1. An elevator positioning device that detects a vertical position of a cage (1) by means of detected plates (13) installed in a shaft of an elevator that moves between a plurality of floors of a building and a sensor (12) installed on the cage (1) for detecting each of said detected plates (13) from a position opposed to said detected plate (13), wherein a maximum or a minimum of an output of said sensor (12), whose output is changed by detecting said detected plate (13), is a leveling (101) of said elevator.

2. The elevator positioning device according to claim 1 wherein an output of said sensor (12) is changed in accordance with a shape of said detected plate (13) , said detected plaLte (13) has a shape that has a cut of a triangle with a center line of a rectangular plate as an axis of symmetry so that a top and a bottom of the rectangle are parts for detecting a door zone, a vertex of the triangle is a part corresponding to the leveling of the elevator, and sides are parts for measuring a difference in the elevator floor and landing floor level.

3. The elevator positioning device according to claim 2 wherein a part for measuring a distance between said detected plate (13) and said sensor (12) is provided on said detected plate (13) for compensating for a variation component in a horizontal direction of said cage (1).

4. The elevator positioning device according to claim 3 wherein an inductive proximity sensor is used as said sensor (12).

5. The elevator positioning device according to claim 3 wherein a capacitive proximity sensor is used as said sensor (12).

6. The elevator positioning device; according to claim 1 comprising said sensor (12) whose output is changed according to a distance between a detected object and said sensor (12) which are opposed each other,- and said detected object whose distance to said sensor (12) is changed according to an amount of difference in. the elevator floor and landing floor level so that the difference can be measured.

7. The elevator positioning device according to claim 1 wherein a plurality of sensors (12) are provided and outputs of said sensors (12) are combined for measuring a difference in the elevator floor and landing floor level.

8. The elevator positioning device according to claim 2, 6, or 7 wherein the detected plate (13) is installed on a hall sill (3).

9. The elevator positioning device according to claim 8 wherein said detected plate (13) is installed L/2 apart from a center of the hall sill in a sill direction where L is a length of an apron of the cage (1) -

10. The elevator positioning device according to claim 2, 6, or 7, further comprising a device for recording the difference in the elevator floor and landing floor level.

BACKGROUND OF THE INVENTION
The present invention relates to an elevator positioning device, and more particularly to a device that detects the position of a cage in the holstway.
FIG. 7 shows the general configuration of a conventional elevator. In the conventional elevator, the position of a cage 1 that is moving in the movement direction is detected indirectly by counting the output pulse of an encoder 7 connected to an electric motor 6 that drives the cage 1. The indirect position information on the cage 1 detected in this way involves a difference from the actual position information because of the slippage or elongation of the rope. This difference is a leveling difference that is the difference between the landing floor and the elevator floor. To correct this leveling difference, a detected plate 13 called a shading plate is installed near the stop position of each floor, and a sensor 15, which detects the detected plate, is installed on the cage side. The sensor 15 detects the detected plate 13 to find the correct distance to a stop floor for use as the correction amount for controlling the stop operation of the cage 1. However, because the position information is not used as the negative feedback in the position control operation, a leveling difference is

caused by the elongation or slippage of the rope that may be generated after the correction. The technology for measuring this leveling difference is disclosed in JP-A-63-196479 that discloses the technology for measuring the conventional rhombic detected plate by means of a transformer, JP-A-8-59105 that discloses the technology based on the cam mechanism, and JP-A-2004-067252 that discloses the technology for perfoz-ming the leveling control operation only when the leveling difference exceeds a predetermined amount.
SUMMARY OF THE INVENTION
However, the conventional technology in JP-A-63-196479 does not assume the detection of the door zone in which the door can be opened or closed. In addition, because the sensor has a horseshoe shape through which the detected plate passes, the apparatus projects into the shaft with the possibility that the governor rope will get caught when an earthquake occurs. The technology in JP-A-8-59105 is intended for use in the inspection because the contact mechanism, called a cam, is used which may cause a failure during a continuous operation. The technology in JP-A-2004-067252 shows only a binary leveling difference simply indicating whether or not the leveling control is to be performed.
In addition, the conventional technology does not provide a criterion according to which installation

position of the shading plate is correctly determined and, so, the shading plate must be adjusted after temporarily installed.
First, the shading plate is installed at an approximate leveling position and, after that, the operation to stop the cage at the leveling position is performed. At this time, because the there is a difference between the landing floor level and the elevator floor level, the position of the shading plate is adjusted and the cage is moved again. The position of the shading plate is adjusted by repeating this operation so that correct leveling is attained. This adjustment operation, which is required for all floors, takes an extremely long time. In addition, because the shading plate is installed in such a way that it is combined with the sensor, a bracket is required to install the shading plate. This bracket creates another problem that, when an earthquake occurs, the governor rope will be caught by the bracket and the passengers will be confined in the elevator.
It is an object of the present invention to continuously detect a leveling difference easily using the sensor and the detected plate that are opposed each other.
It is another object of the present invention to simplify the installation of the sensor and the detected plates without cumbersome adjustment operations and to prevent the rope from being caught

when an earthquake occurs.
To accurately and continuously detect the leveling difference between an elevator cage and a hall, the present invention provides a detected plate whose shape changes with the offset in the movement direction of a sensor and provides, on a cage, a sensor whose output continuously changes according to the shape of the detected plate.
To eliminate the need for the adjustment of a shading plate and to prevent the rope from being caught, the present invention has the detected plate and the sensor opposed each other and has the detected plate installed near a hall based on the absolute positional relation with the floor.
The present invention has advantages in that the stop processing or reporting can be performed when an abnormal condition occurs when the elevator reaches a floor because the leveling difference can be measured continuously.
A simple configuration can greatly reduce the adjustment time of the positioning device and prevent the passengers from being confined in a cage due to the rope that is caught when an earthquake occurs.
In addition, use of a plurality of sensors can increase the reliability of the system against failures.
BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the general configuration of one embodiment of the present invention.
FIG. 2 is a diagram showing the operation of a first embodiment of the present invention.
FIG. 3 is a diagram showing the operation of a second embodiment of the present invention.
FIG. 4 is a diagram showing the operation of a third embodiment of the present invention.
FIG. 5 is a diagram showing the operation of a fourth embodiment of the present invention.
FIG. 6 is a diagram showing the configuration of an inductive proximity sensor.
FIG. 7 is a diagram showing the general configuration of a conventional elevator.
FIG. 8 is a diagram showing the installation positions of a detected plate and a sensor of the present invention.
FIG. 9 is an overhead view showing the installation positions of the detected plate and the sensor of the present invention.
FIG. 10 is a diagram showing other examples of the shapes of the detected plate of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
FIG. 1 is a diagram showing the general configuration of one embodiment of the present

invention. A cage 1 and a counterweight 14 are connected by a main rope 2 which is wound around a sheave 4 and a turnaround pulley 5, and the cage 1 is moved up and down in the shaft by means of an electric motor 6. In this case, though the position of the cage 1 is measured indirectly by counting the pulse of an encoder 7, the indirectly measured position information has a difference from the absolute position of the cage in the shaft due to the slippage or elongation of the main rope 2. To compensate for this difference, a sensor 12 detects a detected plate 13 and outputs the position information when the cage performs the leveling control operation. The detected plate 13 is installed on a hall sill 3 that is at the same level as the floor level of the building that is the absolute position of leveling. Unlike the configuration shown in FIG. 7, the configuration of this embodiment eliminates the need for the conversion required for the installation and has advantages in that the installation work requires less time and that there is no need for adjustment. An elevator control device 9 receives a pulse signal from the encoder 7 and a signal representing the position information obtained by the sensor 12 and the detected place 13. The elevator control device 9 controls a driving device 8 (an inverter etc.)for driving the motor 6 based on these signals. The driving device 8 drives the motor 6 based on a control signal from the control device 9 so that

the cage 1 lands or reaches a predetermined floor.
The following describes embodiments of the present invention and the operation of those embodiments. (First embodiment)
FIG. 2 shows a detected plate in a first embodiment of the present invention. The detected plate 13 is installed on the hail sill 3 that is one of objects directly corresponding to the absolute position of the floor level, and a sensor 12, which produces an output that changes with the offset in the movement direction of the cage 1 according to the shape of the detected plate 13, is installed in such a way that the sensor 12 and the detected plate 13 are opposed each other.
FIG. 8 and FIG. 9 show the actual installation positions of the sensor 12 and the detected plate 13. FIG. 8 is a diagram showing the installation positions when the cage 1 and the hall are viewed from the sides of doors 10, 11 respectively, and FIG. 9 is an overhead view of the installation positions viewed from the top of the elevator. The sensor 12 is installed on bottom of the cage 1 with its detecting surface horizontal to the movement direction of the elevator, and the detected plate 13 is installed on the hall sill with the flat plate horizontal to the movement direction of the elevator. The positional relation between the sensor 12 and the detected plate

at this time is horizontal. The sensor 12 is opposed to the detected plate 13 in the range in which the detected plate 13 can be detected, that is. in the range in which the center line of the sensor 12 in the elevator movement direction is in the projection of the detected plate 13 toward the shaft and, in that projection, the whole or a part of the sensor is included. So, the sensor 12 that is used should be the one that detects the detected plate via reflection or interference, not the one that has a horseshoe shape.
The sensor 12 and the detected plate 13, if installed in the center of the hall sill 3, could minimize the error in the accuracy of the installation on the sill. However, because an apron 701 is on the cage 1 side, the sensor 12 and the detected plate 13 are installed immediately beside the apron 701,
The detected plate 13 has a shape by which a leveling 101, that is, the leveling where the leveling difference is zero, can be identified. In addition, for the detected plate 13 to have a shape so that the leveling difference can be measured when the elevator-reaches a floor, the detected plate 13 has a notch that gives an output according to a predetermined distance from the leveling 101. In this example, a rectangular detected plate has an isosceles triangular notch so that the area of the projected portion of the sensor 12 on the detected plate 13, in the case of projecting the sensor 12 onto the detected plate existing in the

opposite direction of the sensor, changes according to the movement offset in the vertical direction. In this case, the leveling is zero when an output, signal 102S of the sensor is the minimum.
An inductive proximity sensor is used as a sensor whose output changes according to a change in the shape of a detected body. .First, the following describes the principle of operation of an inductive proximity sensor. FIG. 6 shows the configuration of an inductive proximity sensor. An inductive proximity sensor uses the high-frequency magnetic field to detect a metal (especially, a magnetized metal with a high magnetic permeability such as iron or nickel). A high-frequency oscillating circuit 502 is used to flow a high-frequency current through a coil 501 to generate a high-frequency magnetic field. At this time, if there is a metal in the magnetic field, an induced current flows on the surface of the metal, and the amplitude and the phase of high-frequency oscillation are changed by the inductance change or the heat loss of the coil. A change in the oscillation state causes a change in the output from an output circuit 503 and, based on this change, the inductance proximity sensor measures the distance between the metal and the sensor. The primary factors of the change in the output are the type of metal and the distance to the metal. That the distance to the metal causes a change in the output is equivalent to that a change in the volume of the metal

included in the high-frequency magnetic field causes a change in the output. An induced current generated by the high-frequency magnetic field is easily attenuated and flows on the surface of the metal and, in other words, a change in the area of the metal included in the high-frequency magnetic field causes a change in the output. The present invention detects the leveling of a cage by using a variation in the output caused by a change in the area of the metal in the high-frequency magnetic field.
When a capacitive proximity sensor is used, a change in the distance between, the sensor 12 and the detected plate 13 changes the capacitance if the detected plate 13 is a conductor and this change in the capacitance changes the output of the sensor 12. The capacitive proximity sensor uses the change in the output of the sensor 12 that corresponds to a change in the area of the detected plate 13 in the electric field formed by the sensor 12 and the detected plate 13.
Next, the following describes an example of the actual operation. When a cage stops, it passes the end of the detected plate 13. First, the door zone is detected. In addition, the distance to the stop position is provided as a correction for use in the stop operation control. After that, in an interval 103 of an output 10 2 of the sensor 12 through which the cage passes, the cage is moved horizontally by a distortion in the guide rail or an unbalanced load of

passengers. This is measured in the interval 103, and the horizontal distance is measured for use in correcting the measurement of the leveling difference. After that, the stop operation is performed to cause the cage to stop at the leveling 101 but a leveling difference is generated by the elongation or slippage of the rope. This is measured in. 104, that is, in the interval in which the leveling difference is output linearly.
In addition, it is also possible for a recording device (not shown) to record a leveling difference that occurs when the elevator reaches a floor for reporting a leveling error at the time it is generated.
Another effect at this time is that this embodiment can be implemented at a low cost because the configuration in which only one sensor is used is simple, the current function is satisfied, the leveling differences can be measured, and the detected plate has a simple shape to cut out. (Second embodiment)
FIG. 3 shows a detected plate in a second embodiment of the present invention. A detected plate 13, which has the shape shown, can also give the same function as that of the first embodiment and achieve the similar effect.
FIG. 10 shows other examples of the shape of the detected plate. Apparently, there are many

detected-plate shapes that maximize or minimize the output of the sensor at the leveling 101. For example, the shape of the detected plate may be a shape formed by cutting along a curved line with the leveling line as the axis of symmetry, an unsymmetrical, mountain or valley shape such as a plate shape 903, and so on. That is, the shape may be any shape that decreases in detected-plate width along the cage movement direction, reaches the minimum at the leveling, and increases in width after the minimum point is passed. (Third embodiment)
FIG. 4 shows a detected plate in a third embodiment, of the present invention. A detected plate 13 is installed on a hall sill 3 horizontally in the movement direction of the elevator, and a sensor 12 whose output changes according to the distance between the detected plate 13 and the sensor 12 is installed on the cage horizontally in the movement direction of the elevator. At this time, the positional relation between the sensor 12 and the detected plate 13 is horizontal. The detected plate 13 should have a shape by which a leveling 101, that is, the leveling where the leveling difference is 0, can be identified. The maximum of an output signal 102S of the sensor corresponds to the point where the leveling difference is 0. To allow the leveling difference; to be measured when the elevator reaches a floor, the detected plate 13 has an angle so that the output of the sensor 12

changes linearly according to the distance.
First, when the cage stops, it passes the end of the detected plate 13. At this time, the distance to the stop position is provided as a correction for the stop operation control. After that, the stop operation is performed to cause the cage to stop at the leveling 101 but a leveling difference is generated by the elongation or slippage of the rope. This is measured in 104, that is, in the interval in which the leveling difference is output linearly.
In addition, it is also possible for a recording device (not shown) to record a leveling difference that occurs when the elevator reaches a floor for reporting a leveling error at the time it is generated.
Another effect of this embodiment is that a detected object can be implemented at a low cost because the detected object 13 is only required to be bent and there is no need for notching. (Fourth embodiment)
FIG. 5 shows a detected plate in a fourth embodiment of the present invention. Sensors 12 are arranged in array and installed on the cage 1 horizontally in the movement direction of the elevator. A detected plate 13 is installed on a hall sill 3 horizontally in the movement direction of the elevator. The positional relation between the sensors 12 and the detected plate 13 is horizontal.
In this embodiment, the leveling 101 and the leveling difference are measured by a combination of outputs of the sensors 12. An increase in the number of sensors increases detection accuracy.
Another effect is that a failure in the sensors does not result in a serious fault of the system because the detection can be performed even if a part of the sensors fail.

CLAIMS:
1. An elevator positioning device that detects a
vertical position of a cage (1) by means of detected
plates (13) installed in a shaft of an elevator that
moves between a plurality of floors of a building and a
sensor (12) installed on the cage (1) for detecting
each of said detected plates (13) from a position
opposed to said detected plate (13), wherein a maximum
or a minimum of an output of said sensor (12), whose
output is changed by detecting said detected plate
(13), is a leveling (101) of said elevator.
2. The elevator positioning device according to claim 1 wherein an output of said sensor (12) is changed in accordance with a shape of said detected plate (13) , said detected plaLte (13) has a shape that has a cut of a triangle with a center line of a rectangular plate as an axis of symmetry so that a top and a bottom of the rectangle are parts for detecting a door zone, a vertex of the triangle is a part corresponding to the leveling of the elevator, and sides are parts for measuring a difference in the elevator floor and landing floor level.
3. The elevator positioning device according to claim 2 wherein a part for measuring a distance between said detected plate (13) and said sensor (12) is provided on said detected plate (13) for compensating for a variation component in a horizontal direction of said cage (1).

4. The elevator positioning device according to claim 3 wherein an inductive proximity sensor is used as said sensor (12).
5. The elevator positioning device according to claim 3 wherein a capacitive proximity sensor is used as said sensor (12).
6. The elevator positioning device; according to claim 1 comprising said sensor (12) whose output is changed according to a distance between a detected object and said sensor (12) which are opposed each other,- and said detected object whose distance to said sensor (12) is changed according to an amount of difference in. the elevator floor and landing floor level so that the difference can be measured.
7. The elevator positioning device according to claim 1 wherein a plurality of sensors (12) are provided and outputs of said sensors (12) are combined for measuring a difference in the elevator floor and landing floor level.
8. The elevator positioning device according to claim 2, 6, or 7 wherein the detected plate (13) is installed on a hall sill (3).
9. The elevator positioning device according to claim 8 wherein said detected plate (13) is installed L/2 apart from a center of the hall sill in a sill direction where L is a length of an apron of the cage
(1) -
10. The elevator positioning device according to
claim 2, 6, or 7, further comprising a device for recording the difference in the elevator floor and landing floor level.