Movable or removable closures – Radiant energy control
Reexamination Certificate
2002-04-26
2004-08-31
Redman, Jerry (Department: 3634)
Movable or removable closures
Radiant energy control
Reexamination Certificate
active
06782660
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an automatic door sensor. In particular, the present invention concerns measures to ensure an accurate detection operation of an object (e.g. a human body) located on the track of an automatic door, thereby enhancing the reliability of the opening and closing action of the automatic door.
Usually, with respect to an automatic door which opens and closes along a track, object detection ranges are set on the interior and the exterior of its doorway. Objects in these detection ranges are detected by an activation sensor. The activation sensor generally includes sensor mats, ultrasonic sensors and pyroelectric sensors. On detecting entry of an object into any of the detection ranges, the activation sensor performs an ON operation to open the door.
In addition to this activation sensor, an auxiliary sensor is disposed in the vicinity of the track of the door, between the interior and exterior detection ranges. As disclosed in Japanese Patent Laid-open Publication No. 2000-320243, for example, the auxiliary sensor makes use of light beams (e.g. infrared rays). Typically, the auxiliary sensor can be classified into three types.
The first type of auxiliary sensor is shown in FIG.
8
. Beam sensors are mounted on a pair of posts
94
which stand on both sides of a doorway
93
. Transmitters
95
on one of the posts are located face to face with receivers
96
on the other post (the structure in
FIG. 8
employs two beam sensors, each of which is composed of a transmitter
95
and a receiver
96
). In each sensor, when a light beam is emitted from the transmitter
95
towards the receiver
96
and interrupted by a person or the like, the receiver
96
fails to receive the light beam. The sensor regards this condition as the presence of an object near the track of doors
90
. Based on this recognition, the auxiliary sensor holds the doors
90
open, even when the activation sensor is turned off.
The second type of auxiliary sensor is shown in
FIG. 9. A
transmitter
95
and a receiver
96
are mounted at the end of a first door
91
, whereas mirrors
97
are provided at the end of a second door
92
in order to reflect the light emitted from the transmitter
95
back to the receiver
96
. Similar to the first prior art structure, when a light beam is emitted from the transmitter
95
and interrupted by a person or the like, the receiver
96
fails to receive the light beam. The sensor regards this condition as the presence of an object near the track of the doors
91
,
92
. Based on this recognition, the auxiliary sensor holds the doors
91
and
92
open, even when the activation sensor is turned off. Such an auxiliary sensor is disclosed, for example, in Japanese Patent Laid-open Publication No. H6-138253.
The third type of auxiliary sensor is shown in FIG.
10
. An ultrasonic sensor
99
is built in a transom
98
above a doorway
93
and produces ultrasonic waves to and around the track of doors
90
. In
FIG. 10
, the detection area of the ultrasonic sensor
99
is indicated by a dash-dotted line. According to this sensor, a sensor signal from the ultrasonic sensor
99
is considered valid only when the doors
90
are fully open. On the other hand, when the doors
90
are fully closed or in the course of closing, any sensor signal from the ultrasonic sensor
99
is considered invalid. This principle prohibits the sensor
99
from wrongly detecting the closing doors
90
as a person or other object. Thus, the doors
90
are not opened at unnecessary occasions. Such an auxiliary sensor is disclosed, for example, in Japanese Utility Model Laid-open Publication No. H1-112287.
However, these conventional sensors have various problems as mentioned below.
As for the first type of auxiliary sensor, the transmitters
95
and the receivers
96
are mounted on the posts
94
. Hence, this sensor is unable to direct the beams in a space vertically above the track, and may fail to detect an object which lies on the track. In other words, if an object locates at a position depicted by an imaginary line i in
FIG. 8
, the sensor cannot detect the object, which is high enough for the height position of the beams but which fails to block the beams. Furthermore, installation of the transmitters
95
and the receivers
96
involves a complicated wiring arrangement through the inside of the posts
94
. Particularly, if a plurality of beam sensor sets are employed, the wiring arrangement is extremely complex and requires higher installation costs.
The second type of auxiliary sensor is capable of directing the beam in a space vertically above the track, and thus capable of detecting an object which lies on the track. However, installation of this sensor is more complex than that of the first type of sensor, because the transmitter
95
and the receiver
96
are mounted on the door
91
, with the wiring led through the inside of the door
91
.
The third type of auxiliary sensor can solve the problems concerning the first and second types of sensors. Nevertheless, the third type of sensor may make a wrong detection, owing to a change in the floor condition (e.g. a change of the reflection factor). For example, if the floor condition turns from dry to wet due to rainfall or the like, the sensor may wrongly recognize the change of the floor condition as the entry of a person. In this case, the doors
90
are left open even when no person is present on the track of the doors
90
.
As mentioned above, none of the conventional automatic door sensors can perform fully reliable object detection operations in the vicinity of the track of the doors
90
. Therefore, there has been considerable demand for an automatic door sensor which can ensure satisfactory reliability in object detection.
The present invention is made in view of such problems and demands. An object of the present invention is to provide an automatic door sensor which can accurately detect an object located in a predetermined area which is defined on or above the track of an automatic door, thereby enhancing the reliability of the opening and closing action by the automatic door.
SUMMARY OF THE INVENTION
In order to achieve the above object, the present invention employs a pair of sensors whose detection areas cross each other on the track or in a space vertically above the track. With such sensors, the recognition of an object (e.g. a person) that in located on the track takes place when both of the sensors produce detection signals. Thus, the present invention improves reliability in an object detection operation on the track. Besides, the crossed detection areas are utilized in determining the presence or absence of an object (e.g. a person). The resulting structure is less susceptible to adverse influences which may be caused, for example, by a change of the reflection factor on the floor.
Specifically, the present invention supposes an automatic door sensor which detects the presence or absence of an object on a track of an automatic door. This automatic door sensor comprises a pair of sensor means for detecting an object and producing an object detection signal, if the object is located within a detection area of each sensor means which is defined in a surrounding area of a doorway. The detection areas of the respective sensor means partially cross each other on the track or in a space vertically above the track as viewed from an extension direction of the track. The automatic door sensor also comprises control means which is capable of receiving the object detection signal produced by each of the sensor means. This control means recognizes the presence of an object on the track and keeps the door in an open state only when the control means receives the object detection signals from both of the sensor means.
According to this feature, when an object (e.g. a person) is present on the track, it means that the object locates in a region where the detection area of one of the sensor means crosses that of the other sensor means. In this situation, object detection signals are produce
Ikeuchi Akihiro
Takada Yasuhiro
Optex Co. Ltd.
Redman Jerry
Wenderoth , Lind & Ponack, L.L.P.
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