JPH0552590A - Detection element for absolute encoder - Google Patents

Abstract

PURPOSE:To enable application to other different pattern by selecting and adjusting a plurality of sensors which are arranged by less than one half pitch of the minimum read-out length of an one track type absolute pattern, into the predetermined interval of the number. CONSTITUTION:On an underside of a code plate A, an one track type absolute pattern P is formed, and, above the code plate A, a collimator lens L and a light source R are arranged. At a detection element B, a sensor array F on which sensors f1 to f20 are formed en bloc, and a selection circuit U which connects a plurality of sensors selectively from the sensors f1 to f20, to outputs u1 to u4, both are arranged on the same base plate by around one fourth pitch of less than one half of the minimum read-out unit length lambda of the pattern P. Each interval of the number of the sensors selected by the circuit U, can be changed selectively by a controller V. The controller V of the circuit U is previously set forth so as to connect the sensor f1 to the output u1, the sensor f5 to the output u2, the sensor f9 to the output u3, and the sensor f13 to the output u4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection element for an absolute encoder, in which a plurality of sensors for reading a pattern formed on a code plate are collectively formed on one substrate, and more specifically, The present invention relates to a technique in which the detection element can be shared even with another code plate having a one-track type absolute pattern having a different minimum reading unit length.

[0002]

2. Description of the Related Art An absolute encoder which outputs position information of a detecting portion with respect to a code plate as an absolute position signal peculiar to each relative position is basically composed of a code plate and a detecting portion which are relatively movable. The code plate is formed with an absolute pattern in which the numerals of the absolute position signal are replaced with specific physical information and arranged continuously.
A sensor for discriminating the physical information of the pattern is arranged in the detector. The absolute encoder is
It is roughly classified into a linear type in which the detector moves linearly along the strip-shaped code plate and a rotary type in which the detector moves angularly with respect to the disc or cylindrical code plate. In any case, it is a measuring instrument in which the scale information (absolute position signal) recorded as physical information on the absolute pattern is directly read by the sensor of the detection unit and reassembled into numbers.

Conventionally, as an absolute encoder, a plurality of incremental patterns each having a different pitch (multi-track type absolute pattern) are used.
Was read in parallel, and a multi-track type absolute encoder for assembling an absolute position signal having the number of digits corresponding to the number of tracks was general. However, in recent years, a one-track type has been actively researched and put into practical use instead of the multi-track type. The 1-track type absolute encoder is
The absolute pattern is composed of one irregular pattern called a one-track type absolute pattern, and the number of patterns is small, so that the multi-track type absolute pattern is used. -Compared to the encoder, the machine configuration is simple, which is advantageous for downsizing the entire machine and automating assembly.

The 1-track type absolute pattern is one column in which 1 and 0 of a special binary number sequence such as a full-cycle sequence or an M sequence are replaced with two kinds of minimum reading units (for example, transparent and opaque). When a binary number (absolute position signal) is assembled by independently reading a predetermined plurality of minimum reading units that are adjacent to each other on the pattern, The absolute positions of the minimum number of reading units can be discriminated from each other. Although this absolute position signal is merely a "binary number which is different from each other but whose order is completely random", it can be converted into an easy-to-handle absolute position signal such as a binary code by using recent semiconductor memory devices which can be obtained at low cost. It can be converted to one-to-one.

On the other hand, in order to read the 1-track type absolute pattern, the detection section is provided with a plurality of sensors at a pitch of the minimum reading unit length of the 1-track type absolute pattern. Arranged along the lane, each sensor reads one bit of each digit that constitutes an absolute position signal. Therefore, if it is attempted to achieve high resolution of the absolute encoder by shortening the minimum reading unit length, the sensor pitch and aperture are reduced and the variation of the output characteristics of the sensor is increased, resulting in a read SN ratio. There is also the problem of lowering. However, regarding these sensors, it is possible to use an integrated circuit type detection element in which a plurality of sensors having uniform characteristics and shapes are collectively formed on one substrate by applying semiconductor manufacturing technology that has made remarkable progress in recent years. it can.

Most of the practical one-track type absolute encoders have an incremental pattern arranged on the code plate side by side with the one-track type absolute pattern. Incremental pattern
It is a repeating pattern of 0 and 1 at equal intervals, and normally, the minimum reading unit length of the one-track type absolute pattern is λ, and n is a natural number, the pitch λ or the pitch λ.
/ 2 ⁿ is adopted, and both may be adopted to use two or more in total. The application of these incremental patterns is to control the reading position (time) of the 1-track type absolute pattern so that the reading can be performed while avoiding the boundary area of the minimum reading unit. The absolute position signal is divided into smaller parts and assembled into finer increments. The 1-track absolute pattern detection signals are aligned with the rising edges to improve the position accuracy of the absolute position signal. To be done.

As a one-track type absolute encoder using an incremental pattern for the above-mentioned purpose, the applicant of the present application has previously mentioned that the "absolute encoder" of Japanese Patent Application No. 3-103723. Was proposed. Here, for one-track type absolute pattern reading, two sets of sensor groups having a pitch λ equal to the minimum reading unit length are provided with a phase difference of 1 / 2λ, and the pitch obtained from the incremental pattern is set. The two sensor groups are alternately switched according to 1, 0 of the square wave of λ. Therefore, the 1-track type absolute pattern reading sensor is apparently arranged in the detecting portion at a pitch of 1 / 2λ.

An optical one-track type absolute-type absolute-type absolute-type absolute-type absolute-type absolute-type absolute-type absolute-type linear-type absolute
As an example of the encoder, the applicant of the present application has previously filed Japanese Patent Application No. 2
Proposed "Absolute Encoder" of No. 187988. Here, two incremental patterns are arranged on the code plate, and the pitch of one of the incremental patterns is ⅛ of the minimum reading unit length of the one-track type absolute pattern. It is stipulated in. As shown in this prior application, for the optical detection of the incremental pattern, a mask (index scale), which is a part of the incremental pattern, is fixed on the sensor, and the pattern is fixed. It is possible to employ a method of detecting the overlap between the index scale and the index scale. According to this method, it is possible to obtain a detection signal having a high SN ratio, which is obtained by combining a plurality of pitches of the incremental pattern. Therefore, in order to improve the resolution of the absolute encoder, the method of dividing the minimum reading unit length using the incremental pattern is extremely effective.

Further, as an example of the optical detecting means for the one-track type absolute pattern and the incremental pattern, the applicant of the present application has previously filed Japanese Patent Application No.
No. 406194, "Optical Absolute Enco-
Da ”was proposed. Here, all the sensors for both patterns are arranged in a common detection element (on the substrate), and the light source for reading is also shared.

According to these prior applications, the absolute
The encoder can be downsized and the resolution can be increased without reducing the minimum reading unit length of the 1-track type absolute pattern. Incremental pattern can be used on the contrary. The minimum reading unit number (pulse number) of the type absolute pattern is significantly reduced, and the minimum reading unit length can be significantly increased.

[0011]

By the way, even if it is a rudimentary absolute encoder that simply reads only the one-track type absolute pattern, it will be called a one-track type absolute pattern. Multiple incremental
Even if it is an advanced 1-track type absolute encoder that reads patterns in parallel, the minimum reading unit length is different 1.
There is a problem that the detection element cannot be shared with the code plate provided with the track-type absolute pattern. 1
The sensors for track type absolute pattern detection are special parts arranged at a pitch equal to the minimum reading unit length and adapted only to the pattern of the minimum reading unit length. It cannot be diverted to a one-track type absolute pattern with a reading unit length. This impedes common use of parts when designing and manufacturing an absolute encoder depending on the application, and may lead to an increase in product price.

For example, the minimum number of reading units per one track type absolute pattern is 100 (100 pulses).
When the detector element of the rotary type absolute encoder described above is to be shared with the rotary type absolute encoder of 60 pulses, the minimum reading unit length is maintained as it is. The diameter of the one-track type absolute pattern will be reduced. At this time, the mounting positions of the detection element and the light source are also moved to the inside of the code plate, and it is necessary to remake the entire housing in accordance with these new arrangements. On the contrary, if the mounting position of the detection element or the light source is left unchanged and the entire housing is shared, the minimum reading unit length is increased, and
It is also necessary to increase the pitch of the track type absolute pattern detection sensor.

In the case of a detecting element adapted to read both the 1-track type absolute pattern and the incremental pattern, the minimum reading unit length of the 1-track type absolute pattern is changed. This is further troublesome because it involves changing the pitch of the incremental pattern and adjusting the positions of the sensors relative to each other. In the case of an absolute encoder that uses an index scale to detect an incremental pattern, the index scale is applied to an incremental pattern with a different pitch.
Since the same scale cannot be shared, the index scale is recreated according to the new minimum reading unit length, and this index scale is positioned so as to match the detection signal of the new 1-track absolute pattern. Need to be adjusted.

That is, the code plate pattern is remade
For example, in the case of the optical type, it is extremely easy to peel off the existing pattern, form a metal thin film, and form a new pattern, and in the case of the magnetic type, it is extremely easy to just magnetize. Reuse) is almost impossible, and each must be newly designed and manufactured. Therefore, the inflexibility of the detecting element for the change of the minimum reading unit length is a major time and cost obstacle to the change of the specifications of the one-track type absolute encoder.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a detection element for an absolute encoder, which has high flexibility for changing the minimum reading unit length. ..

[0016]

An absolute solution according to claim 1
The detecting element for the encoder / encoder is the same as the detecting element for the absolute encoder which reads a 1-track type absolute pattern.
A plurality of sensors arranged at a pitch less than 1/2 of the minimum reading unit length of the pattern, and a selection means for selecting the plurality of sensors at a predetermined number of intervals, and adjusting the number of intervals. Thus, it is possible to correspond to another one-track type absolute pattern having a different minimum reading unit length.

According to a second aspect of the present invention, there is provided a detecting element for an absolute encoder, which reads a 1-track type absolute pattern and an incremental pattern in parallel and reads the incremental pattern. In a detection element for an absolute encoder, which is performed by detecting the overlap between the incremental pattern and the index scale, 1 / of the minimum reading unit length of the absolute pattern A plurality of sensors arranged at a pitch of less than 2 and the incremental pattern and index
A substrate provided side by side with a detection sensor for detecting the overlap with the scale, and a transparent protective plate which is provided on the substrate and is replaceable and on which an index scale is partially formed,
Is to have.

[0018]

In the detecting element for the absolute encoder according to claim 1, among the plurality of sensors, a plurality of sensors are selected at a number interval set in the selecting means.
A track type absolute pattern is read. This number interval is set so that at least one sensor is selected for each substantially minimum reading unit length of the one-track type absolute pattern. Here, it is assumed that each minimum reading unit length is set so that even if the ratio between the sensor pitch and the minimum reading unit length is not an integer or a simple fraction, each number interval can be adjusted individually for expansion and contraction. Show what you can do. Further, the term "at least one sensor" means that the sensor for each of the minimum reading unit lengths and some sensors before and after that can be collectively handled as one sensor.

For example, when reading eight minimum reading units of a certain one track type absolute pattern using 30 sensors arranged at three pitches per minimum reading unit length λ, 30 One of every three sensors is selected to set a total of eight. However, one output is added to each of the eight outputs so as to add one output to each of the eight outputs.
Six may be set, or 24 may be set by adding two outputs before and after each. As a result, the substantial output is increased and the read S / N ratio can be improved.

When another one-track type absolute pattern having a minimum read unit length of 8 / 7λ is read by the eight minimum read units by using the detection element having the thirty sensors, the minimum read unit is used. Since the unit length is long by ⅛λ, some of the set intervals of the eight sensors are set every four. That is, 1 to 30 sensors
When set to 0, for example, 2, 5, 9, 12, 16, 1
The numbers 9, 23, and 26 may be set. At this time, in the positional relationship between the code plate and the detection element where one sensor detects the center of the minimum reading unit, the other sensor detects a position deviated from the center of the minimum reading unit. By limiting the timing of reading (phase position), the reading error can be avoided.

On the other hand, the sensor pitch is further reduced,
Alternatively, by increasing the number of sensors per minimum reading unit length by increasing the minimum reading unit length by reducing the minimum reading unit number (pulse number) of the 1-track type absolute pattern, The number interval of selection can be adjusted appropriately. In this case, when the sensor pitch of is reduced, a measure is taken to secure the SN ratio of reading, and when the number of pulses of the 1-track type absolute pattern is reduced, the resolution of the code plate is secured. It is necessary to take measures.

According to a second aspect of the present invention, there is provided a detecting element for an absolute encoder, which is arranged in an optical one-track type absolute pattern and has one or more optical incremental sensors.
Absolute encoder with pattern on code plate
Applied to Da. 1-track type absolute pattern
With respect to the cable, even in the same manner as in the first aspect, it is possible to correspond to another one-track type absolute pattern having a different minimum reading unit length. On the other hand, the incremental pattern is read by detecting the transmitted light when the pattern and the index scale overlap each other, so that the original transparent protective plate is different from the one with the pitch of the index scale being different. It can be replaced with a transparent protection plate to support incremental patterns of different pitches.

The phase adjustment of the incremental pattern detection signal with respect to the 1-track type absolute pattern detection signal within one pitch can be performed by adjusting the position of the index scale with respect to the substrate on which the sensor is arranged. it can. Therefore, if you add a structure that allows you to position the protective plate with high precision without adjustment and prepare several types of transparent protective plates with different precision pitches and scales, you can increase the incremental cost. It is more convenient because the phase adjustment within one pitch of the pattern detection signal can be omitted.

As described in the prior art, according to the method of finely dividing the minimum reading unit length of the one-track type absolute pattern using the incremental pattern, the one-track type absolute pattern is used. Even if the minimum reading unit length of the print pattern is significantly increased, the insufficient resolution can be sufficiently compensated by the method. The expansion of the minimum reading unit length achieved in this way is the expansion of the opening of the 1-track type absolute pattern detection sensor,
It is possible to simultaneously increase the distance from the 1-track type absolute pattern to the sensor. On the other hand, in the case of the incremental pattern, the distance from the sensor for detecting the transmitted light of the overlap between the pattern and the index scale may be wide as long as the distance between the pattern and the index scale is small.

Therefore, if such a design procedure is adopted, the resolution and reading of the absolute encoder can be achieved even if the transparent protective plate is replaceably arranged between the substrate on which the sensor is arranged and the code plate. The signal-to-noise ratio of is not affected at all. On the other hand, the transparent protective plate, of course, protects the sensor on the substrate and increases the resistance of the absolute encoder to moisture in the environment, dust in the housing, direct rubbing against the code plate, and the like. To improve the durability and reliability of the encoder.

[0026]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram for explaining the detection element for absolute encoder of the first embodiment. Here, an integrated circuit (sensor array) type detection element reads an optical one-track type absolute pattern under the illumination of parallel light.

In FIG. 1, a one-track type absolute pattern P is formed on the lower surface of the code plate A, and a collimating lens L and a light source R are arranged above the code plate A. There is. The detection element B has sensors f1 to f2 on the same substrate at a pitch (1 / 4λ) of about 1/4 of the minimum reading unit length λ of the one-track type absolute pattern P.
Sensor array F in which 0s are collectively formed and sensors f1 to f2
Select a plurality of sensors from 0 and output u1 to u4
And a selection circuit U connected to. The number interval of the respective sensors selected by the selection circuit U can be continuously changed by the adjuster V. Here, the regulator V of the selection circuit U
In advance, the sensor f1 is connected to the output u1, the sensor f5 is connected to the output f2, the sensor f9 is connected to the output f3, and the sensor f13 is connected to the output f4.

In the detecting element for the absolute encoder having the above structure, the light source R and the collimator are used.
The parallel light generated by the lens L forms a shadow of the one-track type absolute pattern P on the sensor array F, and the density of the shadow is reflected in the output of each of the sensors f1 to f20. The selection circuit U outputs the outputs of the four selected sensors f1, f5, f9, and f12 to the terminal u, respectively.
Output to 1, u2, u3, u4.

When the detecting element for the absolute encoder is made to correspond to another one-track type absolute pattern having a different minimum reading unit length, the adjuster V of the selection circuit U is readjusted. The new minimum reading unit length. In this way, the light source R, the collimating lens L, the sensor array F, and the selection circuit W can be shared.

In the selection circuit U of FIG. 1, 2 per minimum reading unit length λ of the one-track type absolute pattern.
Select each sensor, divide these sensors into two groups, and switch between both groups alternately to read the 1-track type absolute pattern while avoiding the boundary area of the minimum reading unit. You can also do so. Similar to the example in Japanese Patent Application No. 3-103723 of the prior application, at this time,
On the code plate A, an incremental pattern with a pitch λ is arranged side by side with a one-track type absolute pattern P, and according to 1, 0 of a square wave with a pitch λ obtained from the incremental pattern. The two sets of sensors are switched alternately.

FIG. 2 is a schematic view of the detecting element for the absolute encoder of the second embodiment, FIG. 3 is a plan view of an integrated circuit of the detecting element of FIG. 2, and FIG. 4 is a light shielding of the detecting element of FIG. FIG. 5 is a plan view of the plate, and FIG. 5 is a partial plan view of the code plate of FIG. Figure 2
The 1-track absolute pattern and the incremental pattern are read in the direction perpendicular to the drawing.

In FIG. 2, a one-track type absolute pattern P and two incremental patterns I and J are arranged on the lower surface of the code plate A, and above the code plate A, A collimating lens L and a light source R are arranged. The detection element B mounted on the printed circuit board K has a semiconductor substrate D, a transparent protective plate H, and a case for positioning them.
(Not shown). On the semiconductor substrate D, a plurality of sensors F arranged at a pitch of about 1/8 of the minimum reading unit length of the one-track type absolute pattern P.
And a sensor G for detecting the incremental pattern I
And the sensor E for detecting the incremental pattern J are collectively formed. Further, a light shielding film S is formed on the surface of the transparent protective plate H, and by pattern etching of the light shielding film S, a rectangular transparent portion C is provided at a position corresponding to the sensor F and a position corresponding to the sensors G and E. Index scales N and M are formed in each of them.

3 to 5, the one-track type absolute pattern P formed on the lower surface of the code plate A of FIG. 5 is actually composed of a pair of reversal patterns P1 and P2. .. By obtaining the output difference between the corresponding sensors of the sensors F1 and F2 of FIG. 3 provided for the pair of inversion patterns P1 and P2, the substantial output value of each sensor is doubled, and Even if the frontage of the sensor is so narrow, it is possible to secure a sufficient SN ratio for reading. Therefore, the transparent portion C of the transparent protective plate H of FIG.
Two C1 and C2 are prepared corresponding to the sensors F1 and F2 of FIG.

In FIG. 5, an incremental pattern is shown.
I is a 1-track type absolute pattern P1, P
Pitch equal to the minimum reading unit length of 2, while the incremental pattern J is a 1-track absolute
The patterns P1 and P2 are formed at a pitch of 1/4 of the minimum reading unit length. In contrast to the incremental pattern I shown in FIG. 5, four sensors G1, G2, G3 and G4 are arranged on the semiconductor substrate D shown in FIG. Similarly, for the incremental pattern J, four sensors E1, E2, E3, E4 are arranged. These sensors F1, F2, G1, G2, G3, G4, E1, E2,
The outputs of E3 and E4 are output to the outside of the semiconductor substrate D through the terminal Q.

The light-shielding film S of the transparent protective plate H shown in FIG. 4 corresponds to the four sensors G1, G2, G3 and G4 and has an index scale for the incremental pattern I.
Le N1, N2, N3, N4, and also four sensors E
Index scales M1 and M for incremental pattern J corresponding to 1, E2, E3 and E4
2, M3 and M4 are formed in patterns. The relationship between the index scales N1 and N2 and the index scales N3 and N4, and the index scales M1 and M2.
The relationship between 3 and M4 is the incremental pattern.
It is shifted by 1/4 pitch of the I and J, A phase,
This is for obtaining the output of the B phase.

A code plate having another one-track type absolute pattern having a different minimum reading unit length from the detection element for the absolute encoder (as a matter of course, the pitch of the incremental pattern is also different). If the transparent protective plate H is replaced, the detecting element for the absolute encoder can be used as it is. That is, the index scales N1, N2, N of FIG.
The pitches of 3 and N4 have been changed to those of the minimum reading unit length of the new 1-track type absolute pattern, and the pitches of the index scales M1, M2, M3 and M4 have been changed to the new 1-track type absolute pattern.・ Revise the pattern to be 1/4 of the minimum reading unit length.

In the absolute encoder detecting element of the second embodiment having the above-mentioned structure, the light from the light source R is collimated by the collimator lens L, and the collimated light is applied to the code plate A. The parallel light that has passed through the respective patterns is converted into one-track type absolute patterns P1 and P2.
In the case of, the 1-track type absolute pattern P1 and P2 as the light-dark pattern is formed on the sensors F1 and F2 of FIG. 3 through the transparent portions C1 and C2 of the transparent protective plate H of FIG. .. This pattern is read by F1 and F2. On the other hand, the light passing through the incremental patterns I and J in FIG. 5 is the index scale of the transparent protective plate H having the pattern in FIG.
Irradiation with N1, N2, N3, N4, M1, M2, M3 and M4. The intensity of the light after passing through the sensor G1 in FIG.
An incremental signal is obtained by detecting by G2, G3, G4, E1, E2, E3, E4.

The absolute position is first detected by the sensor E of FIG.
The outputs of the square waves obtained from the sensors G1, G2, G3, and G4 synchronized with the square waves obtained from 1, E2, E3, and E4 are combined to form an auxiliary signal that divides the minimum read unit length into four. .. 1/4 of the minimum reading unit length using this auxiliary signal
The absolute positional relationship between the code plate A and the detecting element B is determined to be 1/4 of the minimum reading unit length.
1 track type absolute patterns P1 and P from the sensors F1 and F2 respectively depending on which absolute position
The leading sensor number for detecting 2 is determined. at the same time,
Four sensors are selected from the sensors F1 and F2 for each number interval corresponding to the minimum reading unit length with the head sensor number as the head, and the 1-track type absolute pattern P1 and P2 are read. .. As a result, 16 absolute positions along the 1-track type absolute patterns P1 and P2 are discriminated. By combining these 16 absolute position signals with the previous auxiliary absolute position signal, 1
The 64 absolute positions along the track type absolute patterns P1 and P2 are discriminated from each other.

When the number of pulses of the code plate A in FIG. 5 is changed, it is conventional that the sensors F1 and F2 shown in FIG. 3 are used.
You have to change the pitch of. In the case of this embodiment,
If the minimum reading unit length is a one-track type absolute pattern having a pitch up to twice the pitch of the sensors F1 and F2 and an incremental pattern corresponding to this, at least the semiconductor substrate D of the detection element B is It can be diverted without any change. The index scales N1, N2, N3, N4, M1, M of the transparent protective plate H shown in FIG. 4 are changed.
Only the pitch of 2, M3, M4,
Scale N1, N2, N3, N4, M1, M2, M3,
The pitch of M4 is only changed according to the minimum reading unit length (or the number of pulses) of the new code plate.

In the case of this embodiment, the detection element B is connected to the sensor F.
If the outputs of all the sensors of 1 and F2 are taken out respectively, an enormous number of terminals are required. Therefore, a shift register analog switch for serially transferring the sensors F1 and F2 by an external clock is incorporated. ..

[0042]

According to the detecting element for the absolute encoder of the first aspect of the present invention, a plurality of one tracks having different minimum reading unit lengths can be obtained only by resetting the number interval set in the selecting means. One type of detecting element can be commonly used for the type absolute pattern. As a result, in the case of the detection element, the housing, and the optical type, the light source is shared as it is, and various types of absolute encoders (for example, 1
It is possible to design and manufacture a rotary type absolute encoder) having a different number of pulses on the circumference. This makes it possible to use a wide variety of absolute encoders depending on the application.
We can provide da at low cost with short delivery time.

In the detecting element for an absolute encoder according to claim 2, a plurality of one-track type absolute detecting elements having different minimum reading unit lengths can be obtained only by replacing or remaking the transparent protective plate of the detecting element. For a plurality of incremental patterns with different patterns and different pitches, the main part (substrate, wiring,
Can be commonly used. As a result, the commonization of components is promoted, and a wide variety of absolute encoders can be provided at low cost with a short delivery time according to the application. In addition, the sensor is protected by a transparent protective plate, which increases resistance to environmental changes such as humidity, dust intrusion, contact between the code plate and the detection element during assembly, and the reliability of the absolute encoder. Is improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a detection element for an absolute encoder according to a first embodiment.

FIG. 2 is a schematic diagram of a detection element for an absolute encoder according to a second embodiment.

3 is a plan view of a semiconductor substrate of the detection element of FIG.

FIG. 4 is a plan view of a protective plate of the detection element of FIG.

5 is a partial plan view of the code plate of FIG. 2. FIG.

[Explanation of symbols]

 A code plate B detection element C transparent part D semiconductor substrate E sensor F sensor G sensor H transparent protective plate I incremental pattern J incremental pattern K printed circuit board L collimator lens M index scale N index Scale P 1-track type absolute pattern R Light emitting diode S Light-shielding film

Claims (2)

[Claims] 1. A detection element for an absolute encoder for reading a one-track type absolute pattern, wherein the minimum reading unit length of the one-track type absolute pattern is 1/2. A plurality of sensors arranged at a pitch of less than 1 and a selection means for selecting the plurality of sensors at a predetermined number of intervals. By adjusting the number of intervals, another track having a different minimum reading unit length is provided. Type absolute
A detector element for an absolute encoder, which is characterized in that it can also be applied to a touch pattern. 2. A one-track type absolute pattern and an incremental pattern are read in parallel, and the reading of the incremental pattern is performed by the incremental pattern and the index scale. In an absolute encoder detection element for detecting overlap, a plurality of sensors arranged at a pitch less than 1/2 of the minimum reading unit length of the absolute pattern and the incremental sensor. .Transparent with a substrate provided side by side with a detection sensor for detecting the overlap between the pattern and the index scale, and replaceably provided on the substrate, with the index scale partially formed A detection element for an absolute encoder, which has a protective plate.