JPH0830660B2 - Rotary encoder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention has a disk having a plurality of slits extending in the radial direction arranged along the circumference, and sandwiching the disk. By arranging the light emitting element and the light receiving element at the facing position and rotating the disk, the light from the light emitting element is intermittently timed through the plurality of slits, and the intermittent light is received by the light receiving element, The present invention relates to a rotary encoder that generates a pulse signal according to the rotation speed of a disc.

[Prior Art] Conventionally, in this type of rotary encoder, a fixed slit in which a plurality of slits are arranged at the same angular intervals as the angular intervals of the slits facing the rotary disk having slits formed all around as described above. A plate is arranged so that only the light of the light from the light emitting element that passes through the slit of the rotating disk and further passes through the slit of the fixed slit plate is incident on the light receiving element. here,
When the angular interval of the slits of the rotating disk is N / 360 °, N pulses are taken out from the light receiving element per one rotation of the rotating disk.

The light receiving element generally has a light receiving surface capable of receiving light from several slits, and the amplitude of the output waveform from the light receiving element is determined according to the number of slits as the light receiving target.

In such a rotary encoder, the more the number of pulses generated per rotation, the more accurately the rotation number can be detected. Therefore, it is desired to increase the number of slits of the rotary disc as much as possible. There is. Among such discs, those of high pulse density are produced by etching a metal film deposited on a glass disc, but the production process is complicated and the product is expensive. On the other hand, the cheaper rotary discs are
Although it is formed by punching a metal plate, etching a metal plate, or plating, each has a limit in slit density in manufacturing, and even if a plating method suitable for forming high-density slits is used, the pitch of the slits is small. Since it is 150 μm or more, the number of slits is at most 7 / mm, and it is the current situation that higher density and hence higher pulse cannot be expected.

[Problem to be Solved] Therefore, an object of the present invention is to provide a rotary encoder capable of realizing a high pulse without increasing the number of slits.

[Means for Solving the Problem] In order to achieve such an object, the present invention provides a rotary disk having a slit row composed of slits arranged at equal intervals in the circumferential direction, and a rotary disk facing the rotary disk. Arranged, having a fixed slit plate having a slit row consisting of slits arranged at equal intervals in the circumferential direction, the light from the light emitting element is incident on the light receiving element through the rotating disk and the fixed slit plate, In a rotary encoder that takes out an output from a light receiving element, the array pitch of the slits of the rotating disk is N lines / circle, and the array pitch of the slits of the fixed slit plate is N × n / m (lines / circle) (however, m, n is a relatively prime integer, and m ≠ 1, n ≠ 1 and m
= N ± 1), a plurality of the slit rows are concentrically arranged on one of the rotary disk and the fixed slit plate, and the plurality of slit rows are offset from each other, and the light receiving element is 1 The slit width of each of the rotating disk and the fixed slit plate is smaller than the width of the light shielding portion between the slits.

Further, the present invention provides a rotating disk having a slit row composed of slits arranged at equal intervals in the circumferential direction, and a light receiving portion having a light receiving portion corresponding to the slit row composed of slits arranged at equal intervals in the circumferential direction. A rotary encoder having an element and a light source, wherein light from the light source is incident on the light receiving portion through the rotating disk and an output is taken out from the light receiving element, and an array pitch of slits of the rotating disk is N. / Circle, and the array pitch of the slits of the light receiving portion is N × n / m (lines / circle) (where m and n are relatively prime integers, m ≠ 1, n ≠ 1 and m
= N ± 1), a plurality of the slit rows are concentrically arranged on one of the rotating disk and the light receiving portion, and the plurality of slit rows are offset from each other, and one light receiving element is provided. The slit width of the rotary disc and the slit of the light receiving portion is smaller than the width of the light shielding portion between the slits.

[Operation] According to the present invention, the pitch of the slits of the rotating disk is made different from the pitch of the slits in the fixed slit plate or the slit pattern on the light receiving surface, and a plurality of slit rows are concentrically arranged. By making the slit width smaller than the slit light shielding width,
Since the number of pulses can be increased and the width of the pulses is also narrow, an output signal with less interference between pulses can be obtained. Further, even if the distance between the fixed slit or the slit of the light receiving element and the disc slit is large, the influence is small.

[Examples] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic view for explaining a rotary encoder of the present invention, in which 1 is a disc-shaped rotating disk,
Reference numeral 2 is a fan-shaped fixed slit plate, 3 is a light emitting element as a light source, and 4 is a light receiving element for receiving light from the light source 1 through the rotating disk 1 and the fixed slit plate 2. On the outer peripheral edge of the rotating disk 1, N slits 5 are formed in the circumferential direction at equal intervals of N pieces / circle. The fixed slit plate 2 has N × n / m lines / circumference in the circumferential direction of a circle forming a sector (where m and n are mutually prime integers, m ≠ 1, n ≠ 1 and m
= N ± 1) 1 to several slits 6 are formed at equal intervals. Here, the slits 5 and 6 are arranged at the same radial position when the rotary disk 1 and the fixed slit plate 2 are arranged to face each other.

Here, the relationship between the slits 5 and 6 is m = 3, n = 2, N =
The case of 500 will be described in detail with reference to FIG.

In FIG. 2, (A) and (C) show the relative positional relationship between the slit 6 of the fixed slit plate and the slit 5 of the rotating disk, and (B) shows the generation timing of the encoder output pulse P over time T. Shown with. In this case, the output pulse P occurs at every other one when viewed from the fixed slit plate side, and 2 × 500 = 1000 pulses are generated per one rotation. Here, when a pulse having a duty ratio of 1: 1 is obtained, if the slit width of each slit is 25 μm and the width of the light shielding portion of the disc is 75 μm, it corresponds to the pitch of one row of slits. The actual pitch is 50 μm.

In general, since the output pulse P is generated every n times, n × N pulses are generated per rotation,
Higher pulses can be achieved.

If m is set to a prime number other than n ± 1, the pitch of one slit, for example, the slit of the fixed slit plate becomes too wide, and the light receiving surface of the light receiving element cannot be made small. Therefore, the pitch of the slits is shortened by setting m = n ± 1.

FIG. 4 shows an embodiment of the present invention, in which the slits 13 and 14 are concentrically doubled in the rotary disk 1
Forming two slit rows. These two slit rows are, as shown in FIG. 5, slits indicated by a solid line and a broken line.
This is equivalent to a double-arranged slit array consisting of 15 and 16, whereby the slit pitch can be substantially shortened without shortening the slit pitch. The slit array is not limited to the double array, but can be generally arranged in an n-layer array.

In the present invention, the slit width is smaller than the width of the light shielding portion, but a resist pattern is formed on the metal thin plate, and a metal layer is formed by plating on the metal thin plate through the pattern,
Then, when the slit is formed by using the plating method for removing the metal thin plate and the resist pattern, the minimum value of the light shielding part is limited, but the width of the slit between the light shielding parts formed by the growth of the plating is narrowed. Easy to do. Therefore, the encoder of the present invention can be suitably manufactured by using such a plating method.

In this way, the pitch of the slits of the rotary disk and the pitch of the slits of the fixed slit plate are made different from each other, and the slit rows are concentrically arranged to reduce the slit spacing (pitch). The number of pulses can be increased without needing to do so, and the peaks of the light passing through these slits are narrow, so multiple pulses do not overlap each other, so multiple detection elements are provided and complex signal processing is performed. No need.

FIG. 3 shows another embodiment of the present invention. In this embodiment, a mask having a slit pattern corresponding to the slit 6 shown in FIG. 1 is closely arranged on the light receiving surface 12 of the light receiving element 11. To do. Alternatively, it is also possible to provide a light receiving device in which minute light receiving elements are integrally integrated and arranged in correspondence with the slit pattern. In this case, a separate fixed slit plate can be omitted.

Also, a good signal can be obtained even if the light receiving element is far from the rotating disk.

[Effects of the Invention] As is apparent from the above, according to the present invention, the pitch of the slits of the rotary disk and the pitch of the slits in the fixed slit plate or the slit pattern on the light-receiving surface are made different from each other, thereby substantially reducing It is possible to obtain a pulse output in which the number of pulses is increased, which corresponds to shortening the slit pitch.

Furthermore, in the present invention, the pitch of the slits of the rotating disk and the pitch of the slits in the fixed slit plate or the slit pattern on the light receiving surface are made different from each other, and any one of the slits is arranged concentrically in a multiplex manner. It is possible to obtain an encoder output with an increased number of pulses, which corresponds to a substantially shorter pitch of the slits, without narrowing the intervals of the slits.

The large number of pulses passing through these multiple slits
Since the slit width of the slit is smaller than the width of the light shielding part,
The output signals can be obtained as independent pulses without overlapping each other.

Therefore, a high-density pulse train can be obtained without performing special signal processing.

[Brief description of drawings]

FIG. 1 is a perspective view for explaining the present invention, FIG. 2 is an operation explanatory view thereof, FIG. 3 is a perspective view showing a light receiving element in another embodiment of the present invention, and FIG. 4 is an embodiment of the present invention. FIG. 5 is a plan view showing a rotating disk in an example, and FIG. 5 is an operation explanatory view thereof. 1 ... Rotating disc, 2 ... Rotating slit plate, 3 ... Light emitting element, 4 ... Light receiving element, 5 ... Slit, 6 ... Slit, 11 ... Light receiving element, 12 ... Light receiving surface with slit pattern , 13,14 …… Double array slit, 15,16 …… Slit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 54-36755 (JP, A) JP 60-21411 (JP, A) JP 52-63747 (JP, A) JP 58- 225318 (JP, A) Actually developed Sho-49-44262 (JP, U)

Claims (2)

[Claims] 1. A rotary disk having a slit row composed of slits arranged at equal intervals in the circumferential direction, and a slit row made of slits arranged so as to face the rotary disk and arranged at equal intervals in the circumferential direction. In a rotary encoder that has a fixed slit plate having, and makes light from a light emitting element incident on a light receiving element through the rotating disk and a fixed slit plate and takes out an output from the light receiving element, an array pitch of slits of the rotating disk. Is N / circle, and the array pitch of the slits of the fixed slit plate is N ×
n / m (book / lap) (where m and n are relatively prime integers,
m ≠ 1, n ≠ 1, and m = n ± 1), and a plurality of the slit rows are concentrically arranged on one of the rotary disk and the fixed slit plate, and the slit rows of the plurality of rows are arranged. The rotary encoder is characterized in that the number of the light receiving elements is one, and the slit width of the rotary disk and the slit of the fixed slit plate is smaller than the width of the light shielding portion between the slits. 2. A rotary disk having a slit row composed of slits arranged at equal intervals in the circumferential direction, and a light receiving element having a light receiving portion corresponding to the slit row composed of slits arranged at equal intervals in the circumferential direction. And a light source, wherein the light from the light source is incident on the light receiving portion via the rotating disk and the output is taken out from the light receiving element, the array pitch of slits of the rotating disk is N / And the array pitch of the slits of the light receiving portion is N × n / m (lines / circle) (where m and n are mutually prime integers, m ≠ 1, n ≠ 1 and m = n ± 1), a plurality of the slit rows are concentrically arranged on one of the rotary disk and the light receiving portion, and the plurality of slit rows are offset from each other, and the number of the light receiving elements is one and The rotary encoder characterized in that the slit width of the rotary disk and the slit of the light receiving portion is smaller than the width of the light shielding portion between the slits.