take values falling within the range of “−2,000 [steps/V synchronizing unit]” to “+2,000 [steps/V synchronizing unit]” at the speed command whole range normalized position of 30,000 and the maximum speed data of the whole range movement time of about 0.3 [sec]. 
   The speed command whole range normalized position may be predetermined for a speed command (head portion) or may be determined by initial communication between the lens unit  101  and camera unit  121 . 
   More specifically, when a speed command is sent for the whole range normalized position from the camera unit to the lens unit, predetermined data corresponding to the speed commands are stored in the lens unit as “500,000” for low speed movement and “30,000” for middle speed movement. Data may be selected in accordance with the communicated command. Alternatively, data may be paired with a command and communicated from the camera unit to the lens unit. 
   Speed control of the lens to which the normalized speed command (whole range normalized position) and normalized speed command are communicated as described above will be described below. 
   For example, when the lens is to be driven at high speed, “1000” and “50” are given as the whole range normalized position and the normalized speed command, respectively. These data are communicated from the camera unit to the lens unit, and the speed of the lens unit is controlled under the above conditions. In this case, if the original whole range movement distance of the lens unit is X (fixed), since the whole range normalized position is “1,000” and the movement time per step is {fraction (1/60)} sec, the driving speed is represented by equation X/1000×60×50. 
   The speed of the lens drive (motor) is defined as X/[whole range normalized position]×[normalized speed command]×[V synchronizing unit], in accordance with the above normalized speed command and whole range normalized position. The lens side performs the above calculation in accordance with the whole range normalized position and normalized speed command from the camera unit, thereby determining the motor speed and performing speed control. 
   The normalized speed command preferably has a value range so that the speed changing ratio falls within the range of 2 to 3%. 
   A speed command as a command sent from the camera unit  121  to the lens unit  101  has been described with reference to  FIGS. 9  to  13 . Speed information of the lens  106  of the lens unit  101  may be similarly defined as described above and sent to the camera unit  121 . 
   The “V synchronizing unit” has been used as the time-axis unit of the speed command or speed information. However, any other unit may be used. 
   The focus lens has been described as the lens  106  of the lens unit  101 . However, the present invention is also applicable to any other optical system such as a zoom lens or iris. 
   The present invention is also applicable to an accessory except the camera unit. The encoder is used as a means for detecting the lens position. However, a combination of a potentiometer and A/D converter may be used. The position command normalized positions and speed command normalized positions are exemplified by values “30,000”, “50,000”, and “1,000”. The values are not limited to these specific values, but can be replaced with other values. Serial communication is used in communication between the lens unit and camera unit. However, parallel communication can be used. 
   Communication using the position command normalized position and speed command normalized position is not limited to one between the lens unit  101  and camera unit  121 . A command from the demand  131  serving as an accessory is input to the aCPU  102  of the lens unit  101  via the A/D converter  111 . However, when a CPU is mounted in the demand  131  and has the same communication function as in the camera unit, it is possible to apply the above communication by normalizing the lens position and speed. 
   Communication upon normalizing the position and speed information of the lens  106  is also applicable to communication between the lens unit  101  and another system (including an accessory) like the camera unit  121 . 
   As has been described above, according to the present invention, for example, in a combination of an image sensing lens and a camera or accessory, or in an image sensing lens itself, the speed of a moving member such as an optical system can be controlled using predetermined arithmetic processing regardless of the types of systems for driving lens systems.