Abstract:
A camera has a lens portion and an imaging portion arranged on a rotating stand of a pan/tilt apparatus. The pan/tit apparatus includes a device frame; a rotating stand; a regulating device for defining two end positions of an operational range of the rotating stand, and a drive device for driving the rotating stand. The drive device has a rotor and a stator. The rotor has a permanent magnet and an output shaft for engaging an arm portion of the rotating stand. The stator includes an excitation coil for applying a rotational force to the permanent magnet when an electrical current flows in the excitation coil. An electric control device controls the electrical current.

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT 
   This invention relates to an electronic pan and tilt apparatus that can change a direction of an electronic still or video camera, and also relates to a camera that employs the same. 
   Conventionally, in a camera with remote operation capability such as a video camera operated by remote control, a motor drives the camera through a gear mechanism to change a direction thereof by moving a camera unit up and down or left and right. 
   Many of such cameras are equipped with a zoom function from 8 to 20 magnifications. It is also common to pan and tilt the camera in multiple directions within an operating range of the camera. In setting a shooting direction, a direction toward a subject and a zoom magnification are determined while viewing an image on a monitor. Alternatively, a predetermined direction and a zoom magnification are stored in a memory for automatic adjustment of the camera. 
   Such a pan/tilt camera is suitable for shooting a subject at a far and wide area to display a large figure on a monitor. However, as a door camera to just swing vertically to see a person according to a height, or as a camera for shooting inside a house, it is insufficient to recognize the subject if a camera has a short focal point and a lens view angle of approximately 50° directed in only two or three directions. 
   In recent years, such a single focus lens cameras has become smaller, and the whole system including a lens, an imaging unit and a processing unit can fit into even a two square centimeter area. However, when such a camera is driven by a motor with gears to tilt like the conventional device, a size of the combined device increases due to the tilt apparatus, making it difficult to take advantage of the small camera size. 
   Even in the case that only two or three shooting directions are necessary, the conventional control method needs to detect the shooting directions and store the direction information in a memory. Thus, it is difficult to reduce a cost and a size of the device and to simplify the control mechanism. 
   Also, when shooting a far and wide area, a subject is mostly in a horizontal position. For example, only a limited vertical shooting range is necessary for an outdoor monitoring camera, as there is no need to shoot a sky or a ground. It is sufficient to move a camera slightly up and down to cover a difference in heights among persons when shooting a participant in a group during a TV conference. For such a use, the conventional camera, which has the same range in both vertical and horizontal directions, has more than enough pan/tilt capability, resulting in an unnecessary high price. 
   In view of resolving the problems, an object of the present invention is to provide a camera with a simple and low cost pan/tilt apparatus. 
   Further objects and advantages of the invention will be apparent form the following description of the invention. 
   SUMMARY OF THE INVENTION 
   According to the present invention, a pan camera is equipped with a permanent magnetic rotor that has two magnetic poles and moves reciprocally by a predetermined rotation angle within 180°; a fixed excitation coil; an output shaft fixed to the rotor; and at least a lens and an imaging unit that engages the output shaft to move. The rotor rotates in left and right directions by a magnetic effect on the rotor according to a current direction flowing through the excitation coil, and stops at either of two end positions of an operational range. The imaging unit faces one of two shooting directions at either of the two end positions, and maintains the shooting direction while an electrical current flows in the excitation coil. 
   Also, according to the present invention, a pan camera is equipped with a permanent magnetic rotor that has two magnetic poles and moves reciprocally by a predetermined rotation angle within 180°; a fixed excitation coil; an output shaft fixed to the rotor; and at least a lens and an imaging unit that engages the output shaft to move. The rotor is held at central and both end positions of rotation by an urging force and a magnetic effect on the rotor according to an electrical current flowing through the excitation coil. The imaging unit faces three shooting directions at the center and both end positions, and maintains one of the three shooting directions according to a current direction or no current. 
   According to the present invention, the camera capable of panning and tilting in two or three directions can be made small, inexpensive and easy for remote control. Furthermore, the control device has a simple structure because the control operation involves only the current direction in the excitation coil and the switching of the power. 
   Also, this tilting mechanism may be employed only for up and down directions, and a conventional mechanism may be employed for left and right directions to reduce a cost by removing unnecessary functions. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of an overall structure of the invention; 
       FIG. 2  is an explanatory view showing a shooting direction of a two-direction pan camera; 
       FIG. 3  is an exploded perspective view showing a rotor portion of the two-direction pan camera; 
       FIG. 4  is an exploded perspective view showing a solenoid actuator of the two-direction pan camera; 
       FIG. 5  is an explanatory view showing an operation of the two-direction pan camera; 
       FIG. 6  shows a holding device of the two-direction pan camera; 
       FIG. 7  is an explanatory view showing an operation of the two-direction pan camera; 
       FIG. 8  is an explanatory view showing an operation of the two-direction pan camera; 
       FIG. 9  is an explanatory perspective view showing a shooting direction of a three-direction pan camera; 
       FIG. 10  is an exploded perspective view showing a rotor portion of the three-direction pan camera; 
       FIG. 11  is an exploded perspective view showing a solenoid actuator of the three-direction pan camera; 
       FIG. 12  is an explanatory view showing an operation of the three-direction pan camera; and 
       FIG. 13  shows a holding device of the three-direction pan camera. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Hereunder, embodiments of the invention will be explained with reference to the accompanied drawings. The embodiments relate to a pan/tilt camera that uses an electrically powered panning device according to the present invention. The pan/tilt camera changes a shooting direction by panning to up, down, left and right directions. 
     FIG. 1  shows a general configuration of an entire apparatus. A camera unit  3  is equipped with a lens unit  1  and an imaging unit  2 , and is supported on a rotating frame  5  by rotating axes  3 A and  3 B formed on a vertical axis Y so that the camera unit can rotate. A lens axis Z is a shooting direction and is movable in a direction L. An output shaft  7  of a solenoid actuator  6  screwed to the rotating frame  5  engages a slit  3 C formed on the camera unit  3 . The solenoid actuator  6  drives the camera. 
   Distal ends of adjustment screws  8  and  9  (distal end of the adjustment screw  8  is  8 A) mounted to the rotating frame  5  abut against an arm portion  3 D formed on the camera unit  3 A to regulate a rotational range of the camera unit  3 . An amount of protruding portions of the adjustment screws  8  and  9  can be adjusted by rotating the screws. As shown in  FIG. 2 , the shooting direction in the direction or range L for the lens axis Z can be adjusted to stop at the both end positions. 
   Other than the configuration shown above, it is perfectly acceptable to establish adjustable means on other moving parts for regulating the shooting direction in the direction L for the lens axis Z at both end positions. 
   In the above structure, the camera can pan left and right in the direction or range L. The following will describe an operation related to a vertical movement of the camera in a direction H. 
   The rotating frame  5 , which supports the camera unit  3  and the solenoid actuator  6 , is supported on a support body  10  by rotating shafts  5 A and  5 B formed on a horizontal axis X of the rotating frame  5 , so that the lens axis Z of the shooting direction is movable along the direction or range H. An output shaft  12  of a solenoid actuator  11  screwed to the support body  10  engages a slit  5 C formed on the rotating frame  5 . The solenoid actuator  11  drives the rotating frame. 
   Protruding portions  11 A and  11 B formed on the solenoid actuator  11  abut against an arm portion  5 D formed on the rotating frame  5  to limit a rotational range of the rotating frame  5 , so that both end positions of the shooting direction of the lens axis Z in the direction H are defined. Although the above example is provided for the present embodiment, it is perfectly acceptable to establish adjustable means on other moving parts for regulating the shooting direction in the H direction for the lens axis Z at both end positions. 
   According to the present invention, the same panning mechanism is provided for both the vertical and horizontal directions. However, it is perfectly acceptable to combine the conventional panning mechanism with the panning mechanism according to the present invention depending on a shooting range and a position of a shooting target. 
   The following describes an internal configuration of the solenoid actuator. As clearly shown in  FIG. 3 , an output shaft  7  is inserted at the center of a magnetic rotor  20  having a cylindrically shape and two magnetic poles, so that the output shaft  7  is supported and rotates inside of bobbins  22  and  23 . 
   Further, an excitation coil  24  is arranged to surround the rotor  20  inside the joined bobbins  22  and  23  as shown in  FIG. 4 . Terminal pins  26  and  27  are fastened to the bobbin  22  to wind wire ends of the excitation coil  24 . Also, strong magnetic bodies  28  and  29  are disposed in holes established on the bobbin  22 . 
   A drive unit  30  configured above is surrounded by a hollow, cylindrically shaped magnetic circuit member (yoke)  31 , a conductive wire print board  32  connected to the excitation coil  24  and a cover  33 , and retained therein. 
   Operations of the camera unit and the solenoid actuator will be explained below.  FIG. 5  shows relationships of the operations. In the rotor with the two magnetic poles, the N pole is magnetically attracted to the strong magnetic body  29 . The arm portion  3 D formed on the camera unit  3  abuts against the adjustment screw  8  to stop at the first stopping position, and the shooting direction of the camera unit  3  faces a direction A. The second stopping position of the rotor  20  is a position where the S pole is magnetically attracted to the strong magnetic body  28  and the arm portion  3 D abuts against the adjustment screw  9 , where the shooting direction of the camera unit  3  faces a direction B. 
   The rotor  20  rotates in either a clockwise or a counterclockwise direction according to a current flow direction in the excitation coil  24  through the magnetic effect of the rotor  20 . An electrical pulse current flows in the excitation coil for a period of time need just enough to rotate, and the magnetic attraction between the pole on the rotor and the strong magnetic body is enough to hold the camera unit at the stopping position thereby conserving electrical power. Also, as the way other than that described above for holding the camera unit at the stopping position, as shown in  FIG. 6 , a tension spring  34  stretched between the rotating frame  5  and the output shaft  7  may be employed as a way for holding the camera unit at the stopping position. 
   The shooting directions A and B for the camera unit shown in  FIG. 5  are determined by adjusting either of the screw  8 , or  9 , which abuts against the arm portion  3 D formed on the camera unit  3 . As shown in  FIG. 1 , the screw  8  or  9  can rotate to adjust the amount of protrusion of distal ends to change the shooting directions A and B. Shooting ranges of A 1  and B 1  in the shooting directions A and B may be overlapped to eliminate a dead angle in the panning range of the camera unit. 
   As shown in  FIG. 7 , the strong magnetic body  29  may be arranged only on the N pole side of the rotor  20 . The N pole of the rotor  20  is magnetically attracted to the strong magnet  29  within the rotational range. When a current flows in the excitation coil  24  to rotate the rotor  20  in a direction opposite to the attracted direction, the rotor  20  rotates and the shooting direction faces the direction B. The arm portion  3 D formed on the camera unit  3  abuts against the adjustment screw  9  to stop and is held there. Also, by turning OFF the current flow in the excitation coil  24 , the rotor  20  rotates and the arm portion  3 D abuts against the adjustment screw  8  and is held there. Thus, the shooting direction faces the direction A. The strong magnetic body may be on the S pole side, and the attractive force may also be supplied by a spring or other elastic member. 
   As shown in  FIG. 8 , the strong magnetic body may be omitted. The rotor  20  rotates to the left or right directions depending on the current direction flowing in the excitation coil  24 . The arm portion  3 D formed on the camera unit  3  abuts against either of the adjustment screws  8  or  9  to stop, and the camera unit  3  is hold at that position, so that the shooting direction faces the direction A or B. 
   Next, a three-direction pan camera will be explained as shown in the  FIG. 9 . An overall configuration of the camera unit is the same as that shown  FIG. 1 , so the explanation has been omitted. 
   In a solenoid actuator, as shown in  FIG. 10 , the output shaft  7  is inserted and fixed in the center of the magnetic rotor  20  having a cylindrical shape and two magnetic poles therein, and is supported to rotate in the bobbins  22  and  23 . 
   Further, the excitation coil  24  is arranged to cover the rotor  20  inside the bobbins  22  and  23  as shown in  FIG. 11 . The terminal pins  26  and  27  are fixed on the bobbin  22  to wind the wire ends of the excitation coil  24 . The drive unit  30  of the configuration described above is enclosed and fits inside the hollow, cylindrically shaped magnetic circuit member (yoke)  31 , the conductive wire print board  32  connected to the excitation coil  24  and the cover. Furthermore, the yoke  31  is provided with protruding portions  31 A and  31 B protruding toward inside thereof at two locations on a circumference of the yoke. 
   Operations of the camera unit and the solenoid actuator will be explained below.  FIG. 12  shows a relationship of the operations. When there is no current flowing in the excitation coil  24 , the rotor  20  with the two magnetic poles is held with the N pole and the S pole being attracted to each of the protruding portions  31 A and  31 B on the yoke  31 , thereby the camera unit  3  being directed to the direction A. 
   Another holding means for the shooting direction of the camera unit  3  to face the direction A may also be achieved through the tension spring  34 , as shown in  FIG. 13 , stretched between the rotating frame  5  and the arm portion  3 D on the camera unit  3 . Either of the holding methods is acceptable. 
   Also, when an electrical current flows in the excitation coil  24 , the rotor  20  rotates in either the clockwise or the counterclockwise direction depending on the current flow direction in the excitation coil  24  and the magnetic effect on the rotor  20 . When the electrical current continues to flow, the arm portion  3 D formed on the camera unit  3  abuts against the adjustment screws  8  or  9  and stays at the position, thus the shooting direction of the camera faces the direction B or C. 
   The shooting direction A shown in  FIG. 12  is determined by the positions of the protruding portions  31 A and  31 B established on the yoke  31 , so it is possible to change the shooting direction by rotating the yoke  31  to change the positions of the protruding portions  31 A and  31 B. 
   Also, the shooting directions B and C are determined by the adjustment screws  8  and  9  that abut against the arm portion  3 D formed on the camera unit  3 . As shown in  FIG. 1 , it is possible to adjust the amount of protrusion of the distal ends of the adjustment screws  8  or  9  by rotating them thereby changing the shooting directions A and B. In such a case, the shooting ranges of A 1 , B 1  and C 1  may overlap with each other to eliminate the dead angle in the panning range of the camera unit. 
   The pan/tilt camera configuration according to an embodiment of the present invention has been explained, but the camera unit  3  in  FIG. 1  may be applied to a removable pan/tilt apparatus. 
   While the invention has been explained with reference to the specific embodiments of the invention, the explanation is illustrative and the invention is limited only to the appended claims.