JP2003331213A - Optical information reading device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To read excellently even a reading object having a transparent protective layer on the surface, to suppress enlargement, and to use effectively illumination light from a light source. <P>SOLUTION: An illumination optical system 3, a light receiving sensor 4 and an imaging optical system 5 are provided in a case 1 having a reading port 1a on the tip part lower face. The imaging optical system 5 comprises a first optical part 6 and a second optical part 7 comprising a convex lens respectively, and constitutes a telecentric optical system wherein a visual field is not widened. The illumination optical system 3 is constituted from a plurality of LED's 8 and a light guide 9 for guiding illumination light from the LED's 8 and irradiating the reading object 2 therewith through the reading port 1a. The light guide 9 is constituted by providing integrally light guide regions 9b bent perpendicularly at right-and-left side parts of a rectangular plate-shaped light-emitting region 9a arranged in parallel with the reading port 1a, and a plurality of spotted reflection parts 11 are provided on the surface on the imaging optical system 5 side of the light-emitting region 9a. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information reader for reading information codes such as two-dimensional codes and bar codes.

[0002]

An optical information reader of this kind, for example, a handy type two-dimensional code reader, has a plurality of hand-held cases each having a rectangular reading opening at its tip. An illumination unit including an LED and an illumination lens arranged in front of the LED, a light receiving sensor such as a CCD area sensor, and an image forming lens for forming an image of an object to be read on the light receiving sensor are arranged. .

With this, the reading operation is performed in a state where the reading opening is brought close to the reading target (label or the like) on which a two-dimensional code such as a QR code is recorded, so that the reading is performed from the illumination section through the reading opening. Illumination light is applied to an object, the reflected light is incident from the reading port, and is received by the light receiving sensor via the imaging lens, so that the two-dimensional code is read.

By the way, in the conventional optical information reader of this type, a paper (label) on which an information code is printed is printed.
It was common to read
For example, a liquid crystal display device (L
The usage (system) of reading the information code displayed on the screen of (CD) has been considered. However, when the LCD screen is to be read, a transparent protective layer (glass or plastic) is provided on the surface of the LCD screen, so that the illumination light from the illumination unit is reflected on the protective layer, and from that portion. Since the reflected light is too strong, it may not be possible to read the information code accurately.

Therefore, the following proposals have been made to deal with the case where such an LCD screen is to be read. That is, there is a configuration in which the illumination unit is a surface light source including LEDs and a diffusion plate, is arranged at a position outside the reading field of the imaging optical system, and the surface light source irradiates the reading target with illumination light in an oblique direction. It is considered. Further, by combining the surface light source and the half mirror as described above, the light from the surface light source is reflected by the half mirror to illuminate the reading object vertically with the illumination light, and the reflected light is transmitted through the half mirror and received. A configuration is also considered.

However, in the former case where the surface light source is provided, there is a problem that the device becomes large. At this time, if a general reduction optical system is adopted as the image forming optical system, the area light source must be made large, and the size of the apparatus will be further increased. Even if the latter half mirror is used, there is a problem that the device becomes larger.

The present invention has been made in view of the above circumstances, and an object thereof is to enable good reading even for an object to be read having a transparent protective layer on the surface thereof, and to suppress the increase in size. It is to provide an optical information reading device capable of performing the above.

[0008]

In order to achieve the above object, an optical information reading device of the present invention has an illumination optical system located closer to a reading target than an imaging optical system and a field of view of the imaging optical system. A light guide body having a light emitting area covering the whole is provided, and the light guide body guides the illumination light from the illumination light source and irradiates the reading object from the light emitting area.
The image forming optical system is configured to form an image on the light receiving sensor, which is reflected by the reading target and transmitted through the light emitting region of the light guide body (the invention of claim 1).

According to this, it is possible to irradiate the reading light from the light emitting region of the light guide body, which is a so-called planar light source, almost vertically to the reading object, and an LCD having a transparent protective layer on the surface. Even if it is a target of reading, good reading is possible. Further, since the light emitting area of the light guide is provided within the field of view of the imaging optical system, the illumination optical system can be made more compact than when the surface light source is provided outside the field of view of the imaging optical system. It is possible to dispose them, and it is possible to suppress the size increase of the device. Further, the device can be made compact as compared with the case where the half mirror is adopted.

Further, the image forming optical system is arranged at a position close to the light receiving sensor to form an image to be read on the light receiving sensor, and the first optical unit is arranged at a position farther from the first optical unit. And a second optical unit for reducing the expansion of the visual field of the device (the invention of claim 2). According to this, it is possible to suppress the expansion of the field of view of the imaging optical system, and thus to suppress the enlargement of the light emitting region of the light guide body, so that the illumination optical system can be arranged more compactly. In this case, specifically, it is effective to employ a convex lens as the second optical unit (the invention of claim 3). Further, the imaging optical system may be a telecentric optical system in which the second optical unit focuses on the position of the first optical unit and the field of view of the first optical unit does not substantially expand ( Claim 4
According to the present invention), the apparatus can be made more compact.

By the way, the light emitting region of the light guide is generally formed in a flat plate shape for the purpose of transmitting reflected light.
Illumination light is also emitted from the surface of the light emitting region on the side of the imaging optical system to the side of the imaging optical system and thus to the light receiving sensor, which may adversely affect reading. Therefore, the ratio of the area of the light emitting area to the surface of the light emitting area on the side of the imaging optical system is 50.
The reflective portions can be provided by distributing the reflective portions so as to be less than or equal to 5% (the invention of claim 5).

According to this, by reflecting a part of the illumination light guided in the light guide body by the reflecting portion, so to speak, the leakage of the illumination light to the image forming optical system side can be reduced, and at the same time, the object to be read. The reflected light from can be transmitted from the area other than the reflecting portion and can be focused on the light receiving sensor. In this case, the light radiated from the surface of the light emitting region on the side of the imaging optical system causes the light receiving sensor to simultaneously capture the image of the surface on which the reflecting portion is formed. Since the formation position is out of the focus distance of the imaging optical system, the image is so-called defocused and the contour is unclear, and the entire image is made whitish on the light receiving sensor.
This makes it easy to identify the image to be read (information code) at the focus position.

At this time, more specifically, the reflecting portion can be formed in a mesh shape (the invention of claim 6) or can be formed in a large number of spots (claim 7).
Invention). Either of them can achieve the intended purpose of making it possible to identify the image of the information code. In this case, if the size of the mesh or the size of the spots is at least smaller than the size of the unit cell of the information code, the image to be read can be identified and is sufficiently small (for example, 1/3). By performing the following), it becomes possible to receive light with almost no loss of the shape of the information code.

Further, the light guide body may be provided with a light guide area which forms a predetermined angle with respect to the light emitting area and guides the light of the illumination light source to the light emitting area (the invention of claim 8). According to this
It is possible to prevent the entire illumination optical system including the illumination light source from being excessively large in the surface direction of the light emitting region of the light guide body, and to make the device compact. In this case, if the light guide area is formed at an angle of substantially 90 degrees with respect to the light emitting area (the invention of claim 9), the entire illumination optical system can be arranged in the most rational form. . Further, by providing a light blocking member for preventing light from the illumination light source from entering the imaging optical system (the invention of claim 10), it is possible to prevent the light receiving sensor from receiving unnecessary light.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, some embodiments of the present invention will be described with reference to the drawings.
Each of the embodiments described below applies the present invention to a handy type two-dimensional code reader. Also,
In the following embodiments, the case where a two-dimensional code (QR code) displayed on the screen of a liquid crystal display (LCD) of a PDA or a mobile phone is read as a reading target is a specific example.

(1) First Embodiment First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 schematically shows a configuration of a main part (tip part) of a handy type two-dimensional code reading device which is an optical information reading device according to the present embodiment. This two-dimensional code reading device receives an image of a reading target 2 and an illumination optical system 3 for irradiating a reading target 2 with illumination light at a tip portion of a case 1 that can be held by hand, as will be described later in detail. An image forming optical system 5 for forming an image on the sensor 4 is provided. A rectangular reading port 1a is provided at the tip (lower end) of the case 1.

Although not shown, a display unit, a key operation unit, a read instruction trigger switch, and the like are provided on the outer surface of the case 1. In addition, in this embodiment, the PDA
The screen of a liquid crystal display (LCD) of a mobile phone is set as a reading target 2, and a two-dimensional QR code C (only part of which is shown in FIG. 5A) displayed on the screen can be read. Has become. In this case, as is well known,
The liquid crystal display device has a transparent protective layer made of glass or plastic on the front surface, a liquid crystal layer on which the QR code C is actually displayed on the back surface side, and a reflective surface under the liquid crystal layer. Is configured.

The image forming optical system 5 and the illumination optical system 3 will be described in detail below. The light receiving sensor 4 is composed of, for example, a CCD area sensor, and is arranged in the case 1 so as to face downward. The image forming optical system 5 is configured by arranging a first optical section 6 which is a convex lens in this case and a second optical section 7 which is also a convex lens in front of the light receiving sensor 4 (downward in the figure). Has been done.

At this time, as shown in FIG. 1 which shows the visual field V of the imaging optical system 5 (the outer edge is indicated by a thin line), the first optical section 6 is provided.
Is arranged near the light receiving sensor 4 so as to form an image of the reading target 2 on the light receiving sensor 4, and the second optical section 7 is located at a position farther than that (the reading port 1a The first optical unit 6 is arranged (in the vicinity) so that the field of view of the first optical unit 6 is reduced. In particular, in this embodiment, the second optical unit 7 focuses on the position of the first optical unit 6 to form a telecentric optical system in which the field of view of the first optical unit 6 does not substantially expand. ing.

The illumination optical system 3 includes a plurality of LEDs 8 serving as an illumination light source, and a light guide 9 which guides illumination light from the LEDs 8 and irradiates the reading target 2 through the reading opening 1a. It is equipped with. Light guide 9
As shown in FIG. 2 to FIG. 4, is a light guide plate (light guide member) made of transparent plastic (for example, polycarbonate resin or acrylic resin) as is well known, and the left and right parts of a horizontally long rectangular plate are directed upward. It is formed in a shape (so-called channel shape) that is bent at a right angle.

Thus, the light guide 9 integrally includes a light emitting region 9a having a flat plate shape (rectangular plate shape) and light guiding regions 9b and 9b rising from the left and right side portions thereof. Composed,
The light guide area 9b is at a predetermined angle with respect to the light emitting area 9a.
It is 0 degrees. At this time, the size of the light emitting area 9a corresponds to the size of the reading port 1a, and thus covers the entire field of view of the imaging optical system 5.
As shown in FIG. 4, the corners of the left and right lower sides of the light guide 9 are in a so-called chamfered state such as being cut diagonally.

As shown in FIG. 1, the light guide 9 has the light emitting area 9a in the vicinity of the reading opening 1a (between the second optical section 7) and in parallel with the reading opening 1a. As described above, the light guide regions 9b and 9b are arranged in the case 1 and extend upward along the left and right inner wall portions in the case 1. The LED 8 as the illumination light source, as shown in FIG.
The light guide areas 9b, 9b are arranged facing downwards so as to face the upper end surfaces thereof. At this time, in the present embodiment, as shown in FIGS. 1 and 4, the LED 8 is provided on the side of the LED 8 (inside the case 1).
A plate-shaped light shielding member 10 for preventing the light from the ED 8 from entering the imaging optical system 5 is provided.

As a result, the illumination light emitted from the LED 8 is guided to the light emitting region 9a by the light guiding region 9b and is emitted downward from the light emitting region 9a. Although not shown in detail, the LED 8
Are provided side by side in the front-back direction in the figure, and the illumination light is emitted from the entire light emitting region 9a with uniform intensity (brightness).

As shown in FIGS. 2 and 3, a reflecting portion 11 is provided on the surface of the light emitting area 9a of the light guide 9 on the side of the image forming optical system 5, that is, the upper surface in the figure. In the present embodiment, the reflection portion 11 is formed in a large number of spots from, for example, black (or silver) paint, and the light emitting region 9 is formed.
They are evenly distributed over the entire light emitting region 9a so that the ratio of a to the area is 50% or less. The reflective portion 11 can be formed by a method such as printing or etching.

In the present embodiment, the unit cell of the QR code C (see FIG. 5A) has a side dimension a of, for example, 0.
Although it is a square of 25 mm to 0.5 mm, the diameter dimension b (see FIG. 3A) of one reflecting portion 11 is sufficiently small, for example, 0.05 mmφ. Thus, as will be described later in the description of the operation, a part of the illumination light guided in the light guide 9 is reflected by the reflecting portion 11, so to speak, the illumination light leaks to the imaging optical system 5 side. In addition to being able to reduce the number, the reflected light from the reading target 2 can be transmitted from the area other than the reflecting portion 11 and focused on the light receiving sensor 4.

Next, the operation of the above configuration will be described with reference to FIG. Now, when reading the QR code C displayed on the reading target 2 (for example, the screen of the liquid crystal display (LCD) of the PDA), the user sets the reading port 1a of the case 1 to the reading target 2 as shown in FIG. The trigger switch is turned on in a state where the trigger switch is brought close to and parallel to (the focus position of the imaging optical system 5). Then, LED8 is turned on,
The light is emitted by the light guide region 9b of the light guide 9 to the light emitting region 9a.
And is emitted downward as illumination light from the lower surface of the light emitting region 9a, and the illumination light is read through the reading opening 1a.
It will be irradiated to the whole.

Then, the reflected light from the QR code C displayed on the reading object 2 enters through the reading opening 1a, and the image transmitted through the light emitting area 9a of the light guide 9 is the second optical section 7 and the second image. An image is formed on the light receiving sensor 14 via the optical unit 6 of No. 1, and the QR code C can be read. At this time, the light emitting region 9a of the light guide body 9 which becomes a so-called planar light source
Therefore, it is possible to irradiate the entire reading object 2 with the illumination light, and it is possible to perform good reading even on the reading object 2 such as an LCD having a transparent protective layer on the surface.
In addition, since the light shielding member 10 is provided, the LED
It is possible to prevent light that has leaked laterally from 8 from entering the imaging optical system 5, and to prevent the light receiving sensor 4 from receiving unnecessary light.

Further, since the reflected light from the reading object 2 is transmitted through the area other than the reflecting portion 11 which occupies most of the area of the light emitting area 9a (the ratio is 50% or more), the reading object 2 (QR is not affected). The image of code C) can be formed on the light receiving sensor 4.

In this case, the image of the surface on which the reflecting portion 11 is formed overlaps with the image of the reading object 2 (QR code C) and is taken in by the light receiving sensor 4 at the same time. Since the formation position of 11 is out of the focus distance of the imaging optical system 5, a so-called defocused image with an unclear outline is formed, and the entire image on the light-receiving sensor 4 is only whitish.
It becomes easy to distinguish the image of (QR code C).

Incidentally, FIG. 5A shows an example of the QR code C (upper left portion), and FIG. 5B schematically shows an image on the light receiving sensor 4 which has transmitted through the light emitting region 9a of the QR code C. It is shown in the figure. In the present embodiment, the diameter dimension b of each reflecting portion 11 is made sufficiently smaller than the size a of the unit cell of the QR code C, so that the shape of the QR code C is not impaired on the light receiving sensor 4. The image can be displayed and the QR code C can be read.

As described above, according to this embodiment, the light to be read 2 can be irradiated with the illumination light from the light emitting region 9a of the light guide 9 which is a so-called surface light source, so that a transparent protective layer is formed on the surface. Good reading can also be performed on the read object 2 that is included.

Since the light emitting area 9a of the light guide 9 is provided within the visual field V of the imaging optical system 5,
It is possible to arrange the illumination optical system 3 more compactly than in the case where the surface light source is provided outside the field of view of the imaging optical system. Moreover, in this embodiment, the light guide area 9b is provided in the light emitting area 9.
Since it is provided so as to form an angle of 90 degrees with respect to a, LE
The entire illumination optical system 3 including D8 is prevented from becoming large in the surface direction of the light emitting region 9a of the light guide 9, and the imaging optical system 5 is provided so as to form a telecentric optical system. Therefore, the field of view V can be prevented from expanding and the light guide 9
It is possible to suppress the increase in size of the light emitting region 9a, and as a result, it is possible to suppress the increase in size of the entire device (case 1) and effectively reduce the size.

(2) Other Embodiments FIG. 6 shows a second embodiment of the present invention. The embodiment described below should be called a modification of the first embodiment. Therefore, the same parts as those of the first embodiment are designated by the same reference numerals and detailed description thereof will be omitted. Only the different points will be described below. The second embodiment differs from the first embodiment in the configuration of the image forming optical system 21, and the image forming optical system 21 includes a first stop.
The optical unit 22 and the second optical unit 7 formed of a convex lens are configured.

Also in this case, the image forming optical system 21 is provided so as to form a telecentric optical system, and therefore, the field of view V of the image forming optical system 21 can be prevented from expanding.
As a result, it is possible to prevent the light emitting region 9a of the light guide body 9 from becoming large, so that the illumination optical system 3 can be arranged compactly. As a result, as in the case of the first embodiment described above, the reading target 2 having the transparent protective layer on the surface thereof can be read well, the size increase is suppressed, and the illumination from the LED 8 is performed. The effect that light can be used effectively can be obtained.

FIG. 7 shows a third embodiment of the present invention. The difference from the first embodiment is the configuration of the image forming optical system 23. In the third embodiment, the imaging optical system 23
Has an image forming lens 24 disposed in front of the light receiving sensor 4 to form a general reduction optical system.
In this case, the field of view V of the imaging optical system 23 is expanded and the light guide 25 (light emitting area 25a) and thus the case 26 (readout opening 26a) are slightly larger than those of the first and second embodiments. However, the structure of the imaging optical system 23 is simplified, and the merit in terms of cost can be obtained.

FIG. 8 shows a fourth embodiment of the present invention. The difference between this embodiment and the first embodiment is that the reflecting portion 2 formed in the light emitting region 27a of the light guide 27 is formed.
8 is formed in a mesh shape. Also in this case, by sufficiently reducing the mesh (size of the opening) of the reflecting portion 28, it is possible to form an image on the light receiving sensor 4 with almost no loss of the shape of the information code. The same action and effect as can be obtained.

The present invention is not limited to each of the above-described embodiments. For example, the information code is not limited to a QR code, but can be applied to a device for reading various two-dimensional codes, and a bar code. It may be a type that also serves to read a one-dimensional code such as, and in the above embodiment,
Although the liquid crystal display device is the object to be read, it goes without saying that the device of the present invention can read the information code printed on the paper (label) or the like, and further, the present invention is not limited to the handy type. The invention can be appropriately modified and implemented without departing from the scope of the invention, such as being applicable to a fixed-type reader.

[Brief description of drawings]

FIG. 1 shows a first embodiment of the present invention, and is a vertical sectional front view of a main part of a two-dimensional code reading device.

FIG. 2 is a top view (a) and a front view (b) of a light guide.

FIG. 3 is an enlarged top view (a) of a part of the light guide and its x-.
Front view in vertical section along the x-ray (b)

FIG. 4 is an enlarged front view showing a light guide region portion of a light guide body.

FIG. 5 is a diagram showing an example (a) of a part of a QR code and an image (b) corresponding to the example on the light receiving sensor.

FIG. 6 is a view corresponding to FIG. 1 showing a second embodiment of the present invention.

FIG. 7 is a diagram corresponding to FIG. 1 showing a third embodiment of the present invention.

FIG. 8 is a view corresponding to FIG. 3 (a) showing a fourth embodiment of the present invention.

[Description of Reference Signs] In the drawings, reference numerals 1 and 26 denote cases, 1a and 26a denote reading ports, and 2
Is an object to be read, 3 is an illumination optical system, 4 is a light receiving sensor, and 5, 2
Reference numerals 1 and 23 are image forming optical systems, 6 is a first optical unit (convex lens), 7 is a second optical unit (convex lens), 8 is an LED (illumination light source), 9, 25 and 27 are light guides, and 9a. , 25a, 2
7a is a light emitting area, 9b is a light guiding area, 10 is a light blocking member, 1
Reference numeral 1 is a reflecting portion, 22 is a first optical portion (aperture), and 28 is a reflecting portion.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hisashi Shigusa             4-12 Toranomon, Minato-ku, Tokyo Toranomon             4-chome Mori Building No.2 Denso Co., Ltd.             In the wave F-term (reference) 5B072 CC21 CC24 DD02 GG07 LL01                       LL07 LL11 LL18

Claims (10)

[Claims] 1. An optical information reading apparatus comprising: an illumination optical system for irradiating a reading object having an information code written thereon with illumination light; and an imaging optical system for forming an image of the reading object on a light receiving sensor. And the illumination optical system has an illumination light source and a light emitting region covering the entire field of view of the imaging optical system, which is located closer to the reading target than the imaging optical system, and is illuminated from the illumination light source. A light guide body that guides light to irradiate the light from the light emitting area toward the reading object, and the imaging optical system is configured to display an image of the reading object that has passed through the light emitting area of the light guiding body on the light receiving sensor. An optical information reading device characterized in that it is configured to form an image on. 2. The image forming optical system includes a first optical unit arranged at a position close to the light receiving sensor to form an image of the reading target on the light receiving sensor, and a first optical unit arranged at a position farther from the first optical unit. The second optical unit for reducing the expansion of the field of view of the first optical unit is provided.
The optical information reading device described. 3. The optical information reading device according to claim 2, wherein the second optical unit includes a convex lens. 4. The second optical unit forms a telecentric optical system which focuses on the position of the first optical unit and does not substantially widen the field of view of the first optical unit. The optical information reader according to claim 2 or 3. 5. The light emitting region of the light guide has a flat plate shape,
5. A reflecting portion is provided on the surface of the light emitting region on the side of the imaging optical system, and the reflecting portion is distributed so that the ratio to the area of the light emitting region is 50% or less. An optical information reading device described in (1). 6. The optical information reading device according to claim 5, wherein the reflecting portion is formed in a mesh shape. 7. The optical information reading device according to claim 5, wherein the reflecting portion is formed in a large number of spots. 8. The light guide body is configured to have a light guide area that forms a predetermined angle with respect to the light emitting area and guides the light of the illumination light source to the light emitting area. 1
8. The optical information reader according to any one of items 1 to 7. 9. The optical information reading device according to claim 8, wherein the light guide region makes an angle of substantially 90 degrees with the light emitting region. 10. The optical information reader according to claim 1, further comprising a light blocking member that prevents light from the illumination light source from entering the imaging optical system.