JP2005051163A - Optical unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact optical unit which eliminates the necessity of adjustment in assembly. <P>SOLUTION: In an optical unit 1, a die pad 3 is fixed to the inside of a package 2, and a first cavity 7 and a second cavity 8 are formed therein. A light emitting element 4 is mounted on one side of the die pad 3, and a photosensitive element 5 is mounted on the other side thereof. In the package 2, an aperture 10 which light passes through, a lens holding part 11 holding a projection lens 12, a mirror holding part 14 holding a reflection mirror 15, and a window part 17 holding a condenser lens 18, are formed integrally. An optical component constituting the optical unit 1 is fixed directly to the package 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical unit in which light emitting means and light receiving means are accommodated in a single package. Specifically, the inside of the package is partitioned by a die pad, the light emitting means is mounted on one surface of the die pad, the light receiving means is mounted on the other surface, and the holding part for the optical components constituting the optical unit is formed integrally with the package. This reduces the size of the unit and eliminates the need for adjustment during assembly.

  An optical unit including a light emitting element and a light receiving element is used as an optical sensor for detecting the presence or absence of an object to be detected. In the conventional optical sensor, each optical component such as a light emitting element and a light receiving element is configured by an independent package, and a housing structure is required in which these components are further assembled and coupled while adjusting the optical axis. .

  As an example of an independent package structure of optical components, the light emitting element is generally in the form of a can type package, and the light receiving element is generally in the form of a photodiode encapsulated in a resin package with leads. In addition, in a configuration using a light projection lens to collect the light emitted from the light emitting element, three-dimensional position adjustment is required for adjusting the distance between the light emitting element and the lens and adjusting the optical axis. There are many things.

  7A and 7B are perspective views showing a configuration example of a conventional light-emitting element. FIG. 7A shows an external appearance, and FIG. 7B shows an internal configuration. The light emitting device 100 includes a semiconductor laser 101 as shown in FIG. The semiconductor laser 101 is attached to the mount 102, and the mount 102 is attached to the eyelet 103. A lead 104 is attached to the eyelet 103, and a land 105 connected to the lead 104 and the semiconductor laser 101 are electrically connected by a wire 106.

  A cap 107 is attached to the eyelet 103 as shown in FIG. 7A to protect the semiconductor laser 101. The cap 107 is provided with a window 107a made of transparent glass or the like, and laser light from the semiconductor laser 101 is emitted from the window 107a.

  FIG. 8 is a cross-sectional view showing an example of a conventional structure for mounting each optical component, and a conventional structure for mounting a light emitting element and a light projecting lens will be described. An attachment hole 111 is provided in the fixing member 110, and the light emitting element 100 described with reference to FIG. The inner diameter of the mounting hole 111 is set larger than the outer diameter of the cap 107 of the light emitting element 100 and smaller than the outer diameter of the eyelet 103. Accordingly, when the cap 107 is inserted into the attachment hole 111 and the light emitting element 100 is attached to the fixing member 110, the cap 107 can move within the attachment hole 111, thereby adjusting the position of the light emitting element 100 in the X axis direction and the Y axis direction. Can be done.

  The light projecting lens 112 is housed in the outer cylinder 113, and the outer cylinder 113 is inserted into the attachment hole 111 and attached to the fixing member 110. The light projecting lens 112 is attached to the outer cylinder 113 by a fixing member 114, and the outer cylinder 113 is provided with an aperture 115 through which laser light passes. The outer diameter of the outer cylinder 113 is substantially the same as the inner diameter of the mounting hole 111. Accordingly, when the outer tube 113 is inserted into the mounting hole 111 and the light projecting lens 112 is attached to the fixing member 110, the position of the light projecting lens 112 in the Z-axis direction can be adjusted.

  In the above configuration, while the light emitting element 100 emits light, the light emitting element 110 is moved in the X axis direction and the Y axis direction to adjust the optical axis, and the outer cylinder 113 that holds the light projecting lens 112 is moved in the Z axis direction. The focus position is adjusted by moving the light emitting element 100 and the outer cylinder 113 to the fixing member 110 after the position adjustment.

  On the other hand, an optical unit in which a light emitting element and a light receiving element are mounted in a single package has also been proposed. For example, a light emitting element and a light receiving element are provided in parallel on the surface of the substrate, and the light emitting element and the light receiving element are integrated with a resin mold so that the light emitting element and the light receiving element are mounted in a single package (for example, , See Patent Document 1).

JP 2000-244409 A.

  In the optical unit in which the light emitting element and the light receiving element are housed in independent packages, there is a problem that adjustment of the optical axis is necessary when mounting each package, and there are many adjustment items. Further, there is a problem that a member for holding each optical component is necessary and the number of components increases, leading to an increase in cost. Furthermore, there is a problem that the size of the optical unit is increased.

  In addition, even with an optical component in which a light-emitting element and a light-receiving element are mounted in a single package, the configuration in which the light-emitting element and the light-receiving element are arranged in parallel cannot reduce the size of the optical component so much, and there are restrictions on the place where it can be installed There arises a problem that the use is limited.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a small optical unit that does not require adjustment during assembly.

  In order to solve the above-described problems, an optical unit according to the present invention forms a first cavity and a second cavity by partitioning the inside of a package containing a light emitting means and a light receiving means, and a first cavity. The light emitting means is mounted on the cavity side surface, the die pad on which the light receiving means is mounted on the second cavity side surface, and one wall portion of the package constituting the first cavity, and emitted from the light emitting means. The first opening through which light passes, the second opening through which the light incident on the light receiving means passes, and the light emitted from the light emitting means are provided on the other walls of the package constituting the second cavity. A light projecting means for condensing light, a light projecting means holding portion to which the light projecting means is attached, and a light projecting means holding portion formed integrally with the light emitting means and the first opening; and Change direction An optical path changing means, an optical path changing means holding part formed integrally with the package, to which the optical path changing means is attached, and a condensing means attached to the second opening for collecting light from the outside. It is a thing.

  According to the optical unit of the present invention, the light emitted from the light emitting means passes through the light projecting means and the first opening, and the light path is changed by the light path changing means and emitted to the outside of the optical unit. For example, when the light emitted from the optical unit irradiates the object to be detected, the light reflected by the object to be detected returns to the direction of the optical unit, is condensed by the light collecting means, and enters the light receiving means.

  In the optical unit according to the present invention, by attaching the optical path changing means to the package, the reflected light of the light emitted from the light emitting means mounted on one surface of the die pad is transmitted to the light receiving means mounted on the other surface of the die pad. Can be incident.

  In the optical unit of the present invention, the light emitting means is mounted on one surface of the die pad, the light receiving means is mounted on the other surface, and the die pad is attached to the package. Less space is required. In addition, since the holding parts of the optical parts constituting the optical unit such as the light projecting means and the optical path changing means are integrally formed in the package, a separate member for holding the optical parts is unnecessary, and the number of parts is reduced. It can be greatly reduced. Therefore, the optical unit can be reduced in size and the cost can be reduced.

  Furthermore, since each optical component is directly attached to the package, the mounting accuracy of each optical component is high, and adjustment such as matching the optical axes between the optical components is not necessary. Therefore, no adjustment can be achieved during assembly of the optical unit.

  In addition, the interior of the package is partitioned by a die pad to form a first cavity in which the light emitting means is mounted and a second cavity in which the light receiving element is mounted, so that light emitted from the light emitting means is directly transmitted to the light receiving means in the package. There is no incident. Therefore, the performance can be improved with a simple configuration.

  Hereinafter, embodiments of the optical unit of the present invention will be described with reference to the drawings. 1 to 4 show configuration examples of the optical unit according to the present embodiment. FIG. 1 is a side sectional view, FIG. 2 is a plan view, FIG. 3 is a bottom view, and FIG. Here, although the cut surface in FIG. 1 is the AA line shown in FIG. 2, only the package mentioned later is shown in the cross section. FIG. 2 is a plan view of the optical unit 1 as viewed from the direction of arrow B in FIG. 1, but shows a state in which a cover (to be described later) is not attached to show the internal configuration.

  The optical unit 1 according to the present embodiment includes a light emitting element 4 on one surface of a die pad 3 attached to a package 2, a light receiving element 5 on the other surface, and directly attaches various optical components to the package 2. It is what.

  The package 2 is configured by molding, and each holding portion and the like described later are integrally formed. As an example, the package 2 can be realized with a length in the long side direction of about 6 to 7 mm, a length in the short side direction of about 3 to 4 mm, and a height of about 2 to 3 mm. The die pad 3 and the plurality of leads 6 are composed of a lead frame (not shown) and are formed integrally with the package 2. The lead 6 protrudes from the outer surface of one side wall portion of the package 2.

  As shown in FIG. 1, the die pad 3 is provided so as to partition a part of the inside of the package 2 in the height direction. As a result, the first cavity 7 is formed on one surface side of the die pad 3 surrounded by the wall portion of the package 2 inside the package 2, and the second cavity 8 is formed on the other surface side of the die pad 3. It is formed. A structure for light emission is provided on the first cavity 7 side, and a structure for light reception is provided on the second cavity 8 side.

  Next, the configuration on the light emission side in the optical unit 1 will be described. The light emitting element 4 is an example of a light emitting means, for example, a laser diode and a laser on photodiode (LOP) composed of a PIN photodiode as a light receiving means for monitoring the light emission amount of the laser and keeping the light emission power constant. is there. The light emitting element 4 is mounted on one surface of the die pad 3 facing the first cavity 7 using a silver paste or the like.

  The first cavity 7 is provided with a land portion 6 a electrically connected to a predetermined lead 6, and the laser diode and the photodiode constituting the light emitting element 4 are electrically connected to the land portion 6 a by a wire 9. The Here, the light irradiation direction of the light emitting element 4 is substantially parallel to the surface of the die pad 3.

  The first cavity 7 includes an aperture 10 as a first opening. The aperture 10 is provided in a front wall portion that is one wall portion of the package 2 that constitutes the first cavity 7, and is an opening having a predetermined shape for narrowing the light emitted from the light emitting element 4. It is located on the optical axis of the light emitted from. The light emitted from the light emitting element 4 passes through the aperture 10 and becomes a beam narrowed to a desired shape. The aperture 10 is formed when the package 2 is molded.

  The first cavity 7 includes a lens holding portion 11 between the die pad 3 and the aperture 10. The lens holding unit 11 is an example of a light projecting unit holding unit, and a light projecting lens 12 serving as a light projecting unit that collects light emitted from the light emitting element 4 is attached to the lens holding unit 11.

  The light projecting lens 12 is a spherical ball lens, and the lens holding portion 11 is formed by forming a hole having a diameter smaller than the diameter of the light projecting lens 12 when the package 2 is molded. The projection lens 12 is placed on the lens holding portion 11 and fixed using an adhesive such as a UV curable resin.

  Thereby, the light projection lens 12 when the light projection lens 12 is attached to the lens holding portion 11 from the relationship between the diameter of the light projection lens 12, the position where the lens holding portion 11 is provided, and the diameter of the lens holding portion 11. The position of the center in the three-dimensional direction is uniquely determined.

  Then, the shape such as the diameter and height of the lens holding portion 11 is set so that the light projection lens 12 is attached at a position where the optical axis of the light emitted from the light emitting element 4 coincides with the center of the light projection lens 12. The In addition, since the focal point is determined by the distance between the light emitting point of the light emitting element 4 and the light projecting lens 12, the lens holding unit is attached so that the light projecting lens 12 is attached at a position where a predetermined desired focal distance is obtained. 11 positions are set.

  The hole constituting the lens holding portion 11 does not penetrate to the second cavity 8. Thereby, the light emitted from the light emitting element 4 does not leak directly into the second cavity 8 inside the package 2.

  The light projecting lens 12 may be other than a ball lens, but by using a ball lens, the light projecting lens 12 can be attached at a predetermined position without considering the orientation at the time of attachment. Moreover, the shape of the lens holding part 11 is an example.

  The first cavity 7 has an opening at a portion facing one surface of the die pad 3, and after mounting the light projecting lens 12 and the like, a cover 13 is attached to the opening and sealed.

  The package 2 includes a mirror holding unit 14. The mirror holding unit 14 is an example of an optical path changing unit holding unit, and a reflection mirror 15 as an optical path changing unit that changes the optical path of the light emitted from the light emitting element 4 is attached to the mirror holding unit 14.

  The mirror holding portion 14 has a shape protruding from the wall portion on the front side of the package 2 and is integrally formed when the package 2 is molded. By fixing the reflection mirror 15 to the mirror holding portion 14, the reflection mirror 15 is fixed at a constant angle. The reflecting mirror 15 is attached to a position where the reflecting surface faces the aperture 10 and light passing through the aperture 10 is irradiated.

  An irradiation port 16 is provided on the bottom surface of the package 2. The irradiation port 16 is an opening facing the reflection surface of the reflection mirror 15. Therefore, the light emitted from the light emitting element 4 is collected by the light projecting lens 12, narrowed to a predetermined shape by the aperture 10, reflected by the reflection mirror 15, and irradiated from the irradiation port 16 in a predetermined direction.

  That is, the focal position is determined by the distance between the light emitting point of the light emitting element 4 and the light projecting lens 12, and the aperture 10 narrows the light beam shape to a desired shape. The emission direction is determined by the angle of the reflection mirror 15. As a result, the light emitted from the light emitting element 4 has the spot size and shape required at a desired position.

  Next, the configuration on the light receiving side in the optical unit 1 will be described. The light receiving element 5 is an example of a light receiving means, and is, for example, a photodiode. The light receiving element 5 is mounted on the other surface of the die pad 3 facing the second cavity 8 using a silver paste or the like.

  The second cavity 8 is provided with a land portion (not shown) that is electrically connected to a predetermined lead 6. The light receiving element 5 is electrically connected to the land portion by a wire (not shown) and enters the light receiving element 5. An electrical signal such as a voltage corresponding to the amount of light is output from the predetermined lead 6.

  The second cavity 8 includes a window portion 17 as a second opening. The window portion 17 is provided side by side with the irradiation port 16 on the bottom wall portion, which is another wall portion of the package 2 constituting the second cavity 8, and is formed when the package 2 is molded.

  A condensing lens 18 as a condensing means is attached to the window portion 17. The condensing lens 18 is a convex lens and condenses light incident from the outside onto the light receiving element 5. A convex positioning portion 18 a is provided on one surface of the condenser lens 18. The window portion 17 has a shape that matches the outer shape of the positioning portion 18a, and is set so that the position of the condenser lens 18 is uniquely determined when the positioning portion 18a is fitted to the window portion 17 and fixed by bonding or the like. .

  Now, light enters the light receiving element 5 from a direction substantially orthogonal to the die pad 3. Thereby, in the optical unit 1, the direction of the light emitted from the light emitting element 4 and the direction of the light incident on the light receiving element 5 are substantially orthogonal to each other. Therefore, the reflection mirror 15 is provided to change the direction of the light emitted from the light emitting element 4 so that the reflected light of the light emitted from the light emitting element 4 can enter the light receiving element 5.

  Although not shown, a band pass filter (BPF) is provided as necessary as a selection means for selecting only the wavelength of light emitted from the light emitting element 4. For example, a band pass filter is provided in the window portion 17 so as to overlap the condenser lens 18. Alternatively, a band pass layer may be formed on the surface of the condenser lens 18.

  Further, it may be configured to be combined with a lens that can cut light having a wavelength shorter than that of adding a trace amount of arsenic or the like. Furthermore, when used in an environment that is not affected by external light, the band-pass filter may not be necessary.

  In the optical unit 1, the light emitting element 4 and the light receiving element 5 are mounted on the die pad 3, but the die pad 3 has a sufficient space. For this reason, as shown by a two-dot chain line in FIGS. 1 and 2, it is possible to mount a surface mount type electric component 19 on the die pad 3 and to integrate an electric circuit around the light emitting / receiving element.

  Further, in order to mount the optical unit 1, the fixing groove 20 may be provided in the package 2. The fixed groove 20 is formed, for example, by forming a V-shaped groove extending in the long side direction of the package 2 on the outer surface of both side walls of the package 2. Further, a reference portion 21 is formed in the package 2 on the first cavity 7 side, and is used as a reference point during assembly.

  Next, the operation of the optical unit 1 of the present embodiment will be described. FIG. 5 shows an operation example of the optical unit 1 of the present embodiment, FIG. 5 (a) is a side view, and FIG. 5 (b) is a front view. In FIG. 5A, the optical unit 1 is shown in cross section.

  The optical unit 1 is used as, for example, a reflection-type optical sensor that detects the presence or absence of the detection target 22 at a predetermined distance and the passage of the detection target 22. The light emitted from the light emitting element 4 is collected by the light projecting lens 12, becomes a beam light that is narrowed to a predetermined shape by the aperture 10, is reflected by the reflection mirror 15, and is irradiated from the irradiation port 16 to the outside.

  When the detected object 22 is positioned in front of the irradiation port 16, the light emitted from the light emitting element 4 is reflected by the detected object 2. Part of the light reflected by the detection object 22 returns to the direction of the optical unit 1 and enters the condenser lens 18 aligned with the irradiation port 16. In addition, by providing a band pass filter, it is possible to transmit only light having a wavelength emitted from the light emitting element 4 and prevent other external light from entering.

  The light incident on the condenser lens 18 is condensed and incident on the light receiving element 5. In this way, when the return light from the light emitting element 4 enters the light receiving element 5, a predetermined voltage is output from the lead 6 as an electrical signal. Thereby, it can be detected that the detected object 22 is present.

  Next, the structure which attaches the optical unit 1 of this Embodiment to an apparatus is demonstrated. FIG. 6 shows an example of the mounting configuration of the optical unit 1 of the present embodiment, FIG. 6 (a) is a front view of the mounting mechanism, and FIG. 6 (b) is a front view showing the mounting state.

  The attachment mechanism 23 includes a mount portion 24, a holding plate 25, and a fixing screw 26. The holding plate 25 has a claw portion 25 a that fits in the fixing groove 20 provided in the optical unit 1, and is fixed to the mount portion 24 with a fixing screw 26.

  When attaching the optical unit 1, the fixing screw 26 is loosened, the optical unit 1 is inserted between the opposing claw portions 25 a, and the claw portions 25 a are fitted into the fixing grooves 20. Then, the holding plate 25 is deformed by tightening the fixing screw 26, and the optical unit 1 is sandwiched from the left and right sides by the claw portions 25a. Thereby, as shown in FIG. 6B, the optical unit 1 is held by the mounting portion 24 by the holding plate 25 in a state where the claw portion 25 a is fitted in the fixing groove 25.

  As described above, in the optical unit 1 of the present embodiment, the light emitting element 4 is mounted on one surface of the die pad 3 and the light projecting lens 12 is reflected on the package 2 on which the light receiving device 5 is mounted on the other surface. The holding part of the mirror 15 and the condensing lens 18, and further the aperture 10 are integrally formed. Thereby, since each component can be mounted by passive alignment and desired position accuracy can be obtained, assembly cost can be reduced.

  And since the optical unit 1 is small, there are few restrictions on an installation place, and when using it as an optical sensor which detects a to-be-detected object, application to various apparatuses is attained.

  In the present embodiment, the reflection mirror 15 is provided to change the optical path of the light emitted from the light emitting element 4. However, when the package 2 is molded, the mirror 2 is held by a simple mold. This is because the portion 14 can be formed. Therefore, if the mirror holding part can be integrally provided on the window part 17 side, it is conceivable to change the optical path of the light incident on the light receiving element 5.

  Since the optical unit of the present invention is small, it can be applied to an optical sensor that detects the presence of an article, an optical reader that reads a barcode, and the like. In addition, since the occurrence of crosstalk is suppressed, application to an optical communication device is also conceivable.

It is a sectional side view which shows the structural example of the optical unit of this Embodiment. It is a top view which shows the structural example of the optical unit of this Embodiment. It is a bottom view which shows the structural example of the optical unit of this Embodiment. It is a front view which shows the structural example of the optical unit of this Embodiment. FIG. 5A is a side view, and FIG. 5B is a front view, illustrating an operation example of the optical unit of the present embodiment. FIG. 6A is a front view of an attachment mechanism, and FIG. 6B is a front view showing an attachment state of the optical unit according to the present embodiment. FIG. 7A is an external perspective view, and FIG. 7B is an exploded perspective view illustrating a configuration example of a conventional light emitting element. It is sectional drawing which shows the attachment structural example of each conventional optical component.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical unit, 2 ... Package, 3 ... Die pad, 4 ... Light emitting element, 5 ... Light receiving element, 6 ... Lead, 7 ... 1st cavity, 8 * 2nd cavity, 9 ... wire, 10 ... aperture, 11 ... lens holding part, 12 ... projection lens, 13 ... cover, 14 ... mirror holding part, 15・ ・ ・ Reflection mirror, 16 ... Irradiation port, 17 ... Window part, 18 ... Condensing lens, 18a ... Positioning part, 19 ... Electrical component, 20 ... Fixed groove, 21 ... Reference section

Claims (9)

A package containing light emitting means and light receiving means;
The inside of the package is partitioned to form a first cavity and a second cavity, and the light emitting means is mounted on the surface on the first cavity side, and the light receiving means is mounted on the surface on the second cavity side. A die pad to be mounted;
A first opening provided on one wall portion of the package constituting the first cavity, through which light emitted from the light emitting means passes;
A second opening provided on another wall of the package constituting the second cavity, through which light incident on the light receiving means passes;
A light projecting means for condensing the light emitted from the light emitting means;
A light projecting means holding portion formed integrally with the package between the light emitting means and the first opening, to which the light projecting means is attached;
An optical path changing means for changing a traveling direction of the light collected by the light projecting means;
An optical path changing means holding part formed integrally with the package and to which the optical path changing means is attached;
An optical unit comprising: a condensing unit that is attached to the second opening and condenses light from the outside.   2. The optical unit according to claim 1, wherein the first opening has a shape for narrowing light emitted from the light emitting means.   2. The optical unit according to claim 1, wherein the light projecting means is a spherical ball lens.   2. The optical unit according to claim 1, wherein the condensing means is a lens, and the second opening has a shape for holding the lens.   2. The optical unit according to claim 1, further comprising selection means for causing the light receiving means to enter through the light having a wavelength emitted from the light emitting means.   2. The optical unit according to claim 1, wherein the optical path changing means is a reflecting mirror, and the optical path changing means holding part has a shape for fixing the reflecting mirror at a constant angle.   The optical unit according to claim 1, wherein an electrical component is mounted on at least one surface of the die pad.   The optical unit according to claim 1, wherein a fixing groove is provided on an outer surface of the side wall portion of the package. 2. The optical unit according to claim 1, wherein the light emitting means is integrally provided with a light receiving means for detecting a light emission output.

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