JP2002125096A - Optical information reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information reading device capable of reducing the costs of a light source. SOLUTION: This optical information reading device is provided with an LED11 as the light source of the optical information reading device 1, and the LED11 is constituted as a current constriction type LED. A light emitted by an LED11a and a light emitted by an LED11b are respectively spread like a line by illuminating lens 12a and 12b. When a light is spread in this was in a conventional LED, the light is dispersed, and the role of a maker is impaired due to darkness. However, the directivity is high, and a light emission output is relatively large in this current constriction type LED so that a line- shaped illumination/marker line 3 can be formed on a bar code. Therefore, it is possible for an operator to perform positioning with the bar code by viewing this illumination/marker line 3. Also, the reflected light as a non- coherent light is image-formed through an image pickup lens 13 on an optical sensor 14 so that optical information reading can be performed. Thus, the illumination and marker can be obtained from the same current constriction type LED11 so that the costs can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information reading apparatus for reading optical information from a reading object on which optical information such as a bar code is described, and more particularly to an optical information reading apparatus capable of reading optical information at a position distant from a reading opening. The present invention relates to an information reading device.

[0002]

2. Description of the Related Art For example, a bar code attached to a product or the like is irradiated with reading light using a light emitting element such as a light emitting diode (LED) as a light source, and the light receiving element is arranged with the reflected light. There is known an optical information reading apparatus which forms an image on an optical sensor and reads an image of the barcode. Usually, such an optical information reader irradiates a bar code with reading light (illumination light) in a state where a reading port provided in a case of the optical information reader is almost in contact with the bar code. The reflected light is guided from the same reading port into the case of the optical information reading device, and forms an image on the optical sensor.

In such an optical information reading apparatus, it is necessary to bring the optical information reading apparatus to a product to which a bar code is attached, so that there is a problem that the reading operation is troublesome. In order to solve this problem, not only a barcode existing near the reading opening of the optical information reading apparatus but also a barcode distant from the vicinity of the reading opening by several tens of cm (for example, 30 to 50 cm) is connected to the light receiving means. By imaging and reading, without performing the operation of bringing the optical information reading device closer to the product every time reading is performed,
A so-called large-depth optical information reader that can efficiently read a barcode is conceivable. When reading a bar code located at such a distance, it is considered that guide light (marker light) indicating a readable range is irradiated.

Conventionally, an LED is used as a light source for reading light and guide light, as in an optical information reading apparatus described in, for example, Japanese Patent Application Laid-Open No. 5-242279. However, when an LED is used as the light source of the guide light, there is a problem that the LED light becomes invisible when the surrounding illuminance is high, and does not function as the guide light. One of the causes is LE
Low directivity when D is used. Therefore, it is conceivable to use a laser beam having high directivity (see, for example, JP-A-62-6117). In this case, even if the surrounding illuminance is high, the guide light by the laser light is easily seen.

However, when the reading light and the guide light are realized by the laser light, the following problem occurs. That is, laser light causes interference because of high coherence. When the laser light scatters on the rough surface, a random pattern (bright and dark) is formed by interference. This is called speckle, and this speckle causes a rough surface (for example, a surface on which a bar code exists) on the optical sensor.
Irrespective of the black and white, light and dark due to interference are converted into electrical signals, resulting in noise. For this reason, when laser light is used as the reading light,
The S / N ratio of the electric signal corresponding to the bar code output from the optical sensor decreases, and the reading performance decreases.

In order to prevent such inconvenience, appropriate reading is realized by using a non-coherent light emitting element as a light source of reading light and a laser light emitting element such as a laser diode as a light source of guide light. Meanwhile, it is conceivable to ensure the effectiveness as the guide light. This example is shown in FIG.

FIG. 5 is a schematic explanatory view showing a part of an internal structure of a head portion of an optical information reading apparatus as a conventional example.
FIG. 5A is a diagram viewed from the top, and FIG. 5B is a diagram viewed from the side. As described above, the reading unit includes two light emitting diodes (LEDs) 1 for emitting reading light.
1, an illumination lens 12 provided corresponding to each of the LEDs 11a and 11b, an imaging lens 13, and an optical sensor 14.
, A mirror 15, a laser diode 60, a laser mirror 61, and a laser lens 62.

The reading light is light that causes the LED 11 to emit light, is condensed by the illumination lens 12, and is reflected by the mirror 15. The reading light irradiates the bar code outside the case 2, and the light reflected by the bar code enters the case 2 again. Then, the reflected light is reflected by a mirror 15 and is incident on an imaging lens 13 provided with a stop (not shown) on the front surface, and is imaged by an optical sensor 14. The optical sensor 14 receives the reflected light from the bar code, and outputs the reflected light to the data processing output unit as an electric signal indicating the intensity of the light.

On the other hand, the guide light is emitted from the laser diode 60.
The laser beam is reflected by the laser mirror 61 and expanded in a line by the laser lens 62 to form a marker line 51 indicating a readable range on the barcode.
In this way, LEDs that do not cause speckle problems
The reading light from 11 and the guide light from the laser diode 60 having extremely high directivity and high visibility can be obtained on the barcode. If the optical axis (sensor optical axis) when the reflected light from the barcode forms an image on the light receiving surface of the optical sensor 14 matches the optical axis of the guide light, the range indicated by the guide light is the readable range. Can be matched perfectly.

However, in practice, it is necessary to prevent the reflected light from the bar code from blocking the optical path until it forms an image on the light receiving surface of the optical sensor 14, so that a deviation between both optical axes does not occur. Inevitable. This displacement is minimized by adjusting the above-described laser mirror 61 and the like.

However, if both the reading light by the LED and the guide light by the laser are generated as described above, the apparatus becomes expensive. Further, an adjusting mechanism and an adjusting operation for making the light emitted from each light source coincide with the optical axis of the imaging optical system are required, and the number of working steps increases, which causes a significant cost increase.

Accordingly, the present invention provides an optical information reading apparatus capable of performing reading while using the same light source as the marker light source and the guide light source without causing the above-mentioned problems.

[0013]

According to the optical information reading apparatus of the first aspect, which has been made to achieve the above object, the reading light is non-coherent light. No speckle problems occur. That is, the S / N ratio does not decrease and the reading performance does not decrease. In addition, since the guide light is emitted from a point light source, the guide light is excellent in directivity. Even if the distance between the portion of the optical information reading device that emits the guide light and the object to be read is large, the guide light is difficult to diffuse, so that the user is The reading range can be easily recognized.

Note that a substantially point light source is a light source that can be regarded as a point light source. That is, L which emits diffused light, which has been conventionally used as a light source of an optical information reader, is generally used.
Instead of ED, it is close to the directivity of laser light. The light emitting element may be one element or a plurality of elements. The guide light may be called marker light, and the reading light may be called illumination light.

In this way, it is possible to solve the problem of speckle that occurs when a laser is used as reading light, while having high directivity like a laser. In addition, since the reading light and the guide light are emitted from the same light source, there is no cost for adjusting the optical axis that occurs when the reading light and the guide light are generated from different light sources. Therefore, design, manufacture, maintenance, and the like can be performed without increasing costs.

It is to be noted that such a guide light must be of such a level that the subject performing the alignment can recognize the guide by the guide light. Therefore, the light emitting element must have a larger light output than an LED for generating reading light in a conventional optical information reading device.

As a light emitting element functioning as such a non-coherent substantially point light source, for example, a current confinement type light emitting diode is cited. A current confinement type light emitting diode (current confinement type LED) emits non-coherent light unlike a laser because it is an LED.
Further, the directivity is high and the output is higher than that of the LED in the conventional optical information reading device. Therefore, unlike the reading light by the LED of the conventional optical information reading device, the possibility that the light is diffused and becomes invisible is reduced, and the problem of speckle does not occur. Can be.

Further, since a laser is a coherent light having a very high directivity, it may be dangerous if the laser light is directly seen into the eyes, and safety standards and the like are set. Moreover,
Lasers generally have a shorter lifetime and are more fragile than LEDs. Therefore, although design and maintenance costs were high,
By using the current confinement type light emitting diode, these costs can be avoided.

Further, in the LED of the conventional optical information reading apparatus, it is necessary to condense the diffused light emitted from the element, and the resin or the like which molds the element is configured to perform the lens function. It is necessary to design the optical system of the optical information reading device in consideration of the above characteristics. However, according to the current confinement type light emitting diode, even if the mold does not have a lens function, it is possible to collect light outside the LED and obtain sufficient directivity. Therefore, such LE
The use of D makes it easy to design an optical system in the optical information reading device. That is, since the current confinement type light emitting diode has higher directivity than a general LED and can be regarded as a substantially point light source, it is easy to determine the position of the light source, and it is easy to condense and diffuse the light in the intended state. is there.

The reading light and the guide light may be generated in a line as described in claim 3. In this way, reading can be performed by adjusting this line to the object to be read. Therefore, for example, a one-dimensional barcode can be read smoothly.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. It is needless to say that the embodiments of the present invention are not limited to the following examples, and can take various forms as long as they belong to the technical scope of the present invention.

FIG. 1 shows an optical information reading apparatus 1 as an embodiment.
FIG. 1 is a schematic explanatory view showing an internal structure of a head portion of FIG.
FIG. 1A is a view in which a part is omitted and viewed from above, and FIG.
(B) is the figure seen from the side. FIG. 2 is a block diagram of the control system. Various components for reading (hereinafter, referred to as a reading device) are provided at a front portion in a case 2 provided in the optical information reading device 1.
It is referred to as a “reading unit” as appropriate. ) Is arranged, and a rear portion of the case 2 forms a grip portion (not shown) for the operator to hold by hand. A reading port 22 that is long in the left and right directions (in the direction perpendicular to the paper surface in FIG. 1B), that is, is long in the width direction, is provided in the lower front part of the case 2. In addition, a dustproof plate (not shown) is disposed behind the reading port 22 to close the reading port 22. This prevents dust from entering the case 2 from the reading port 22. In addition, the dust-proof plate can transmit light.

The reading unit is a light emitting diode (LE)
D) 11, an illumination lens 12, an imaging lens 13, an optical sensor 14, and an LED drive circuit 16 (see FIG. 2).
And a mirror 15. In this embodiment, L
The ED 11a and the LED 11b correspond to “light emitting elements”,
These are arranged on both sides of the imaging lens 13, respectively, and each LED 11 (hereinafter referred to as LED 11 when both LEDs are not distinguished, and LE 11 when distinguished)
D11a or LED11b. Also, codes other than LEDs are handled in the same manner. 2), an illumination lens 12a and an illumination lens 12b are provided.

When the LED 11 emits light under the control of the data processing output unit, which will be described later, the light reflected by the mirror 15 passes through the dustproof plate and irradiates the bar code 4 (see FIG. 2) outside the case 2. And bar code 4
The light reflected by the mirror enters the case 2 again from the dustproof plate, is reflected by the mirror 15, enters the imaging lens 13 having a not-shown aperture on the front surface, and passes through the imaging lens 13 to be optically reflected. An image is formed by the sensor 14. In the optical sensor 14, the light receiving elements are linearly arranged in one line, and the image of the bar code 4 is arranged on the light receiving element in the arrangement direction of each bar (the length direction of the bar code 4 (in the claims). The image is formed in the same direction as the “longitudinal direction of the light receiving surface”)) and the arrangement direction of the light receiving elements. Optical sensor 1
4 receives the reflected light from the bar code 4 and outputs it to the data processing output unit as an electric signal indicating the intensity of the light.

The image forming optical system including the mirror 15 and the image forming lens 13 has at least the position of the reading opening 22 and several tens cm (for example, 30 to 50 cm) from the position of the reading opening 22.
cm) It is configured as a deep imaging system so that the bar code 4 up to a distant position can be read.

Next, the configuration of the data processing output unit will be described. On the main board (not shown) inside the case 2,
As shown in FIG. 2, a waveform shaping circuit 17, a microcomputer 18, a memory 19, a reading confirmation device 20, and an output circuit 21 to a main unit such as a register and a host computer are provided. When the read data of the bar code 4 is input from the reading unit via the waveform shaping circuit 17, the data processing output unit decodes (decodes) the data by processing of the microcomputer 18.
The information represented by the barcode 4 is obtained, and the information is temporarily stored in the memory 19. Next, the information stored in the memory 19 is output by the output circuit 21 at a predetermined timing.
The data is transmitted to the main unit by wireless communication using light or radio waves or by wire.

A buzzer and a reading confirmation L are provided at a position where the reading unit is stored so as not to affect the optical path.
A reading confirmation device 20 composed of an ED is provided, and when the barcode 4 is successfully decoded by the microcomputer 18, the reading confirmation device 20 is driven to notify that decoding was successful by sound and light. Although not shown, a battery as a power supply is also housed in the case 2. The microcomputer 18 has a CPU, ROM, R
It has an AM, an I / O, etc., and performs the necessary processing as the data processing output unit described above.

Next, the illumination lens 12 will be described.
The illumination lens 12 is a lens for spreading the light emitted from the LED 11 in a fan shape and irradiating the bar code 4 with a linear illumination / marker line 3 indicating a readable range. The illumination lens 12 is a resin lens integrally formed of a transparent resin, and has an elongated shape in the left-right direction of the case 2.

Next, the LED 11 will be described. LED
Reference numeral 11 denotes a light emitting diode that emits visible light (for example, red). As shown in FIG. 3, a multilayer reflective film 72, a first clad layer 73, an active layer 74, a second clad layer 75, An ion implantation region 76 and an electrode 77 are sequentially formed, and an electrode 78 is formed on the lower surface of the substrate 71.

The electrode 77 has a substantially circular through-hole having a diameter of several tens of micrometers at the center of the surface, and forms a light extraction portion 79 serving as a window through which light is transmitted. And the active layer 7
The light generated in step 4 is output from the light extraction unit 79, so that the light can be regarded as a point light source, and high directivity can be obtained.

A conventional optical information reading apparatus uses an LED having a structure as shown in FIG. With this LED,
Light generated at the junction between the n region 92 and the p region 93 is emitted outside from the entire portion of the upper surface of the p region where the electrode 94 is not formed. This portion (light extraction portion 96) is several hundred micrometers square, and emits light from the entire surface of this portion. Therefore, since it becomes diffused light and has low directivity, even if it is used as a marker light of the optical information reading device 1,
As the distance from the bar code to be read increases, the light spreads and becomes dark like the illumination light 50 shown in FIG.
However, according to the LED having the structure shown in FIG. 3, it is possible to obtain a line-shaped bright light having high directivity like the illumination / marker line 3 shown in FIG. The light as the illumination / marker line 3 corresponds to “reading light” and “guide light”.

Since the light from the LED 11 is used as marker light, it is desirable that the output be high. Therefore, FIG.
In the LED shown in (1), the light emission output is increased by a double hetero structure in which the active layer 74 is sandwiched between the first clad layer 73 and the second clad layer 75. Further, a multilayer reflective film 72 (Bragg reflective film or the like) is provided, and among the light generated in the active layer 74, the light directed toward the substrate 71 is reflected toward the light extraction portion 79 to increase the light emission output.

In order to further increase the light emission output, the LED 11 is preferably an LED having a current confinement structure. Such a current-confined-type LED has a current-confined structure for limiting a current-carrying region in the active layer to a part of the plane thereof, and emits light in a light-emitting region provided in a part of the active layer. Is emitted from a light extraction portion provided in a part of the element. Therefore, the light emitting region can be limited, and higher light output can be obtained.

FIG. 4 shows an example of such a current confinement type LED.
FIG. FIG.
The external shape of the current confinement type LED of (a) and FIG. 4 (b) is a substantially rectangular parallelepiped substantially similar to the LED of FIG. 3, and a light extraction portion which is a substantially circular window having a diameter of several tens of micrometers on the upper surface. 79 is provided.

In the current confinement type LED shown in FIG. 4A, a current blocking layer 80 constituting the same surface as the electrode 77 is provided between the first cladding layer 73 and the substrate 71, and the center of the surface of the active layer 74 is provided. The current is constricted in the part. 4B, the current is confined by providing a current block layer 80 around the active layer in the same plane as the active layer 74. By doing so, the light emission output can be further increased.

As described above, the LED 11 has a light emitting portion having a diameter of about several tens of micrometers, which is equivalent to that of a laser, and has been devised to increase the output by the multilayer reflective film 72 and the current confinement structure described above. Is higher than the LED used in the conventional optical information reading apparatus. Also,
Since the light source can be regarded as a substantially point light source, the directivity can be easily enhanced by an exterior device such as the illumination lens 12. Therefore, even when reading the barcode 4 described on a distant reading target, the illumination / marker line 3 indicating the readable range can be easily visually recognized. Unlike the laser, the LED 11 has a light emission wavelength that is not a single wavelength but a light having a half-width spectrum with respect to the peak wavelength, and has poor coherence. Therefore, it can be used as illumination light because there is no problem of speckle.

Thus, as described with reference to FIG. 1, the illumination light and the marker light can be generated from the same LED 11 and used as the illumination / marker line 3. Therefore, the laser which is the conventional marker light source is unnecessary, and the illumination optical axis and the marker optical axis coincide with each other, so that costs in each stage of design, manufacturing, and maintenance that take into consideration parts, optical axis alignment, safety aspects, etc. Therefore, the cost can be significantly reduced, and a user-friendly optical information reading apparatus can be provided.

It should be noted that the LED 11 is the same as that shown in FIGS.
Not only the LED having the above structure but also an LED having a structure that can be regarded as a point light source may be used. Especially the current constriction type LE
D is good. In the present embodiment, the optical information reading apparatus for reading a bar code is described. However, for example, an optical information reading apparatus for reading characters may be used. Also in this case, since the marker light and the illuminating light coincide with each other, the alignment can be easily performed, and the character can be read smoothly.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing an internal structure of a head portion of an optical information reading device according to an embodiment.

FIG. 2 is a block diagram of a control system of the optical information reading device of the embodiment.

FIG. 3 is a schematic explanatory diagram illustrating an example of a configuration of an LED of the optical information reading device according to the embodiment.

FIG. 4 is a schematic explanatory diagram illustrating an example of a configuration of an LED of the optical information reading device according to the embodiment.

FIG. 5 is a schematic explanatory view showing an internal structure of a head portion of a conventional optical information reading device.

FIG. 6 is a schematic explanatory view showing a configuration of an LED of a conventional optical information reading device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical information reading device 2 ... Case 3 ... Illumination / marker line 4 ... Barcode 11a, 11b ... LED 12a, 12b ... Illumination lens 13 ... Imaging lens 14 ... Optical sensor 15 ... Mirror 16a, 16b ... LED drive circuit 17 Waveform shaping circuit 18 Microcomputer 19 Memory 20 Reading confirmation device 21 Output circuit 22 Reading port 50 Illumination light 51 Marker line 60 Laser diode 61 Laser mirror 62 Laser lens 71 Substrate 72 Multi-layer reflective film 73 First cladding layer 74 Active layer 75 Second cladding layer 76 Ion implantation region 77, 78 Electrode 79 Light extraction unit 80 Current blocking layer 91 n substrate 92 n region 93 ... p region 94,95 ... electrode 96 ... light extraction part

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5B072 AA00 BB00 CC24 CC38 DD02 JJ11 LL07 LL13 LL18 5C072 AA01 CA05 CA09 DA02 LA14 RA07 5F041 AA42 CB02 EE12

Claims (3)

[Claims] An optical information reading apparatus for reading optical information by irradiating a reading light for reading a reading target on which optical information is written and a guide light indicating a readable range, wherein the non-coherent substantially point light source is provided. An optical information reading apparatus, wherein the guide light is obtained from a light emitting element functioning as a light source, and the guide light is used as the reading light. 2. The optical information reading apparatus according to claim 1, wherein said light emitting element is a current confinement type light emitting diode. 3. The optical information reading apparatus according to claim 1, wherein the guide light and the read light are generated by expanding the guide light in a line shape in the longitudinal direction of the light receiving surface.