Abstract:
An image input apparatus has a pan head for mounting an image pickup device thereon and for changing the image pickup direction of the image pickup device. The image pickup device has an engaging device, and control terminals capable of transmitting specification information about an operation of the pan head from the image pickup device to the pan head. The pan head has a holding device to be engaged with the engaging device so as to interchangeably hold the image pickup device, identifying terminals capable of receiving the specification information when the image pickup device is held by the holding device, and a selection circuit for selecting an operation of the pan head corresponding to the held image pickup device based on the received specification information.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a pan head for turning a pedestal (which has a mechanism for holding an image pickup device) in at least one of the horizontal and vertical directions. The present invention also relates to an image pickup device held by such a pan head, and to an image input apparatus provided with both the pan head and the image pickup device. 
     2. Description of the Related Art 
     In recent years, a video camera which generates video signals corresponding to a subject has been widely used as an image input apparatus for a computer, and a combination system made up of this video camera and a computer (for example, a personal computer and a work station) is proceeding toward practical utilization in electronic mail for images, a videoconference system, and the like. 
     In these electronic image mail and video conference systems, a monitoring camera developed for monitoring, an image input apparatus equipped with a combination of a monitoring camera with a remote controlled lens and a remote controlled pan head for holding the monitoring camera, and the like are used. 
     For example, in a videoconference system using only a monitoring camera, the monitoring camera is fixed on the ceiling, the wall or the like so as to capture a predetermined image taking area. However, since the image taking area of the monitoring camera is thus predetermined, it is impossible to adapt to various circumstances, for example, to concentrate image taking on an arbitrary speaker, by changing the image taking area during a videoconference, which thus results in a failure to sufficiently deliver functionality with respect to the videoconference. 
     On the other hand, in a videoconference system using an image input apparatus equipped with a combination of a monitoring camera with a remote controlled lens and a remote controlled pan head for holding the monitoring camera, the pan head with the monitoring camera mounted thereon is fixed on the ceiling, the wall or the like, and the lens and the pan head are driven by remote control as occasion demands. Since this method can change the image taking area and direction by remote control, it is possible to readily concentrate image taking on an arbitrary speaker, or to take an image of the whole or part of a conference room, and therefore, to sufficiently deliver functionality required for the videoconference. Furthermore, a camera with a lens having an appropriate focal length can be mounted on the pan head, which allows the choice of a video camera with reference to the environment such as a conference room. 
     The above-mentioned image input apparatus is equipped with a pan head for interchangeably mounting a video camera thereon to choose a video camera suited to the environment. However, since the driving force of a pedestal in the pan head is set such as to cope with the heaviest video camera to be mounted thereon, a large pan head, which is high in cost, is needed. Therefore, it is difficult to obtain a low-cost image input apparatus. 
     Furthermore, it is necessary to change the control on the pan head in accordance with a video camera at every replacement of the video camera, and this change is troublesome. 
     In order to lower the cost of the pan head and to simplify the change of control on the pan head, a videoconference camera combining an image pickup device and a pan head has been developed and is nearing practical use. However, since the image pickup device and the pan head are combined in the videoconference camera, it is impossible to choose the camera with reference to the environment, such as a conference room. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an image input apparatus which solves the above problems, achieves high general versatility, reduces cost, and simplifies the change of operation control on a pan head. 
     In order to achieve the above object, according to an aspect of the present invention, there is provided an image input apparatus having a pan head for mounting an image pickup device thereon and for changing the image pickup direction (or orientation) of said image pickup device, wherein the image pickup device comprises an engaging portion and a transmission means capable of transmitting specification information about an operation of the pan head from the image pickup device to the pan head, and the pan head comprises a holding portion to be engaged with the engaging portion so as to interchangeably hold the image pickup device, a receiving means capable of receiving the specification information when the image pickup device is held by the holding portion, and a selection means for selecting an operation of the pan head corresponding to the held image pickup device based on the specification information received. 
     According to another aspect of the present invention, there is provided a pan head for mounting an image pickup device thereon and for changing the image pickup direction of the image pickup device, the pan head comprising a holding means for interchangeably holding the image pickup device, and a selection means for selecting an operation of the pan head corresponding to the image pickup device when the image pickup device is mounted on the holding means. 
     According to a further aspect of the present invention, there is provided an image pickup device mountable on a pan head capable of changing the image pickup direction of the image pickup device, the image pickup device comprising an engaging portion to be engaged with a holding portion provided in the pan head, and a transmission means capable of transmitting information about an operation of the pan head from the image pickup device to the pan head. 
     These and other objects, features and advantages of the present invention will become more apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram showing the configuration of an embodiment of an image input apparatus according to the present invention; 
     FIG. 2 is a perspective view showing an outward appearance of the image input apparatus shown in FIG. 1; 
     FIG. 3 is a perspective view showing a state in which a camera head unit and a pan head unit of the image input apparatus shown in FIG. 1 are separate; 
     FIG. 4 is a perspective view showing a control terminal and an input/output terminal provided in the camera head unit of the image input apparatus shown in FIG. 1; 
     FIG. 5 is a perspective view showing a terminal and an input/output terminal of a pan head control switching mechanism provided in the pan head unit of the image input apparatus shown in FIG. 1; 
     FIG. 6 is a view showing a connecting state of operating portions of the control terminal of the camera head unit and the terminals of the pan head unit control switching mechanism; 
     FIG. 7 is a view showing a state before the operating portions of the control terminal of the camera head unit and the terminals of the pan head unit control switching mechanism are connected; 
     FIG. 8 is a perspective view showing the structure of a horizontal driver in the image input apparatus shown in FIG. 1; 
     FIG. 9 is a perspective view showing the structure of a vertical driver in the image input apparatus shown in FIG.  1 ; 
     FIG. 10 is a view showing patterns of pan head switching control modes in the image input apparatus shown in FIG. 1; 
     FIG. 11 is a graph showing the relation between the driving speed and the driving voltage of the pan head when the weight of a lens is used as a parameter; 
     FIG. 12 is a graph showing the relation between the pan head driving speed and the lens focal length when the focal length is used as a parameter; 
     FIG. 13 is a flowchart showing a pan head control switching operation in the image input apparatus shown in FIG. 1; 
     FIG. 14 is a flowchart showing an optical axis control operation in the image input apparatus shown in FIG. 1; and 
     FIG. 15 is a flowchart showing an initialization process of the optical axis control operation in the image input apparatus shown in FIG.  1 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A preferred embodiment of the present invention will now be described in conjunction with the accompanying drawings. 
     The image input apparatus shown in FIGS. 1 to  3  is composed of a camera head unit  21  and a pan head unit  22  which comprises an electric pan head for mounting the camera head unit  21  thereon. 
     As shown in FIG. 1, the camera head unit  21  comprises a zoom lens  1 , an iris  2 , an image pickup device  3 , a signal processing circuit  4 , a camera controller  5 , an iris driver  6 , a focus controller  7 , and a zoom controller  8 . The camera controller  5  is capable of mutual communication with the devices and the circuits within the camera head unit  21 . 
     The image pickup device  3  is, for example, a CCD (charge-coupled device) for converting an optical image obtained through the zoom lens  1  into electric signals. 
     The signal processing circuit  4  generates video signals by subjecting the electric signals from the image pickup device  3  to predetermined processing, and outputs the video signals to an external monitor (not shown) and a video recording/reproducing apparatus (also not shown) through a terminal Vout. Parameters related to the processing performed on the electric signals from the image pickup device  3  by the signal processing circuit  4  are controlled by the camera controller  5 . 
     The iris driver  6  drives the iris  2  so that the amount of light passing from the zoom lens  1  to the image pickup device  3  is a predetermined amount, that is, the electric signals from the image pickup device  3  are at a substantially constant level. The drive amount of the iris  2  is designated by the camera controller  5 . 
     The focus controller  7  drives some of the lenses constituting the zoom leans  1  so that the zoom lens  1  is focused on a predetermined subject. The drive amount is designated by the camera controller  5 . 
     The zoom controller  8  drives some of the lenses constituting the zoom lens  1  to obtain a predetermined focal length of the zoom lens  1 . The drive amount is designated by the camera controller  5 . 
     The camera controller  5  comprises a memory (not shown) and a CPU (also not shown). The CPU determines the drive amounts of the iris driver  6 , the focus controller  7 , and the zoom controller  8  based on information from an I/F controller  16 , which will be described later, and controls the processing operation of the signal processing circuit  4 . The memory stores data on the focal length and weight of the zoom lens  1  and the like. 
     The camera controller  5  is provided with an input/output terminal  10  for connecting the camera controller  5  to an external device (for example, a personal computer, a work station and a codec in a videoconference system) through the I/F controller  16  to allow communication therebetween. The control terminal  9  for connecting the camera controller  5  to a pan head control switching mechanism  11  of the pan head unit  22  which will be described later. The control terminal  9  is provided with three operating portions  9   a ,  9   b  and  9   c  for setting a pan head operation with respect to the camera head unit  21 . 
     The control terminal  9  and the input/output terminal  10  are, as shown in FIG. 4, formed in a support member  31  attached to the rear of a housing  21   a  of the camera head unit  21 . The operating portions  9   a ,  9   b  and  9   c  are spaced in parallel, and the shapes thereof are respectively determined in accordance with head operations set with respect to the camera head unit  21 . In this embodiment, the operating portion  9   a  is shaped like a projection, and the operating portions  9   b  and  9   c  are flat. The input/output terminal  10  is located adjacent to the operating portion  9   c.    
     The pan head unit  22  is, as shown in FIG. 3, provided with a pedestal  22   a  having a holding mechanism  42  for interchangeably holding the camera head unit  21 . The pedestal  22   a  is turned on the horizontal axis (in a pan direction) and on the vertical axis (in a tilt direction) by an optical axis controller  15 . This movement of the pedestal  22   a  changes the direction of the optical axis of the camera head unit  21 , that is, the image taking area. 
     The optical axis controller  15  comprises a horizontal driver  13  for driving the pedestal  22   a  in the pan direction, a horizontal position detector  13   a  for detecting the drive amount of the pedestal  22   a  in the pan direction, a vertical driver  14  for driving the pedestal  22   a  in the tilt direction, and a vertical position detector  14   a  for detecting the drive amount of the pedestal  22   a  in the tilt direction. The structures of the horizontal driver  13  and the vertical driver  14  will be described later. 
     The horizontal driver  13  and the vertical driver  14  are controlled by a pan head controller  12 , and the control amount is determined by using the driving voltage and the driving speed. The pan head controller  12  has a CPU (central processing unit; not shown) and a memory (also not shown). The CPU determines the aforesaid control amount for each of control modes previously stored in the memory. The control mode is selected based on a selection signal from a pan head control switching mechanism  11  as will be described later. In this embodiment, as shown in FIG. 10, eight control modes M 1 , . . . , M 8  are selectable with reference to the weight and the focal length of the lens  1  in the camera head unit  21 . 
     As the driving voltage in the control modes, one of three patterns set in accordance with the weight of the zoom lens  1  as shown in FIG. 11 is selected. The lens weight is divided into three regions, i.e., above 600 g, 600 g to 300 g and below 300 g, and the patterns of the driving voltage are set corresponding to the respective regions of the lens weight. Similarly, as the driving speed in the control modes, one of three patterns set in accordance with the focal length of the zoom lens  1  is selected as shown in FIG.  12 . The focal length of the zoom lens  1  is divided into three regions, a wide-angle lens focal length, a standard lens focal length, and a telephoto lens focal length, and the patterns of the driving speed are set corresponding to the respective regions. The driving speed is set such as to decrease as the focal length increases from the wide-angle lens to the telephoto lens. 
     The pan head control switching mechanism  11  provided on the holding mechanism of the pedestal  22   a  has three terminals  11   a ,  11   b  and  11   c  and an input/output terminal  17 . The terminal  11   a  is located to be opposed to the operating portion  9   a  of the control terminal  9  when the camera head unit  21  is attached to the pedestal  22   a . Similarly, the terminals  11   b , and  11   c  are positioned corresponding to the operating portions  9   b  and  9   c  of the control terminal  9 , respectively. The input/output terminal  17  is located to be opposed to the input/output terminal  10 . 
     The pan head control switching mechanism  11  also has a bracket  32  attached to the holding mechanism  42  of the pedestal  22   a  as shown in FIG.  5 . The bracket  32  comprises the terminals  11   a ,  11   b , and  11   c , the input/output terminal  17 , and a stopper  33  for positioning the support member  31  of the camera head unit  21 . The terminals  11   a ,  11   b  and  11   c  are spaced in parallel. 
     The terminals  11   a ,  11   b  and  11   c  are each, as shown in FIGS. 6 and 7, turnably supported at one end thereof by a shaft  25  attached to the bracket  32 , urged by a spring member  27  at the center thereof, and held in such a position that the other end thereof is in contact with a part of the bracket  32  against the spring force of the spring member  27  as shown in FIG.  7 . Actuating switches  26  are respectively opposed to the other ends of the terminals  11   a ,  11   b  and  11   c . When the terminal  11   a , lib or  11   c  is pressed by the corresponding operating portion  9   a ,  9   b  or  9   c  as shown in FIG. 6, the other end thereof presses the actuating switch  26 , thereby performing a turning-on operation. In other words, signals generated in response to the turning-on operations of the actuating switches  26  are given as selection signals to the pan head controller  12 , and the control mode is selected by the pan head controller  12  according to the combination of these selection signals. In short, selection signals for determining a proper control mode to the camera head unit  21  are generated by choosing respective shapes of the operating portions  9   a ,  9   b  and  9   c  such as to make the corresponding actuating switches  26  perform turning-on operations. In this embodiment, as mentioned above, eight control modes M 1 , . . . , M 8  are selectable with reference to the weight and focal length of the lens  1  in the camera head unit  1 . Since the operating portion  9   a  projects and the operating portions  9   b  and  9   c  are flat, the actuating switch  26  corresponding to the terminal  11   a  performs a turning-on operation and the actuating switches  26  corresponding to the other terminals  11   b  and  11   c  do not perform any turning-on operation, by which the control mode M 1  is selected. The control mode M 1  is set under the condition that the lens weight is less than 300 g and the focal length is standard. 
     When the bracket  32  is fitted on the support member  31  of the camera head unit  21 , the input/output terminal  17  is electrically connected to the input/output terminal  10 , by which the camera controller  5  and the I/F controller  16  are connected through the input/output terminals  10  and  17  so as to communicate with each other. 
     The I/F controller  16  receives an operation control signal from external equipment (such as a computer), and sends information about the camera head unit  21  and the pan head unit  22  to the external equipment. As is clear from the above description, the pan head controller  12  is capable of communication with other devices in the pan head unit  22 . 
     The structure of the horizontal driver  13  will be described in detail with reference to FIG.  8 . FIG. 8 is a perspective view showing the structure of the horizontal driver  13  in the image input apparatus shown in FIG.  1 . 
     The horizontal driver  13  has a stepper motor  51  supported by a support member (not shown), as shown in FIG. 8. A worm gear  52  is attached to an output shaft of the stepper motor  51  at one end, and rotatably supported by a base  61  at the other end thereof. A helical gear  53  mounted on a shaft  55  is meshed with the worm gear  52 . Both ends of the shaft  55  are rotatably supported by corresponding support plates  56 . 
     A worm gear  54  and a disk  57  with a plurality of slits  58  are fixed on the shaft  55 . A helical gear  62  mounted on a shaft  60  is meshed with the worm gear  54 . The shaft  60  is supported rotatably in the pan direction by the base  61 . 
     The helical gear  62  is provided with a pin (not shown) which projects toward the base  61  and actuates two microswitches  63  mounted on the base  61  in correlation to the rotation of the helical gear  62 . An initial position and an operation limit point (position) in the pan direction of the shaft  60  are sensed by actuating the microswitches  63  with the pin. 
     The disk  57  is located orthogonal to the optical path formed by a photointerrupter  59  to open and shut the optical path. The photointerrupter  59  detects a signal in response to the opening and closing of the optical path, and the detection signal is given to the horizontal position detector  13   a . The horizontal position detector  13   a  detects the rotation angle of the shaft  60  in the pan direction based on the detection signal from the photointerrupter  59 . 
     The structure of the vertical driver  14  will now be described in detail with reference to FIG.  9 . FIG. 9 is a perspective view showing the structure of the vertical driver  14  in the image input apparatus shown in FIG.  1 . 
     The vertical driver  14  is mounted on an operation table  71  attached to the shaft  60  of the horizontal driver  13  as shown in FIG. 9, and provided with a stepper motor  73 . 
     An output shaft of the stepper motor  73  is attached to a spur gear  74  which is meshed with a spur gear  75 . The spur gear  75  is integrally fixed to a worm gear  76 . Shaft portions  91  at both ends of the worm gear  76  are rotatably supported by bearings  77  attached to the operation table  71 , respectively. 
     The worm gear  76  is meshed with a helical gear  78  integrally fixed to a bevel gear  79 . The bevel gear  79  is meshed with a bevel gear  80  mounted on a shaft  83 . The shaft  83  is rotatably supported at the center thereof by a bearing  84  fixed on the operation table  71 . 
     Elliptic cams  88  are attached to both ends of the shaft  83 , and respectively fitted in cam grooves  90  formed on a camera head fixing plate  89 . The camera head fixing plate  89  is supported by the shaft portions  91  of the worm gear  76  so as to pivot on the shaft portions  91  in a tilt direction in correlation to the movement of the cams  88 . 
     The bevel gear  80  has a pin  81  which projects in parallel with the shaft  83  and actuates two microswitches  82  and  92  in correlation to the rotation of the bevel gear  80 . The microswitches  82  and  92  are mounted on the operation table  71 . An initial position and an operation limit point (position) in the tilt direction of the camera head fixing plate  89  are sensed by actuating the microswitches  82  and  92  with the pin  81 . 
     A disk  85  with a plurality of slits  86  is fixed on the shaft  83 . 
     The disk  85  is located orthogonal to the optical path formed by a photointerrupter  87  to open and shut the optical path. The photointerrupter  87  detects a signal in response to the open and shut of the optical path, and the detection signal is given to the vertical position detector  14   a . The vertical position detector  14   a  detects the rotation angle of the camera head fixing plate  89  in the tilt direction based on the detection signal from the photointerrupter  87 . 
     A pan head control switching operation in the image input apparatus will now be described with reference to FIG.  13 . FIG. 13 is a flowchart showing the pan head control switching operation in the image input apparatus shown in FIG.  1 . 
     When the camera head unit  21  is mounted on the pan head unit  22 , as shown in FIG. 13, the support member  31  of the camera head unit  21  (shown in FIG. 4) is fitted in the bracket  32  of the pan head unit  22  (shown in FIG. 5) (Step S 101 ). 
     The terminals  11   a ,  11   b  and  11   c  are pressed by the corresponding operating portions  9   a ,  9   b  and  9   c  in correlation to the fitting of the support member  31  and the bracket  32 . Then, the actuating switches  26  are pressed by the other ends of the terminals  11   a ,  11   b  and  11   c , thereby performing turning-on operations. In other words, signals generated by the turning-on operations of the actuating switches  26  are given as selection signals to the pan head controller  12 , and one of the control modes M 1 , . . . , M 8  is selected by the pan head controller  12  according to the combination of these selection signals (step S 102 ). In this embodiment, the terminal  11   a  is pressed by the operating portion  9   a , the actuating switch  26  corresponding to the terminal  11   a  performs a turning-on operation, and other actuating switches  26  do not perform any turning-on operations, by which the control mode M 1  is selected. 
     Next, it is judged whether or not the selected control mode is Mode M 8  (Step S 103 ). If the selected control mode is M 8 , that is, if the camera head unit  21  is not mounted on the pan head unit  22 , the process ends. 
     If the selected control mode is a mode other than M 8 , data corresponding to the selected control mode is read from the memory (Step S 104 ), and the driving voltage in accordance with the lens weight is set (Step S 105 ). After setting the driving voltage, the driving speed in accordance with the lens focal length is set (Step S 106 ). 
     Accordingly, when the camera head unit  21  is mounted on the pan head unit  22 , the driving voltage and driving speed best-suited to the weight and focal length of the zoom lens  1  in the camera head unit  1  are automatically selected. Specifically, when a light lens is mounted, that is, when the camera head unit  21  is light, the driving voltage is set at a low value, which achieves small power consumption and reduced noise. When a wide-angle lens is used, since the driving speed of the pan head unit  22  is set high, an arbitrary subject can be captured instantaneously. When a telephoto lens is used, a subject can be captured accurately by driving the pan head unit  22  at low speed. As mentioned above, when the camera head unit  21  is mounted on the pan head unit  22 , the optimum pan head operation with reference to the weight and focal length of the zoom lens  1  in the camera head unit  21  can be selected automatically, and the selection of the pan head operation best-suited to the camera head unit  22  can be simplified. 
     Since the size of the camera head unit  21  capable of being mounted on the pan head unit  22  is predetermined, there is no need to excessively increase the driving force of the pan head unit  22  and the rise in cost of the pan head unit  22  can be restricted. 
     Furthermore, since the pan head unit  22  interchangeably mounts the camera head unit  21  thereon, it is possible to select the camera head unit  21  having a lens suited to the intended use and to obtain high general versatility. 
     An optical axis control operation will now be described with reference to FIG.  14 . FIG. 14 is a flowchart showing an optical axis control operation of the image input apparatus shown in FIG.  1 . 
     After the camera head unit  21  is mounted on the pan head unit  22 , an external device for giving operation guidance to the camera head unit  21  and the pan head unit  22  is connected to a terminal I/F of the pan head unit  22  through a cable. After the completion of the connection, the camera head unit  21  and the pan head unit  22  are capable of operation. 
     Referring to FIG. 14, first, a command from the external device is waited for (Step S 202 ). When a command is input from the external device, it is judged by the I/F controller  16  whether or not the input command is a command relating to the pan head unit  22  (Step S 203 ). If the input command is not a command relating to the pan head unit  22 , that is, if the input command is a command relating to the camera head unit  21 , the command is sent from the I/F controller  16  to the camera controller  5  through the input/output terminals  17  and  10 . Based on the command, the zoom operation of the zoom lens  1 , the operation of the iris  2  and the like are controlled (Step S 214 ). 
     When the input command relates to the pan head unit  22 , it is judged whether or not the command is an initialization command (Step S 204 ). If the command is an initialization command, it is sent to the pan head controller  22 , which executes an initialization process for setting the optical axis of the zoom lens  1  in an initial position (Step S 215 ). The initialization process will be described in detail later. 
     If the input command is not an initialization command, that is, if the input command is information for designating the angle of the optical axis in the pan direction or the tilt direction, the angle designated by the command is converted into positional information (Step S 205 ), and the positional information is stored as a designated position in the memory (Step S 206 ). 
     Subsequently, it is judged whether or not the current position of the optical axis agrees with a designated position (Step S 207 ). If the optical axis is currently in the designated position, the process from Step S 201  on is executed again. 
     If the current position of the optical axis does not agree with the designated position, the stepper motor  51  of the horizontal driver  13  or the stepper motor  73  of the vertical driver  14  is driven to start the angle adjustment in the pan direction or the tilt direction so that the optical axis reaches from the current position to the designated position (Step S 208 ). 
     After the angle adjustment in the pan direction or the tilt direction is started, it is judged whether or not the horizontal driver  13  or the vertical driver  14  reaches an operation limit point before the optical axis reaches from the current position to the designated position (Step S 209 ). If it is judged that the horizontal driver  13  or the vertical driver  14  reaches the operation limit point before the optical axis reaches from the current position to the designated position, a positional information correction process is carried out to reset the designated position stored in the memory (Step S 210 ), and the stepper motor  51  of the horizontal driver  13  or the stepper motor  73  of the vertical driver  14  is stopped (Step S 212 ). After the stepper motor  51  or  73  is stopped, the process from Step S 201  on is executed again. 
     If it is judged that the horizontal driver  13  or the vertical driver  14  does not reach the operation limit point before the optical axis reaches from the current position to the designated position, the position of the optical axis is sequentially updated by a computation such as addition or substraction, and the stepper motor  51  of the horizontal driver  13  or the stepper motor  73  of the vertical driver  14  is driven until the optical axis reaches from the current position to the designated position (Step S 211 ). When the optical axis reaches the designated position, the current position stored in the memory is updated (Step S 213 ). After updating the current position, the process from Step S 201  on is executed again. 
     When the command input from the external device is a command for the camera head unit  21 , it is sent from the I/F controller  16  to the camera controller  5  through the input/output terminals  17  and  10 . When the input command is a command for the pan head unit  22 , it is sent from the I/F controller  16  to the pan head controller  12 . Accordingly, it is possible to combine a control line for the camera head unit  21  and a control line for the pan head unit  22  into one line, and thereby, to eliminate excess trouble of separately laying the control lines for the camera head unit  21  and the pan head unit  22  as in the conventional apparatus in which a camera can be mounted on a pan head. Furthermore, since the I/F controller  16  is set to communicate with the external device, there is no need to add a special connecting device which allows communication between the I/F controller  16  and the external device. 
     Next, the initialization process for the pan head unit  22  will be described with reference to FIG.  15 . FIG. 15 is a flowchart showing an initialization process in the optical axis control operation of the image input apparatus shown in FIG.  1 . 
     In the initialization process, initialization in the horizontal direction is first performed. When the initialization in the horizontal direction is started, as shown in FIG. 15, directions are given to make a turn in an A direction (for example, a horizontal and clockwise direction), and the stepper motor  51  of the horizontal driver  13  is driven (Step S 301 ). The drive of the stepper motor  51  in the horizontal driver  13  is continued until an operation limit point of the shaft  60  is detected in response to the actuation of the microswitch  63 . When the operation limit point is detected, the stepper motor  51  is stopped (Steps S 302  and S 303 ). 
     When the stepper motor  51  is stopped, positional information corresponding to the operation limit point is stored in the memory (Step S 304 ). 
     Next, directions are given to make a turn opposite to the A direction (in a horizontal and counterclockwise direction), the stepper motor  51  of the horizontal driver  13  is driven (Step S 305 ), and the current positional information is calculated by subtracting positional information corresponding to the drive amount of the stepper motor  51  from the positional information stored in the memory (Step S 306 ). The positional information corresponding to the drive amount of the stepper motor  51  is found from the rotation angle of the shaft  60  in the pan direction obtained based on the above-mentioned detection signal of the photointerrupter  59 . 
     The stepper motor  51  is driven until the calculated current positional information agrees with predetermined information designated and stored in the memory. When the current positional information agrees with the designated information stored in the memory, the stepper motor  51  is stopped (Steps S 307 , S 308 ). After the stop of the stepper motor  51 , the initialization process in the horizontal direction ends. 
     Subsequently, initialization in the vertical direction is performed by using a similar procedure to the initialization in the horizontal direction. The description of the initialization in the vertical direction is omitted in this embodiment. 
     Thus, an absolute value of the optical axis of the zoom lens  1  can be detected and the direction of the optical axis can be set arbitrarily by executing the initialization process. 
     Although the camera head unit  21  is moved by the operation of the optical axis controller  15  in this embodiment, the camera head unit  21  and the signal processing circuit  4  may be separated from each other, a package for housing the zoom lens  1 , the image pickup device  3  and the like together may be driven by the optical axis controller  15 . 
     If there is no need to greatly change the image taking area (position), a driving method for changing the relative position between the zoom lens  1  and the image pickup device  3 , a method of changing the optical axis of incident light by placing a variable vertical angle prism in front of the zoom lens  1 , or a method of changing the angle relative to the optical axis by placing a plate glass member (whose opposite surfaces are parallel) in the optical path may be adopted. Furthermore, mode information stored in the memory may be read into the pan head unit when the camera head unit is mounted on the pan head unit. Still further, more accurate motion control can be exerted by storing information about the lens weight, focal length and the like in the memory, not as mode information, but as concrete numeric values. 
     The pan head in the above-mentioned embodiment is equipped with a holding mechanism attached to a pedestal to interchangeably hold an image pickup device, and a pan head control switching mechanism for performing switching so as to select and control a pan head operation suited to the image pickup device when the image pickup device is mounted on the holding mechanism. The pan head operation corresponding to the image pickup device is selected and carried out by a drive means based on the switching operation of the pan head control switching mechanism. Therefore, it is possible to achieve an image input apparatus which is excellent in general versatility and low in cost and is capable of changing pan head control with no trouble. 
     In addition, since the pan head has an input/output terminal to be connected to an input/output terminal of the image pickup device for signals relating to control when the image pickup device is mounted on the holding mechanism, the trouble of laying another control line separate from a control line for the image pickup device can be eliminated. 
     The individual components shown in outline or designated by blocks in the Drawings are all well-known in the image recording arts, and their specific construction and operation are not critical to the operation or best mode for carrying out the invention. 
     While the present invention has been described with respect to what is presently considered to be the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.