JP2002269490A - Information code reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that a conventional information code reading device is not practical because the scope of reading angle (pitch skew angle) becomes too narrow to photograph regular reflection light. SOLUTION: A beam splitter 14 is arranged between an information code X and a photographing lens 7 on the optical axis P, an illumination body 13 is arranged on its reflection optical axis Q, and a reading window 12 is positioned on the focus face of a photographing system to irradiate the information code X with illumination light through the beam splitter 14 and to image focus reflection light on a photographing element 6 with the photographing lens 7 so as to enable reading of the information codes reflecting regularly irrespective of a compact shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an information code reader for reading information codes such as bar codes and two-dimensional codes.

[0002]

2. Description of the Related Art As a conventional information code reader, there is a hand-held code reader. This hand-held code reader includes a reader body 31 having a grip portion 30 as shown in FIGS. 6 to 8.
A reading section 32 is provided at the end of the reading section 32. The reading section 32 is provided with an opening 33 and an LED lighting section 34 disposed around the opening 33. Further, a trigger button 35 is provided on the grip portion 30, and an operation indicator light 37 is provided on the reader body 31. Further, an imaging lens 3 for imaging shown in FIG.
9 and an image sensor 38 are arranged.

[0003] An operator holds the code reader by grasping the grip section 30 and holds the reading section 32 with the information code 3.
6, by pressing the trigger button 35, the illumination code of the illumination unit 34 is irradiated on the information code 36, and the reflected light from the information code 36 is received by the image sensor 38. Image processing is performed using the reflected light from the information code 36 received at 38 as image information, and the information code 36 is recognized by this image processing.

[0004]

However, in the above-mentioned conventional hand-held code reader, the information code 36 facing the imaging lens 39 is printed on the polished surface (mirror surface) as shown in FIG. If so, the reflected light becomes specularly reflected light and does not enter the image sensor 38.

In particular, when reading an information code 36 formed by peeling a metal film deposited on a glass surface with a laser marker or the like, the use of illumination as shown in FIG. 9 is affected by the background state of the glass. Reading is difficult.

Further, in an information code 36 or the like drawn by a laser marker on a metal rough surface, a specular reflection light is obtained from a code portion, and only a reflection light having a random intensity distribution is obtained from a background. Hard to get.

That is, when the information code 36 is not printed on paper, but is read, for example, when the information code 36 is marked using a laser marker or the like on a polished metal or a metal-deposited surface of a glass surface, an illumination is required. Are random and the reflected light is almost specularly reflected light, the amount of reflected light incident on the imaging lens 39 is reduced, and a good image cannot be obtained.

If light other than the illumination light from the code reader enters the information code 36 and the reflected light enters the image sensor 38, the information code 36 cannot be read.

Further, a small information code 36
In order to take advantage of the characteristics of the two-dimensional code that can be configured, when the size of the cell that configures the information code 36 is reduced, the imaging area of the code reader can be adjusted to the information code 36,
It is very difficult to match the information code 36 to the focal position.

[0010] In particular, the conventional hand-held code reader has a problem that the range of the reading angle (pitch skew angle) is extremely narrow for capturing specularly reflected light, which is not practical.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to solve the above-mentioned conventional problems. An object of the present invention is to provide an information reading device capable of reading a code.

[0012]

In order to achieve the above object, an information code reading apparatus according to the present invention irradiates an information code with light, and receives reflected light from the information code by an image pickup device. In an information code reader that performs image processing using reflected light from an information code received by the image sensor as image information and recognizes the information code by the image processing, one or more light emitting elements and one or more light emitting elements A diffusing plate disposed in front of a light emitting surface of the element and diffusing light emitted from one or more light emitting elements; irradiating the information code with light by bending an optical axis of the light diffused by the diffusing plate; A partially transmissive flat reflective surface that transmits the reflected light from the code,
An imaging lens for forming an image of the light transmitted through the plane reflecting surface on the imaging device.

The one or more light emitting elements are a large number of L
A beam splitter, a half mirror, and the like, which include an aggregate of EDs and a surface-emitting LED, and have a partially transmissive plane reflecting surface that bends the optical axis of light are included.

With this configuration, the light emitted from the one or more light emitting elements is diffused by the diffusion plate, and the optical axis of the diffused light is bent by the plane reflecting surface to irradiate the information code. An information code reader can be configured using a coaxial optical system using a partially transmissive plane reflecting surface so that the reflected light is transmitted through the plane reflecting surface and imaged on the image sensor by the imaging lens. Therefore, it is possible to read an information code which has a small shape and which is regularly reflected.

The information code reader according to the present invention is the information code reader according to the present invention described above, wherein the component emitted in the direction perpendicular to the optical axis of the light emitted from the diffuser of the reflecting surface of the flat reflecting surface. Is larger than the size of the emission light source on the diffusion plate for the light emitted from the diffusion plate.

The size of an emission light source on the diffusion plate for light emitted from the diffusion plate means that when light emitted from one or more light emitting elements (for example, surface emission) is diffused by the diffusion plate, This is the dimension of an effective portion that diffuses light in the diffusion plate and emits the light to the reflecting surface of the flat reflecting surface. When the emission light source is a circle, for example, the effective portion is a square inscribed in the circle, and the dimension of the effective portion corresponds to the length of one side of the square. Further, the dimension of the plane reflecting surface is a dimension of an effective portion which reflects light emitted by being diffused by the diffusion plate. In the case of the beam splitter, the length dimension of each side is a plane including two diagonals equally. It corresponds to the length of one side of a certain square.

With this configuration, the size of the component of the light emitted from the diffusion plate on the surface reflecting surface in the direction perpendicular to the optical axis is determined by the size of the emission light source on the diffusion plate for the light emitted from the diffusion plate. By making it larger, the pitch skew angle range in which specularly reflected light of the information code marked on the polished metal surface can be obtained is widened, and this information code (two-dimensional code) can be read.

In the information code reader according to the present invention, in the above information code reader according to the present invention, the size of the opening in the information code surface of the apparatus body is W,
When the optical distance from the information code to the diffusion plate is L and θ is a pitch skew angle which is a desired reading angle, the size of the emission light source is a value larger than (2 × L × tan2θ + W) and θ is 0 ° to less than 45 °.

With this configuration, the size of the emission light source is (2
× L × tan2θ + W) and θ is 0
If the range is less than 45 ° to 45 °, the light emitted from the emission light source is applied to the information code, and the reflected light from the information code returns to the image sensor, and is marked on the polished metal surface. The information code can be read.

In the information code reader according to the present invention, in the information code reader according to the present invention, the size of the emission light source on the diffusion plate for the light emitted from the diffusion plate is set to (2 × L × tan6). ° + W).

With this configuration, even when the pitch skew angle is inclined by 3 ° or more, the light emitted from the emission light source is irradiated on the information code, and the reflected light from the information code returns to the image pickup device, and the polishing is performed. The information code marked on the marked metal surface can be read.

In the information code reader according to the present invention, in the information code reader according to the present invention, the size of the light source on the diffusion plate for the light emitted from the diffusion plate is set to (2 × L × tan70). ° 10 W).

With this configuration, if the pitch skew angle is within 35 degrees, the light emitted from the emission light source is applied to the information code, and the reflected light from the information code returns to the image pickup device, and is polished. It is possible to read the information code marked on the metal surface.

Further, even if the pitch skew angle is 35 degrees or more, the light emitted from the emission light source is applied to the information code, and the reflected light from the information code returns to the image sensor. A large-sized partially transmissive flat reflective surface and a large-sized light-emitting surface are required, resulting in a large-sized information code reader, which is not suitable for hand-held use.
As described above, the size of the emission light source is set to (2 × L × tan70
If it is smaller than (10 W), an information code reader which is small and suitable for a hand-held type can be provided.

In the information code reader according to the present invention, in the above information code reader according to the present invention, the size of the opening in the information code surface of the apparatus body is W,
When the width of the surface involved in imaging of the image sensor is S, the optical distance from the information code surface to the imaging lens is L1, and the focal length of the imaging lens is f, S (L1 / f-1) is the information code surface. Is equal to or smaller than the dimension W of the opening.

It is to be noted that W = S (L1 / f-1) is equal to S / W =
This is an equation in which L0 is eliminated from L0 / L1 and l / f = 1 / L0 + 1 / L1. Here, L0: when the optical distance from the imaging lens to the imaging surface satisfies W = S (L1 / f-1), that is, S
When / W = L0 / L1 and 1 / f = 1 / L0 + I / L1 are satisfied, the area of the opening (dimension W) is imaged on the width S of the surface of the imaging element involved in imaging. Therefore, S (L1 /
If f-1) is made equal to the size W of the opening on the information code surface, the area of the opening is substantially imaged on the width S of the surface involved in the imaging of the image sensor, and disturbance light not involved in reading the information code is generated. Also, the light does not enter the width S of the surface of the imaging element involved in imaging. When S (L1 / f-1) is set to S, L1, f which is smaller than the size W of the opening on the information code surface, the area of the opening becomes smaller than the size W of the opening on the information code surface. In addition, the area of the opening is limited, so that disturbance light that is not involved in reading the information code can be further limited, and the pitch skew angle of the information code surface can be largely allowed. Note that the size W of the opening can be limited by a shielding member or the like.

The information code reader according to the present invention has a hand-held structure in which the main body of the information code reader according to the present invention has a grip portion.

With this configuration, an information reading device capable of reading an information code (two-dimensional code) marked on a polished metal surface of an object can be used as a hand-held type.

[0029]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view of an information code reading apparatus according to the present invention, FIG. 2 is a partially sectional front view of the information code reading apparatus, and FIG. 3 is an explanatory view of an optical system in the information code reading apparatus. FIG. 4 is an explanatory diagram of a reading angle (pitch skew angle).

The information code reader according to the present invention is of a hand-held type. This information code reader has a hollow grip portion 1A that can be gripped and held by a worker's hand.
And a holder 10 which is a light shielding member attached to the front end of the device main body 1.

The front end of the apparatus main body 1 is a solid mounting portion 2, which is inclined at a predetermined angle with respect to the grip portion 1. The mounting portion 2 is provided with a mounting hole 3 at a position deviated from the center thereof.
An element mounting section 4 is formed on the inner end side, and an imaging lens mounting section 5 is formed on the outer end side. An imaging element 6 such as an area CCD is mounted on the element mounting section 4. An imaging lens 7 is mounted on the mounting section 5. The imaging device 6 and the imaging lens 7 constitute an imaging system.

The holder 10 has an illumination body mounting portion 8 inside.
And a beam splitter mounting section 9 are provided.
A reading window forming portion 11 having a funnel shape is provided on an end surface portion 10a of the holder 10 which is an information code surface, and a reading window 12 which is a rectangular opening as a view restriction means is provided on an end surface of the reading window forming portion 11. It is formed.

An illuminating body 13 serving as an illuminating means is provided in the illuminating body mounting section 8, and a cube-type beam splitter (a beam which is bent by bending the optical axis of the light diffused by the diffusion plate 13 A) is provided in the beam splitter mounting section 9. A partially transmissive plane reflecting surface that irradiates the information code X and transmits the reflected light from the information code X)
1 to 3, a beam splitter 14 is disposed on the optical axis P between the information code X and the imaging lens 7, and the reflected optical axis Q The illumination body 13 is arranged. Further, a reading window 12 is located on a focus surface of the imaging system.

The illuminating body 13 uses one or more light emitting elements. In other words, the illuminating body 13 is a uniform surface emitting illumination, the luminous surface is as large as possible, and the luminous characteristics are such that a constant intensity is obtained in any direction, or a luminous body exhibiting characteristics close to Lambert's law, Surface-emitting LED
Is used.

A diffusion plate 13A for diffusing the light emitted from the illuminating body 13 is disposed in front of the light emitting surface of the illuminating body 13. In this case, an emission light source of light emitted from the diffusion plate 13A is formed on the diffusion plate 13A.

The size of the illuminator 13 (the length of one side in the case of a square) is A (mm), the distance from the diffusion plate 13A to the beam splitter 14 is t (mm), and the length of one side of the beam splitter 14 is Length B (mm), Beam splitter 1
L2 is the distance from the focusing surface of the imaging lens 7 to L2.
(Mm), the size of the reading window 12, that is, the size of the opening (field of view) (the length of one side when a square) is W
(Mm), as shown in FIGS. 3 and 4, tan θi = (A−W) / 2 / (L20B + t) θi = arctan ｛(A−W) / 2 / (L20B +
t)｝ is the maximum value of the angle at which the illumination light enters the information code X. Actually, since the beam splitter 14 is usually made of glass, an angle slightly larger than the above-mentioned angle θi becomes the maximum value in consideration of the refractive index, but is expressed by the above equation for simplicity.

Light reflected from a diffuse reflection surface such as paper emits reflected light in any direction regardless of the direction of the incident light from the illuminating body 13. Since most of the reflected light is emitted in a direction uniquely determined, the angle range of the incident light defines the pitch skew angle θ.

As shown in FIG. 4, the relationship between the incident angle θi of the illumination light F to the information code X and the angle (pitch / skew angle) θ of the information code X with respect to the image pickup system is as follows: θ = θi /
It becomes 2.

The light exits from the diffusion plate 13A rather than the length B of one side of the square surface facing the diffusion plate 13A in the beam splitter (the size obtained by multiplying the size of the reflection surface of the plane reflection surface by sin 45 °). The size of the emission light source on the light diffusion plate 13A is increased.

In this case, the size of the light emitted from the diffuser 13A on the diffuser 13A means that the light emitted from the illuminating body 13 is diffused by the diffuser 13A. Is the size of the effective portion that diffuses and emits. When the emission light source is a circle, for example,
The effective portion is a square inscribed in a circle, and the dimension of the effective portion corresponds to the length of one side of the square.

As described above, the diffusion plate 1 of the light emitted from the diffusion plate 13A is larger than the length B of one side of the square surface facing the diffusion plate 13A in the beam splitter 14.
By increasing the size of the emission light source on the 3A, the range of the pitch skew angle θ at which the specular reflection of the information code X marked on the polished metal surface can be widened, and this information code (two-dimensional code ) X can be read.

Then, the size of the reading window 12, which is an opening on the information code surface of the apparatus main body 1, is W, and the optical distance from the information code X to the diffusion plate 13A is L = (L20 + B + t).
When θ is a pitch skew angle that is a desired reading angle, the size of the emission light source is (2 × L × tan 2θ).
+ W) and θ ranges from 0 ° to less than 45 °.

As described above, the size of the emission light source is (2 × L ×
tan2θ + W), and if the pitch skew angle θ is in the range of 0 ° to less than 45 °, the light emitted from the emission light source is applied to the information code X, and the reflected light from the information code X is It returns to the image sensor 6,
It becomes possible to read the information code X marked on the polished metal surface.

The size of the light emitted from the diffusion plate 13A on the diffusion plate 13A is set to (2 × L × ta).
n6 ° + W), the light emitted from the emission light source is applied to the information code X even if the pitch skew angle θ is inclined by 3 ° or more, and the reflected light from the information code X is used as an image sensor. Then, the information code X marked on the polished metal surface can be read.

The size of the light emitted from the diffusion plate 13A on the diffusion plate 13A is set to (2 × L × ta).
If the pitch skew angle θ is less than 35 degrees, the light emitted from the emission light source is irradiated on the information code X, and the reflected light from the information code X is reflected on the image sensor 6. And the information code X marked on the polished metal surface can be read.

Further, even when the pitch skew angle θ is 35 degrees or more, the light emitted from the emission light source is applied to the information code X, and the reflected light from the information code X returns to the image sensor 6. In order for the beam splitter 14
A large-sized partially transmissive plane reflecting surface, a large-sized illuminating body (light-emitting surface) 13 and a diffusion plate 13A are required, so that the information code reader has a large shape and is not suitable for a hand-held type. The size of the emission light source is (2
× L × tan 70 ° tens W), it is possible to provide a small-sized information code reader suitable for a hand-held type.

Further, the dimension of the reading window 12 which is an opening on the information code surface of the apparatus main body 1 is W, the width of the surface of the image pickup device 6 involved in imaging is S, and
S (L1 / f-1) is equal to or smaller than the dimension W of the opening in the information code plane, where L1 is the optical distance to the optical lens and f is the focal length of the imaging lens 7.

In this case, W = S (L1 / f-1) is equal to S /
W = L0 / L1 and l / f = 1 / L0 + 1 / L1 to L0
Is an equation in which is deleted. Here, L0: when the optical distance from the imaging lens to the imaging surface satisfies W = S (L1 / f-1), that is, S
When / W = L0 / L1 and 1 / f = 1 / L0 + I / Ll, the area of the opening (dimension W) is imaged on the width S of the surface of the image sensor 6 involved in imaging. Therefore, S (L1
If / f-1) is made equal to the dimension W of the opening on the information code surface, the area of the opening is substantially imaged on the width S of the surface involved in the imaging of the image sensor, and disturbance light not involved in reading the information code. However, the light does not enter the width S of the surface of the imaging element involved in imaging. When S (L1 / f-1) is set to S, L1, f which is smaller than the size W of the opening on the information code surface, the area of the opening becomes smaller than the size W of the opening on the information code surface. In addition, the area of the opening is limited, so that disturbance light that is not involved in reading the information code can be further limited, and the pitch skew angle of the information code surface can be largely allowed.
Note that the size W of the opening can be limited by a shielding member or the like.

A trigger switch 15 is provided on the front of the apparatus body 1, and a cable 17 is attached to the rear end of the grip 1A via a cable connection section 16. Is an image sensor control board 6a
Are connected to the lead wire 18 led out from the output side.
The trigger switch 15 supplies electric power to the image sensor 6 and the illuminating body 13 when turned on.

Next, a method of using the information code reader (code reader) configured as described above will be described.

The operator grips the grip section 1A, holds the information code reader (code reader) in his hand, brings the reading window 12 close to the edge of the information code X, and turns on the trigger switch 15 in this state. It operates to supply electric power to the image sensor 6 and the lighting body 13.

When the power is supplied, the illuminating body 13 emits the illuminating light A as the diffused light as shown in FIG. The illumination light a enters the beam splitter 14 and is refracted from the reflection optical axis Q side to the optical axis P side to irradiate the information code X from the reading window 12 which is an opening. In this case, the illumination light A becomes the incident light flux B by the reading window 12.

The reflected light (specularly reflected light) reflected by the information code X passes through the beam splitter 14 and enters the imaging lens 7, which forms the information code X on the energy conversion surface of the imaging element 6. Let it. This formed input image is converted into a current distribution according to the input distribution,
This signal is input to the control unit 19 via the lead wire 18 and the cable 17. In the control unit 19, after the signal is A / D converted as shown in FIG.
The data is subjected to value processing, then decoded, and output as data.

As described above, according to the embodiment of the present invention, it is possible to read an information code which is small in size and which is specularly reflected, and allows only the specularly reflected light to enter the image sensor 6. It is possible to read a two-dimensional code which cannot be read by a conventional hand-held code reader.

Further, the size of the emission light source on the diffusion plate 13A for the light emitted from the diffusion plate 13A is made larger than the length B of one side of the square surface facing the diffusion plate 13A in the beam splitter 14. Thus, the range of the pitch skew angle θ at which the specular reflection light of the information code X marked on the polished metal surface is obtained is widened, and the information code (two-dimensional code) X can be read.

Further, even if the reading window 12 does not exactly match the field of view, the size S (mm) of the image sensor 6 and the focal length f of the image sensor 7, and the distance from the image sensor 6 to the image sensor 7 can be obtained. If the field of view is limited by the field of view determined by L0, assembling adjustment becomes easier if the reading window 12 is made larger than the field of view.

In order to obtain specularly reflected light, the beam splitter 14 desirably has a polarization characteristic of 1: 1 for both S-polarized light and P-polarized light at the wavelength of the illumination light and has as wide an angle characteristic as possible.

If transmission and reflection are reversed and the image pickup system is bent by 90 ° by the beam splitter 14, even if a half mirror in which a multilayer film is deposited on a plate glass instead of a cube type is used, the image pickup surface can be changed. There is no problem because no astigmatism occurs.

[0060]

As described above, according to the information code reading apparatus of the present invention, light emitted from one or more light emitting elements is diffused by the diffusion plate, and the optical axis of the diffused light is adjusted. A partially reflective flat reflective surface was used so that the information code was irradiated by bending it with the flat reflective surface, and the reflected light from this information code was transmitted through the flat reflective surface and imaged on the image sensor by the imaging lens. Since the information code reader can be configured using the coaxial optical system, it is possible to read an information code that is regularly reflected while having a small shape.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an information code reading device according to the present invention.

FIG. 2 is a partially sectional front view of the information code reader.

FIG. 3 is an explanatory diagram of a configuration of an optical system in the information code reading device.

FIG. 4 is an explanatory diagram of a reading angle (pitch skew angle).

FIG. 5 is an operation block diagram of the information code reader.

FIG. 6 is a side view of a conventional information code reader.

FIG. 7 is a plan view of the information code reader.

FIG. 8 is a front view of the information code reader.

FIG. 9 is an explanatory diagram of a configuration of an optical system in the information code reading device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Device main body 1A Grip part 2 Mounting part 3 Mounting hole part 4 Element mounting part 5 Imaging lens mounting part 6 Imaging element 7 Imaging lens 8 Illumination body mounting part 9 Beam splitter mounting part 10 Holder (light shielding member) 10a End face (information code Surface) 11 reading window forming unit 12 reading window (opening) (view restriction means) 13 illuminating body (illuminating means) 14 beam splitter (optical element) 15 trigger switch 16 cable holder 17 cable 18 lead wire 19 control unit

Claims (7)

[Claims] An image code is irradiated with light, reflected light from the information code is received by an image sensor, and image processing is performed using the reflected light from the information code received by the image sensor as image information. An information code reader for recognizing the information code by this image processing, wherein at least one light emitting element is disposed in front of a light emitting surface of the one or more light emitting elements and emitted from the one or more light emitting elements. A diffuser for diffusing the light to be transmitted; and a partially transmissive member for bending the optical axis of the light diffused by the diffuser plate, irradiating the information code with the light, and transmitting the reflected light from the information code. An information code reading device, comprising: a flat reflecting surface; and an imaging lens that forms an image of light transmitted through the flat reflecting surface on the imaging device. 2. A light source for emitting light emitted from the diffusion plate on the diffusion plate, wherein a dimension of a component of the light emitted from the diffusion plate on the reflection surface of the plane reflection surface is perpendicular to an optical axis. 2. The information code reader according to claim 1, wherein the information code reader is larger than the size of the information code. 3. When the size of the opening on the information code surface of the apparatus body is W, the optical distance from the information code to the diffusion plate is L, and θ is a pitch skew angle which is a desired reading angle. 3. The information code reader according to claim 1, wherein the size of the emission light source is a value larger than (2 × L × tan2θ + W) and θ is in a range of 0 ° to less than 45 °. 4. The size of the emission light source on the diffusion plate for light emitted from the diffusion plate is (2 × L × tan6).
The information code reader according to any one of claims 1 to 3, wherein the information code reader is larger than (° + W). 5. The size of the emission light source on the diffusion plate for light emitted from the diffusion plate is (2 × L × tan7).
The information code reader according to claim 3 or 4, wherein the information code reader is smaller than 0 ° and 10 W). 6. The size of the opening on the information code surface of the apparatus main body is W, the width of a surface involved in imaging of the image sensor is S, and the optical distance from the information code surface to the imaging lens is L1. 6. An image pickup lens according to claim 3, wherein S (L1 / f-1) is equal to or smaller than a size W of an opening in the information code surface, where f is a focal length of the imaging lens. Information code reader. 7. The information code reading device according to claim 1, wherein the device main body is a hand-held type having a grip portion.