JPH02126114A - Encoder - Google Patents

Abstract

PURPOSE:To improve the resolution of measurement by providing plural slit arrays at equal intervals and providing signal transmission/reception parts which lead out signals having 90 deg. phase difference to respective slit arrays. CONSTITUTION:A rotary slit plate 6 is provided with first and second slit arrays 16 and 18, and signal transmission/reception parts consisting of light emitting elements 14a and 14b, light receiving element 34a and 34b, light emitting elements 16a and 16b, and light receiving elements 36a and 36b are so provided that they face each other with slit arrays 16 and 18 between them. Output signals S1 and S2 having 90 deg. phase difference and output signals S3 and S4 having 90 deg. phase difference are led out from light receiving elements 34a and 34b and light receiving elements 36a and 36b in accordance with rotation of the rotary slit plate 6 and inputted to a signal processing part 32 and processed, and output signals S01 and S02 whose resolution is improved twice are led out to output terminals T1 and T2. Thus, the speed or the rotary angle of a rotary body or the length, the speed, or the like of a mobile object is measured with high resolution.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an encoder, and more particularly, an optical or magnetic speed sensor employing a slit plate such as a strip or a disc is used to encode a moving encoder. The present invention relates to an encoder that measures the length or speed of an object, or the rotational speed or angle of rotation of a rotating object.

[Background of the Invention] Recently, encoders using optical or magnetic speed sensors are often used to measure the length or speed of a moving object or the rotation speed or rotation angle of a rotating object. In this encoder, a linear speed sensor is used to measure the length or speed of a moving object, and
A Rochley type speed sensor is used to measure the rotation speed and rotation angle of a rotating object. For example, in a method using a linear optical speed sensor, a slit plate having slits of the same width arranged at equal intervals, or a glass plate with light-shielding parts spaced at equal intervals are printed using a silk screen or the like. The slit plate formed using this method is configured to be attached to a moving object. Then, as the slit plate moves, the light beam between the light receiving and emitting elements placed facing each other across the slit plate is interrupted, and the frequency of the signal derived from the light receiving element is measured using a counting circuit. The length or speed of a moving object is calculated by In addition, in the method of using a rotary type speed sensor, slits of the same width are arranged at equal intervals on a slit disk or a glass disk, and light shielding parts are printed at equal intervals by printing such as silk screen. The slit disk formed by the method is configured to be attached to a rotating object. Then, as the slit disk rotates, the light beam between the light receiving and emitting elements placed opposite each other across the slit plate is intermittent, and the frequency of the signal derived from the light receiving element is measured using a counting circuit or the like. The rotation speed and rotation angle of a rotating object are calculated.

However, in order to accurately measure the length or speed of a moving object or the rotational speed or rotation angle of a rotating object, that is, to improve the resolution, the encoder needs to narrow the width of the slit and It was necessary to form the separation distance to a smaller value. Therefore, the passage of the light beam passing through the slit is restricted, and the amount of light received by the light receiving element is reduced.As a result, the error rate increases in the processing of the signal derived from the light receiving element, and the measurement error, that is, This poses a problem in that errors are likely to occur in measured values such as the length or speed of a moving object or the rotational speed or angle of rotation of a rotating object.

[Object of the Invention] The present invention has been made to overcome the above-mentioned disadvantages, and includes a plurality of slit rows having the same pitch, and a phase difference of 90° between each slit row. A signal transmitting/receiving section is arranged to derive a signal obtained from the signal transmitting/receiving section, and based on the signal obtained from the signal transmitting/receiving section, the movement of the slit row or the signal transmitting/receiving section, that is, the relative movement speed of the slit row and the signal transmitting/receiving section is determined. An object of the present invention is to provide an encoder that can reduce errors in measurement values such as the length or speed of a moving object or the rotation speed or rotation angle of a rotating body, that is, improve resolution in measurement. purpose.

[Means for Achieving the Object] In order to achieve the above-mentioned object, the present invention includes a slit array of 2 degrees (n - a positive integer) in which light transmitting parts and light shielding parts are formed at equal intervals. at least one or more slit plates having a
A detection signal comprising a pair of signal transmitting/receiving sections and arranged so that each signal transmitting/receiving section derives a signal having a phase difference of 90 degrees based on relative movement between the slit row and the signal transmitting/receiving section. The present invention is characterized by comprising a deriving means, and a measurement signal forming means for forming and transmitting a signal indicating the relative moving speed of the slit array and the signal transmitting/receiving section from the signal derived from the detection signal deriving means.

[Embodiment] Next, a preferred embodiment of the encoder according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an optical rotary encoder according to the present embodiment, in which a rotary slit plate 6 and a shaft rod 8 whose center point is the same are fixed to the rotary slit plate 6. has been done. The shaft rod 8 is attached to a rotating object or a rotating drive mechanism (not shown), and is rotated or rotated at a required number of rotations. A light emitting unit 10 that is composed of an LED or the like and emits a light beam faces each other with the low crystal slit plate 6 in between, and a phototransistor that receives the light beam emitted from the light emitting unit 10 and derives a signal corresponding to the light beam. An output signal obtained by performing predetermined signal processing on a signal derived according to the incident situation of the light beam from the light receiving section 30 and the light emitting section 10 is output to the output terminal T+.
, and a light-receiving element deriving signal processing section 32 that sends out signals to T2.

The rotary slit plate 6 has a first slit row 16 and a second slit row 18 formed inside the first slit row 16. The first slit row 16 is a transparent section 16゜1.16゜2 to 16 that passes through the low slit plate 6 itself.
゜. and light shielding portions 16, 1.16, 2 to 16s, . Similarly, the second slit row 18 also includes light transmitting portions 18°1.18°2 to 18o7 and light shielding portions 1851.18s2.
to 18s1. including.

Further, the light emitting section 10 has a printed circuit board 14p, on which the light emitting elements 14a and 14b are arranged on the same horizontal straight line. In addition, the light emitting element 14
On the same horizontal line below a and 14b, a light emitting element 16a,
16b is provided. The light receiving section 30 has a printed circuit board 34p, and a light receiving element 34a is disposed on the printed circuit board 34p at a predetermined position where the light beam 4La emitted from the light emitting element 14a is incident.

Similarly, the light receiving element 34b is attached at a position where the light beam 40.5 from the light emitting element 14b is incident.

Furthermore, in the light receiving section 30, the printed circuit board 36p
A light receiving element 36a is disposed at a position where the light beam 6° from the light emitting element 16a is incident, and a light receiving element 36b is attached at a position where the light beam 6Lb from the light emitting element 16b is incident. .

And light emitting elements 14a, 14b and 16a116b
Predetermined voltages V and V2 are respectively applied to the light emitting voltage supply section 22 so that the light beams 4, La54, and Lb are emitted with a predetermined amount of light.

On the other hand, the output signals S+, 32, S3, and S4 derived from the light receiving elements 34a, 34b, 36a, and 36b are connected to be input to the light receiving element derived signal processing section 32, and the light receiving element derived signal processing section 32 has a resolution. The output signal S is doubled. , and S. 2 is the output terminal T,
, T2, and output signal S. , and S
. 2 is configured such that counting processing is performed in a counting processing section 56 and a display section 58, and the counting processing results are visually recognized as, for example, numbers.

Here, referring to FIG. 2, the light emitting elements 14a, 14b and 16a, 16b and the light receiving elements 34a, 34b and 36a
, 36b and the row slit plates 6 disposed therebetween are shown in FIG.
A detailed explanation will be given using a cross-sectional view taken along the line -nb'.

The first slit row 16 and the second slit row 18 are formed in transparent portions 16°1.1602 to 16.1, respectively. n and 18
oI, 1802 to 18°, and light shielding part 16. ．． ．． 1
6.2 to 16, and 18,1.18s2 to 1
8s, , are the same, but as shown in FIG. 2, the center line CI of the transparent part 16on and the transparent part 18. ,,
are spaced apart by a distance n from the center line C2, that is, all the light transmitting parts or light shielding parts are spaced apart by a distance n.

The distance n is a predetermined distance for obtaining a signal having a phase difference of 90°, which will be described later.

The first and second slit rows 16 formed in this way.
18, first, a light receiving element 34a is arranged so that the light beam 4 from the light emitting element 14a is incident thereon, and
Similarly, the light receiving element 34b is arranged so that the light beam 4Lb from the light emitting element 14b is incident thereon. Here, the output signal SI'J accompanying the movement of the first slit row 16 from the light receiving element 34a134b in the direction m shown in the figure, for example.
6 and S2 are spaced apart so that the phase difference between them is 90°.

Similarly, the output signals S3 and S4 derived from the light emitting element 16a and the light receiving element 36a, and the light emitting element 16b and the light receiving element 36b, which are arranged with the second slit row 18 in between, are also rotated at 90 degrees. They are arranged to have a phase difference.

On the other hand, since there is a shift between the first slit row 16 and the second slit row 18, that is, the distance n, the output signal S2 derived from the light receiving element 34b and the output signal S4 of the light receiving element 36b also have a phase difference of 90°. and is configured to be derived with

The light emitting voltage supply section 22 has a relatively stable voltage, for example, 5.
The configuration is such that the DC voltages V, , V, are derived. As shown in FIG.
a comparator 42 to which the output signal S2 derived from the light receiving element 34b is supplied, a comparator 46 to which the output signal S3 is input, and a comparator to which the output signal S4 is input. 48. and ratio type 4
2 and 44, and output signals sp3 and SF3 derived from comparators 46 and 48.
and an exclusive OR circuit 54 which is input manually.

Output signal S from exclusive OR circuit 52. , and the output signal S from the exclusive OR circuit 54. 2 are respectively obtained at the outputs T1 and T2, and the output signals S obtained there. 1 and S. 2 is, for example, the counting processing section 56
, the rotation angle or the number of rotations of the rotary slit plate 6 is calculated. Further, the rotation angle or the number of rotations obtained by the counting processing section 56 is configured to be visually recognized on a display section 58.

The operation and effects of this embodiment configured as described above will be explained. First, a DC voltage of, for example, 5V is supplied from the light emitting voltage supply unit 22 to the light emitting elements 14a, 14b and 16a, 16b, respectively, so that they enter a light emitting state, and a light beam 4 L1 is emitted from each of the light emitting elements 14a, 114b, 16a, 16b. % 4Lb and 6 Las 6Lb
is emitted. When the rotary slit plate 6 rotates, that is, moves in the direction of the arrow m as shown in FIG.
Output signals S and S2 having a 90° phase difference as shown in FIG. 1 are derived and supplied to comparators 42 and 44, respectively. Similarly, as shown in FIG. 4(6), output signals S3 and S4 having a 90° phase difference are derived from the light receiving elements 36a and 36b, and are supplied to comparators 46 and 48, respectively.

The comparators 42.44 and 46.48 produce a 9-waveform signal formed into a square wave, as shown in FIGS.
Output signal SP1% SF3 and S with 0° phase difference
r1 and spa are derived. and output signals SPI and S
F3 is supplied to the exclusive OR circuit 52, and as shown in FIG. 4, an output signal SO'l having a waveform with a period twice that of the output signal SPI or SF3 is obtained. Similarly, from the output signals SP3 and SF3, FIG.
The output signal S shown in 2 is obtained, and this output signal S. 1 and S. 2 has a phase difference of 90°.

In this way, the derived output “signals S.l and S
. 2 are respectively counted on the time axis in the counting processing section 56, and the rotation angle or rotation number of the row slit plate 6 is calculated. Further, the rotation angle or the number of rotations obtained by the counting processing section 56 is displayed on the display section 58 so as to be visually recognized.

In the embodiment described above, the transparent portions 16 of the first and second slit plates. ,．． 18oI, and the light emitting elements 14a, 14 are arranged so that a distance n is spaced between the center lines C2 and C2 of the
b, 16a, and 16b are arranged so as to have a phase difference of 90°, but the present invention is not limited thereto. For example, assuming that the center lines C8 and C2 are the same,
The same effect can be obtained even if the light emitting elements 14a and 14b and 16a and 16b are spaced from each other at a distance equal to the distance n. Further, the present invention also includes arranging light emitting and light receiving elements in two or more slit rows in the same manner to further improve the resolution.

Further, in this embodiment, an optical rotary type encoder using a light emitting element and a light receiving element has been described, but the present invention is not limited to this, and linear type slits may be used.
Alternatively, instead of the optical sensor, the slit plate may be made of a ferromagnetic material or a magnetizing material, and a Hall IC1 magnetoresistive element (MR element), a saturable core, etc. may be used as the detection element. Of course.

[Effects of the Invention] As described above, according to the present invention, a plurality of slit rows having the same pitch are provided, and each slit row is provided with a signal to derive a signal having a phase difference of 90°. A transmitter/receiver is provided, and the slit row or the signal transmitter/receiver is moved based on the signal obtained from the signal transmitter/receiver, that is,
By detecting the relative movement speed between the slit row and the signal transmitting/receiving section, it is possible to reduce errors in measurement values such as the length or speed of a moving object, or the rotation speed or rotation angle of a rotating body, in other words, to improve the resolution in measurement. It has the effect of improving.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments.
Of course, various improvements and changes in design are possible without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the configuration of an embodiment of the encoder according to the present invention, and FIG. 2 is a perspective view showing the structure of the encoder shown in FIG. 1.
3 is a circuit block configuration diagram for explaining signal processing of the encoder shown in FIG. 1, and FIG. 4 is a cross-sectional view taken along the line nb-nb'. FIG. 3 is a waveform diagram showing signal waveforms and their timing in a derived signal processing section. 6...Low-crislit board group...Light-emitting parts 14a, 14b, 16a, 16b...Light-emitting element 1
6... First slit row 16o1-16. ,...
・Transparent part 16, l~16. ,,... Light shielding part 18
. . . Second slit rows 18o1 to 18o, . . . Transparent portions 18,1 to 18s- . . . Light blocking portion 22 . . . Voltage supply unit for light emission 30 . . . Light receiving portion 32 . Derived signal processing units 34a, 34b, 36a, 36b...light receiving element 42.
44.46.48... Comparator 52.54... Exclusive OR circuit

Claims (1)

[Claims] (1) At least one slit plate having 2^n (n = positive integer) slit rows in which light-transmitting parts and light-shielding parts are formed at equal intervals, and facing each other with the slit row in between. Two pairs of signal transmitting/receiving sections are provided, and each signal transmitting/receiving section derives a signal having a phase difference of 90° based on relative movement between the slit row and the signal transmitting/receiving section. a detection signal deriving means disposed in the detection signal deriving means, and a measurement signal forming means for forming and transmitting a signal indicating the relative moving speed of the slit array and the signal transmitting/receiving section from the signal derived from the detection signal deriving means. An encoder comprising: