JPH11311214A - Position detecting device for cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position detecting device for cylinders, which can display an optimum operation range and allowable operation range in distinction from each other, equalize both ranges and broaden detection ranges without increasing designing time and costs using an existing magnetic sensor. SOLUTION: This two color light emission display type position detecting device comprises two magnetic sensors MR1 and MR2 having two magnetic resistance elements respectively, four voltage comparators COM1-COM4 to compare output signal and reference voltage, a two input type logic circuit OR1 for logically calculate output signals, four input type logic circuit OR2 for logically calculating the output signals from a voltage comparator and two input type exclusive 'OR' circuit EXOR for logically calculating the output signals from an 'OR' circuit. Through this constitution, as green LED can be turned ON by the optimum operation range display signal from the 'OR' circuit OR1, and a red LED can be turned ON by the allowable operation range display signal from the exclusive 'OR' circuit EXOR.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit technology of a cylinder position detecting device for a two-color light emitting display, and more particularly, to a display in which an optimum operating range and an allowable operating range are distinguished from each other, the two ranges are almost equal, and the detecting range is substantially equal. The present invention relates to a technique that is effective when applied to a cylinder position detecting device capable of increasing the width.

[0002]

2. Description of the Related Art For example, as a technique studied by the present inventor, in a cylinder position detecting device of a two-color light emitting display, in order to detect a position of a piston on which a magnet is mounted, the cylinder is moved in the sliding direction of the cylinder. Two magnetic sensors are arranged at different positions, and the output signals of these magnetic sensors are logically operated to generate an optimum operation range display signal and an allowable operation range display signal, and the green LED is turned on to indicate the optimum operation range. However, a technique of displaying an allowable operation range by lighting a red LED is used.

In such a cylinder position detecting device, the voltage level of the output signal from the magnetic sensor may fluctuate due to the influence of an external magnetic field or the like. Between the voltage level of the output signal and the voltage level of the reference voltage, a large margin is taken to some extent, without malfunction.
It is necessary to properly display the optimum operation range and the allowable operation range.

For example, JP-A-8-145611, JP-A-8-145612, and JP-A-8-145.
In the technology described in Japanese Patent Application Laid-Open No. 613 and Japanese Unexamined Patent Application Publication No. Hei 8-152301, the waveform of the output signal from the magnetic sensor is changed by devising the shape and pitch of the pattern of the magnetoresistive element incorporated in the magnetic sensor. A position detection device capable of setting the detection range between the optimum operation range and the allowable operation range to the same size to prevent malfunction due to an external magnetic field or the like and setting the appropriate optimum operation range and the allowable operation range. Proposed.

[0005]

However, in the position detecting device described in the above publication, it is necessary to change the shape, pitch and the like of the pattern of the magnetoresistive element. It is necessary to re-create a new magnetoresistive element and further a magnetic sensor in accordance with the installation environment of a cylinder to be used, and this may lead to an increase in design time and an increase in cost.

Therefore, an object of the present invention is to distinguish and display an optimum operation range and an allowable operation range without increasing design time and cost using an existing magnetic sensor, and to make the two ranges substantially equal. Another object of the present invention is to provide a cylinder position detecting device capable of widening a detection range.

[0007]

A position detecting device for a cylinder according to the present invention is arranged so as to be displaced from each other in a sliding direction of a cylinder, and an X-axis direction of a magnetic field formed by a magnet attached to a piston. A first and a second magnetic sensor having two magnetoresistive elements whose electric resistance changes according to a magnetic flux density in the Y-axis direction, and a magnetic sensor which detects the magnetic flux density in the X-axis direction of the magnetic field and outputs the detected magnetic flux density. A first OR circuit which receives the first and second signals as inputs, performs a logical operation on these signals and outputs an optimum operation range display signal, and detects the magnetic flux density of the magnetic field in the Y-axis direction by using these magnetic sensors. The third and fourth signals output from the first and second
And a second OR circuit that performs a logical operation on these signals to output a position detection signal, and an optimum operation range display signal and a position detection signal as inputs, and performs a logical operation on these signals. An exclusive-OR circuit that outputs an allowable operating range display signal, and first and second display means that display the optimum operating range and the allowable operating range by receiving the optimum operating range indicating signal and the allowable operating range indicating signal, respectively. And

Therefore, according to the cylinder position detecting device, the optimum operating range and the allowable operating range are displayed separately by using the existing magnetic sensor without increasing the design time and cost. And the detection range can be widened. As a result, in setting the cylinder position detecting device, etc., this setting is facilitated,
In addition, the setting accuracy can be ensured, and the detection accuracy of the optimum operation range and the allowable operation range deviated from the optimum operation range can be improved. In particular, the reference voltage for setting the pulse width based on the first, second, third, and fourth signals in order to make the optimum operation range substantially equal to the allowable operation range is equal to the first magnetic sensor and the second magnetic sensor. It is desirable that the distance be set in relation to the distance from the magnetic sensor.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing a cylinder position detecting device according to an embodiment of the present invention, and FIG. 2 is a schematic sectional view showing a mounting state of the cylinder position detecting device and the cylinder in the present embodiment. FIG. 3 is an explanatory view showing the magnetic sensor, and FIG. 4 is a waveform chart showing the operation of the cylinder position detecting device.

First, the configuration of the cylinder position detecting device of the present embodiment will be described with reference to FIG.

The cylinder position detecting device according to the present embodiment is, for example, a two-color light-emitting display position detecting device that displays the optimum operating range and the allowable operating range separately, and has two magnetoresistive elements. Magnetic sensor MR1,
Four voltage comparators COM1 to COM4 for comparing MR2 with output signals from the respective magnetic sensors MR1 and MR2 and a reference voltage.
OM4, a two-input OR circuit OR1 that performs logical operation on output signals from the voltage comparators COM1 and COM3, and a four-input OR circuit OR2 that performs logical operation on output signals from the four voltage comparators COM1 to COM4. , OR circuit OR
It is composed of a two-input exclusive-OR circuit EXOR that performs a logical operation on the output signals of the OR1 and OR2, and outputs an optimum operation range display signal, an allowable operation range display signal, and a position detection signal.

Each of the two magnetic sensors MR1 and MR2 has a magnetoresistive element whose electric resistance changes according to a magnetic flux density in the X-axis direction of a magnetic field formed by a magnet attached to a piston, and a magnetic flux density in the Y-axis direction of the magnetic field. A high-current side of the output signal is output by detecting the magnetic flux density in the X-axis direction of the magnetic field, and a low-level side is Y of the magnetic field.
The output is obtained by detecting the magnetic flux density in the axial direction.

Further, two magnetic sensors MR1 and MR2
For example, as shown in FIG. 2, in order to detect the position of the magnet 3 of the piston 2 that slides in the cylinder 1, they are arranged so as to be shifted from each other in the sliding direction of the cylinder 1. As the magnetic sensors MR1 and MR2, general existing ones are used. The patterns 4 and 5 of the magnetoresistive elements in the magnetic sensors MR1 and MR2 are, for example, as shown in FIG. The shape is such that the electric resistance changes depending on the magnetic flux density in the axial direction.

The four voltage comparators COM1 to COM4 are:
The output signals from the magnetic sensors MR1 and MR2 are respectively input, the input signal is compared with a high-level or low-level reference voltage, and the comparison result is output as an output signal. Among them, the voltage comparator COM1 receives the output signal from the magnetic sensor MR1 as the input of the positive input terminal and compares the output signal with the high-level reference voltage Vh. Also, the voltage comparator C
The OM2 receives the output signal from the magnetic sensor MR1 as an input of the negative input terminal and compares the output signal with the low-level reference voltage Vl. Similarly, the voltage comparators COM3 and COM4 receive the output signal from the magnetic sensor MR2 as a positive input terminal or a negative input terminal, respectively, and are compared with the high-level reference voltage Vh or the low-level reference voltage Vl.

The OR circuit OR1 has a voltage comparator COM1.
, And the output signal of the voltage comparator COM3, the logical sum of the two input signals is output, and the result of the operation is output as an output signal. This OR circuit OR1
Output an optimum operation range display signal.

The OR circuit OR2 has four voltage comparators C
With the output signals of OM1 to COM4 as inputs, a logical OR operation is performed on these four input signals, and the operation result is output as an output signal. This OR circuit OR2 outputs a position detection signal.

The exclusive OR circuit EXOR receives the output signals of the OR circuits OR1 and OR2 as inputs, performs an exclusive OR operation on the two input signals, and outputs the operation result as an output signal. The exclusive OR circuit EXOR outputs an allowable operation range display signal.

The position detecting device configured as described above,
For example, a green LED 6 shown in FIG. 2 is turned on by receiving an optimum operation range display signal output from the OR circuit OR1. By turning on the green LED 6, the optimum operation between the piston 2 in the cylinder 1 and the position detecting device is performed. The red LED 7 is illuminated by displaying the range and inputting the allowable operation range display signal output from the exclusive OR circuit EXOR, and the illumination of the red LED 7 causes the position between the piston 2 in the cylinder 1 and the position detecting device. Is displayed.

Further, this position detecting device includes, for example, two magnetic sensors MR1, MR having two magnetoresistive elements.
2 are formed on one chip 8, and four voltage comparators COM1 to COM4, two OR circuits OR1, OR2
The exclusive OR circuit EXOR is also formed on one chip 9, and these two chips 8, 9 are mounted on a substrate 10 and integrally molded and embedded in a synthetic resin case 11. A configuration is also considered possible.

Next, the operation of this embodiment will be described with reference to the waveform diagram of FIG. 4 while referring to the circuit diagram of FIG. 1 and the operation of the position detecting device accompanying the sliding of the piston 2 in the cylinder 1. I do.

This position detecting device is attached to a predetermined position of a cylinder 1 and detects a magnetic field of a magnet 3 attached to a piston 2 sliding in the cylinder 1 by two magnetic sensors MR1 and MR2. The position detection of the stroke end of the piston rod can be displayed in the optimum operation range and the allowable operation range. For example, in FIG. 4, the cylinder 1 and the magnetic sensors MR1 and MR2 shown in FIG.
2 shows an example in which the piston 2 slides from the right direction to the left direction.

First, when the piston 2 slides from right to left, the magnetic field formed by the magnet 3 of the piston 2 is detected in the order of the magnetic sensor MR1 and the magnetic sensor MR2. At this time, the magnet 3 approaches and the output signal a of the magnetic sensor MR1 that first detects the magnetic field of the magnet 3 is shown in FIG.
(a), followed by two magnetic sensors MR1, M
The output signal b of the magnetic sensor MR2 for detecting the magnetic field of the magnet 3 at the time interval between R2 is as shown in FIG. The high level side of each of the output signals a and b detects and outputs the magnetic flux density in the X-axis direction of the magnetic field, and the low level side detects and outputs the magnetic flux density in the Y-axis direction.

Further, the output signals a and b from the magnetic sensors MR1 and MR2 are input and the voltage comparator CO
M1 compares the output signal a from the magnetic sensor MR1 with the high-level reference voltage Vh. FIG. 4 (c) shows the output signal c of the comparison result.
A signal of a high voltage level "1" is obtained at a reference voltage Vh or more based on detection of the magnetic flux density in the axial direction. Also, the voltage comparator COM
2 compares the output signal a from the magnetic sensor MR1 with the low-level reference voltage Vl. Output signal d of this comparison result
Is as shown in FIG. 4 (d), and this output signal d is a signal of a high voltage level "1" at a reference voltage Vl or less by detecting the magnetic flux density of the magnetic field in the Y-axis direction.

Similarly, the voltage comparator COM3 compares the output signal b from the magnetic sensor MR2 with the high-level reference voltage Vh. The output signal e of the comparison result is as shown in FIG. 4 (e). The output signal e becomes a signal of the high voltage level "1" at the reference voltage Vh or more by detecting the magnetic flux density of the magnetic field in the X-axis direction. Further, the voltage comparator COM4 compares the output signal b from the magnetic sensor MR2 with the low-level reference voltage Vl. The output signal f of the comparison result is as shown in FIG. 4 (f). The output signal f is a signal of a high voltage level "1" at a reference voltage Vl or less by detecting the magnetic flux density of the magnetic field in the Y-axis direction. Note that the high-level and low-level reference voltages Vh,
Vl is set so as to make the optimum operation range and the allowable operation range substantially equal in relation to the interval between the magnetic sensors MR1 and MR2.

Subsequently, four voltage comparators COM1-CO
The output signals c to f of M4 are input, and the OR circuit OR2
Performs a logical OR operation on these four input signals. The output signal g of this operation result is as shown in FIG. 4 (g). The output signal g is an output signal obtained by detecting the magnetic flux density of the magnetic field from the four voltage comparators COM1 to COM4 in the X-axis direction and the Y-axis direction. c
To f, which is a position detection signal. This position detection signal is used as a control signal of a control device such as an electromagnetic valve driven in association with the cylinder 1, for example.

Similarly, two voltage comparators COM1, CO
The output signals c and e of M3 are input and the OR circuit OR1
Performs a logical OR operation of these two input signals. FIG. 4 (h) shows an output signal h of this calculation result. The output signal h is obtained by detecting output signals c and e obtained by detecting the magnetic flux density in the X-axis direction of the magnetic field from the two voltage comparators COM1 and COM3. It becomes the optimal operating range display signal that was input. This optimum operation range display signal is used, for example, for lighting the green LED 6,
By illuminating the green LED 6, the optimum operating range between the piston 2 in the cylinder 1 and the position detecting device can be displayed.

The exclusive OR circuit EXOR receives the output signal h of the OR circuit OR1 and the output signal g of the OR circuit OR2, and performs an exclusive OR operation on the two input signals. The output signal i of this operation result is as shown in FIG. 4 (i). This output signal i is an allowable signal which receives the optimum operating range display signal from the OR circuit OR1 and the position detection signal from the OR circuit OR2. It becomes the operation range display signal. The permissible operation range display signal is used, for example, for lighting the red LED 7.
The allowable operating range between the piston 2 in the inside and the position detecting device can be displayed.

As described above, when the position detecting device is mounted at a predetermined position of the cylinder 1, the magnet 3 mounted on the piston 2 is connected to the two magnetic sensors MR1 and MR2.
And the detection of the position of the stroke end of the piston rod can be indicated by the lighting of the green LED 6 and the red LED 7, so that the mounting position of the position detecting device is in the optimum operation range or the side of this optimum operation range. Is within the allowable operation range.

Therefore, according to the cylinder position detecting device of the present embodiment, the two magnetic sensors MR1 and MR2 having two magnetoresistive elements and the magnetic sensors MR1 and MR2 are provided.
Four voltage comparators COM1 which process the output signals from
To COM4, two OR circuits OR and OR2, and an exclusive OR circuit EXOR.
Since the ED 6 is turned on and the red LED 7 can be turned on by the permissible operation range display signal from the exclusive OR circuit EXOR, the optimum operation range and the permissible operation range can be distinguished and displayed. Further, since the general existing magnetic sensors MR1 and MR2 are used, there is no increase in design time and cost.

Further, two magnetic sensors MR1 and MR2
, The logical operation of the output signal from the first magnetic sensor makes it possible to make the optimum operation range and the allowable operation range substantially equal to each other and to make the detection range wider than in the case of using one magnetic sensor. For example, two magnetic sensors MR1 and MR2
In the case where the distances are arranged at about 1.5 to 2.0 mm, the optimum operation range and each allowable operation range on the side of the optimum operation range can be uniformly extended to about 3.0 mm. . As a result, the setting of the position detecting device can be facilitated, the setting accuracy can be secured, and the detection accuracy of the optimum operation range and the allowable operation range deviated from the optimum operation range can be improved.

The present invention is not limited to the above embodiment, and it goes without saying that various changes can be made without departing from the spirit of the present invention. For example, for an LED that displays the optimum operation range and the allowable operation range separately,
The color is not limited to green and red, but may be any combination of other colors such as yellow, orange, and blue as long as two colors can be emitted.

[0033]

According to the present invention, a magnetic sensor having a magnetoresistive element whose electric resistance changes according to the magnetic flux density in the X-axis direction and the Y-axis direction of the magnetic field, and the X-axis direction and the Y-axis Optimum operating range and allowable operating range by using an existing magnetic sensor without increasing design time and cost by having an OR circuit that detects the magnetic flux density in the direction and performs logical operation on the output signal Can be distinguished from each other so that both ranges are substantially equal and the detection range can be widened.

As a result, in the cylinder position detecting device of the two-color light emitting display, the lighting region of the optimum operating range and the lighting region of the allowable operating range can be equally and extended, so that the setting of the position detecting device is facilitated and the setting is facilitated. Accuracy can be ensured, and the detection accuracy of the optimum operation range and the allowable operation range deviated from the optimum operation range can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a cylinder position detecting device according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a mounting state of a cylinder position detecting device and a cylinder in one embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a magnetic sensor in one embodiment of the present invention.

FIG. 4 is a waveform chart showing an operation of the cylinder position detecting device in one embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 cylinder 2 piston 3 magnet 4,5 pattern 6 green LED 7 red LED 8,9 chip 10 substrate 11 case MR1, MR2 magnetic sensor COM1-COM4 voltage comparator OR1, OR2 OR circuit EXOR exclusive OR circuit

Claims (2)

[Claims] An electric resistance is changed according to a magnetic flux density in an X-axis direction and a Y-axis direction of a magnetic field formed by a magnet attached to a piston. A first and a second magnetic sensor having a magnetoresistive element; and a first and a second signal which are output by detecting the magnetic flux density of the magnetic field in the X-axis direction by the first and the second magnetic sensors. A first logical sum circuit that performs a logical operation on these signals to output an optimum operation range display signal, and detects and outputs a magnetic flux density of the magnetic field in the Y-axis direction by the first and second magnetic sensors. A second OR circuit which receives the third and fourth signals and the first and second signals to perform a logical operation on these signals and outputs a position detection signal; A signal and the position detection signal An exclusive-OR circuit that performs a logical operation on these signals to output an allowable operation range display signal; and an optimum operation range and an allowable operation A first and second display means for displaying a range, comprising: a cylinder position detecting device; 2. The position detecting device for a cylinder according to claim 1, wherein said first, second, third, and fourth signals are used to make said optimum operation range substantially equal to said allowable operation range. The reference voltage for setting the pulse width based on
The cylinder position detecting device is set in relation to an interval between the magnetic sensor and the second magnetic sensor.