JPH02136984A - Laser scanner - Google Patents

Abstract

PURPOSE:To improve the read rate of a bar code by decoding the bar code correctly and thus controlling an automatic focusing mechanism. CONSTITUTION:When a decoding part 11 decodes the bar code correctly, the decoding part 11 sends a signal indicating that the decoding is performed correctly to a control circuit 11. The control circuit 1 when receiving the signal from the decoding part 11 stops the driving by a driving signal generating circuit 6 while stopping the emission of a laser beam and the scanning of a reflecting mirror 18 by a galvano-scanner 19, thereby stopping the focus adjusting operation of a focus adjusting lens 14. Thus, the bar code is decoded correctly to control the automatic focusing mechanism, so the read rate of the bar code is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laser scanner, and particularly to a laser scanner for optically reading barcodes displayed on paper or other media.

[Conventional technology]

Barcode scanners that use a method of reading barcodes by scanning a laser beam are now equipped with an autofocus mechanism that allows the focus of the optical system to be varied in order to expand the reading range and improve operability. This makes it possible to obtain a wider reading range than with a fixed focal point.

FIG. 8 is an explanatory diagram of barcode reading by a laser scanner, where 801 is the laser scanner and 802 is a barcode display.

In the figure, reading is performed by placing a laser scanner 801 facing a barcode display 802. At this time, if the optical system of the laser scanner 801 has a fixed focus, the distance between the laser scanner and the barcode display 802, or The reading distance must be such that the barcode display 802 is located within the range of the focal depth of the optical system (lens) of the laser scanner 801, that is, the reading depth d.

FIG. 9 is a resolution explanatory diagram of a laser scanner, in which a laser scanner 801 has a semiconductor laser 8012 in its scanner case 8011 and an optical system (objective lens) 801 for focusing the laser beam from the semiconductor laser.
It has 3.

A laser beam emitted from a semiconductor laser 8012 is focused on a focal point F by an optical system 8013. This focus F
The vicinity of is a high-resolution region H, and as the distance from the focal point F increases, the region becomes a high-resolution region M and a low-resolution region.

The spot diameter of the laser beam at the focal point F is the minimum, and the spot diameter increases as the distance from the focal point F increases.

FIG. 10 is an explanatory diagram of the beam spot diameter and read signal waveform at the barcode display position, in which (a) is a barcode display state diagram, (b) is a read signal waveform diagram at the proper spot, and (c ) is the reading waveform diagram at a small diameter spot,
(d) is a read waveform diagram at a large diameter spot.

In the figure, a barcode generally consists of a combination of bars (black background) and spaces (white background), and here, a barcode consisting of wide bars/narrow bars and wide spaces/narrow spaces will be explained as an example.

As shown in FIG. 5A, voids B and chips C may occur in the barcode depending on the printing and the condition of the mezzo layer surface. This barcode is scanned by a laser beam.
When scanning is performed at the position shown in (b), there is a spot diameter of an appropriate size that allows the read waveform to be read correctly without being affected by the void B or chipping C.

On the other hand, when scanning with a small diameter spot that is affected by the size of voids and chips, false waveforms due to void B (a) and waveform shifts due to chipping C (b) are generated, as shown in (C). This will result in inaccurate readings.

Furthermore, when the spot diameter exceeds a certain level, the read waveform becomes dull as a whole as shown in (d), and cannot be decoded.

Scanners with conventional autofocus mechanisms
The optical system is automatically adjusted so that the focal point F shown in the figure is located on the barcode display surface.

Note that this type of laser scanner is well known, so no particular literature will be cited. In addition, as for literature regarding barcodes, 1984.7.1, published by CQ Publishing, "Transistor Technology, Separate Volume, Sensor Interfacing, No.
,4. J p l 179-199. Detailed information is provided in ``Fabrication of Barcode Systems''.

[Problem to be solved by the invention]

The autofocus mechanism in the above conventional technology measures the distance between the scanner and the media regardless of the quality of the barcode media, such as the printing condition or the media surface condition.
It is configured to obtain the minimum beam spot diameter on the media.

Therefore, depending on the quality of the barcode, there is a problem in that it may not be possible to read the barcode because the beam spot diameter is small.

The purpose of the present invention is to solve the problems of the prior art,
An object of the present invention is to provide a laser scanner that has a significantly improved barcode reading rate.

[Means to solve the problem]

The problem with the prior art described above is that in reading barcodes, simply having a small beam spot diameter and high resolution is not the optimum condition for reading.

In order to avoid such inconveniences, it is necessary to have a reading beam spot diameter that is large enough to match the quality of the barcode.

The optimal beam spot diameter is determined based on the spot diameter that allows the barcode to be correctly decoded.

The present invention provides means for changing the beam spot diameter by slightly changing the focal position by slightly changing the position of the optical system in order to automatically obtain the above-mentioned optimum beam spot diameter, and the beam spot diameter. means for decoding the barcode by scanning with a laser beam every time the barcode changes; and means for stopping the movement of the optical system when the decoding operation is correctly performed, determining that the beam spot diameter is the optimum beam spot diameter. shall be.

[Effect]

In order to control the autofocus mechanism depending on whether the barcode is correctly decoded,
Barcodes are read with optimal focus according to the surface condition of the media and media, significantly improving the reading rate.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram for explaining one embodiment of the present invention, in which 1 is a control circuit, 2 is a photoelectric conversion unit drive circuit, and 3 is a schematic configuration diagram for explaining an embodiment of the present invention.
is a light emitting element driver, 4 is a drive signal generation circuit for a deflection device, 5 is a deflection device drive circuit, 6 is a drive signal generation circuit for a focus adjustment device (voice coil motor), 7 is a focus adjustment device drive circuit, 8 is a preamplifier, 9 is an amplifier circuit, 10 is a binarization circuit, 11 is a decoding section, 12 is a laser light emitting element, 1
3 is a focus adjustment device, 14 is a focus adjustment lens, 15 is a mirror with a hole, 16 is a light receiving element, 17 is a fixed lens, 18 is a reflection mirror, 19 is a galvano scanner, 20 is a barcode display surface, 21a and 21b are each Switch SWI.

3w2.22 is an output terminal to the host computer. Note that the light emitting element driver 3 and the laser light emitting element 121
, the light receiving element 16 and the preamplifier 8 constitute a photoelectric conversion section 23. In addition, a reflecting mirror 18 and a galvano scanner 1
9 constitute a deflection device.

In the figure, a laser beam from a laser light emitting element 12 is driven by a photoelectric converter driving circuit 2 and energized by a light emitting element driver 3, and is focused by a fixed lens 17 through a hole in a perforated mirror 15. The path is deflected and reaches the barcode display surface 20.

The reflecting mirror 18 deflects and scans the laser beam in one-dimensional direction by the deflection operation of the galvano scanner 19, scans the barcode, and sends the reflected light to the reflecting mirror 18. The light is projected onto the light receiving element 16 via the fixed lens 17.

The galvano scanner (2) 9 is driven by a drive signal from the deflection device drive circuit 5 based on a signal from the drive signal generation circuit 4.

The reflected light from the barcode received by the light receiving element 16 is
The signal is output from the photoelectric conversion section 23 to the amplifier circuit 9 through the preamplifier 8, and after being amplified to a predetermined level in the amplifier circuit 9, it is provided to the binarization circuit 10.

The binarization circuit 10 binarizes the input signal, supplies it to the decoding unit 11, and outputs the decoded signal (decoded data).
is transmitted from terminal 22 to a host computer (not shown).

By the way, the laser light emitting element 12 and the barcode display surface 2
Since the distance between 0 and 0 is not fixed, if the scanner optical system has a fixed focus, the focus position must be adjusted by moving the scanner or the barcode medium.

In the figure, the focus adjustment is automatically performed. A so-called voice coil motor 13 is attached to the focus adjustment lens 14, and the focus adjustment lens 14 is used to change the distance between the laser light emitting element 12 and the barcode display surface 209. The optical system is moved back and forth in the optical axis direction according to the direction of the optical system.

This movement of the focus adjustment lens 14 is performed by the focus adjustment device drive circuit 7 applying a drive current to the voice coil motor 13 in response to a drive signal generated by a drive signal generation circuit 6 based on a control signal from the control circuit 1. .

In addition, as for the deflection device, the galvano scanner 19 is connected to the reflection mirror 1.
8 is a device that swings a laser beam in a one-dimensional direction through a laser light emitting element 12 (7) in the direction of scanning the barcode on the barcode display surface 20, and the drive signal generation circuit 4
It is driven by a deflection device drive circuit 5 which inputs a drive signal.

Switches 3wl and Sw2 are two-stage switches operated by the operator, and when the first stage is operated, switch Sw1 (21a) is activated.
turns on and supplies a drive signal to the light emitting element driver 2 to cause the laser light emitting element 13 to emit a laser beam, and the drive signal generating circuit 4. The deflection device drive circuit 5 is driven to vibrate the reflection mirror 18 using the galvano scanner 19 to scan the barcode display surface 20 with the laser beam.

Next, in the second step, the switch 5w2 (21b) is also turned on, and the drive signal generation circuit 6. Focus adjustment device drive circuit 7
Focus adjustment lens 14 with voice coil motor 13 via
to adjust the focus.

The drive signal generation circuit 6 sequentially generates a continuous drive signal or a stepwise drive signal 1, for example, a 10-level drive signal, and the focus adjustment device drive circuit 7 drives the voice coil motor 13 using this drive signal. Then, the focusing lens 14 is moved back and forth along the optical axis continuously or stepwise.

In the process of moving the focusing lens 14, the barcode on the barcode display surface 20 is irradiated with a laser beam,
The reflected light passes through the reflecting mirror 18° fixed lens 17. The light is focused on a light receiving element 16 via a perforated mirror 15 and converted into an electrical signal.

The converted electrical signal is pre-amplified by a preamplifier 8, amplified to a predetermined level by an amplifier circuit 9, and input to a binarization circuit 10.

The binarization circuit 10 binarizes the human input signal, supplies it to the decoding section 11 for decoding, and, when correctly decoded, transmits the decoded data signal from the terminal 22 to the host computer.

When the barcode is correctly decoded by the decoding section 11, the decoding section 11 provides the control circuit 1 with a signal indicating that the decoding has been correctly decoded.

When the control circuit 1 receives the signal from the decoding section 11, the control circuit 1 sends the signal to the light emitting element driver 3 via the photoelectric conversion section driving circuit 2.
Also, the operation of the drive signal generation circuit 4 is stopped, and the emission of the laser beam and the scanning of the reflecting mirror 18 by the galvano scanner 19 are stopped.

At the same time, the control circuit 1 also stops driving the drive signal generation circuit 6 and causes the voice coil motor 13 to stop the focus adjustment lens 14.
focus adjustment operation.

Various methods can be considered for the automatic focus adjustment described above.

Various operating methods will be explained below.

FIG. 2 is a configuration diagram illustrating an example of an operation method configured to continuously move a focusing lens, and shows 11
1 is a decoding circuit, and 112 is an output circuit, which constitutes the decoding section in FIG. Further, 201 is an off signal generation circuit for creating a stop signal (off signal) that stops the reading operation when a predetermined barcode scan is performed.
202 is a counter circuit, 203 is a constant memory, and 204 is a comparator.

In the configuration shown in the figure, the deflection device repeatedly changes the focus of the focusing lens 14 from a position close to the lens to a position far from the lens a predetermined number of times, and the optimal focal position is in the middle. Correct decoding will occur at the focal position.

When decoding is performed, an operation stop signal is output from the output circuit, stopping the entire operation.

The configuration shown in FIG. 2 will be explained in detail below.

A signal S1 is sent from the control circuit 1 to the drive signal generation circuit 4 in FIG.
, the deflection device drive circuit 5 sends the signal bi to the deflection device (
18, 19).

The deflection device (18, 19) continues to drive the reflecting mirror 18 with the galvano scanner 19 while the signal bi is input. The deflection device (18, 19) outputs a signal eg every time one deflection is completed.
Output.

The deflection device drive circuit 5 receives the signal bi by inputting the off signal.
stop the occurrence of

After receiving the signal S2 from the control circuit 1, the photoelectric converter driving circuit 2 outputs the signal Oe to the photoelectric converter 23 upon receiving the signal eg from the deflection device.

The output of the signal Oe is stopped by inputting the off signal.

The photoelectric conversion section 23 energizes the laser emitting element by inputting the signal oe, and applies the output of the light receiving element 16 to the amplifier 9 as a signal es.

The focus adjustment device drive circuit 7 is driven by the drive signal generation circuit 6 which inputs the signal S3 from the control circuit 1, and gives a signal fc to the focus adjustment device (voice coil motor 13), and continuously moves the focus adjustment lens 14. let

The focus adjustment device drive circuit 7 receives the signal f when the off signal is input.
c.

The output signal es of the photoelectric conversion unit 23 is amplified by the amplifier circuit 9, and then converted into a binary level signal by the binarization circuit 10. The converted signal di is decoded by the decoding circuit 111 of the decoding unit 11, and the decoded signal dc is Terminal 2 via output circuit 112
2 to the host computer.

At the same time, the output circuit 112 outputs an off signal to stop the operation of the device.

The off signal generation circuit 201 is composed of a counter circuit 202, a constant memory 203, and a comparator 204. The counter circuit 202 counts the signal eg from the deflection device (18, 19) and sends the count output cn to the comparator 204. give. Further, the count contents are cleared by the input signal of the deflection device drive circuit 5 based on the output of the drive signal generation circuit 4, that is, the input of the drive start signal s1 of the deflection device.

A constant value (total number of scans) is set in the constant memory 203, and the signal cs of this set value and the counter circuit 2
A comparator 204 compares the output signal cn of 02.

The comparator 204 outputs an off signal o when the signal Cn≧signal csO
Output ff.

This off signal is applied to the deflection device drive circuit 5. Photoelectric conversion unit drive circuit 2. The signal is applied to the focus adjustment device drive circuit 7 to stop the operation of the device.

As mentioned above, the device is deactivated when the bar code is correctly decoded or a predetermined number of scans have been performed.

Note that the signals sl, s2 . Although s3 is shown as a separate signal, these may be the same signal.

FIG. 3 is a configuration diagram illustrating the other side of the operation method configured to continuously move the focusing lens, and 11
1 is a decoding circuit, and 112 is an output circuit, which constitutes the decoding section in FIG. Further, 201 is an off signal generation circuit for creating a stop signal (off signal) that stops the reading operation when a predetermined barcode scan is performed.
202 is a counter circuit, 203 is a constant number, 204
are comparators, which are the same as in FIG. 2 above.

The configuration shown in the figure is similar to the one in Figure 2, in which the deflection device repeatedly changes the focus of the focusing lens 14 from a position close to the lens to a position far from the lens a predetermined number of times, thereby achieving the optimum. The focus position is in between, and correct decoding will occur at the optimal focus position.

When decoding is performed or a predetermined number of scans set in constant memory 203 are completed, an operation stop signal is output from the output circuit or off signal generation circuit 201 to stop the entire operation.

The difference between the configuration in Figure 3 and the configuration in Figure 2 is that the deflection device (
18, 19) provides the signal eg output for each deflection to the decoding circuit ill, and uses it as a decoding start signal.

The operation of the other components is the same as that shown in FIG. 2 above.

In addition, in FIGS. 2 and 3 described above, instead of providing an off signal generation circuit, an off signal may be applied from outside the device.

Next, each time the deflection device scans a predetermined number of times, the focusing lens
An example of a configuration in which the drive unit 3 is driven will be described.

FIG. 4 is a block diagram showing an example of an operation system in which the focus adjustment lens is driven every predetermined scan of the deflection device, in which 401 is an OR circuit, 402 is a switch, 403
is the second counter circuit, 404 is the second constant memory, 405
is a second comparator, 201 is an off signal generation circuit, and 202
is the first counter circuit, 203 is the first constant memory, 204
is the first comparator, which includes the counter circuits shown in FIGS. 2 and 3,
They are the same as constant memory and comparator.

Note that the same reference numerals as in FIGS. 2 and 3 correspond to the same parts.

In this figure, since the basic operation of this embodiment is the same as that in FIGS. 2 and 3, the explanation thereof will be omitted, and the characteristic points will be explained.

First, the off signal generation circuit 201 starts with the first counter 202.
．． First constant memory 203. The off signal is generated by the first counter 204 in the same manner as in the previous embodiment.

The switch 402 receives the signal e from the deflection device (18, 19).
At the input of g, the signal eS from the photoelectric converter 23 is applied to the binarization circuit 10 via the amplifier 9 and converted into a binary level.

When the signal fc from the focus adjustment device drive circuit 7 is input, the supply of the signal es from the photoelectric conversion section 23 to the amplifier circuit 9 is stopped.

Note that the drive signal for the focus adjustment device drive circuit 7 uses the signal Cp from the second comparator 405, as will be described later.

The above-mentioned signal fc is for stopping the supply of the signal es to the amplifier circuit 9, that is, stopping the decoding operation, while the focus adjustment device is operating.

The OR circuit 401 takes the logical sum of the signal from the drive signal generation circuit 4 (the signal based on the signal s1 supplied from the control circuit 1) and the output signal Cp of the second comparator 405, which will be described later.
The result is given as a signal p to the second counter circuit 403 as a clear signal.

The second counter circuit 403 counts the signal eg generated each time the deflection is output from the deflection device (1819), and supplies the result to the second comparator 405 as a signal cn2.

The second constant memory 404 is set to a predetermined value (for example, 5), and provides the value C52 to the second comparator 405.

The second comparator 405 outputs the output signal Cn of the second counter 403.
2 is compared with the setting signal cs2 from the second constant memory 404, and when the signal Cn2≧signal cs2, the signal cp is output.

FIG. 5 is a block diagram showing the other side of the operation system in which the focusing lens is driven every predetermined scan of the deflection device.
, 19) is applied to the decoding circuit 111 of the decoding section 11 and used as a decoding start signal.

With this configuration, the decoding circuit is caused to perform a decoding operation every predetermined number of deflection operations of the deflection device, and if the decoding is successful, it outputs a signal dt indicating decoded data to the host computer, and outputs an off signal to operate the device. to stop.

In the embodiments shown in FIGS. 2 and 3, the focal position of the focus adjustment lens 13 is changed each time the deflection device scans, whereas in this embodiment, the focal position of the focus adjustment lens 13 is changed every time the deflection device scans. Rather, the focus position is changed after scanning a certain number of times.

Therefore, with the configuration of this embodiment, although the time required for reading is longer, the reliability of reading can be improved by outputting a signal when the contents of multiple decodes match.

FIG. 6 is a block diagram showing an example of still another embodiment of the present invention in which the focusing lens is driven by a decoding failure, and the same reference numerals as in each of the above embodiments correspond to the same parts.

In the figure, a deflection device drive circuit 5 receives a drive signal from a drive signal generation circuit 4 which inputs a signal S1 from a control circuit circuit 1, and supplies a signal bi to the deflection device (18, 19).
The supply of the signal bi is stopped by the off signal.

The deflection devices (18, 19) output a signal eg for each deflection.

The photoelectric conversion unit drive circuit 2 receives the signal s2 from the control circuit 1.
In response, the signal Oe is supplied to the photoelectric conversion section 23, and the supply of the signal Oe is continued until the off signal is input.

The photoelectric conversion unit 23 receives the signal Oe from the photoelectric conversion unit drive circuit 2.
The light emitting element 12 is driven by the light emitting element 12, and the converted signal of the light receiving element 16 is outputted to the switch 402 as a signal es.

The focus adjustment device drive circuit 7 outputs the signal fc to the focus adjustment device 13 in response to the signal fail from the decoding section 11 . The focus adjustment device 13 performs focus adjustment by a predetermined amount by inputting the signal rc.

The binarization circuit 10 receives the output signal es from the photoelectric conversion section 23.
is converted into a binary level signal di and provided to the decoding section 11.

The decoding circuit 111 that receives the signal di decodes it and outputs the decoded data via the output circuit 112.
It outputs from the terminal 22 to the host computer. At the same time, the output circuit 112 outputs an off signal to stop the operation of the device.

On the other hand, in the off signal generation circuit 201, a counter circuit 202 counts the signal eg from the deflection device (18, 19), and uses the count result as a signal Cn to the comparator 202.
supply to.

Further, a certain value (the total number of scans) is set in the constant memory 203, and this value is supplied to the comparator 204.

Comparator 204 compares output signal cn of counter circuit 202 with signal cs indicating a set value of constant memory 203, and outputs an off signal when signal cn≧signal cs.

This off signal stops the operation of the device in the same way as the off signal from the output circuit 112 described above.

Now, the switch 402 supplies the output signal eS from the photoelectric converter 23 to the binarization circuit 10 via the amplifier 9 in response to the input of the signal eg from the deflection device, and also supplies the signal eS from the focus adjustment device drive circuit 7. The input of rc stops the supply of the signal es to the binarization circuit. That is, the focus adjustment device 1
3 continues to supply the signal es to the binarization circuit 10.

Further, in the configuration of this embodiment, the decoding circuit 111 of the decoding unit 11 decodes the binary level signal di, and when the decoding is successful, outputs the signal dc indicating the decoded data, which is the decoding result, to the output circuit 112.
However, when the decoding fails, that is, when the decoding is not possible, a signal fail indicating the failure is sent.
is outputted to the focus adjustment device drive circuit 7, the supply of the signal es is stopped as described above, and the focus adjustment device 13 is controlled by the control circuit to move the position of the focus adjustment lens 14.

FIG. 7 is a block diagram showing still another embodiment of the present invention in which the focus adjustment lens is driven in response to a decoding failure, and the same reference numerals as in each of the above embodiments correspond to the same parts.

The main part of the operation of the configuration shown in FIG. 7 is almost the same as that shown in FIG. The present invention is provided to the decoding circuit 111 of the decoding section 11 as a decoding start signal.

In this way, in the embodiment described in FIGS. 6 and 7 above, the focus adjustment lens 1 is removed only when decoding fails.
If decoding is successful, the next barcode can be read immediately without changing the focus position.

According to this method, when reading a large number of barcodes in succession, workers can quickly read them without changing the distance between the barcode scanner and the media on which the barcodes are attached. .

In this way, when reading successive barcodes, it is possible to work more quickly if the focal point position does not change.

〔Effect of the invention〕

As explained above, according to the present invention, since the autofocus mechanism is controlled based on the fact that the barcode is correctly decoded, the barcode can be read with optimal focus in accordance with the print quality of the barcode and the surface condition of the media. This makes it possible to provide a laser scanner with excellent functionality that greatly improves the reading rate.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram for explaining an embodiment of the present invention, FIG. 2 is a configuration diagram for explaining an example of an operation method configured to continuously drive a focusing lens, and FIG. 3 4 is a block diagram illustrating another example of an operation method in which the focus adjustment lens is driven continuously, and FIG. A configuration diagram showing an example, FIG. 5 is a configuration diagram showing another example of the operation method in which the focus adjustment lens is driven every predetermined scan of the deflection device, and FIG. 6 is a configuration diagram showing another example of the operation method in which the focus adjustment lens is driven due to a decoding failure. FIG. 7 is a block diagram showing an example of yet another embodiment of the present invention having a configuration in which the focus adjustment lens is driven by a decoding failure. 8 is an explanatory diagram of barcode reading by a laser scanner, FIG. 9 is an explanatory diagram of the resolution of the laser scanner, and FIG. 10 is an explanatory diagram of the beam spot diameter and read signal waveform at the barcode display position. . 1... Control circuit, 2... Photoelectric conversion unit drive circuit, 3... Light emitting element driver, 4...
... Drive signal generation circuit for deflection device, 5 ... Deflection device drive circuit, 6 ... Drive signal generation circuit for focus adjustment device drive circuit, 7 ... Focus adjustment device Drive circuit, 8...Preamplifier, 9...Amplification circuit, 10...Binarization circuit, 11...Decoding section, 12...・Laser light emitting element, 13・
...Voice coil motor, 14... Focus adjustment lens, 15... Hole mirror 16...
... Light receiving element, 17 ... Fixed lens, 18
...Reflection mirror 19 ... Galvano scanner, 20 ... Barcode display surface, 21a,
21b... Switch, 22... Output terminal to host computer. Power resolution of Pyrography Diagram Rebsumo

Claims (1)

[Claims] A laser emitting element, a laser emitting element driving means for driving the laser emitting element, a focusing means, an optical deflection means for scanning a barcode display on a medium with a laser beam emitted from the laser emitting element, and an optical deflection means. In a laser scanner, the laser scanner includes a deflection driving means for driving a bar code, a light receiving element for receiving reflected light from a bar code display, and a decoding means for processing an output signal of a light emitting element. A laser scanner comprising: an adjustment means; and means for stopping the focus adjustment operation of the focus adjustment means in response to the success of the decoding of the barcode scanned by the optical deflection means by the decoding means. .