JPS62106303A - Position detector - Google Patents

Abstract

PURPOSE:To obtain high resolving power equal to or more than a magnetizing pitch, by providing a position detecting head having a plurality of electromagnetic converter elements arranged at a predetermined pitch in opposed relation to a magnet magnetized at a constant pitch and using positional signals having two or more phases obtained by relatively moving said head with respect to said magnet. CONSTITUTION:A position detector used in a machine tool such as an automatic lathe is constituted of a magnet 1 magnetized at a constant pitch and a position detecting head 9 moved in parallel to said magnet 1 or allowed to be spaced apart therefrom. In this constitution, the head 9 is constituted of four magneto- resistance elements 5-8 spaced apart from each other at a pitch P2 1/4 the magnetizing pitch P1 of the magnet 1 and, if this head 9 is allowed to be spaced apart with respect to the magnet 1 as shown by arrows (c), (d), the resistance value to a magnetic field shows the max. value and, if moved in parallel to the magnet as shown by arrows (e), (f), the resistance value shows the min. value. By this constitution, a power source 16 receiving the supply of DC voltage is connected to the middle point between terminals 5a, 6a and terminals 7a, 8a are earthed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a position detection device suitable for use in various machine tools such as automatic lathes.

[Summary of the invention]

The present invention provides a positioning device suitable for use in various machine tools such as automatic lathes, which includes a magnet magnetized at a constant pitch and a plurality of magnets arranged at a predetermined pitch relative to the pinch of the magnet. A position detection head that has a magnetoelectric transducer and moves relative to the magnet and outputs position signals of two or more phases corresponding to the position on the magnet is provided, and the position detection head counts the position signals and detects a predetermined position on the magnet. A count signal specifying the interval is obtained, a desired phase position signal is selected from two or more phase position signals, and the position of the position detection head with respect to the magnet is detected using the count signal and the analog value of the desired phase position signal. By doing so, we have made it possible to detect minute displacements that are less than the magnetization pitch, so that so-called dead zones do not occur, and we have made it possible to perform high-resolution position detection that is greater than the resolution determined by the magnetization pitch. It is something.

[Conventional technology]

Generally, as a position detection device used in various machine tools such as automatic lathes, the main part is shown in FIG. 8A.

In this Figure 8A, (1) shows a magnet in which N and S poles are arranged at a constant pitch, and this magnet name is H1l.
The magnetic head for position detection (
2), and this position detection magnetic head is movable in the directions of arrows a and b.

In the position detection device whose main parts are configured in this way, when the position detection magnetic head (2) is moved, as shown in FIG.
As shown in Figure 3, the output signal (3) has a maximum absolute value at a position corresponding to the boundary of the magnetized pattern of the magnet (1).
) can be obtained.

Therefore, in the position detection device of this example, the output signal (3) obtained in this way is counted for each peak using a predetermined counter (not shown) with a predetermined position as a reference. Magnet (1) on head (2)
The position relative to the object can be detected.

[Problem that the invention seeks to solve]

However, in such a conventional position detection device, the position of the position detection magnetic head (2) with respect to the magnet (1) is detected by counting the number of peaks of the output signal (3) as shown in FIG. 8B. Therefore, there is a so-called dead zone between the peaks of the output signal (3), making it impossible to detect the position. Therefore, in order to realize high-resolution position detection in such conventional position detection devices, the magnetization pitch must be made very fine, but in this case, in order to obtain a good output signal, the position detection head ( The gap between the magnet (2) and the magnet (1) must also be made very narrow, and the magnetization pitch is therefore limited to about 0.1 square. For this reason, high-resolution position detection cannot be performed, and when position servo is to be applied, there is a dead zone in areas below the resolution, making it very difficult to apply servo.

In view of this, an object of the present invention is to provide a position detection device that can obtain a resolution higher than that determined by the magnetization pitch of the magnet (1).

[Means for solving problems]

As shown in FIGS. 1 and 2, the position detection device according to the present invention includes a magnet (1) magnetized with a certain pinch and a magnet (1) arranged at a predetermined pinch with respect to the pitch of the magnet (1). A plurality of magnetoelectric transducers (5) (6) (7) (
A position detection head (9) is provided, which has a position detection head (9) which has a position detection head (9) that moves relative to the magnet (1) and outputs a position signal of two or more phases corresponding to the position on the magnet (1). Count to obtain a count signal that specifies a predetermined section on the magnet throat, select a desired phase position signal from two or more phase position signals, and use the count signal and the analog value of the desired phase position signal to apply a signal to the magnet. The position of the position detection head is detected.

[Effect]

According to the present invention, the position signals output from the position detection head (9) are counted to obtain a count signal specifying a predetermined section on the magnet (11), and a desired phase is detected from position signals of two or more phases. The position signal of the desired phase is selected, and the position of the position detection head (9) relative to the magnet (1) is detected using the second count signal and the analog value of the position signal of the selected desired phase. It is possible to detect minute displacements that are less than the pitch, and to perform position detection with a higher resolution than that determined by the magnetization pitch.

〔Example〕

Hereinafter, one embodiment of the position detection position of the present invention will be described with reference to FIGS. 1 to 7. In this example, the magnet (1) is fixed and the position detection head (9) is connected to the magnet (
1) The case of moving to a desired position will be explained.

In FIG. 1, (1) shows a magnet in which N and S poles are arranged at a predetermined pitch P1 similar to that shown in the conventional example in FIG.
and a position detection head (
9). In this example, this position detecting head (9) is composed of four magnetoresistive elements+5 as shown in FIG.
) (6) (7) (Constructed with 81. In this case, the pitch P2 between the magnetoresistive elements is arranged to be one quarter of the magnetization pitch P1 of the magneto-node (1), and arrows C and d The resistance value becomes the maximum value for the magnetic field in the direction of arrow e
It is arranged so that the resistance value becomes the minimum value with respect to the magnetic field in the direction of and f. Further, one terminal (5) of the first magnetoresistive element (5)
a) and one terminal (6a) of the second magnetoresistive element (6)
and the middle point of this connection is connected to a power supply terminal (16) to which DC voltage is supplied. Further, the other terminal (5b) of the first magnetoresistive element (5) and one terminal (7a) of the third magnetoresistive element (7) are connected, and the midpoint of this connection is connected to one output terminal (17). ). Further, the other terminal (6) of the second magnetoresistive element (6)
b) and one terminal (8a) of the fourth magnetoresistive element (8)
and connect the middle point of this connection to the other output terminal (1
8). In addition, a third magnetoresistive element (7
) is connected to the other terminal (8b) of the fourth magnetoresistive element (8), and the middle point of this connection is connected to the ground terminal (19).

In the position detection node (9) configured in this manner, a predetermined DC voltage is supplied to the power supply terminal (16) and the ground terminal (19) is grounded as shown in FIG. When the throat (9) is moved in the direction of arrow a to detect the position as shown in Figure A, a sine wave output signal SA as shown in Figure 2B is obtained at one output terminal (17), and the other A sine wave output signal SB as shown in FIG. 2C is obtained at the output terminal (18).

Therefore, in this example, as shown in Fig. 1, one output terminal (17) of the position detection head (9) is connected to the input side of one offset-adjusted amplifier (20), and the position detection head is connected to the output side of the input side of one amplifier (20). A signal SA is obtained by amplifying the sine wave signal SA obtained at one output terminal (17) of (9), and the output side of one amplifier (20) is connected to the amplitude adjustment circuit (21).
, so that a sine wave signal SA whose amplitude is adjusted to a predetermined value is obtained at its output side. Also, the amplitude adjustment circuit (
21) are connected to the respective input sides of one non-inverter (22) and one inverter (23); As shown in FIG. 4A and FIG. 4B, a signal SA and a signal S are connected to the respective output sides.
= is obtained, and furthermore, the secondary signal SA and the signal SA are respectively supplied to the first selection circuit (15).

In addition, the other output terminal (18) of the position detection head (9) is connected to the input side of the other offset-adjusted amplifier (24), and the output side of the other output terminal (18) of the position detection head (9) is connected to the input side of the other offset-adjusted amplifier (24). ), the output side of the other amplifier (24) is connected to the input side of the other amplitude adjustment circuit (25), and the sine wave signal S[1 is obtained by amplifying the sine wave signal SFI obtained at A sine wave signal SR whose amplitude is adjusted to the same value as SA is obtained. In addition, the output side of the other amplitude adjustment circuit (25) is connected to the respective input sides of the other non-inverter (26) and the other inverter (27), such that the other non-inverter (26) and the other As shown in FIGS. 4A and 4B, signals S8 and S= are applied to the respective output sides of the inverter (27).
Further, the secondary signal Ss and the signal S= are respectively supplied to the first selection circuit (15).

Further, a first constant voltage power supply (28) capable of outputting a DC voltage V of a predetermined high level value and a second constant voltage power supply (29) capable of outputting a DC voltage V of a predetermined low level value are provided. A first selection circuit (1
5).

In addition, the output side of the other non-inverter (26) is connected to the first comparator 0.
0) to the non-inverting input terminal ■, and supplying the signal SB to the non-inverting input terminal ■, and connecting the variable resistor (
30), the average voltage vB of the signal SB is supplied, and a digital signal SC as shown in FIG. 4C is obtained using this average voltage vB as a reference.

In addition, the output side of one non-inverter (22) is connected to the second comparator (
11), so as to supply the signal SA to the non-inverting input terminal ■, and supply the average voltage vA of the signal SA to the inverting input terminal θ via the variable resistor (31), Using this average voltage vA as a reference, a digital signal SD as shown in the fourth diagram is obtained.

Further, the output signal Sc of the first comparator 00) is supplied to the first selection circuit (15), and the output signal Sc of the first comparator 00) is supplied to the first selection circuit (15).
) is connected to the input side of the clock generator (32) so as to obtain the clock pulses and the up/down signals of the Sc signal at the output side, and the clock pulses and up/down signals are connected to the input side of the clock generator (32). ), and one of the counters (12) performs counting according to the function table shown in FIG. In the function table shown in Fig. 5, “↑” and “↓” indicate the signal Sc.
"H" and "L" indicate the high level state, so-called "1", and the low level state, so-called "0" of the signal SD.

The diagram shown in FIG. 4 shows this count state, and in this case, the count values are 0, 1. 2
．． . . . represents a predetermined interval on Magneso l-(11. Therefore, hereinafter, this count value 0, 1
,2. The sections on magnet (1) corresponding to AO, At, A2 . It is expressed as...

Another comparison! The output signal SO of (11) is supplied to the first selection circuit (15), and the output side of the second comparator (11) is connected to the input side of the clock generator (32). and SD double signal amplifier down signal, and supply the same clock pulse and up/down signal to the other counter (13), and in this other counter (13), the function table shown in FIG. Make sure to count accordingly. This sixth
In the function table shown in the figure, "↑" and "↓" indicate the rising and falling states of the signal SO, and "H" and "L" indicate the high level state, so-called "1" and low level state of the signal SC. , so-called "0".

The diagram shown in FIG. 4F represents this count state, and in this case, the count values are 0.1, 2, .
. . . each represents a predetermined section on the magnet (1). Therefore, below, this count value Q, 1.2.
The section on magnet (1) corresponding to ... is BO,
Bl, B2. It is expressed as...

Also, one counter (12) and the other counter (13)
) are respectively connected to the input side of a second selection circuit (33), and in this second selection circuit (33), the output side of One counter (12) or the other counter (13)
Either one of the output sides of the counter (12) or (13) is selected to take out the output of one or the other counter (12) or (13).

Further, the output side of the second selection circuit (33) and the section designation signal input terminal (34) are connected to the input side of the third comparator (14), respectively, and the output side of the second selection circuit (33) is connected to the input side of the third comparator (14). The count value Y is determined by comparing the obtained count signal and the section designation signal.
When the period specified value X and the period specified value X match, a signal SG as shown in FIG. Supplying a signal SH as shown in H to the first selection circuit (15),
When the count Y is smaller than the section designation value X, a signal 31 as shown in FIG. 4 is supplied to the first selection circuit (15).
5).

Furthermore, in response to the input signals Sc, SD, SG, SH, SI and the section designation signal, the first selection circuit (15) outputs position signals SA, SW according to the function table shown in FIG.
, sB, S100, high level DC voltage VH or low level DC voltage vL is selected and output. In addition, in the function table shown in FIG. 7, "1" is the counter (12).
(13) represents the usage status of the counter (12).
) represents the unused state of (13). Further, "H" represents a high level state of the signal, and "L" represents a low level state of the signal.

Further, the output side of the first selection circuit (15) is connected to the fourth comparator (
35) is connected to the inverting input terminal e of the fourth comparator (35), and the variable DC voltage power supply (36) is connected to the non-inverting input terminal and a servo motor (37) capable of moving in directions b. In this case, the positive voltage is applied to the servo motor (
37), the servo motor (37) moves the position detection head (9) in the direction of the arrow a, and when a negative voltage is supplied, the servo motor (37) moves the position detection head (9) in the direction of the arrow.・Next, we will explain the operation of the position detection device configured in this way. In this example, first, the A4 section is designated as the specified section, and the power source (36) for specifying the position within the section is
The case where the voltage is set to <VM and point M is designated as shown in FIG. 4J will be explained.

When point M within the A4 section is specified in this way, the second selection circuit (33) selects the output signal SE of one counter (12).
is selected and this signal SR is supplied to the third comparator (14).

In this case, if the position detection head (9) is located within the AI section, since X>Y, the third comparator (14) sends the signal Sl to the first selection circuit (15). The first selection circuit (15) receives this signal S! In response to this, the second constant voltage power supply (29) is selected based on the function table shown in FIG. (35) is supplied to the inverting input terminal θ.

In this case, since the DC voltage vM (VM > VL) is supplied to the non-inverting input terminal ■ of the fourth comparator (35), the voltage difference (VM VL) (>O) is sent to the servo motor as an error signal. (37), and this servo motor (37) rotates to move the position detection head (9) in the direction of arrow a.

When the position detection head (9) enters the A4 section,
= Y, so the third comparator (14) converts the signal SG into the first
and the first selection circuit (15).
In response to this signal SG, selects the signal SW according to the function table in FIG. 7, outputs the voltage as shown in FIG. 4 J according to its position within the A4 section, and compares the output voltage with the fourth The signal is supplied to the inverting input terminal θ of the device (35).

Therefore, until the position detection head (9) reaches the M point, the first
Since the voltage output from the selection circuit (15) is smaller than vM, the error signal always takes a positive voltage value and the servo motor (37) continues to rotate.

When the position detection head (9) reaches the M point, the fourth
The voltage supplied to the inverting input terminal θ of the comparator (35) matches the voltage supplied to the non-inverting input terminal ■, and the error voltage becomes 0 [V], so the servo motor (37) stops rotating. Stop and proceed to position detection - The throat (9) stops corresponding to point M.

Next, the 84th section is designated as the specified section, and the voltage of the power supply (36) for specifying the position within the section is set as shown in Fig. 4k.
Let's explain the case where N points are specified.

When N points within the 84 section are specified in this way, the second selection circuit (33) selects the output signal SF of the other counter (13).
is selected and this signal SF is supplied to the third comparator (14).

In this case, since X<Y, assuming that the position detection head (9) is located within the 88 section, the third comparator (14) supplies the signal SR to the first selection circuit (15). The first selection circuit (15) responds to this signal SH and selects the seventh selection circuit (15).
The first constant voltage power supply (28) is selected based on the function table in the figure, and the high level DC voltage VH output from the first constant voltage power supply (28) is inverted by the fourth comparator (35). The signal is supplied to the input terminal e.

In this case, since the DC voltage VN (VN < VH) is supplied to the non-inverting input terminal ■ of the fourth comparator (35), the voltage difference (VN-VH) (<0) is sent to the servo as an error signal. The servo motor (37) rotates to move the position detection head (9) in the direction indicated by the arrow.

When the position detection head (9) enters the 84 section,
= Y, the third comparator (14) supplies the signal SG to the first selection circuit (15), and
) selects the signal SR according to the function table shown in FIG. 7 in response to the signal SC, outputs the voltage as shown in FIG. The signal is supplied to the inverting input terminal e of the comparator (35).

Therefore, until the position detection head (9) reaches the N point, the
Since the voltage output from the selection circuit (15) is greater than vN, the error signal takes a highly negative voltage value and the servo motor (37) continues to rotate.

When the position detection head (9) reaches the N point, the voltage supplied to the inverting input terminal θ of the fourth comparator (35) matches the voltage supplied to the non-inverting input terminal ■, and an error occurs. Since the voltage becomes O [■], the servo motor (37) stops rotating, and the throat (9) for position detection stops corresponding to the N point.

As described above, according to this embodiment, four magnetoresistive elements (51
(6) (7+ (81 constitutes a position detection head (9), and a two-phase position signal SA from this position detection head (9)
, SR, and further converts these position signals SA and SB into digital signals sc and SD to generate a signal S indicating the section in which the position detection head (9) is positioned with respect to the magnet (11).
R and SF are obtained, and the signals SE and SF are compared with the section designation signal, and the position detection head (9
) is located and the designated area of the position detection head (9) with respect to the magnet (1), the position detection head (9) is moved by the servo motor (37), and the position detection head (9) is moved with respect to the magnet (1). To detection - Position detection head (9) relative to the section where the throat (9) is located and magnet +1)
), the first selection circuit (1
5) selects a predetermined position signal, compares the voltage indicated by this position signal with the position specified voltage, and controls the servo motor (37) so that the voltage indicated by the position signal and the position specified voltage match.
The gutter (9) is moved to a specified position for position detection.

In addition, in this example, the output signal S of the position detection head (9)
Since the signals s;i; and s, which are inverted A and SR, are also used as position signals, the magnet
1) All positions above can be specified.

Therefore, according to this embodiment, it is possible to detect minute displacements that are less than the magnetization pitch of the magnet (1), thereby preventing the occurrence of a so-called dead zone, and enabling high-resolution position detection that is greater than the resolution determined by the magnetization pitch. There is an advantage in being able to do so. Incidentally, in this example, even if the gap between the magnet (1) and the position detection head (9) is 0.1~Q, and about 4mm,
Position detection with a high resolution of about 0 μm can be achieved. Moreover, in this example, the position signal output by the position detection head (9) is used as it is, and the position is detected using the analog value of this position signal, so high-resolution position detection is possible with a simple structure. There is an advantage in being able to

In addition, in the above-mentioned embodiment, the magnetoresistive element (5) (61
(7) Although the case where (8) is used has been described, it is also possible to use other magnetoelectric conversion elements such as a Hall element instead, and it is easy to obtain the same effects as described above in this case as well. I can understand it.

In addition, in the above embodiment, four magnetoresistive elements f5)
f61 (7) (Using 81, two-phase position signals SA, S
We have described the case where we obtain 6 days, but instead of this, we can obtain 6 days.
(If you use a magnetoresistive element of 3 or more phases to obtain a position signal of 3 or more phases, you will be able to use a more linear part of the position signal, so you can further increase the resolution. There is a benefit.

Furthermore, in the above embodiment, the magnet (1) is fixed and the position detection head (9) is moved, but instead of this, the position detection head (9) is fixed and the magnet (11 is moved). It is easy to understand that the same effects as described above can be obtained in this case as well.

Furthermore, the present invention is not limited to the above-described embodiments, and it goes without saying that various other configurations may be adopted without departing from the gist of the present invention.

〔Effect of the invention〕

According to the present invention, since it is possible to detect minute displacements that are less than the magnetization pitch, there is an advantage that position detection can be performed with a higher resolution than that determined by the magnetization pitch.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the position detection device of the present invention;
FIG. 2 is a diagram for explaining the position detection head used in one embodiment of the present invention, FIG. 3 is a diagram showing an equivalent circuit of the position detection head shown in FIG. 2A, and FIG. 5 is a diagram showing the function table of one counter; FIG. 6 is a diagram showing the function table of the other counter;
The figure is a diagram showing a function table of the first selection circuit, and FIG. 8 is a diagram for explaining a conventional position detection device. (11 is a magnet, (51 (61 (71 and (8) are each magnetoresistive element, (9) is a position detection head, 001
(11) (14) and (35) are comparators, (1
2) and (13) are counters, (15) and (33) respectively.
) are respective selection circuits, (28) and (29) are DC constant voltage power supplies, (32) are clock generators, (34) are section designation signal input terminals, (36) are variable power supplies for specifying position within the section, (37) ) is a servo motor. ≦Iff Conventional - Figure 8 of the 5 circles used to explain J - P, - 1 - PI - + - ~ - Six changes Figure 2 A standing book Shide, D's 〒no convex circuit Figure 3 tLIAE of the present invention A both T co, Diagram 4 Figure n Count (12) 1 millimeter A Cef y counter ( 13) /l J Hanoncho Fig. 5 Fig. 6 Roof 1 of J Shaku 1 & (+5) Stir 1 Section Fig. 7

Claims (1)

[Claims] It has a magnet magnetized at a constant pitch, and a plurality of magnetoelectric conversion elements arranged at a predetermined pitch with respect to the pitch of the magnet, so that it moves relative to the magnet, and 2 corresponding to the position
Equipped with a position detection head that outputs a position signal higher than the phase,
The above position signals are counted to obtain a count signal specifying a predetermined section on the magnet, and a desired phase position signal is selected from the above two or more phase position signals, and the above count signal and the above desired phase position signal are combined. A position detection device characterized in that the position of the position detection head with respect to the magnet is detected using an analog value.