JP2007333667A - Optical encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reliable optical encoder that reduces mechanical changes in sealing resin, such as cracks and breaks, when a light source and a light source slit are resin-sealed. <P>SOLUTION: The optical encoder 11 has the light source 32, the light source slit 4 for transmitting predetermined portions of light emitted from the light source 32, a scale 2 having a periodic pattern 22 for reflecting or transmitting the light transmitted through the light source slit 4, and a photodetector 5 for receiving the light past the scale 2. The light source 32, photodetector 5 and light source slit 4 are sealed in sealing resin, and a transparent resin member 44 forming the base of the light source slit is an elastic member. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical encoder provided with a displacement sensor using an optical slit.

  2. Description of the Related Art Conventionally, so-called encoders such as an optical type and a magnetic type are used to detect a displacement amount in a linear direction in a machine tool stage, a three-dimensional measuring instrument, and the like. Also in a servo motor or the like, so-called encoders such as an optical type and a magnetic type are used to detect a rotation angle.

  The encoder is generally composed of a scale such as a stage fixed to a member whose displacement is to be detected, and a sensor head for detecting the displacement of the scale. In the case of the optical type, the sensor head detects the movement of the scale by detecting the light beam modulated by the scale. In the case of a magnetic system, the movement of the scale is detected by detecting magnetic information formed on the scale.

  A typical conventional example will be described with reference to FIG. The encoder according to this conventional example is described in Patent Document 1, for example.

  FIG. 17 shows the basic configuration of this conventional example. The light emitted from the coherent light source 71 is narrowed by the slit 75. The light that has passed through the opening 76 of the slit 75 is projected onto the photodetector 73 via the scale 72.

  The distance between the slit 75 and the scale 72 is z1, the distance between the scale 72 and the photodetector 73 is z2, the pitch of the scale 72 is p1, the wavelength of the light beam emitted from the light source is λ, and n is an integer. When the relationship (1) is established, a light / dark pattern is formed on the photodetector 73.

1 / z1 + 1 / z2 = λ / (n × p1 ² ) (1)
Therefore, if the light receiving portions 74 are arranged on the photodetector 73 at a period at which this light / dark pattern can be detected, the displacement of the scale 72 can be detected.

  Next, another conventional example will be described. 18 and 19 show an example of a light source with a light source slit in which a light source slit having a slit opening 85a in the emission direction of a light beam emitted from the light source 80 and the light source 80 are integrally sealed with a sealing resin 81. FIG. .

  A light source with a light source slit, which is a second conventional example, is described in Patent Document 2, for example. The light source slit also serves as power supply wiring to the light source 80 and is formed of a metal plate. The light source slit is enclosed in the sealing resin 81 together with the light source 80, thereby enabling a small light source with a slit.

JP 2004-239825 A Japanese Patent Laid-Open No. 2001-135862

  However, the conventional techniques have the following problems. In the second conventional example, a light source slit 85 and a light source 80 are sealed in a sealing resin 81 to form a light source with a light source slit. The metal plate in which the slit opening (hole) 85 a is formed has a larger elastic modulus than the sealing resin 81. Further, the linear expansion coefficients of the sealing resin 81 and the metal plate are different from each other. For this reason, there has been a problem that the sealing resin 81 is damaged or cracked due to a change in temperature during manufacturing or use.

  That is, due to shrinkage of the sealing resin during thermal curing, stress is generated at the interface between the light source slit 75 and the sealing resin 81 and stress generated at the same interface due to temperature changes in the usage environment. There was a problem of cracks during use.

  As described above, when the sealing resin 81 is broken or cracked, the reliability of the light source 80 is lowered. In addition, the encoder performance is deteriorated by affecting the optical path of light from the light source.

  The present invention has been made in view of the above, and when the light source and the light source slit are resin-sealed, mechanical changes of the sealing resin, for example, cracks and breakage are reduced, and a highly reliable optical type An object is to provide an encoder.

  In order to solve the above-described problems and achieve the object, according to the present invention, a light source, a light source slit that transmits a predetermined portion of light emitted from the light source, and light that has passed through the light source slit is reflected or transmitted. An optical encoder having a scale on which a periodic pattern is formed and a photodetector that receives light passing through the scale, and the light source, the photodetector, and the light source slit are sealed in a sealing resin, An optical encoder characterized in that the base material of the light source slit is made of an elastic member can be provided.

  According to a preferred aspect of the present invention, the first light source, the first grating that transmits a predetermined portion of the light emitted from the light source, and the periodic pattern that reflects the light that has passed through the first grating are formed. An optical device having a second grating and a photodetector having the function of a third grating for detecting a periodic light-dark pattern projected on the photodetector by light reflected or diffracted by the second grating The first grating is a light source slit whose base material is an elastic member, and the photodetector has a light receiving element array capable of detecting a predetermined phase portion of a light-dark pattern, and the light source and the first It is desirable that the grating and the photodetector are integrally sealed in a sealing resin.

  Moreover, according to a preferred aspect of the present invention, it is desirable that the elastic member has a characteristic that does not cause a mechanical change inside the sealing resin.

  Moreover, according to a preferred aspect of the present invention, it is desirable that the elastic modulus of the base material of the light source slit is substantially equal to or smaller than the elastic modulus of the sealing resin.

  Further, according to a preferred aspect of the present invention, the light source slit has a slit pattern formed on the surface of the base material that transmits light emitted from the light source by a member that blocks light emitted from the light source. It is desirable to have a feature.

  Further, according to a preferred aspect of the present invention, it is desirable that the member of the light source slit that blocks light emitted from the light source is a metal thin film.

  According to a preferred aspect of the present invention, the light source slit is characterized in that a hole that transmits light emitted from the light source is formed in a base material that blocks light emitted from the light source. Is desirable.

  Moreover, according to a preferable aspect of the present invention, it is desirable that the light source slit is attached to the light source, and the light source and the light source slit are integrally sealed in the sealing resin.

  Moreover, according to a preferable aspect of the present invention, it is desirable that the base material of the light source slit is attached on the photodetector and attached so as to protrude on the light source.

  Moreover, according to a preferable aspect of the present invention, it is desirable that the base material of the light source slit is attached in a bridge shape so as to be in contact with both the light source and the photodetector.

  Moreover, according to a preferable aspect of the present invention, it is desirable that the base material of the light source slit is a resin material.

  According to a preferred aspect of the present invention, it is desirable that the surface of the light source slit on which the slit pattern is formed is opposite to the light source.

  Moreover, according to a preferred aspect of the present invention, it is desirable that the refractive index of the base material of the light source slit is substantially equal to the refractive index of the sealing resin.

  Further, according to a preferred aspect of the present invention, the light source slit base material has a light shielding part on the optical path of the light reflected from the interface of the sealing resin, and the light emitted from the light source is reflected at the interface of the sealing resin. It is desirable to be characterized.

  Moreover, according to a preferable aspect of the present invention, it is desirable that the linear expansion coefficient of the base material of the light source slit is substantially equal to the linear expansion coefficient of the sealing resin.

  Moreover, according to a preferable aspect of the present invention, it is desirable that the Vickers hardness of the base material of the light source slit is substantially equal to or smaller than the Vickers hardness of the sealing resin.

  ADVANTAGE OF THE INVENTION According to this invention, when a light source and a light source slit are resin-sealed, there exists an effect that the mechanical change of sealing resin, for example, a crack and breakage, can be reduced and a highly reliable optical encoder can be provided.

  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 perspective view of a reflective optical encoder 11 according to Embodiment 1 of the present invention. Embodiment 1 of the present invention will be described with reference to FIGS. The encoder head 1 has a light source 32 and a photodetector 5. In addition, a periodic pattern 22 that is a periodic optical pattern is formed on the scale 2.

  First, the configuration of the present embodiment will be described. As shown in FIG. 2, the encoder head 1 in this embodiment has a light source 32 that emits light of a predetermined wavelength and a photodetector 5 mounted on a substrate 100. On the light source 32, further, a light source slit 4 is mounted, which is made of a transparent resin member 44 and has a light source slit pattern 42 formed on one surface thereof. The transparent resin member 44 corresponds to the base material.

  The transparent resin base material 44 uses a PET film in this embodiment. The light source 32, the photodetector 5, and the light source slit 4 are packaged so as to be covered with a sealing resin 102. The energization to the light source 32 and the signal output wiring from the light detector 5 can be connected to the outside via the substrate 100 by electrical wiring (not shown).

  Next, the operation of this embodiment will be described. The light emitted from the light source 32 passes through the light source slit 4 disposed on the light source 32 and is irradiated toward the periodic pattern 22 formed on the scale 2. The light applied to the periodic pattern 22 of the scale 2 is reflected here and applied to the light receiving element group 52 formed on the photodetector 5.

Here, as shown in FIG. 2, the distance between the light source slit 4 and the periodic pattern 22 is z1, and the distance between the periodic pattern 22 and the photodetector 5 is z2. Further, the wavelength of the light emitted from the light source 32 is λ, the pitch (period) of the periodic pattern 22 on the scale 2 is p1, and n is a natural number, and they are arranged so that the relationship of Expression (1) is established. As a result, a light / dark pattern similar to the periodic pattern 22 on the scale 2 is projected onto the light receiving surface of the photodetector 5.
1 / z1 + 1 / z2 = λ / (n × p1 ² ) (1)

Here, on the light source slit 4, a light source slit pattern 42 in which a light transmission part and a light shielding part are periodically formed is formed. This pitch Pslit is calculated by the following equation (2).
Pslit = (z1 + z2) × p1 / z2 (2)

Furthermore, the pitch p2 of the light / dark pattern similar to the scale 2 projected onto the photodetector 5 is calculated by the following equation (3).
p2 = (z1 + z2) × p1 / z1 (3)

  At this time, a light and dark pattern similar to the scale 2 moves on the photodetector 5 according to the movement of the scale 2. Therefore, the movement of the scale 2 can be detected by detecting the movement of the light / dark pattern by the light receiving element group 52 formed on the photodetector 5.

  A method for manufacturing the encoder head 1 according to this embodiment will be described. As shown in FIGS. 1 and 2, the light source 32 and the photodetector 5 are first attached on the substrate 100. As shown in FIG. 4, the light source 32 in this embodiment has a structure in which a semiconductor light source 34 made of a semiconductor bare chip is mounted on a substrate 36 and is sealed with a second sealing resin 104. The photodetector 5 is constituted by a semiconductor substrate.

  Next, the light source slit 4 is attached to the upper surface of the light source 32. Finally, the whole is covered with a sealing resin 102 which is a thermosetting resin, and is cured by heating and curing. In general, since a thermosetting resin has a binder, it contracts greatly at the stage of heat curing because it volatilizes. The degree of shrinkage varies depending on the sealing resin, but generally shrinks by several tens of percent.

  The features of this embodiment will be described. The encoder head 1 is used for various purposes. Moreover, the environment used is also various according to a use. For example, when it is attached to a machine tool, it may be used at an environmental temperature of about 40 to 50 ° C. in summer. On the other hand, in winter, it may be used at temperatures near zero. When exposed to such an environment, the sealing resin 102 expands and contracts according to a specific linear expansion coefficient.

  In general, the linear expansion coefficient of the sealing resin is about one digit larger than that of a semiconductor substrate or a glass plate. For this reason, when such a temperature difference occurs, distortion occurs in the sealing resin, and in some cases, mechanical changes such as cracks occur. This tendency can be made relatively thin, and is particularly great around the light source slit 4 arranged at a relatively higher position than around the photodetector 5 and the light source 32 that are in contact with the substrate 100. In this embodiment, since the surface of the light source 32 that contacts the light source slit 4 is also the sealing resin 102 as shown in FIG. 4, the light source slit 4 has a structure that floats in the sealing resin. .

  If the light source slit 4 is made of a member such as glass that has a linear expansion coefficient that is significantly different from that of the sealing resin, a structure in which a glass plate that does not expand and contract in a resin having a large expansion / contraction amount floats. . Therefore, a crack as shown in FIG. 3 may occur in the sealing resin 102 due to the stress generated by the expansion and contraction.

  In the present embodiment, the light source slit 4 is also made of a resin material having a linear expansion coefficient close to that of the sealing resin 102, and the light source slit pattern 42 is formed of a metal thin film on the surface thereof. Therefore, no stress due to expansion or contraction occurs even when the environmental temperature changes. Since expansion and contraction are performed integrally, the occurrence of cracks and the like can be minimized.

  Here, the linear expansion coefficient of the material for forming the light source slit pattern 42 on the surface of the light source slit 4 is not necessarily equal to that of the sealing resin 102 or the like. However, the light source slit pattern 42 is sufficiently thin and has an opening such as a slit. For this reason, in this embodiment, a strong distortion that leads to a crack does not occur.

  Furthermore, in this embodiment, the sealing resin 102 and the transparent resin member 44 of the light source slit 4 are selected so that their elastic moduli are substantially equal. Therefore, even when a stress is generated due to shrinkage during heating curing during the manufacture, the sealing resin 102 and the transparent resin member 44 of the light source slit 4 have substantially the same deformation ratio with respect to the stress. For this reason, stress does not concentrate locally, and it is possible to reduce the occurrence of cracks during manufacturing.

  At the time of manufacture, the sealing resin 102 material is a liquid having a predetermined viscosity and is cured by heat curing. In general, the sealing resin material becomes soft at a high temperature of 100 ° C. or higher. That is, the elastic modulus becomes very small.

  The elastic modulus mentioned here is a proportional multiplier between stress and strain, and means that a smaller numerical value is softer. It is defined as Young's modulus in the case of deformation against tensile force or compressive force, rigidity modulus in the case of deformation against shearing force, and bulk modulus in the case of deformation against hydrostatic pressure.

  In this way, by configuring as in the present embodiment, it is possible to minimize the occurrence of cracks due to stress even when the environmental temperature or the like changes. In addition, the occurrence of cracks during manufacturing can be sufficiently reduced.

  Furthermore, in this embodiment, the refractive indexes of the transparent resin member 44 of the light source slit 4 and the sealing resin 102 can be selected to be substantially equal. With this configuration, the optical characteristics of the optical path from the light source 32 to the scale 2 and the optical path from the scale 2 to the photodetector 5 are substantially equal, so that the encoder characteristics can be made more stable.

  Preferably, the transparent resin member 44 that is a base material of the light source slit has an elastic modulus substantially equal to or smaller than that of the sealing resin 102 in an environment where the optical encoder is used. For example, when the optical encoder is used at an ambient environment temperature of 50 ° C., a material is selected so that the elastic moduli of both members at 50 ° C. are approximately equal. Thereby, it can prevent that a crack etc. arise in the inside of sealing resin 102 in use environment.

  Next, the form of Example 2 of this invention is demonstrated, referring FIG. 5, FIG. FIG. 5 is a perspective view of the reflective optical encoder 12 according to the second embodiment. FIG. 6 shows a cross-sectional view of the encoder head 1. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  The basic configuration is the same as that of the first embodiment, and the basic operation is the same as that of the first embodiment. The configuration of the second embodiment of the present invention is that the light source slit 4 is mounted not on the light source 32 but on the photodetector 5 and has a length reaching the adjacent light source 32. Different from form.

  In the second embodiment of the present invention, as shown in FIGS. 5 and 6, the photodetector 5 and the light source 32 are mounted on the substrate 100. Further, a light source slit 4 is attached to the photodetector 5. The light source slit 4 is composed of a transparent resin member 44 made of a resin material having substantially the same elastic modulus as that of the sealing resin 102.

  On the surface of the transparent resin member 44, a light source slit pattern 42 made of a metal film or the like is formed on the surface facing the light source 32. The light source slit pattern 42 is disposed on the optical path where the light emitted from the light source 32 is directed to the periodic pattern 22 of the scale 2, and the periodic pattern 22 is not provided in other regions.

  By configuring in this way, the features of the embodiment 1 are provided as they are, and further, the distance z1 from the light source slit pattern 42 to the periodic pattern 22 of the scale 2 and the light receiving surface of the photodetector 5 from the scale pattern 22 It is possible to easily make the distance z2 of the same.

  That is, in the above-described formulas (2) and (3), z1 = z2 can be easily set. By doing in this way, Formula (2) and Formula (3) can be expressed as follows, respectively.

Pslit = 2 × p1 (2 ′)
p2 = 2 × p1 (3 ′)

  Thus, z1 and z2 can be removed from the equations (2) and (3). In other words, the ideal pitch Pslit of the light source slit pattern 42 and the pitch p2 of the light / dark pattern formed on the photodetector 5 are constant regardless of the positional relationship between the encoder head 1 and the scale 2. Therefore, the encoder signal becomes more stable.

  In the conventional method, when glass or the like is used for the base material of the light source slit 4 in such a configuration, a crack as shown in FIG. 7 may occur. However, in the present embodiment, as in the first embodiment, the transparent resin member 44 of the light source slit 4 is made of a resin member having an elastic modulus substantially equal to that of the sealing resin 102, so that the occurrence of cracks can be suppressed. Become.

  By configuring as described above, it is possible to realize the characteristic of the first embodiment and a more stable encoder signal.

  Next, the form of Example 3 of this invention is demonstrated, referring FIG. FIG. 8 is a cross-sectional view of the reflective optical encoder 13 according to the third embodiment. In addition, the same code | symbol is attached | subjected to the part same as Example 1, and the overlapping description is abbreviate | omitted.

  In this embodiment, the basic configuration is the same as that of the first embodiment, and the basic operation is the same as that of the first embodiment. The third embodiment of the present invention is different from the first embodiment in that the light source slit 4 is in contact with both the light detector 5 and the light source 32 instead of the light source 32.

  On the substrate 100, the photodetector 5 and the light source 32 are directly attached. The heights of the light detector 5 and the light source 32 are set to be substantially equal, and the light source slit 4 is attached so as to be in contact with both the light detector 5 and the light source 32 and to bridge the bridge. The light source slit pattern 42 of the light source slit 4 is formed on the surface facing the light source 32.

  With this configuration, the height of the light receiving element group 52 formed on the photodetector 5 and the height of the surface of the light source slit pattern 42 formed on the light source slit 4 can be made substantially equal. Thereby, the distance z1 and z2 are made the same, and the same effect as Example 2 is acquired. Further, since both ends of the light source slit 4 are held, the influence of the height deviation due to the deflection of the light source slit 4 or the like is reduced, and the strength is further stabilized.

  By configuring as described above, it is possible to realize an encoder signal that has the characteristics of the form of the first embodiment and that is more stable and more accurate and stronger than the form of the second embodiment. .

  Next, the form of Example 4 of this invention is demonstrated, referring FIG. 9, FIG. FIG. 9 shows a cross-sectional configuration of the reflective optical encoder 14 according to the embodiment 4 of the present invention. FIG. 10 shows a perspective configuration of the light source slit 4 of the fourth embodiment.

  In addition, the same code | symbol is attached | subjected to the part same as Example 1, and the overlapping description is abbreviate | omitted. In this embodiment, the basic configuration is the same as that of the first embodiment, and the basic operation is the same as that of the first embodiment. The fourth embodiment of the present invention is different from the first embodiment in that the light source slit 4 is configured by providing a through hole 48 in a light-blocking resin member 46.

  In the present embodiment, the light source slit 4 configured by providing the through hole 48 in the light shielding resin 46 is attached to the upper surface of the light source 32. As the light-shielding resin 46, a member whose elastic modulus is substantially equal to or smaller than that of the sealing resin 102 is selected.

  In the light source slit 4 having this configuration, patterning with a metal thin film as in the first embodiment is not required. Therefore, it is possible to form the light source slit 4 with only the resin material. As a result, the environmental change and the magnitude of internal stress generated during manufacturing are further reduced.

  By configuring as described above, it is possible to minimize the occurrence of cracks due to stress even when the environmental temperature or the like changes. Furthermore, the occurrence of cracks during manufacturing can be further reduced as compared with the form of the first embodiment.

  Next, the form of Example 5 of this invention is demonstrated, referring FIG. FIG. 11 is a sectional view of a reflective optical encoder 15 according to the fifth embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the part same as Example 1, and the overlapping description is abbreviate | omitted.

  In this embodiment, the basic configuration is the same as that of the first embodiment, and the basic operation is the same as that of the first embodiment. The form of Example 5 is a modification of the form of Example 1, and the point that the light source slit 4 is attached to the light source 32 is the same as that of Example 1.

  This embodiment is different from the embodiment 1 in that a light shielding portion 43 is formed at one end of the light source slit 4 facing the photodetector 5 of the transparent resin base material 44.

  In the present embodiment, the light-shielding portion 43 employs a member having approximately the same degree of linear expansion coefficient and substantially the same elastic modulus as the transparent resin base material 44 of the light source slit 4. The light shielding portion 43 may be a metal thin film similar to the light source slit pattern 42 of the light source slit 4.

  In the form of the first embodiment of the present invention, a part of the light emitted from the light source 32 is reflected at the interface 45 with the air like the light beam L indicated by the arrow in FIG. For this reason, the light beam L passes through an optical path (path) that directly enters the photodetector 5 without being output from the encoder head 1 to the outside.

  Such a light beam L is light that does not include information on the scale 2, and relatively reduces the ratio of signal components of the encoder. In addition, the light beam L becomes noise light, which degrades the performance as an encoder.

  By forming the light shielding part on the optical path of the light reflected at the interface of the sealing resin, the light beam L emitted from the light source 32 travels in the direction of the arrow shown in FIG. For this reason, it does not proceed to the path shown by the broken line.

  Therefore, it is possible to remove a component that is reflected inside the encoder head 1 and directly enters the light receiving unit group 52 of the photodetector 5. By configuring in this way, it is possible to realize an encoder that has the characteristics of the form of the first embodiment as it is and that does not have a decrease in signal level due to internal reflection of the encoder head 1.

(Modification)
Moreover, the modification of the form of Example 5 of this invention is shown in FIGS. 12-16. In the example shown in FIGS. 12 and 13, instead of the light shielding portion 43, a part of the metal thin film forming the light source slit pattern 42 of the light source slit 4 is used as a mask pattern without an opening.

  The light beam L emitted from the light source 32 and internally reflected is blocked by the mask pattern and does not enter the light receiving unit group 52 of the photodetector 5. Although the basic effect is the same as that of the fifth embodiment, the present modification is easier to manufacture and is advantageous in terms of cost.

  FIG. 14 shows another modification of the fifth embodiment. The light source slit 4 has a light-shielding portion 43 and is configured to be in contact with both the light source 32 and the photodetector 5 as in the embodiment 3 as shown in the figure. According to the present embodiment, it is possible to realize the encoder head 1 while maintaining the characteristics of the embodiment 3 and removing the influence of the internal reflection of the encoder head.

  15 and 16 are modifications of the embodiment shown in FIG. The difference is that the light-shielding portion 43 is formed by the metal thin film forming the light source slit pattern 42 of the light source slit 4 while the light source slit 4 is in contact with both the light source 32 and the photodetector 5.

  With this configuration, it is possible to easily create the encoder head 1 that eliminates the influence of internal reflection of the encoder while maintaining the characteristics of the third embodiment of the present invention.

  In the embodiment described so far, the light source 32 has been described by taking a resin-sealed LED light source as shown in FIG. 4 as an example. However, the present invention is not limited to this. For example, a semiconductor laser light source such as a VCSEL, an SLD, a current confining type LED, or the like can be used. In addition to the resin-sealed one, it can be used for various mounting forms such as a can package product and a bare chip.

  Furthermore, as for the mounting form, the light source 32, the light detector 5, and the light source slit 4 are arranged on the substrate 100 and sealed with the sealing resin 102. However, the present invention is not limited to this. If the mounting form uses a sealing resin, such as a mold package using a lead frame, it is possible to enjoy the effects of the present invention.

  In the present embodiment, the elastic modulus is described as an example of the hardness of the member. However, if the method can confirm that the sealing resin and the light source slit member have the same degree of hardness, for example, Vickers hardness, etc. Any method of hardness can be used.

  The present invention can be variously modified and modified without departing from the scope of the invention, and the embodiment described above is only an example.

  As described above, the optical encoder according to the present invention is useful when the light source and the light source slit are sealed with resin.

1 is a perspective view of a reflective optical encoder of Example 1. FIG. FIG. 3 is a diagram illustrating a cross-sectional configuration of the encoder head according to the first embodiment. It is a mode that the crack generate | occur | produced in the encoder head. 1 is a diagram illustrating a light source of Example 1. FIG. 6 is a perspective view of a reflective optical encoder of Embodiment 2. FIG. 6 is a cross-sectional view of an encoder head according to Embodiment 2. FIG. It is a mode that the crack generate | occur | produced in the encoder head. 7 is a cross-sectional view of a reflective optical encoder of Example 3. FIG. 7 is a cross-sectional view of a reflective optical encoder of Example 4. FIG. 6 is a perspective view of a light source slit of Example 4. FIG. It is the time of the cross section of the reflective optical encoder of Example 5. FIG. 10 is a cross-sectional view of a reflective optical encoder according to a modification of Example 5. FIG. 10 is a top view of a reflective optical encoder according to a modification of the fifth embodiment. FIG. 10 is a cross-sectional view of a reflective optical encoder according to a modification of Example 5. FIG. 10 is a cross-sectional view of a reflective optical encoder according to a modification of Example 5. FIG. 10 is a top view of a reflective optical encoder according to a modification of the fifth embodiment. It is a figure which shows the basic composition of the conventional reflection type optical encoder. It is a figure which shows the light source with the conventional light source slit. It is a figure which shows the light source with the conventional light source slit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Encoder head 2, 72 Scale 4, 75 Light source slit 5, 73 Photodetector 11, 12, 13, 14, 15 Reflection type optical encoder 22 Periodic pattern 32, 80 Light source 34 Semiconductor light source 36, 100 Substrate 42 Light source slit pattern 43 light shielding portion 44 transparent resin base material 45 interface 46 light shielding resin member 48 through hole 52 light receiving element 71 coherent light source 74 light receiving portion 76 opening portion
81, 102, 104 Sealing resin 85a Slit opening 85 Light source slit 100 Substrate

Claims (16)

A light source;
A light source slit that transmits a predetermined portion of the light emitted from the light source;
A scale on which a periodic pattern that reflects or transmits light transmitted through the light source slit is formed;
A light detector that receives light via the scale, and an optical encoder comprising:
The light source, the photodetector and the light source slit are sealed in a sealing resin,
The optical encoder is characterized in that a base material of the light source slit is made of an elastic member. A light source;
A first grating that transmits a predetermined portion of light emitted from the light source;
A second grating formed with a periodic pattern that reflects light that has passed through the first grating;
And a photodetector having a third grating function for detecting a periodic bright and dark pattern projected on the photodetector by light reflected or diffracted by the second grating. And
The first lattice is a light source slit whose base material is an elastic member,
The photodetector has a light receiving element array capable of detecting a predetermined phase portion of a light and dark pattern,
The optical encoder, wherein the light source, the first grating, and the photodetector are integrally sealed in a sealing resin.   The optical encoder according to claim 1, wherein the elastic member has a characteristic that does not cause a mechanical change in the sealing resin.   The optical encoder according to claim 1, wherein an elastic modulus of the base material of the light source slit is substantially equal to or smaller than an elastic modulus of the sealing resin.   The light source slit has a slit pattern formed on a surface of a base material that transmits light emitted from the light source, by a member that blocks light emitted from the light source. The optical encoder according to any one of   The optical encoder according to claim 5, wherein the member that shields light emitted from the light source of the light source slit is a metal thin film.   The said light source slit is a base material which shields the light radiate | emitted from the said light source, The hole part which permeate | transmits the light radiate | emitted from the said light source is formed in any one of Claims 1-3 characterized by the above-mentioned. The optical encoder according to item.   The optical encoder according to claim 1, wherein the light source slit is attached to the light source, and the light source and the light source slit are integrally sealed in a sealing resin. .   The optical source according to any one of claims 1 to 6, wherein a base material of the light source slit is attached on the photodetector and attached so as to project on the light source. Encoder   The optical type according to any one of claims 1 to 6, wherein a base material of the light source slit is attached to a bridge shape so as to contact both the light source and the photodetector. Encoder.   The optical encoder according to any one of claims 1 to 10, wherein a base material of the light source slit is a resin material.   The optical encoder according to any one of claims 8 to 10, wherein a surface of the light source slit on which the slit pattern is formed is opposed to the light source.   The optical encoder according to claim 12, wherein a refractive index of a base material of the light source slit is substantially equal to a refractive index of the sealing resin.   The base material of the light source slit has a light-shielding portion on an optical path of light that is reflected from the interface of the sealing resin and emitted from the light source, and that travels toward the photodetector. Item 14. The optical encoder according to any one of Items 1 to 13.   The optical encoder according to any one of claims 1 to 14, wherein a linear expansion coefficient of a base material of the light source slit is substantially equal to a linear expansion coefficient of the sealing resin.   The optical encoder according to claim 1, wherein a Vickers hardness of a base material of the light source slit is substantially equal to or smaller than a Vickers hardness of the sealing resin.

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