JP4682598B2 - Encoder and encoder system - Google Patents

Description

  The present invention relates to an encoder and an encoder system.

An encoder and an encoder system include, for example, a magnet plate fixed to a rotating shaft, a magnetometer that detects magnetic flux from the magnet plate, and a count processing unit that detects rotational speed information indicating the rotational speed of the rotating shaft based on a change in magnetic flux The absolute code disk fixed to the rotation shaft, the light source for irradiating the absolute code disk with the irradiation light, and the rotation amount information indicating the rotation amount of the rotation shaft are detected based on the irradiation light passing through the absolute code disk. It is comprised from the code generator etc. (for example, patent document 1). Information indicating the detected number of rotations and amount of rotation is transmitted from each detector to the host system via a transmission line or the like.
JP-A-62-263600

However, in the encoder and encoder system described above, for example, when a failure occurs in the transmission line, or when a failure occurs in the power supply path for supplying power to the counting processing unit and the code generator, the rotation speed and There is a problem that information indicating the amount of rotation is not transmitted to the host system.
An object of the present invention is to provide an encoder and an encoder system that can reliably transmit information indicating the amount of rotation or the number of rotations to an upper system even when a failure occurs in a part of the encoder and the encoder system. .

In the encoder of the present invention, the first detection unit detects a rotation amount of the rotating body based on the first pattern provided on the rotating body, and the second pattern provided on the rotating body. And a rotation number detection unit for detecting the rotation number of the rotating body. Second detection unit has only the rotation speed detector which detects the rotational speed of the rotating body based on the second pattern. Further, the rotation amount detection unit optically detects the rotation amount based on the first pattern, and the rotation number detection unit electromagnetically detects the rotation number based on the second pattern.

Further , the first detection unit and the second detection unit may have power supply terminals to which power supplies independent from each other are supplied .

Further, a first output section, a second output for outputting information indicating a rotational speed that will be detected by the second detection unit that outputs a rotation amount and information indicating the rotational speed detected by the first detection section Part.
In the encoder system of the present invention, the encoder of the present invention, the first communication line connected to the first output unit, the second communication line connected to the second output unit, the first and second via the communication line, when the information indicating the rotational speed that will be transmitted from the first and second output portions are different from each other, and a error detection unit for outputting error information.

  According to the present invention, since there are two detection units, even if a failure occurs in one of the detection units, the information indicating the rotation amount or the rotation number is reliably transmitted to the host system, and the reliability of the encoder and the encoder system is improved. It can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a first embodiment of the encoder and encoder system of the present invention. The encoder system includes an encoder 100, a rotary shaft 102 (rotary body) connected to an output shaft of a motor or the like via a speed reducer, an LED 104, power supplies 108 and 110 independent of each other, and a communication path 112 (first first Communication line), communication path 114 (second communication line), and host system SYS.

The encoder 100 includes a rotating disk 122, a permanent magnet 124, a detection unit DET1 (first detection unit and output unit), and a detection unit DET2 (second detection unit and output unit). The detection unit DET1 includes photodiodes 12 and 14, an amplifier 16, an A / D converter 18, MR elements 22 and 24, comparators 30 and 32, a logic circuit 38, and a power supply terminal 42.
The detection unit DET2 includes MR elements 26 and 28, comparators 34 and 36, a logic circuit 40, and a power supply terminal 44. The rotating disk 122 and the permanent magnet 124 are detachably attached to the rotating shaft 102. An M series pattern and an incremental pattern (not shown) are formed in an annular shape on the outer peripheral portion of the rotating disk 122. The M series pattern and the incremental pattern will be described with reference to FIG.

The LED 104 is fixed at a position facing the rotating disk 122. The LED 104 irradiates the irradiation light toward the M-sequence pattern and the incremental pattern in order to detect information indicating the absolute position within one rotation of the rotary disk 122 and information indicating the displacement (rotation amount) from the absolute position.
The photodiodes 12 and 14 are arranged at positions facing the LEDs 104 through the first pattern of the rotating disk 122, respectively. The photodiode 12 receives light emitted from the LED 104 and transmitted through the opening of the incremental pattern formed on the rotating disk 122 as information indicating displacement from the absolute position of the rotating disk 122 every N pitches (for example, 9 pitches). And photoelectric conversion.

The photodiode 14 receives light emitted from the LED 104 and transmitted through the opening of the M series pattern formed on the rotating disk 122 as information indicating the absolute position of the rotating disk 122 in units of N pitches (for example, 9 pitches). Perform photoelectric conversion.
Amplifier 16 amplifies the analog signal by the photodiode 12, 1 4 is photoelectrically converted, and outputs the amplified analog signal to the A / D converter 18. The A / D converter 18 converts the analog signal amplified by the amplifier 16 into a digital signal.

The MR elements 22, 24, 26, and 28 are each composed of a magnetoresistive effect element and are disposed at positions facing the permanent magnet 124. The MR elements 22, 24, 26, and 28 are arranged at 90 ° intervals about the rotation axis 102 in order to detect forward / reverse rotation of the rotary disk 122.
The MR elements 22, 24, 26, and 28 detect the number of rotations of the rotating disk 122 as information indicating a change in the magnetic field generated from the permanent magnet 124, and output the detected information as an electrical signal. The comparators 30, 32, 34, and 36 shape the waveform of the electrical signal detected by the MR elements 22, 24, 26, and 28 and convert it into a digital signal.

  The logic circuit 38 generates information indicating the absolute position, the displacement from the absolute position, and the rotational speed of the rotating disk 122 based on the digital signals output from the A / D converter 18 and the comparators 30 and 32, respectively. The logic circuit 38 transmits information indicating the absolute position, the displacement from the absolute position, and the rotational speed of the rotary disk 122 to the receiving unit 116 of the host system SYS via the communication path 112.

The logic circuit 40 receives the digital signals converted by the comparators 34 and 36, generates information indicating the number of rotations of the rotating disk 122 based on the digital signals output from the comparators 34 and 36, and passes through the communication path 114. Information indicating the rotational speed of the rotating disk 122 is transmitted to the receiving unit 118 of the host system SYS.
The error detection unit 120 compares the information indicating the number of rotations of the rotating disk 122 transmitted from the logic circuits 38 and 40 with each other, and outputs error information if each information is different. In the present invention, two independent communication paths 112 and 114 are provided. For this reason, even when a failure occurs in the communication path 112 or the communication path 114, information indicating the number of rotations of the rotating disk 122 can be acquired by one of the receiving units 116 and 118.

  Independent power supplies 108 and 110 are connected to the power supply terminal 42 of the detection unit DET1 and the power supply terminal 44 of the detection unit DET2, respectively. For this reason, even if one of the power supplies 108 and 110 is cut off, either the detection unit DET1 or the detection unit DET2 can operate. Specifically, even when a failure occurs in the power supply 108 or the power supply 110, power is supplied to either the detection unit DET1 or the detection unit DET2. For this reason, the host system SYS receives information indicating the absolute position of the rotating disk 122 from the detection unit DET1, information indicating the displacement from the absolute position and information indicating the rotation speed, or rotation of the rotating disk 122 from the detection unit DET2. Any of the information indicating the number can be acquired.

  FIG. 2 shows an M series pattern and an incremental pattern formed on the rotating disk 122. As shown in FIG. 2, the M series pattern and the incremental pattern are each formed in an annular shape on the rotating disk 122. The M-sequence pattern has absolute patterns (2 to the power of N) generated from combinations of consecutive N-bit (for example, 9 bits) codes. Each absolute pattern is information indicating the absolute position of the rotating disk 122. In one absolute pattern, openings or closing portions respectively corresponding to the first bit to the Nth bit are formed for each unit length (one pitch).

The photodiode 12 shown in FIG. 1 has a plurality of light receiving surfaces arranged to face the opening portion and the closing portion of the incremental pattern. The photodiode 12 receives light transmitted through the opening of the incremental pattern, and photoelectrically converts the received light into an analog signal indicating displacement from the absolute position of the rotating disk 122.
The photodiode 14 is disposed so as to face the opening portion and the closing portion of the M series pattern. The photodiode 14 has two-phase light receiving surfaces of 0 ° and 90 ° for each pitch. The photodiode 14 photoelectrically converts light obtained by the light transmitted through the opening of the M series pattern formed on the rotating disk 122 into an analog signal indicating the absolute position of the rotating disk 122. The photodiode 14 is connected to the amplifier 16 through a control circuit.

  The permanent magnet 124 fixed to the rotating disk 122 shown in FIG. 1 is composed of a two-layer magnetic body having an N pole and an S pole. The normal rotation of the rotating disk 122 is detected by the MR elements 22 and 26. The reverse rotation of the rotating disk 122 is detected by the MR elements 24 and 28. The MR elements 22, 24, 26 and 28 each have two MR elements connected in series. When the rotating disk 122 rotates forward, the magnetic field from the N pole to the S pole is received, and the resistance value of the MR element orthogonal to the direction of the magnetic field increases. In response to the increase in the resistance value of the MR element, the voltages of the MR elements 22 and 26 are decreased. When the rotating disk 122 rotates in the reverse direction, the resistance value of the MR element that is orthogonal to the direction of the magnetic field increases due to the magnetic field from the north pole to the south pole. In response to the increase in the resistance value of the MR element, the voltages of the MR elements 24 and 28 increase. In this way, the MR elements 22 to 28 output an electrical signal indicating a change in potential as information indicating the number of rotations of the rotating disk 122.

  The comparators 30 to 36 receive electrical signals indicating changes in the potentials of the MR elements 22 to 28, respectively. The comparators 30 to 36 generate a binary (“0” or “1”) signal as information indicating the rotational speed of the rotary disk 122 based on the electrical signals received from the MR elements 22 to 28, respectively. The comparators 30 and 32 and the comparators 34 and 36 output the generated binary signals to the logic circuits 38 and 40 as information indicating the number of rotations of the rotating disk 122, respectively. Information indicating the absolute position within one rotation of the rotary disk 122 is obtained from the M-sequence pattern during the scan operation mode after the encoder system is powered on.

  As described above, in the present embodiment, the information indicating the rotational speed of the rotating disk 122 is received by the host system SYS via the communication paths 112 and 114 independent of each other. For this reason, for example, even when a failure occurs in either the detection unit DET1 or the detection unit DET2, information indicating the number of rotations of the rotary disk 122 can be reliably transmitted to the host system SYS. Information indicating the rotational speed, which is important information for controlling the industrial robot or the like, is reliably transmitted to the host system, so that it can be optimally controlled without causing the industrial robot or the like to malfunction. In an encoder having only one detection unit, even when a failure occurs in the detection unit, the control unit that controls the motor may not recognize the failure and stop the motor. On the other hand, in the present embodiment, when a failure occurs in either the detection unit DET1 or the detection unit DET2, the error detection unit 120 outputs an error signal, and the motor is controlled based on the error signal. The control unit can immediately stop the motor.

  When detecting the number of rotations by the optical device by detecting information indicating the number of rotations of the rotating disk 122 using the detection unit DET2 including only the magnetic devices such as the MR elements 26 and 28 and the comparators 34 and 36. In comparison, the power consumption of the encoder 100 and the encoder system can be reduced. In general, magnetic devices such as the MR elements 26 and 28 and the comparators 34 and 36 can be configured at a lower cost than optical detection devices. Therefore, the manufacturing cost of the encoder 100 and the encoder system can be reduced.

  The detection unit DET1 and the detection unit DET2 have power supply terminals 42 and 44, respectively, and are supplied with power from different power supplies 108 and 110, respectively. For this reason, even when one of the power supplies 108 and 110 is shut off, either the detection unit DET1 or the detection unit DET2 can be operated continuously. As a result, the host system SYS receives information indicating the absolute position of the rotating disk 122 from the DET1, information indicating the displacement from the absolute position and information indicating the rotation speed, or information indicating the rotation speed of the rotating disk 122 from the DET2. Either of can be acquired.

  FIG. 3 shows a second embodiment of the encoder and encoder system of the present invention. The encoder system includes an encoder 200, a rotating shaft 102, LEDs 104 and 104, power supplies 108 and 110, communication paths 112 and 114, and a host system SYS. In this embodiment, the detection unit DET1 has the same configuration as that of the first embodiment. Unlike the first embodiment, the detection unit DET2 includes an optical detection unit that detects an M-sequence pattern and an incremental pattern. That is, the detection unit DET2 includes photodiodes 12 and 14, an amplifier 16, an A / D converter 18, a logic circuit 46, and a power supply terminal 44. The host system SYS is different from the first embodiment in the receiving unit 126 and the error detecting unit 128. The receiving unit 126 of the host system SYS is connected to the logic circuit 46 via the communication path 114. The error detection unit 128 of the host system SYS is connected to the reception units 116 and 126. Other configurations of the encoder system are the same as those in the first embodiment. The same elements as those described in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

The logic circuit 46 generates information indicating the absolute position and the displacement from the absolute position of the rotary disk 122 based on the digital signal output from the A / D converter 18. The logic circuit 46 transmits information indicating the absolute position of the rotating disk 122 and the displacement from the absolute position to the receiving unit 126 of the host system SYS via the communication path 114.
The error detection unit 128 compares the absolute position of the rotating disk 122 transmitted from the receiving units 116 and 126 and information indicating the displacement from the absolute position, and outputs error information if the information is different.

In the present invention, as in the first embodiment, two independent communication paths 112 and 114 are provided. For this reason, even when a failure occurs in the communication path 112 or the communication path 114, information indicating the absolute position of the rotating disk 122 and the displacement from the absolute position can be acquired by either the receiving unit 116 or 126.
As in the first embodiment, the power supply terminal 42 of the detection unit DET1 and the power supply terminal 44 of the detection unit DET2 are connected to power supplies 108 and 110 that are independent from each other. For this reason, even if one of the power supplies 108 and 110 is shut off, the host system SYS receives information indicating the absolute position of the rotating disk 122 from the detection unit DET1, information indicating the displacement from the absolute position, and information indicating the number of rotations. Alternatively, either the information indicating the absolute position of the rotating disk 122 from the detection unit DET2 or the information indicating the displacement from the absolute position can be acquired.

As described above, also in this embodiment, the same effect as that of the first embodiment described above can be obtained.
FIG. 4 shows a third embodiment of the encoder and encoder system of the present invention. The encoder system includes an encoder 300, a rotary shaft 102, LEDs 104 and 104, power supplies 108 and 110, communication paths 112 and 114, and a host system SYS. In this embodiment, the detection unit DET1 has the same configuration as that of the first embodiment. Unlike the first embodiment, the detection unit DET2 (second detection unit and output unit) has the same configuration as the detection unit DET1. That is, the detection unit DET2 includes photodiodes 12 and 14, an amplifier 16, an A / D converter 18, MR elements 22 and 24, comparators 30 and 32, a logic circuit 38, and a power supply terminal 42. The host system SYS has a receiving unit 116 and an error detecting unit 132 corresponding to the detecting units DET1 and DET2, respectively. The error detection unit 132 of the host system SYS is connected to the two reception units 116. Other configurations are the same as those of the first embodiment. Detailed description of the same elements as those described in the first embodiment is omitted. The error detection unit 132 compares the information indicating the absolute position, the displacement from the absolute position, and the rotational speed of the rotating disk 122 transmitted from the two receiving units 116 with each other, and outputs error information if each information is different. .

In the present invention, as in the first embodiment, two independent communication paths 112 and 114 are provided. For this reason, even when a failure occurs in the communication path 112 or the communication path 114, information indicating the absolute position, the displacement from the absolute position, and the rotation speed of the rotating disk 122 can be acquired by one of the two receiving units 116. .
As in the first embodiment, the power supply terminals 42 of the detection unit DET1 and the power supply terminal 42 of the detection unit DET2 are connected to the power supplies 108 and 110, respectively. For this reason, even if one of the power supplies 108 and 110 is shut off, the host system SYS receives information indicating the absolute position of the rotating disk 122 from the detection unit DET1, information indicating the displacement from the absolute position, and information indicating the number of rotations. Alternatively, any one of information indicating the absolute position of the rotating disk 122 from the detection unit DET2, information indicating the displacement from the absolute position, and information indicating the number of rotations can be acquired.

As described above, also in this embodiment, the same effect as that of the first embodiment described above can be obtained.
In the first, second, and third embodiments, the example in which the light transmitted through the openings of the respective patterns formed in the rotating disk 122 is received every nine pitches has been described. The present invention is not limited to such an embodiment. For example, light may be received every 10 pitches. In this case, each position information of the rotating disk 122 is divided with higher density. As a result, the absolute position of the rotating disk 122 can be accurately acquired.

  In the above-described first embodiment, the example in which the logic circuit 38 transmits each piece of information on the rotating disk 122 to the receiving unit 116 has been described. The present invention is not limited to such an embodiment. For example, the logic circuit 38 compares the information indicating the displacement from the absolute position and the information indicating the rotation speed received from the A / D conversion unit 18 and the comparators 30 and 32, respectively. Error information may be output to As a result, the error detection unit 120 can detect abnormality of the encoder 100 and the encoder system by the reception unit 116 before receiving each information. Therefore, the abnormality of the encoder 100 and the encoder system can be detected at an early stage.

  Similarly, in the second embodiment, the logic circuit 86 compares the information indicating the displacement from the absolute position and the information indicating the rotational speed received from the A / D converter 18 and the comparators 30 and 32, respectively, If the information is different, error information may be output to the receiving unit 116. In the third embodiment described above, each logic circuit 38 compares the information indicating the displacement from the absolute position and the information indicating the rotation speed received from each A / D converter 18 and each comparator 30 and 32, respectively. If each information is different, error information may be output to each receiving unit 116.

  As mentioned above, although this invention was demonstrated in detail, said embodiment and its modification are only examples of this invention, and this invention is not limited to this. Obviously, modifications can be made without departing from the scope of the present invention.

1 is a block diagram showing a first embodiment of an encoder and an encoder system of the present invention. It is explanatory drawing of an M series pattern and an incremental pattern. It is a block diagram which shows 2nd Embodiment of the encoder and encoder system of this invention. It is a block diagram which shows 3rd Embodiment of the encoder and encoder system of this invention.

Explanation of symbols

12, 14 Photodiode 16 Amplifier 18 A / D converter 22, 24, 26, 28 MR element 30, 32, 34, 36 Comparator 38, 40, 46 Logic circuit 42, 44 Power supply terminal 100 Encoder 102 Rotating shaft 104 LED
108, 110 Power supply 112, 114 Communication path 116, 118, 126 Receiver 120, 128, 132 Error detector 122 Rotating disk 124 Permanent magnet 200 Encoder 300 Encoder

Claims (4)

A rotation amount detection unit that detects a rotation amount of the rotating body based on a first pattern provided on the rotating body, and detects a rotation number of the rotating body based on a second pattern provided on the rotating body. A first detection unit having a rotation number detection unit to perform,
And a second detector having only the rotation speed detector which detects the rotational speed of the rotating body based on the second pattern,
The rotation amount detection unit optically detects the rotation amount based on the first pattern,
The encoder that detects the number of revolutions electromagnetically based on the second pattern. The encoder according to claim 1, wherein
The encoder according to claim 1, wherein the first detection unit and the second detection unit have power supply terminals to which power supplies independent from each other are supplied . The claim 1 or in the encoder according to claim 2,
A first output unit that outputs information indicating the rotation amount and the rotation speed detected by the first detection unit ;
An encoder comprising: a second output unit that outputs information indicating the number of rotations detected by the second detection unit . An encoder according to claim 3 ;
A first communication line that will be connected to the first output unit,
A second communication line that will be connected to the second output section,
An error detection unit that outputs error information when the information indicating the rotation speed transmitted from the first and second output units is different from each other via the first and second communication lines. Characteristic encoder system .

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