JPH09189515A - Optical displacement detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical displacement detection device which can mechanically and easily locate a light reception element and can be assembled by utilizing the side surface of the light reception element as an assembly reference surface even if the light reception element is formed of a wafer by half cutting. SOLUTION: A bottom surface which is a bottom surface B opposite to a light reception surface A of a light reception element IC 21' with the light reception surface A where a photo sensitive zone is formed with a fine pitch is fixed to a first assemble reference surface 32 of a substrate 31 and at the same time a positioning protrusion 35 with a pair of second assembly reference surfaces 33 and 34 which are at right angle to the surface 32 and are mutually in parallel is fixed. A cylindrical pin 61 is arranged in parallel with the assembly reference surface 33 between one assembly reference surface 33 of the positioning protrusion 35 and a side surface C of the light reception element IC 21'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical displacement detecting device. Specifically, a main scale having an optical grating in which light transmitting portions and light blocking portions are alternately arranged at a constant pitch, an illuminating unit arranged on one side of the main scale, and the illumination with the main scale interposed therebetween. The present invention relates to an optical displacement detection device including a light receiving unit arranged on the opposite side of the system and detecting the relative displacement amount between the main scale and the light receiving unit.

[0002]

BACKGROUND ART A main scale having an optical grating having a constant pitch and an index scale having an optical grating corresponding to the main grating are arranged so as to be capable of relative displacement, and one side is sandwiched between these scales. An optical displacement that arranges the light emitting device and the light receiving device on the other side, obtains a detection signal by the light receiving device when both scales are relatively displaced, and then detects the relative displacement amount of both scales based on this detection signal. Detection devices are known.

Recently, in this type of optical displacement detection device, further miniaturization and cost reduction are required, so that the photodetector itself is composed of a photodetector array of a constant pitch and also serves as an index scale. An optical displacement detection device having such a structure has been proposed. As shown in FIG. 1, this is because the light transmitting portion 12A having substantially the same width is formed on the glass substrate 11.
A main scale 13 having an optical grating 12 in which the light shields 12B and the light blocking portions 12B are alternately arranged at a constant pitch; a lighting unit 16 including a light source 14 and a collimator lens 15 arranged on one side of the main scale 13; The light-receiving element 21 is arranged opposite to the illuminating means 16 with the main scale 13 interposed therebetween.

Here, as the light receiving element 21, as shown in FIGS. 2 and 3, a P-type semiconductor layer 24A is diffused and formed at a constant pitch on an N-type semiconductor substrate 23 made of silicon to form a photosensitive band 25. Thing, that is, N-type semiconductor substrate 2
3 and the P-type semiconductor layer 24A, the light-receiving element IC 21A having a structure in which the photosensitive band 25 is formed, or as shown in FIGS. 4 and 5, a P-type semiconductor layer 24B is formed on the N-type semiconductor substrate 23. There is known a light receiving element IC21B having a structure in which a transparent insulating film 26 made of silicon oxide or the like is formed thereon, and then a grid-like light shielding film 27 is formed on the insulating film 26 by a metal (aluminum) thin film.

Since these light receiving elements IC21A and 21B (hereinafter referred to as "light receiving element IC21 '") function as a conventional index scale and a light receiver, they have the advantages of a simple structure and high reliability. Moreover, since it can be manufactured by the IC process, it has an advantage that an amplifier circuit and the like can be built in. In such an optical displacement detection device, the photosensitive band 2 of the light receiving element IC 21 'is
When the interval of 5 is a fine pitch of several tens of μm or less, the positioning of the light receiving element IC 21 ′ with respect to the main scale 13 is
Strict positioning on the order of several tens of μm is required.

As shown in FIG. 6, the rotational direction of the posture variation in positioning is the ROLL direction which rotates about the x-axis parallel to the relative displacement direction of the main scale 13 and the light receiving element IC21 ', and the x-axis. The PITCH direction that rotates about the y-axis that is orthogonal to the light-receiving surface of the light-receiving element IC21 'and the YAW direction that rotates about the z-axis that is orthogonal to the x-axis and the y-axis. Be divided.

When mechanically positioning the main scale 13 in each of these rotation directions, the light receiving element I
C21 'bottom B (side opposite to light-receiving surface A) and side C
It is conceivable to use (the side surface along the arrangement direction of the photosensitive band 25) as an assembly reference surface. That is, the light receiving element IC
The bottom surface B of 21 'has good parallelism with the light receiving surface A, and the side surface C of the light receiving element IC 21' has a photosensitive band 2 at the time of cutting.
Since it is cut along the arrangement direction of No. 5, it has parallelism with these, so it is conceivable to use these as the assembly reference plane.

However, in actuality, in positioning the light receiving surface A of the light receiving element IC 21 ′ and the main scale 13, it is extremely difficult to use each surface of the light receiving element IC 21 ′ as a mechanical assembly reference plane. Because the light receiving element I
This is because the chip of C21 'is very small, such as a few millimeters square, and wire bonding is performed to extract a signal from the light receiving element IC21'. So, conventionally,
After actually assembling the main scale 13 and the light receiving element IC21 ', the position of the light receiving element IC21' was adjusted while observing the detection signal obtained from the light receiving element IC21 'when the both were relatively displaced.

[0009]

However, the conventional adjustment method described above has a problem that the adjustment takes time and effort. Therefore, if the substrate on which the light receiving element IC21 'is mounted is used as an indirect reference plane, mechanical positioning is possible. For example, as shown in FIGS. 7 and 8, the surface of the substrate 31 facing the main scale 13 is a flat first assembly reference surface 32, and the first assembly reference surface 32 is formed with respect to the first assembly reference surface 32. Is provided with a pair of second assembly reference surfaces 33, 34 that are perpendicular to each other and parallel to each other, and the side surface C of the light receiving element IC21 'is brought into contact with the second assembly reference surface 33 of one of the positioning projections 35. The bottom surface B is bonded to the first assembly reference surface 32 of the substrate 31.

Then, since the bottom surface B of the light receiving element IC21 'is adhered to the first assembly reference surface 32 of the substrate 31, positioning is performed in parallel with the main scale 13 with the first assembly reference surface 32 as a reference. For example, PITCH direction and R
The rotation in the OLL direction can be restricted. Further, since the side surface C of the light receiving element IC21 'is in contact with one of the second assembly reference surfaces 33 of the positioning projections 35, the main scale 13 is based on the other second assembly reference surface 34 parallel thereto.
If it is positioned at a right angle to, the rotation in the YAW direction can be restricted.

By the way, normally, the light receiving elements IC21 'are individually separated from the wafer by a method called half-cut. This method begins with the wafer 4 as shown in FIG.
In order to individually separate the light-receiving elements IC21 'on the first light-receiving element IC2' by a dicer (half-cutting machine)
Insert a not-complete cut groove 42 at the boundary of 1 '(half cut). At this time, the adhesive tape 43 is attached to the bottom surface. Subsequently, as shown in FIG. 10, the half-cut wafer 41 is placed on the curved base 44, and pressure is applied from above. Then, the light receiving elements IC21 'are separated along the cut grooves 42.

This method is lower in cost and advantageous in handling as compared with the full-cut method for completely separating the light receiving element IC21 '. That is, since the unit price of the light receiving element IC21 'includes a step for cutting, the cutting time can be shortened in the half cut rather than the full cut, and the cost can be reduced. Further, when cutting the light receiving element IC21 ', a round blade edge called a blade is cutting while rotating at a high speed, and a high pressure coolant (pure water etc.) is sprayed toward the blade edge to cool it. However, in the case of half-cutting, since the entire wafer 41 is fixed by the adhesive tape 43, stable cutting is possible, and the light-receiving element IC 21 ′ does not peel off from the tape 43 during cutting. Therefore, it is easy to handle since it is a single wafer.

On the other hand, however, when the light receiving elements IC21 'are individually separated, cracks can be generated in random directions from the uncut portions, so that the cross section of the light receiving element IC21' alone is as shown in FIG. It becomes a shape with a burr 45. In such a case, the side surface C of the light receiving element IC21 'cannot be used as an assembly reference.

An object of the present invention is to solve all of the problems of the prior art, to mechanically and easily position the light receiving element, and even when the light receiving element is formed from a wafer by half-cutting. An object of the present invention is to provide an optical displacement detection device that can be assembled by using the side surface of a light receiving element as an assembly reference surface.

[0015]

An optical displacement detection device according to the present invention comprises a main scale having an optical grating in which light transmitting portions and light blocking portions are alternately arranged at a constant pitch, and one side of the main scale. In the optical displacement detection device including an illuminating unit disposed on the main scale and a light receiving unit disposed on the opposite side of the main scale from the illuminating unit, the light receiving unit is opposed to the main scale. A substrate that is displaceably arranged and has a surface facing the main scale as a first assembly reference surface, and a board fixed to the first assembly reference surface of the board and perpendicular to the first assembly reference surface and parallel to each other. And a light receiving element having a pair of second assembly reference surfaces and a light receiving surface having a photosensitive band formed at a fine pitch, and a side surface opposite to the light receiving surface fixed to the first assembly reference surface of the substrate. When A cylindrical pin is provided between the side surface of the light receiving element and the second assembly reference plane of one of the positioning projections so as to be in contact therewith and arranged in parallel to the second assembly reference plane. And

According to this structure, the positioning with the main scale can be performed with the first assembly reference plane of the substrate and the second assembly reference plane of the positioning ridge much larger than the light receiving surface of the light receiving element as a reference. Therefore, the positioning can be performed mechanically and easily. That is, since the side surface opposite to the light receiving surface of the light receiving element is fixed to the first assembly reference surface of the substrate, if positioning is performed in parallel with the main scale with reference to the first assembly reference surface, the PITCH direction and The rotation in the ROLL direction can be restricted. Further, since the side surface of the light receiving element is in contact with one of the second assembly reference planes of the positioning projection through the pin, it is perpendicular to the main scale with the other second assembly reference plane parallel thereto. If the positioning is performed at, the rotation in the YAW direction can be restricted.

Further, since the pins have a cylindrical shape, the side surface of the light receiving element can be used as an assembly reference plane even when the light receiving element is formed by half-cutting from the wafer. That is, when the light receiving element is formed by half-cutting from the wafer, a burr is generated on the side surface of the light receiving element, but since the burr can be escaped by the columnar pin, the side surface of the light receiving element is used as an assembly reference plane. Therefore, it can be easily assembled. Moreover, if the pin has a cylindrical shape whose radius is smaller than the thickness of the light receiving element, when the light receiving element is pressed in the direction of the second assembly reference plane, the side surface of the light receiving element is stopped at a position in contact with the pin. Therefore, the positioning can be facilitated.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIG.
2 and FIG. 13, a detailed description will be given. In addition,
In the following description, the same components as those in the above-mentioned drawings are designated by the same reference numerals, and the description thereof will be omitted. FIG.
2 is a plan view of the light receiving means according to the present embodiment, and FIG. 13 is a sectional view thereof. The light receiving means is the main scale 1
The substrate 3 having a surface facing the third assembly as a first assembly reference surface 32.
1, a frame body 51 provided on the first assembly reference surface 32 of the substrate 31 and configured in a rectangular frame shape including the positioning protrusions 35, and a bottom surface B on the first assembly reference surface 32 of the substrate 31. The light receiving element IC 21 ′ to be fixed and the columnar pin 6
1 is provided.

The frame body 51 includes the positioning protrusion 35.
And the frame member 5 provided in parallel with the positioning protrusion 35.
2 and a pair of frame members 53 and 54 connecting both ends of the frame member 52 and the positioning ridge 35 to form a rectangular frame shape. The light receiving element IC 21 ′ and the pin 61 are housed in the frame 51, and then the resin 5 having a light transmitting property is provided.
5 is filled.

The pin 61 has a radius dimension r smaller than the thickness dimension t of the light receiving element IC21 ', and has a columnar shape which is 1/2 or more of the thickness dimension t of the light receiving element IC21'. Side face C and the positioning protrusion 3
5 is arranged in contact with one of the second assembly reference surfaces 33 and parallel to the second assembly reference surfaces 33 and 34.

Therefore, according to the configuration of the present embodiment, the first assembly reference plane 32 of the board 31 has the first assembly reference plane 32.
A bottom surface of a light receiving element IC21 'having a light receiving surface A having a pair of second assembly reference surfaces 33 and 34 that are perpendicular to and fixed to the B (the side surface opposite to the light receiving surface A) is fixed, and the cylindrical pin 61 is in contact with the side surface C of the light receiving element IC 21 ′ and one of the second assembly reference surfaces 33 of the positioning projections 35. The substrate 31 which is much larger than the light receiving surface A of the light receiving element IC21 '
With reference to the first assembling reference surface 32 and the second assembling reference surfaces 33 and 34 of the positioning protrusions 35, the main scale 13
Since it is possible to perform positioning with respect to, mechanical positioning is possible.

In this case, the bottom surface B of the light receiving element IC21 '
Since the (side surface opposite to the light receiving surface A) is fixed to the first assembly reference surface 32 of the substrate 31, if the positioning is performed in parallel with the main scale 13 with the first assembly reference surface 32 as a reference, the PITCH The rotation in the direction and the ROLL direction can be restricted. In addition, the side surface C of the light receiving element IC21 '
Is in contact with one of the second assembly reference planes 33 of the positioning projections 35 via the cylindrical pin 61, so that the main scale 1 is designed with the other second assembly reference plane 34 parallel thereto as a reference.
If the positioning is performed at a right angle to 3, the rotation in the YAW direction can be restricted.

Since the pin 61 has a cylindrical shape,
Even when the light receiving element IC21 'is formed by half-cutting from the wafer 41, the side surface C of the light receiving element IC21' can be used as the assembly reference plane. That is, when the light receiving element IC 21 ′ is formed by half-cutting from the wafer 41, the burr 45 is formed on the side surface C of the light receiving element IC 21 ′.
However, since the side surface C of the light receiving element IC21 'can be positioned while allowing the burr 45 to escape by the columnar pin 61, the side surface C of the light receiving element IC21' can be used as an assembly reference surface. Therefore, the light receiving element IC2
Even if 1'is created from the wafer 41 by half-cutting, it can be easily assembled.

Moreover, since the pin 61 has a columnar shape in which the radius dimension r is smaller than the thickness dimension t of the light receiving element IC21 'and is 1/2 or more of the thickness dimension t of the light receiving element IC21', the light receiving element IC21 is formed. By pressing 'in the direction of the second assembly reference plane 33, the side surface C of the light receiving element IC21' is stopped at the position in contact with the pin 61, so that the positioning can be facilitated.

Further, on the first assembly reference plane 32 of the substrate 31,
Since the positioning ridge 35 and the frame members 52, 53, 54 form a rectangular frame body 51 and the frame body 51 is filled with the resin 55 having a light-transmitting property, the light receiving element IC 21 'and The wire 28 can be protected.

In the embodiments described above, the N-type semiconductor substrate 23 and the semiconductor substrate 2 are used as the light receiving element 21.
P having a polarity different from that of the semiconductor substrate 23 formed on
Type light receiving element IC having a structure including the semiconductor layers 24A and 24B
Although 21 'is used, the structure is not limited to this, and for example, an N-type semiconductor layer may be formed on the P-type semiconductor substrate 23 at a fine pitch.

[0027]

According to the optical displacement detecting device of the present invention,
Positioning of the light receiving element can be performed mechanically and easily, and even when the light receiving element is formed by half-cutting from the wafer, the side surface of the light receiving element can be used as an assembly reference plane for assembly.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a general optical displacement detection device.

FIG. 2 is a perspective view showing a light receiving element used in an optical displacement detection device.

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is a perspective view showing another light receiving element used in the optical displacement detection device.

FIG. 5 is a sectional view taken along line VV of FIG. 4;

FIG. 6 is a diagram showing a rotation direction of positioning of the optical displacement detection device.

FIG. 7 is a diagram showing a structure for mechanically positioning a light receiving element.

FIG. 8 is a side view of FIG. 7;

FIG. 9 is a diagram showing how a wafer is half-cut.

FIG. 10 is a diagram showing how half-cut wafers are individually separated.

FIG. 11: Light-receiving element IC obtained by half-cutting
FIG.

FIG. 12 is a plan view showing an embodiment of a light receiving means used in the optical displacement detection device of the present invention.

13 is a sectional view corresponding to line XIII-XIII in FIG.

[Explanation of symbols]

 12 Optical Grating 12A Light Transmitting Section 12B Light Blocking Section 13 Main Scale 16 Illuminating Means 21 Light-Receiving Element 21A, 21B, 21 'Light-Receiving Element IC 23 N-type Semiconductor Base 24A, 24B P-type Semiconductor Layer 25 Photosensitive Band 31 Substrate 32 First Assembly Reference surface 33, 34 Second assembly reference surface 35 Positioning portion 61 pin

Claims (2)

[Claims] 1. A main scale having an optical grating in which light transmitting portions and light blocking portions are alternately arranged at a constant pitch,
Illumination means arranged on one side of this main scale,
In an optical displacement detection device including a light receiving unit arranged on the opposite side of the illumination unit with the main scale interposed therebetween, the light receiving unit is arranged so as to be relatively displaceable so as to face the main scale. A board having a surface facing the scale as a first assembly reference surface, and a pair of second assembly reference surfaces which are fixed to the first assembly reference surface and are perpendicular to the first assembly reference surface and parallel to each other. And a light receiving element having a light receiving surface having a photosensitive band formed at a fine pitch and having a side surface opposite to the light receiving surface fixed to the first assembly reference surface of the substrate, and a side surface of the light receiving element. An optical displacement detection device, comprising: a cylindrical pin disposed between the positioning protrusion and one of the second assembly reference planes so as to be in contact therewith, and in parallel with the second assembly reference plane. apparatus. 2. The optical displacement detection device according to claim 1, wherein the pin has a cylindrical shape having a radius dimension smaller than a thickness dimension of the light receiving element. .