JPS61212726A - Absolute value type rotary encoder - Google Patents

Abstract

PURPOSE:To achieve a higher resolution, by providing a control means which turns a (n+1)th code plate by a specified angle each time an n-th code plate makes a turn to output a code pattern read out as coding signal according to the angle of rotation of an input shaft to enable the detection of the angle of rotation exceeding 360 deg.C. CONSTITUTION:When the rotation of a load is transmitted through an input shaft 1 and a first stage code plate C1 makes a turn positively, a pulse motor PM turns a second stage code plate C2 by minimum division angle positively. Thereafter, each time the code plate C1 makes a turn positively, the motor PM turns the code plate C2 by minimum division angle positively. The same action is done in the reverse way. Then, the code pattern corresponding to the angle of rotation from the reference positions of the code plates C1 and C2 are read out by detector sections S1 and S2 and outputted from a control circuit 3 as coding signal corresponding to the angle of rotation of the input shaft 1. In addition, the rotatable range of the input shaft 1 can be extended by increasing the number of stages thereby enabling a higher resolution.

Description

Detailed Description of the Invention [Field of Industrial Application] This invention relates to an absolute value type rotary encoder, and particularly relates to an absolute value type rotary encoder that can detect a rotation angle of 360 degrees or more without using a reduction mechanism. .

"Prior art" Generally, rotation angle detectors that detect rotation angles are:
Rotary encoders are widely used. There are two types of rotary encoders: incremental type and absolute value type. , the incremental type has a simple mechanical structure, and the human power axis is 36
Although it has the advantage of being able to detect the rotation angle even when it rotates more than 0 degrees, the rotation angle is detected by counting the number of pulses of the pulse signal output with the rotation of the human shaft with a counter. Because it is a thing,
Only the relative rotation angle from a certain arbitrary position can be obtained. Therefore, errors will occur if the counter malfunctions (miscounts) due to external noise, etc. Also, if the power is turned off for some reason, or if the power is turned off at the end of the work, the rotary encoder will automatically transfer the position information at that point. I can't keep it in place. On the other hand, the absolute value type can obtain encoded signals corresponding to each rotation angle, so it is possible to detect the absolute rotation angle with respect to the reference position, and therefore the position at the time the power is turned off. This is suitable when you want to keep information in the rotary encoder itself, or when you want to prevent detection errors from accumulating when they occur for some reason. However, due to its structure, the absolute value type cannot detect the rotation angle when the input shaft rotates 360 degrees or more.

"Problems to be Solved by the Invention" Conventionally, when attempting to detect a rotation angle of 360 degrees or more using an absolute value type rotary encoder, a first rotary encoder directly connected to an input shaft, A method has been adopted in which a second rotary encoder is provided downstream of this rotary encoder via a reduction gear. However, the method of transmitting the rotation of the input shaft to the second rotary encoder via the reduction gear has the following drawbacks.

(2) The range of rotation angles that can be detected and the resolution of the object to be measured are determined by the reduction ratio of the reduction gear, so once set, it is difficult to change them.

■Since the reduction gear is directly connected to the shaft to be measured,
Installation requires a relatively large space to be occupied, and therefore installation is space-constrained.

■Detection errors may occur due to pitch errors and backlash of the reduction gear.

This invention was made in view of the above-mentioned circumstances, and provides an absolute value type rotary encoder that can detect a rotation angle of 360 degrees or more without using a reduction mechanism, thereby improving resolution. The purpose is to

``Means for Solving the Problems'' This invention provides a first code that is rotatable independently of each other, and in which code patterns corresponding to rotation angles from each reference position are recorded in advance at each predetermined angle. - an Nth code plate, an input shaft connected to the first code plate, a drive means for rotationally displacing each of the second to Nth code plates by the predetermined angle in a stepwise manner; reading means provided corresponding to each of the first to Nth code plates and reading out the code pattern from each code plate; and the nth (n≧
1) The reading means corresponding to the code plate of 1) controls the drive means corresponding to the n±1th code plate based on the read code pattern, and every time the nth code plate rotates once, the driving means corresponding to the n+1th code plate is read out. The present invention is characterized by comprising a control means for rotationally displacing the code plate by the predetermined angle and outputting the code pattern read by each of the reading means as an encoded signal corresponding to the rotation angle of the input shaft.

"Operation" Each time the first code plate connected to the input shaft rotates once, the second code plate is rotationally displaced by a predetermined angle.
．． Third. Each time the code plates of... make one revolution, the third...
4th. ... are each rotated and displaced by a predetermined angle. Further, a code pattern corresponding to the rotation angle from the reference position of each code plate is read by each reading means, and the code pattern read by each reading means is used as an encoded signal corresponding to the rotation angle of the input shaft. Since the rotation angle is output, even if the input shaft rotates 360 degrees or more, the rotation angle can be detected.

"Embodiments" Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing the configuration of an embodiment of the present invention. In this figure, K1. K2 is a first-stage and second-stage rotation angle detection section, which is configured in the same manner as a conventional absolute value type rotary encoder. That is,
In the first and second stage rotation angle detection sections,
As shown in FIG. 2, the temporary codes C1 and Ct and the light projector 7. R2, and the detection unit S4. S2. Code board CI.

C2 is made of, for example, a circular metal plate, and has a slit pattern as shown in the figure. In this case, the slit pattern corresponds to the rotation angle from the reference position on each code plate C,,C, and is formed so that the pattern changes sequentially at each predetermined angle (hereinafter referred to as the minimum division angle). has been done. This minimum division angle determines the resolution of the code plates C+ and Ct themselves. Light projection part,,L.

is formed by arranging a plurality of light emitting elements (for example, light emitting diodes) in series, and the detection parts S, , S.

is formed by arranging a plurality of light receiving elements (for example, photodiodes) in tandem. The light projecting parts L1, L and the detecting parts S, , S, are arranged to face each other so as to sandwich the code plates C, , C, between them. On the other hand, ■ is an input shaft attached to the first stage code plate CI, and the rotation of the motor or load to be measured is transmitted to the code plate CI via this input shaft I. . Further, PM is a pulse motor that rotates and displaces the second stage code plate C2 stepwise by the minimum division angle. Further, 3 is a control circuit that controls the operation of the pulse motor PM based on the code pattern read from the code plate C1 by the detection unit S, and the first stage code plate C8 is rotated 360 degrees from the reference position in the normal rotation direction. Each time the second stage code plate C2 rotates, the second stage code plate C2 is rotationally displaced in the forward rotation direction by the minimum division angle, and conversely, the first stage code plate C2 is
Every time the stage code plate C3 rotates 360 degrees in the reverse direction from the reference position, the second stage code plate C2 is rotationally displaced in the reverse direction by the minimum division angle. Further, the collateral circuit 3 outputs the code pattern read by the detection units S+ and S2 as an encoded signal corresponding to the rotation angle of the input shaft l.

In the above configuration, the rotation of the motor or load to be measured is transmitted to the code plate C1 via the human power shaft l,
When the first stage code plate C1 makes one rotation in the normal rotation direction, the pulse motor PM rotationally displaces the second stage code plate C2 in the normal rotation direction by the minimum division angle. From now on, code board C1
However, every time the code plate C2 rotates once in the normal rotation direction, the pulse motor PM rotationally displaces the code plate C2 by the minimum division angle in the normal rotation direction.

Furthermore, every time the code plate C1 rotates once in the reverse direction, the pulse motor PM rotationally displaces the code plate C1 in the reverse direction by the minimum dividing angle. Then, a code pattern corresponding to the rotation angle from the reference position of each code plate C1, C2 is read out by the detection unit S l + 32, and the detection unit S,...
The code pattern read out in S2 is output from the control circuit 3 as an encoded signal corresponding to the rotation angle of the human power shaft l.

Here, for example, the rotation angle detection section K of the first stage.

If the resolution per rotation of 2 is 100, and the resolution per rotation of 2 is 50 for the rotation angle detection section of the second stage, then the rotation angle detection sections of the first and second stages have a The resolution of the combination of 2 is 100x50=5000
... (1). In addition, the range in which the rotation angle can be detected, in other words, the rotatable range of the input shaft l is the same as the resolution of the second-stage rotation angle detection section, and the thick bar θ)0i17-l+bow When going to A at Nguchi Pass, a plurality of rotation angle detection parts and pulse motors PM with the same configuration as in the second stage rotation angle detection part are provided, and by increasing the number of stages, the human power axis I It is possible to widen the rotatable range of the lens, thereby improving resolution. Organizing the above results as follows.

Resolution of the first stage rotation angle detection unit R1 Resolution of the second stage rotation angle detection unit R2 Resolution of the third stage rotation angle detection unit R3 Resolution of the Nth stage rotation angle detection unit If Rn is Rn, the resolution R for the measurement target (as seen from human power axis 1 and f2) is R= RI
-(2), the rotatable range of input shaft 1 N max
is Nmax=RtXR3X ・XRn −(3
).

According to the embodiment described above, 3
Since it is possible to detect rotation angles of 60 degrees or more,
The resolution of the measurement target can be improved, and
All the problems caused by using conventional speed reduction mechanisms can be eliminated.

In addition, in the above-mentioned embodiment, the code plates C1, C
2, the code pattern is recorded by slits, but the present invention is not limited to this. For example, the code pattern may be recorded by printing on the code plates CI and C2, and this code pattern may be read by a reflective photosensor. Alternatively, the code plates C,, C, may be replaced with magnetic disks, a code pattern may be magnetically written on the magnetic disk in advance, and the code pattern may be read by a magnetic reading head.

[Effect of the Invention J As explained above, according to the present invention, each code pattern is provided to be rotatable independently, and a code pattern corresponding to the rotation angle from each reference position is recorded in advance at each predetermined angle. an input shaft connected to the first code plate; and a driving means for rotationally displacing each of the second to Nth code plates by the predetermined angle in steps. , reading means provided corresponding to each of the first to Nth code plates and reading out the code pattern from each code plate; and a code read by the reading means corresponding to the nth (n≧1) code plate. n+ based on the pattern
A code pattern read out by each reading means by controlling a driving means corresponding to the first code plate and rotationally displacing the n+1th code plate by the predetermined angle every time the nth code plate rotates once. Since the control means for outputting the encoded signal as an encoded signal corresponding to the rotation angle of the input shaft is provided, the following effects can be obtained.

(2) Since rotation angles of 360 degrees or more can be detected without using a speed reduction mechanism, resolution can be improved.

■By changing the resolution of the code plate and the number of these stages, the rotatable range of the input shaft and the resolution for the measurement object can be changed arbitrarily.

■Only the first code plate needs to be connected to the axis to be measured via the manual axis, and the second and subsequent code plates can be installed in different locations, so installation is limited by location. Things will go away.

- Unlike the conventional method, there is no need to use a reduction mechanism, so there is no risk of detection errors caused by pitch errors and backlash of reduction gears.

■By increasing the number of stages of code plates, it is possible to secure the resolution for the measurement target even if the resolution of the code plates after the first stage is small, thus reducing the manufacturing cost when providing a code pattern on the code plate. Is possible.

■ Absolute value type rotary encoders need to align the origin at startup, but with conventional reduction mechanism, the input shaft rotates multiple times (for example, reduction ratio force q vs. 20
In the case of a reduction mechanism of You can align the origin with just

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing the configuration of an embodiment of the present invention;
FIG. 2 shows the rotation angle detection units K 1 , K 2 of FIG. 1. FIG. K1. K2...Rotation angle detection unit, C,
, C2... Code board, L, , L2...
・Light emitter, S, S2...Detector 1, PM...
...Pulse motor, 1...Input 1111.3...
...control circuit.

Claims (1)

[Claims] first to Nth code plates, each of which is independently rotatable and on which a code pattern corresponding to a rotation angle from each reference position is recorded in advance at each predetermined angle; and the first code plate. an input shaft connected to the second to Nth input shafts;
a driving means for rotationally displacing each of the code plates by the predetermined angle in a stepwise manner; a reading means for reading the code pattern from each code plate provided corresponding to each of the first to Nth code plates; controlling the driving means corresponding to the n+1th code plate based on the code pattern read by the reading means corresponding to the nth (n≧1) code plate;
Each time the n-th code plate rotates once, the n+1-th code plate is rotationally displaced by the predetermined angle, and the code pattern read by each reading means is converted into an encoded signal corresponding to the rotation angle of the input shaft. 1. An absolute value type rotary encoder, characterized in that it is equipped with a control means for outputting as follows.