JP2003005120A - Optical deflecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical deflecting device which can be made small-sized and have high durabilty and are flexibly adaptive to various specifications. SOLUTION: The optical deflecting device 31 is provided with a light emitting element 35, a convex mirror 43 which reflects the light emitted by the light emitting element 35, a driving means 41 which displaces a displacement surface 57 corresponding to an input voltage while the convex mirror 43 is fixed and held on the displacement surface 57, a light projection lens 39 which passes the light reflected by the convex mirror 43, a photodetection lens 45 which converges return light of the light passing through the projection lens 39 to irradiates an object of irradiation, and a photodetecting element 47 which photodetects and converts the return light passed through the photodetection lens 45 into electricity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical deflector for temporally controlling the angle of a light beam propagation direction, and more particularly,
The present invention relates to an improved technique that enables downsizing of a device by simplifying a mirror moving mechanism.

[0002]

2. Description of the Related Art In recent years, in many stores and factories, a bar code representing digital information is attached to an article, and the information is optically scanned to read the information, thereby controlling the sales of the article and the production of the article. And so on. In general, a barcode of this type irradiates the barcode with light and photoelectrically converts the intensity of the reflected light to read information from the combination of the detection signals.

That is, as shown in the conceptual diagram of FIG. 5, the light from the light emitting element 1 is narrowed down by the light emitting lens 3, this light is reflected by the mirror 7 of the scan mirror 5, and is reflected by the bar code 9 to be irradiated. Irradiate. Since the light is emitted over the entire area of the barcode 9, the mirror 7 is swung. The rocking is performed by inserting the magnet 11 attached to the mirror 7 into the drive coil 13 and causing a positive and negative current to flow through the drive coil 13 at a constant cycle, for example, to attract and repel the magnet 11 to the drive coil 13 and rock. The mirror 7 is swung about the fulcrum 15 as a pivot.

On the other hand, the light radiated on the surface of the bar code 9 returns to the mirror 7 again due to a change in the amount of light due to the black and white of the bar code while being irregularly reflected, and the light reflected there is condensed by the condenser lens 17 and the light receiving element 19 is received. To electrically convert the change in the light amount and output it. In order to improve the reading accuracy,
A bandpass filter (BPF) is provided on the front surface of the light receiving element 19.
21 is provided to prevent the collection of unnecessary light other than the light emission frequency.

An optical deflector for reading a bar code (so-called beam scanner) shown in FIG. 6 is provided as a device of such a reading method. As shown in the drawing, the configuration of this light deflecting device includes a light emitting mechanism A in which a light emitting element 1 and a light emitting lens 3 are housed in a housing 25, and a light receiving element 1.
The light receiving mechanism B having the light receiving lens 9 and the light receiving lens 17 and the BPF 21 housed in the housing 27 is mounted on the substrate 29. Electrical connection within each housing 25, 27 is performed by wire bonding or the like. The mirror 7 of the scan mirror 5 is arranged to be swingable around the swing fulcrum 15. The light emitting mechanism A, the light receiving mechanism B, and the scan mirror 5 are housed in a frame (not shown) to form a bar code reading optical deflector.

Further, as a mechanism for irradiating light over the entire area of the bar code 9, there is a mechanism using a rotating mirror in addition to the above-mentioned swing type scan mirror. This rotating mirror type optical deflector deflects the light beam by reflecting the light beam on the surface of a polygonal mirror called a polygon mirror and rotating the polygonal mirror around a central axis at high speed by a motor. , The light spot can be linearly scanned repeatedly at a constant speed.

[0007]

However, the above-mentioned conventional optical deflector includes a scan mirror that swings a mirror around a swing axis and a polygon mirror that rotates a polygonal prism around a central axis by a motor. Since it is used, a rotary shaft, a coil, a magnet, a motor, etc. are required, the number of parts is large, the space occupied by these mirror mechanisms is large, and there is a limit to downsizing the entire device. In addition, since a wear member such as a rotary shaft and a bearing that supports the rotary shaft is used, the durability is low, and the non-fixed movable portion is included, which is weak against external impact. Further, in recent years, the specifications of the optical deflecting device tend to be diversified in response to various types of barcodes, but in the optical deflecting device using a scan mirror, an additional function of swing angle control using an angle sensor or the like is added. Therefore, in a light deflecting device using a polygon mirror, a polygonal mirror must be designed for each specification, and it is difficult for any of the light deflecting devices to flexibly meet various specifications, and the versatility is low. There was a flaw. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical deflecting device that can achieve miniaturization, high durability, and flexibly comply with various specifications. .

[0008]

According to a first aspect of the present invention, there is provided a light deflecting device comprising: a light emitting element; a convex mirror for reflecting light emitted from the light emitting element;
Driving means for fixedly holding the convex mirror on the displacement surface and displacing the displacement surface in response to an input voltage, a light projecting lens for passing the light reflected by the convex mirror, and a light projecting lens for passing through the light projecting lens. It is characterized by comprising a light receiving lens that focuses return light of the light that has irradiated the irradiation target, and a light receiving element that receives the return light that has passed through the light receiving lens and converts it into electricity.

In this optical deflector, the light emitted from the light emitting element is applied to the convex mirror and reflected, so that a large displacement angle of the light beam can be obtained with a small displacement of the convex mirror. As a result, it is possible to use a driving means such as a piezoelectric element that reciprocates the displacement surface by inputting a voltage, and the components of the rotating shaft, coil, and magnet, which are required in the conventional swing mechanism, are not required. Therefore, the size of the device can be greatly reduced. Further, since the rotating shaft and bearings supporting the rotating shaft are eliminated, durability is improved and all the parts can be fixed and assembled, so that a robust movable mechanism that is resistant to impact can be realized. Furthermore, depending on the input voltage to the driving means,
Since the displacement speed and the displacement amount of the displacement surface can be changed, the deflection frequency and the swing angle of the light beam can be easily controlled.

The optical deflector according to a second aspect of the invention is characterized in that the convex mirror is a convex mirror using at least a part of the outer peripheral surface of the cylinder.

In this optical deflecting device, the convex mirror can be easily manufactured by using the convex mirror that uses at least a part of the outer peripheral surface of the cylinder. That is, a convex mirror can be easily manufactured by forming a mirror surface on the outer surface of a cylindrical body or an inner surface of a transparent cylindrical body, or by forming a mirror surface on the outer surface of a cylinder or a round bar.

According to a third aspect of the present invention, there is provided an optical deflector in which the driving means is a piezoelectric element.

In this optical deflecting device, when a voltage is applied to the piezoelectric element which is the driving means, strain is generated in the piezoelectric element, and the position of the displacement surface moves, that is, is displaced by the strain. Therefore, the position of the convex mirror fixedly held on the displacement surface relative to the light emitting element changes, and the reflection angle of the light beam repeatedly changes within the displacement range. This allows the deflection of the light beam.

An optical deflector according to a fourth aspect is characterized in that a convex curved surface is formed on the displacement surface of the piezoelectric element, and metal is deposited on the convex curved surface to form the convex mirror.

In this optical deflector, a convex curved surface is formed on the displacement surface of the piezoelectric element, and metal is deposited on the convex curved surface to obtain a convex mirror. The convex curved surface formed on the displacement surface can be formed by the piezoelectric element material itself or by adhering another molding material. With such an integrally formed structure, it is possible to further reduce the size and make it more robust than when a separate convex mirror is bonded.

According to a fifth aspect of the present invention, there is provided the optical deflector according to the fifth aspect, wherein the light projecting lens has a lens surface that aberrates the non-circular light spot image reflected by the convex mirror into the original circular light spot image. Is characterized by.

In this optical deflecting device, when the light emitted from the light emitting element becomes a light beam and is incident on the convex mirror and then reflected, the light spot image formed by the light beam changes from circular to non-circular due to distortion. The light projecting lens reversely aberrates the light beam forming the non-circular light spot image (that is, corrects the aberration), so that the non-circular light spot image becomes the original circular light spot image.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of an optical deflecting device according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a sectional view of an optical deflecting device according to the present invention, and FIG.
-X arrow view, FIG. 3 is an enlarged perspective view of the convex mirror, and FIG. 4 is an explanatory view showing the shape of the light spot image before and after the convex mirror and after the projection lens for each swing angle of the light beam. .

The light deflecting device 31 according to the present embodiment includes a light emitting element 35 in a package 33 formed of a resin material.
The first and second light projecting lenses 37 and 39, the driving means (piezoelectric element) 41, the convex mirror (cylindrical mirror) 43, the light receiving lens 45, and the light receiving element 47.

The package 33 has a rectangular parallelepiped accommodating space (cavity) 49 therein. Cavity 4
A light emitting element 35 is attached to one inner surface 51 of the light source 9, and the light emitting element 35 emits the light beam L in a direction perpendicular to the inner surface 51.
b is emitted. The light emitting element 35 is located at the front of the light beam emitting direction, and the first light projecting lens 3 which makes the emitted light a stop light beam Lb.
Have 7. In the light emitting element 35, a plurality of leads 53, which are respectively connected to the internal electrodes, extend through the wall portion of the package 33 to the outside.

The piezoelectric element 41 is fixed to another inner surface 55 orthogonal to the inner surface 51 to which the light emitting element 35 is fixed. The piezoelectric element 41 also has a plurality of leads 53 connected to the respective electrodes and led out to the outside through the wall portion of the package 33. The piezoelectric element 41 is formed in a plate shape and fixes the lower surface to the inner surface 55. The surface of the piezoelectric element 41 parallel to the lower surface serves as the displacement surface 57. In the piezoelectric element 41, opposite electrodes (not shown) are provided in parallel with the lower surface and the displacement surface 57 sandwiched therebetween.
By applying a predetermined voltage between the opposing electrodes, the applied voltage is converted as a change in the distance between the opposing electrodes. That is, the piezoelectric element 41 has the displacement surface 57 corresponding to the applied voltage.
Is a linear motion type actuator that translates (displaces) in a direction perpendicular to the inner surface 55.

As the piezoelectric element 41, barium titanate, which has high mechanical strength, and PZT, which is a similar material thereof, are used.
A group of magnetic substances such as (lead titan zirconate), a highly sensitive Rochelle salt, and the like can be used.

In the present embodiment, the case where the driving means is the piezoelectric element 41 will be described as an example, but the optical deflector according to the present invention serves as the driving means and displaces the displacement surface in correspondence with the input voltage. A flexible thin film (diaphragm) that can be used may be used. In this driving means, a diaphragm having a high resistance layer is provided on a substrate with a spacer therebetween with a gap, and a voltage is applied between the diaphragm and the substrate to electrostatically induce induction in the high resistance layer of the diaphragm. The cloning force acting between the applied charge and the electrodes of the substrate allows the diaphragm to be displaced with respect to the substrate.

On the displacement surface 57 of the piezoelectric element 41, at least a part of the outer peripheral surface is a reflecting surface, which is a separate cylindrical mirror 4.
3 is fixed by adhesion. The cylindrical mirror 43 may be an anti-cylinder obtained by cutting the cylinder in one or two cross sections parallel to the central axis, or a quarter cylinder. In the present embodiment, the case where the convex mirror is the cylindrical mirror 43 is described as an example, but the convex mirror has a cross-sectional shape orthogonal to the central axis of the cylindrical body, such as a circle other than a perfect circle, for example, an ellipse, an oval, or the like. It may have a reflecting surface formed of an arbitrary convex curved surface. When the convex mirror is the cylindrical mirror 43 as in the present embodiment, by forming a mirror surface on the outer surface of the cylindrical body or the inner surface of the transparent cylindrical body, or by forming the mirror surface on the outer surface of the cylinder or the round bar, A convex mirror can be easily manufactured.

The cylindrical mirror 43 has a central axis parallel to the inner surface 55 and a light beam Lb emitted from the light emitting element 35.
And is fixed to the displacement surface 57 in a direction in which the central axes are orthogonal to each other.
As shown in FIG. 3, the light beam Lb emitted from the light emitting element 35 is incident on the reflection surface formed on the outer peripheral surface of the cylindrical mirror 43 and is symmetrical with respect to the normal line at the incident position (that is, the incident angle Reflection angle is the same).

The piezoelectric element 41 displaces the displacement surface 57 according to the applied voltage, and reciprocates the cylindrical mirror 43 in the direction perpendicular to the inner surface 55. Therefore, the incident point of the light beam Lb on the cylindrical mirror 43 moves. That is, the light beam Lb reciprocates in the arc direction on the reflecting surface of the cylindrical mirror 43. Thereby, the light emitting element 35
And the relative position of the cylindrical mirror 43 repeatedly change,
The light beam Lb can be deflected.

In FIG. 1, the radius of the cylindrical mirror 43 is 2 m.
m, the displacement amounts a, b, and c of the cylindrical mirror 43 and the optical paths A, B, and C of the light beam Lb when the swing angle of the light beam Lb is 50 degrees. The optical path of A is when the light beam Lb emitted from the light emitting element 35 has an incident angle of 45 degrees. The optical path of B is when the cylindrical mirror 43 moves forward by the displacement amount i (moves downward in FIG. 1) and the light beam Lb emitted from the light emitting element 35 has an incident angle of 32.5 degrees. In the optical path of C, the light beam Lb incident from the light emitting element 35 due to the cylindrical mirror 43 retreating (moving upward in FIG. 1) due to the displacement b
Represents an incident angle of 57.5 degrees. The displacement amounts a and b are the cylindrical mirror 4 for each reflection angle.
3 represents the relative movement amount, i = 0.2726 mm, b =
It is 0.3396 mm and Ha = i + b = 0.6122 mm.

Therefore, the light beam Lb from the light emitting element 35 changes the displacement of the cylindrical mirror 43 by c = 0.6122.
If it is mm, it can be swung at an angle of 50 degrees. The cylindrical mirror 43 has a characteristic that the swing angle with respect to the displacement amount increases as the light beam Lb approaches the outer circumference. In the figure, a, b, and c indicate normal lines at the respective reflection points.

The package 33 has an opening 61 on one side surface 59 for irradiating the light beam Lb reflected by the cylindrical mirror 43 to the outside. The second light projecting lens 39 is fitted in the opening 61. The light emitted from the light emitting element 35 becomes a light beam Lb, enters the cylindrical mirror 43, and is then reflected. At this time, the light spot image formed by the light beam Lb changes from a circular shape to a non-circular shape (substantially elliptical) due to distortion, as shown in FIG. The second light projecting lens 39 has a lens surface that makes the original circular light spot image by performing reverse aberration (that is, correcting the aberration) on the light beam that forms this non-circular light spot image. .

The package 33 has an opening 6 on one side surface 59.
1 has an opening 63 for receiving light. The light receiving lens 45 is fitted in the opening 63. The light receiving lens 45 focuses the return light of the light beam Lb that irradiates the barcode to be irradiated and captures it in the package 33. A light receiving element 47 is internally provided behind the light receiving lens 45 inside the package 33. The light receiving element 47 includes a plurality of leads 53, which are respectively connected to the internal electrodes, in the package 3
It penetrates through the wall portion 3 and is led to the outside. Light receiving element 47
Photoelectrically converts the return light focused by the light receiving lens 45 and sends it to the lead 53 as an output signal.

The optical deflector 31 connects each of the leads 53 to a control circuit (not shown). The control circuit controls the light emitting element 35, the piezoelectric element 41, and the light receiving element 47, respectively, and operates to transmit and receive control signals and detection signals to and from the host computer.

In the optical deflector 31 having the above structure,
When the light emitting element 35 emits light by a control circuit (not shown), the light is focused by the first light projecting lens 37 and reflected by the cylindrical mirror 43. The cylindrical mirror 43 moves the irradiation point of the light beam Lb by the reciprocating linear movement of the displacement surface 57 of the piezoelectric element 41, and deflects the light beam Lb at a predetermined swing angle.

Light beam Lb reflected by the cylindrical mirror 43
Passes through the second light projecting lens 39 to correct the distorted light spot image and irradiate it on a bar code (not shown). The deflected light beam Lb irradiates or scans the entire area of the barcode.

The light radiated to the bar code surface enters the light receiving lens 45 while being diffusely reflected while the light quantity of the bar code changes in black and white, and then converges and enters the light receiving element 47. The light receiving element 47 photoelectrically converts this light and outputs the barcode pattern as an electrical signal to the lead 53. This output signal is sent to a computer (not shown) for processing, and the bar code information is decoded.

As described above, according to the above-mentioned optical deflector 31, since the light emitted from the light emitting element 35 is applied to the cylindrical mirror 43 and reflected, the light beam Lb can be increased by a small displacement of the cylindrical mirror 43. Can be rocked. As a result, it is possible to use the piezoelectric element 41 that inputs a voltage and finely reciprocates the displacement surface 57, and the components of the rotating shaft, the coil, and the magnet, which are required in the conventional swing mechanism, are not required, and the device can be used. It can be miniaturized. Also, since the wear parts such as the rotating shaft and the bearings that support it are eliminated,
Since the durability is increased and all parts can be fixed, a robust movable mechanism that is resistant to impacts can be realized. Further, since the displacement speed and the displacement amount of the displacement surface 57 can be changed according to the input voltage to the piezoelectric element 41, the deflection frequency and the swing angle of the light beam Lb can be easily controlled.

The cylindrical mirror 43 described above has been described as an example in which a separate member is adhered and fixed to the displacement surface 57, but the cylindrical mirror 43 has a convex curved surface on the displacement surface 57 of the piezoelectric element 41. The convex mirror may be formed by depositing metal on the convex curved surface. The convex curved surface formed on the displacement surface can be formed by the piezoelectric element material itself or by adhering another molding material. By using such a convex mirror integrated with driving means, it is possible to further reduce the size and make it more robust than the structure in which a separate cylindrical mirror 43 is bonded.

[0037]

As described in detail above, according to the optical deflecting device of the present invention, the light emitted from the light emitting element is applied to the convex mirror to be reflected, so that a small displacement of the convex mirror causes the light beam to largely fluctuate. Can be moved. This allows
It is possible to use driving means such as a piezoelectric element that makes a fine movement back and forth on the displacement surface by inputting a voltage, and the components of the rotating shaft, coil, and magnet, which were required in the conventional swing mechanism, are no longer required, and the device can be greatly expanded. It can be miniaturized. Further, since the rotating shaft and the bearings that support the rotating shaft are eliminated, durability can be improved and all parts can be fixed, so that a robust movable mechanism can be obtained.
Further, since the displacement speed and the displacement amount can be changed by the input voltage to the driving means, the deflection frequency and the swing angle of the light beam can be easily controlled, which enables flexible correspondence to various specifications and versatility. Can be increased.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical deflecting device according to the present invention.

FIG. 2 is a view on arrow XX in FIG.

FIG. 3 is an enlarged perspective view of a convex mirror.

FIG. 4 is an explanatory diagram showing the shape of a light spot image before and after a convex mirror and after a light projecting lens for each swing angle of a light beam.

FIG. 5 is a conceptual diagram illustrating a conventional optical reading method.

FIG. 6 is a cross-sectional view of a conventional bar code reading optical deflector.

[Explanation of symbols]

31 ... Optical deflecting device, 35 ... Light emitting element, 39 ... Second light projecting lens (light projecting lens), 41 ... Piezoelectric element (driving means), 4
3 ... Cylindrical mirror (convex mirror), 45 ... Light receiving lens, 47
... Light receiving element, 57 ... Displacement surface

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shigeru Niizawa             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation F term (reference) 2H045 AC01 BA18 DA31                 5B072 AA03 CC21 CC24 LL01 LL07                       LL11 LL18

Claims (5)

[Claims] 1. A light emitting element, a convex mirror for reflecting light emitted from the light emitting element, driving means for fixing and holding the convex mirror on a displacement surface and displacing the displacement surface in response to an input voltage, and the convex mirror. A light projecting lens that passes the light reflected by the light receiving lens, a light receiving lens that focuses the return light of the light that has passed through the light projecting lens and illuminates the irradiation target, and a light receiving lens that receives the return light that has passed through the light receiving lens. An optical deflector comprising: a light receiving element for converting into electricity. 2. The convex mirror is a convex mirror using at least a part of a cylindrical outer peripheral surface.
The optical deflector described. 3. The optical deflector according to claim 1, wherein the driving means is a piezoelectric element. 4. The optical deflector according to claim 1, wherein a convex curved surface is formed on the displacement surface of the piezoelectric element, and metal is deposited on the convex curved surface to form the convex mirror. 5. The light projecting lens has a lens surface that aberrates a light spot image that is non-circular by being reflected by the convex mirror into an original circular light spot image. 2. The optical deflector according to item 2.