JPH11120279A - Optical information reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To calculate the distance to an object to be read without providing a distance sensor specially for a large-depth optical information reader which can reads optical information out of even an object at a distance from a read opening. SOLUTION: The reference image size Wst when there is a bar code Bst of size W at the read opening is represented as Wst=(L3/L2)W and image size Wo corresponding to a bar code Bo of size W at a distance L from the read opening is represented as Wo=(L3/(L1+L2))W, where L2 is the distance from the read opening to an image forming lens 34 and L3 is the distance from the image forming lens 34 to an optical sensor 36. The W's are erased from both the equations to calculate L1, which is then represented as ((Wst/ Wo)-1)L2. Here, L2 is a value characteristic of the device, so the distance L1 of the bar code Bo as an object of distance calculation from the read opening can be calculated by knowing Wst and No.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of irradiating an object to be read such as a bar code with light and reading an image of the object to be read from its reflected light. It relates to a possible optical information reader.

[0002]

2. Description of the Related Art A reflected light of light emitted from a light emitting means such as a light emitting diode onto a bar code attached to a product or the like is imaged on a light receiving means in which light receiving elements are arranged. 2. Description of the Related Art An optical information reading device that reads an image of a barcode is known.

Usually, such an optical information reading apparatus transmits light from a light emitting means through a reading port while a reading port provided in a case of the optical information reading apparatus is almost in contact with the bar code. , And the light reflected from the bar code is guided into the case of the optical information reading device from the same reading port, and forms an image on the light receiving means.

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 bar code existing near the reading opening of the optical information reading device but also a bar code distant from the vicinity of the reading opening by several tens cm (for example, 30 to 50 cm) to the light receiving means. By imaging and reading, without having to perform the operation of bringing the optical information reading device closer to the product for each reading,
A so-called large-depth optical information reader that can efficiently read a barcode is conceivable.

However, a bar code irradiating lens is set so that the light emitted from the light emitting means used in a normal bar code is radiated from the entire reading opening. This is because when reading a bar code almost in contact with the reading port, the case of the optical information reading device becomes a blind spot and the bar code becomes difficult to see. This is to ensure that the light beam strikes the bar code even if it is slightly displaced. But,
When the barcode irradiating lens is set so as to spread the irradiation light so as to irradiate from the entire reading opening in this manner, only a very weak light reaches the position of the barcode far from the reading opening, and the barcode is not illuminated. It is not clear whether the reading port is directed to the bar code to be read or not, and there is a risk that reading may be mistaken.

In order to solve this problem, the intensity of the reflected light incident on the light receiving means is detected, and the exposure time of the light receiving means is controlled based on the detection result. It has been considered that the amount of reflected light is always stabilized. With this configuration, the optical information can be read without bringing the reading opening into contact with the reading target, and the readable range of the optical information can be increased as the reading opening is separated from the reading target. In addition, a wide range of optical information can be read without being limited by the diameter of the reading port.

[0007] By the way, as a cause of lowering the reading performance when the reading port is separated from the reading object, not only the above-mentioned reduction of the reflected light intensity but also the problem of the illuminance distribution.
That is, as shown in FIG. 4A, no matter how flat the illuminance distribution of the irradiation light from the light emitting unit is, when the reflected light is imaged on the light receiving element through the imaging lens,
The amplitude of the reflected light waveform decreases as going to the periphery. This is based on the COS ⁴ law of the imaging lens, MTF specification, and the like.

In this regard, conventionally, for example, the light emitting means has been designed so that the illuminance distribution of the irradiation light is brighter in the periphery than in the center. For example, assuming that four light emitting diodes are arranged as light emitting means, the both ends of the reading port are made denser than the central part, or the irradiation direction of the four light emitting diodes is inclined to both ends of the reading port. Accordingly, a device for increasing the luminance of the peripheral portion of the reading target has been considered.

[0009] However, these methods can only cope with a case where a bar code to be read exists at a specific position. That is, the degree to which the amplitude of the reflected light waveform decreases as it goes to the periphery changes according to the change in the distance between the reading port and the barcode. Therefore, even when the arrangement and the light amount of the light emitting diodes are adjusted so that an appropriate illuminance distribution is obtained in a state where the distance between the reading port and the barcode is α, the distance between the reading port and the barcode does not increase when actually reading. If it changes to β, there is a possibility that the illumination distribution will not be appropriate in that state.

Therefore, as a method of executing control corresponding to the illuminance distribution that changes according to the distance between the reading port and the barcode, control data corresponding to the distance may be stored in advance. For example, the light amount control value for each light emitting diode when the image forming state by the light receiving unit is appropriate in the width direction of the reading port when the reading port has a sampling barcode, and the distance α (> 0) from the reading port. A light amount control value when there is a sampling barcode at the position, a light amount control value when there is a sampling barcode at a position β (> α) from the reading port, and so on.
Light amount control values are stored in correspondence with a plurality of sampling positions where the distance from the reading port is sequentially changed. At the time of the actual reading operation, the distance from the reading port to the barcode is measured by any method, and the control is executed by reading the light amount control value corresponding to the measured distance to the barcode. is there.

[0011]

However, conventionally,
A distance sensor has been used to measure the distance from the reading port to the barcode. As the distance sensor, for example, an active triangulation or a pyroelectric infrared sensor may be employed, but in any case, a process such as irradiating a light beam to the barcode is necessary. It is necessary to provide a configuration for distance measurement separately from a configuration for reading image data from the camera. Especially,
Assuming a handy type barcode reader, etc.,
Providing a configuration related to a distance sensor near the reading opening is not preferable because it leads to a complicated configuration and an increase in size.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a large-depth optical information reading apparatus capable of reading optical information even from a reading object located at a position distant from a reading port does not have a separate distance sensor. It is another object of the present invention to provide an optical information reading apparatus capable of calculating a distance to a reading target.

[0013]

In order to achieve the above object, the optical information reading apparatus according to the first aspect of the present invention is directed to an optical information reading apparatus, which irradiates light emitted from a light emitting means through a reading opening of the case. By irradiating the object to be read outside the case from, the reflected light from the object to be read forms an image on the light receiving means inside the case through the reading port, and the light receiving means reads the image of the object to be read. A reference image size storage unit that stores an image size of the reference read target in a state where the image is formed on the light receiving unit by reflected light from a reference read target arranged at a predetermined reference position. Image size detecting means for detecting an image size of the reading object in a state where the light is formed on the light receiving means by reflected light from the reading object at an arbitrary position; Based on the degree of enlargement or reduction of the image size of the read target detected by the image size detection unit with respect to the image size of the reference read target stored in the size storage unit, the distance to the read target at the arbitrary position is determined. And a distance calculating means for calculating.

According to the optical reading apparatus, the reference image size storage means stores the image of the reference reading object in an image formed on the light receiving means by the reflected light from the reference reading object arranged at the predetermined reference position. The image size is stored, and when the image size detection unit detects the image size of the reading target in a state where the image is formed on the light receiving unit by reflected light from the reading target at an arbitrary position, the distance calculation unit sets the reference image. The distance to the reading target at an arbitrary position is calculated based on the degree of enlargement or reduction of the image size of the reading target detected by the image size detection unit with respect to the image size of the reference reading target stored in the size storage unit.

The principle of this distance calculation will be described with reference to FIG. For example, a barcode Bst, which is an example of a reading target, is arranged in a reading port of an optical reading device, and the barcode Bs
It is assumed that the light reflected by t forms an image on an optical sensor 36 as a light receiving unit via an imaging lens 34. In this case, the image size Wst of the barcode Bst formed on the optical sensor 36 is stored as a reference image size. Then, at the time of the actual reading operation, for example, when the bar code Bo of the distance calculation target located at the position of the distance L1 from the reading port is read, the image size of the bar code Bo formed on the optical sensor 36 is Wo (<Wst). Assume that Assuming that the size W of the barcodes Bst and Bo itself does not change,
Wo <Wst applies to the bar code B for which the distance is to be calculated.
This is because o is separated from the reading port by the distance L1.

In FIG. 9, an image forming lens 34 is connected to a reading port.
L2 is the distance from the imaging lens 34 to the optical sensor 3
6, the reference image size Wst
Is expressed by the following equation using the size W of the barcode itself. Wst = (L3 / L2) W On the other hand, the barcode Bo located at the position of the distance L1 from the reading port.
The image size on the optical sensor 36 corresponding to
Is similarly expressed by the following equation using W.

Wo = {L3 / (L1 + L2)} W When W is eliminated from these equations, L2 · Wst = (L1
+ L2) The relationship of Wo is derived, and L1 is expressed by the following equation. L1 = {(Wst / Wo) -1} L2 Since the distance L2 is a value unique to the apparatus, if Wst and Wo are known, the distance L1 from the reading opening of the barcode Bo to be calculated can be calculated. . That is, the distance to the barcode can be obtained by using the original function of the apparatus for reading image data to be read such as a barcode without using a hardware configuration such as a distance sensor.

Conventionally, a distance sensor has been used to measure the distance from the reading port to the bar code. However, since processing such as irradiating a light beam to the bar code is required, image data from the bar code is required. It was necessary to provide a configuration for distance measurement separately from the configuration for reading the data.
In particular, assuming a handy-type barcode reader or the like, it is not preferable to dispose a configuration related to a distance sensor in the vicinity of the reading port because the configuration becomes complicated and large. In this regard, this device is a large-depth optical information reading device that can read optical information even from a reading object located far from the reading port. Can be calculated, which is very advantageous.

As described above, the distance is calculated using the degree of enlargement or reduction of the image size.
The representative width of the image to be read may be used.
As the representative width, for example, in the case of a barcode, the portion where the barcode symbol exists, that is, the distance from the start character to the stop character may be set as the representative width. Note that the object to be read by this apparatus may be a one-dimensional code such as a barcode or a two-dimensional code. In the case of a two-dimensional code, two widths, that is, a width in the vertical direction and a width in the horizontal direction, are detected. In this case, for example, a larger width may be used as a representative width.

As can be seen from the above description, the object to be read by this apparatus is limited to some extent. That is, the above-described distance calculation is based on the reference image size W
It is necessary that the image size of the “reference reading target” when st is stored is the same as the image size of the “reading target at distance calculation”. Therefore, it is very effective in the case of a reading target having the same standard and a constant size, such as a bar code attached to a mail.

When the reference image size Wst is stored, the "reference position" at which the reference reading object is arranged may be, for example, a reading port. Although an example has been given in the above description of the related art, the illuminance distribution changes or the illuminance decreases as the reading target such as a bar code moves away from the reading opening. Preferably, the distance is calculated.

By the way, as the control to be performed based on the distance calculated without using the distance sensor as described above, for example, light amount control for the light emitting means can be considered. For example, as described in claim 6, the light amount control value for the light emitting means when the image forming state of the light receiving means when the reference reading object is used has an appropriate illuminance distribution in the width direction of the reading opening is set to the reading opening. The light amount control value corresponding to the distance to the object to be read calculated by the distance calculation means is stored in correspondence with a plurality of sampling positions in which the distance from is sequentially changed, and light is emitted based on the light amount control value. The light amount control for the means is performed.

The case where the image forming state of the light receiving means is an ideal illuminance distribution is a state in which the illuminance distribution in the width direction of the reading opening is uniform (the amplitude of the reflected light waveform is uniform). As described above, no matter how flat the illuminance distribution of the irradiation light from the light emitting unit is, when the reflected light passes through the imaging lens and forms an image on the light receiving element, the COS ⁴ law of the imaging lens and the MTF Due to the characteristics and the like, the amplitude of the reflected light waveform decreases as it goes closer to the periphery. Therefore, in order to make the illuminance distribution uniform at the time of image formation on the light receiving means, roughly speaking, when viewed in the width direction of the reading opening, the illuminance of the illuminating light becomes brighter at the periphery than at the center when viewed in the width direction of the reading opening. It is necessary to control the light emitting means so as to obtain a distribution.

However, simply setting the light emitting means in a fixed manner so that the illuminance distribution of the illuminating light becomes brighter in the periphery than in the center only when the bar code to be read exists at a specific position. I can not cope. That is, the degree to which the amplitude of the reflected light waveform decreases as it goes to the periphery changes according to the change in the distance between the reading port and the barcode. This is due to the characteristics of the optical system (such as the degree of diffraction and image blur) and the surrounding environment. Therefore, even if the arrangement and the light amount of the light emitting diodes are adjusted so that an appropriate illuminance distribution is obtained when there is a distance from the reading port to the barcode, the distance between the reading port and the barcode does not increase when actually reading. If it changes, the appropriate illuminance distribution may not be obtained in that state.

Accordingly, the light amount control value for the light emitting means when the image forming state of the light receiving means is appropriate in the width direction of the reading port when the reading port has a reading target for sampling, and the distance α (>) from the reading port. 0) the light quantity control value when there is a sampling read target at the position, the light quantity control value when the sampling read target is at a distance β (> α) from the reading port, and so on. The light amount control values are stored in correspondence with a plurality of sampling positions where the distances are sequentially changed.

In the actual reading operation, the distance from the reading port to the object to be read is measured by the distance calculating means, and the control means controls the light amount control value corresponding to the measured distance to the object to be read. The light quantity is read from the value storage means, and the light quantity control for the light emitting means is performed based on the light quantity control value. In the actual reading operation, it is assumed that the distance h from the reading port to the reading target often does not match the distance α or β at the sampling position. For example, 0 <h ≦ In the case of α, the light amount control value at α may be used, and when α <h ≦ β, the light amount control value at β may be used. Further, the light quantity control values at other distances may be obtained by interpolation using the light quantity control values at the distances 0, α, and β.

The light amount control value stored in the control value storage means may be stored as a control value of the energy supplied to the light emitting means, or may be a time period during which the light receiving means can receive light. It may be stored as a control value of the light emitting time of the light emitting means within the band.

When the exposure time control for the light receiving means is also performed in addition to the light quantity control, the control value storage means may appropriately control the image forming state of the light receiving means when a reading object for sampling is used. Exposure time control values for the light receiving means in the case of realizing a large amount of received light may be stored corresponding to a plurality of sampling positions. This way,
The control unit reads a light amount control value and an exposure time control value corresponding to the distance to the reading target from the control value storage unit,
The light amount control for the light emitting means can be performed based on the light amount control value, and the exposure time control can be performed based on the exposure time control value.

When the exposure time of the light receiving means is limited by the shutter, the control value for opening the shutter may be stored in the control value storage means as the exposure time control value. In the case where the light amount control and the exposure time control are also performed with the amplification factor control for the amplifying unit, the control value storage unit may be configured to appropriately control the output from the light receiving unit when the reference reading target is used. High amplification factors are also stored corresponding to multiple sampling positions.
The control means may also be configured to read the amplification factor corresponding to the calculated distance to the reading target from the control value storage unit, and to control the amplification factor for the amplification unit based on the amplification factor.

[0030]

FIG. 1 is a schematic configuration diagram of an optical information reading device 4 as an embodiment to which the above-mentioned invention is applied. In the present embodiment, the optical information reading device 4
Is configured as a so-called barcode reader handy terminal. FIG. 1 is a schematic sectional view of the optical information reading device 4, and FIG. 2 is a block diagram of a control system thereof.

The optical information reading device 4 includes a case 12, a reading unit 14, a data processing output unit 16, and a power supply unit 18. The reading unit 14 is arranged inside the front part of the case 12, and the rear part of the case 12 forms a grip part 20 for the operator to hold with a hand. In the lower part of the front part of the case 12, a reading port 22 which is long in the left and right (in the direction perpendicular to the paper surface in FIG. 1), that is, is long in the width direction, is provided. , The reading port 22 is closed. As a result, the dust is
2 to prevent it from entering the inside of the case 12. Further, the dustproof plate 24 can pass at least red light as reading light described below.

The reading section 14 includes an illumination red light emitting diode 26 (corresponding to a light emitting means), a light emission driving circuit 28, a bar code irradiation lens 30, a reflecting mirror 32, an imaging lens section 34, and an optical sensor 36 (light receiving means). Applicable). When the illumination red light emitting diode 26 emits light by the light emission drive circuit 28, the red light passes through the dustproof plate 24 and irradiates the bar code 8 outside the case 12. In FIG. 1, the bar arrangement direction of the bar code 8 and the width direction of the reading port 22 are aligned, and the bar code 8 is almost in contact with the reading port 22 as shown by a solid line in FIG. The case where the bar code 8 is irradiated is shown. Of course, as shown by the broken line in FIG. 1, the reading may be performed with the reading opening separated from the barcode 8.

The red light reflected by the bar code 8 is
Again, the dust enters the case 12 from the dustproof plate 24, is reflected by the reflecting mirror 32, and is incident on the imaging lens unit 34 having a vertically long aperture (not shown) built therein. An image of the barcode 8 is formed on the optical sensor 36 in which light receiving elements are linearly arranged in a line via a lens in the same direction as the arrangement direction of each bar and the light receiving element of the optical sensor 36. Let it. The optical sensor 36 that has read the image of the barcode 8 by photoelectric conversion and outputs it to the data processing output unit 16 as an electric signal representing the pattern of the image.

The longitudinal aperture built in the imaging lens unit 34 is disposed closer to the reading port 22 than the imaging lens, and its longitudinal direction coincides with the longitudinal direction of the bar of the bar code 8. The bar code 8 is set to be read. The imaging system including the reflecting mirror 32 and the imaging lens unit 34 has at least the position of the reading opening 22 and several tens of cm (for example, 30 to 50 cm) from the position of the reading opening 22.
It is configured as an imaging system with a large depth so that the bar code 8 up to a distant position can be read.

The optical sensor 36 uses an image sensor for reading a document of a facsimile apparatus in which light receiving elements are arranged in a line and each light receiving element has an aspect ratio of approximately "1". Data processing output unit 1 inside case 12
6 includes an amplification circuit 41, a memory 42 (corresponding to a reference image size storage unit and a control value storage unit) on a substrate 38,
A value conversion circuit 43, a microcomputer 44 (corresponding to control means), and an output circuit 46 to a main unit such as a register and a host computer are provided. When the read data of the barcode 8 is input from the reading unit 14 via the amplifying circuit 41 and the binarizing circuit 43, the data processing output unit 16 decodes (decodes) the data by processing of the microcomputer 44. , The information represented by the barcode 8 is obtained, and the information is temporarily stored in the memory 42. Next, the information stored in the memory 42 is output to an output circuit 46.
Thus, a serial signal is transmitted to the main unit. In this embodiment, wired communication is used, but wireless communication using light or radio waves may be used.

In the portion where the reading section 14 is stored,
A buzzer device 48 is provided at a position not affecting the optical path,
When the microcomputer 44 succeeds in decoding the bar code 8, the buzzer device 48 sounds. In the power supply section 18, a battery 18a is housed as a power supply.

The microcomputer 44 has a well-known CP.
U, ROM, RAM, I / O, and the like are provided to execute necessary processing as the data processing output unit 16 described above. Here, the optical arrangement state is schematically shown in FIG. The illumination red light emitting diode 26 described in FIG. 1 is actually composed of four illumination red light emitting diodes 26a, 26b, 26c and 26d as shown in FIG.
Irradiation light from these is passed through the condenser lens 30 to the reading port 2.
From 2, the bar code 8 existing outside the case 12 is irradiated.

The red light emitting diodes 26a, 26 for illumination
Although b, 26c and 26d are arranged side by side in the width direction of the reading opening, both end sides of the reading opening 22 are made denser than the central portion. This is because the illumination light from the illumination red light emitting diodes 26a, 26b, 26c, 26d makes the illuminance at the peripheral portion larger than at the central portion on the bar code 8 to be read. As shown in FIG. 3B, the red light emitting diodes 26a, 26b, 26 for illumination are used.
It is also conceivable to incline the irradiation directions of c and 26d toward both ends of the reading port 22 so as to increase the illuminance in the peripheral portion of the reading target.

As described above, the red light emitting diode 2 for illumination
The reason that the illuminance of the irradiation light from 6a, 26b, 26c, and 26d on the bar code 8 to be read is higher in the peripheral portion than in the center portion is that the reflected light is no matter how flat the illuminance distribution of the irradiation light is. Is formed on the optical sensor 36 through the imaging lens unit 34, the imaging lens unit 3
This is to cope with the fact that the amplitude of the reflected light waveform decreases toward the periphery as shown in FIG. 4A due to the COS ⁴ law, MTF characteristics, etc.

However, these methods can only cope with a case where a bar code to be read exists at a specific position. That is, the degree to which the amplitude of the reflected light waveform decreases as it goes to the periphery changes according to the change in the distance between the reading port 22 and the barcode 8. Therefore, for example, as shown by a solid line in FIG.
Even if the adjustment is made based on the case where the bar code 8 is irradiated in a state where the reading port 22 is almost in contact with the reading port 22, it is inappropriate when the reading port 22 is separated from the bar code 8 as shown by a broken line in FIG. Becomes Therefore, when the reading port 22 is separated from the barcode 8, the illumination intensity distribution of the illumination light must be appropriately adjusted according to the distance.

In view of this point, in the present embodiment, the light emission drive circuit 28 is configured so as to be able to control the light amount of each of the illumination red light emitting diodes 26a, 26b, 26c, 26d. The light emission drive circuit 28 is, for example, as shown in FIG.
(26b, 26c, 26d) and a power supply Vcc, a limiting resistor R is provided, and a red light emitting diode 26a (2
6b, 26c, 26d), the transistor T
R is connected. The limiting resistor R and the transistor TR correspond to the light emission drive circuit 28. When the illumination red light emitting diode 26a (26b, 26c, 26d) emits light, the microcomputer 44 outputs an emission signal P to the transistor TR, so that the current is supplied to the illumination red light emitting diode 26a (26b, 26c, 26d). Flows to emit light.

Each illumination red light emitting diode 26a, 26
For example, when the light amounts of the four red light emitting diodes 26a, 26b, 26c, and 26d are equalized, the light amount control of the peripheral portions in the region D where the reflected light from the bar code 8 forms an image is performed. In the case where V1 is smaller than the output V2 at the center, for example, the light amounts of the two illumination red light emitting diodes 26a and 26d at both ends are reduced by the two illumination red light emitting diodes 26b at the center.
The control is made to be larger than 26c so that the output V3 in the peripheral portion becomes almost the same as the output V4 in the central portion as shown in FIG. 4B. The control in that case is
The exposure time of the light receiving element in the optical sensor 36 is shown in FIG.
Assuming T1 shown in (a), within the exposure time T1, for example, two illumination red light emitting diodes 26b for illuminating the center of the bar code 8 in FIG.
26c is turned on for the lighting time T2 shown in FIG. In this manner, in the light receiving element of the optical sensor 36, the light receiving element corresponding to the peripheral portion can store light longer than the light receiving element corresponding to the central portion by the time T1−T2, so that the lighting time T2 Is adjusted, the output V3 of the peripheral portion is adjusted as shown in FIG.
Is approximately the same as the output V4 at the center.

If the output from the optical sensor 36 is too small, the binarization circuit 43 does not properly binarize the data. As a result, the information of the bar code 8 cannot be read properly. Exposure time T1 in sensor 36
Is controlled to be longer. When the exposure time T1 is lengthened, the light receiving time of the light receiving element of the optical sensor 36 is lengthened, and the amount of accumulated charge is increased accordingly, so that the output level from the optical sensor 36 is increased as a whole. As described above, within the predetermined exposure time T1, the two illumination red light emitting diodes 26b and 26c for illuminating the center of the barcode 8 are turned on for the lighting time T2 shown in FIG. 6B. Therefore, if the exposure time T1 is increased, the lighting time T2 is also increased at the same rate.

These controls are executed based on the control values stored in the memory 42. More specifically, the illumination red light emitting diode 26 when the imaging state of the optical sensor 36 when the reading target for sampling is used has an appropriate illuminance distribution in the width direction of the reading opening 22.
The light amount control values (the lighting time T2 in this case) for a, 26b, 26c, and 26d, and the exposure time T1 when the output level from the optical sensor 36 becomes an appropriate value, and the distance L from the reading port 22 are In the actual reading operation, the lighting time T2 corresponding to the distance from the reading port 22 to the barcode 8 is read out from the memory 42 in correspondence with a plurality of sampling positions that are sequentially changed.
Control based on the control value is performed.

Therefore, in order to execute such control, it is necessary to obtain a distance from the reading port 22 to the bar code 8 during an actual reading operation. In the case of this embodiment, however, a distance sensor or the like is used. , And is calculated using image data read based on the reflected light from the bar code 8 that is the actual reading target.

The principle of this distance calculation has been described with reference to FIG. 9, but will be described here again based on the configuration of the present embodiment. In the optical information reading device 4 of the present embodiment,
As shown in FIG. 7, the distance from the reading port 22 to the imaging lens unit 34 is L2, and the distance from the imaging lens unit 34 to the optical sensor 3 is L2.
The distance to 6 is L3, and these values are known. The feature is that the distance L1 from the reading port 22 to the barcode 8 is calculated.

As can be seen from FIG. 9, the optical sensor 3 in the case where the reference bar code Bst is disposed in the reading opening 22
6, the width (reference image width) Wst of the image formed on the optical sensor 36 and the width of the image formed on the optical sensor 36 when the bar code Bo located at the position of the distance L1 from the reading port 22 (distance calculation target image) Assuming that the width Wo does not change the width W of both barcodes Bst and Bo itself, Wo <Wst occurs because the barcode Bo is separated from the reading opening 22 by the distance L1.

Then, these two image widths Wst, Wo
Is expressed by the following equation using the width W of the barcode itself. Wst = (L3 / L2) W Wo = {L3 / (L1 + L2)} W When W is eliminated from both equations, L2 · Wst = (L1
+ L2) The relationship of Wo is derived, and L1 is expressed by the following equation.

L1 = {(Wst / Wo) -1} L2 Since the distance L2 is a value unique to the apparatus, if Wst and Wo are known, the distance L1 from the reading port 22 to the bar code Bo can be calculated. . In other words, the distance to the barcode can be obtained by using the original function of the apparatus for reading the image data of the barcode without using a hardware configuration such as a distance sensor.

In this embodiment, a sampling label as shown in FIG. 8 is used as the reference barcode Bst in FIG. The width W1 of the white bar and the width W of the black bar of the barcode in this sampling label
2 are arranged at equal intervals of, for example, 1 mm or more, which are less affected by the characteristics of the optical system such as the degree of diffraction and the degree of image blur, and include two thick bars (the above-mentioned W
It is preferably at least twice as large as 1, W2. ) Forms an interval W smaller than the width of the reading port 22.

Next, a process for storing the above-described reference image width Wst and various control values will be described. This storage process is performed, for example, at the time of factory shipment. Since this is executed by the microcomputer 44, its processing is shown in FIG.
This will be described with reference to the flowchart of FIG.

When the process is started, first, the reading port 22 is
It is determined whether or not a sampling label (see FIG. 8) on which the reference barcode Bst (see FIG. 9) is printed (S110). For example, it is conceivable that the operator performing the initial setting gives an instruction by pressing an operation button (not shown). In this case, when the operation button is pressed, the setting is completed (S110: YES), and S1 is performed.
Move to 20.

In S120, the reference image width Wst is calculated. This is because the output from the optical sensor 36 based on the reflected light from the reference barcode Bst is amplified by the amplifier circuit 41, the amplified signal is binarized by the binarization circuit 43, and the binarized signal is Captured by microcomputer 44,
Thick bar of the above-mentioned reference barcode Bst (see FIG. 9)
By calculating the interval W. The calculated interval W is the reference image width Wst of the reference barcode Bst formed on the optical sensor 36.

Then, the calculated reference image width Wst and the known L2 and L3 are stored in the memory 42 (S1).
30). Thereafter, it is determined whether or not a sampling label (see FIG. 8) is arranged at a predetermined sampling position (S140). Similarly to the processing of S110 described above, for example, it is conceivable that the operator performing the initial setting gives an instruction by pressing an operation button (not shown). In this case, the setting is completed when the operation button is pressed ( S140: YES), and proceeds to S150. And
In S150, the exposure time T1 and the amplification factor corresponding to the sampling position are stored.

First, as for the sampling position, the distance from the reading port 22 is 0, that is, the predetermined maximum value max including the case where the sampling label is arranged in the reading port 22.
A sampling position may be set as appropriate, the sampling labels may be sequentially moved and arranged, and the completion of setting may be indicated each time by the operation button or the like.

In this case, with respect to the exposure time T1 and the amplification factor, it is conceivable that values required at the sampling position are set in advance and given from outside. Of course, it is also possible to determine whether decoding can be actually performed while changing the control value as in a lighting time T2 to be described later and select an appropriate value.

Next, in S160, the lighting time T2 is controlled. As described above, the illumination red light emitting diodes 26a, 26b, 26c, and 26d are turned on for the lighting time T2 shown in FIG. 6B and then turned off within the exposure time T1 of the light receiving element in the optical sensor 36. The control is executed at the time of reading. For example, two illumination red light emitting diodes 26b, 2 for illuminating the center of the bar code 8
6c is turned on for the lighting time T2 and then turned off.
If the light-receiving elements a and 26d are kept turned on, the light-receiving elements in the optical sensor 36 correspond to the light-receiving elements corresponding to the peripheral part more than the light-receiving element corresponding to the central part in time T1-T2.
Since the light can be accumulated for as long as possible, by adjusting the lighting time T2, as shown in FIG. 4B, the output V3 in the peripheral portion is made substantially the same as the output V4 in the central portion. Is possible.

Therefore, in S160, several lighting time T2 candidates are prepared for each of the illumination red light emitting diodes 26a, 26b, 26c, and 26d, and the combination of these is finally set. Since it is necessary to determine whether or not this setting is appropriate, it is determined in S170 whether or not decoding was successful.
Specifically, the illumination operation is performed at the above-described exposure time T1, the amplification factor, and the set lighting time T2, and the output from the optical sensor 36 based on the reflected light from the reference barcode Bst due to the illumination is amplified. The signal is amplified at 41, the amplified signal is binarized at a binarization circuit 43, and the binarized signal is decoded by a microcomputer 44 to determine whether or not the signal has been properly decoded.

If decoding is possible (S170: Y
ES), since the lighting time set in S160 is an appropriate value, the lighting time T2 is stored in S180, but if decoding was not possible (S170: NO), S1
Return to step 60 to set another combination.

As described above, when the processing up to S180 is completed, the red light emitting diodes 26a, 26b, 26c, 26d corresponding to the distance L1 at a certain sampling position, as shown in the control value table shown in FIG. The respective control values such as the lighting time T2, the exposure time T1, and the amplification factor are stored in the memory 42. Then, in S190, it is determined whether or not the storage of the control values corresponding to all the sampling positions has been completed, and if the storage has been completed (S190: YES).
Then, the present process is terminated, but if not terminated (S190: NO), the process returns to S140, and the control value storage process at another sampling position (S150 to S180) is executed.

When the processing of FIG. 10 is completed, the control value table of FIG. 11 is set corresponding to the distances L1 of all sampling positions. Next, the distance calculation and data fetch processing in the actual reading operation will be described with reference to the flowchart in FIG.

When the processing is started, first, the width Wo of the target image for calculating the distance is calculated (S210). This is because the output from the optical sensor 36 based on the reflected light from the bar code Bo whose distance is to be calculated is amplified by the amplifier circuit 41, the amplified signal is binarized by the binarization circuit 43, and the binary signal is output. The microcomputer 44 captures the digitized signal, and determines the portion where the barcode symbol exists, that is, the distance from the start character to the stop character, as the width Wo of the image for distance calculation.
Is calculated as

Then, using the image width Wo of the distance calculation target, the reading port 22 of the bar code Bo of the distance calculation target is used.
Is calculated (S220). As described above, this distance L1 is L1 = {(Wst / Wo) -1}.
L2. The distance L2 is a fixed value stored in S130 of FIG. 10 and the reference image width Wst is also stored in S130 of FIG. 10, so the distance calculation target image width Wo calculated in S210.
Is used, the distance L1 can be calculated.

Then, in S230, the control value corresponding to the distance L1 calculated in S220 is read from the control value table (see FIG. 11) in the memory 42. In S240, the illumination control is performed using the read control value. And perform data capture. That is, each of the illumination red light emitting diodes 26a, 26b, 2 shown in the control value table of FIG.
Lighting time T2 corresponding to 6c, 26d, optical sensor 3
The illumination operation is performed with the exposure time T1 in 6 and the amplification factor in the amplification circuit 41, the output from the optical sensor 36 based on the reflected light is amplified in the amplification circuit 41, and the amplified signal is sent to the binarization circuit 43. The microcomputer 44 performs a reading operation by decoding the binary signal by the microcomputer 44.

As described above, according to the optical information reading apparatus 4 of the present embodiment, the original function of reading the image data of the bar code 8 can be utilized without using a hardware configuration such as a distance sensor. The distance L1 from the reading port 22 to the barcode 8 can be obtained. Conventionally, a distance sensor was used to measure the distance from the reading port 22 to the barcode 8. However, since processing such as irradiating a light beam to the barcode 8 is required, the image from the barcode 8 is used. A configuration for distance measurement had to be provided separately from a configuration for reading data. In particular, assuming a handy-type barcode reader or the like, it is not preferable to dispose a configuration related to the distance sensor near the reading opening 22 because the configuration becomes complicated and large. In this regard, the optical information reader 4 is a large-depth optical information reader capable of reading optical information even from the barcode 8 at a position distant from the reading port 22, and has a separate distance sensor. This is very advantageous because the distance to the object to be read can be calculated without the need.

As can be seen from the above description, the object to be read by the optical information reading device 4 is limited to some extent. That is, the principle of the above-described distance calculation is that the distance W between the thick bars (see FIG. 8) of the reference barcode Bst (see FIG. 9) when the reference image width Wst is stored and the distance calculation target, that is, the reading target Bar code Bo (see FIG. 9) itself width W
Are assumed to be the same. Therefore, it is very effective in the case of a reading target having the same standard and a constant size, such as a barcode 8 attached to a mail.

As described above, the present invention is not limited to such an embodiment, and can be implemented in various forms without departing from the gist of the present invention. Although the optical information reading device 4 of the above-described embodiment is a reader for the bar code 8, it can be similarly configured for a two-dimensional code, and the same effect is obtained.

In the above embodiment, the bar code, such as the reference image width Wst or the distance calculation target image width Wo, is used as the image size when calculating the distance L1 using the degree of enlargement or reduction of the image size. The representative width of the image was used. This is because the object to be read is a one-dimensional code called a barcode.
When a two-dimensional code is assumed, a width in the vertical direction and a width in the horizontal direction are detected. In this case, for example, a measure may be taken such that the larger width is used as the representative width.

In the above embodiment, the "reference position" where the reference barcode Bst is arranged when the reference image width Wst is stored is set to the reading port 22, but the reference position can be realized in another position. However, the illuminance distribution changes or the illuminance decreases as the bar code 8 moves away from the reading port 22.
It is preferable to calculate the distance therefrom.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an optical information reading device as one embodiment.

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

FIG. 3 is an explanatory view showing an arrangement of a red light emitting diode for illumination of the optical information reading device.

FIG. 4 is an explanatory diagram of a reflected light waveform formed on an optical sensor.

FIG. 5 is a circuit diagram showing a luminance adjusting mechanism of a red light emitting diode for illumination of the optical information reading device.

FIG. 6 is a time chart showing an exposure time T1 of the optical sensor and a lighting time T2 of the illumination red light emitting diode.

FIG. 7 is an explanatory diagram illustrating a principle of calculating a distance.

FIG. 8 is an explanatory diagram of a sampling label.

FIG. 9 is an explanatory diagram showing a principle of calculating a distance.

FIG. 10 is a flowchart illustrating a process of storing a reference image width Wst and various control values.

FIG. 11 is an explanatory diagram of a control value table.

FIG. 12 is a flowchart showing a distance calculation and data fetch process in an actual reading operation.

[Explanation of symbols]

4: Optical information reading device 8: Bar code 1
2 Case 14 Reading part 16 Data processing output part
18 power supply unit 18a battery 20 grip unit
Reference numeral 22: Reading port 24: Dustproof plate 26 (26a, 26b, 26c, 26d): Red light emitting diode for illumination 28: Light emission drive circuit 30: Bar code irradiation lens 32: Reflecting mirror 34: Image forming lens 3
6 optical sensor 38 substrate 41 amplifying circuit 4
2 ... memory 43 ... binarization circuit 44 ... microcomputer 4
6 ... Output Circuit 48 ... Buzzer Device Bst ... Reference Barcode Bo ... Distance Calculation Target Barcode Wst ... Reference Image Width Wo ... Distance Calculation Target Image Width L1 ... Distance from Reading Port 22 to Distance Calculation Target Barcode Bo L2 ... Reading Distance from the opening 22 to the imaging lens unit 34 L3 ... Distance from the imaging lens unit 34 to the optical sensor 36

Claims (10)

[Claims] An illumination light from a light emitting means is irradiated from the inside of the case to a reading object outside the case through a reading port of the case, so that reflected light from the reading object is received inside the case through the reading port. An optical information reading apparatus that forms an image on a unit and reads an image to be read by the light receiving unit, wherein the image is formed on the light receiving unit by reflected light from a reference reading target arranged at a predetermined reference position. A reference image size storage unit that stores an image size of the reference read target in a state, and an image size of the read target in an image formed on the light receiving unit by reflected light from the read target at an arbitrary position. An image size detecting means for detecting, and an image size detecting means for the image size of the reference reading target stored in the reference image size storing means. Based on the enlarged or reduced degree of image size of the reading object detected I, an optical reading device, comprising a distance calculating means for calculating a distance to the reading object which is in the arbitrary position. 2. The optical information reading apparatus according to claim 1, wherein the image size is a representative width of the image to be read. 3. The apparatus according to claim 2, wherein the predetermined reference position is the reading opening, and the distance calculating means is configured to calculate a distance from the reading opening to the reading target at the arbitrary position. The optical information reading device according to claim 1. 4. The optical information reading apparatus according to claim 1, wherein the object to be read is a barcode. 5. The optical information reading apparatus according to claim 1, wherein the object to be read is a two-dimensional code. 6. A light amount control value for said light emitting means when an image formation state of said light receiving means when said reference reading object is used is an appropriate illuminance distribution in a width direction of said reading opening, A control value storage unit that stores a plurality of sampling positions in which the distance from the object is sequentially changed; and the control value storage unit that stores the light amount control value that corresponds to the distance to the reading target calculated by the distance calculation unit. The optical information reading apparatus according to any one of claims 1 to 5, further comprising: a control unit that reads from the unit and performs light amount control on the light emitting unit based on the light amount control value. 7. The optical information reading apparatus according to claim 6, wherein the light amount control value stored in the control value storage means is a control value of energy supplied to the light emitting means. 8. The light amount control value stored in the control value storage means is a control value of a light emission time of the light emitting means in a time zone in which the light receiving means can receive light. The optical information reading device according to claim 6, wherein: 9. An exposure time control value for the light receiving means when the imaging state of the light receiving means when the reference reading object is used is realized with an appropriate amount of received light. The control means reads out the exposure time control value corresponding to the calculated distance to the read target from the control value storage means, and stores the exposure time control value. 9. The optical information reading apparatus according to claim 6, wherein an exposure time control for the light receiving unit is performed based on the value. 10. An amplifying means for increasing an amplification factor of an output waveform of the light receiving means, wherein the control value storage means is an amplifying means for the output from the light receiving means when the reference reading object is used. The appropriate amplification factor is also stored in correspondence with the plurality of sampling positions, and the control unit reads out the amplification factor corresponding to the calculated distance to the read target from the control value storage unit, The optical information reading device according to any one of claims 6 to 9, wherein amplification factor control for the amplification unit is performed based on the amplification factor.