JPS63177019A - Position sensor - Google Patents

Abstract

PURPOSE:To achieve miniaturization and to enhance reliability by reducing the number of tracks, by applying all of or a part of the codes of an M-system to a predetermined number of items to the track of a recording medium at a predetermined pitch in order in the track direction. CONSTITUTION:The codes 44 of an M-system is recorded on the track of the peripheral end part of the circular recording medium 40 provided around a center shaft C in a freely rotatable manner in order to generate the original data relating to a position. A pickup 46 equipped with detectors 48-54 is provided in opposed relation to the track 42 in the track direction and the output data of the pickup 46 is converted to absolute position data by a data converting part 56. When the recording medium 40 is moved in an alpha-direction, the output codes by the detectors 48-54 change in the order of 1000 1100 1110 1111 0111 from 0000 corresponding to movement according to the M-system. The data converting part 56 converts the codes according to the M-system being the output of the pickup 46 and further converts the same to binary numbers showing '0' '1' '2' '3' '4' '5'... in order to output the same as absolute position data.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a position sensor, and in particular, a predetermined symbol representing an absolute position is attached to a recording medium, and a displacement sensor is detected relative to the recording medium. This relates to a rotary or linear type absolute position sensor that uses a pickup to read a code and output absolute position information.

<Prior art> An absolute type position sensor is, for example, shown in Fig. 19 (
As shown in A) and (B), a predetermined number of pits (the first
(3 bits in Figure 9), yl, number trunk 14~
16. 18 to 22 are provided and predetermined code information S L is provided for each.
”=s3'sl'~S.

′ is recorded, and the detectors 24-24 facing each track
28. Equipped with a pickup 36.38 having 30 to 34 so as to be movable relative to the recording medium in the track direction,
When the recording media 1o, 12 are rotated or linearly displaced relative to the pink-up 36, 38, each detector reads a track-shaped code and outputs it as absolute position information.

In Figure 19 (A) ro 11J, in (B) ``100
is being output.

In the magnetic type, a code is recorded by changing magnetization on a recording medium made of a magnetic material, and the code is read by a detector made of an MR element, etc.; in the optical type, the code is recorded by printing on a recording medium made of a transparent plate. A code is attached, and a detector such as a phototransistor is used to read the code based on changes in transmitted light or reflected light.

<Problems to be Solved by the Invention> Incidentally, in recent years there has been a strong demand for higher resolution, and 8-pit absolute position sensors have been produced. However, in order to obtain a high number of pits, a large number of tracks are required, and the linear type increases the size in the width direction, and the rotary type increases the size in the radial direction. At this time, when attempting to downsize the position sensor, the width of each track must be reduced, which deteriorates the S/N ratio and causes malfunctions. In addition, in the rotary type, the track diameters of the inner upper bit and the outer lower bit are different, so higher precision is always required for the code recording position in the circumferential direction for the upper bit than for the lower pit. For example, when changing from 011 to 100, there is a drawback that malfunctions are likely to occur due to poor synchronization between the falling edge of the lower bit and the rising edge of the upper bit.

The present invention was made in view of the drawbacks of the prior art,
It is an object of the present invention to provide a position sensor that can reduce the number of tracks, thereby reducing the size of the sensor and improving its reliability.

Means for Solving the Problems> FIG. 1 is a configuration diagram of a rotational absolute type position sensor according to an embodiment of the present invention. In the figure, 40 is the central axis C
42 is a recording medium 40 that is rotatable around the circular recording medium.
A track 44 is an M-series code recorded on the track 42 in order to generate original information related to the position, and 46 is a track arranged in a row in the track direction facing the track 42. 56 is a data conversion unit that converts the output information of the pickup 46 into absolute position information.

Effect> When the recording medium 40 and the pickup 46 are in the positional relationship shown in FIG. 1, the output code from each of the detectors 48 to 54 is 0000. When the recording medium 40 moves in the α direction,
According to the movement, the output code from each detector 48 to 54 is o.
After ooo 1000 → 1100 mountain pass 1110 → 1111
→0111→... and changes according to the M series.

The data converter 56 is the output of the pickup 46.
Convert the code according to the series, in order "0" → "1" → "
It is converted into a binary number representing "2" → "3" → "4" → "5" → . . . and output as absolute position data.

<Example> Next, a first example of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is an overall configuration diagram of a 4-pit rotary absolute type 1 position sensor, which is attached to a rotating shaft (not shown), is rotatable in both forward and reverse directions of α and β, and is attached to the circumferential edge of a circular transparent recording medium 40. One track 42 is provided in the circumferential direction, and this track 42 is 2'=16
Transparent in each divided area a to p (white area in Figure 1)
or “0”, which is distinguished by opacity (blacked out area in Figure 1).
”, the code 44 representing “1” is 1 in the M series as shown in the figure.
It is arranged by adding two O's. A pickup 46 is installed as a fixed side facing the track 42 of the recording medium 40, and the pickup 46 consists of phototransistors arranged along the track direction L at the same pitch as the areas a to p. Four detectors 48-54 are provided.

Each of the detectors 48 to 54 is connected to a pickup 46 of the recording medium 40.
Bits of "0" and "1" are output according to the presence or absence of transmitted light from the light source placed on the opposite side of the light source.

Therefore, the pickup 46 outputs a 4-bit code that is uniquely determined depending on the relative position with respect to the recording medium 40. A data converter 56 is connected to the output side of the pickup 46 via a parallel/serial converter 58 .

The data conversion unit 56 is composed of a microprocessor 60 that performs high-speed search calculation processing, and a memory 62 that stores a data conversion table that associates input codes and positions X as shown in FIG. Converts the input code to the corresponding position X and outputs it as absolute position data.

In FIG. 3, each time the recording medium 40 rotates by 22.5 degrees in the α direction, X increases by 1 in the range from θ to 15, and then α
When rotated in the direction, X returns to O, and conversely turns β by 22.5°
Each time it rotates in the direction, X decreases by 1 in the range of 15 to 0, and when it further rotates in the β direction, it returns to 15. .

Note that X may be expressed in binary code as 0000 to 1111, or as 0°, 22.5°,...337
．． It may also be expressed as an actual rotation angle that changes from 5° to 0°.

FIG. 4 shows an example of rearranging the data conversion table to speed up the search.

Also, the code of the M series including 0 added to the recording medium 40 is the seconds arranged in reverse order as 0000101001101111 with respect to a-p, for example, a part of the M series' series is 0 for a-j.
When the pickup 46 has relatively moved 6 steps from x=O and outputs 1011, an END mark code may be output instead of x=7. Furthermore, since there are two types of M sequences including 0 for 4 bits in addition to those shown in Figure 1, when using other W classes (1
One is 0000101111010011, the other lll!
0000110111100101), data conversion tables corresponding to each may be configured as shown in FIGS. 5 and 6.

Also, in addition to the M series in 4 bits, 2 pits,
M sequences corresponding to 3 bits, 5 bits, 6 bits, 8 bits, etc. may be attached to the recording medium 40, and the code may be read by a pickup having a number of detectors corresponding to the number of bits. Figures 7 to 11 show examples of data conversion tables for each pit when using an M series other than 4 pits, and the "O" or "1" at the right end viewed vertically is It forms a series (the first 0 is added).

Here, there is one type of M sequence for 2 pits, two types for 3 bits, and three types for 4 bits.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

Initially, when the recording medium 40 is in the state shown in FIG. 1 with respect to the pickup 46, the detection code of the pickup 46 by each of the detectors 48 to 54 is ooo.

After being converted into serial data by the parallel/serial converter 58, it is sent to the data converter 56, where it is converted into the corresponding position data x=O and output.

When the recording medium 40 moves in the α direction. First, after moving 22°5°, the detection code of the pickup 46 (Yo10
00, which is converted into serial data by the parallel/serial converter 58 and then input to the data converter 56, where it is converted to position data x-1 with reference to the table in FIG. 3 and output.

Next, after moving 45 degrees from the initial position, the detection hood of the pink-up 46 becomes 1100, and the data converter 56 outputs x==2. Similarly, recording medium 4
Every time 0 moves by 22.5 degrees, the detection code becomes 111.
It changes as o→1111→o111→..., and the position data also changes as x-3→x=4→X=5-... and is output.

When the recording medium 40 rotates 3600 times from the initial position and returns to its original position, the detection signal becomes oooo and X=0 is output again.

Note that when the recording medium 40 moves in the β direction, the angle is 22.5°.
The detection code changes from 0000 to 0001.
0010,... However, at this time, the output of the data converter 56 becomes X=O, X=15, x=14,... medium 4
Position data corresponding to the rotational position of 0 is obtained.

According to this embodiment, only one track is provided and four
It is possible to configure a bit absolute type rotational position sensor, which simplifies the code attached to the recording medium, making manufacturing easier.Also, even if the number of pits increases to 10, it is possible to configure Deterioration in position accuracy due to synchronization is eliminated, and it is possible to easily create a high-precision position sensor with the same dimensions as the conventional one. Since it is determined by the circumferential track T1, the outer circumferential track TIO
The diameter of the track 42 has inevitably become larger, and the shape of the sensor has also become larger. However, in this embodiment, the track 42 can be made with the conventional diameter of the innermost circumference (see Fig. 12 (B)).
It can be widely applied to devices that require high resolution and miniaturization.

Furthermore, even if the device is miniaturized, the number of tracks is one, so the track width can be widened and the S/N ratio can be improved.

FIG. 13 is a partially omitted perspective view showing a linear absolute and a mold position sensor according to a second embodiment of the present invention, and shows each area a' to band-shaped divided into a band-shaped transparent recording medium 70 on the fixed side. "0" differentiated by transparent or opaque in S',
As shown in the figure, the code 74 representing "1" is arranged by adding the first O and the last three OOO to the M series.

A pickup 76 is provided opposite the track 72 of the recording medium 70 so as to be movable in the α' or β' direction. Four detectors 78-84 are provided, consisting of phototransistors arranged at A.

Each of the detectors 78 to 84 is connected to a pickup 76 of the recording medium 70.
The semiconductor device outputs bits of "0" and "1" depending on the presence or absence of transmitted light from the light source.

The output side of the pickup 76 is connected to the data converter via the parallel/serial converter as in the embodiment shown in FIG. It is determined using a data conversion table similar to .

That is, when the pickup 76 is in the state shown in FIG. 13, the detection code of the pickup 76 is 0OOO,
The position data is x'20. When the pickup 76 moves in the α direction by one pitch in the areas a' to S', the detection code of the pickup 76 becomes 1000, and the position data becomes X.
'=1.

Similarly, each time the pickup 76 moves one pitch in the α direction, the detection code changes from 1100 to 1110 to 11.
11→0111→..., and the position data changes accordingly: x'=2→x'=3→x'=4→x';5...
And it changes.

Finally, when the pickup 76 comes to a position where the detector 78 faces the area S', the detection code of the pickup 76 becomes 0001, and at this time, the position data becomes χ'=15.

A linear position sensor of 5 bits or more can be similarly constructed.

According to the embodiment shown in FIG. 13, a 4-bit or multiple-bit linear absolute type position sensor can be constructed by simply providing one track, and a sufficient track width can be secured to accommodate the S.
Miniaturization can be easily achieved while maintaining a good /N ratio.

Next, FIG. 14 shows a recording medium 94 having a track 92 with a synchronization code 9α in addition to a track 42A with a 4-bit M sequence code 44A, and a recording medium 94 with a track 92 with a synchronization code 9α,
54A and a synchronization detector 96, the timing for detecting the code 44A is determined by each of the detectors 48A to 54A.

In a conventional position sensor including synchronous tracks, a plurality of tracks 98 to 10 for generating position information are used as shown in FIG.
A track 106 for generating a synchronization signal is provided on the outside of the sensor 11, and the synchronization code 108 attached to this track
By detecting the codes of tracks 98 to 104 with the detectors 112 to 118 at the timing when 0 is detected, it is possible to correct the synchrony between tracks, detect "0" for each track, and detect vertically continuous ro 000J. Or rl 111J was detected, but in view of the code arrangement error between tracks 98 to 104, the length of the synchronization code 108 in the track direction was short to ensure safety, so that the S/N ratio deteriorated. I was invited.

On the other hand, in FIG. 15, there is only one track for generating position information, so there is no need to consider synchronization between tracks, and the length of the synchronization code 90 in the track direction is set to 1. S/
It is possible to improve the N ratio.

FIG. 16 shows a differential rotary absolute position sensor according to a fourth embodiment of the present invention, which eliminates changes in detection characteristics due to temperature of the detector and improves output sensitivity. In this fourth embodiment, the recording medium 110
are provided with two tracks 112 and 114, and the track 112 contains a 4-bit M-sequence code 116 including the first O.
However, the track 114 is also marked with its inverted symbol 118, and four sets of tracks are placed at a predetermined pitch at positions facing each track 112 and 114, and the track 112 side and the 114 side form a pair. Detector 120.122, Detector 124.126, Detector 128.130, Detector 1
32.134 is equipped.

The output of each detector is led to a differential amplifier on the coarse side, and then judged as "0" or "1" by a comparator.

According to the fourth embodiment, the differential position sensor can also be configured extremely simply by providing only two tracks. On the other hand, in the past, a 4-bit differential type required 8 tracks, and a higher-order 16-bit differential type required 32 tracks, resulting in an extremely complicated configuration.

FIG. 17 shows a fifth embodiment of the present invention, in which one track 132 is provided on the surface of a drum-shaped recording medium 130 that is rotatable around an axis, and a predetermined number of bits (M series) are provided on this track 132. 1 in the track direction.
A pickup 134 is installed facing the outside of the pickup 132, and a plurality of detectors 136 are provided on the pickup 134 at a predetermined pitch in the track direction and facing the predetermined number of pits.
~150 are arranged.

According to the fifth embodiment, a drum-shaped position sensor having a predetermined resolution and accuracy can be formed thin. Conventionally, as shown in FIG. 18, since the number of tracks is required according to the number of bits, a drum 152 with a long axis is provided, and each track 154--
A pickup 154° with detectors 170 to 184 facing the drum 168 is disposed in the axial direction of the drum 152, resulting in a large pickup.

It should be noted that the microprocessor 60 and memory 62 shown in FIG. 1 have become less expensive due to recent advances in semiconductor technology, such as high-speed arithmetic microprocessors and large-capacity memories.

Further, in each of the above embodiments, an example is given of a configuration in which the M-series code is read optically, but the present invention is not limited to this in any way.
You may also read this.

<Effects of the Invention> As explained above, according to the position sensor according to the present invention, all or part of the M-series code for the n term is sequentially attached to the track of the recording medium at a predetermined pitch toward the trunk,
Since the code is read by a pickup including n-term detectors placed at a predetermined pitch opposite the truck and the data is converted to obtain position data, the sensor with a predetermined resolution can be It can be configured with a small number of tracks, making it easy to downsize, and also having a sufficient track width to improve the S/N ratio, as well as reducing malfunctions due to poor synchronization between tracks, improving reliability.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a rotary absolute type position sensor according to a first embodiment of the present invention, FIG. 2 is a plan view of a recording medium in FIG. 1, and FIG. 3 is an explanatory diagram of a data conversion table. Fig. 4 is an explanatory diagram showing a modification example equivalent to the data conversion table in Fig. 3, Figs. 5 and 6 are explanatory diagrams showing other data conversion tables, and Fig. 7 is an M sequence for 2 bits. An explanatory diagram showing a data conversion table when a code (adding the first 0; the same applies hereinafter) is attached to the trunk. Figures 8 (A) and (B) track two types of M-series codes for 3 pits. 9 to 11 are explanatory diagrams showing data conversion tables when M-sequence codes for 5 bits, 6 bits, and 8 bits are attached to tracks, respectively. , FIG. 12(A) is an explanatory diagram showing the size of the conventional rotary absolute-1 type recording medium, FIG. 12(B) is an explanatory diagram showing the size of the recording medium of the first embodiment, FIG. 13 is a partial configuration diagram of a linear absolute type position sensor according to a second embodiment of the present invention, FIG. 14 is a partial configuration diagram of a rotational absolute type position sensor according to a third embodiment of the present invention, and FIG. 15 is a partial configuration diagram of a rotary absolute type position sensor having a conventional synchronous track, No. 16
FIG. 17 is a partial configuration diagram of a rotary absolute type position sensor according to a fourth embodiment of the present invention, FIG. 17 is a partial configuration diagram of a drum type position sensor according to a fifth embodiment of the present invention, and FIG. 18 is a conventional Figure 19 (A) is a partial configuration diagram of a drum-type position sensor, Figure 19 (A) is a configuration diagram of a conventional rotary absolute type position sensor, and Figure 19 (B) is a configuration diagram of a conventional linear absolute type position sensor. . 40...recording medium, 42...track, 44...code,
46...Pickup, 48-54...Detector, 56...Data conversion unit Patent applicant Alpine Corporation Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 10 Fig. 11 Fig. 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 (B) 3s'

Claims (1)

[Claims] A code including all or a part of the M sequence for a predetermined number of terms is sequentially recorded at a predetermined pitch in the track direction on a track provided on a recording medium, and includes n detectors arranged opposite to the track. A position sensor characterized in that a pickup reads a code on a truck, and a data converter converts it into position data.