JPS60218027A - Encoder - Google Patents

Abstract

PURPOSE:To perform total position detection by providing a pulse generating circuit which has a period shorter than the time when two magnetic sensors cross a magnet and a signal processing circuit which receives a sensor signal and detects the rotation position, etc., of a rotary disk in response to the sensor signal. CONSTITUTION:An A-phase signal SA is inputted to the set input of a flip-flop FF1, which is set to generate an ON output SA1. The output SA1 is applied to a terminal A0 of a decoder DECDR and also inputted to the set input of a trailing FF2, and a following clock CLK1 shorter than the operation period of a magnetic sensor is applied to an FF2, which is set and generates an ON output SA2. The output SA2 is also applied to a terminal A1 of DECDR. The FF1 is reset with the next CLK1 after the signal SA is ceased and the FF2 is reset with the next CLK1. Signals SB1 and SB2 are obtained through FF3 and FF4 similarly as to a B-phase signal SB and applied to terminals A2 and A4 of DECDR. The decoder performs conversion to an up/down signal SUD the signals SA1 and SA2, and SB1 and SB2, but the output is counted up by an up/down counter 87 when the rotary disk rotates forward or counted down when reversing.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an encoder, and more specifically to a magnetic incremental encoder that uses a magnetic incremental encoder to determine the rotational direction, number of rotations, and rotational position of a rotating shaft connected to the encoder in an absolute format. This paper relates to an encoder that can be calculated using .

Prior art encoders are widely used for precise position detection of moving working machines such as NCs.

There are generally two types of encoders: incremental type and absolute type. The former is a rotating plate fixed to a rotating shaft for detecting the movement of a working machine, and magnets are provided at equal intervals along the circumference of the rotating plate, and magnetic sensors are also provided opposite the rotating plate. It is designed to detect the rotation of the magnet of the rotating plate that rotates with the rotation of the rotating plate.If the rotating plate is rotating in the forward direction, an incremental signal is output, and if it is rotating in the reverse direction, an incremental signal is output. It is designed to detect the position of the axis. On the other hand, in the latter case, multiple rows of magnetic channels each having a predetermined /4' turn are provided along the circumference in the radial direction of the rotary plate, and the magnetic nolin of the channels is detected by multiple magnetic sensors. This allows the position to be detected uniquely (absolutely). Incremental encoders have the advantage of having a simple rotary plate and a simple detection circuit, but the power for the detection circuit is usually supplied from the power supply on the work machine side, and when that power goes -H off, the power is restarted. There is a problem in that the position of the rotating shaft cannot be immediately determined when the device is turned on, and the signals (incremental/decremental) from the reference position must be counted again. On the other hand, in the absolute type encoder, even if the power is turned off by -H, the position of the rotary shaft can be immediately determined when the power is turned on again, but there is a problem in that the structure of the rotary plate and the detection circuit become complicated.

Furthermore, both the above-mentioned incremental encoder and absolute encoder are generally configured to detect only the rotational position of the rotating shaft within one rotation, and cannot detect the number of rotations of the rotating shaft itself in the encoder itself. Therefore, it is necessary to integrate the number of rotations and the rotational position of the rotary shaft using the rotational position signal within one rotation in an external circuit of the encoder, that is, to calculate the total moving distance of the working machine.

In order to solve the above-mentioned problems, the inventor of the present invention invented a "/4 Luz encoder for detecting the rotation of a rotating body" (Japanese Patent Application No. 59-017103 and Japanese Patent Application No. 59-017).
No. 104), and r-arm encoder (filed March 10, 1988). All of these applications are capable of detecting the number of rotations and the direction of rotation of a rotating body, but all of them use an absolute encoder and the rotary code plate is somewhat complicated. In addition, both applications for ``No. 4 pulse encoder for detecting the rotation of a rotating body'' require an additional sensor (i-element and a detection element to be provided on the fixed part) to the rotating code plate in order to detect the number of rotations and the direction of rotation of the rotating body. figure,
Furthermore, the latter "pulse encoder" also has an additional detection element, making the structure somewhat complicated.

Furthermore, although all of the above methods use a method of applying power in a sampling manner in order to reduce the power consumption of the circuit, it has been found that the reduction in power consumption is not necessarily sufficient.

OBJECTS OF THE INVENTION It is an object of the present invention to detect in absolute format the number of rotations and direction of rotation of a rotating shaft to be detected by an encoder, as well as the rotational position within one rotation, using a simple structure and a relatively simple circuit. Another object of the present invention is to provide an encoder with low power consumption.

Structure of the Invention In order to achieve the above object of the present invention, the encoder of the present invention was realized based on the technical ideas listed below. That is, the main body of the encoder is of an incremental type with a simple structure, and no additional transmitting elements or detecting elements are used. On the other hand, in order to detect the number of rotations and the direction of rotation, the operating conditions of the conventional incremental type detection element are changed to the signal processing technique according to the present invention, and the detection signals obtained thereby are processed. Further, in order to prevent the one-rotation position signal of the incremental encoder from being lost due to a power cut, a battery is used as the circuit power supply, which does not cause the power to be cut off due to external conditions. However, the circuit must be designed to minimize power consumption so that the battery life is sufficient for the encoder service period or maintenance period.

Therefore, in the present invention, as a basic form, the first and second
a rotating plate in which magnets with polarities of
and a second magnetic sensor, wherein the second magnetic sensor detects a rotational position that is 90 degrees behind the first magnetic sensor;
an oscillation circuit that generates a /4' pulse with a period shorter than the time it takes for one of the magnets to cross the second magnetic sensor; Signal processing is provided for detecting the rotational position of the rotary plate and at least one of rising and falling of the received signal to calculate the rotational direction and rotation speed of the rotary plate, the magnetic sensor and the signal processing circuit. An encoder is provided, characterized in that the encoder is activated in response to a pulse from the oscillation circuit.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a diagram showing a schematic cross section of an encoder 1 of the present invention. In FIG. 1, the encoder 1 has a rotating shaft 2 that rotates according to the movement of the working machine in order to detect the position of a working machine such as an NC, and a rotating plate 6 that is fixed to the rotating shaft and rotates with the rotation of the rotating shaft 2. , a circuit section 10 and a battery 1, which will be described later, are mounted on a substrate 7 provided on one side of the rotary plate.
1 is provided. On the other hand, the board 8 is placed across the rotary plate 7.
A base 3 having a hole through which the rotating shaft 2 passes is provided opposite to the base 3, and a magnetic sensor 4.5 is provided on the base.

As shown in the plan view of FIG. 2, the rotary plate 6 is provided with a plurality of magnets successively disposed along its circumference.

In this embodiment, 2,500 magnets are provided per circumference. Also, the positional relationship between the magnet, magnetic sensors 4 and 5, and O is the third.
As shown in the figure, the second magnetic sensor 5 is provided so as to be 90 degrees behind the first magnetic sensor 4 in the direction in which the rotary plate 6 rotates in the forward direction. Magnetic sensor 4, 5
The sensor uses a sensor whose resistance changes depending on the magnetic flux from the magnet, such as a thin film sensor made of Malloy. The magnetic sensor itself does not react to the NS polarity and cannot detect the direction, and it does not react if the center IC of the N8 pole is present. Therefore, as described above, the first magnetic sensor and the second magnetic sensor are placed 90 degrees out of phase, and when one end is at the center of the N8 pole, the other end is at the strongest position of the magnetic pole, so that the direction of rotation of the rotating plate can be detected. I have to.

FIG. 4 shows a circuit diagram of the electric circuit section 100 shown in FIG. 1. The electric circuit section 10 has a clock/9rus CLKo, (
The oscillation circuit 8.0 which generates FIG. 5(,)),
The resistance changes of the monostable multi-nobbler 81 and the magnetic sensor 4.5, which generate the circuit driving clock signal CLKI (FIG. 5(b)) in response to the falling edge of the signal CLKO. Amplifying circuits 82 and 83 each consisting of a transistor and a resistor for amplification, a rising edge detection circuit 84 for detecting the rising edge and falling edge of two signals from the amplifier circuit, and a rising edge detection circuit 84 for detecting the rising edge and falling edge of the two signals from the amplifier circuit; OR darts 85 and 86 that take an OR when outputting a falling edge detection signal, and the OR gate 85
or 86, is provided with an up/down (reversible) counter 87 for counting "increase by 1" or "decrease by 1" according to the output signal of 86.

The rise/fall detection circuit 84 is a flip-flop FF operated by the signal 5A (A phase signal) on the magnetic sensor 4 side.
I and FF2, a flip flow operated by signal 5B (B phase signal) on the magnetic sensor 5 side.

It consists of FF3 and FF4, and a 4-line in-decoder DECDR which accepts the signals of these seven flip-flops FFI to FF4, decodes them, and outputs a rising or falling signal. That is, the decoder DliICD
R is the output 8A1 of flip-flops FFI to FF4
, SA2, 881, and 812 as “1” and “
2”, “4”.

It accepts it as a signal of "8" and outputs it as a θ~15010 communication signal.

A battery 9 is connected to the above-mentioned circuit as a power source.

The battery 9 is also used to detect changes in resistance of the magnetic sensors 4 and 5.

Referring to the timing chart in Figure 5,
The operation of the encoder of the present invention shown in the figure will be explained.

The rotating speed of the rotating shaft 2 changes depending on the moving speed of the working machine whose position is to be measured, but here, the rotating speed is 1200 r at a maximum.
Assume that it rotates at pm. As mentioned above, since there are 2,500 magnets in one rotation of the rotary plate 6, when the rotary plate 6 rotates in the normal direction (for example, clockwise) at the maximum speed, the frequency is 50 kHz. Therefore, up to 50 kHz.

A magnetic sensor signal with one period τ=20μ (6) is obtained.

However, in the present invention, battery 9. ! D. From the viewpoint of minimizing power consumption and calculating the rotation direction and number of rotations of the rotating shaft, the circuit is operated for a short period of time.

The oscillation circuit 80 generates an excitation/f pulse CLKo that minimizes the detection time of the magnetic sensors 4 and 5 and the amplifier circuits 82 and 83. The period t of the /f pulse CLKo is (Fig. 5(b)
)) must be shorter than the period τ shown in FIG. 5(a). FIG. 5(a) K, which detects the passage of each of the magnets shown in the diagram, must be small (both t-τ), and is also used to detect rising and falling.

On the other hand, within the cycle, the on time t1 and the off time t
3, the on time t1 is the time that can be detected stably by the magnetic sensors 4 and 5, and the circuit 10 can operate stably, whichever is as short as possible from the viewpoint of minimizing power consumption. Good. In view of the above conditions, in this example, 5μ (6) + * 1-2μ
■3μ(6), that is, the frequency of the arm clock CLK, is 2
00 kHz. Therefore, the output clock signal CLK1 of the multivibrator 81 (Fig. 5 (C)
) is also 200 kHz.

When the rotary shaft 2 rotates at the maximum speed, the resistance change of the magnetic sensor 4 changes four times by one pitch with a time width corresponding to the ON time of RI Il + and RI CLKo, and this change causes the change in the resistance of the magnetic sensor 4 to change 4 times.
2 to obtain a physiognomic output of 8A (Fig. 5(d))
). The magnetic sensor 5 similarly changes four times, but the phase of this change is 90 degrees behind the change in the magnetic sensor 4, and is amplified by the amplifier circuit 83 to obtain a B-phase output 8B (see Fig. 5).
・)).

By applying the physiognomic signal SA to the set input of the 7 lip FFI, the 9 FFI is set and the output is 8 A.
1 is turned on (FIG. 5(f)). The output 8A1 is applied to the terminal AOaC of the decoder DECDH and is also applied to the set input of the next stage 7 lip-flop FF2. Output SA2 also turns on (
Figure 5(g)). The output SA2 is also decoder DECDR (
Applied to the DA1 terminal. 7s, deflop F
FI is reset at the next clock CLK1 after the signal 8A is cut off, and FF21C is reset at the next clock CLK1.

As for the B-phase signal 8B, flip-flop, de-F
Signals 881 and 812 shown in FIGS. 5(h) and (1) are obtained via F3 and FF4, and these signals are applied to the decoder DECDR+1) A 2 and A 3 terminals.

The above signal SAI applied to the decoder DECDRK,
8A2.

The decoder according to 881.882 converts it into an up-down signal SUD as shown in FIG. 5(j) and outputs it, but the output is changed as shown in FIG. It is connected to the Azzo down counter 107 so that it is incremented (added) and decremented (subtracted) when rotating in the opposite direction. In this embodiment in which the rotation is normal, from FIGS. 4 and 5 (J), 8.
In the case of D-1, a down signal is output, but in the case of 8go-L4, an AyfM signal is output, so the Azzo down counter 87 is incremented by 1 by one pitch. It can be seen that the magnet on the rotary plate 6 moves forward by one pitch in the forward direction of K. Same as below K
The M-order rotary plate 7 times the counter 87 is counted.

When the rotating shaft is reversed, the up/down counter 87 decrements every bit and every magnet.

It is assumed that stain pressure is constantly applied to the above circuit by the battery 9. Therefore, a situation where the position is unknown due to a power cut does not occur, and the rotational position of the rotary shaft is always maintained, and the rotational position signal processed for normal rotation or reverse rotation can be outputted as a so-called absolute signal from the down counter 87. Alternatively, in the up-down counter 87, the number of forward rotations/arm pulses is generated for every 49 russ of normal rotation to 2500 russ of forward rotation in accordance with the number of magnets on the rotary plate. In the case of a reverse rotation, the number of reverse rotations and ramifications are generated. This is K, so you can also see the number of rotations and the direction of rotation.

As the battery 9, a relatively long and stable battery such as a lithium battery is used, but in order to be able to constantly apply voltage to the circuit, it is necessary to use one magnetic sensor as described above. 4.5 and amplifier circuits 82 and 83 are applied with a pulse of minimum time width (Fig. 5(b), tt) necessary for their operation and position detection to minimize power consumption. , for example, CMOS devices, which consume less power, are used as circuit elements.

The above description of the operation has been made for the case where the rotary shaft 2 rotates at the maximum speed, but the rotary shaft changes depending on the moving speed of the working machine, and there are cases where the rotary shaft does not rotate.

For example, if the rotating shaft rotates at 60 rpm, the period τ' of one pitch will be twice that of the above example, that is, 40p(6) (FIG. 6(a)). On the other hand, if the oscillation circuit 80 remains at the same frequency B OkHz O as described above, a double O detection signal will be obtained within one pitch, but K for detecting rising or falling will have four values as above. That's enough. Therefore, as shown in FIG. 6, the output signal of the decoder DffiCDR, which also indicates the rotational speed of the rotary plate, is inputted via the OR (r-) 89, and the distance between the input and the mother pulse O is calculated by Luz C
A circuit 88 for counting LKl and calculating the oscillation period of the oscillation circuit according to the rotation speed of the rotating shaft is provided, and the oscillation circuit 80
/ is arranged so that the oscillation period can be changed according to a command from the circuit 88. In this example, the oscillation period t' is doubled (
Figure 7(b)). However, the time t1 for turning on the magnetic sensor, etc.
is the previous passage. By doing so, the number of times the magnetic head etc. are operated is reduced, so that the power consumption of the battery can be significantly reduced. By doing so, it is possible to extend the life of the battery to approximately the same extent as the service life of the encoder.

In the above example, a case has been described in which both the rising edge and the falling edge are detected, but it is also possible to detect only one of them. Further, the rising/falling multi-circuit 84 may be of any other type as long as it has the same functions as those described above. Further, the Azzo down counter does not need to be a single add-down counter, as long as it performs reversible counting similar to the above, and two inexpensive counters may be combined.

In the above description, the human face and B-phase signals have been described, but as in the conventional case, the inverted human face and the inverted B-phase can also be used together.

Effects of the Invention As described above, according to the present invention, it is possible to detect a substantially absolute rotational position signal, the number of rotations, and the rotational direction by using an incremental mechanism, thereby detecting the total position. An encoder capable of performing detection can be realized.

Further, according to the present invention, the power consumption of the encoder according to the present invention can be significantly reduced.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an encoder as an embodiment of the present invention, Fig. 2 is a front view of the rotary plate shown in Fig. 1, Fig. 3 is a diagram showing the positional relationship between the magnet and the magnetic sensor, and Fig. 4 is A circuit diagram showing one embodiment of the circuit in FIG. 1, FIGS. 5(,) to (j) are timing diagrams of the circuit in FIG. 4, and FIG. 6 is a diagram showing another embodiment of the circuit in FIG. 1. , FIGS. 7(a) and 7(b) are timing diagrams of the circuit shown in FIG. (Explanation of symbols) 1... Encoder, 2... Rotating axis, 3... Base,
4゜5... Magnetic sensor, 6... Rotating plate, 7... Board, 8... Electronic circuit, 9... Battery. Figure 1 Figure 2 Figure 7 (b) Ct to b'' Procedural amendment (spontaneous) October 1, 1980 Director General of the Patent Office Manabu Shiga 1, Indication of the case 1988 Patent Application No. 073871 2 , Name of invention encoder 3, Relationship with the person making the amendment Patent applicant name: FANUC CORPORATION 4, Agent address: 8-10 Toranomon-chome, Minato-ku, Tokyo 105 (4 others) /”'h@ L, 1”'j'\, 5,? ! Positive object (1) ``Detailed description of the invention'' column of the specification (2) ``Brief explanation of the drawings'' column of the specification' (3) Drawings (Figures 4, 6, and 8) ) 6. Contents of amendment (11 Detailed description of the invention column (a) Insert rD type 1 after "operates" on page 10, line 15 and line 17. (b) Page 11 Insert “(see Figure 5 (al)”) after “obtained” in line 18. In this embodiment, . Therefore, the up/down signal 5tLD all becomes the amplifier pulse signal SU.The decoder DIICDR is connected to the gates G1 to G as shown in FIG.
It consists of 14, SAI +SA2 +SB1
When +SR2 becomes 1, 7, or 8.14, up pulses are output from gates Gl, G7, G8, and G14, respectively. If the B-phase signal SR leads the A-phase signal S^ in phase, that is, if the encoder rotates in the opposite direction, then SAI +SA2 +SB1 +
When SR2 becomes 2,4°11,13, gate G2. G
4. Only down pulses are output from Gll and G13. These up or down pulse signals are counted by an up/down counter 87. 1(d) Page 14 No. 11
Line (7) Correct r107 J to '87J. (2) Brief description of the drawings section Page 18, line 11 of the specification, before "is."
Add. (3) (a) Figures 4 and 6 will be corrected as shown in the attached sheet. (b) Add attached Figure 8. 7. Attached document catalog correction drawings (Fig. 4, Fig. 6, and Fig. 8) 1 copy

Claims (1)

[Claims] 1. A rotating plate fixed to a rotating shaft and having a plurality of magnets of first and second polarity alternately provided along the circumference at predetermined intervals; first and second magnetic sensors disposed opposite the magnet and responsive to the magnetic flux of the magnet;
In the encoder, the magnetic sensor detects the rotational position with a predetermined phase difference from the first magnetic sensor.
an oscillation circuit that generates /4 ps with a period shorter than the time it takes for the rotary plate to cross; Signal processing is provided for detecting at least one of a rising edge and a falling edge to calculate the rotational direction and rotational speed of the rotary plate, and the magnetic sensor and the signal processing circuit are operated in response to pulses from the oscillation circuit. What I tried to do
-*Slightly, Ennida. 2. The encoder according to claim 1, wherein the period of the pulse generated in the oscillation circuit is changed in response to the rotational speed of the rotating plate. 3. The encoder according to claim 1 or 2, wherein the on-time of the master pulse generated in the oscillation circuit is a minimum of 6 constant times defined by the operating time of the magnetic sensor, etc. . 4. The signal processing circuit detects at least one of the rising edge and falling edge of the signal from the first and second magnetic sensors, and the rotating plate in response to the signal from the detection circuit. 4. The encoder according to claim 3, further comprising a counter having an up/down counting function to calculate the direction of rotation and number of rotations of the encoder. 5. The encoder according to claim 4, wherein the oscillation circuit and the signal processing circuit are made of CM)S devices. 6. The encoder according to claim 5, wherein the encoder's power source is a battery.