JP4501801B2 - Optical information reader - Google Patents

Description

  The present invention relates to an optical information reading apparatus including an illumination light source and an illumination lens, and including an illumination optical system that irradiates illumination light toward a reading target on which an information code is written.

  For example, a handy type barcode reader that reads a barcode (one-dimensional code) as an information code illuminates a reading object (a label on which a barcode is printed) with illumination light that is horizontally long in a main body case having a reading opening. And an optical receiving system that receives (images) reflected light from a reading target from a light receiving sensor such as a CCD sensor via an imaging lens. The illumination optical system is configured by arranging a so-called kamaboko-shaped illumination lens made of a plastic molded product in front of a plurality of LEDs serving as illumination light sources. In this case, the illumination lens condenses the light from the LED in the vertical direction and diffuses it so as to have an appropriate illuminance distribution in the horizontal direction so that bright light can be obtained near or far from the reading port. The function to be made is required.

Specifically, in Patent Document 1, as an illumination lens used in an illumination optical system of a barcode reader, the incident surface side is a lenticular lens in which a large number of fine irregularities extending vertically are formed, and the exit surface side is a cylinder. A cylinder lens having a surface is disclosed. Moreover, in this patent document 1, LED with a narrow directivity angle (for example, 30 degrees or less) is employ | adopted as an illumination light source. Furthermore, as another example, Patent Document 2 discloses, as an illumination lens, a first lens that collects light emitted from an LED to make the light uniform in the horizontal direction, and condenses the light in the vertical direction. A lens having two lenses, a second lens having a horizontally long belt shape, is disclosed.
JP 2004-266621 A Japanese Patent No. 2690125

  However, the above prior art has the following points to be improved. That is, in the illumination lens described in Patent Document 1, since a lenticular lens having a fine shape is adopted, fine mold processing is required for molding, and the life of the mold is also relatively short. The cost was high. In addition, there has been a situation where a special LED with a narrow directivity angle has to be adopted as an illumination light source.

  On the other hand, in the illumination lens described in Patent Document 2, since two lenses are used, the number of parts is large and the number of assembling steps is increased, which increases the cost and may increase the size of the entire apparatus. was there. Furthermore, even if an attempt is made to increase the number of LEDs serving as light sources in order to obtain high-intensity illumination light, the light from the LEDs arranged at a position close to the first lens is collected, but arranged apart from each other. There is a problem that the light from the LED is not condensed and the illumination efficiency of the illumination light is reduced.

  The present invention has been made in view of the above circumstances, and an object thereof is to include an illumination optical system that irradiates illumination light toward a reading target, and can irradiate illumination light efficiently with high luminance. However, it is an object of the present invention to provide an optical information reading apparatus capable of simplifying the construction of the illumination optical system at a low cost.

In order to achieve the above object, an optical information reading apparatus according to the present invention includes an illumination light source and an illumination lens, and includes an illumination optical system that irradiates illumination light toward a reading target. The light source is configured to include two or more LEDs, and the illumination lens has a lens shape on the incident surface side that condenses the light emitted from the LEDs facing each of the LEDs, The present invention is characterized in that the exit surface is provided with a lens shape that condenses incident light in a direction perpendicular to the reading width direction of the information code (invention of claim 1).

  According to this configuration, in the illumination optical system, the light emitted from the plurality of LEDs is incident on the incident surface side of the illumination lens and is condensed, and then the information code is transmitted by the exit surface of the illumination lens. The light is condensed in a direction perpendicular to the reading width direction and emitted as illumination light that is horizontally long in the reading width direction. At this time, the incident surface of the illumination lens has a function of condensing the light from the LED instead of diffusing it, so there is no need for a fine shape like a lenticular lens, and a relatively simple lens shape. You can do it. In addition, a single illumination lens can be used. Furthermore, since the lens shape for condensing is provided corresponding to each LED on the incident surface side of the illumination lens, the light from the plurality of LEDs can be efficiently used as illumination light. Moreover, it is possible to employ a high-luminance LED having a wide directivity angle (for example, 90 ° or more) without requiring a special LED having a narrow directivity angle as an illumination light source.

  Accordingly, it is possible to obtain bright illumination light having a uniform illuminance distribution in the reading width direction and near or far from the reading port. As a result, according to the first aspect of the present invention, there is provided an illumination optical system that irradiates illumination light toward a reading target, and illumination light can be efficiently emitted with high luminance. It is possible to obtain an excellent effect that the configuration of the system is simple and inexpensive.

In this case, more specifically, the incident side of the illumination lens, wherein in each opposed to each LED, may be configured to, be convex LED side spherical or aspherical curved (according Item 2). Thereby, the light emitted from each LED can be condensed by the curved convex on the incident surface side, and efficient illumination light can be generated. In addition, the illumination lens does not require a fine shape, and the life of the mold can be extended. Note that a cylindrical surface lens (cylinder lens) similar to the conventional one can be employed for the exit surface side of the illumination lens.

  Further, each LED can be arranged at the focal position of the illumination lens (invention of claim 3), and thereby illumination light composed of parallel light can be emitted. Or it is good also as a structure which arrange | positions each said LED between the said lens for illumination, and the focus position of this lens for illumination (invention of Claim 4), and, thereby, illumination light which spreads so that it goes ahead Can be obtained.

  Hereinafter, an embodiment in which the present invention is applied to a handy type bar code reader (bar code handy terminal) that reads a bar code (one-dimensional code) will be described with reference to the drawings. As shown in FIG. 4, the barcode reader 1 as an optical information reader according to the present embodiment has a vertically long shape in a main body case 2 having a size that can be operated by a user with one hand. Further, a reading mechanism 3 (see FIG. 3) for reading a barcode B as an information code recorded on a reading object R such as a label is arranged.

  As shown in FIG. 3, the reading mechanism 3 receives an illumination optical system 4 as an illuminating unit that irradiates a long strip-shaped illumination light L toward the reading target R, and receives reflected light from the reading target R (imaging). The light receiving optical system 5 as a light receiving means for reading the bar code B, and a marker optical system that irradiates the reading light R with marker light indicating the reading position, although not shown, are configured. The illumination optical system 4 and the light receiving optical system 5 will be described later.

  As shown in FIG. 4, the front end surface of the main body case 2 is provided with a reading port 2a having a horizontally long rectangular shape and translucency. A display unit 6 and a key operation unit 7 are provided on the upper surface of the main body case 2, and a trigger key 8 for reading instructions is provided on the left and right side surfaces of the main body case 2. Further, although not shown in the figure, the main body case 2 includes a control circuit for performing overall control and decoding processing of the read barcode B, a communication circuit for performing communication with the outside, and a driving power source. A secondary battery or the like is provided.

  As shown in FIG. 3, the light receiving optical system 5 includes a light receiving sensor 9 including a CCD area sensor (or a CCD line sensor) disposed on the front end side in the body case 2, and a front side of the light receiving sensor 9. The imaging lens 10 is arranged. Although not shown in detail, the imaging lens 10 is configured by arranging a plurality of lenses in a lens barrel, for example. The reading optical axis O of the light receiving optical system 5 extends in a state (horizontal state) where the center of the reading port 2a is orthogonal to the surface of the reading port 2a. The light receiving optical system 5 has a horizontally long reading field.

  Now, the illumination optical system 4 will be described with reference to FIGS. As shown in FIG. 1, the illumination optical system 4 includes two or more (plural) LEDs 11 serving as illumination light sources, and is positioned in front of the LEDs 11 and collects light from the LEDs 11 to form a horizontally long strip-shaped illumination. A single illumination lens 12 for the light L is provided. At this time, as shown in FIG. 1, the illumination optical system 4 is positioned on the left and right sides of the imaging lens 9, and two sets are provided symmetrically with respect to the reading optical axis O. . In this case, the LED 11 is a general-purpose LED having a wide directivity angle (90 ° or more, for example, 110 °) and high brightness, and three LEDs 11 are provided side by side.

  The illumination lens 12 is configured as follows. That is, as shown in FIG. 2, the illumination lens 12 is made of a transparent plastic molded product, and has a horizontally long shape corresponding to the LED 11 in which the three are arranged. The illumination lens 12 has a lens shape for condensing light emitted from the LEDs 11 corresponding to each LED 11 on the incident surface side (side facing the LED 11), and on the emission surface side (front surface side). The lens is configured to collect incident light in a direction (longitudinal direction) perpendicular to the reading width direction of bar code B (bar arrangement direction).

  Specifically, as shown in FIG. 2, the illumination lens 12 includes a base portion 12a having a horizontally long rectangular thin plate shape, a cylinder lens portion 13 positioned on the front surface side thereof, and a rear surface side of the base portion 12a. In this case, three spherical lens portions 14 are integrally formed. The cylinder lens portion 13 extends substantially in the horizontal direction on the front surface of the base portion 12a, and is configured in a cylindrical surface shape (so-called kamaboko type) with the axial direction as the horizontal direction. The spherical lens portion 14 is configured in a spherical shape (dome shape) that is convex rearward (to the LED 11 side), and three are provided side by side so as to correspond (oppose) to the three LEDs 11, respectively. Yes.

In the present embodiment, each LED 11 is arranged at a focal position behind the illumination lens 12. At this time, as illustrated for the so-called kamaboko type lens A in FIG. 5, in the general formula of geometric optics, the focal length of the lens A is f, the lens curvature of the exit surface is r1, the lens curvature of the entrance surface is r2, and the lens If the refractive index of A is N,
(1 / f) = (N−1) {(1 / r1) − (1 / r2)}
There is a relationship. It is known that if the light source p is arranged at the position of the focal length f, the light emitted from the exit surface of the lens A becomes parallel light that does not spread in the vertical direction.

  With the illumination optical system 4 configured as described above, the light emitted from the LED 11 is collected by the illumination lens 12 and spreads in the lateral direction (reading width direction), as will be described in detail in the following description of the operation. In the vertical direction, it is emitted as a thin strip-like illumination light L from the reading port 2a toward the front (left side in FIG. 3). Accordingly, the illumination light L that is long in the reading width direction is irradiated to the reading object R. At this time, the illumination optical axis of the illumination light L emitted from the left and right illumination optical systems 4 (illumination lenses 12) is in the same optical plane as the optical plane including the reading optical axis O of the light receiving optical system 5. It is located in (horizontal plane). The illumination light L is lit when reading the barcode B (when capturing an image).

  Next, the operation of the above configuration will be described. When reading the barcode B by the barcode reader 1, the user keeps the main body case 2 away from the reading target R by an appropriate distance, and the reading port 2a is read from the reading target in which the horizontal barcode B is recorded. Orient to be almost parallel to R. In this case, the user can perform alignment between the reading port 2a and the reading target R by irradiating the reading target R with marker light (not shown).

  When the trigger key 8 is turned on in this state, as shown in FIG. 4, the marker light is turned off, the LED 11 is turned on, and the illumination optical system 4 causes the barcode B portion to pass through the reading port 2a. Is irradiated with a horizontally long strip-shaped illumination light L. Then, the reflected light from the barcode B enters through the reading port 2a and forms an image on the light receiving sensor 9 through the imaging lens 10, whereby the barcode B is read. At this time, the illumination optical axis and the reading optical axis O are arranged in the same optical plane (in the horizontal plane), so that good reading is performed.

  Here, in the illumination optical system 4 described above, light emitted forward from each LED 11 enters the illumination lens 12 as light having a wide directivity angle and diffusing in a circular shape. . Then, the incident light is condensed by the spherical lens portion 14 on the incident surface side, passes through the illumination lens 12 in that state, and is further longitudinally directed by the cylinder lens portion 13 on the emission surface side. It is condensed and emitted as illumination light L that is horizontally long in the reading width direction. The illumination light L is emitted as parallel light that does not spread (very little) in the vertical direction.

  At this time, since the condensing spherical lens portion 14 corresponding to each of the three LEDs 11 is provided on the incident surface side of the illumination lens 12, the light from all the LEDs 11 is efficiently converted into the illumination light L. In addition, it is possible to employ the high-intensity LED 11 having a wide directivity angle. As a result, it was possible to obtain the illumination light L that is bright near and far from the reading port 2a and has an appropriate (uniform) illuminance distribution in the lateral direction.

  Since the illumination lens 12 of this embodiment includes the spherical lens portion 14 on the incident surface side, unlike a lens using a lenticular lens, a fine shape is not required and a relatively simple lens shape can be used. Can do. Accordingly, the mold shape for molding the illumination lens 12 becomes simple, the life of the mold can be extended, and the manufacturing cost of the illumination lens 12 can be reduced. In addition, unlike the case where a plurality of lenses are used, only one illumination lens 12 can be used, so that it can be arranged in the main body case 2 in a compact manner, and the configuration is complicated and the entire apparatus is enlarged. Can be suppressed.

  As described above, according to the present embodiment, the illumination lens 12 constituting the illumination optical system 4 is integrally provided with the spherical lens portion 14 corresponding to each LED 11 on the incident surface side, and the cylinder lens portion on the emission surface side. 13 is provided as an integral unit, so that it is possible to obtain the excellent effect that the configuration of the illumination optical system 4 can be completed easily and inexpensively while the illumination light L can be efficiently emitted with high luminance. it can. In addition, a high-brightness LED 11 having a wide directivity angle can be employed as the illumination light source.

  In the above embodiment, each LED 11 is arranged at the focal position of the illumination lens 12. However, each LED may be arranged between the illumination lens and the focal position of the illumination lens. Well, according to this, it is possible to obtain illumination light that expands toward the destination. In the above embodiment, the spherical lens portion 14 is provided on the incident surface side of the illumination lens 12. However, the spherical lens portion 14 is not limited to a spherical surface, and may be an aspherical surface (for example, a curved surface that draws a parabola). Various shapes can be adopted as long as the lens shape condenses light from each LED. In addition, the present invention can be implemented with appropriate modifications within a range that does not depart from the gist, such as only an example of the number of LEDs and the directivity angle.

The top view which shows one Example of this invention, and shows the structure of an illumination optical system part roughly Rear view (a), plan view (b), side view (c) showing the configuration of the illumination lens Longitudinal side view showing the internal structure of the tip side of the barcode reader The figure which shows a mode that the illumination light is irradiated to the reading object roughly Diagram showing the relationship between lens curvature and focal length

Explanation of symbols

  In the drawings, 1 is a barcode reader (optical information reader), 2 is a body case, 4 is an illumination optical system, 5 is a light receiving optical system, 9 is a light receiving sensor, 10 is an imaging lens, and 11 is an LED (illumination light source). ), 12 is an illumination lens, 13 is a cylinder lens unit, 14 is a spherical lens unit, L is illumination light, and R is a reading target.

Claims (4)

An optical information reading apparatus having an illumination light source and an illumination lens, and having an illumination optical system that irradiates illumination light toward a reading target on which an information code is written,
The illumination light source is configured to include two or more LEDs,
Said illumination lens is on the incident side, the light emitted from these LED in respectively opposite to each LED provided with a lens shape for focusing, on the emission surface side, reading the incident light of the information code width An optical information reading apparatus comprising a lens shape that condenses light in a direction perpendicular to a direction. Incident side of the illumination lens, said by respectively opposite each LED, the optical according to claim 1, characterized in that it is configured into a spherical or aspherical curved to be convex on their LED side Information reader.   3. The optical information reader according to claim 1, wherein each of the LEDs is disposed at a focal position of the illumination lens.   3. The optical information reader according to claim 1, wherein each of the LEDs is disposed between the illumination lens and a focal position of the illumination lens.

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