JP3508396B2 - Method of manufacturing bar code reading composite optical device - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a manufacturing method of a bar code reading composite optical device.

[0002]

2. Description of the Related Art Bar code reading systems (hereinafter referred to as "bar code reading systems") are conventionally
It has been assembled using packaged discrete components such as a light source (eg a semiconductor laser) and a photodetector (eg a photodiode). Therefore, this conventional barcode reading system requires a size determined by the size of these components, and there is a limit to miniaturization. Further, in this conventional barcode reading system, it is necessary to adjust the relative position of each component with high accuracy of -10 μm. Furthermore, there is a limit in reliability because the relative position between the parts may change with time after assembly.

Therefore, in order to overcome these drawbacks,
There has been proposed a bar code reading composite optical device (hereinafter also referred to as a “bar code reader composite optical device”) as shown in FIG. 10 in which a laser chip, a prism and the like are hybrid-integrated on a photodiode IC.

As shown in FIG. 10, in this composite optical device for bar code readers, a photodiode IC1 is used.
A prism 102 is mounted on 01 to cover the photodiode PD ′, and a block 103 on which a semiconductor laser 104 is mounted is mounted adjacent to the prism 102. Prism 102
Is a slope 10 inclined by 45 ° with respect to the bottom surface 102a.
With 2b. On this slope 102b, the semiconductor laser 1
A reflection film 105 having a size that is completely included in the spot of the emitted light L ′ from 04 on the inclined surface 102 b is provided.

In the composite optical device for a bar code reader constructed as described above, the emitted light L'from the semiconductor laser 104 is reflected by the reflecting film 105 provided on the inclined surface 102b of the prism 102 and then omitted from the drawing. An image is formed on the barcode to be read by the convergent lens. Then, the signal light from this bar code returns to the composite optical device for a bar code reader via the above-mentioned converging lens, passes through the prism 102, enters the photodiode PD ', and is converted into an electric signal. Thereby, the barcode is read.

[0006]

According to the composite optical device for a bar code reader shown in FIG. 10, it is possible to reduce the size and weight, reduce the position adjustment process, and improve the reliability. The reader composite optical device has the following problems.

That is, at least the photodiode IC 101, the prism 102, the block 103 and the semiconductor laser 104 are required for assembling the composite optical device for a bar code reader shown in FIG. 10, and the number of parts is as many as four. Therefore, there is no doubt that it will be improved compared to the conventional barcode reading system that is assembled using packaged individual parts, but the problem that the relative position adjustment between each part is difficult remains. However, this causes a decrease in yield. Further, although the change over time after assembly is improved as compared with the conventional one, since the number of parts is large, there is concern about thermal reliability or the like at the joint between the parts. Further, generally, in terms of cost, the smaller the number of parts, the more advantageous.

On the other hand, in the conventional composite optical device for a bar code reader shown in FIG. 10, the signal light from the bar code is incident on the inclined surface 102b of the prism 102, and is incident on the photodiode PD 'through the prism 102. Therefore, the size of the opening of the photodiode PD ′ with respect to the signal light from the barcode is determined by the slope 1 of the prism 102.
The size is limited by the size of the reflective film 105 provided on 02b. Therefore, the signal light from the bar code cannot be efficiently incident on the photodiode PD ′, and therefore the signal-to-noise ratio (S / N ratio) of the optical signal is low.

[0009]

Therefore, an object of the present invention is to provide an optical signal
For barcode reading with high S / N ratio
Barco that can manufacture compound optical devices at low cost
To provide a method for manufacturing a composite optical device for reading a code
It is in.

[0011]

To achieve the above object, according to the Invention The, the inventions are little inclined portion with respect to the bottom surface
At least on one side and the part adjacent to this side
A total reflection film is provided on the upper surface of the
The entire permeable membrane is on the upper surface of the part except the contact part.
Use a prism with an almost trapezoidal cross section
A method for manufacturing a composite optical device for reading barcodes.
Then, install multiple prisms on the inclined part of one side of them.
Minutes are almost coplanar with each other and adjacent to each other
The upper surface of one of the pair of prisms and the bottom surface of the other
When placed so that they touch each other, they are almost perpendicular to the plane.
Form a total reflection film by vapor deposition from the direct direction
It is characterized by doing so.

[0012]

[0013]

[0014]

[0015]

[0016]

[0017]

[0018] Oite this inventions, for example, one side of the prism consists of portions inclined relative to the substantially vertical portion and the bottom surface to the bottom surface of the prism.

[0019] Oite to this inventions are, typically, vapor deposition is performed by a sputtering method or a vacuum evaporation method.

[0020]

[0021]

According to this inventions constructed as described above, a plurality of prisms, with respect to the plane in a state where the inclined portion of their one side are arranged to come on substantially the same plane with each other Since the total reflection film is formed by performing vapor deposition from a substantially vertical direction, it is possible to collectively form the total reflection films of these plural prisms by one vapor deposition, and thus the total reflection is performed. The cost required for forming the film can be reduced, and the cost of the barcode reading composite optical device can be reduced.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In all the drawings of the embodiments, the same or corresponding parts are designated by the same reference numerals.

FIG. 1 shows a composite optical device for a bar code reader according to the first embodiment of the present invention. As shown in FIG. 1, in this composite optical device for bar code readers, a photodiode 2 for detecting a signal light is monolithically formed by a diffusion process or the like, and a prism 2 made of optical glass or the like is formed on a photodiode IC1. The chip-shaped semiconductor laser 3 is mounted adjacent to the diode PD, and is mounted adjacent to the prism 2. In this case, the prism 2 is a triangular prism.

The photodiode IC1 is obtained by integrating the photodiode PD, a driving circuit for the semiconductor laser 3 and a reception amplifier circuit (not shown) on a semiconductor substrate such as a Si substrate or a GaAs substrate. is there.

Although not shown, the prism 2 is adhered onto the photodiode IC1 with, for example, an epoxy resin adhesive or a silicone resin adhesive.
Further, the prism 2 has an inclined surface 2b inclined at a predetermined angle with respect to the bottom surface 2a, for example, 45 °. A total reflection film 4 made of, for example, an Al film is provided on the slope 2b.

The semiconductor laser 3 is a photodiode IC.
The semiconductor laser 3 is mounted on a predetermined die pad (not shown) provided on the die 1 by die bonding with, for example, silver paste. As the semiconductor laser 3, for example, GaAs / AlGaAs
A semiconductor laser is used. In this case, the semiconductor laser 3 has its junction (indicated by a broken line in FIG. 1) in order to prevent the emitted light L from the semiconductor laser 3 from being reflected by the surface of the photodiode IC1 and becoming noise light. Are mounted so that they are on the upper side (the side opposite to the photodiode IC1).

According to the first embodiment, the components necessary for assembling the composite optical device for a bar code reader are the photodiode IC1, the prism 2 and the semiconductor laser 3.
Therefore, the number of parts is reduced by at least one as compared with the conventional composite optical device for a bar code reader. Therefore, the cost of the composite optical device for a bar code reader can be reduced, the yield can be improved, and the reliability such as thermal reliability can be improved.

Further, according to the first embodiment, since the signal light SL from the bar code is directly incident on the photodiode PD, the signal light SL from the bar code can be efficiently incident on the photodiode PD '. Therefore, the S / N ratio of the optical signal can be increased.

FIG. 2 shows an example of a bar code reading system constructed by using the composite optical device for bar code reader shown in FIG. As shown in FIG. 2, this bar code reading system includes a bar code reader composite optical device shown in FIG. 1 and a bar code BC on which the emitted light L from the bar code reader composite optical device is to be read. Bifocal lens 11 for forming an image
And an optical system including a mirror 12 such as a polygon mirror. Here, bifocal lens 1
1 includes a first lens portion 11a having a small numerical aperture (NA) and a second lens portion 11b having a large NA.

In this case, the composite optical device for a bar code reader, which is composed of the photodiode IC1, the prism 2 and the semiconductor laser 3, is housed in the package 13.
As the package 13, for example, a resin mold package, a ceramic package, a metal package, an acrylic resin package, or the like can be used. Reference numeral 13a indicates a lid portion of the package 13. The lid portion 13a is formed of a transparent material so that the emitted light L from the semiconductor laser 3 and the signal light SL from the barcode BC can be transmitted.

Next, the operation of the bar code reading system shown in FIG. 2 configured as described above will be described.

The emitted light L from the semiconductor laser 3 is
After being reflected by the total reflection film 4 (see FIG. 1) on the inclined surface 2b of the prism 2 and bent at a right angle, the light passes through the lid portion 13a of the package 13 and is emitted upward in FIG. 2, that is, toward the bifocal lens 11 side. To be done. At this time, since all the outgoing light L is reflected by the total reflection film 4 in this way, stray light does not occur. The emitted light L is transmitted to the bifocal lens 1
After passing through the first first lens unit 11a, the image is reflected by the mirror 12 and is imaged on the barcode BC to be read.

The signal light SL from the bar code BC is reflected by the mirror 12 and then the bifocal lens 11
This bifocal lens 1
It is converged through the first second lens portion 11b, further passes through the lid portion 13a of the package 13, and enters the photodiode PD on the photodiode IC1. At this time, the light incident on the photodiode PD generates a current corresponding to approximately (light intensity) × (area of the photodiode PD). This photocurrent is converted into a voltage by the current-voltage conversion circuit of the reception amplification circuit provided in the photodiode IC1, and then subjected to necessary calculation and amplification, and output as a voltage signal. in this case,
The amount of light incident on the photodiode PD varies depending on the reflectance on the barcode BC, and thus the voltage signal also varies, so that the barcode BC can be recognized by this voltage signal. In this way, the barcode BC is read.

FIG. 3 shows another example of the bar code reading system constructed by using the composite optical device for bar code reader shown in FIG. As shown in FIG. 3, this barcode reading system is a bifocal lens 1 in the barcode reading system shown in FIG.
The barcode reading system has the same configuration as that of the barcode reading system shown in FIG. 2 except that the hologram 14 and the converging lens 15 are used instead of 1, and the operation is also the same. In this case, the signal light SL from the barcode BC is
The hologram 14 is bent in its traveling direction and is incident on the photodiode PD on the photodiode IC1.

FIG. 4 shows a composite optical device for a bar code reader according to the second embodiment of the present invention. In the composite optical device for a bar code reader according to the first embodiment described above, the semiconductor laser 3 is mounted on the photodiode IC1 so that its junction surface faces upward. In the composite optical device for a code reader, the semiconductor laser 3 is mounted on the photodiode IC1 with an adhesive 16 made of, for example, silver paste so that its bonding surface faces downward. In this case, in order to prevent the emitted light L from the semiconductor laser 3 from being reflected by the surface of the photodiode IC1 and becoming noise light, the photo in the portion in front of the light emitting point on the front end face of the semiconductor laser 3 is prevented. The diode IC1 is provided with a step 1a having a side wall substantially perpendicular to the main surface of the photodiode IC1 by etching or the like. The prism 2 is mounted below the step 1a.

Other than the above of the second embodiment,
The description is omitted because it is the same as the first embodiment. Also in the second embodiment, the same advantages as in the first embodiment can be obtained.

FIG. 5 shows a composite optical device for a bar code reader according to the third embodiment of the present invention. In the composite optical device for a bar code reader according to the second embodiment described above, the side wall of the step 1a provided in the photodiode IC1 in the portion in front of the light emitting point on the front end surface of the semiconductor laser 3 is the photodiode IC1. Is substantially perpendicular to the main surface of the photodiode IC1, the side wall of the step 1a is inclined with respect to the main surface of the photodiode IC1 in the composite optical device for a bar code reader according to the third embodiment. . The prism 2 is mounted below the step 1a in a state in which one side of the bottom surface 2a contacts the inclined side wall and is positioned.

Here, the inclined side wall of the step 1a is
For example, it can be formed using anisotropic etching. Specifically, when the photodiode IC1 is formed by using a semiconductor substrate such as a Si substrate or a GaAs substrate having a (100) plane orientation, this inclined sidewall is anisotropically etched. It can be formed by forming a (111) plane.

Other than the above of the third embodiment,
The description is omitted because it is the same as the first embodiment. According to the third embodiment, in addition to the same advantages as in the first embodiment, the inclined side wall of the step 1a serves as a reference for mounting the prism 2, so that the prism 2 can be easily mounted. Therefore, it is possible to obtain an advantage that mounting accuracy is increased.

FIG. 6 shows a bar code reading system constructed by using a composite optical device for bar code readers according to a fourth embodiment of the present invention. In the composite optical device for barcode reader according to the first embodiment, the prism 2 is a triangular prism, whereas in the composite optical device for barcode reader according to the fourth embodiment, the prism 2 is It has a shape in which a portion near one side of a rectangular parallelepiped is cut off obliquely. In this case, the side surface of the prism 2 on the semiconductor laser 3 side is composed of an end surface 2c perpendicular to the bottom surface 2a and an inclined surface 2b continuous with the end surface 2c. A total reflection film 4 is provided on the slope 2b. Further, a total transmission film (non-reflection film) 5 is provided on the upper surface 2d of the prism 2. In this case, the prism 2 is mounted so as to cover the photodiode PD. On the other hand, the semiconductor laser 3 is placed on a block 6 made of, for example, a Si chip.

The roles of the hologram 14, the converging lens 15 and the mirror 2 in this bar code reading system are the same as those in the bar code reading system shown in FIG.

Next, the operation of the bar code reading system shown in FIG. 6 configured as described above will be described.

The emitted light L from the semiconductor laser 3 is reflected by the total reflection film 4 formed on the inclined surface 2a of the prism 2 and bent vertically, then passes through the hologram 14 and the converging lens 15, and is further reflected by the mirror 2. It is reflected and imaged on the barcode BC.

After passing through the converging lens 15, the signal light SL from the bar code BC is bent in its traveling direction through the hologram 14, passes through the total transmission film 5 and the prism 2, and passes through the photo diode IC1. Diode PD
And is converted into an electric signal. By this, the first
In the same manner as described in the above embodiment, the barcode BC
Is read.

According to the fourth embodiment, the prism 2
Since the entire upper surface 2d of the above is an opening for the photodiode PD of the signal light SL from the barcode BC, this opening can be made sufficiently large. Therefore, the signal light SL from the bar code BC can be efficiently incident on the photodiode PD, and thus the S / of the optical signal
The N ratio can be increased.

Next explained is a composite optical device for a bar code reader according to the fifth embodiment of the invention.

In the composite optical device for a bar code reader according to the fourth embodiment described above, the upper surface 2d of the prism 2 is used.
Is formed so that the signal light SL from the bar code BC is incident on the photodiode PD through the entire transparent film 5, and the entire upper surface 2d of the prism 2 is formed by the photo. Stray light increases due to the opening for the diode PD. Therefore, this fifth
In the composite optical device for a bar code reader according to the embodiment of the present invention, as a countermeasure against this stray light, as shown in FIG. The total reflection film 4 is also provided so as to extend.

Except for the above, the fifth embodiment is the same as the fourth embodiment, and the description thereof will be omitted.

When the amount of stray light was measured when the countermeasure against stray light was taken and when the countermeasure against stray light was not taken, the amount of stray light when the countermeasure against stray light was taken was about 1 of the amount of stray light when the countermeasure against stray light was not taken. It was / 6. From this, it was confirmed that the amount of stray light was significantly reduced by taking measures against stray light.

As described above, according to the fifth embodiment, in addition to the same advantages as the fourth embodiment, the prism 2
Since the total reflection film 4 extends on the upper surface 2d of the portion adjacent to the inclined surface 2b, the amount of stray light can be significantly reduced.

In the above fifth embodiment, the slope 2b of the prism 2 and the upper surface 2d of the portion adjacent to the slope 2b.
The total reflection film 4 provided on the end face 2c can be formed, for example, as follows. That is, as shown in FIG. 8, the plurality of prisms 2 have their slopes 2b located in the same plane, and one bottom surface 2a and the other top surface 2b of the pair of prisms 2 adjacent to each other contact each other. With such an arrangement, a metal such as Al is vapor-deposited by a sputtering method, a vacuum vapor deposition method, or the like from a direction substantially perpendicular to the slopes 2a. In this case, since the upper surface 2d and the end surface 2c of the prism 2 form an angle of about 45 ° with respect to the vapor deposition direction, a vapor deposition method having little angle dependency is used, and the angle dependency in the characteristics of the total reflection film 4 is used. It is desirable to reduce the sex.

According to the method of forming the total reflection film 4 as described above, the total reflection films 4 of the plurality of prisms 2 can be collectively formed by one vapor deposition. Therefore, the cost required to form the total reflection film 4 can be significantly reduced, and the manufacturing cost of the composite optical device for a bar code reader can be reduced.

FIG. 9 shows a typical stray light path in a composite optical device for a bar code reader. As shown in FIG.
The emitted light L from the semiconductor laser 3 reflected by the upper portion of the slope 2b of the prism 2 has a relatively large incident angle θ.
Then, the light enters the lid portion 13a of the package 13. The transmittance of the lid portion 13a depends on the incident angle, and the reflectance increases as the incident angle increases. Therefore, when light enters at such a large incident angle θ, a part of the incident light Returns to the composite optical device for barcode reader. When this return light enters the photodiode PD, it causes an increase in stray light. In order to prevent this, the lid portion 13a, which has been designed to have a transmittance of 100% when the incident angle is 0 °, has a transmittance of 100% when incident at an incident angle θ. By designing as described above, the reflectance of the emitted light L reflected on the upper portion of the inclined surface 2b of the prism 2 may be reduced to suppress the return light to the composite optical device for a bar code reader.

By doing so, the lid portion 13
The light reflected by a can be reduced, and stray light can be reduced. As a result, the S / N ratio of the optical signal of the composite optical device for barcode reader can be sufficiently increased.

The embodiments of the present invention have been specifically described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made based on the technical idea of the present invention.

For example, in the above-mentioned fourth embodiment,
Instead of the hologram 14 and the converging lens 14, the first
Of the bifocal lens 11 as in the embodiment of FIG.
May be used. Further, in the above-described fourth embodiment, the prism 2 having a substantially trapezoidal cross-sectional shape is used, but as the prism 2, a triangular prism similar to that used in the first embodiment is used. Good. In this case, the signal light SL from the barcode BC can be directly incident on the photodiode PD without passing through the prism 2.

[0058]

As described above , according to the method of manufacturing the composite optical device for reading a bar code of the present invention ,
A plurality of prisms are arranged so that the inclined portions of one side face each other.
In a state where they are placed on almost the same plane
By vapor deposition from a direction almost perpendicular to
Since I am trying to form a spray film,
Rhythm total reflection film is formed collectively by one deposition.
Therefore, the cost required to form the total reflection film can be reduced.
It is possible to reduce
It is possible to reduce the cost of the composite optical device for use.

[0059]

[0060]

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a composite optical device for a bar code reader according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing an example of a barcode reading system using the composite optical device for barcode reader according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram showing another example of a barcode reading system using the composite optical device for barcode reader according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram showing a composite optical device for a bar code reader according to a second embodiment of the present invention.

FIG. 5 is a schematic diagram showing a composite optical device for a bar code reader according to a third embodiment of the present invention.

FIG. 6 is a schematic diagram showing an example of a barcode reading system using a composite optical device for barcode reader according to a fourth embodiment of the present invention.

FIG. 7 is a schematic diagram showing a composite optical device for a bar code reader according to a fifth embodiment of the present invention.

FIG. 8 is a schematic diagram for explaining a method of forming a total reflection film provided on a prism in the composite optical device for a bar code reader according to the fifth embodiment of the present invention.

FIG. 9 is a schematic diagram for explaining a typical stray light path in the composite optical device for a barcode reader according to the fourth embodiment or the fifth embodiment of the present invention.

FIG. 10 is a schematic diagram showing a conventional composite optical device for a bar code reader.

[Explanation of symbols]

1 ... Photodiode IC, 2 ... Prism, 2
b ... Slope, 2d ... Top surface, 3 ... Semiconductor laser, 4 ... Total reflection film, 5 ... Total transmission film, PD ...
Photodiode, L ... Emitted light, SL ... Signal light

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Claims (3)

(57) [Claims] 1. The number of parts inclined with respect to the bottom surface is reduced.
In one side that has both and in the part adjacent to this one side
A total reflection film is provided on the upper surface and on the one side surface.
Totally permeable membrane on the upper surface of the part except the adjacent part
A prism with a substantially trapezoidal cross-section
In the manufacturing method of the compound optical device for barcode reading used
There are multiple prisms, the tilt of one of them on one side
Are located substantially on the same plane with each other and
The upper surface of one of the pair of prisms adjacent to
The above bottom surface of the
By performing vapor deposition from a direction almost perpendicular to the plane
A bar characterized in that the above total reflection film is formed.
-Method for manufacturing a compound optical device for reading a code. 2. The prism is provided with the one side surface of the prism.
On the part of the
2. A portion which is inclined with respect to the above.
A method for manufacturing the composite optical device for reading a barcode according to claim 1. 3. A sputtering method or a vacuum deposition method
2. The vapor deposition is performed according to claim 1.
A method for manufacturing the composite optical device for reading a barcode according to claim 1.