JPS6236923A - Optical encoder - Google Patents

Abstract

PURPOSE:To reduce the radial size of a turning slit board by providing a phase Z and the inverse of phase Z representing a turning signal and arranging the phase while sandwiching a pattern for phases A/B so as to operate differentially a photodetection section of the phase Z and the inverse of phase Z. CONSTITUTION:A fixed slid board 20 consists of slit patterns of the Z phase 31 at the inner periphery part, the inverse Z phase 32 at the outer periphery part and the A phase 35, the inverse of A phase 36, the B phase 33 and the inverse of B phase 34 at the intermediate part respectively. The radial size of the phase Z and the inverse of phase Z is halved regardless of the same output by arranging the A phase 31 and the invese of Z phase 32 so as to sandwich the phatterns 33-36 for the phases A/B and the entire size is not increased by providing the patterns of the Z phase 31 and the inverse of Z phase 32. As a result, the idle space of the lighting space of a LED is utilized and the size of the Z phase 31 and the inverse of Z phase 32 is halved by eliminating a reference phase Z as a/2, b/2 respectively.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to optical encoders.

The optical encoder according to the present invention is used, for example, for detecting the rotation of a servo motor in the field of numerically controlled machine tools.

[Prior art and problems to be solved by the invention]

Generally, an optical rotary encoder includes a light emitting element such as a light emitting diode LED, a rotary code plate fixed to a rotating shaft, a fixed code plate opposing the rotary code plate, and a light receiving element. The light from the light emitting element passes through a light transmitting section provided on the rotary code plate and a slit provided on the fixed plate, is received by the light receiving element, and is converted into an electrical signal, thereby detecting the rotation angle and rotation position of the motor, etc. The light transmitting portion of the rotating slit plate consists of a plurality of concentric code patterns and a reference pattern, and the slits of the fixed plate are provided corresponding to each code pattern and reference pattern, respectively.

As shown in FIG. 9, the conventional rotary slit plate has A, τ, B, and B phases for generating count signals and a Z phase for generating one revolution signal. In addition, there are two light sources (usually LEDs), one for A phase/B phase and one for 2 phase (LHDI' in the figure).
, LED2) or three for each phase (LHDI, L
ED2, LED3) were used.

Also, the pattern of the code board is Z-phase and Z-phase reference (ZR
), and since these patterns are arranged in the radial direction of the code plate, the code plate has a disadvantage in that the outer size of the code plate becomes large.

Figure 10 shows the A phase and τ phase (1) in Figure 9, and the B phase and τ
It shows the light receiving element output waveform of phase (2), and also shows the pulse waveform generated once per rotation, which is waveform-shaped with the Z phase reference window and the Z phase light receiving element output waveform.

Conventional structures have not been able to meet the demands of reducing the external size of optical encoders and improving detection accuracy. That is, even if a plurality of light sources are used, there is a problem in that errors are likely to occur in the output signal due to leakage of light that has passed through the code pattern.

An object of the present invention is to provide a Z phase and a τ phase representing a rotation signal, and to provide an A phase/
The purpose is to dispose the B-phase pattern in between and to differentially operate the Z-phase and -2-phase light receiving sections.

[Means and operations for solving the problems] In the optical encoder provided by the present invention to achieve the above object, Z
Phase, τ phase (inverted Z phase) are arranged, and the Z phase is sandwiched between the fixed slit of the same pattern for the Z phase and the 7th phase, and the pattern for the A phase/B phase.

It is characterized by having a rotating slit in which the τ phase is arranged and the Z phase and the τ phase form a black and white opposite pattern.

In the device of the present invention, the conventional ZR phase representing the reference rotation is no longer necessary, the dimensions of the rotating slit plate are reduced, and the space corresponding to the LED can be used effectively, and the LED of the local illumination light source can be used more effectively. It becomes possible to reduce the number of pieces.

As a result of the ZR phase (Z reference phase) becoming unnecessary, it is possible to obtain the same output as long as the Z phase and -2- phase (inverted Z phase) have % of the conventional dimension in the radial direction. However, the provision of the Z and τ phases has the advantage that the dimensions do not increase.

〔Example〕

Embodiments of the present invention will be described in detail using the drawings.

FIG. 1 is a plan view showing a rotary slit plate in an optical encoder as an embodiment of the present invention. In FIG. 1, a rotary shaft hole 11 is provided at the center C, and the rotary slit plate 10 is fixed to the rotary shaft of the encoder via a holding plate (not shown) or the like. Reference numeral 12 denotes a Z-phase part bone, and the one provided at the outer edge of the rotating slit plate via the intermediate part 14 corresponding to the A, B, τ, and T phases of the fixed slit plate is an inverted Z-phase (τ-phase) part 13. It is.

FIG. 2 is a sectional view of an optical encoder using the rotary slit plate 10 of FIG. 1. In FIG. 2, the rotating slit plate 10 attached to the rotating shaft 21 of the servo motor through the opening 11 is illuminated by a light emitting diode LED 22 as a light source powered by a power source, and the light transmitting portion of the rotating slit plate pattern The light that has passed through further passes through the light transmitting part of the fixed slit plate 20, is photoelectrically converted in the light receiving part 24 using a photoelectric conversion element, and is guided to the output part using a conductive wire or an optical fiber. In this case, the light source 22 is generally equipped with an optical element 23 such as an optical lens for forming parallel light beams.

Figure 3 shows the LErl of the fixed slit plate in the equipment shown in Figure 2.
FIG. Third
In the figure, the fixed slit plate 20 is formed with a Z-phase 31 at the inner edge, an inverted Z-phase 32 at the outer edge, and two slit patterns on the left and right in the middle, respectively. That is, an A phase 35, an inverted A phase 36, a B phase 33, and an inverted B phase 34. A feature of this fixed slit pattern is that the Z phase 31 and the τ phase (inverted Z phase) 32 have the same pattern (FIG. 7).

FIG. 4 is a diagram showing signal output waveforms in the device shown in FIG. 2. When the light-receiving elements 44 and 45 are connected as shown in FIG. 5, the light-receiving elements 44 and 45 that receive the transmitted light of the Z phase and the inverted Z phase (τ phase) operate differentially, resulting in the operational amplifier output. is shown in FIG.

The Z Wako optical element output S (41) and the inverted Z phase (τ phase) light receiving element output S (42) intersect at a crossover point 43, where the output waveform S (40) of one pulse per revolution is obtained after shaping. It will be done.

In the device shown in Fig. 2, the conventional Z-phase reference is abolished, and the light-receiving elements corresponding to the Z-phase and inverted Z-phase (Z-phase) are operated differentially, and the A-phase/B-phase Since the Z phase and the two reversed phases are arranged to sandwich the pattern, it is possible to obtain the same output as long as the radial dimension of the Z phase and the reversed Z phase is about 2 times the conventional dimension. By providing the inverted Z-phase pattern, the overall dimensions do not increase. As a result, the conventional use of empty space in the lighting space of the light emitting diode LED can be reduced, and by eliminating the reference Z phase, the dimensions of the Z phase 3LZ phase 32 can be halved as shown in FIG. Each radial half of the conventional type is a/2. b/2.

Therefore, conventionally two or three light sources were required, but with only one light source, Z phase 31, T phase 32, A/B
It becomes possible to illuminate the entire target area of the phases 33 , 34 , 35 , 36 . In other words, by reducing the LED lighting coverage area, L[! The number of D used can be reduced.

It also allows for effective use of LED compatible space. In an optical encoder, the A phase/B phase (and its inverted phase) for counting are the most important, and in the device shown in Figure 2, the A phase and B phase are the most important.
The phase or its inverse phase can be made to correspond to the center of the LED, and furthermore, the Z phase and the inverted Z phase can be operated to correspond to the edges of the LED without much disadvantage.

Furthermore, in the past, there was a possibility that light leakage through the window of the reference Z phase would enter the Z phase and cause an error, but in the present invention, the reference Z phase can be omitted, and the Z phase of reduced size and Inversion Z
In order to reduce such accuracy errors by combining the phases, the central peak of the force characteristic curve means the maximum amount of LED light.

FIGS. 7 and 8 show developed views of the rotating slit and fixed slit patterns of the optical encoder shown in FIGS. 1 and 3, respectively.

FIG. 7 shows the pattern of the fixed slit Z phase and inverted Z phase, and the Z phase and inverted Z phase show the same pattern, and from the left to the right, the pattern is 3+2:1:1:2. :2:6:2:
They are distributed in a 3:1 ratio.

FIG. 8 shows a pattern of a Z phase and an inverted Z phase of the rotating slit, and in this case, the Z phase and the inverted Z phase in each frame have a structure in which the brightness and darkness are reversed. The dimensional ratio is the same as in FIG.

[Effects of the Invention] According to the present invention, Z representing a rotation signal of one pulse per revolution
The Z phase and the inverted Z phase are arranged so as to sandwich the A phase/B phase pattern for counting, and the conventional standard Z phase is omitted and the radial direction of the Z phase and the inverted Z phase is By halving the dimensions, it became possible to reduce the radius dimension of the entire rotary slit plate.

Furthermore, by connecting the Z-phase and inverted two-phase light receiving elements for differential operation, the reference Z phase can be omitted, and from this point of view, it is also possible to reduce the diameter of the rotating slit plate9). Ta.

In addition, if the radial dimension of the Z phase and inverted Z phase is % of the conventional dimension, it is now possible to obtain the same output, and the Z phase
By providing the phase and inverted Z phase, the dimensions do not increase, and by reducing the diameter of the slit plate, the light source L
The number of ED cylinders used can now be reduced from 2 or 3 to 1.

[Brief explanation of drawings]

Fig. 1 is a plan view of a rotating slit plate pattern of an optical encoder according to the present invention, Fig. 2 is a cross-sectional view of the main part of the optical encoder, and Fig. 3 is a pattern of the illuminated part of the fixed slit plate of Fig. 2. Figure 4 is a signal output waveform diagram of the device shown in Figure 2, Figure 5 is a connection circuit diagram of the light receiving element in Figure 2, Figure 6 is a light intensity distribution diagram of the light source LED, and Figure 7 is the diagram of Figure 2. 8 is a developed view of the rotating slit pattern, FIG. 9 is a diagram showing the pattern of the illuminated part of the conventional rotating slit plate, and FIG. 10 is the A/B phase and Z phase of FIG. 9. A phase light receiving element output waveform diagram and a pulse waveform diagram for the reference Z phase are shown, respectively. 10...Rotating slit plate 11...Opening hole 12 of 10...Z phase 13 of 10...T phase 14 of 10...A/B phase corresponding intermediate portion 20...Fixed slit plate 21 ...Servo motor rotation shaft 22...Light source LED 23...Optical element 24 of 22...Light receiving element 31...Z phase 32 of fixed slit plate... -2-phase 33...
B phase 34... τ phase 35... A phase 36... τ phase S (41)...Z phase output waveform S (42)...T phase output waveform 43...・Z and T phase output crossover points 44 and 45
... Light receiving elements 46, 47, 4B, 49, 50... Resistor 5
1...Operation amplifier patent distributor Fanasoku Co., Ltd. Patent application agent

Claims (1)

[Claims] A, B with light transmitting and non-transmitting parts arranged concentrically,
In an optical encoder having Z phase patterns, the patterns are arranged in such a way that the A phase and B phase patterns as count signal generation patterns are sandwiched by the Z phase and inverted Z phase patterns as one revolution signal generation patterns. An optical encoder characterized by: