JP2019002810A - Light receiver and photoelectric encoder having the same - Google Patents

Abstract

To provide a light receiver that suppresses separation of a protective member from a light receiving element to maintain the reliability and attains a higher accuracy.SOLUTION: A light receiver 4 includes: a base part 5 serving as the base; a plate-like light receiving element 6 having a plate surface 61 on one side in contact with the base part 5 for receiving light; a plate-like protective member for protecting the light receiving element 6, the protective member having a plate surface 71 in contact with a plane surface 62 on another side of the light receiving element 6; a fixing member 8 for fixing the protective member 7 to the light receiving element 6; and an area expansion unit 9 for expanding an area that contacts with the fixing member 8 until the area becomes larger than the total area of a side surface 60 of the light receiving element 6 and a side surface 70 of the protective member 7. The fixing member 8 fixes the side surface 60 of the light receiving element 6, the side surface 70 of the protective member 7, and the area expansion unit 9.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light receiving device and a photoelectric encoder including the same.

  Conventionally, a photoelectric encoder that includes a scale having a scale and a head that relatively moves along the scale and detects the relative movement amount between the scale and the head is known. The head includes a light source that irradiates light to the scale and a light receiving device that includes a light receiving element that receives light emitted from the light source via the scale. The scale and the light receiving device include a protection member that protects the scale and the light receiving element from external dirt and the like.

For example, an optical displacement detection device (photoelectric encoder) described in Patent Document 1 includes an illumination unit (light source), a main scale (scale), and a light receiving element disposed on the opposite side of the illumination unit across the main scale. (Light receiving device). The light receiver includes a substrate (base) serving as a basis of the light receiver, a light receiving element disposed on a plate surface of the substrate facing the main scale, a cover plate (protective member) that protects the light receiving surface of the light receiving element, and a substrate And a heat resistant resin (fixing member) for fixing the light receiving element and the cover plate.
A cover plate is directly attached to the light receiving surface of the light receiving element via a translucent adhesive. The heat-resistant resin comes into contact with the outer surface of the substrate, the light receiving element and the cover plate except the light receiving surface of the light receiving element to which the cover plate is attached and the plate surface of the cover plate facing the main scale. It is fixed to.

JP-A-9-189514

However, in such a photoelectric encoder, a gap may be formed between the protective member and the fixing member. This gap becomes a passage through which moisture, air, or the like enters the inside of the light receiving device. By passing through this passage, moisture or air may enter between the light receiving element and the protective member. The intruded moisture, air, or the like has a problem that the protective member is lifted off from the light receiving element.
Further, moisture, air, or the like that has entered between the protective member and the light receiving element may refract light received by the light receiving element. For this reason, the photoelectric encoder has a problem that the measurement accuracy cannot be maintained.

  An object of the present invention is to provide a light receiving device that can suppress the peeling of a protective member from a light receiving element to maintain reliability and achieve high accuracy.

  The light receiving device of the present invention has a base that is a base, a plate-shaped light receiving element that receives light while the plate surface on one side is in contact with the base, and a plate surface that is in contact with the plate surface on the other side of the light receiving element. The light receiving device includes a plate-shaped protective member that protects the light receiving element and a fixing member that fixes the protective member to the light receiving element, and is fixed more than the total area of the side surface of the light receiving element and the side surface of the protective member. An area expanding portion that expands a contact area with the member is provided, and the fixing member is fixed over the base, the side surface of the light receiving element, the side surface of the protection member, and the area expanding portion.

  Here, the total area of the side surface of the light receiving element and the side surface of the protection member is the total area of the side surface of the light receiving element and the side surface of the protection member that are not processed. Further, the fixing member is, for example, a resin of a translucent material or an adhesive. Moreover, an area expansion part is a board surface of the protection member facing a scale, for example. Or an area expansion part is the rough surface etc. which were provided by processing a protection member etc., for example.

  According to the present invention, the area extending portion can expand the contact area with the fixing member rather than the total area of the side surface of the light receiving element and the side surface of the protective member. Can be long. Therefore, the light receiving device suppresses separation of the protective member from the light receiving element and prevents intrusion of moisture, air, and the like, as compared with the case where the area extending portion is not provided, and maintains reliability and high accuracy. be able to.

For example, when the area expanding portion is the plate surface of the protection member facing the scale, the fixing member is fixed across the base, the light receiving element, the protection member, and the plate surface of the protection member facing the scale. By doing so, since it will be in the state which covers the plate | board surface of the protection member facing a scale, it can seal and can protect a protection member. Therefore, the light receiving device can suppress a passage through which moisture, air, or the like enters between the protective member and the fixing member, and can prevent the protective member from peeling from the light receiving element.
For example, when the area expanding portion is a rough surface provided by processing the protective member, the area expanding portion can be easily processed.

  At this time, the area expanding portion is preferably provided on the side surface of the protection member.

  Here, for example, when the area expansion portion is the plate surface of the protective member facing the scale, when irregularities due to the fixing member or the like are formed on the incident surface of the light receiving device on which light from the light source through the scale is incident, The light is incident on the light receiving element while being refracted by the unevenness. In addition, for example, when the area expanding portion is a rough surface processed on the plate surface of the protective member facing the scale, the rough surface causes unevenness on the incident surface, and light is refracted by the unevenness and is reflected on the light receiving element. Incident. In these cases, there is a problem that the photoelectric encoder cannot maintain accuracy.

  However, according to the present invention, since the area expanding portion is provided on the side surface of the protection member, the unevenness or rough surface due to the fixing member is not formed on the incident surface of the light receiving device on which light from the light source through the scale is incident. . Therefore, the photoelectric encoder can achieve high accuracy.

  In addition, by providing the area expanding portion on the side surface of the protection member, the area that contacts the fixing member can be expanded more than the total area of the side surface of the light receiving element and the side surface of the protection member. In addition, the area extending portion expands the contact area with the fixing member even if a passage through which moisture, air, or the like enters is generated between the protective member and the fixing member. The distance can be increased. Therefore, the light receiving device can suppress a passage through which moisture, air, or the like enters between the protective member and the fixing member, and can prevent the protective member from peeling from the light receiving element.

  In this case, the area expansion portion is provided on the entire side surface of the protection member.

  According to such a configuration, the area extending portion is provided on the entire side surface of the protection member, so that the area in contact with the fixing member can be expanded more than the total area of the side surface of the light receiving element and the side surface of the protection member. it can. In addition, the area extending portion expands the contact area with the fixing member even if a passage through which moisture, air, or the like enters is generated between the protective member and the fixing member. The distance can be increased. Therefore, the light receiving device can suppress a passage through which moisture, air, or the like enters between the protective member and the fixing member, and can further suppress peeling of the protective member from the light receiving element.

  In this case, the area expanding portion is the plate surface on the other side of the protective member on the side opposite to the plate surface on the one side of the protective member relative to the plate surface on the one side of the protective member in contact with the plate surface on the other side of the light receiving element. It is preferable to be provided so as to reduce the area.

  According to such a configuration, the area expanding portion is formed on the protective member on the side opposite to the plate surface on the one side of the protective member with respect to the plate surface on the one side of the protective member in contact with the plate surface on the other side of the light receiving element. Since it is provided so that the area of the plate surface on the other side is reduced, the structure is such that the protective member and the light receiving element are sandwiched between the fixing member and the base portion, and it is possible to strengthen the external force. Therefore, the light receiving device can suppress a passage through which moisture, air, or the like enters between the protective member and the fixing member, and can further suppress peeling of the protective member from the light receiving element.

  The photoelectric encoder of the present invention includes a light source that emits light, a scale that emits light from the light source, and the above-described light receiving device that receives light from the light source via the scale.

  According to the present invention as described above, the photoelectric encoder includes the light receiving device according to the present invention, so that reliability in measurement can be maintained and measurement accuracy can be improved.

Sectional drawing which shows the encoder provided with the light-receiving device which concerns on 1st Embodiment of this invention. The figure which shows the manufacturing process of the light-receiving device which concerns on 1st Embodiment of this invention. Sectional drawing which shows the encoder provided with the light-receiving device which concerns on 2nd Embodiment of this invention. Sectional drawing which shows the encoder provided with the light-receiving device which concerns on 3rd Embodiment of this invention. Sectional drawing which shows the encoder provided with the light-receiving device which concerns on 4th Embodiment of this invention. Sectional drawing which shows the light-receiving device which concerns on the modification of this invention

[First Embodiment]
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment of the invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an encoder including a light receiving device according to a first embodiment of the present invention.
As shown in FIG. 1, the encoder 1 includes a light source 2 that emits light, a scale 3 that is disposed facing the light source 2 and that is irradiated with light from the light source 2, and a light source 2 that passes through the scale 3. And a light receiving device 4 that receives the light and converts the received light into an electrical signal.

The scale 3 is formed in a long shape with a translucent material such as glass. The scale 3 includes a scale (not shown) along the longitudinal direction of the scale 3 (left and right direction on the paper surface).
When the light from the light source 2 is applied to the light receiving device 4 through the scale of the scale 3, interference fringes having the same period as the scale are generated on the light receiving device 4.
The light source 2 is, for example, a light emitting diode.

In the light receiving device 4, the base 5 serving as a base, the plate surface 61 on one side is in contact with the base 5, the plate-shaped light receiving element 6 that receives light, and the plate surface 62 on the other side of the light receiving element 6 are in contact. A plate-shaped protection member 7 having a plate surface 71 and protecting the light receiving element 6, a fixing member 8 that fixes the protection member 7 to the light receiving element 6, and a frame body 10 that defines the shape of the fixing member 8. Prepare.
The base 5 is formed in a substantially rectangular plate shape as the basis of the light receiving device 4.

  The light receiving element 6 is a PDA (Photo Diode Array) provided on the base 5. The PDA is a detector having a property capable of measuring a plurality of interference fringes at a time. The light receiving element 6 is not limited to a PDA, and any detector such as a PSD (Position Sensitive Detector) or a CCD (Charge-Coupled Device) may be used.

The protection member 7 includes a plate surface 71 on one side contacting the plate surface 62 on the other side of the light receiving element 6 and a plate surface on the other side of the protection member 7 opposite to the plate surface 71 on the one side of the protection member 7. 72. The protection member 7 is formed in a substantially rectangular plate shape with glass which is a translucent material. On the entire side surface of the protection member 7, an area expansion portion 9 is provided that extends the contact area with the fixing member 8 beyond the total area of the side surface 60 of the light receiving element 6 and the side surface 70 of the protection member 7.
The plate surface 71 on one side and the plate surface 72 on the other side of the protection member 7 are smooth surfaces parallel to the plate surface having the scale 3 scale.

  The area expanding portion 9 is provided so that the area of the plate surface 72 on the other side is smaller than the plate surface 71 on the one side of the protection member 7. Specifically, the area expanding portion 9 is formed by chamfering the end or corner of the plate surface 72 on the other side of the protective member 7 with a file or the like.

The fixing member 8 is an adhesive that integrally fixes the base 5, the side surface 60 of the light receiving element 6, the side surface 70 of the protection member 7, and the area expanding portion 9. The fixing member 8 may be a transparent material resin or the like, and may fix the base 5, the side surface 60 of the light receiving element 6, the side surface 70 of the protection member 7, the area expanding portion 9, and the like. I can do it.
The frame body 10 is a plate-like member disposed so as to surround the side surface 60 of the light receiving element 6 and the side surface 70 of the protection member 7 so that the fixing member 8 does not flow on the base portion 5.

FIG. 2 is a diagram showing a manufacturing process of the light receiving device according to the first embodiment of the present invention.
Hereinafter, the manufacturing process of the light receiving device 4 will be described with reference to FIG.
As shown in FIG. 2A, first, the light receiving element 6 and the frame body 10 are installed on the base portion 5. At this time, the base 5 and the plate surface 61 on one side of the light receiving element 6 and the frame 10 are fixed with an adhesive or the like. The plate surface 61 and the frame body 10 on one side of the base 5 and the light receiving element 6 may be fixed without using an adhesive or the like, or may be installed in close contact with each other.

Next, as shown in FIG. 2B, a protective member 7 is placed in contact with the light receiving element 6 placed on the base 5. At this time, the light receiving element 6 is placed in close contact with the plate surface 62 on the other side and the plate surface 71 on the one side of the protection member 7 so as not to mix moisture, air, or the like. The plate surface 62 on the other side of the light receiving element 6 and the plate surface 71 on the one side of the protection member 7 may be fixed with an adhesive or the like.
Subsequently, as shown in FIG. 2C, the base 5, the light receiving element 6, the protection member 7, and the area expanding portion 9 are fixed using the fixing member 8. The frame body 10 may be removed after the fixing member 8 is solidified.

According to the present embodiment as described above, the following operations and effects can be achieved.
(1) The area expanding portion 9 can expand the contact area with the fixing member 8 rather than the total area of the side surface 60 of the light receiving element 6 and the side surface 70 of the protection member 7. And since the area expansion part 9 expands a contact area with the fixing member 8, the distance of the path | route to the light receiving element 6 can be lengthened. Therefore, the light receiving device 4 suppresses the peeling of the protective member 7 from the light receiving element 6 as compared with the case where the area expanding portion 9 is not provided, prevents intrusion of moisture, air, etc., and maintains reliability. Accuracy can be improved.

(2) Since the area expanding portion 9 is provided on the side surface 70 of the protection member 7, unevenness or rough surface due to the fixing member 8 is not formed on the incident surface of the light receiving device 4 on which light from the light source 2 is incident via the scale 3. Not formed. Therefore, the encoder 1 can achieve high accuracy.
(3) The area expanding portion 9 is provided over the entire side surface 70 of the protection member 7, thereby expanding the area in contact with the fixing member 8 rather than the total area of the side surface 60 of the light receiving element 6 and the side surface 70 of the protection member 7. can do. In addition, the area expanding portion 9 extends the contact area with the fixing member 8 even if a passage through which moisture, air, or the like enters is generated between the protection member 7 and the fixing member 8. The path distance up to 6 can be increased. Accordingly, the light receiving device 4 suppresses the passage of moisture, air, or the like from occurring between the protective member 7 and the fixing member 8, and further suppresses the protective member 7 from peeling off from the light receiving element 6. Can do.

(4) The area expanding portion 9 is configured such that the area of the plate surface 72 on the other side of the protection member 7 is smaller than the plate surface 71 on the one side of the protection member 7 that contacts the plate surface 62 on the other side of the light receiving element 6. Therefore, the protective member 7 and the light receiving element 6 are sandwiched between the fixing member 8 and the base portion 5 and can be strengthened against external force. Accordingly, the light receiving device 4 suppresses the passage of moisture, air, or the like from occurring between the protective member 7 and the fixing member 8, and further suppresses the protective member 7 from peeling off from the light receiving element 6. Can do.
(5) Since the encoder 1 includes the light receiving device 4 according to the present invention, it is possible to maintain reliability in measurement and improve measurement accuracy.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.
In the following description, parts that have already been described are assigned the same reference numerals and description thereof is omitted.

FIG. 3 is a cross-sectional view showing an encoder including a light receiving device according to the second embodiment of the present invention.
In the first embodiment, the protective member 7 in the light receiving device 4 of the encoder 1 is made of glass.
The protective member 7A in the light receiving device 4A of the encoder 1A of the present embodiment is different from the protective member 7 of the first embodiment in that the protective member 7A is formed of a plastic that is a translucent material.
The protective member 7A can be easily processed by being formed of plastic as compared with the case of being formed of glass.

In the said 1st Embodiment, the area expansion part 9 of the protection member 7 was formed by chamfering the edge part and corner | angular part of the plate surface 72 of the other side of the protection member 7 with a file.
As shown in FIG. 3, the area expanding portion 9A of the protective member 7A of the present embodiment is such that the area of the plate surface 72A on the other side of the protective member 7A is smaller than the plate surface 71A on the one side of the protective member 7A. This is different from the area expanding portion 9 of the first embodiment in that it has a substantially trapezoidal cross section.

  The area expanding portion 9A is formed in a substantially trapezoidal cross section over the entire side surface 70A of the protective member 7A, so that the contact area between the protective member 7A and the fixing member 8 can be expanded. Further, the area expanding portion 9A expands the contact area with the fixing member 8 even if a passage through which moisture, air, or the like enters is generated between the protective member 7A and the fixing member 8, and the light receiving element 6 Since the distance to the passage can be increased, the intrusion of moisture, air, or the like can be suppressed.

Also in this embodiment, in addition to the same operations and effects as (1) to (5) in the first embodiment, the following operations and effects can be achieved.
(6) The area expanding portion 9A of the protective member 7A is formed in a substantially trapezoidal cross section so that the contact area between the fixing member 8 and the protective member 7A is expanded, and the protective member 7A is peeled off from the light receiving element 6. Can be suppressed.

[Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.
In the following description, parts that have already been described are assigned the same reference numerals and description thereof is omitted.

FIG. 4 is a cross-sectional view showing an encoder provided with a light receiving device according to a third embodiment of the present invention.
In the second embodiment, the area expanding portion 9A of the protective member 7A in the light receiving device 4A of the encoder 1A has a smaller area of the plate surface 72A on the other side of the protective member 7A than the plate surface 71A on the one side of the protective member 7A. As a result, the cross section was formed in a substantially trapezoidal shape.
In the light receiving device 4B of the encoder 1B of the present embodiment, the area expanding portion 9B of the protective member 7B has a smaller area of the plate surface 72B of the protective member 7B than the plate surface 71B of the protective member 7B, as shown in FIG. Moreover, it is different from the area expanding portion 9A of the second embodiment in that it is formed in a substantially stepped cross section.

  The area expanding portion 9B is formed in a substantially stepped cross section over the entire side surface 70B of the protective member 7B, so that the contact area between the protective member 7B and the fixing member 8 can be expanded. Moreover, even if the passage where moisture, air, or the like enters is generated between the protective member 7B and the fixing member 8, the area expanding portion 9B extends the contact area with the fixing member 8 and the light receiving element 6 Since the distance to the passage can be increased, the intrusion of moisture, air, or the like can be suppressed.

Also in this embodiment, in addition to the same operations and effects as (1) to (5) in the first embodiment, the following operations and effects can be achieved.
(7) The area expanding portion 9B of the protective member 7B is formed in a substantially stepped cross section, thereby expanding the contact area between the fixing member 8 and the protective member 7B, and the protective member 7B is peeled off from the light receiving element 6. Can be suppressed.

[Fourth Embodiment]
Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings.
In the following description, parts that have already been described are assigned the same reference numerals and description thereof is omitted.

FIG. 5 is a cross-sectional view showing an encoder including a light receiving device according to a fourth embodiment of the present invention.
In the third embodiment, the area expanding portion 9B of the protection member 7B in the light receiving device 4B of the encoder 1B has a smaller area of the plate surface 72B on the other side of the protection member 7B than the plate surface 71B on the one side of the protection member 7B. Thus, the cross section was formed in a substantially stepped shape.
In the light receiving device 4C of the encoder 1C of the present embodiment, the area expanding portion 9C of the protective member 7C includes a plate surface 71C on one side of the protective member 7C and a plate surface 72C on the other side of the protective member 7C, as shown in FIG. This is different from the area expanding portion 9B of the third embodiment in that it is formed in a substantially letter-shaped cross section so as to have an area of almost the same size, and is processed into a rough surface.

  The area expanding portion 9C is processed by roughening with, for example, sandblasting or sanding. The area expanding portion 9C can expand the contact area between the protective member 7C and the fixing member 8 by making the entire side surface 70C of the protective member 7C rough. Further, the area expanding portion 9C expands the contact area with the fixing member 8 even if a passage through which moisture, air or the like enters is generated between the protective member 7C and the fixing member 8, and the light receiving element 6 Since the distance to the passage can be increased, the intrusion of moisture, air, or the like can be suppressed.

Also in this embodiment, in addition to the same operations and effects as (1) to (5) in the first embodiment, the following operations and effects can be achieved.
(8) The area expanding portion 9C of the protective member 7C is formed on a rough surface, thereby expanding the contact area between the fixing member 8 and the protective member 7C and suppressing the protective member 7C from peeling off from the light receiving element 6. can do.
(9) Since the area expanding portion 9C is a rough surface, it can be easily processed.

[Modification of Embodiment]
The present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in each of the above embodiments, the case where the light receiving devices 4 and 4A to 4C according to the present invention are used for the encoder 1 has been described. However, the light receiving devices 4 and 4A to 4C can be used in other measuring devices. There is no particular limitation on what to implement.

  In each said embodiment, although the area expansion parts 9, 9A-9C were formed in the whole surface 70, 70A-70C of the protection members 7, 7A-7C, the side surface 70 of the protection members 7, 7A-7C , 70A to 70C, or may be formed across the plate surfaces 72 and 72A to 72C of the protective members 7 and 7A to 7C. Moreover, in the said 1st Embodiment-3rd Embodiment, although the area expansion parts 9, 9A, 9B were not processed into the rough surface, you may be processed into the rough surface.

  In the first embodiment to the third embodiment, the area expanding portions 9, 9A, 9B of the protection members 7, 7A, 7B are the plate surfaces 71, 71A on one side of the protection members 7, 7A, 7B. Although the area of the plate surfaces 72, 72A, 72B on the other side of the protective members 7, 7A, 7B is smaller than 71B, the area expansion portion protects more than the plate surface on one side of the protective member. The area of the plate surface on the other side of the member may not be formed so as to be small. For example, the area expansion portion may be formed such that the area of the plate surface on the other side of the protection member is larger than the plate surface on the one side of the protection member, or the plate surface on one side of the protection member and the protection You may form so that the area of the plate | board surface of the other side of a member may become the substantially same magnitude | size.

FIG. 6 is a cross-sectional view showing a light receiving device according to a modification of the present invention.
In each said embodiment, although the fixing member 8 was provided without contacting the plate | board surfaces 72 and 72A-72C of the other side of the protection members 7 and 7A-7C, as shown to FIG. 6 (A). When the other plate surface 72D of the protection member 7D of the light receiving device 4D is the area expanding portion 9D, the fixing member 8 may be provided so as to cover the entire surface of the other plate surface 72D of the protection member 7D. Good. With such a configuration, the area expanding portion 9D can expand the contact area with the fixing member 8 rather than the total area of the side surface 60 of the light receiving element 6 and the side surface 70D of the protection member 7D.

Further, the fixing member 8 can be sealed to fix the protective member 7D by fixing the base member 5, the light receiving element 6, and the plate surface 72D on the other side of the protective member 7D.
Therefore, the light receiving device 4D suppresses the passage of moisture, air, or the like from occurring between the protective member 7D and the fixing member 8, and suppresses the protective member 7D from peeling from the light receiving element 6. it can.

Further, as shown in FIG. 6B, when the other side plate surface 72E of the protection member 7E of the light receiving device 4E is used as the area expanding portion 9E, a part of the other side plate surface 72E of the protection member 7E is covered. As described above, the fixing member 8 may be provided in a range that does not hinder the incidence of light on the incident surface of the light receiving device 4E.
With such a configuration, the area expanding portion 9E can expand the contact area with the fixing member 8 rather than the total area of the side surface 60 of the light receiving element 6 and the side surface 70E of the protective member 7E.
In other words, the area expanding portion only needs to be able to expand the contact area with the fixed member rather than the total area of the side surfaces of the light receiving element and the protective member.

  In the first embodiment, the protective member 7 is made of glass, and in the second to fourth embodiments, the protective members 7A to 7C are made of plastic. Any material may be used as long as it is formed of.

  As described above, it can be suitably used for a light receiving device that can suppress the peeling of the protective member from the light receiving element to maintain reliability and achieve high accuracy.

DESCRIPTION OF SYMBOLS 1,1A-1C Encoder 2 Light source 3 Scale 4, 4A-4E Light-receiving device 5 Base 6 Light-receiving element 7, 7A-7E Protection member 8 Fixing member 9, 9A-9E Area expansion part 60 Light-receiving element side surface 70 Side surface of protection member

Claims (5)

A light receiving element having a base, a plate surface on one side contacting the base and receiving light, and a plate surface contacting the plate on the other side of the light receiving element; A plate-shaped protection member for protecting the light receiving device, and a fixing member for fixing the protection member to the light receiving element,
An area expanding portion that expands a contact area with the fixing member more than a total area of a side surface of the light receiving element and a side surface of the protection member;
The fixing member is
A light receiving device, wherein the light receiving device is fixed over the base, the side surface of the light receiving element, the side surface of the protective member, and the area expanding portion. The light receiving device according to claim 1,
The area expansion part is
A light receiving device provided on a side surface of the protection member. In the light receiving device according to claim 2,
The area expansion part is
A light receiving device provided on the entire side surface of the protective member. In the light receiving device according to claim 2 or 3,
The area expansion part is
The area of the plate surface on the other side of the protective member opposite to the plate surface on the one side of the protective member is smaller than the plate surface on the one side of the protective member contacting the plate surface on the other side of the light receiving element. It is provided so that it may become. A light source that emits light;
A scale irradiated with light from the light source;
5. A photoelectric encoder comprising: the light receiving device according to claim 1, which receives light from the light source through the scale.

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