Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2002-02-27
2004-06-29
Wu, Daniel J. (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S686100, C340S573100, C340S540000, C340S500000, C382S100000, C382S103000, C382S106000, C348S155000, C348S152000, C348S143000, C318S286000, C318S626000
Reexamination Certificate
active
06756910
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a sensor for automatic doors. In particular, the present invention concerns measures to conduct an object detection operation in a predetermined area without fail, thereby enhancing reliability of opening/closing action of automatic doors.
With respect to an automatic door which opens and closes along a track, an object detection range is usually set on an interior and an exterior of a doorway, and objects in a respective detection range are detected by an activation sensor. The activation sensor generally includes sensor mats, ultrasonic sensors and passive/active infrared sensors. On detecting entry of an object within the respective detection range, the activation sensor is turned on and operates to open the door.
In addition to the activation sensor, an auxiliary safety sensor is disposed in the vicinity of the track of the door, between interior and exterior detection ranges. As disclosed in Japanese Patent Laid-open Publication No. 2000-320243, the auxiliary safety sensor makes use of light beams (e.g. infrared rays). Typically, the auxiliary safety sensor can be classified into the three types.
A first type of auxiliary safety sensor is shown in FIGS.
6
(A) and
6
(B). FIG.
6
(A) is a front view of an automatic door and FIG.
6
(B) is a sectional view taken along line B—B in FIG.
6
(A). As illustrated, beam sensors are mounted on a pair of posts
62
,
62
which stand on both sides of a doorway
61
. Transmitters
63
,
63
on one of the posts are positioned face to face with receivers
64
,
64
on the other post. The structure in FIGS.
6
(A) and
6
(B) employs two beam sensors, each of which is composed of a transmitter
63
and a receiver
64
. In each sensor, when a light beam is emitted from the transmitter
63
towards the receiver
64
and interrupted by a person or the like, the receiver
64
fails to receive the light beam. The sensor regards this condition as presence of an object near a track of doors
65
. Based on this recognition, the auxiliary safety sensor holds the doors
65
open, even when the activation sensor is turned off.
A second type of auxiliary safety sensor is shown in FIGS.
7
(A) and
7
(B). FIG.
7
(A) is a front view of an automatic door and FIG.
7
(B) is a sectional view taken along line B—B in FIG.
7
(A). As illustrated, a transmitter
63
and a receiver
64
are mounted at an end of a first door
651
, whereas mirrors
71
,
71
are equipped at an end of a second door
652
in order to reflect light emitted from the transmitter
63
back to the receiver
64
. Similar to the first type of auxiliary safety sensor, when a light beam is emitted from the transmitter
63
and interrupted by a person or the like, the receiver
64
fails to receive the light beam. The sensor regards this condition as presence of an object near a track of the doors
651
,
652
. Based on this recognition, the auxiliary safety sensor holds the doors
651
,
652
open, even when the activation sensor is turned off. Such auxiliary safety sensor is disclosed, for example, in Japanese Patent Laid-open Publication No. H6-138253.
A third type of auxiliary safety sensor is shown in FIG.
8
. An ultrasonic sensor
82
is built in a transom
81
above a doorway
61
and produces ultrasonic waves toward and around a track of doors
65
. In
FIG. 8
, a detection area of the ultrasonic sensor
82
is defined by a dash-dotted line. According to this sensor, a sensor signal from the ultrasonic sensor
82
is considered valid only when the doors
65
are fully open. On the other hand, when the doors
65
are fully closed, or in a course of closing, any sensor signal from the ultrasonic sensor
82
is considered invalid. This principle prohibits the sensor
82
from wrongly detecting closing doors
65
as a person or other object, so that the doors
65
are not made to unnecessarily open.
However, these conventional sensors present various problems as mentioned below.
As for the first type of auxiliary safety sensor (FIGS.
6
(A) and
6
(B)), a detectable object is limited to an object which stands at or passes through a height and position where either pair of the transmitters
63
,
63
and the receivers
64
,
64
is mounted (i.e. at a height indicated by dash-dotted lines). In this case, the sensor fails to detect a small object located on the track (e.g. an object
66
depicted by an imaginary line i in FIG.
6
). Consequently, the doors
65
,
65
close as soon as the activation sensor is turned off, catching the object
66
between the doors
65
,
65
. As another problem, because the transmitters
63
,
63
and the receivers
64
,
64
are mounted on the posts
62
,
62
, it is impossible to direct light beams vertically above the track. Again, the sensor may fail to detect an object which lies on the track. In other words, if an object
67
is located at a position depicted by an imaginary line j in
FIG. 6
, the sensor cannot detect the object
67
, which is high enough for the height and position of light beams, but which fails to block the light beams. Furthermore, installation of the transmitters
63
,
63
and the receivers
64
,
64
involves a complicated arrangement of wiring through an interior of the posts
62
,
62
.
The second type of auxiliary safety sensor (FIGS.
7
(A) and
7
(B)) can direct a light beam vertically above the track, thereby being capable of detecting an object which lies on the track. However, as with the first type of auxiliary safety sensor, a detectable object is limited to an object which stands at or passes through a height and position of either of the light beams. Referring to FIGS.
7
(A) and
7
(B), the sensor fails to detect a small object
66
laid on the track, as depicted by an imaginary line i. Moreover, installation of the second type of auxiliary safety sensor is more complex than that of the first type, because the transmitter
63
and the receiver
64
of the second type are mounted on the door
651
and need to have wiring arranged through an interior of the door
651
.
The third type of auxiliary safety sensor (
FIG. 8
) solves the problem of arranging wiring through the interior of the posts
62
,
62
or the doors
65
,
65
, and thus improves installation workability. However, this sensor has a different problem, because a signal from the ultrasonic sensor
82
is invalidated as soon as the doors
65
,
65
start a closing action. Namely, once the doors
65
,
65
start to close, it is impossible to detect a person coming from an area which is not covered by the ultrasonic sensor
82
.
As mentioned above, none of the conventional sensors for automatic doors provides sufficient reliability in object detection. Therefore, there have been considerable demands for a sensor for automatic doors which can ensure satisfactory reliability with regard to object detection.
SUMMARY OF THE INVENTION
The present invention is made in view of the above problems. An object of the present invention is to provide a sensor for an automatic door which can ensure detection of an object in a predetermined area around the automatic door, thereby enhancing reliability of an opening/closing action of the automatic door.
In order to accomplish this object, the present invention intends to improve reliability of an object detection operation in the following manner. According to the present invention, image pickup means such as a CCD camera takes an image of a predetermined area around a door. From this image, a distance between the image pickup means and each object in the predetermined area is measured. Based on the measured distance, a sensor identifies presence or absence of an object which excludes a background object (e.g. a floor, a wall and the like) and the door.
A sensor for an automatic door according to a first aspect of the invention (hereinafter referrd to as Invention
1
) is composed of image pickup means, distance measurement means, object identification means and output means. The image pickup means is capable of taking an image of a predetermined area around
Imanishi Osamu
Imuro Yoshihiro
Kurata Mataichi
Ohba Hiroyuki
Nguyen Tai T.
Optex Co. Ltd.
Wu Daniel J.
LandOfFree
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