JPH06204508A - Optical detector - Google Patents

Abstract

PURPOSE:To increase the hermetic sealability of a light-emitting device or a photodetector and to facilitate its preparation with high precision by forming a waveform composition element directly or stacking it on the surface of a translucent resin which makes a hermetic seal of the photodetector. CONSTITUTION:An electrode pad of photodetectors 2B and 2C is connected to a lead frame by wire bonding. And the photo-detectors 2B and 2C are hermetically sealed by using a transparent resin 6 according to the transfer mold method. After a package with diffraction gratings 9A, 9B, and 9C formed on the surface of the transparent resin 6 is arranged on a semiconductor laser holder 5 containing a semiconductor laser 1, the light-emitting point of the semiconductor laser is so positioned as to be in the preset position. Then, the package is bonded to the laser holder 5 and fixed. This makes a hermetic seal, assuring relliability and low-cost production, forming in precision, and making the positional relationship difficult to change after the formation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical detecting device for detecting a predetermined parameter of a target object by receiving a light beam from the target object.

[0002]

2. Description of the Related Art Conventionally, as a device for receiving light from an object to obtain information, a device for highly accurately determining a physical quantity such as movement or displacement of the object, for example, an optical encoder,
There are laser Doppler velocimeter, laser interferometer, etc. Further, although it is a field different from the measuring device, there is also an optical pickup which records digital information as represented by a compact disc with minute unevenness, irradiates this with light, and reads the information.

In these devices, light is emitted from a light emitting element by an electric signal, and light returning from an object through an optical component is received again by a light receiving element and converted into an electric signal to obtain respective information. .

[0004]

In such a device, it is required to shield the light emitting element and the light receiving element from the outside world, and in particular, it is necessary to enhance the airtightness.

At the same time, the light emitting element or the light receiving element and the element for separating and combining the light fluxes are manufactured by accurately positioning them in a predetermined positional relationship in order to enhance the measurement accuracy, and the positional relationship is always maintained. There are also challenges that must be maintained.

In view of the above-mentioned new necessity of the conventional example, the present invention enhances the airtightness of the light emitting element or the light receiving element, and performs highly accurate alignment with the element for separating, combining, etc. It is an object of the present invention to provide an optical detection device that can be easily manufactured and that can maintain its positional relationship with high accuracy.

[0007]

[Means for Solving the Problems] To achieve the above object,
The present invention relates to a detection device for detecting a target object by combining two light fluxes from the target object with a light-receiving element and receiving the light with a light-receiving element. A transparent resin surface for hermetically sealing the light-receiving element. In addition, the multiplexing element is formed directly or by stacking.

According to another aspect of the present invention, a light beam from a light emitting element is separated or deflected by an optical element, the separated or deflected light beam is applied to a target object, and the light beam from the target object is detected by a light receiving element. In an apparatus that detects a target object by receiving light, the optical element is formed directly or laminated on a light-transmitting resin surface that hermetically seals the light emitting element.

According to another invention of the present application, a light flux from a light emitting element is separated or deflected by an optical element, and two light fluxes passing through the optical element and an object are multiplexed by a multiplexing element and received. In a detection device that detects the target object by receiving light by an element, at least one of the optical element and the multiplexing element is directly or laminated on a light-transmitting resin surface that hermetically seals the light emitting element and the light receiving element. Are formed.

Further, according to another invention of the present application, a light beam from a light emitting element is separated by an optical element to form at least two light beams, which are made incident on a diffraction grating to be measured, and at least two diffracted light generated are combined. In the detection device for detecting the relative displacement information of the diffraction grating to be measured by receiving the light by the light receiving element by causing the light interference with the optical element, the surface of the transparent resin that hermetically seals the light receiving element is combined with the optical element. At least one of the wave elements is formed directly or laminated.

[0011]

EXAMPLE FIG. 1 is a schematic sectional view showing a first example. In the figure, 1 is a semiconductor laser, 2 is a light receiving element, 4 is a lead frame bed on which the light receiving elements 2B, 2B ', 2C and 2C' are mounted, and 41 is provided on the lead frame bed. A hole for transmitting the light emitted from the semiconductor laser 1, 5 is a holder of the semiconductor laser unit, 6 is a transparent resin 9B for hermetically sealing the light receiving element,
9C is a diffraction grating and 10 is a scale. Light receiving element 2
B ′ and 2C ′ are on the back sides of the light receiving elements 2B and 2C in the direction perpendicular to the paper surface, and do not appear in the drawing.

In the present embodiment, first, a lead is provided with a hole 41 so that light emitted from the semiconductor laser 1 as a light receiving element can be transmitted through a portion of the lead frame for mounting the light receiving element on the IC bed portion 4. The light receiving elements 2B, 2B ', 2C, 2C' are die-bonded to the frame, and the electrode pads of the light receiving elements 2B, 2B ', 2C, 2C' and the lead frame are wire-bonded. And
The light receiving elements 2B, 2B ', 2C, 2C' are hermetically sealed by using the transparent resin 6 by the transfer molding method.
The steps up to this point are the same as those in the conventional method of manufacturing a plastic package for a semiconductor device.

Next, a resist is coated on the glass substrate,
The pattern of the diffraction grating is exposed and the resist is developed to form a resist pattern of the diffraction grating on the glass substrate. Then, this glass substrate is dry-etched to form a diffraction grating on the glass substrate, and then the resist is peeled off. In this way, the diffraction grating mold is manufactured.

Next, an ultraviolet curable resin is applied onto the glass substrate mold, the light receiving portions of the respective light receiving elements are aligned with the diffraction grating formed on the glass substrate, and the surface of the transparent resin 6 of the package is fixed. Ultraviolet rays are radiated from the back side of the glass substrate (mold) in contact with the mold to cure the ultraviolet curable resin.
After that, when the package is released from the glass substrate (mold), the ultraviolet curable resin is transferred to the surface of the transparent resin 6 which is the package as diffraction gratings 9A, 9B, 9B ', 9C and 9C'. FIG. 2 is a top view showing a state in which each diffraction grating is formed on the package surface.

The package in which the diffraction gratings 9A, 9B, 9B ', 9C and 9C' are formed on the surface of the transparent resin 6 in this manner is placed on the semiconductor laser holder 5 having the semiconductor laser 1 built therein, and the semiconductor laser is provided. After aligning so that the light emitting point of is at a predetermined position, the package and the semiconductor laser holder 5 are bonded and fixed.

After that, the electric terminals are connected to the lead wires to form a head of the optical displacement sensor.

In the optical displacement sensor head manufactured by the above manufacturing method, the light receiving element 2 which is a semiconductor element is used.
B, 2B ', 2C and 2C' are hermetically sealed by the transparent resin 6 to ensure reliability and are manufactured at low cost. Also, the diffraction gratings 9A, 9B, 9B ', 9C, 9C'
The method for providing the package on the surface of the package is very simple and is performed with the positioning with respect to the light receiving portion, so that the package can be formed with high accuracy. In addition, the positional relationship does not easily change even after the formation.

Next, the operation of the optical displacement sensor configured as described above will be described. In this embodiment, the luminous flux emitted from the semiconductor laser 1 is received by the light receiving elements 2B, 2B ′, 2
The light enters from the back surface of the package containing C and 2C ′, passes through the hole 41 provided in the bed portion 4 of the lead frame, is transmitted and diffracted by the diffraction grating 9A formed on the package surface, and the 0th-order diffracted light R0 , + 1st order diffracted light R + 1, −
The first-order diffracted light R-1 is divided into three and emitted from the package.

The light beam R0 traveling straight through the diffraction grating 9A is reflected and diffracted at a point P1 on the diffraction grating 10A formed on the scale 10 and divided into + 1st-order diffracted light R0 + 1 and -1st-order diffracted light R0-1. Phase modulated.

The phase of the + 1st order diffracted light is + 2πX / P, -1
The phase of the next-order diffracted light R0-1 is shifted by -2πX / P. However, X is the amount of movement of the diffraction grating 10A of the scale 10, and P is the pitch of the diffraction grating 10A.

In the above description, the same phenomena as those of the diffraction gratings 9B and 9C occur in the diffraction gratings 9B 'and 9C', so that the details will be omitted. The + 1st-order diffracted light R0 + 1 is transmitted and diffracted by the diffraction grating 9B formed on the surface of the package, and the 0th-order diffracted light R0 + 10 and the -1st-order diffracted light R0 + 1-1.
And other light fluxes. Among these, the −1st order diffracted light R0 + 1-1 is extracted perpendicularly to the diffraction grating surface, and the phase of the wavefront is + 2πX / P.

The -1st-order diffracted light R0-1 is transmitted and diffracted by the diffraction grating 9C formed on the surface of the package, and is split into the 0th-order diffracted light R0-10, the + 1st-order diffracted light R0-1 + 1 and other light beams. Of these, the −1st order diffracted light R0-1
+1 is taken out perpendicular to the diffraction grating surface and the phase of the wavefront is
-2πX / P.

Here, if the diffraction grating 9B is shifted with respect to 9C in the arrangement phase relationship of the grating by P / 4, the phase of the wavefront of the + 1st-order diffracted light R0-1 + 1 is further -2π (P / 4).
A deviation of / P = -π / 2 results in -2πX / P-π / 2.

The light beam R + 1 which is + 1st order diffracted by the diffraction grating 9A formed on the surface of the transparent resin 6 is reflected and diffracted at the point P2 on the diffraction grating 10A on the scale 10, and the -1st order diffracted light R + 1-1. , 0th-order diffracted light R + 10 and other luminous fluxes, which are respectively phase-modulated. Of these,-
The phase of the first-order diffracted light R + 1-1 is shifted by −2πX / P, is incident on the diffraction grating 9B, and goes straight as it is at 0.
The phase of the wavefront of the next-order diffracted light R + 1-10 is −2πX / P.

The light beam R-1 which is -1st order diffracted by the diffraction grating 9A formed on the surface of the transparent resin 6 is reflected and diffracted at the point P3 on the diffraction grating 10A on the scale 10, and the + 1st order diffracted light R -1 + 1, 0th-order diffracted light R-10, and other light fluxes are split and subjected to phase modulation. Of these, +
The phase of the first-order diffracted light R-1 + 1 is shifted by + 2πX / P, is incident on the diffraction grating 9B, and goes straight as it is at 0.
The phase of the wavefront of the next-order diffracted light R-1 + 10 is + 2πX / P.

The light beams R + 1-10 and R0 + 1-1 whose optical paths are superposed by the diffraction grating 9B become interference light and enter the light receiving element 2B. The interference phase at this time is {+ 2πX / P}-{-2πX / P} = 4πX / P, and one cycle of bright and dark signals is generated every time the diffraction grating 10A on the scale 10 moves by ½ pitch.

The light beams R-1 + 10 and R0-1 + 1 whose optical paths are superposed by the diffraction grating 9C become interference light and enter the light receiving element 2C. The interference phase at this time is {−2πX / P−π / 2} − {+ 2πX / P} = 4πX / P−π / 2, which is 1 every time the diffraction grating 10A on the scale 10 moves by ½ pitch. The light and dark signal of the cycle is generated, and the light receiving element 2
The timing of light and dark is different from B by 1/4 cycle.

Further, in the diffraction gratings 9A 'and 9B', the arrangement phase relationship of the gratings is shifted by P / 2 with respect to the diffraction gratings 9A and 9B, respectively, so that the phase of the wavefront is shifted by π. Therefore, the light / dark signals whose light / dark timings are shifted by 1/2 cycle with respect to the respective light / dark signals are received by the light receiving elements 2B 'and 2C', respectively. The signals from the respective light receiving elements are the light receiving elements 2B, 2B '.
Is converted into a two-phase signal by using the difference signal of the output of the scale and the difference signal of the outputs of the light receiving elements 2C and 2C ', and by utilizing this, the displacement amount and the displacement direction of the scale 10 are obtained by a known method.

FIG. 3 is a schematic sectional view showing the second embodiment. In the figure, the same members as those described above are given the same reference numerals.

In this embodiment, the light receiving element 2 is made of the transparent resin 6
A part of the mold of the transfer mold at the time of sealing is made into a convex shape, and a concave part 61 is formed in a part of the package. The concave portion has a size such that the convex lens 8 and the package do not interfere with each other, as will be described later. Other configurations are similar to those of the first embodiment, and a package in which the light receiving element 2 is incorporated is obtained.

Next, in this embodiment, a resist is applied on the glass substrate 91, the diffraction grating pattern is exposed, and the resist is developed. Then, this glass substrate 91 is dry-etched, the diffraction grating 9 is engraved on the glass substrate 91, and the resist is peeled off. Next, the diffraction grating 9 for emitted light
The convex lens 8 is formed on the rear surface side where A is formed by transferring it to the glass substrate 91 using a mold and an ultraviolet curable resin as in the case of forming the diffraction grating in the first embodiment.

Next, the glass substrate 91 and the above-mentioned transparent resin package are combined with the diffraction gratings 9B, 9B ', 9C, and
9C 'and the light receiving portion of each light receiving element are positioned and adhered to each other to form a diffraction grating on the transparent resin. At this time, the concave portion 61 is provided in the package so that the convex lens 8 formed on the glass substrate 91 does not interfere with the package.

In this way, the package in which each diffraction grating and the convex lens 8 are formed on the surface of the transparent resin 6 is placed on the semiconductor laser holder 5 having the semiconductor laser 1 built therein,
After the light emitting point of the semiconductor laser is aligned with the convex lens 8 at a predetermined position, the package and the semiconductor laser holder 5 are bonded and fixed.

After that, the respective electric terminals are connected to the lead wires to form the head of the optical displacement sensor. The operation is similar to that described above.

In this embodiment, the divergent light beam emitted from the semiconductor laser 1 is made into a parallel light beam or a convergent light beam, so that the signal light intensity is increased or the signal changes in response to disturbances related to the arrangement during mounting and use. It becomes a small optical displacement sensor.

FIG. 4 is a schematic sectional view showing the third embodiment. The same members as those described above are given the same reference numerals.
FIG. 5 is a top view of the lead frame portion.

In this embodiment, the LED 11 as a light emitting element and each light receiving element are built in one transparent resin package. Therefore, the light emitting element L
The divergent light of the ED 11 enters the light receiving portion of each light receiving element, and S
There is a problem that the / N ratio decreases. Therefore, LED
The bed portion of the lead frame 4 on which 11 is mounted is pressed to be higher than the bed portion on which each light receiving element is mounted. With such a shape of the lead frame, the height difference between the light emitting portion of the LED 11 and the light receiving portion of the light receiving element can be made large, and the incident of extra light from the LED 11 to the light emitting portion can be reduced. Is possible.

Diffraction gratings are formed on the transparent resin package thus formed by the same method as in the first embodiment. The operation is similar to that described above.

Since the optical displacement sensor formed as described above has a light emitting element built therein, it is extremely small in size, suppresses stray light inside the package, secures an S / N ratio, and is extremely low in cost. .

FIG. 6 is a schematic sectional view showing the fourth embodiment, and FIG. 7 is a top view of the lead frame portion. The same members as those described above are given the same reference numerals.

In this embodiment, as described in the third embodiment, when the light emitting element and the light receiving element are incorporated in one transparent resin package, the mounting heights of the light emitting section and the light receiving section are secured, and S The purpose is to improve the / N ratio.

For this reason, in this embodiment, the base 2 of the four light receiving elements is made larger in size and is manufactured in common, and mounted on the lead frame. Next, the LED 11 is mounted on the surface of the light receiving element other than the light receiving portion and the extraction electrode portion. After that, each electrode portion and the electrode terminal portion of the lead frame are connected by a wire bonder. Then, the package is hermetically sealed with the transparent resin 6.

The method of forming the diffraction grating 9 on the transparent resin surface is the same as in the first embodiment. The operation is similar to the above.

FIG. 8 is a schematic sectional view showing the fifth embodiment, and FIG. 9 is a top view of the same. The same members as those described above are given the same reference numerals. In this embodiment, as described above,
In the formed optical displacement sensor, as a method for preventing scattered light inside the package from the LED 11 which is a light emitting element from entering the light receiving portion, as shown in FIG. 8, the transparent resin 6 between the light emitting point and the light receiving portion is used. A groove 62 is formed in the groove to cut the internal scattered light before reaching the light receiving portion. The method of forming the groove 62 is the same as that used in the second embodiment, in which the mold used for forming the package has the same shape. Others are the same as those described above.

FIG. 10 is a schematic sectional view showing a sixth embodiment, and FIG. 11 is a top view of the lead frame portion. The same members as those described above are given the same reference numerals.

In this embodiment, a light-absorbing paint 112 is applied to the surface of the light receiving element 2 between the LED 11 and the light receiving portion to suppress the multiple reflection by the light-shielding aluminum on the package surface and the surface of the light receiving element 2 to scatter light to the light receiving portion. Prevent incident. Others are the same as the above.

As the light emitting element in each of the above embodiments, a semiconductor laser, a light emitting diode or the like can be used.

As the light receiving element, a photodiode, an avalanche photodiode, a pin photodiode, a CCD, or a light receiving IC having a circuit for amplifying or processing the photocurrent output from these light receiving portions can be used. .

As a method of manufacturing a grating as an optical component, a mold is formed, an ultraviolet curable resin is poured into the mold, a transfer member is placed on the mold, and the resin is irradiated with ultraviolet rays to cure the resin and transferred to the transfer member. There is a replica method in which the resist is applied, an etching method in which a resist is applied to a glass substrate, a pattern is exposed by a mask or a reticle, and the resist is developed, followed by etching. Also,
The resist may be directly drawn by EB (electron beam), developed, and etched. Furthermore, when the above resist is exposed, it may be hard-baked to form a grating. Alternatively, the grating may be directly formed on the surface of the transparent resin 6.

By combining the embodiments, it is possible to further improve the S / N ratio.

[0051]

As described above, according to the present invention, it becomes possible to improve the airtightness of the light emitting element or the light receiving element, facilitate the high precision manufacturing, and realize the optical detecting device capable of maintaining the high precision.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a first embodiment.

FIG. 2 is a schematic top view showing the first embodiment.

FIG. 3 is a schematic sectional view showing a second embodiment.

FIG. 4 is a schematic sectional view showing a third embodiment.

FIG. 5 is a schematic top view of a lead frame portion showing a third embodiment.

FIG. 6 is a schematic sectional view showing a fourth embodiment.

FIG. 7 is a schematic top view of a lead frame portion showing a fourth embodiment.

FIG. 8 is a schematic sectional view showing a fifth embodiment.

FIG. 9 is a schematic top view showing a fifth embodiment.

FIG. 10 is a schematic sectional view showing a sixth embodiment.

FIG. 11 is a schematic top view of a lead frame portion showing a sixth embodiment.

[Explanation of symbols]

 1 semiconductor laser 2B, 2C light receiving element 3 glass epoxy substrate 4 lead frame 41 through hole 5 semiconductor laser holder 6 transparent resin (package) 61 recess 62 groove 8 plano-convex lens 9A, 9B, 9B ', 9C, 9C' diffraction grating 91 glass substrate 10 scale 10A scale diffraction grating 11 LED 12 main scale grating 14 index grating 16 index grating 40 main scale 42 light source 44 index scale 46 substrate 48 light receiving element 50 lens

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasushi Kaneda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (5)

[Claims] 1. A detection device for detecting the target object by combining two light fluxes from the target object by a multiplexing element and receiving the light by a light receiving element, and a transparent resin for hermetically sealing the light receiving element. An optical detection device characterized in that the multiplexing element is directly or laminated on the surface. 2. The target object by separating or deflecting a light beam from a light emitting element by an optical element, irradiating the separated or deflected light beam to a target object, and receiving a light beam from the target object by a light receiving element. In the apparatus for performing the detection, the optical detection device is characterized in that the optical element is formed directly or laminated on the surface of a light-transmissive resin that hermetically seals the light emitting element. 3. A light beam from a light emitting element is separated or deflected by an optical element, and two light beams passing through the optical element and passing through a target object are combined by a combining element and received by a light receiving element. In a detection device for detecting a target object, at least one of the optical element and the multiplexing element is formed directly or laminated on a transparent resin surface that hermetically seals the light emitting element and the light receiving element. Optical detection device. 4. A light beam from a light emitting element is separated by an optical element to form at least two light beams, which are made incident on a diffraction grating to be measured, and at least two diffracted lights generated are combined and interfered by a combining element to receive light. In the detection device for detecting relative displacement information of the diffraction grating to be measured by receiving light by the element, at least one of the optical element and the multiplexing element is directly attached to the light-transmitting resin surface that hermetically seals the light receiving element. Alternatively, the optical detection device is formed by stacking. 5. The optical detection device according to claim 1, wherein the optical element or the multiplexing element is a diffraction grating.