Apparatus for turning monitoring camera

There is disclosed a monitoring camera turning apparatus. An angle sensor continuously detects the turning angle of a turning shaft for turning a monitoring camera. Two detected angles are recorded as boundary limit angles in a recorder at the moment of generation of trigger signals. In a comparator, the recorded boundary limit angles are compared with the turning angle detected by the angle sensor at a moment. In accordance with results of this comparison, a switch device changes a direction of rotation of the turning shaft, thereby turning the monitoring camera in a monitoring range.

FILED OF THE INVENTION AND RELATED ART STATEMENT 
This invention relates to an apparatus for turning or angularly moving a 
monitoring camera which installed indoors or outdoors for monitoring 
purposes. 
In a conventional turning apparatus, a monitoring camera is mounted on a 
turning shaft, and an arm extends radially outwards from the turning 
shaft. A pair of limit switches are mounted on a distal end of the arm. 
Two stopper members are disposed at angularly or circumferentially-spaced 
positions in an arc path along which the distal end of the arm moves. The 
turning shaft is rotated by a motor to turn or rotate (angularly move) the 
monitoring camera. When one limit switch is brought into contact with one 
stopper member, the direction of rotation of the motor is reversed, so 
that the turning shaft is rotated in a reverse direction. When the other 
limit switch is brought into contact with the other stop member, the 
direction of rotation of the motor is reversed again, so that the turning 
shaft is rotated in the former direction. In this manner, the monitoring 
camera is repeatedly changed in the turning direction and angularly 
reciprocated within a predetermined monitoring angular area. However, in 
the above conventional turning apparatus, in order to vary the monitoring 
range, it is necessary to change the positions of the stopper members, and 
this is rather cumbersome. Further, it is impossible for the conventional 
turning apparatus to arbitrarily select one from two or more different 
monitoring ranges preset. Further, unless the monitoring camera is turned 
after the installation, it is not possible to exactly know the range of 
coverage by the monitoring camera. Therefore, there has been encountered a 
problem that the range of coverage by the monitoring camera differs from a 
desired one. 
OBJECT AND SUMMARY OF THE INVENTION 
It is an object of this invention to provide a monitoring camera turning 
apparatus in which the monitoring range can be easily changed, and a 
desirable monitoring range can be arbitrarily selected from two or more 
monitoring ranges preset, and the range of coverage by the monitoring 
camera exactly corresponds to a desired monitoring range. 
To this end, according to the present invention, there is provided an 
apparatus for turning a monitoring camera comprising means for mounting 
the monitoring camera, means for detecting a turning angle of the mounting 
means, means for recording therein a pair of turning angles detected by 
the detecting means as monitoring boundary limit angles, means for 
comparing the recorded monitoring boundary limit angles with a turning 
angle detected by the detecting means at a moment, and means for changing 
a direction of turning of the mounting means in accordance with results of 
comparison by the comparing means.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1, a turning shaft 1 extends through a stationary disk 2. 
The shaft 1 is rotatably borne by a ball bearing 3 fixed on the disk 2. A 
holder 4 for monitoring camera 5 is provided on a one end of the turning 
shaft 1. A motor 6 is so disposed on the disk 2 that an output shaft 61 
thereof extends in parallel to the turning shaft 1. A driving gear 7 is 
mounted on an end of the output shaft 61 of the motor 6. A driven gear 8 
is so fixed to the turning shaft 1 that the driving gear 7 engages with 
the driven gear 8 to turn the turning shaft 1. 
An angular sensor 9 is mounted on the other end of the turning shaft 1. The 
sensor 9 may include a potentiometer in which an angular displacement is 
converted into a change of electric resistance, synchro angular 
displacement sensing device utilizing electromagnetic induction, or a 
resolver angular displacement sensing device. Further, an encoder can be 
used as the angular sensor 9. The angular sensor 9 comprises a movable 
portion for turning or angular movement with the turning shaft 1, and a 
stationary portion. The stationary portion is secured to the stationary 
disk 2 through a bracket 10. The data representing turning angles of the 
shaft 1 detected by the angular sensor 9 are fed to a recorder 11 and a 
comparator 12. The comparator 12 is connected to a switching device 14. 
The switch device 14, in accordance with the comparison result in the 
comparator 12, changes the direction of rotation of the motor 6. 
The operation of the turning apparatus of the first embodiment will now be 
described hereinafter. When the motor 6 is operated to turn or angular 
move the turning shaft 1 through the drive gear 7 and the driven gear 8, 
the angular sensor 9 continuously detects the turning angle of the shaft 
1, and feeds it to the recorder 11 and the comparator 12. An operator 16 
watches a picture in a monitor television 17 picked up by the video camera 
5 and then sets the monitoring range of the video camera 5. More 
specifically, when the video camera 5 is turned and then it reaches each 
boundary of desired monitoring range, a trigger signal 13 is fed to the 
recorder 11 by the operator 16 through a control device 15. When the 
recorder 11 receives the trigger signal 13, it records the detected 
turning angle at the moment as a boundary limit angle. In this manner, two 
detected turning angles are recorded in the recorder 11 to determine or 
set the monitoring angular range. 
Thereafter, when the turning shaft 1 is turned, the turning angle thereof 
continuously detected by the angular sensor 9 is fed to the comparator 12 
in which the detected angle is compared with the boundary limit angles 
recorded in the recorder 11. When the detected angle coincides with one of 
the recorded boundary limit angles, the comparator 12 outputs a command 
signal to the switch device 14 so as to change over or reverse the 
direction of rotation of the motor 6. Then, the turning shaft 1, or the 
video camera 5 turns in a reverse direction. When the detected angle 
coincides with other recorded boundary limit angle, the comparator 12 
outputs a command signal again to switch device 14 so as to reverse the 
direction of rotation of the motor 6 again. In this manner, the turning 
shaft 1 and the video camera 5 are repeatedly changed in the turning 
direction and angularly reciprocated between the recorded boundary limit 
angular positions. 
In the first embodiment, the monitoring range between the boundary limit 
angular positions can be arbitrarily set by recording the boundary limit 
angles detected by the angular sensor 9 in the recorder 11 in advance. The 
setting can be conducted without mechanical process. Therefore, it is 
possible not only to set or change the monitoring range, but also to set 
two or more monitoring ranges. Further, since the setting can be carried 
out while watching a picture picked up by the video camera (monitoring 
camera), a desired monitoring range exactly coincides with the actual 
monitoring range. 
On the other hand, in a conventional monitoring camera turning apparatus 
shown in FIG. 7, a turning shaft 101 extends through a stationary disk 
102. The shaft 101 is rotatably borne by a ball bearing 103 fixed on the 
disk 102. A holder 104 for monitoring camera 105 is provided on a one end 
of the turning shaft 101. A motor 106 is so disposed on the disk 102 that 
an output shaft 161 thereof extends in parallel to the turning shaft 101. 
A driving gear 107 is mounted on an end of the output shaft 161 of the 
motor 106. A driven gear 108 is so fixed to the turning shaft 101 that the 
driving gear 107 engages with the driven gear 108 to turn the turning 
shaft 101. 
An arm 201 extends radial outwards from the turning shaft 101, and two 
limit switches 202 are attached to opposite sides of a distal end of the 
arm 201. A ring shaped flange 121 is formed on the periphery of the disk 
102. Two metal members 122 are so disposed at two positions of the flange 
121 angularly spaced from each other that the limit switches 202 abut 
these metal members 122. The metal member 122 is attached to the flange 
121 by means of a screw 123. The limit switches 202 are electrically 
connected to the motor 106 through a switch device 114. Each time the 
limit switch 202 abuts on the metal member 122, the switch device 114 
alternates the direction of rotation of the motor 106. 
Therefore, in the conventional apparatus, in order to change the monitoring 
range, it is necessary to loosen the screws 123 by the screw driver 124 so 
as to relocate the metal members 122 and to tighten the screws 123 again. 
This is cumbersome. 
To the contrary, according to the present invention, it is possible to 
avoid these troubles. 
In an embodiment according to the present invention shown in FIG. 2, an 
angular sensor 9 comprises a pulse encoder 91 and a pulse counter 92. With 
this arrangement, the absolute value of the angular position of the 
turning shaft 1 can be detected. 
When the turning shaft 1 is turned, pulses are fed from the pulse encoder 
91 to the pulse counter 92 in which the number of pulses received are 
counted. The absolute value of the angular position of the turning shaft 
is detected by the number of the pulses thus counted. 
With this construction, similar effects as described in connection with the 
first embodiment can be achieved. 
In an embodiment shown in FIG. 3, the recorder 11 comprises a first 
recording portion 111, a second recording portion 112 and a third 
recording portion 113. The another elements corresponding to those shown 
in FIG. 1 are referenced by the same numerals, and the description of the 
operations thereof is omitted. The first recording portion 111 can record 
not less than three angles (A1, A2, A3, A.sub.i, . . . An) from the 
angular sensor 9. The second recording portion 112 records two angles 
(A.sub.k, A.sub.1) selected from the angles (A1, A2, A3, A.sub.i, . . . 
An) recorded in the first recording portion 111 as a combination (B.sub.j) 
of boundary limit angles. The second recording portion 112 can record not 
less than two combinations (B1, B2, Bj, . . . Bm). The third recording 
portion 113 records one pair of combinations (Bp, Bq) selected from the 
combination group (B1, B2, Bj, . . . Bm) recorded in the second recording 
portion 112. These recording operations are effected by the control device 
15. More specifically, the operator 16 operates the control device 15 so 
as to output a trigger signal 151 to the first recording portion 111, 
which makes the first recording portion 111 record a turning angle 
(A.sub.i) of the turning shaft 1 detected by the angular sensor 9 at the 
moment. The operator 16 operates the control device 15 to make the second 
recording portion 112 select two angles (A.sub.k, A.sub.1) as a 
combination (B.)3 of boundary limit angles, which represent a monitoring 
range of the monitoring camera 5 and record two or more such combinations 
(B1, B2, B.sub.j, . . . Bm) . The operator 16 further operates the control 
device 15 to make the third recorder select one pair of combinations 
(B.sub.p, B.sub.q) selected from the combination group (B1, B2, B.sub.j, . 
. . Bm) and record such pair. The timing of these operations of the 
control device 1 can be carried out by the operator 16 with monitoring a 
monitor television 17 connected through a coaxial cable 18 to the 
monitoring camera 11. 
According to the third embodiment, a plurality of different turning range 
combinations, for example, B1 and B2 (FIG. 4), can be beforehand set, and 
a desired one can be selected according to the requirement. For example, 
in case that the selection is effected with using a timer, one monitoring 
range (B1) is employed for a certain time zone, and another monitoring 
range (B2) is employed for another time zone, instead of (B1). Thus, the 
monitoring range can be automatically changed in accordance with the time 
zone. 
Of course, selected monitoring ranges may be partially overlapped with each 
other or apart from each other. 
Although the monitoring camera is turned in a single plane in the above 
three embodiments, the monitoring camera can be turned in a combination of 
two planes. Namely, a three-dimensional movement of the monitoring camera 
can be obtained. A fourth embodiment is a device for permitting such three 
dimensional movement of the monitoring camera. 
The apparatus of the fourth embodiment shown in FIG. 5 uses two apparatuses 
of the third embodiment. A turning shaft 1a of one apparatus is so 
arranged as to be perpendicularly to a turning shaft 1b of the other 
apparatus. A stationary disk 2a of the one apparatus is secured to a 
holder 4b on a distal end of the turning shaft 1b of the other apparatus. 
Each of two apparatuses can set its monitoring range independently while 
watching a video picture picked up by the monitoring camera 5. Namely, as 
shown in FIG. 6, one monitoring range (B3) of a monitoring camera 5 is to 
be determined by turning the turning shaft 1a of one apparatus while the 
turning shaft 1b is in an unturnable state. To the contrary, the other 
monitoring range (B4) of the monitoring camera 5 is to be determined by 
turning the turning shaft 1b of the other apparatus while the turning 
shaft 1a is in an unturnable state. Incidentally, in the monitoring ranges 
(B3, B4) shown in FIG. 6, an offset of the monitoring camera 5 from the 
turning shaft 1b isn't considered. Generally, such offset is considerably 
small as compared with a distance between the monitoring camera 5 and the 
subject to be monitored. Therefore, in FIG. 6, in order to make the 
explanation of the movement of the monitoring camera 5 simple, such offset 
isn't considered. 
According to this embodiment, by means of operating both apparatuses, a 
three-dimensional movement of the monitoring camera can be obtained, 
thereby monitoring a wider field by means of a single monitoring camera. 
According to the present invention, a pair of the boundary limit angles for 
determining the range of turning of the monitoring camera can be readily 
set and changeable without the mechanical resetting or readjustment of the 
apparatus. Two or more pairs of the boundary limit angles can be readily 
set and switched over freely. Further, in the embodiments described above, 
the above settings can be carried out while watching the video picture 
picked up by the monitoring camera, and therefore the desired turning 
range can be set accurately.