JPH1130502A - Position detecting mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a high density position detection possible to be carried out at a low cost, by installing a magnet at a moving part and also installing a plurality of Hall elements for magnet-proximity detection along the moving range. SOLUTION: Immediately after the power supply of an apparatus is turned on, a control part 7 confirms the state of respective Hall elements 5a, 5b, 5c. When, e.g. the Hall element 5b is in an ON state, the control part 7 judges that a moving part 3 is situated in the center. When the control part 7 judges that all the Hall elements 5a to 5c are in an OFF state, the control part 7 sends out pulses to a pulse motor 1, it moves the moving part 3, and it confirms that the state of the respective Hall elements 5a, 5b, 5c is changed. For example, when the moving part 3 is situated between the Hall elements 5b, 5c, the Hall element 5b is soon set to an ON state, and it is detected that the moving part 3 is situated in the center. When the moving part 3 is situated between the Hall elements 5a, 5b, the Hall element 5a is soon sent to an ON state, and it is detected that the moving part 3 is situated at the shaft end on the side of the pulse motor 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting mechanism, and more particularly to a position detecting mechanism used for an apparatus having a moving mechanism combining moving axes, such as a mounter and a plotter.

[0002]

2. Description of the Related Art As a position detecting mechanism such as a mounter or a plotter having a pulse motor or the like, a micro switch or a photo sensor is installed at an end of each axis, and a position where each sensor is turned on / off is defined as a mechanical origin.
A mechanism that calculates the moving distance from the number of pulses sent to the pulse motor from that position and detects the relative position; A linear scale such as a magnet scale is installed on each axis, and the absolute position is determined by the read value. Detecting mechanism: A recognition mark is placed on a movable part, and ITV (industria
l television) A mechanism for recognizing a position by image recognition using a camera or the like; a mechanism for arranging a measurement target on a movable part and directly measuring a distance using a laser sensor or the like;

[0003]

The above-mentioned mechanism can be realized inexpensively and is generally used. However, since the sensors are arranged at the ends of the respective shafts, the movable range is reduced accordingly. If it is necessary to stop the power supply to a pulse motor or the like due to some trouble, the origin return operation (moving to the end of each axis at an extremely constant speed) is required because the origin position for position recognition cannot be known. Operation to detect a mechanical origin position by a sensor).

[0004] As for the above, since the sensor is arranged outside the movable range, the whole apparatus becomes large. Also, the sensors themselves are expensive.

[0005]

SUMMARY OF THE INVENTION The present invention comprises a movable part operating in a predetermined movable range and a drive part for driving and moving the movable part, and detects the position of the movable part at an arbitrary position. In the position detection mechanism to perform, a magnet is provided on the movable part,
It is characterized in that a plurality of Hall elements are arranged at intervals from each other along the movable range and detect the proximity of the magnet of the movable part.

In addition, when a certain Hall element detects that the magnet of the movable part is approaching, it is determined that the movable part is located at the position of the Hall element, and any Hall element is determined to be movable. When the proximity of the magnet is not detected, a control unit is provided that controls the driving unit to move the movable unit until one Hall element detects the proximity of the magnet of the movable unit. .

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing an embodiment. In the figure, reference numeral 1 denotes a pulse motor as a drive unit, which is connected to a drive screw 2 and moves the movable unit 3 in the left and right direction in the figure. Reference numeral 4 denotes a magnet, which is incorporated in the movable unit 3. 5 (a, b, c) is a Hall element,
Here, an example using three is shown, but any number and arrangement may be used as needed. In the example of FIG. 1, the Hall elements 5
a and 5c, and a Hall element 5 is provided at the center of the movable range.
b is installed.

Reference numeral 7 denotes a control unit which is connected to the Hall elements 5 to control them, and is connected to the pulse motor 1 to generate pulses required for driving. The operation will be described below. First, immediately after the power of the apparatus is turned on, the apparatus is in a state where it does not recognize the position of the movable unit 3, and it is necessary to perform position detection to operate the apparatus. The control unit 7 checks the state (ON or OFF) of each of the Hall elements 5a, 5b, 5c. At this time, for example, if the Hall element 5b is in the ON state, the control unit 7 determines that the movable unit 3 is located at the center. (In this example, the state in which the magnetic flux density is detected by the magnet 4 in which the Hall element is incorporated in the movable portion 3 is set to the ON state.) All the Hall elements 5
When the control unit 7 determines that a, 5b, and 5c are in the off state, the control unit 7 sends a pulse to the pulse motor 1 to move the movable unit 3, and the respective Hall elements 5a, 5b,
Confirm the change of the situation of 5c.

Here, considering the case where the movable section 3 moves toward the pulse motor 1, the movable section 3 is provided with the Hall elements 5b and 5b.
When the movable element 3 is located between the hall elements 5a and 5b, the Hall element 5b is turned on. Eventually, it is turned on, and it is detected that the movable part 3 is at the shaft end on the pulse motor 1 side.

In the position detection mechanism using three Hall elements 5 as in the above-described example, the position can be detected only by moving at most one half of the movable range, and the movement required for returning to the origin is required. The distance can be shortened, and accordingly, the time required for operation becomes shorter. In addition, since the Hall element 5 itself is inexpensive, it is possible to further reduce the moving distance and time by arranging more Hall elements 5.

Since the Hall elements 5 can be arranged within the movable range, a plurality of Hall elements 5 can be arranged without reducing the movable range. Further, since the Hall element 5 is small and lightweight, it can be installed in a small gap, and it is possible to reduce the size of the device at low cost. Further, the position can be detected each time the movable section 3 passes through the portion where the Hall element 5 is arranged during the operation of the apparatus, so that the correction can be performed if necessary, and the Hall element 5 itself has environmental resistance ( (The operating temperature range is wide), so that the present invention can be applied to a device that is used in a high-temperature or low-temperature environment.

In the above example, the position detection mechanism for one axis has been described. However, when there are a plurality of axes that move linearly, a Hall element is added to each axis, and It is possible to detect the position. For example, since the XY plotter has two axes, if three Hall elements are arranged on the X axis and three places on the Y axis, three positions can be detected on each axis. It is possible to set nine detection positions. Thus, the number of detection positions is the product of the number of Hall elements arranged on each axis.

The movable range is not limited to a straight line, but may be a curve or a curved surface.

[0014]

As described in detail above, since the magnetic flux density of the magnet provided in the movable portion is detected by the Hall element, the movable area can be reduced by disposing the Hall element within the movable range. It is possible to arrange a plurality of devices without performing the above operation, which has the effect of realizing the miniaturization of the device.

The arrangement of a plurality of Hall elements has the effect of reducing the distance and time required to move the movable part for position detection. Furthermore, since the Hall element is inexpensive, there is an effect that high-density arrangement is possible at low cost.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Driving part 3 Movable part 4 Magnet 5a, 5b, 5c Hall element 7 Control part

 ──────────────────────────────────────────────────の Continuing from the front page (72) Katsuhide Sakai, Oki Electric Industry Co., Ltd., 1-7-12 Toranomon, Minato-ku, Tokyo

Claims (2)

[Claims] 1. A position detecting mechanism for detecting a position of a movable portion at an arbitrary position, comprising: a movable portion that operates in a predetermined movable range; and a drive portion that drives and moves the movable portion. A position detecting mechanism, comprising: a plurality of Hall elements that are arranged at intervals from each other along a movable range and that detect the proximity of the magnet of the movable part. 2. A method according to claim 1, wherein when a certain Hall element detects that the magnet of the movable section is close to the movable element, it is determined that the movable section is located at the position of the Hall element.
If none of the Hall elements detects the proximity of the magnet in the movable section, a control section is provided to control the drive section to move the movable section until one Hall element detects the proximity of the magnet in the movable section. A position detecting mechanism.