JP2007333401A - Optical encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical encoder capable of providing an excellent encoder signal by ensuring the degree of attachment freedom between a sensor head and a scale. <P>SOLUTION: The optical encoder includes: one or more light sources 103; a sensor head 101 having one or more light detectors 104; the scale 120 relatively displacing with respect to the sensor head 101; and an abutting member 106 keeping the sensor head 101 and the scale 120 in a desired arrangement relationship. Light emitted from the light source 103 is reflected or diffracted by the scale 120; the reflected or diffracted light is received by the light detector 104 to output a displacement signal from the sensor heat 101; and a surface of the sensor head 101 facing to the scale 120 is used as an abutted surface 105 abutted on the abutting member 106. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical encoder that detects the position and the like of an object to be detected.

  There is known an optical encoder that includes a scale having a light source, a grating pattern that reflects or diffracts light emitted from the light source, and a photodetector that receives light reflected or diffracted by the scale. This type of optical encoder is often used as a device for detecting movement information of a detected object, for example, a movement amount, a movement direction, and the like.

  Here, in an optical encoder, for example, a configuration disclosed in Patent Document 1 is known as a representative example in which an encoder head in which a light source and a light detector are housed in one package is mounted on an abutting member.

  (A), (b), and (c) of FIG. 11 each show a cross-sectional configuration of a conventional optical encoder. In FIG. 11, the soldering lead 92 provided on a part of the head 91 on the base substrate 97 is mounted so as to be in direct contact with the copper foil pattern 95 provided on the abutting member.

JP-A-9-126815

  (A), (b), and (c) of FIG. 12 are diagrams for explaining an encoder signal. In the optical encoder, for example, a displacement signal is obtained from the sensor head 1 by the relative movement of the scale 2 having a reflective / non-reflective grating pattern with a pitch P relative to the sensor head 1.

  Here, the displacement signal is a two-phase (A phase, B phase) analog signal whose phase that periodically changes according to the relative movement between the scale 2 and the sensor head 1 is shifted by 90 degrees, or this analog signal. Is a digital signal converted by a signal processing circuit.

  Here, a good displacement signal can be obtained if the positional relationship between the light source, each member including the photodetector and the scale 2 arranged in the sensor head 1 is accurately arranged at a desired position. The higher the resolution, the higher the placement accuracy is required.

  In general, after the light source and the photodetector are housed in one package, the sensor head 1 is mounted on the base substrate while adjusting the arrangement of the sensor head 1 and the scale 2 so as to obtain a good displacement signal. . For this reason, it is preferable that it is a structure with which attachment adjustments, such as an attitude | position and arrangement | positioning when mounting the sensor head 1 to a base substrate, are easy.

  As shown in FIGS. 13A, 13B, and 13C, the direction of the degree of freedom for mounting the sensor head 1 and the scale 2 is the horizontal direction (X, Y) between the sensor head 1 and the scale 2, The interval direction (Z) and the rotation direction (θy, θr, θp) are conceivable. And it is preferable that adjustment in each of these directions is possible.

  The present invention has been made in view of the above, and an object thereof is to provide an optical encoder capable of obtaining a good encoder signal by securing a degree of freedom in mounting between a sensor head and a scale. .

  In order to solve the above-described problems and achieve the object, according to the present invention, a sensor head having a light source, a photodetector, a scale that is displaced relative to the sensor head, a sensor head, and a scale are provided. An abutting member that holds the desired arrangement relationship, and reflects or diffracts light emitted from the light source with a scale, receives the reflected or diffracted light with a photodetector, and outputs a displacement signal from the sensor head. It is possible to provide an optical encoder characterized in that the surface facing the scale of the sensor head is an abutting surface that abuts against the abutting member.

  Further, according to a preferred aspect of the present invention, the external lead wiring further includes a substrate electrically connected to the sensor head, and is electrically connected to the substrate on a surface other than the abutting surface of the sensor head. It is desirable that an electrode be formed.

  Moreover, according to the preferable aspect of this invention, it is desirable for the abutting surface side of the sensor head of an abutting member to have a level | step difference shape.

  According to a preferred aspect of the present invention, the abutting member includes a transmission region that transmits light of a path that is emitted from the light source, reflected or diffracted by the scale, and incident on the photodetector, and at least one of the periphery of the transmission region. It is desirable to have the light shielding structure formed in the part or the whole area.

  Further, according to a preferred aspect of the present invention, the abutting member includes at least a part between the abutting surface of the sensor head and the abutting member, and a distance and an inclination between the abutting surface of the sensor head and the scale. It is desirable to have an adjustment unit that adjusts at least one of them.

  Moreover, according to the preferable aspect of this invention, it is desirable to arrange | position the abutting surface of a sensor head incline with respect to the scale pattern surface of a scale using an adjustment part.

  Moreover, according to the preferable aspect of this invention, it is desirable that an adjustment part is a thin plate.

  Further, according to a preferred aspect of the present invention, it is desirable that at least one side surface excluding the abutting surface of the sensor head is a butting surface when mounted on the abutting member.

  Moreover, according to the preferable aspect of this invention, it is desirable for the abutting surface of a sensor head to be resin.

  According to the present invention, there is an effect that it is possible to provide an optical encoder capable of obtaining a good encoder signal by securing a degree of freedom of attachment between the sensor head and the scale.

  Embodiments of an optical encoder according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  FIG. 1 is a side view showing a cross-sectional configuration of the optical encoder according to the first embodiment of the present invention. FIG. 2 is a perspective view thereof. An optical encoder 100 shown in FIG. 1 includes a sensor head 101 having a light source 103 and a photodetector 104 therein, and a scale 120 having a lattice pattern 121 that moves linearly relative to the sensor head 101. . The optical encoder 100 is a reflective optical encoder.

  Here, the sensor head 101 includes a light source 103 such as an LED or a semiconductor laser and a light source 103 disposed so as to emit light mainly in the direction of the scale 120 on a wiring substrate 109 made of ceramic or resin on which electrodes are formed. A photodetector 104 for detecting the light emitted and reflected or diffracted by the scale 120 is mounted.

  The wiring board 109 including the light source 103 and the photodetector 104 is entirely covered with a light transmissive material 110 such as a transparent resin. Thereby, the abutting surface 105 described later is made of resin. By adopting a resin-sealed configuration covered with resin in this way, the sensor head can be manufactured at low cost.

  Further, the light source 103 and the photodetector 104 are electrically connected to a wiring electrode formed on the wiring substrate 109, and at least a part of the light source 103 and the photodetector 104 can be electrically connected to the outside by an external extraction electrode 107. .

  Further, the external extraction electrode 107 is electrically connected to the wiring 131 formed on the external wiring substrate 130 via the conductive material 108. Further, the sensor head 101 is configured to abut against the abutting member 106 disposed in a desired positional relationship between the scale 120 and the sensor head 101 and fixed and held with an adhesive or the like.

  Here, the abutting surface 105 of the sensor head 101 with the abutting member 106 is a surface facing the scale 120. The abutting surface 105 is a light incident / exit surface on which the outgoing light Lout emitted from the light source 103 and emitted toward the scale and the incident light Lin reflected or diffracted by the scale 120 and incident on the photodetector 104 are incident. It is.

  Next, an example of how to obtain the arrangement relationship of each member will be briefly described. First, the arrangement relationship of the light source 103, the photodetector 104, and the scale 120 is obtained from the theoretical relationship between the Lout length and the Lin length that provides a good encoder signal (displacement signal).

  Then, the thickness of the light transmissive material 110 and the distance between the abutting surface 105 of the sensor head 101 and the scale 120 are obtained in consideration of the refractive index of the light transmissive material 110. Then, the position of the abutting member 106 is determined.

  For example, if Lin = Lout = Z (Z: a desired value), the light source 103 and the photodetector are arranged on the wiring board 109 so that the light emitting surface of the light source 103 and the light receiving surface of the photodetector 104 are aligned. 104 is arranged. Further, the position of the abutting member 106 is determined so that the abutting surface 105 of the sensor head 101 and the lattice pattern 121 surface of the scale 120 are substantially parallel.

  Next, an example of a mounting method of the sensor head 101 will be briefly described. First, the external lead electrode 107 of the sensor head 101 and the wiring 131 formed on the external wiring board 130 that can be easily adjusted in position and orientation, such as a flexible printed board, are electrically connected using a conductive material 108 such as solder. . The external wiring board 130 corresponds to the board.

  Here, the external wiring board 130 and the sensor head 101 can be electrically connected in a state where the position and posture can be easily adjusted. Next, the abutting surface 105 of the sensor head 101 is abutted against the abutting member 106, and the sensor head 101 is fixed to the abutting member 106 with an adhesive or the like.

  Here, the position and orientation of the external wiring board 130 on which the sensor head 101 is mounted can be easily adjusted. For this reason, when the abutting surface 105 of the sensor head 101 is abutted against the abutting member 106, the magnitude (Vp-p) of the AB phase analog signal shown in FIG. Can be fixed at the optimum position of the sensor head 101 while adjusting the position and posture of the sensor head 101 so that a so-called Lissajous diagram is a perfect circle.

  Next, the operation of the embodiment of the present invention will be described. Further, when the sensor head 101 is abutted and mounted on the abutting member 106, the position and orientation of the external wiring board 130 on which the sensor head 101 is mounted can be easily adjusted. For this reason, it is possible to fix the sensor head 101 at the optimum position while adjusting the position and orientation of the sensor head 101. Therefore, a good encoder signal can be obtained.

  Further, the abutting surface 105 of the sensor head 101 to the abutting member 106 and the surface of the external extraction electrode 107 of the sensor head 101 are different surfaces. Thereby, the sensor head 101 and the external wiring board 130 can be electrically connected in a state where the position and posture can be easily adjusted. For this reason, reliable electrical connection with high reliability can be achieved.

  In the configuration in which electrical connection and physical fixation are bonded on the same surface side so as to be in direct contact with the copper foil pattern provided on the base substrate as in the conventional example, the sensor head and the scale are adjusted to a desired positional relationship. In addition, it is necessary to establish electrical connection with a conductive paste or a solder material.

  For this reason, in the conventional example, the degree of freedom of mounting is limited, and the electrical connection varies, causing problems in terms of reliability. Here, for example, if the deviation of the light source and the photodetector in the sensor head from the desired position is large, there are cases where a good displacement signal can be obtained by inclining the sensor head with respect to the base substrate.

  In such a case, if electrical connection is preferentially mounted, it cannot be mounted in an optimal arrangement relationship between the head and the scale, and a sufficient displacement signal cannot be obtained. In addition, if priority is given to the arrangement relationship between the head and scale that is optimal for obtaining a good encoder signal, an unstable connection site is generated due to electrical connection, and reliability problems such as disconnection occur.

  On the other hand, in this embodiment, the external lead-out wiring electrode 107 is formed on the surface excluding the abutting surface 105 of the sensor head 101. Therefore, the sensor head and the external wiring can be electrically connected with high reliability while obtaining a good encoder signal.

  Of course, various modifications and changes can be made to each configuration of the embodiment of the present invention. The number of light sources 103 and photodetectors 104 is not limited to one, and a large number may be arranged. Further, the grid pattern of the scale 120 is not limited to one type, and various types may be formed. Further, the photodetector 104 may be mounted in a semiconductor IC, and in addition to the photodetector 104, a circuit for converting an analog signal into a digital signal, an interpolation / division circuit, a light source driver, and the like may be mounted. Furthermore, a structure in which an optical slit is provided on the light source 103 may be employed.

  As a mounting method, the external wiring board 130 may be electrically connected to the sensor head 101 after the sensor head 101 is abutted and mounted on the abutting member 106. In addition, the method of fixing the sensor head 101 to the abutting member 106 is not limited to an adhesive, and it may be fixed by pressing with a leaf spring or the like from the surface of the external wiring board 130 opposite to the sensor head 101 mounting surface. .

  Furthermore, it is not limited to Lin = Lout = Z (Z: desired value). For example, Lin ≠ Lout, and the light source 103 and the light detector 104 may be arranged on the wiring board 109 in a desired relationship without aligning the height of the light emitting surface of the light source 103 and the light receiving surface of the light detector 104. .

  Next, an optical encoder according to Embodiment 2 of the present invention will be described. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. FIG. 3 is a side view of the optical encoder of the present embodiment. FIG. 4 is a perspective view thereof.

  The optical encoder shown in FIGS. 3 and 4 includes a sensor head 101 having a light source 103 and a photodetector 104 inside, and a scale 120 having a lattice pattern 121 that moves linearly relative to the sensor head 101. It is a reflection type optical encoder.

  The difference between the present embodiment and the first embodiment is that a step-shaped groove, that is, a recess 201 is formed as a guide for the abutting position when the sensor head 101 is first abutted against the abutting member 106. Then, the abutting surface 105 of the sensor head 101 is configured to abut against the groove of the recess 201.

  Since other configurations, how to obtain the arrangement relationship of each member, and the mounting method of the sensor head 101 are the same as those in the first embodiment, description thereof is omitted.

  The operation of the present embodiment has the same operation as that of the first embodiment, and further, the concave portion 201 which is the stepped surface of the abutting member 106 serves as a guide for alignment when the sensor head 101 is first abutted. Mounting alignment is easy.

  Each configuration of the present embodiment can be variously modified and changed similarly to the first embodiment.

  Next, an optical encoder according to Embodiment 3 of the present invention will be described. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. FIG. 5 is a perspective view of the optical encoder of the present embodiment.

  The optical encoder shown in FIG. 5 is a reflective type composed of a sensor head 1 having a light source 103 and a photodetector 104 inside, and a scale 120 having a lattice pattern 121 that moves linearly relative to the sensor head 101. It is an optical encoder.

  The difference between the present embodiment and the first embodiment is that the light emitted from the light source 103 is reflected by the scale in the contact area between the abutting surface 105 of the sensor head 101 and the abutting member 106 made of a light shielding material (light shielding structure) 501. Alternatively, it is a region where the reflected or diffracted light is a region that does not block the light related to the displacement signal of the encoder that enters the photodetector 104, and the abutting member 106 blocks light that is not related to the displacement signal as much as possible. is there.

  Since other configurations, how to obtain the arrangement relationship of each member, and the mounting method of the sensor head 101 are the same as those in the first embodiment, description thereof is omitted.

  The operation of the present embodiment has the same operation as that of the first embodiment, and disturbs light to the photodetector 104 by blocking light that is not related to the encoder displacement signal by the abutting member 106 made of the light blocking member 501. Incident can be prevented. For this reason, light with low noise and high S / N is incident on the photodetector 104, and a highly accurate displacement signal is obtained.

  Each configuration of the present embodiment can be variously modified and changed similarly to the first embodiment. In addition, in a region where the light emitted from the light source 103 is reflected or diffracted by the scale and the reflected or diffracted light does not block the light incident on the photodetector 104, resin, glass, or the like that transmits light is not limited to space. May be arranged.

  Next, an optical encoder according to Embodiment 4 of the present invention will be described. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. FIG. 6 is a side view of the optical encoder of the present embodiment. FIG. 7 is a perspective view thereof.

  The optical encoder shown in FIG. 6 is a reflective type composed of a sensor head 101 having a light source 103 and a photodetector 104 inside, and a scale 120 having a lattice pattern 121 that moves linearly relative to the sensor head 101. It is an optical encoder.

  The difference between the present embodiment and the first embodiment is that the distance between the abutting surface 105 of the sensor head 101 and the scale 120 and the inclination (position) are between the abutting member 106 and the abutting surface 105 of the sensor head 101. , Posture), and a thin plate 601 that is an adjustment unit capable of adjusting at least one of them is interposed.

  For example, it is assumed that the theoretical relationship between the Lin length and the Lout length from which a good encoder signal (displacement signal) is obtained is Lin = Lout = Z (Z: desired value). The light source 103 and the photodetector 104 are arranged on the wiring board 109 so that the height of the light emitting surface of the light source 103 and the height of the light receiving surface of the photodetector 104 are aligned.

  Further, the position of the abutting member 106 is determined so that the abutting surface 105 of the sensor head 101 and the lattice pattern 121 surface of the scale 120 are substantially parallel. Here, for example, in the manufacturing process of the sensor head 101, when the light source 103 and the photodetector 104 are mounted on the wiring board 109, the heights of the light emitting surface of the light source 103 and the light receiving surface of the photodetector 104 are shifted. When the sensor head 101 is inclined with respect to the lattice pattern surface 121 of the scale 120 so that Lin = Lout = Z as shown in FIG. 6, a good encoder signal (displacement signal) can be obtained. It will be.

  Therefore, when the abutting surface 105 of the sensor head 101 is abutted against the abutting member 106 and mounted, the magnitude of the AB phase analog signal (Vp-p) or the Lissajous diagram is a perfect circle as described in the first embodiment. The sensor head 101 is horizontally rotated with respect to the lattice pattern surface 121 of the scale 120 or a thin plate 601 is interposed so as to have a shape, and at least one of an interval and an inclination (position, posture) with respect to the lattice pattern surface 121 of the scale 120. Is fixed at the optimum position of the sensor head 101.

  Since other configurations, how to obtain the arrangement relationship of each member, and the mounting method of the sensor head 101 are the same as those in the first embodiment, description thereof is omitted.

  The operation of the present embodiment has the same operation as that of the first embodiment, and is inexpensive, such as a thin plate 601 that adjusts the distance and posture of the sensor head 101 that is optimal with respect to the lattice pattern surface 121 of the scale 120, and the position and An adjustment member whose posture is easily adjustable is interposed between the sensor head 101 and the scale 120. As a result, an optical encoder having a further good encoder signal (displacement signal) can be obtained.

  Further, the adjustment unit may be either a structure formed integrally with the abutting member 106 or a structure formed separately from the abutting member 106. Each configuration of the present embodiment can be variously modified and changed similarly to the first embodiment.

  Furthermore, the inclination direction of the sensor head 101 is not limited to the roll direction with respect to the movement of the scale 120 as shown in FIG. 6, and the thin plate 601 may be interposed so as to be inclined in the pitch direction.

  Next, an optical encoder according to Embodiment 5 of the present invention will be described. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. FIG. 8 is a side view of the optical encoder of the present embodiment. FIG. 9 is a perspective view thereof.

  The optical encoder shown in FIG. 8 is a reflective type composed of a sensor head 1 having a light source 103 and a photodetector 104 inside, and a scale 120 having a lattice pattern 121 that moves linearly relative to the sensor head 101. It is an optical encoder.

  The difference between the present embodiment and the first embodiment is that the abutting member 106 is provided not only on the abutting surface 105 side of the sensor head 101 but also on the side surface of the sensor head 101.

  Since other configurations, how to obtain the arrangement relationship of each member, and the mounting method of the sensor head 101 are the same as those in the first embodiment, description thereof is omitted.

  The operation of this embodiment is the same as that of the first embodiment. Furthermore, by arranging the abutting member 106 not only on the abutting surface 105 side of the sensor head 101 but also on the side surface of the sensor head 101, the mounting position of the sensor head 101 in the direction substantially parallel to the scale lattice pattern surface can be easily adjusted. It becomes.

  Each configuration of the present embodiment can be variously modified and changed similarly to the first embodiment. In each of the above embodiments, the structure of the contact portion with the abutting surface 105 of the abutting member 106 is not limited to a flat surface, but may be a point contact structure as shown in FIG. It is not limited to one surface but may be two or more surfaces.

  As described above, the optical encoder according to the present invention is useful for a reflective optical encoder.

It is a figure which shows the structure of the side cross section of the optical encoder which concerns on Example 1 of this invention. FIG. 2 is a diagram illustrating a perspective configuration of the optical encoder according to the first embodiment. It is a figure which shows the structure of the side cross section of the optical encoder which concerns on Example 2 of this invention. FIG. 10 is a diagram illustrating a perspective configuration of an optical encoder according to a second embodiment. It is a figure which shows the isometric view structure of the optical encoder of Example 3 of this invention. It is a figure which shows the structure of the side cross section of the optical encoder which concerns on Example 4 of this invention. FIG. 9 is a diagram illustrating a perspective configuration of an optical encoder according to a fourth embodiment. It is a figure which shows the structure of the side cross section of the optical encoder which concerns on Example 5 of this invention. FIG. 9 is a diagram illustrating a perspective configuration of an optical encoder according to a fifth embodiment. It is a figure which shows the perspective structure of the modification of an abutting member. It is a figure which shows the cross-sectional structure of the optical encoder of a prior art. It is a figure which shows the signal of an optical encoder. It is a figure which shows the positional relationship of the sensor head of an optical encoder, and a scale.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Optical encoder 101 Sensor head 103 Light source 104 Photo detector 105 Abutting surface 106 Abutting member 107 External extraction electrode 108 Conductive material 109 Wiring board 110 Sensor head 120 Scale 121 Grid pattern 130 External wiring board 131 Wiring 201 Recess 501 Light shielding material 601 Thin plate 91 Head 92 Solder mounting lead 95 Copper foil pattern 97 Base substrate 1 Sensor head 2 Scale

Claims (9)

A sensor head having a light source and a photodetector;
A scale that is displaced relative to the sensor head;
An abutting member for holding the sensor head and the scale in a desired arrangement relationship;
The light emitted from the light source is reflected or diffracted by the scale, the reflected or diffracted light is received by the photodetector, and a displacement signal is output from the sensor head,
An optical encoder characterized in that a surface of the sensor head that faces the scale is an abutting surface that abuts against the abutting member. And a substrate that is electrically connected to the sensor head,
The optical encoder according to claim 1, wherein an external lead-out wiring electrode is formed on a surface excluding the abutting surface of the sensor head to be electrically connected to the substrate.   The optical encoder according to claim 1, wherein the abutting surface side of the sensor head of the abutting member has a step shape. The abutting member is
A transmission region that transmits light of a path that is emitted from the light source, reflected or diffracted by the scale, and incident on the photodetector;
The optical encoder according to claim 1, further comprising: a light shielding structure formed at least at a part or the entire periphery of the transmission region.   The abutting member is an adjustment that adjusts at least one of an interval and an inclination between the abutting surface of the sensor head and the scale at least at a part between the abutting surface of the sensor head and the abutting member. The optical encoder according to claim 1, further comprising a portion.   The optical encoder according to claim 5, wherein the abutting surface of the sensor head is disposed to be inclined with respect to the scale pattern surface of the scale by using the adjustment unit.   The optical encoder according to claim 4, wherein the adjustment unit is a thin plate.   2. The optical encoder according to claim 1, wherein at least one side surface of the sensor head excluding the abutting surface is a abutting surface when mounted on the abutting member.   The optical encoder according to claim 1, wherein the abutting surface of the sensor head is a resin.

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