JP3120530B2 - Optical information reader - Google Patents

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 such as barcodes and OCR characters, and more particularly to a single apparatus for reading barcodes and OCR characters. And an optical information reading apparatus.

[0002]

2. Description of the Related Art Conventionally, there has been known an optical information reading apparatus which uses a two-dimensional area sensor made of a semiconductor such as a CCD in order to read a bar code and an OCR character and shares a light receiving means in reading. Have been. One example is shown in FIG. As shown in the figure, an optical information reading apparatus 101 irradiates light by a scanning unit 103 and reflects light reflected from a bar code 105 or an OCR character 106 on a light receiving unit 113 having a mirror 107, a lens 109, and an area sensor 111. Performs photoelectric conversion. And the light receiving means 11
3 is amplified by the amplifying means 115 and the signal processing means 1
After binarization at 17, information is obtained by restoring by the decoding means 119.

[0003] Decoding means 119 automatically determines from an external instruction or an information pattern read,
The barcode 105 and the OCR character 107 are restored as needed. For example, a narrow bar and a wide bar are determined by measuring the width of a binarized signal, and the barcode 105 is restored based on the narrow bar and the wide bar. Also, the OC unit serving as a reference in the decoding means 119
The R character is stored in advance, and the binarized signal and the reference OCR character are subjected to pattern matching to obtain an OC.
The R character 106 was restored. In addition, OC mentioned here
Restoring the R character 106 includes functions such as cutting out and recognizing a character area.

In the optical information, the bar code 105
Can be read by a one-dimensional line sensor,
The OCR character 107 needs to be read by the two-dimensional area sensor 111, and the barcode 105 and the OCR character 107 are read.
In order to read (1) and (2) by one machine, the two-dimensional area sensor 111 is necessary as described above.

[0005]

However, as described above, in the conventional optical information reading apparatus, the OCR
Since the area sensor 111 is used for the light receiving means 113 because the character 106 needs to be read, the following inconvenience occurs. That is, in a normal bar code reader, like the line sensor 121 shown in FIG.
In many cases, the shape of the light receiving pixel is rectangular, and the light receiving pixel 121a is elongated in a direction perpendicular to the light scanning direction. For this reason, more reflected light from the barcode 105 can be received.

[0006] In contrast, the area sensor 111 is shown in FIG.
As shown in (A), square or area sensor 1
Considering the influence of the relative rotation angle between the optical information 11 and the optical information, the light receiving pixel 111 having an isotropic shape so that the change of the incident light is reduced.
You need to have a. Therefore, in the area sensor 111, a plurality of pixel lines in which a plurality of light receiving pixels 111a are arranged in the light scanning direction are arranged, and the number of the light receiving pixels 111a is smaller than the number of the light receiving pixels 121a in the case of the line sensor 121. More.

Accordingly, the light receiving area of one pixel is inevitably smaller than that of a normal bar code reader, and the level of the obtained photoelectric conversion signal is reduced. As a result, the reading sensitivity deteriorates, and sufficient reading performance cannot be obtained. Further, if the irradiation light amount in the scanning means 103 is increased or the gain in the amplifying means 115 is increased in order to improve the reading sensitivity, the former causes an increase in current consumption and uneven light amount, and in the latter case, the signal pair is increased. Sufficient reading performance cannot be obtained because the noise ratio is deteriorated.

The present invention has been made in view of such a problem, and an object of the present invention is to provide an optical information reading apparatus capable of obtaining a sufficient reading performance of optical information even when a two-dimensional area sensor is used. The purpose is.

[0009]

That is, the present invention to achieve this object comprises scanning means for projecting and scanning light on an object on which optical information is described, and a photoelectric conversion element. A two-dimensional area sensor having a plurality of pixel lines in which a plurality of light receiving pixels are arranged in the scanning direction;
An optical system comprising: a light receiving unit that receives reflected light reflected from the object and outputs an electric signal corresponding to the amount of the received light; and a reading unit that reads the optical information based on the electric signal from the light receiving unit. An information reading device, which is provided in an electric signal path from the light receiving means to the reading means.
The output of the previous line is output to the output corresponding to the pixel line being scanned.
Add the output corresponding to the line, and
With output improving means for improving the output to the reading means
The output improving means is such that the scanning means includes the pixel array.
In the direction corresponding to the optical scanning cycle.
A delay element for delaying the air signal and an output from the light receiving means.
Adding means for taking the input electric signal as one input,
The other input of the adding means is output from the adding means.
The delayed electrical signal is delayed by the delay element.
And the electricity corresponding to the addition result by the adding means
By outputting a signal to the reading means,
The gist of the invention is an optical information reading apparatus characterized by realizing improvement .

[0010]

[0011]

In the optical information reading apparatus of the present invention configured as described above, the scanning means projects and scans light on an object on which optical information is described, and the light receiving means scans the light. As a result, the reflected light reflected from the object is received, and an electric signal corresponding to the received light amount is output. Then the electric signal from the light receiving means, the output increase means, the current
The image corresponding to the previous pixel is output to the output corresponding to the pixel line being scanned.
Output by adding the output corresponding to the elementary line
Is input to the reading means. And this
Output improvement is achieved by optical scanning in the pixel line direction with a delay element.
Is delayed by the delay amount corresponding to the cycle of
After being added to the delayed electric signal, the reading means
Is input to That is, the electric signal output from the light receiving means
, The signal level increases,
The light receiving sensitivity is improved. Therefore, the reading performance of optical information is also improved.

[0012]

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating a configuration of an entire optical information reading apparatus according to an embodiment to which the present invention is applied. As shown in FIG. 1, the optical system of the optical information reading apparatus according to the present embodiment scans a laser beam from a laser light source and projects it on a reading target 1 on which a bar code 1a or a well-known OCR character 1b is described. Scanning unit 3, area sensor 5 for generating an electric signal according to the amount of incident light, condensing lens 7 for condensing laser light reflected from object 1 on area sensor 5, and light receiving unit 11 having mirror 9 It is composed of

As the area sensor 5, for example, a two-dimensional CCD image sensor having a photoelectric conversion element such as a photodiode or a phototransistor is used. As shown in FIG. 2, the light receiving pixels P of the area sensor 5 include a plurality of pixel lines PL in which a plurality of light receiving pixels P are arranged in the scanning direction of light by the scanning unit 3. Each pixel P is formed in a square, and the area sensor 5
The change of the incident light due to the influence of the relative rotation angle between the light and the optical information is reduced.

Next, a signal processing system of the optical information reading apparatus according to the present embodiment will be described. The output from the area sensor 5 in the light receiving means 11 is input to the output improving means 21 and then output from the signal processing means 23 for binarizing the electric signal and the signal processing means 23, similarly to the conventional device shown in FIG. And decoding means 25 for decoding based on the binarized signal.

The decoding means 25 has a bar code decoding part 25a and an OCR character decoding part 25b. The binary signal output from the signal processing means 23 is input to both decoding parts 25a and 25b. The barcode decoding unit 25a determines the narrow bar and the wide bar by measuring the width of the binarized signal, and restores the barcode 1a based on the narrow bar and the wide bar. The OCR character decoding unit 25b restores the OCR character 1b by performing pattern matching between the reference OCR character and the binarized signal. The outputs from the two decoding units 25a and 25b are input to a switching unit 25c.
Is configured to select and output the decoded data.

Each means such as the above-mentioned output improving means 21, signal processing means 23, decoding means 25 and the like is generally constituted by an analog circuit and a digital circuit. In particular, the decoding means 25 is an electronic control unit (E) comprising a microcomputer.
CU) in many cases. Each of these means is mounted on a component board (not shown), and this component board is provided in the optical information reading device or arranged in an external housing.

Next, the details of the output improving means 21 will be described with reference to FIG. The output improving means 21 is provided for the operational amplifier 3
1, analog delay element 33, three resistors 35a, 35
b, 35c and an analog switch 37, and an adder having two or more inputs is constituted by the operational amplifier 31 and the resistors 35a, 35b, 35c.

The output from the area sensor 5 of the light receiving means 11 is input to the operational amplifier 31 via the first addition resistor 35a. The analog delay element 33 delays the input electric signal by one period during which the scanning unit 3 performs optical scanning in the pixel line PL direction (so-called horizontal scanning direction), and includes an ultrasonic glass delay line and a CCD. A delay line can be used, and the output from the operational amplifier 31 is input to the analog delay element 33.

The output of the analog delay element 33 is
The analog switch 3 is connected via the second addition resistor 35b.
7, and is input to the operational amplifier 31. In this way, one input when operating with the adding means is from the area sensor 5 and the other input is input via the analog delay element 33, the second resistor 35b, and the analog switch 37. Become. The output of the operational amplifier 31 is configured to be input to the operational amplifier 31 again via the feedback resistor 35c.

In the bar code reader of the present embodiment configured as described above, the laser light projected from the scanning means 3 scans the object 1 at high speed. And object 1
Is reflected by the mirror 9 to change the angle, and is condensed by the condenser lens 7 before being incident on the area sensor 5.
Then, an electric signal corresponding to the amount of incident light is input to the output improving means 21 by the photoelectric conversion effect of the area sensor 5.

The output improving means 21 is an adder circuit having a gain. The output enhancer 21 has a resistance value R1 of the first addition resistor 35a, a resistance value R2 of the second addition resistor 35b, and a resistance value Rf of the feedback resistor 35c. Is determined. That is, the gain Ga at the input from the area sensor 5 to the operational amplifier 31
Is

[0023]

(Equation 1)

## EQU1 ## On the other hand, the gain Gb at the input to the operational amplifier 31 via the analog delay element 33 is

[0025]

(Equation 2)

## EQU1 ## On the other hand, if the analog switch 37 is closed, the analog delay element 33 is set to 1 as described above.
To delay the signal for the horizontal scanning time, the area sensor 5
And the signal one horizontal scanning time before the output, that is, the output from the area sensor 5 before one pixel line PL is added and output. Therefore, if R1 = R2 = Ri in Equations 1 and 2, and the input voltage from the area sensor 5 is V1 and the input voltage via the analog delay element 33 is V2, the final output from the output improving means 21 is obtained. Typical output voltage Vout is

[0027]

(Equation 3)

## EQU1 ## FIG. 4A shows the area sensor 5.
Pixel line PL direction does not have an angle (so-called skew angle) with respect to the arrangement direction of bar codes 1a (width direction of bar codes 1a), and the nth and (n +)
1) The output V1 of the area sensor 5 for the pixel line PL and the final output Vout from the output enhancing means 21
Is shown.

Since the output V1 corresponding to the pixel line PL adjacent to the area sensor 5 is added to the output improving means 21, if the correlation between the outputs V1 corresponding to the pixel lines PL is large, the area sensor 5 appears to be apparent. Can obtain the same result as the improvement of the sensitivity. FIG. 4 (A)
In this case, since the output V1 (n) and the output V1 (n + 1) are synchronized, the final output Vou from the output improving means 21 is output.
t is almost doubled in level, and an improvement in output is achieved.

On the other hand, FIG. 4B shows the case where the pixel line PL direction of the area sensor 5 has the skew angle θ with respect to the arrangement direction of the barcodes 1a and the adjacent m-th and (m).
The output V1 of the area sensor 5 for the (+1) th pixel line PL and the final output Vou from the output enhancement means 21
t is shown. In this case, the m-th pixel line PL
, And an output V1 (m + 1) corresponding to the (m + 1) th pixel line PL has an output timing shift (τ).

Therefore, both pixel lines PL (m), PL
Although the degree of correlation between (m + 1) is low, in the case shown in FIG. 4B, the output V1 (m) and the output V1 (m + 1)
Is small, the two outputs V1 (m),
V1 (m + 1) is added, and the output level of the output Vout is improved. Therefore, if the skew angle θ is within a certain range, the addition of the output V1 corresponding to the adjacent pixel line PL in the output enhancement unit 21 is performed by the area sensor 5
The same effect as the improvement of the sensitivity is produced.

The output V corresponding to such a pixel line PL
Other output enhancement methods that use the correlation characteristics of read data, such as between one, use inter-field (or frame) correlation. In this case, it is necessary to add the data of one field (or one frame) before adding the data, so that a memory for one field (or one frame) is required and the cost is increased.
However, in the case of the barcode 1a, since a constant pattern is continuous except for both ends, the correlation between the outputs V1 corresponding to the pixel lines PL of the area sensor 5 in the present embodiment becomes relatively large, and It is good to add in between.

The signal subjected to the operation of the output improving means 21 as necessary is converted into a binary signal by the signal processing means 23 and input to the decoding means 25. Next, the process of decoding and outputting the captured binary signal will be described with reference to the flowchart of FIG.

First, the analog switch 37 is opened (step 100, hereinafter simply referred to as S100, the same applies hereinafter), a binary signal is fetched from the signal processing means 23 (S110), and the OCR character decoding section 25b operates. (S120). If the decoding has been normally performed (S130: YES), the received binary signal is
It is an R character, and the switching means 25c is output with the OCR character side (S140). Subsequently, an end determination is made (S15
0), if not completed, return to S100 and repeat the following processing.

On the other hand, if the decoding is not performed normally in S130, the analog switch 37 is closed (S16).
0). Then, as described above, the signal whose output has been improved by the operation of the output improving unit 21 is fetched, the barcode decoding unit 25a is operated (S170), and if the signal is decoded normally (S180: YES), The fetched binary signal is a barcode, and the switching unit 25c is set to the barcode side and output (S190).

As described above, the OCR character 1b is handled as a signal from the normal area sensor 5, and the barcode 1
In the case of “a”, the bar code 1a and the OCR character 1b
The reading performance of the optical information can be improved while the reading of the information is shared by one device.

In the above embodiment, the analog delay element 3
Although only one 3 is provided, it may be added as needed.
For example, FIG. 6 shows a case where a second analog delay element 53 is added. The two analog delay elements 33 and 53 are arranged in parallel, and the second analog delay element 53 inputs to the operational amplifier 31 via the third addition resistor 55 and further via the analog switch 37. In this case, the first analog delay element 33 applies one horizontal scanning time (1H) as in the above embodiment.
, And the second analog delay element 53 is set to delay for two horizontal scanning times (2H).

In this case, since the outputs corresponding to the three pixel lines PL are added by the first and second analog delay elements 33 and 53, the three pixels P (1,1) shown in FIG. ), P (1,2) and P (1,3) in FIG.
Light receiving sensitivity equivalent to that of the pixel S1 of the line sensor shown in FIG. Similarly, three pixels P (2,
With 1), P (2,2), and P (2,3), light receiving sensitivity equivalent to that of the pixel S2 in FIG. 7B can be obtained. Therefore,
Greater light receiving sensitivity can be obtained.

[0039]

As described above, according to the optical information reading apparatus of the present invention, the pixel line during the current scanning of the area sensor is read.
Output corresponding to the previous pixel line.
Since the output is increased and added to the reading means, the light receiving sensitivity equivalent to a line sensor can be obtained even when an area sensor having a small light receiving area per pixel is used. There is an effect that a sufficient reading performance of target information can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a configuration of an entire optical information reading apparatus according to an embodiment.

FIG. 2 is an explanatory diagram of an area sensor.

FIG. 3 is a circuit diagram of an output improving unit.

4A is an output waveform chart when there is no skew angle, and FIG. 4B is an output waveform chart when there is a skew angle.

FIG. 5 is a flowchart showing a decoding process for decoding and outputting a captured binary signal.

FIG. 6 is a circuit diagram of an output improving unit when two delay elements are used.

FIG. 7 is an explanatory diagram for comparing an area sensor and a line sensor when there are two delay elements.

FIG. 8 is a schematic configuration diagram illustrating a configuration of an entire conventional optical information reading apparatus.

FIG. 9 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

P: light receiving pixel, PL: pixel line, 1: target object,
1a: barcode, 1b: OCR character, 5 ...
Area sensor, 11 light receiving means, 21 output improving means, 23 signal processing means, 25 decoding means, 25a barcode decoding unit, 25b ...
OCR character decoding unit, 31 ... operational amplifier, 33
… Analog delay element,

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G06K 9/20 G06K 7/10

Claims (1)

(57) [Claims] 1. A scanning device for projecting and scanning light on an object on which optical information is described, and a two-dimensional area sensor having a plurality of pixel lines in which a plurality of light receiving pixels are arranged in a scanning direction. Optical receiving means for receiving reflected light reflected from an object and outputting an electric signal according to the amount of received light, and reading means for reading the optical information based on the electric signal from the light receiving means In the information reading device, provided in an electric signal path from the light receiving unit to the reading unit
And one line is output to the output corresponding to the pixel line currently being scanned.
Add the output corresponding to the previous pixel line, and
Output improving means for improving the output from the stage to the reading means
And the output improving means includes a circuit for performing optical scanning in the pixel line direction by the scanning means.
Element that delays an electrical signal by a delay amount corresponding to the period
And the electric signal output from the light receiving means to one input
And the other input of the addition means is output from the addition means.
The delayed electrical signal is delayed by the delay element.
The electric signal corresponding to the result of the addition by the adding means is
Output is improved by reading to the reading means
An optical information reading device, comprising: