JP2002286508A - Outputting method for sine wave encoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide stable sine wave signals by correcting detected rotation signals by closed-loop feedback in analog form. SOLUTION: According to this outputting method for a sine wave encoder, the detected rotation signals (Asinθ+Δs, Bcosθ+Δc) are inputted into a correction part 20 having correction coefficient calculation parts 44 and 44A in a closed loop and there at least their offsets and amplitudes are corrected in the form of analog signals. Angle outputs 15 are inputted into ROMs 80 and 81 and encoder outputs (sinϕ, cosϕ) are obtained from ROM tables.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for outputting a sine wave encoder, and more particularly, to a method for correcting a two-phase rotation detection signal with high accuracy by correcting at least an amplitude and an offset in a state where a closed loop is formed for an analog signal. It relates to a new improvement for obtaining an encoder output.

[0002]

2. Description of the Related Art Conventionally, as a method of outputting a sine wave encoder of this kind, a configuration of a first conventional example shown in FIGS. 3 and 4 has been adopted. That is, in FIG.
A first substrate which is rotatable via A
The substrate 1 is provided with a light receiving element 3. Above the rotation code plate 2, a second substrate 5 having a light emitting element 4 is fixedly disposed via a frame (not shown), and a fixed slit is provided between the rotation code plate 2 and the light receiving element 3. 6 are provided. A first amplifier 7 and a second amplifier 8 are connected to the light receiving element 3, and light from the light emitting element 4 is turned by the rotation of the rotary code plate 2 into a slit (not shown) and a fixed slit of the rotary code plate 2. 6 to the light receiving element 3 via
The first and second rotation detection signals sin are analog sine wave signals having different phases from the amplifiers 7 and 8.
θ and cos θ are output.

Further, in the configuration of the second conventional example shown in FIG. 4, each of the rotation detection signals sinθ and cosθ is
Actually, errors Δs and Δc such as amplitude and offset are included, so that Asin θ + Δ
s and Bcos θ + Δc, through the first and second A / D converters 10 and 11, the first and second amplitude / offset correction units 1
2 and 13, the amplitude and offset are corrected, the angle is calculated by an angle calculator 14, and a digital angle output 15 is obtained.

[0004]

The output method of the conventional sine wave encoder has the following problems because it is configured as described above. That is, in the case of the first conventional example shown in FIG. 3, each rotation detection signal obtained from the light receiving element is merely amplified by an amplifier, and no correction such as amplitude and offset is performed. Accuracy was to be reduced. Further, in the case of the second conventional example shown in FIG. 4, since each rotation detection signal including an error is A / D converted and converted into a digital form, the amplitude and offset are corrected, and the angle is calculated. It is only possible to perform correction in digital form, and it is possible to output only a digitally changed waveform change, and it is impossible to obtain an encoder output corrected in a natural sine wave form in analog form.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in particular, by correcting at least the amplitude and offset of a two-phase rotation detection signal while forming a closed loop with respect to an analog signal. It is an object of the present invention to provide an encoder output method capable of obtaining a highly accurate encoder output.

[0006]

In the output method of the sine wave encoder according to the present invention, first and second rotation detection signals each having a different phase and an analog signal are obtained from a light receiving element by rotation of a rotation code plate. In the output method of the sine wave encoder, the first and second rotation detection signals are input to a correction unit having a correction coefficient calculation unit in a closed loop, and at least offset and amplitude correction is performed using an analog signal. The first and second corrected rotation detection signals A ′ sin θ and B ′ cos θ are input to an angle calculation unit to obtain an angle output, and the angle output is converted to first and second ROMs.
To the first and second ROM tables from the ROM table of the ROM.
In this method, encoder outputs sinφ and cosφ are output, and the first and second encoder outputs sinφ and cosφ output from the ROM are fed back to the angle calculation unit as correction reference signals.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an output method of a sine wave encoder according to the present invention will be described below with reference to the drawings. The same or equivalent parts as those in the conventional example will be described with the same reference numerals. 1, the first and second rotation detection signals sinθ and cosθ obtained by the encoder 30 shown in FIG. 3 actually include errors Δs and Δc such as offset and amplitude. Therefore, each rotation detection signal Asinθ + Δs, Bcosθ +
The correction unit is input as Δc.

The correction section 20 is configured as shown in FIG. That is, the analog first rotation detection signal Asinθ + Δs input to the correction unit 20 is corrected via the first offset correction unit 40 and the first amplitude correction unit 41 including a well-known comparison circuit and the like, and then the first correction is performed. The A / D converter 42 converts the analog signal into a digital signal and outputs it as the post-rotation detection signal A'sinθ. The first offset correction unit 40 and the first amplitude correction unit 41 digitize a part of the first corrected rotation detection signal A′sin θ via an A / D converter 43 and convert the digitized data into a first correction coefficient calculation unit. 4
4, the first offset correction signal 44a and the first amplitude correction signal 44b calculated by the first correction coefficient calculator 44 are input, and feedback correction using an analog signal by a closed loop is performed. Accordingly, the first offset correction unit 40 corrects the offset of the first rotation detection signal Asin θ + Δs, and the first amplitude correction unit 4
At 1, the amplitude of the first rotation detection signal Asin θ + Δs is corrected. The first correction coefficient calculation unit 44 has a built-in correction coefficient calculation program that is set in advance, and based on the value of the first corrected rotation detection signal A ′ sin θ, the correction signals 44a, A well-known addition / subtraction process is performed to obtain 44b.

The first rotation detection signal Asin θ + Δs is processed as described above as a first phase signal and output as a first corrected rotation detection signal A ′ sin θ, but as a second phase signal having a different phase from this. Second rotation detection signal Bc
os θ + Δc is the first rotation detection signal Asin θ +
The second offset correction unit 40A, the second amplitude correction unit 41A, and the A / D converter 42, which are configured in exactly the same manner as the processing system
A, 43A, the second offset correction signal 44a 'and the second
The offset and amplitude are similarly corrected by a closed loop using the amplitude correction signal 44b '.

The first and second corrected rotation detection signals A ′ sin θ and B ′ cos θ whose offset and amplitude have been corrected by the correction unit 20 are input to a well-known angle calculation unit 14 and output to an actual angle output 15. Is output. This angle output 15
Is input to the first and second ROMs 80 and 81 for two phases,
The first and second encoder outputs sin from the ROM tables (not shown) preset in the respective ROMs 80 and 81 according to the angle output 15 from the respective ROMs 80 and 81.
φ and cos φ are output. Therefore, the angle output 15
Are the corrected rotation detection signals A 'sin θ, B' cos
Since the angle output 15 is obtained based on θ, the encoder outputs sinφ and cosφ can also be obtained accurately. In addition, although shown by the dotted line in FIG.
As 0, it is fed back to the angle calculation unit 14 and the angle output 15
Accuracy can be improved.

[0011]

The output method of the sine wave encoder according to the present invention is configured as described above, so that the following effects can be obtained. That is, each rotation detection signal having an error component is subjected to feedback correction in a closed circuit using a correction coefficient calculation unit in an analog format, and offset and amplitude are corrected in an analog format. Can also be significantly improved. Also,
Since the angle information is read from the ROM table of the ROM based on the corrected angle output to obtain the encoder output, the final encoder output with higher accuracy than before can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main part of an output method of a sine wave encoder according to the present invention.

FIG. 2 is a block diagram illustrating a specific configuration of a correction unit in FIG. 1;

FIG. 3 is a configuration diagram illustrating a schematic configuration of an encoder according to the related art and the present invention.

FIG. 4 is a block diagram showing another conventional example.

[Explanation of symbols]

2 Rotation code plate 3 Light receiving element Asinθ + Δs, Bcosθ + Δc First and second rotation detection signals A′sinθ, B′cosθ First and second corrected rotation detection signals 20 Correction units 44 and 44A First and second correction coefficient calculation units 14 Angle calculation unit 15 Angle output 80, 81 First and second ROM sinφ, cosφ First and second encoder output 100 Correction reference signal

Claims (2)

[Claims] 1. A light receiving element (3) by rotation of a rotation code plate (2).
From the first and second rotation detection signals (A sin θ + Δs, B cos θ + Δ
c), wherein the first and second rotation detection signals (A sin θ + Δ
s, Bcos θ + Δc) is input to a correction unit (20) having a correction coefficient calculation unit (44, 44A) in a closed loop, and at least offset and amplitude correction is performed using an analog signal. The first and second corrected rotation detection signals (A 'sin θ, B' cos θ) are input to an angle calculation unit (14) to obtain an angle output (15). 2 Input to the ROM (80, 81) and read the ROM (80, 81)
The first and second encoder outputs (si
(nφ, cosφ) is output. 2. The first and second encoder outputs (sin φ, cos φ) output from the ROM (80, 81) are:
The method according to claim 1, wherein the signal is fed back to the angle calculator (14) as a correction reference signal (100).