Patent Description:
As a photoelectric sensor configured to detect whether there is an object, there is a small photoelectric sensor that is miniaturized so that it can cope with various detection environments and installation places. For example, in the following Patent Document <NUM>, a retroreflective type photoelectric sensor in which light projecting units and light receiving units are disposed in parallel, and light is projected toward a reflection plate installed to face the light projecting and receiving units with a detection region therebetween is disclosed.

[Patent Document <NUM>] <CIT>
<CIT> describes a photoelectric sensor which includes a casing, a lens member, a transmissive plate, a light projecting and receiving circuit board on which a light projecting element and a light receiving element are mounted, a display and operation unit, a displaying transmissive member, various brackets, a cable, a bush, and a fixing member. <CIT> relates to a photoelectronic sensor which houses a light projection section, a light reception section, a polarization filter for permeating only a vertical polarization component in a light projection direction of the light projection section, and a polarization filter for permeating only a horizontal polarization component in a light reception direction of the light reception section in a housing. The housing has a rectangular parallelepiped shaped box body formed of a member such as resin having non-light transmissivity, and an opening is formed on a front face of the housing. <CIT> discloses an optical pickup unit comprising an objective lens that focusses laser light on an optical disc, a lens holder that holds the objective lens, a coil that is fitted on the lens holder and capable of driving the lens holder, and a reinforcement member that is fitted on the lens holder and reinforces strength of the lens holder. <CIT> discloses a composite type light sensor comprising a sensor portion molded into a light-transmitting resin together with light receiving elements and a case portion mounted with light receiving means such as a lens for receiving the sensor portion.

A small photoelectric sensor includes optical components such as a light projecting unit and a light receiving unit, and the optical components are held by a holder. Here, in the holder, an opening through which light is projected and received by optical components is provided, and the opening is sealed by a cover lens. Here, the cover lens may be a low-distortion plate-like lens according to optical requirements and may be connected to the holder on the plane. In such a case, the cover lens is disposed so that it overlaps an edge that defines the opening of the holder and may be connected to the edge by laser welding, ultrasonic welding, or the like.

However, if the outer shape of the holder is made smaller in order to make the photoelectric sensor smaller, a capacity for accommodating optical components (in other words, a volume of a space for accommodating optical components) is also reduced, and there is a limitation on the size of the optical components that can be accommodated. Here, it is conceivable to narrow the width of the edge that defines the opening so that the capacity for accommodating optical components increases. However, when a sufficient width of the edge is not secured, there is a risk of insufficient connection between the cover lens and the holder, and it becomes difficult to secure sealing properties.

Thus, an objective of the disclosure is to provide a small photoelectric sensor that can secure a capacity for accommodating an optical component and securing sealing properties. A small photoelectric sensor according to the present invention is characterized by the features of claim <NUM>. Preferred embodiments of the invention are defined by the subclaims.

A small photoelectric sensor according to the present invention includes a holder in which an opening, an edge that defines the opening, and four fixing parts that are independently provided at four corners of a front surface are formed on the front surface; a cover lens that is provided at a position interposed between the four fixing parts, and is connected to the edge in a region overlapping the edge; and an optical component that is held by the holder and projects or receives light through the opening.

According to this aspect, when the small photoelectric sensor includes four fixing parts independently provided at the four corners of the front surface of the holder, the edge is not surrounded by the fixing parts, the edge is provided on the outer circumference of the front surface of the holder, and the opening can be widened. Therefore, compared to the small photoelectric sensor of the related art, it is possible to increase a capacity for accommodating optical components while maintaining a small outer shape of the small photoelectric sensor. In addition, since the opening can be widened without narrowing the width of the edge, it is possible to secure the capacity for accommodating optical components, it is possible to reliably connect the holder and the cover lens, and it is possible to secure sealing properties.

In the above aspect, the four fixing parts may be provided outside a region in which the cover lens and the edge overlap, and four corners of the cover lens may be fixed with the four fixing parts.

According to this aspect, it is possible to fix the cover lens with a simple configuration without separately providing a component for fixing the cover lens to the holder or the like.

In the above aspect, the front surface of the holder may have a substantially rectangular shape, and the cover lens may have a substantially octagonal shape in which four corners in contact with the four fixing parts are chamfered.

According to this aspect, since the outer shape of the space for accommodating optical components can be formed into a polygonal shape, compared to the small photoelectric sensor of the related art having a substantially circular outer shape, rectangular circuit components and substrates can be efficiently accommodated in the holder.

According to the present invention, the holder is made of a resin. The holder and the cover lens are connected by laser welding without using an adhesive.

Accordingly, when the holder is made of a resin, even if the holder is made smaller so that it is suitable for a small photoelectric sensor, it is possible to easily form a fine structure.

According to the disclosure, when the cover lens is fixed with four fixing parts independently provided at four corners of the front surface of the holder, it is possible to provide a small photoelectric sensor that can secure a capacity for accommodating an optical component and securing sealing properties.

Exemplary embodiments of the disclosure will be described with reference to the appended drawings. Here, in the drawings, the same reference numerals are used to denote the same or similar components.

<FIG> is an exploded perspective view showing a small photoelectric sensor <NUM> of the related art. The small photoelectric sensor <NUM> includes a cover lens <NUM>, an optical component (not shown), and a holder <NUM>. The small photoelectric sensor <NUM> accommodates an optical component inside the holder <NUM>, and is assembled by attaching the cover lens <NUM> to the holder <NUM>.

The cover lens <NUM> is connected to the holder <NUM> so that it covers an opening <NUM> of the holder <NUM>. Specifically, the cover lens <NUM> that is fitted into an edge <NUM> which defines the opening <NUM> of the holder <NUM>, and positioned by a fixing part <NUM> is connected to the holder <NUM> using laser welding, ultrasonic welding, or the like (hereinafter referred to as "laser welding or the like").

The optical component is a component of an optical system that projects light or receives light to or from an object to be detected. For example, the optical component is constituted by a light projecting unit including a light projecting element and a light projecting lens and a light receiving unit including a light receiving element and a light receiving lens.

In the holder <NUM>, the opening <NUM> allowing light projected from an optical component to pass therethrough and introducing light reflected from a detection object, a reflection plate, or the like into the holder, the edge <NUM> that defines the opening <NUM> and connects the holder <NUM> and the cover lens <NUM>, and the fixing part <NUM> for positioning the cover lens <NUM> are formed on the front surface.

<FIG> is a perspective view showing a state in which the cover lens <NUM> of the small photoelectric sensor <NUM> of the related art is attached to the holder <NUM>. The fixing part <NUM> is formed to surround and fix the entire outer circumference of the cover lens <NUM> when the cover lens <NUM> is fitted into the fixing part <NUM>. In addition, the edge <NUM> is formed to overlap an outer circumferential part of the cover lens <NUM> when the cover lens <NUM> is fitted into the fixing part <NUM> and placed on the edge <NUM>. In the small photoelectric sensor <NUM>, while the cover lens <NUM> is positioned with the fixing part <NUM>, the edge <NUM> and the cover lens <NUM> are connected by laser welding or the like, and thus the optical component accommodated in the holder <NUM> is sealed.

In the small photoelectric sensor <NUM> of the related art, the edge <NUM> is provided to surround the opening <NUM> of the holder <NUM>, and the fixing part <NUM> is provided to surround the edge <NUM>. Therefore, when the outer shape of the holder <NUM> is made smaller while maintaining the width of the edge <NUM>, the capacity for accommodating optical components is reduced.

An overall configuration of a small photoelectric sensor <NUM> according to the present embodiment will be described with reference to <FIG> is a perspective view showing an exterior of the small photoelectric sensor <NUM> according to the present embodiment during use. For convenience of explanation, the front, back, left, right, up and down are based on those shown in <FIG> and <FIG>.

The small photoelectric sensor <NUM> is a sensor for detecting whether there is an object or the like according to projection or reception of light. The small photoelectric sensor <NUM>, for example, includes a housing <NUM> as shown in <FIG>.

The housing <NUM> is made of, for example, a resin or a metal, and has a substantially rectangular parallelepiped shape. Inside the housing <NUM>, an optical component (not shown) and a holder <NUM> for holding the optical component are accommodated. In addition, on the outer surface of the housing <NUM>, an indicating lamp 5a and an indicating lamp 5b for displaying an operation state of the small photoelectric sensor <NUM> (hereinafter collectively referred to as "indicating lamps <NUM>") are provided. The operation state includes, for example, a power supply state and a detection state of the small photoelectric sensor <NUM>, but any state may be included according to applications of the small photoelectric sensor <NUM>. The indicating lamp <NUM> may include, for example, a light emitting element such as an LED element.

On the front surface of the housing <NUM>, an opening (not shown) for allowing light projected or received to pass therethrough is provided. A cover lens <NUM> covering the opening, four fixing parts 12a, 12b, 12c, and 12d (hereinafter collectively referred to as "fixing parts <NUM>") for fixing the cover lens <NUM> at four corners, and the like are fitted. In such a configuration, the small photoelectric sensor <NUM> emits light from the optical component accommodated in the housing <NUM> through the cover lens <NUM>, and allows light to enter the optical component through the cover lens <NUM>, and detects whether there is an object or the like.

Next, the configurations of the holder <NUM>, the optical component, and the cover lens <NUM> (hereinafter these components are collectively referred to as "internal components <NUM>") which are main constituent components accommodated inside the housing <NUM> will be described with reference to <FIG> and <FIG>. <FIG> is a perspective view showing an exterior of the internal components <NUM> excluding the optical component during use. <FIG> is an exploded perspective view showing the internal components <NUM> excluding the optical component.

The holder <NUM> is a component for holding an optical component. The holder <NUM> is formed to include an opening <NUM>, an edge <NUM>, and the fixing part <NUM>. The holder <NUM> may have, for example, a substantially rectangular parallelepiped shape. Here, the fact that the holder <NUM> has a "substantially rectangular parallelepiped shape" may refer to having a shape having a surface other than six surfaces constituting a rectangular parallelepiped shape, a shape with interior angles that are not all <NUM> degrees, or a shape that is different from a strict rectangular parallelepiped shape. In addition, a front surface of the holder <NUM> may have, for example, a substantially rectangular shape. Here, the "front surface" is a surface that faces an object to be detected or a reflection plate in the small photoelectric sensor <NUM> and the internal components <NUM>, and projects and receives light from the front surface.

In addition, the holder <NUM> is made of a resin, and made of, specifically, PBT, PC, ABS, PMMA, PAR, or the like. In addition, the holder <NUM> may be made of a thermoplastic resin, and may be formed by filling a resin into a mold. When the holder <NUM> is made of a resin, even if the holder <NUM> is made smaller so that it is suitable for the small photoelectric sensor <NUM>, it is possible to easily form a fine structure. In addition, when the holder <NUM> is made of a resin, the holder <NUM> and the cover lens <NUM> can be connected by laser welding or the like without using an adhesive.

Four fixing parts <NUM> are independently provided at four corners of the front surface of the holder <NUM> and position the cover lens <NUM>. The fixing part <NUM> may be provided outside a region in which the cover lens <NUM> and the edge <NUM> overlap. In addition, the fixing parts <NUM> are ribs provided at the four corners of the front surface of the holder <NUM>. Here, the "rib" is a component protruding to the front surface with respect to other components such as the edge <NUM>. When the fixing parts <NUM> are ribs, the cover lens <NUM> is fitted and fixed between the ribs. In such a configuration, it is possible to fix the cover lens <NUM> with a simple configuration without separately providing a component for fixing the cover lens <NUM> or the like.

When the fixing part <NUM> is a rib, the height of the rib (the length of a part that protrudes from the front surface) may be substantially the same as the thickness of the cover lens <NUM>. For example, when the height of the rib and the thickness of the cover lens <NUM> vary, a step is generated, and in a state in which the small photoelectric sensor <NUM> shown in <FIG> is used, dirt is likely to accumulate in the step, and it is difficult to remove dirt adhered to the cover lens <NUM> due to the step. When the height of the fixing part <NUM> and the thickness of the cover lens <NUM> are set to be substantially the same, it is possible to provide the small photoelectric sensor <NUM> that is unlikely to become dirty and in which dirt is easily removed.

The opening <NUM> is formed on the front surface of the holder <NUM>, and allows light projected from an optical component to pass therethrough, and introduces light such as light reflected from a detection object or a reflection plate and the like into the holder <NUM>. The opening <NUM> may have a polygonal shape, and has an outer shape with a substantially octagonal shape in the present embodiment. Here, the opening <NUM> may have an elliptical shape or a rounded rectangular shape.

The edge <NUM> defines the opening <NUM>, and becomes a region connecting the cover lens <NUM> and the holder <NUM>. When the cover lens <NUM> and the holder <NUM> at the edge <NUM> are connected, the optical component held by the holder <NUM> is sealed. A width W of the edge <NUM> is a sealing margin for sealing the holder <NUM> and the cover lens <NUM>. The width W may be constant along the edge <NUM>.

The optical component (not shown) is a component of an optical system that projects or receives light to or from an object to be detected. For example, the optical component is constituted by a light projecting unit including a light projecting element and a light projecting lens and a light receiving unit including a light receiving element and a light receiving lens. The optical component is assembled and held in the holder <NUM>.

The cover lens <NUM> is, for example, a component such as a plate-like lens. The cover lens <NUM> is provided at a position interposed between four fixing parts <NUM>, and is connected to the edge <NUM> in a region overlapping the edge <NUM>. The cover lens <NUM> is fixed at four corners with four fixing parts <NUM>, and covers the opening <NUM> of the holder <NUM>. The cover lens <NUM> is made of a translucent material and can project or receive light from an optical component. For example, in the cover lens <NUM>, an outer circumferential part indicated by a dotted line shown in <FIG> and a solid line showing an outer edge of the cover lens <NUM> as an area <NUM> overlapping the edge <NUM> is connected to the edge <NUM> in the overlapping area <NUM> by laser welding or the like.

For example, when the front surface of the holder <NUM> has a substantially rectangular shape, a surface covering the opening <NUM> of the cover lens <NUM> may have a shape that substantially matches a shape in which four corners at which the fixing parts <NUM> are provided are chamfered. That is, the cover lens <NUM> may have a substantially octagonal shape in which four corners in contact with the four fixing parts <NUM> are chamfered. In this case, the outer shape of the edge <NUM> and the outer shape of the cover lens <NUM> substantially match. In such a configuration, since the outer shape of the space for accommodating optical components can be formed into a polygonal shape, compared to the small photoelectric sensor <NUM> of the related art having a substantially circular outer shape, rectangular circuit components and substrates can be efficiently accommodated in the holder <NUM>.

Claim 1:
A small photoelectric sensor (<NUM>), comprising:
a holder (<NUM>) in which an opening (<NUM>), an edge (<NUM>) that defines the opening (<NUM>), and four fixing parts (<NUM>, 12a, 12b, 12c, 12d) that are independently provided at four corners of a front surface of the holder (<NUM>) are formed on the front surface, wherein the four fixing parts (<NUM>, 12a, 12b, 12c, 12d) are provided as ribs protruding from the front surface of the holder (<NUM>);
a cover lens (<NUM>) that is provided at a position interposed between the four fixing parts (<NUM>, 12a, 12b, 12c, 12d), and is connected to the edge (<NUM>) in a region overlapping the edge (<NUM>), wherein a height of each of the ribs is the same as a thickness of the cover lens (<NUM>); and
an optical component that is held by the holder (<NUM>) and projects or receives light through the opening (<NUM>),
wherein the holder (<NUM>) is made of a resin,
and the holder (<NUM>) and the cover lens (<NUM>) are connected by laser welding without using an adhesive.