JPS63242028A - Multi-rotation absolute address type position detector - Google Patents

Abstract

PURPOSE:To facilitate the change and increase in the total count by providing a rotary angle detection circuit detecting a rotary angle of a rotary shaft from an output signal of a read element and the number of revolution count circuit discriminating the direction of rotation of the rotary shaft from an output signal of the read element and counting number of revolutions based on its direction or rotation. CONSTITUTION:A signal corresponding to a code representing the absolute address of a rotary angle of a code disk 2 is outputted from a photodetector 7 and inputted to a position detection circuit 8 of the absolute address. The position detection circuit 8 detects the absolute address within one rotation of the code disk 2 from the output signal from the photodetector 7 and its detection signal is outputted. Outputs of a photodetector 7b reading the code of the most significant bit and a photodetector 7c reading the least significant bit (MSB-1) lower than the most significant bit by one in the photodetector 7 are inputted to a rotating direction discrimination circuit 9. The rotating direction discrimination circuit 9 supplies a signal incrementing the count by 1 in case of the right rotating direction and decrementing the count by one in case of the left rotating direction, for example, depending on the direction of rotation at every passing of the origin of the code disk 2 to a counter arithmetic circuit 10. The discrimination of the direction of rotation is performed by utilizing the code structure of the disk 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multi-rotation absolute address type position detector used as a sensor for positioning control of machine tools, industrial robots, etc.

[Prior Art] A detector shown in FIG. 3 is known as a detector for detecting the absolute position of multiple rotations. This type of detector is used for controlling electric VJ machines and the like, and is an important component of a closed-loop servo system as a position feedback sensor. As shown in the figure, the detector consists of a code plate attached to an input shaft a and a code plate d coupled through a reduction gear C so that the code plate rotates by one address every time the code plate rotates once. have. The code plates S and d are disks such as transparent glass plates with light-shielding codes indicating absolute address positions attached thereto.

A light emitting element (light emitting diode) e and a light receiving element (photodiode) f are mounted on the code plate d, respectively.
The light-dark pattern of the light transmitted from the light-emitting element e through the code plates and d is read by the light-receiving element.
Information on the position of the absolute address within one rotation of the input shaft a is obtained from the light receiving element f of the code plate d, and information on the rotational speed of the input shaft a is obtained from the light receiving element f of the code plate d. Note that g is a fixed slit to improve detection accuracy.

[Problems to be Solved by the Invention] However, the above-mentioned position detector requires a reduction gear C and two code plates d, and the mechanism and circuit groove bottom are complicated and expensive. Become.

Further, since there is a deviation between the signals of the code plate d and the code plate d due to the backlash of the reduction gear C, an optical element and a circuit for V scanning are required to synchronize them. Furthermore, in order to change the total count (maximum rotational speed), the gear ratio of the reduction gear C must be changed. Also,
When manufacturing a device with an extremely large total count (for example, 1000 revolutions), it is necessary to use a multi-stage reduction gear or add an additional code plate, which makes manufacturing expensive and difficult.

The present invention solves the above-mentioned problems of the prior art, and provides a multi-rotation absolute address type position detector which has a simple structure, can be manufactured at low cost, and can easily change and increase the total number of counts.

[Means for Solving the Problems] The present invention includes a code plate attached to a rotating shaft whose rotational position is to be detected and in which codes representing absolute rotational positions are arranged, and a code plate that reads the code on the code plate and corresponds to the code. a rotation angle detection circuit that detects the rotation angle of the rotating shaft from the output signal of the reading element, and a rotation angle detection circuit that determines the rotation direction of the rotating shaft from the output signal of the reading element and rotates based on the rotation direction. This is a multi-rotation absolute address type position detector equipped with a rotation number counting circuit that counts the number of rotations.

[Function] The rotation angle detection circuit corresponds to the code representing the absolute rotation position from the reading element (obtains information on the absolute rotation position within one rotation of the rotation shaft from the fi number. , determines the rotational direction of the rotating shaft from the output signal from the reading element, counts up the count value when it rotates once in the forward direction, and counts down when it rotates once in the reverse direction to count the number of rotations.

[Example] Embodiments of the present invention will be described below based on the accompanying drawings.

In FIG. 1, reference numeral 1 denotes an input shaft that is attached to a rotating shaft of a machine tool whose rotational position is to be detected and inputs the rotation to a detector. A disc-shaped code plate 2 is attached to the input shaft 1 in a coaxial arrangement. This embodiment is a photoelectric position detector like the conventional example shown in FIG. 3, and the code plate 2 has a transparent/non-transparent code pattern written thereon representing an absolute address.

Each concentrically arranged track 3 of the code plate 2 is assigned a bit code for each digit, the outermost track 3a is assigned the least significant bit, and the innermost track 3 is assigned the more significant bit. Track 3 on the innermost track is numbered sequentially.
The most significant bit (MSB) sign is attached to b.

On one side of the code plate 2, a large number of light emitting elements 4 such as light receiving diodes are arranged in the radial direction facing the code plate 2. Further, a slit plate 6 in which a slit 5 is formed for each track 3 of the code plate 2 is provided on the other side of the code plate 2 so as to face the light emitting element 4.
A light-receiving element 7 such as a photodiode is disposed behind the light-receiving element 7 .

The light emitted from the light emitting element 4 is transmitted to each track 3 of the code plate 2.
The light passes through the slit 5 of the slit plate 6 and is received by the light-receiving element 7 in a bright and dark pattern corresponding to the sign of transmission/non-transmission.

A signal corresponding to the code representing the absolute address of the rotation angle of the code plate 2 is outputted from the light receiving element 7, and is inputted to the absolute address position detection circuit 8. The position detection circuit 8 detects the absolute address within one revolution of the code plate 2 from the output signal from the light receiving element 7, and outputs the detection signal. Light receiving element 7
The outputs of the light receiving element 7b which reads the code of the most significant bit and the light receiving element 7c which reads the code of the bit (MSB-1) one lower than the most significant bit are also input to the rotation direction determination circuit 9. ing.

The rotation direction determination circuit 9 outputs a signal to a counting calculation circuit 10 for counting, depending on the rotation direction, each time the origin of the code plate 2 passes, for example, +1 for clockwise rotation and -1 for counterclockwise rotation.
send to The direction of rotation is determined using the constituent code (Ill) of the code plate 2.
! This can be done using binary or Gray codes).

For example, in the case of Gray code, the most significant bit (MSB)
Then, 0°~180° is the opaque part, 180''~360°
is a transmitting part, and the output signal from the light receiving element 7b is O (Low) from 00 to 180'' as shown in FIG.
O' to 360' becomes 1 (1-1i (Jh). Also, the bit before the most significant bit (MSB-1) is out of phase by 90 degrees from the most significant bit, and the light receiving element 7C
As shown in Figure 2, the output signal from
and 270°~360° is O (Low), 906~
270° becomes 1()-1ight). Therefore, when the origin (Oo) passes, MSB-1 is O and M
When SE3 switches from 1 to O, it counts up as a clockwise rotation, and when MSB switches from O to 1 with MSB-1 being 0, it counts down as a counterclockwise rotation, and the number of rotations of the code plate 2 is counted. can.

The counting calculation circuit 1o counts the number of rotations as described above based on the number from the rotational direction determination circuit 9, and outputs the number of rotations calculated by 8I via the output circuit 11. Therefore, for example, when this detector is connected to the shaft of a ball screw, the output of the output circuit 11 indicates the rotational speed of the shaft, and the output of the position detection circuit 8 indicates the angle of the shaft within one rotation, so both outputs indicate the rotation speed of the shaft. The current position of the nut on the shaft of the ball screw can be determined.

In addition to an external power source, this detector has a built-in battery 12 that maintains the rotation count function even when the external power source is cut off. When the external power source is cut off, the battery 12 operates the rotation direction determination circuit 9 and the counting calculation circuit 1o.
Current is supplied to the light emitting element 4a and the light receiving elements 7b and 7c necessary for reading the MSB and MSB-1 of the code plate 2, and only the rotation number counting function is activated. This switching is performed by the power source selection circuit 13. Note that the light emitting element 4
A and the light receiving elements 7b and 7c are supplied with current like other light emitting and light receiving elements even when external power is supplied.

In this way, the number of rotations of the input shaft 1 is counted even while the external power is turned off, so even if the input shaft 1 rotates during that time, the position detection circuit 8 and the output circuit 1 will be counted when the external power is turned on again.
An output of 1 indicates the correct current absolute position. That is, when viewed from the outside, this detector functions similarly to a conventional gear type detector.

If the battery 12 is a secondary battery and is charged when the external 'Ii source is energized, there is no need to replace the 7r1 battery for a long period of time. The operating time of the rotation speed counting section (counter section and reading section) when the external type FA is shut off is determined by the capacity of the built-in battery, but in order to save power and ensure long-term operation, it is recommended to use a C-MOS counter. It is also preferable to use a magnetic type instead of a rechargeable type, in which the code on the code plate is represented by a magnetized part and a non-magnetized part, and a magnetoresistive element is used as a reading element.

Further, in this embodiment, all counted quantities are determined by the setting device 14.

You can set it freely. Count operation circuit 1
The set value of the maximum rotational speed is inputted to 0 from the setting device 14. The counting calculation circuit 10 compares the accumulated rotational speed count value with the set value of the setter 14, and if a +1 signal is added when the count value is equal to the set value, the count value is set to zero, If a signal of -1 is added when the count value is zero, the count value is made the set value of the setter 14. Since the total count (maximum rotation speed) can be set and changed freely in this way, this detector is versatile.For example, this detector can be connected to a drive shaft to drive an indexing table via a reduction gear. It is effective when That is, if the indexing table rotates once when the drive shaft rotates n times, the total count of the detector may be n rotations. This is convenient because when the index table rotates once, the output of the rotational speed of the detector also goes around once and returns to the initial value.

[Effects of the Invention] According to the present invention as described above, the following excellent effects are exhibited.

(1) It does not require a reduction gear in conventional detectors, which simplifies the mechanism, reduces size, and reduces costs. (2) Only one code plate reduces the number of reading elements. , fil +9] circuit for correcting the deviation between the code plates, etc., the number of revolution counting circuits increases, but the cost of the entire circuit can be reduced.

(3) Since the number of revolutions is counted electrically, the total number of counted revolutions can be easily set and changed. Therefore, unlike conventional reduction gear type detectors, there is no need to manufacture multiple reduction gears with gear ratios depending on the type of total rotation speed (also, it is easy to create a detector with a total rotation speed of 3 or 4 digits). can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of a multi-rotation absolute address type position detector according to the present invention, FIG. 2 is a waveform diagram for explaining an example of rotation number counting in the same detector, and FIG. FIG. 2 is a perspective view showing the configuration of a code plate and a photodetector portion of a conventional multi-rotation absolute address type position detector. In the figure, 1 is an input shaft, 2 is a code plate, 3 is a track, 4 is a light emitting element, 5 is a slit, 6 is a slit plate, 7 is a light receiving element, 8 is a position detection circuit, 9 is a rotation direction determination circuit, 10 11 is a counting operation circuit, 11 is an output circuit, 12 is a battery, 13 is a power source selection circuit, and 14 is a setting device. Patent Applicant: Ishikawajima-Harima Heavy Industries Co., Ltd. Representative Patent Attorney: Nobuo Kinutani Figure 1

Claims (1)

[Claims] A code plate is attached to the rotating shaft whose rotational position is to be detected and is arranged with codes representing the absolute rotational position, a reading element reads the code on the code plate and outputs a signal corresponding to the code, and the output signal of the reading element is detected. It is characterized by comprising a rotation angle detection circuit that detects the rotation angle of the rotation shaft, and a rotation number counting circuit that determines the rotation direction of the rotation shaft from the output signal of the reading element and counts the number of rotations based on the rotation direction. A multi-rotation absolute address type position detector.