JPH0916702A - Data symbol reader - Google Patents

Abstract

PURPOSE: To properly read a data symbol, regardless of the size of the data symbol. CONSTITUTION: A data symbol reader 1 is composed of a CCD 43, zoom lens 46, CCD driving circuit 6, amplifier circuit 8, binarizing circuit 9, memory 12, control means 15, LED 41, LED driving circuit 42, zoom driving circuit 10, motor 11, driver 16 for communication, switch circuit 13, switch 14 and display means 18 or the like. In the case of reading, the magnification of the zoom lens 46 is increased from a minimum magnification step by step until a data symbol 38 can be properly read (until proper decode data can be provided).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a data symbol reader for reading coded information such as two-dimensional data symbols.

[0002]

2. Description of the Related Art Today, a method and apparatus for converting product information into a bar code and reading the bar code with a bar code reader are widely used for application to, for example, a POS system. However, the bar code is read one-dimensionally by scanning in the bar arrangement direction, and there is a limit to the amount of information.

Therefore, in recent years, as a device capable of carrying more information, for example, a two-dimensional data symbol in which a black and white mosaic pattern is two-dimensionally arranged and a data symbol reading device for reading the two-dimensional data symbol have been developed. This data symbol reading device is roughly classified into one having a configuration in which an image sensor, for example, an area sensor such as a CCD is used to read a data symbol pattern two-dimensionally at the same time, and a line sensor is used for each line. There is a configuration in which the reading unit and the data symbol are relatively moved in a direction orthogonal to the main scanning direction to perform sub-scanning and two-dimensional reading while scanning.

Among them, the one using the image pickup device (area sensor) is excellent in that it is not necessary to move the reading section and the data symbol relative to each other because of the sub-scanning and the reading can be performed in a short time. It is attracting attention.

However, in the conventional data symbol reading apparatus having a configuration using this image pickup device (area sensor), when reading a relatively small data symbol, the size of the data symbol with respect to the captured image (captured image). Is small, and in particular, the cells forming the data symbol are small, so that the cell cannot be recognized properly, which causes a problem that a reading error of the data symbol occurs.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to read a data symbol by enlarging it so that it can be read regardless of the size of the data symbol, especially the size of the cells forming the data symbol. An object of the present invention is to provide a data symbol reading device that can be properly read.

[0007]

This and other objects are achieved by the present invention which is defined below as (1) to (7).

(1) A data symbol reading device for reading the data symbol by forming an image of the data symbol on the symbol reading area on an image pickup device by an optical system capable of changing the magnification, and changing the magnification of the optical system. The driving unit includes a driving unit that changes the driving unit and a control unit that controls driving of the driving unit. The controlling unit can read the magnification of the optical system when reading the data symbol. A data symbol reading device characterized by controlling to change to a magnification.

(2) A data symbol reading apparatus for reading the data symbol by forming an image of the data symbol on the symbol reading area on an image pickup device by an optical system capable of changing the magnification, and the magnification of the optical system is changed. A driving unit for changing the driving unit and a control unit for controlling the driving of the driving unit, wherein the driving unit controls the magnification of the optical system when reading, and the data symbol is the symbol reading area. The data symbol reading apparatus is characterized by controlling so as to change to a substantially maximum magnification included in.

(3) There is a discriminating means for discriminating whether or not the data symbol is read, and the control means keeps the driving means until the discriminating means discriminates that the data symbol has been properly read. The data symbol reading device according to (1), wherein the magnification of the optical system is controlled so as to be increased from a substantially minimum magnification.

(4) There is a discriminating means for discriminating whether or not the data symbol is read, and the control means keeps the driving means until the discriminating means discriminates that the data symbol has been properly read. The data symbol reading device according to (1) or (2), wherein the magnification of the optical system is controlled so as to be reduced from the maximum magnification.

(5) The data symbol reading device according to any one of the above (1) to (4), which has an illuminating means for illuminating the symbol reading area.

(6) The data symbol reading device according to (5), wherein the illumination means has a function of adjusting the amount of emitted light so that the exposure is properly performed.

(7) The data symbol reader according to any one of (1) to (6), wherein the data symbol is a two-dimensional data symbol.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The data symbol reading apparatus of the present invention will be described below in detail with reference to the preferred embodiments shown in the accompanying drawings. 1 is a perspective view showing a first embodiment of a data symbol reading device of the present invention, FIG. 2 is a sectional side view of the data symbol reading device shown in FIG. 1, and FIG. 3 is a data symbol reading device shown in FIG. Bottom view of the head part in
FIG. 4 is a block diagram showing a circuit configuration of the data symbol reading apparatus shown in FIG.

As shown in these figures, the data symbol reading device 1 of the present invention is composed of a vertically long grip portion 21 to be gripped by hand and an L-shaped head portion 22 formed on the tip side thereof. It has a casing 2, a signal processing circuit 5, a light source drive circuit 42 and a communication driver 16 which will be described later are housed in the grip portion 21, and the light from the symbol reading area 36 is stored in the head portion 22. A reading unit 4 that receives light is stored.

A trigger switch 19 for starting the reading operation by the reading section 4 is provided on one side of the grip section 21, and a display means 18 is provided on the tip-side upper surface of the grip section 21. . In the present embodiment, the display means 18 is composed of an LCD (liquid crystal display element), but not limited to this, it may be a display device such as an LED (light emitting element) or a CRT.

The reading section 4 includes a symbol reading area 3
A pair of LEDs (light emitting diodes) 41 for illuminating 6;
CCD (charge coupled device) 43 which is an image pickup device
An optical system 44 that guides the light (reflected light in this embodiment) from the symbol reading area 36 so as to form an image on the light receiving surface of the CCD 43, and a support member 48 that supports these.

The optical system 44 includes a symbol reading area 36.
It is composed of a mirror 45 that bends an optical path 47 of the reflected light from the optical path 47 in a substantially perpendicular direction, and a zoom lens (lens group) 46 that forms an image of the light reflected by the mirror 45 on the light receiving surface of the CCD 43.

The two LEDs (light sources) 41 are installed substantially symmetrically on the side of the lower end portion of the support member 48 via an optical path 47. A diffuser plate (not shown) having a rough surface may be installed on the light emitting side of the LED 41 in order to make the brightness on the symbol reading area 36 more uniform. This diffuser plate is obtained, for example, by subjecting a part of a transparent plate 7 described later to roughening.

An LED drive circuit (light source drive circuit) 42 for driving the LED 41 is connected to the LED 41. The LED 41 and the LED drive circuit 42 constitute an illumination means.

In the CCD 43, a large number of photodiode pixels are arranged in rows and columns, and a charge corresponding to the amount of light received by each pixel is accumulated, and this charge is sequentially transferred at a predetermined time. . The transferred charges form the image signal of the read image.

The symbol reading area 36 is an area formed on the reading surface (the surface (reference surface) on which the data symbol 38 is located) 37, which is illuminated by the LED 41 and the reflected light is reflected by the CCD 43. Receive light,
This is the area where the data can be read. The symbol reading area 36 varies depending on the magnification (angle of view) of the zoom lens 46, but the symbol reading area 36 at the minimum magnification (maximum angle of view) substantially coincides with the tip opening 31 of the housing 3 described later. Or includes a tip opening 31.

In this embodiment, as shown in FIG. 3, the data symbol (symbol code) 38 has x rows × y columns (x,
Each y is composed of a black or white (or transparent) mosaic (cell) arranged in an integer of 2 or more. The black or white of this mosaic represents, for example, 0 or 1 in a binary system, and desired information is specified by this combination. Needless to say, the data symbol 38 is not limited to the one having the illustrated configuration.

In the reading unit 4 constructed as described above, the LEDs 41 are turned on by the operation of the LED drive circuit 42, and the light emitted from both LEDs 41 is applied to the symbol reading area 36, and the reflected light is reflected by the optical system. An image is formed on the light receiving surface of the CCD 43 via 44, and an image signal (analog signal) corresponding to the received light amount is output.

The head portion 22 of the casing 2 serves to keep the reading portion 4 at a predetermined distance (optical path length) from the symbol reading area 36, that is, the symbol reading area 3
The casing 3 extended from the reading unit 4 to the symbol reading region 36 side as a guide member for defining the distance at which the image of the data symbol 38 placed on the image forming device 6 is formed on the light receiving surface of the CCD 43 by the optical system 44. have. The housing 3 is configured so as to substantially surround the optical path of the illumination light from the LED 41 and the optical path 47 of the reflected light from the symbol reading area 36.
The cross section (transverse cross section) parallel to is rectangular.

The housing 3 has a reading surface 3 at its tip.
The length is set such that the light from the symbol reading area 36 forms an image on the light receiving surface of the CCD 43 by the optical system 44 when it comes into contact with the light receiving surface 7.

A rectangular tip opening 31 is formed at the tip of the housing 3. That is, the front end surface of the housing 3 constitutes an opening. A transparent plate 7 having a dustproof function is provided inside the housing 3 (inside the tip end opening 31) in the optical path 47.
And is installed almost vertically. The transparent plate 7 is located in the vicinity of the lower end of the support member 48, and the internal space of the housing 3 is a space 4 a on the tip opening 31 side and a space 4 on the reading unit 4 side.
It is installed so as to be divided into b and. As the transparent plate 7, those made of various kinds of glass and various kinds of plastics can be used. By providing such a transparent plate 7, foreign matter such as dust, dust, etc., moisture, etc., can be provided in the space 4 on the reading unit 4 side.
Intrusion into b is prevented.

In the data symbol reading apparatus 1, a signal processing circuit 5 for processing an image signal from the reading unit 4 is provided inside the casing 2 on, for example, a printed circuit board. As shown in FIG. 4, the signal processing circuit 5 is mainly composed of a CCD drive circuit 6, an amplification circuit 8, a binarization circuit 9, a memory 12, a control means (CPU) 15 and an electrical connection line thereof. ing. The main function of the discriminating means for discriminating whether the data symbol 38 is read correctly or not is achieved by the control means 15.

The control means 15 includes a zoom drive circuit 10, an LED drive circuit 42, and a communication driver 16
A switch circuit 13 such as a trigger switch 19 and a power switch (main switch), a switch 14,
The display means 18 is connected to each.

A motor (stepping motor) 11 for driving the zoom lens 46 is connected to the zoom drive circuit 10. The zoom drive circuit 10 and the motor 11 drive a zoom drive ring (not shown) that supports and drives the zoom lens 46 from the widest angle position (wide angle end) to the maximum telephoto position (telephoto end) by one unit driving step (1 step).
They can be driven one by one. The zoom drive circuit 10, the motor 11 and the like constitute drive means for changing the magnification of the optical system 44 (zoom lens 46).

The "1 unit driving step" means
The total drive amount of the zoom drive ring from the widest angle position to the maximum telephoto position is equally divided into N (N is an integer of 2 or more) (for example, 20
(Equal division into two) means one unit.

The switch 14 is composed of a normally open type limit switch, and is turned on when its operating piece is pressed. The switch 14 is turned on by pressing the operating piece when the zoom driving ring of the zoom lens 46 is located at the widest angle position, that is, when the magnification of the zoom lens 46 is the minimum magnification. ing. Further, when the zoom drive ring is driven from the widest angle position to the telephoto side, the switch 14 separates from the operating piece and is turned off.

The control means 15 grasps the state of the switch 14 (on / off state), and the switch 14
From the state of and the rotation amount and rotation direction of the motor 11,
The magnification (focal length) of the zoom lens 46 is known.
That is, the control unit 15 recognizes that the magnification of the zoom lens 46 is the minimum magnification when the switch 14 is on, and the number of driving steps of the zoom lens 46 after the switch 14 is off (how many steps have been driven). Thus, the magnification of the zoom lens 46 is recognized. The zoom lens 4
The magnification of 6 is used for decoding, adjusting the amount of light emitted from the LED 41, and determining whether the magnification of the zoom lens 46 is the maximum magnification, which will be described later.

FIG. 5 shows the magnification (angle of view) of the zoom lens 46.
And (A) is a schematic diagram showing the relationship between the symbol reading area and the symbol reading area. FIG. 6A is a diagram showing the symbol reading area 191 when the magnification of the zoom lens 46 is set to the minimum magnification.
(B) shows the symbol reading area 1 when the magnification of the zoom lens 46 is higher than the minimum magnification (high magnification).
It is a figure which shows 92.

When reading a relatively small data symbol 38, as shown in FIG. 5 (A), when the image is picked up at the minimum magnification, the data symbol 38, especially the individual cells forming the data symbol 38, are recorded in the symbol reading area 191. Since the size of the data symbol 38 becomes smaller, the accuracy of reading and decoding the data symbol 38 becomes lower. In such a case, in the data symbol reading device 1, the zoom lens 46 is driven to the telephoto side, the magnification of the zoom lens 46 is increased, and reading is performed.

As shown in FIG. 5B, the zoom lens 4
When 6 is driven to the telephoto side and imaged at a high magnification, the data symbol 38, particularly, the symbol reading area 192,
The individual cells that make it up are enlarged to be large enough to be read, which improves the accuracy of reading and decoding the data symbols 38.

Next, the operation of the data symbol reading device 1 will be described. In this case, first, an outline will be described. In the data symbol reader 1, when the trigger switch 19 is turned on while the power switch is turned on, reading is started. At the time of this reading, variable magnification (zoom driving) is performed by feedback control in which the magnification of the zoom lens 46 is increased by one step from the minimum magnification until the data symbol 38 can be read.

That is, the magnification of the zoom lens 46 is first set to the minimum magnification, that is, the widest angle side, and an image is taken. Then, the signal processing circuit 5 performs predetermined signal processing and decoding as described later, and determines whether or not proper decoded data is obtained (whether or not the data symbol 38 is read). If proper decoded data cannot be obtained, the zoom driving ring of the zoom lens 46 is driven one step in the direction of increasing the magnification (telephoto side), image pickup is performed again, and predetermined signal processing and decoding are performed.
Again, it is determined whether proper decoded data has been obtained. Hereinafter, the above operation is repeated until proper decoded data is obtained (until the data symbol 38 is properly read).

When the proper decoded data is obtained, the decoded data is input by the communication driver 16 to the host computer 17 such as a personal computer or a workstation installed outside.
In such a host computer 17, the input data is stored and tabulated.

The LED drive circuit 42 is a circuit for supplying electric power to the LED 41 and variably lighting the amount of emitted light.
The operation is controlled by the control means 15. When the power switch is turned on, the control means 15 activates the LED drive circuit 42, which causes the LED 41 to light up.

In this case, as described above, the control means 15
Knows the magnification of the zoom lens 46 from the state of the switch 14 and the rotation amount and rotation direction of the motor 11, and according to the magnification, the LED is set so that the exposure is properly performed.
The drive circuit 42 is controlled to adjust the amount of light emitted from the LED 41. The lighting time of the LED 41 is the same as the LED driving circuit 4
2 or set by the control means 15 as desired.

When the power switch is turned on, the control means 15 operates the CCD drive circuit 6. A CCD horizontal drive pulse and a CCD vertical drive pulse are output from the CCD drive circuit 6 to the CCD 43, and charge accumulation and transfer in the CCD 43 are controlled.

Further, the CCD drive circuit 6 generates a clock signal and sends a signal (composite clock signal) obtained by combining this signal with a horizontal synchronizing signal and a vertical synchronizing signal to the control means 15.

The image signal (analog signal) sequentially output from the CCD 43 of the reading section 4 is amplified by the amplifier circuit 8, converted into a digital image signal by an A / D converter (not shown), and input to the binarization circuit 9. To be done.

In the binarizing circuit 9, the digital image signal is compared with the threshold data and binarized. Binarization circuit 9
The binarized data output by the above is stored in a predetermined address of the memory 12 by an address counter incorporated in the control means 15. The address counter is driven by the composite clock signal input from the CCD drive circuit 6.

Data is sequentially read from the memory 12 in accordance with the address designated by the address counter (the reading order may be reverse to the one stored in the memory 12), and one screen worth of data is read. , Control means 15
In the calculation unit of, for example, necessary image processing such as image inversion, contour detection (extraction of information about the data symbol 38), dropout correction, rotation, etc. is performed, and further, by a decoder built in the control means 15. , And the data symbol 38 is decoded into data according to the system. The decoded data (decoded data) is output to the host computer 17 via the communication driver 16.

Next, the control operation of the control means 15 of the data symbol reading device 1 will be described. FIG. 6 is a flowchart showing the operation of the control means 15 of the data symbol reading device 1. Hereinafter, description will be made based on this flowchart.

The zoom drive circuit 10 drives the zoom lens 46 to the wide-angle end to set the zoom lens 46 to the minimum magnification (the angle of view is the maximum angle of view) (step 101). Next, an image is captured (step 102). In this step 102, an image is picked up by the CCD 43, the image data (image signal) from the CCD 43 is binarized, and this binarized data (binarized signal) is written in the memory 12.

Next, the symbol is cut out (step 103). That is, the binarized data is read from the memory 12, and the contour of the data symbol 38 to be decoded is detected based on the binarized data (data symbol 3
8) is extracted).

The data symbol 38 has a black outer periphery on four sides so that its contour can be discriminated, and binarized data corresponding to the outermost black pixel of the data symbol 38 is traced and extracted. The contour of the data symbol 38 is detected, and the area surrounded by the black pixels forming the contour of the data symbol 38 is recognized as the decoding area.

Next, it is judged whether or not the symbol cutting is OK (step 104). In step 104, as a result of tracking the binarized data corresponding to the outermost black pixel of the data symbol 38, if it is possible to make one round from the starting point and return to the starting point (the outline of the data symbol 38 is If it can be detected), the symbol cutout O
If it is determined to be K, and the tracking is interrupted halfway or if the tracking cannot be started (if the contour of the data symbol 38 cannot be detected), it is determined to be a symbol cutout error (NG). To do.

For example, when an image is taken with the data symbol 38 included in the symbol reading area 36,
When it is determined that the symbol cutting is OK, the image is taken in a state in which the data symbol 38 protrudes from the symbol reading area 36 and a state in which the data symbol 38 does not exist in the symbol reading area 36 (for example, the zoom lens 46).
Is too large), it is judged as a symbol cutout error.

If it is determined in step 104 that a symbol cutout error has occurred, a predetermined error process is performed. In the error processing, for example, the display unit 18 displays a warning indicating that decoding is impossible.

When it is determined in step 104 that the symbol cutout is OK, the above-described predetermined image processing is performed on the cutout binarized data in the decoded area to decode (the data symbol 38 represents. Information is decrypted) (step 105).

Then, it is judged whether the reading is OK (decoding OK) (step 106). In step 106, when the data symbol 38 is properly read, that is, when proper decoded data is obtained, it is determined that the reading is OK. Also, data symbol 3
When the reading of No. 8 is not properly performed, that is, when the proper decoded data cannot be obtained, it is determined as a reading error (NG).

For example, when the magnification of the zoom lens 46 is too small to properly recognize the cells forming the data symbol 38, proper decoded data cannot be obtained and it is determined that a read error has occurred.

When it is determined in step 106 that the reading is OK (decoding OK), the decoded data is transmitted (transmitted) to the host computer 17 via the communication driver 16 (step 109).

If it is determined in step 106 that there is a reading error, it is determined whether the magnification of the zoom lens 46 is the maximum magnification (maximum telephoto) (step 10).
7). When it is determined in step 107 that the magnification of the zoom lens 46 is the maximum magnification, predetermined error processing is performed.

If it is determined in step 107 that the magnification of the zoom lens 46 is not the maximum magnification,
The zoom drive circuit 10 drives the zoom lens 46 toward the high magnification side (telephoto side) by one step (step 108),
After this, the process returns to step 102, and step 102 is performed again.
Execute the following.

In step 108, the zoom lens 46
If the cells forming the data symbol 38 can be properly recognized at a predetermined magnification, the data symbol 38 can be properly read, that is, the data can be read properly. Decoded data is obtained, and it is determined in step 106 that the reading is OK. Then, after this, step 109 is executed.

After step 109, the zoom drive circuit 10
Thus, the zoom lens 46 is driven to the wide-angle end, and the magnification of the zoom lens 46 is set to the minimum magnification (step 110).
This is the end of this program.

As described above, according to the data symbol reading apparatus 1 of the present embodiment, the zoom lens 4 is read at the time of reading.
6 is driven and the magnification is changed to a magnification (minimum magnification) at which the data symbol 38 can be properly read. Therefore, the size of the data symbol 38, in particular, the size of the cells forming the data symbol 38. Regardless of this, it is possible to prevent the reading error of the data symbol 38 and improve the reading accuracy of the data symbol 38.

Further, in the data symbol reading device 1, since the magnification of the zoom lens 46 is automatically changed to a magnification that allows the data symbol 38 to be properly read, the magnification of the optical system is manually changed. Compared to the data symbol reader, the operation is simplified and
The data symbol 38 can be read properly and reliably. In the data symbol reading device 1, it is preferable that there is no image noise other than the data symbol 38 in the captured image (inside the captured image).

Next, a second embodiment of the data symbol reading apparatus of the present invention will be described. The description of common points with the above-described data symbol reading device 1 will be omitted, and the differences will be described. FIG. 7 is a block diagram showing the circuit configuration of the second embodiment of the data symbol reading apparatus of the present invention.

As shown in the figure, the data symbol reading device 1a has a switch 14a. The switch 14a is composed of a normally open type limit switch,
It is turned on when the operating piece is pressed. This switch 14a is used when the zoom driving ring of the zoom lens 46 is located at the most telephoto position, that is, the zoom lens 4
When the magnification of 6 is the maximum magnification, the operating piece is pressed and turned on. Also, the switch 14a
When the zoom drive ring is driven from the most telephoto position to the wide-angle side, the zoom drive ring separates from the operating piece and turns off.

The control means 15 grasps the state of the switch 14a (whether it is ON or OFF), and the switch 1
The magnification (focal length) of the zoom lens 46 is known from the state of 4a and the rotation amount and rotation direction of the motor 11. That is, the control unit 15 recognizes that the magnification of the zoom lens 46 is the maximum magnification when the switch 14a is on, and the zoom lens 4 after the switch 14a is off.
Depending on the number of driving steps of 6 (how many steps were driven),
The magnification of the zoom lens 46 is recognized. The magnification of the zoom lens 46 is used for decoding, adjusting the amount of light emitted from the LED 41, and determining whether or not the magnification of the zoom lens 46 is the minimum magnification.

Next, the operation of the data symbol reading device 1a will be described. In this case, first, an outline will be described. In the data symbol reader 1a, when the power switch is turned on and the trigger switch 19 is turned on, reading is started. During this reading, the zoom lens 46 is operated until the data symbol 38 can be read (until the magnification of the zoom lens 46 reaches almost the maximum magnification in which the data symbol 38 is included in the symbol reading area 36). The variable magnification (zoom drive) is performed by the feedback control in which the magnification of is decreased by one step from the maximum magnification.

That is, the magnification of the zoom lens 46 is first set to the maximum magnification, that is, the most telephoto side, and an image is picked up. Then, the signal processing circuit 5 performs predetermined signal processing and decoding as described later, and determines whether or not proper decoded data is obtained (whether or not the data symbol 38 is read). If proper decoded data cannot be obtained, the zoom drive ring of the zoom lens 46 is driven one step in the direction of decreasing the magnification (wide-angle side), image pickup is performed again, and predetermined signal processing and decoding are performed.
Again, it is determined whether proper decoded data has been obtained. Hereinafter, the above operation is repeated until proper decoded data is obtained (until the data symbol 38 is properly read).

When proper decode data is obtained, the decode data is input by the communication driver 16 to the host computer 17 such as a personal computer or a workstation installed outside.
In such a host computer 17, the input data is stored and tabulated.

Next, the control operation of the control means 15 of the data symbol reading device 1a will be described. FIG. 8 is a flowchart showing the operation of the control means 15 of the data symbol reading device 1a. Hereinafter, description will be made based on this flowchart.

The zoom drive circuit 10 drives the zoom lens 46 to the telephoto end to maximize the magnification of the zoom lens 46 (the angle of view is the minimum angle of view) (step 201). Next, an image is captured (step 202). In step 202, the CCD 43 captures an image, the image data (image signal) from the CCD 43 is binarized, and the binarized data (binarized signal) is written in the memory 12.

Next, the symbol is cut out (step 203). That is, the binarized data is read from the memory 12, and the contour of the data symbol 38 to be decoded is detected based on the binarized data (data symbol 3
8) is extracted).

Next, 2 in the cut out decoding area
Decoding by performing the above-described predetermined image processing or the like on the binarized data (decoding of information represented by the data symbol 38)
Is performed (step 204).

Then, it is judged whether or not the reading is OK (decoding OK) (step 205). In step 205, when the reading of the data symbol 38 is properly performed, that is, when the proper decoded data is obtained, it is determined that the reading is OK. Also, data symbol 3
When the reading of No. 8 is not properly performed, that is, when the proper decoded data cannot be obtained, it is determined as a reading error (NG). The causes of the reading error here are as follows.

First, for example, when the magnification of the zoom lens 46 is too large to detect the contour of the data symbol 38, that is, when the symbol cutout cannot be performed (data from the symbol reading area 36 is extracted). (When the symbol 38 protrudes or when there is no data symbol 38 in the symbol reading area 36)
At this time, proper decoded data cannot be obtained, and it is determined in step 205 that there is a reading error.

Secondly, even if the data symbol 38 can be cut out, the magnification of the zoom lens 46 is too small to properly recognize the cells forming the data symbol 38. At this time, Since proper decoded data cannot be obtained, it is determined in step 205 that there is a read error.

When it is determined in step 205 that the reading is OK (decoding is OK), the decoded data is transmitted (transmitted) to the host computer 17 via the communication driver 16 (step 208).

If it is determined in step 205 that there is a reading error, it is determined whether the magnification of the zoom lens 46 is the minimum magnification (widest angle) (step 20).
6). If it is determined in step 206 that the magnification of the zoom lens 46 is the minimum magnification, predetermined error processing is performed. In the error processing, for example, the display unit 18 displays a warning indicating that decoding is impossible.

If it is determined in step 107 that the magnification of the zoom lens 46 is not the minimum magnification,
The zoom drive circuit 10 drives the zoom lens 46 toward the low magnification side (wide angle side) by one step (step 207),
After this, the process returns to step 202, and step 202 is performed again.
Execute the following.

When the magnification of the zoom lens 46 is too large to detect the contour of the data symbol 38 and it is determined in step 205 that there is a reading error, the magnification of the zoom lens 46 is increased step by step in step 207. As the number decreases, the contour of the data symbol 38 can be detected at a predetermined magnification. That is, the magnification of the zoom lens 46 is
The data symbol 38 is changed to almost the maximum magnification included in the symbol reading area 36. At this magnification, if the cells forming the data symbol 38 can be properly recognized, the data symbol 38 is properly read, that is, the proper decoded data is obtained, and the reading is OK in step 205. To be judged. Then, after that, the step 208 is executed.

After step 208, the zoom drive circuit 10
Thus, the zoom lens 46 is driven to the telephoto end and the magnification of the zoom lens 46 is set to the maximum magnification (step 209).
This is the end of this program.

As described above, also in the data symbol reading apparatus 1a of the second embodiment, the size of the data symbol 38, in particular, the data symbol 38 is formed, similarly to the data symbol reading apparatus 1 of the first embodiment described above. It is possible to prevent a reading error of the data symbol 38 and improve the reading accuracy of the data symbol 38 irrespective of the size of the cell.

Further, according to the data symbol reading apparatus 1a, the magnification of the zoom lens 46 is set to the data symbol 3
8 is changed to almost the maximum magnification included in the symbol reading area 36 for reading, so that the data symbol 3
The reading accuracy of 8 is further improved.

The data symbol reading apparatus of the present invention has been described above based on the illustrated embodiments, but the present invention is not limited to these. For example, in each of the above embodiments, the light source is the LED 41, but the light source in the present invention is not limited to this, and may be, for example, a halogen lamp or the like.

It is also possible to form one or more openings or transparent windows on the side surface of the housing 3 so that the position of the data symbol 38 can be visually confirmed through the openings or windows. By doing this, when reading,
Positioning for putting the data symbol 38 into the symbol reading area 36 can be performed easily and reliably.

In particular, if the data symbol 38 is arranged in the center of the symbol reading area 36, the data symbol 38 can be enlarged more greatly, so that the reading accuracy of the data symbol 38 is further improved.

Further, the reading section 4 may be constructed so as to illuminate the symbol reading area 36 by taking in external light (natural light). In this case, it has no light source, or
The light source may be configured to illuminate so as to supplement the shortage of external light.

[0089]

As described above, according to the data symbol reading apparatus of the present invention, the magnification (angle of view) of the optical system can be changed by the driving means. For example, when reading, the magnification of the optical system can be changed. Is changed to a magnification at which the data symbol can be read (a magnification at which the data symbol can be properly read). Therefore, the data symbol can be read regardless of the size of the data symbol, particularly the size of the cells forming the data symbol. It is possible to prevent an error and improve the reading accuracy of the data symbol.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of a data symbol reading device of the present invention.

FIG. 2 is a sectional side view of the data symbol reading device shown in FIG.

FIG. 3 is a bottom view of a head unit in the data symbol reading device shown in FIG.

4 is a block diagram showing a circuit configuration of the data symbol reading device shown in FIG. 1. FIG.

FIG. 5 is a magnification (angle of view) of the zoom lens according to the present invention.
FIG. 3 is a schematic diagram showing the relationship between the symbol reading area and the symbol reading area.

6 is a flowchart showing the operation of the control means of the data symbol reading apparatus shown in FIG.

FIG. 7 is a block diagram showing a circuit configuration in a second embodiment of the data symbol reading apparatus of the present invention.

8 is a flowchart showing the operation of the control means of the data symbol reading device shown in FIG. 7. FIG.

[Explanation of symbols]

 1, 1a Data symbol reading device 2 Casing 21 Gripping portion 22 Head portion 3 Housing 31 Tip opening 36 Symbol reading area 37 Reading surface 38 Data symbol 4 Reading portions 4a, 4b Space 41 LED 42 LED drive circuit 43 CCD 44 Optical system 45 Mirror 46 Zoom lens 47 Optical path 48 Support member 5 Signal processing circuit 6 CCD drive circuit 7 Transparent plate 8 Amplification circuit 9 Binarization circuit 10 Zoom drive circuit 11 Motor 12 Memory 13 Switch circuit 14, 14a switch 15 Control means (CPU) 16 Communication driver 17 Host computer 18 Display means 19 Trigger switch 191, 192 Symbol reading area 193, 194 Side 101-110 step 201-209 step

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Makoto Nakai 2-36-9 Maenocho, Itabashi-ku, Tokyo Asahi Kogaku Kogyo Co., Ltd. (72) Inventor Nobuhiro Ishizuka 2-36- Maenocho, Itabashi-ku, Tokyo No. 9 Asahi Kogaku Industry Co., Ltd.

Claims (7)

[Claims] 1. A data symbol reading device for forming an image of a data symbol on a symbol reading area on an image sensor by an optical system capable of changing the magnification and reading the data symbol, wherein the magnification of the optical system is changed. A driving unit for controlling the driving of the driving unit, and the driving unit controls the magnification of the optical system to read the data symbol at the time of reading by the driving unit. A data symbol reading device characterized by controlling to change to. 2. A data symbol reading device for forming an image of a data symbol on a symbol reading area on an image sensor by an optical system capable of changing the magnification and reading the data symbol, wherein the magnification of the optical system is changed. Drive means for controlling, and control means for controlling the drive of the drive means, wherein the drive means, when the reading means, the magnification of the optical system, the data symbol in the symbol reading area A data symbol reading device characterized by controlling to change to a substantially maximum magnification included. 3. The driving means includes the discriminating means for discriminating whether or not the data symbol has been read, and the control means keeps the driving means until the discriminating means discriminates that the data symbol has been properly read. The data symbol reading device according to claim 1, wherein the magnification of the optical system is controlled so as to be increased from a substantially minimum magnification. 4. A discriminating means for discriminating whether the data symbol is read or not is provided, and the control means is arranged so that the drive means is operable until the discriminating means discriminates that the data symbol has been properly read. 3. The data symbol reader according to claim 1, wherein the magnification of the optical system is controlled so as to be reduced from the maximum magnification. 5. The data symbol reading device according to claim 1, further comprising an illumination unit that illuminates the symbol reading area. 6. The data symbol reading device according to claim 5, wherein the illumination unit has a function of adjusting the amount of emitted light so that the exposure is properly performed. 7. The data symbol reading device according to claim 1, wherein the data symbol is a two-dimensional data symbol.