JPH0329818A - Rotary encoder - Google Patents

Abstract

PURPOSE:To detect a light in a quantity corresponding to a slit width by an angle detection sensor and thereby to detect an absolute angle of a slit disk by a method wherein each slit in a slit line on the slit disk is set in a different slit width from others in accordance with the absolute angle of the slit disk. CONSTITUTION:When slits 2a and 3a of slit lines 2 and 3 pass an angle detection sensor 4 with rotation of a slit disk 1, light-sensing elements 7 and 8 sense lights from light-emitting elements 5 and 6 and an output voltage of each of them varies. This voltage is passed through an A/D converter and latched as a digital value in a control element. A detected digital value (one-degree signal) relating to the slit line 2 and obtained by the light-sensing element 8 repeats 0 and 1 at an interval of one degree of the central angle of the disk 1. On the other side, a digital value (ten-degree signal) relating to the slit line 3 and obtained by the light-sensing element 7 turns to be 0, 1, 0, 2, 0, 3, 0,..., 18, 0 at an interval of ten degrees of the central angle of the disk 1. In this way, an absolute angle of the disk 1 can be detected.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a rotary encoder capable of detecting the absolute angle of a rotating body, and particularly to a rotary encoder suitable for use in detecting the phase of a crankshaft of an engine. Regarding.

[Prior art] Absolute angle of a rotating body such as an engine crankshaft (
A rotary encoder is used to detect the phase), and the rotary encoder includes a slit disk attached to a rotating body and a slit 1 provided on the slit disk to detect light passing through it. Some devices are equipped with an angle detection sensor that detects the absolute angle of the slit disk.

A plurality of slits (180 slits) are provided on the slit disk at intervals of 1° from the center angle on the same circle of the slit disk.
Arranged, but excluding l of these 179
The slits (this is defined as a slit every 1°) are set to the same size, but the remaining one (this is defined as a slit every 360°) is set to a different size from these.

The angle detection sensor includes a light emitting part (light source) and a light receiving part, which are arranged to face each other on both sides of the slit 1/disk where slit rows every 1° and slits every 360° are provided. There is.

When the slit of the slit disk comes to the angle detection sensor, the light from the light emitting section passes through the slit, so the light receiving section receives the light and detects that the slit has passed.

The angle detection sensor outputs a 1° signal when it detects passing through the slits in every 10 slit row, and outputs a 360° signal when it detects passing through the slits every 360°.

When a 360° signal is received, the count is reset and the next 1° signal is counted in order.
The absolute angle of the slit 1 and the disk (therefore, the absolute angle of the rotating body) can be detected in units of 1°.

[Problem to be solved by the invention] However, in the above-mentioned conventional rotary encoder,
If the passage of the slit every 360° is mistakenly detected due to disturbances such as ignition noise or other switch noise, the system will never detect the passage of the slit every 360° until it makes one rotation (rotation 360°) and detects the passage of the slit every 360°. There is a problem that the angle cannot be detected.

The present invention was devised in view of such problems, and
It is an object of the present invention to provide a rotary encoder that can reliably detect an absolute angle even when subjected to disturbances such as noise.

[Means for Solving the Problems] For this reason, the rotary encoder of the present invention includes a slit disk having an annularly arranged slit row and attached to a rotating body, and a rotary encoder that passes through each slit in the slit row. In a rotary encoder equipped with an angle detection sensor that detects the absolute angle of the slit and disk by detecting the light that is generated by The plurality of slits are each set to a different slit width depending on the absolute angle of the slit disk, and the angle detection sensor detects an amount of light according to the slit width of the slit to detect the slit. It is characterized in that the structure-3-4 is configured so that the absolute angle of the slit disk can be detected based on the amount of light.

[Function] In the rotary encoder of the present invention described above, since each slit 1 to 1 in the slit row on the slit disk are set to different slit widths depending on the absolute angle of the slit disk, angle detection is possible. A sensor detects an amount of light corresponding to the slit width of the slit 1, and detects the absolute angle of the slit disk based on this amount of light.

[Example] Hereinafter, a rotary encoder as an example of the present invention will be explained with reference to the drawings. Fig. 1(a) is a front view thereof, Fig. 1(b) is a side view thereof, and Fig. 2 is an angle thereof. FIG. 3 is a circuit diagram of the detection sensor, FIG. 3 is an output characteristic diagram of a light receiving element of the angle detection sensor, and FIGS. 4(a) and (b) are diagrams showing output signals of the angle detection sensor.

Figure 1(a). As shown in (b), the present-day encoder includes a slit disk 1 attached to a rotating body (here, the crankshaft of the engine) (not shown), and an angle sensor that detects the absolute angle of this slit disk 1. It is equipped with a sensor 4.

Each slit disk l has slits j and rows 2 and 3 arranged on two concentric circles around its center.

Among these, one row of slits 1 2 is a slit row every 1°, and is composed of a plurality of (180 in this case) slits 2a arranged every 1° of the center angle of the slit disk 1. It has been. The 1° slits 2a are each set to have a size equivalent to 1° of the central angle in the circumferential direction, and are set to have the same size in the radial direction.

The slit row 3 is a slit row every 10', and is composed of a plurality of (18 in this case) slits 3a arranged every 10° from the center angle of the slit disk 1. ing. Each 10° slit 3a is set to a size equivalent to a central angle of 10° in the circumferential direction.
In the radial direction, the sizes are set to be different from each other.

In this example, the radial size of the 18 10° slits 3a is set to gradually increase as the rotation progresses when viewed from the angle detection sensor 4.

Here, the absolute angle of the slit disk l is 0° to 100°.
,20'~30''',400~50''...,34
Slits 3a are provided at positions ranging from 0" to 350 degrees, and these slits 3a are arranged in this order as the first...
Name the 2nd, 3rd, ..., 18th slit.

If the radial size of the first slit 3a is l, then the radial size of each of the second, third, fourth,..., eighteenth slits 3a is 2, 3, 4, respectively. ，
...It is set to l8.

On the other hand, the angle detection sensors 4 are provided on both sides of each circumference where the slit rows 2 and 3 of the slit disk 1 are provided so as to sandwich each circumferential portion. This angle detection sensor 4 includes light emitting parts (light sources such as LEDs or light bulbs) 5 and 6 and a light receiving part (
The light-emitting part 5 and the light-receiving part 7 are provided on both sides of the slit row 3 so as to face each other, and the light-emitting part 6 and the light-receiving part 8 are provided on both sides of the slit row 2 so as to face each other. Among these, the light emitting part 5 and the light receiving part 7 are larger than the largest one in the radial direction among the 10' slits 3a.

The light-receiving element 7 (or 8) as a light-receiving section has an electrical resistance that decreases when it receives light, and as shown in FIG. 2, it is connected in series with a resistor R, and Photodetector element 7 (8) when a constant voltage is applied to element 7 (8)
The voltage applied to A/
The output voltage Vcc is converted into a digital value according to the amount of decrease through the D converter (for example, one with a capacity of about 5 to 6 bits) 9, and the control unit 10 converts the slit disk 1 based on this digital value. It is now possible to calculate the absolute angle (and therefore the absolute angle of the crankshaft).

For example, the output voltage Vcc of the light receiving element 7 for detecting every 10' slit row 3 has a waveform as shown in FIG. In addition, the output voltage Vcc of the light receiving element 8 that detects the slit row 2 every 1' has a waveform that repeats the reference voltage (voltage when no light is received) and reduced voltage (voltage when light is received) at 1° intervals. Become.

Since the rotary encoder as an embodiment of the present invention is constructed as described above, when the slit disk 1 rotates together with the rotating body, the slits in each slit row 2 and 3
When a and 3a pass the angle detection sensor 4, the light receiving part 7
, 8 receive the light from the light emitting parts 5 and 6, and each output voltage ■
CC changes.

This output voltage Vcc is taken into the control section 10 through the A/D converter 9 as a digital value with waveforms shown in FIGS. 4(a) and 4(b).

As shown in FIG. 4(a), the detected digital values (1° signal) regarding the slit row 2 obtained by the light receiving unit 8 are calculated at every 1° central angle of the slit disk 1 (that is, the angle of the crankshaft). O (value when no light is received) and 1 (value when light is received) are repeated 8 times.

On the other hand, the detected digital value (10° signal) regarding the slit row 3 obtained by the light receiving unit 7 is as shown in FIG.
angle) 0.1, 0, 2, 0, 3, O, every 10°
..., 18, O.

In other words, since the 18 slits 1-38 of the slit row 3 are set in 18 steps so that the size in the radial direction gradually increases, the amount of light passing through the slit 3a also gradually increases, resulting in its output. The amount of change in voltage vcc is the third
As shown in the figure, the absolute angle of the slit disk l (absolute angle of the crankshaft) is O°~10', 20'~30
It becomes larger as the angle increases from 0, . . . 3400 to 350°. Therefore, the digital output value is also
As shown in Figure (b), when the absolute angle of the slit disk 1 (absolute angle of the crankshaft) is between O° and lO0, the angle is 1.
When the angle is from 20' to 30°, it increases to 2, and when it is from 3400 to 350°, it increases to 18, and the slit disk 1 (therefore, the crankshaft) rotates 360°, and the angle increases from 00 to 10'.
When the position is reached, the digital output value also returns to 1.

Therefore, based on the slit row 3, the slit disk 1 is
(that is, the crankshaft) can be detected.

In this way, based on the detection data every 200 based on the slit row 3 and the detection data every 1° based on the slit row 2, the diagonal angle of the slit disk 1 (that is, the crankshaft) is adjusted in units of 1°. It can be detected.

In particular, since the absolute angle of the slit disk 1 (crankshaft) every 20' can be determined absolutely from the magnitude of the digital output value, even if the slit 2a of the slit row 2 is incorrectly detected every 1 degree, at least 20' The absolute angle of the slit disk 1 (crank shirt 1~) can be detected in units of ''.

Therefore, it is possible to reliably cope with the control of fast phenomena and contribute to improving control accuracy.

In addition, since this rotary encoder detects the absolute angle by digitally converting analog data called light intensity, the angle detection sensor 4 may be affected by changes in light intensity due to voltage changes, dirt, deterioration, etc. For each 10" slit 1-3a, the digital output value from 340' to 350" is 18, while the digital output value from 00 to 10° is 1, which is an extremely large decrease, so the light amount in this part is Almost unaffected by change. Therefore, by detecting large changes in this digital output value and dividing this amount of change into 18 equal parts, even if the amount of light changes, it is always possible to correct this and detect absolute angles every 200. Become.

Here, slit rows 3 with different sizes of slits 1 are provided at 100 intervals by dividing 3600 into ↓8 equal parts, but the slit rows 3 can be set at 360 degrees depending on the purpose of use. It is also possible to divide it into appropriate equal parts and provide an appropriate angular interval ↓.

Furthermore, the radial size of the slits 3a is not limited to that of this embodiment, as long as they can be distinguished from each other.

-11 -12 Also, regarding slit row 2, depending on the purpose of use, ■
Things that are not at 0 intervals (for example, 2° intervals or 0.5° intervals)
You may also do so.

Furthermore, the rotating body is not limited to the crankshaft.

[Effects of the Invention] As detailed above, according to the rotary encoder of the present invention, a slit disk having an annularly arranged slit row and attached to a rotating body, and each slit in the slit row In a rotary encoder equipped with an angle detection sensor that detects the absolute angle of the slit 1 and the disk by detecting light passing through the slit 1, the slit row is composed of a plurality of slits bored at each constant central angle. , the plurality of slits are each set to a different slit width according to the absolute angle of the slit disk, and the angle detection sensor detects an amount of light according to the slit width of the slit, and adjusts the amount of light to the amount of light. The structure is configured such that the absolute angle of the slit disk can be detected based on the above-described structure, which has the advantage that the absolute angle of the rotating body can be reliably detected even in the presence of disturbances such as noise.

[Brief explanation of drawings]

Figures 1 to 4 show a rotary encoder as an embodiment of the present invention, where Figure 1 (a) is a front view, Figure 1 (b) is a side view, and Figure 2 is an angle detection diagram. FIG. 3 is a circuit diagram of the sensor, FIG. 3 is an output characteristic diagram of a light receiving element of the angle detection sensor, and FIGS. 4(a) and 4(b) are diagrams showing output signals of the angle detection sensor. 1... Slit disk, 4... Angle detection sensor,
2...1 slit row every l゜, 1 slit every 2a--1゜
・, 3-・Slit row every 10°, 3a...Slit row every 10°, 5, 6... Light emitting part (light source such as LED or light bulb), 7, 8... Light receiving part (photo 1)・1-light receiving element such as transistor or photodiode), R...resistance, 9
...A/D converter, 10--control unit.

Claims (1)

[Claims] A slit disk having an annular array of slits and attached to a rotating body, and an angle detection sensor that detects the absolute angle of the slit disk by detecting light passing through each slit in the slit array. In a rotary encoder, the slit row is made up of a plurality of slits drilled at fixed center angles, and each of the plurality of slits is set to have a different slit width depending on the absolute angle of the slit disk. and the angle detection sensor is configured to detect an amount of light corresponding to the slit width of the slit and detect the absolute angle of the slit disk based on the amount of light, Rotary encoder.