JP2987243B2 - Optical scanning device - 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 scanning device, and more particularly, to an optical scanning device used for a POS scanner or the like using a hologram method.

[0002]

2. Description of the Related Art FIGS. 9 to 13 show a conventional example, FIG. 9 is a schematic diagram of a POS scanner, FIG. 10 is an explanatory diagram of an oscillation mode, and FIG. 11 is a mode stabilizing method of a semiconductor laser. FIGS. 12 and 13 are explanatory diagrams of a mode detection method, and FIG. 13 is an explanatory diagram of mode detection.

In the figure, 1 is a motor, 2 is a polygon mirror,
3 is a mirror for synthesizing a pattern, 4 is a mirror, 5 is a concave mirror, 6 is a glass plate for a reading window, 7 is a He-Ne laser light source, 8 is a product, 9 is a bar code, 10 is a laser beam, and 11 is a semiconductor laser. Light source, 12 is a hologram, 13
Is a laser diode (LD), 15 is a mode detection element,
Reference numeral 16 denotes a mode determination unit, 17 denotes a mode control unit, 18 denotes a Peltier element, 19 denotes a Peltier element driver, and 20 denotes a laser diode driver.

Reference numerals 3-1 and 3-2 denote mirrors for synthesizing patterns, 21 denotes a hologram for monitoring, 22 denotes a barcode for monitoring, 23 denotes a mirror, 24 denotes a photodetector, and 25 denotes a reading processing unit.

First, a conventional POS scanner is
This will be described with reference to FIG. FIG. 9A shows a POS scanner using a He-Ne laser light source, and FIG. 9B shows a POS scanner (proposed example) using a semiconductor laser light source.

The position of the He-Ne laser light source and the position of the semiconductor laser light source shown in FIG. 9 are different from the actual positions, but are shown in FIG. 9 for simplification of the drawing. Further, a photodetector and the like for detecting the reflected light from the barcode are not shown.

Conventionally, for example, a POS scanner as shown in FIG. 9A has been known as a device for reading a bar code of a product. In this POS scanner, He is used as a light source.
-Ne laser light source 7 was used.

The laser light emitted from the He—Ne laser light source 7 is shaped by a lens, becomes a laser beam 10, and enters the polygon mirror 2. Thereafter, the laser beam scanned by the polygon mirror 2 is reflected by the mirror 4 and the mirror 3 and irradiates the bar code 9 on the product 8 through the glass plate 6 provided in the window of the apparatus.

As described above, the bar code is read by the laser beam applied to the bar code 9. By the way, in recent years, there has been a demand for downsizing and price reduction of POS scanners. To this end, a POS scanner using a semiconductor laser light source as shown in FIG. 9B has been previously proposed.

The proposed POS scanner shown in FIG. 9B uses a semiconductor laser light source as a light source, and uses a hologram (hollow window) in a window frame portion of the device.

That is, in the POS scanner shown in FIG. 9B, the He—Ne laser light source 7 in FIG. 9A is replaced by a semiconductor laser light source 11 and the glass plate 6 is replaced by a hologram (hollow window) 12. .

In FIG. 9B, a laser beam emitted from a semiconductor laser light source 11 is shaped by a lens, becomes a laser beam 10, and enters the polygon mirror 2.
The laser beam scanned by the polygon mirror 2 is reflected by the mirrors 5 and 3 and is incident on a hologram (hollow window) 12 installed in the apparatus window frame.

The laser beam incident on the hologram 12 is diffracted by the laser beam and forms a scanning pattern for reading a bar code. In this case, the hologram 12 has a function of converting a simple scanning pattern created by the mirror system into a complex multidirectional scanning pattern with high readability.

The hologram 12 has a function of condensing signal scattered light returning from the bar code 9 like a lens and guiding the scattered light to a detector (not shown) to obtain a sufficiently large light amount even with a small optical system. have.

As described above, the use of the hologram technology in the POS scanner is effective for improving the performance and miniaturizing the apparatus. However, such a semiconductor laser light source as shown in FIG.
A mode hop phenomenon (a phenomenon in which the oscillation wavelength changes with temperature and optical output) peculiar to a semiconductor laser as shown in FIG.

In FIG. 10A, when the temperature rises or the optical output increases, the state (oscillation wavelength λ _i ) in the figure (wavelength λ _i and λ _{i + 1} ) competes with each other, and the oscillation wavelength The state shifts to the state of (oscillation wavelength λ _{i + 1} ). Such a phenomenon is called a mode hop phenomenon.

When the wavelength of the laser beam incident on the hologram 10 changes due to the mode hop phenomenon as described above, the diffraction angle changes and chromatic dispersion occurs, as shown in FIG. 7B. That is, in the state shown in FIG. 10A or the state shown in FIG.

However, in the state of FIG. 10A, the solid line (wavelength λ _i ) and the dotted line (wavelength λ _{i + 1} ) of FIG. 7B are simultaneously emitted, and the beam diameter of the laser beam becomes substantially large. As a result, the barcode reading resolution is reduced.

In order to stabilize the oscillation mode of the semiconductor laser, a mode stabilization method for the semiconductor laser as shown in FIG. 11 has been proposed. The outline of this method is as follows.

As shown in FIG. 11, for example, a laser diode (LD) 13, a laser diode driver 20, a lens 14, a mode detecting element 1 are provided in a POS scanner.
5, a mode determination unit 16, a mode control unit 17, a Peltier device 18, a Peltier device driver 19, and the like are provided.

In this case, the Peltier element 18 changes the temperature of the laser diode 13 so that
Place them close together. Further, the mode detection element 15 is arranged in an area irradiated with the laser beam 10 emitted from the laser diode 13.

Then, based on the signal from the mode detecting element 15, the mode determining section 16
, And sends a detection signal to the mode control unit 17. The mode control unit 17 drives the Peltier element driver 19 based on the input detection signal to control the temperature of the Peltier element 18.

By this temperature control, the laser diode 1
The temperature of 3 is controlled to stabilize the oscillation mode of the laser. For example, assume that the laser diode 13 oscillates in the state shown in FIG. It is assumed that the temperature has risen from this state and the state shown in FIG. 10 (mode competition state) has been reached.

In this oscillation mode, the mode determination unit 1
6, the temperature of the laser diode 13 is reduced by the Peltier element 18 to make the laser diode 13 oscillate.
Alternatively, the temperature is raised to bring about the oscillation state.

As described above, the oscillation mode of the semiconductor laser is detected, and when a mode conflict state appears, the oscillation mode is forcibly shifted to the preceding and succeeding single mode oscillation state (or), thereby stabilizing the oscillation mode. How to do it.

Several methods have been proposed as methods for detecting the oscillation mode. One example is shown in FIGS. 12 and 13. FIG. As shown in FIG. 12, for example, P
Mirrors for pattern synthesis 3-1 and 3- in the OS scanner
2, a concave mirror 5, a mirror 23, a polygon mirror 2, a photodetector 24, a read processing unit 25, a mode determination unit 16, a monitor hologram 21, and a monitor bar code 2.
2 is provided.

In this case, the monitor hologram 21 is arranged between the pattern combining mirrors 3-1 and 3-2. The monitor hologram 21 is, for example, a transmission hologram, and is configured to diffract incident light and form an image on the monitor barcode 22 in a plane where the polygon mirror 2 scans the laser beam.

In general, a hologram can also diffract and bend incident light that is incident almost parallel to the incident surface.
As shown in FIG. 12, by disposing the monitor hologram 21 at an acute angle to the incident beam, only a very narrow range of the laser beam is separated as the mode detection laser beam, Can be scanned.

By disposing such a monitor hologram 21, the pattern synthesizing mirrors 3-1 and 3-2 can be used.
Only a part of the laser beam incident on the bar code need be blocked, and normal bar code reading is not affected.

The monitor bar code 22 is, for example, a pattern (shade pattern) in which white band patterns and black band patterns are alternately arranged as shown in FIG. .

The direction of arrangement of these band-shaped patterns is matched with the scanning direction of the mode detecting laser beam.
It is attached to the housing of the POS scanner. The width of these band-shaped patterns may be a width corresponding to the size of the image formed on the monitor barcode 22 by the monitor hologram 21.

A part of the light scattered by the monitor bar code 22 is incident on the concave mirror 5 via the monitor hologram 22 and the polygon mirror 2 as shown by a dotted line in FIG. The light is guided to the photodetector 24 by the mirror 23.

Here, the intensity of the scattered light from the monitor bar code changes in accordance with the density of the light and shade pattern at the position where the mode detection laser beam forms an image. Therefore, when the semiconductor laser oscillates in a single mode and the mode detection laser beam is narrowed down on the monitor barcode 32, the density change inside the image on the monitor barcode 22 is small. .

For this reason, the intensity of the scattered light changes in accordance with the change in the density of the shading pattern of the monitor bar code 22. Incidentally, since the diffraction effect of the monitor hologram 21 has wavelength dependence, the diffraction angle of the monitor hologram changes according to the change of the oscillation wavelength of the semiconductor laser, and the image formation position on the monitor barcode 22 changes. Change.

Therefore, in the mode competition state, the laser beams incident on the same position on the monitor hologram 21 are diffracted according to the respective wavelengths, and form images at different positions on the monitor bar code 22. The image is blurred and becomes a large spot.

In this case, the change in the density of the scattered light inside the image on the monitor bar code 22 becomes large, so that the change in the intensity of the scattered light is not faithful to the change in the density of the shading pattern of the monitor bar code 22. .

That is, by evaluating whether or not the change in the intensity of the scattered light from the monitor bar code 22 faithfully represents the shading pattern of the monitor bar code 22,
It is possible to determine whether the semiconductor laser oscillates in a single mode or is in a mode competition state.

In particular, when the monitor hologram 21 diffracts the incident laser beam in the scanning direction, when the mode competition state occurs, the scattered light corresponding to the shading change in the scanning direction on the monitor bar code 22 is obtained. The fidelity of the waveform of the intensity change significantly decreases.

Thus, the difference in fidelity between the single mode state and the mode competition state can be emphasized, and the detection accuracy of the mode competition state can be increased. In this way, by making the output of the photodetector 24 a simple sine wave as shown in FIG. 13, the fidelity is evaluated based on the magnitude of the sine wave amplitude. Determine the mode.

That is, as shown in FIGS. 13A and 13B,
When oscillating wavelength lambda _i, or in any one of the wavelengths lambda _{i + 1} (when single-mode oscillation), because the beam diameter is narrow, the amplitude M of the scattered light intensity is large.

On the other hand, as shown in FIGS. 13C and 13D, at the time of mode competition in which beams of two wavelengths λ _i and λ _{i + 1} exist, the beam diameter is substantially reduced. Becomes larger, and the amplitude N of the scattered light intensity becomes smaller (M> N).

A mode competition state is detected from such a change in the amplitude of the scattered light intensity.

[0043]

The above-mentioned conventional apparatus has the following problems. (1) With a POS scanner using a He-Ne laser light source as shown in FIG. 9A, it is difficult to reduce the size and cost.

(2) In order to reduce the size and cost of the POS scanner, a POS scanner using a semiconductor laser and a hologram as shown in FIG. 9B has been proposed.
However, in such a POS scanner, a mode competition state in which the oscillation wavelength is not stabilized to one occurs due to a mode hop phenomenon peculiar to the semiconductor laser. In this case, the diameter of the beam emitted from the hologram increases, and the reading resolution of the barcode decreases. As a result, the barcode reading performance of the POS scanner decreases.

(3) A method of stabilizing an oscillation mode by detecting a mode competition state in the semiconductor laser has been considered (see FIGS. 11 to 13). However, in such a method, a monitor hologram is used. Must be provided,
Increases cost.

Further, it is necessary to provide a monitor hologram between the scanning mirrors, but the installation space is small.
Installation is difficult. The present invention solves such a conventional problem and stabilizes the oscillation mode of the semiconductor laser by detecting mode competition of the semiconductor laser without increasing the cost of the device and increasing the size of the device. Accordingly, it is an object of the present invention to realize a small and inexpensive holographic optical scanning device equipped with a semiconductor laser light source.

[0047]

FIG. 1 is a diagram showing the principle of the present invention, and FIG. 1A is a diagram showing the principle according to claims 1 to 3,
(B) is a principle diagram corresponding to claims 4 to 6.

In the figure, 11 is a semiconductor laser light source, 24A is a light detecting means, 31 is an optical scanning means, 33 is a code carrier to be scanned, 34 is a scanning laser beam, 35 is a scanning line, 36 is a diffraction beam, and 46A is a reflection. Means are shown.

The present invention is configured as follows in order to solve the above-mentioned problems. (1) A semiconductor laser light source 11, an optical scanning means 31 for scanning a laser beam emitted from the semiconductor laser light source within a predetermined range, and a scanning laser beam 34 scanned by the optical scanning means are deflected and emitted. An optical scanning device comprising a fixed optical element 32 having a wavelength dependency, wherein a scanning pattern having a predetermined shading pattern is provided at a position scanned by a part of a scanning laser beam deflected by the fixed optical element 32 and emitted. A scanning code carrier 33 is provided to detect whether or not the oscillation state of the semiconductor laser light source 11 is a mode competition state by detecting scattered light generated when the scanned code carrier is scanned. did.

(2) In the configuration (1), the oscillation wavelength of the semiconductor laser light source 11 is set to 700 nm or less. (3) In the configuration (1), by scanning the scanned code carrier 33, the signal light emitted from the scanned code carrier is detected using the light detecting means 24A.

(4) In the configuration (1), the code carrier to be scanned 33 is installed inside the apparatus and the fixed optical element 3
2, a reflecting means 46A for reflecting the emitted scanning laser beam is provided on the scanning laser beam emission side of the second scanning laser beam.
The scanning laser light reflected by the
The scanned code carrier 33 is scanned.

(5) In the configuration (4), the reflection means 46A
Was adhered to a part of the fixed optical element 32. (6) In the configuration (4), the mirror is fixed to the fixed optical element 32.
Was formed by evaporation.

[0053]

The operation of the present invention based on the above configuration will be described with reference to FIG. (1) In FIG. 1A, a laser beam emitted from a semiconductor laser light source 11 enters an optical scanning unit 31 and is scanned there. The scanning laser light 34 enters a fixed optical element (for example, a hologram) 32, where it is deflected (or diffracted).
It is emitted.

The scanning laser beam emitted from the fixed optical element 32 scans an object such as a bar code by drawing a scanning line 35. In this case, the scanning laser beam is moved to a position scanned by a part of the scanning laser beam. A scanned code carrier (for example, a monitor bar code) 33 is arranged.

In this way, the scanning code carrier 33 for monitoring can be scanned using the scanning laser beam used for reading a normal bar code or the like. Then, as a result of scanning by the scanning line 35, scattered light generated by a bar code or the like of the target object and scattered light generated when the scanned code carrier 33 is scanned reverses the optical path of the scanning laser beam 34. This scattered light is detected by the light detecting means 24A.

Further, by detecting the output of the light detecting means 24A, the beam diameter of the scattered light from the scanned code carrier 33 is evaluated, and based on the beam diameter, the oscillation state of the semiconductor laser light source 11 is changed to the mode. Detects if there is a race condition.

If there is a mode contention, the temperature of the semiconductor laser light source is controlled to make a song without mode contention. In this case, since a part of the fixed optical element 32 is used for monitoring, the mode competition state of the semiconductor laser can be detected by simple means without using a conventional monitoring hologram or the like. .

(2) In FIG. 1B, a scanned code carrier (for example, a bar code for monitoring) 33 is arranged inside the apparatus housing, and a reflection means (for example, a mirror) is provided at the position of the scanned code carrier 33 in FIG. 1A. 46A is installed.

In this case, a part of the scanning laser beam emitted from the fixed optical element 32 is reflected by the reflecting means 46A and reenters the inside of the apparatus. The reflected beam scans the scanned code carrier 33 installed inside the apparatus.

The scattered light from the scanned code carrier 33 travels backward in the optical path of the scanning laser beam 34 and is detected by the light detecting means 24A. In the same manner as in FIG. 1A, the mode competition state of the semiconductor laser is detected. I do.

As described above, if a part of the fixed optical element is used for monitoring, the installation space for detecting the mode competition state of the semiconductor laser can be reduced, and the cost can be prevented.

[0062]

Embodiments of the present invention will be described below with reference to the drawings. (Explanation of First Embodiment) FIGS. 2 to 5 are views showing a first embodiment of the present invention, FIG. 2 is a perspective view of a reading window portion in a POS scanner (window frame is omitted), and FIG. XY in FIG.
FIG. 4 is a partially enlarged view of FIG. 2, and FIG. 5 is an explanatory diagram of a mode conflict state detection process in the POS scanner.

In the figure, the same reference numerals as those in FIGS. 1, 9 to 12 denote the same parts. 36 is a diffraction beam, 37 is a scanning line, 38 is a hollow window, 39, 40, 41 are holograms, 43 is a window frame, and 44 is a reading window glass.

The first embodiment is an example in which the optical scanning device of the present invention is applied to a hologram type POS scanner equipped with a semiconductor laser (the same configuration as that shown in FIG. 9B). A monitor barcode (see FIG. 13) is provided on the hollow window.

As shown in FIGS. 2 and 3, a hollow window 38 is provided in a bar code reading window of the hologram type POS scanner. Hollow windows 38 are provided with holograms 39, 40, and 41, each having a different laser beam scanning direction.

Among these holograms, the monitor bar code 22 is provided at, for example, one end of the hologram 39 and within the scanning beam scanning range. That is, a part of the fixed hologram (hollow window) installed in the reading window is used for monitoring.

Further, above the hollow window 38, the PO
A window frame 43 coupled to the housing of the S scanner is provided,
The window frame 43 includes a window glass 44 constituting a reading window.
(See especially FIG. 3).

As shown in FIG. 4A, the monitor bar code 22 has a bar code pattern (FIG. 1) on one surface of the base.
0, the same pattern as the monitor barcode shown in FIG. 0), and its cross-sectional shape is substantially Ω-shaped, particularly as shown in FIG. 4B.

The above-mentioned monitor bar code 22 is placed on the hollow window 38 above the hologram 39 and straddling the hologram 39. By doing so, a gap (length L) can be provided between the hologram 39 and the barcode pattern constituting the barcode 22.

In the POS scanner having such a configuration, when a laser beam is scanned by scanning with a polygon mirror or the like, the scanning beam 34 enters the hologram 39,
The hologram is scanned by drawing a scanning line 37.

In the hologram 39, the scanning beam 34
Is diffracted, and a diffraction beam 36 is emitted. A part of the diffracted beam irradiates the pattern of the monitor barcode 22 provided at one end of the hologram 39. Another diffracted beam 36 exits from the window glass 44 and draws a scanning line 35 above.

The diffraction beam 3 drawing such a scanning line 35
In step 6, a bar code provided on a product or the like is read. Apart from reading such a barcode, a monitor barcode is also read using a part of the diffraction beam.

In this case, as described in the conventional example, if the oscillation state of the semiconductor laser is in the mode competition state,
The diffraction angle of the diffracted beam 36 changes, causing chromatic dispersion.
As a result, the beam diameter increases due to chromatic dispersion.

However, the increase in the beam diameter due to the chromatic dispersion does not appear on the hologram 39 but becomes more significant as the distance from the hologram 39 increases. Therefore, the pattern of the barcode constituting the monitor barcode 22 is set at a fixed distance L from the hologram 39.

As the hologram on which the monitor barcode 22 is set, any one of the holograms 39, 40, 41 on the hollow window 38 is selected. Need to be selected so that the beam diameters do not cross at right angles and the beam diameter increases due to chromatic dispersion in the scanning direction.

Desirably, it is effective to select a hologram in which the beam scanning direction matches the diffraction direction. Next, the process of detecting the mode competition state of the semiconductor laser is described in FIG.
It will be described based on.

The laser beam (solid line in the figure) emitted from the semiconductor laser light source 11 is scanned by the polygon mirror 2, reflected by the mirrors 3 and 4, and incident on the hologram of the hollow window 38. The scanning beam incident on the hologram is diffracted by the hologram, and the diffracted beam scans the barcode 9 provided on the product 8 (solid line in the figure).

In this case, the semiconductor laser light source 11 uses a visible light laser having an oscillation wavelength of 700 nm or less. If a laser having such a wavelength is not used, barcodes cannot be read properly.

At this time, since the monitor bar code 22 provided on the hollow window 38 is arranged in the scanning range of the diffraction beam for scanning the bar code 9, the monitor hologram 22 is formed by the diffraction beam. Also scan.

The bar code 9 provided on the product 8
The scattered light from the monitor and the scattered light from the monitor bar code 22 travel backward in the optical path of the scanning beam (dotted line in the figure) and enter the concave mirror 5.

Thereafter, the scattered light travels from the concave mirror 5 to the mirror 23, enters the photodetector 24, and is detected. The light detector 24 converts the light into an electric signal corresponding to the intensity of the incident light, and outputs the electric signal to the reading processing unit 25. The reading processing unit 25 performs a process of reading a barcode based on a signal sent from the photodetector 24.

At this time, the output signal of the photodetector 24 is taken into the mode judging section 16 and the signal of the monitor bar code 22 is detected. It is determined whether or not the laser is in a mode competition state.

(Explanation of Second Embodiment) FIGS. 6 to 8 show the second embodiment.
FIG. 6 is a sectional view of the POS scanner (only the main part), FIG. 7 is an enlarged view of each part in FIG. 6, and FIG. 8 is a modification of the monitor mirror.

In the figure, the same reference numerals as those in FIGS. 1 to 5 indicate the same parts. Reference numeral 45 denotes a housing, and 46 denotes a monitor mirror. In the second embodiment, a monitor mirror is installed at the installation location of the monitor barcode 22 in the first embodiment, and the monitor barcode installed inside the apparatus is scanned with the diffraction beam reflected by the monitor mirror. Here is an example.

As shown in FIG. 6, a monitor mirror 46 is set on the hologram 39 so as to straddle the hologram 39. This monitor mirror is located at exactly the same place as the place where the monitor barcode 22 is installed in the first embodiment.

Therefore, the monitor mirror 46 and the hologram 39 are set apart by a fixed distance. Also in this case, if the beams are installed at a certain distance, the beam diameter becomes large.

Then, the diffracted beam 36 reflected by the monitor mirror 46 is returned to the inside of the apparatus again, and the monitor bar code 22 installed inside the apparatus is scanned. For example, the monitor barcode 22 is installed at a location where the diffracted beam 36 reflected by the monitor mirror 46 reaches using an empty space or the like inside the housing 45.

FIG. 7 is an enlarged view of the monitor mirror and the monitor bar code. FIG. 7A is a sectional view of the monitor mirror, and FIG. 7B is a perspective view of the monitor bar code. As shown in the figure, the monitor mirror 46 has a substantially Ω-shaped cross section, and a mirror portion is provided in a concave portion thereof.
By doing so, the hologram 39 and the mirror portion of the monitor mirror 46 can be set apart from each other by a fixed distance.

Further, after the diffracted beam diffracted by the hologram 39 is reflected by the mirror portion, it can be returned to the direction of the monitor bar code 22 installed inside the housing 45 again.

The monitor bar code 22 is composed of a pattern in which black patterns and white patterns are alternately arranged on a substrate (a pattern similar to that shown in FIG. 10), and the diffraction beam 36 scans the pattern. It has become.

The scattered light from the monitor bar code 22 reverses the original optical path again.
As in the embodiment, it is possible to detect a mode conflict state.

With the above arrangement, the hologram 39
After the scanning beam is diffracted, the distance from the scanning beam to the monitor bar code 22 can be increased (the beam length can be increased). Therefore, the increase in the beam diameter due to the chromatic dispersion is larger than that in the first embodiment, and the detection sensitivity of the mode competition state is increased.

Next, a modification of the monitor mirror will be described with reference to FIG. 8A is an example in which the monitor mirror 46 is directly adhered on the hologram 39. FIG. In this case, there is no distance between the monitor mirror 46 and the hologram 39, but there is no problem because the distance to the monitor barcode can be increased.

FIG. 8B shows a second modification of the hologram 3.
This is an example in which a monitor mirror 46 is formed on the substrate 9 by vapor deposition. In this case, the monitor mirror becomes extremely thin. Further, a third modification of FIG.
This is an example using a reflection hologram. This reflection hologram is formed directly on the hologram 39.

According to the above modification, the monitor mirror is provided directly on the hologram, so that no member or the like for installation is required, and the monitor mirror can be made thin. Further, in this embodiment, the monitor barcode is installed using an empty space inside the housing.

Therefore, the size of the POS scanner can be reduced, and the cost can be prevented. (Other Embodiments) Although the embodiments have been described above, the present invention can be implemented as follows.

(1) The optical scanning device of the present invention can be used not only for a POS scanner but also for other similar bar code readers or other information reading devices. (2) Other than the hologram, other wavelength-dependent elements may be used as the fixed optical element.

[0098]

As described above, the present invention has the following effects. (1) Since a part of the fixed optical element (for example, hologram) provided in the reading window portion is used for monitoring, the space can be effectively used. As a result, it is possible to reduce the size of the device and prevent an increase in cost.

(2) For example, the monitor hologram 21 shown in FIG. 12 becomes unnecessary, and the number of parts of the apparatus is reduced accordingly. Also in this respect, the size of the apparatus can be reduced, and the cost can be prevented from increasing.

(3) According to the second embodiment shown in FIGS. 6 to 8, the path length of the diffracted beam emitted from the hologram 39 is increased, and the beam diameter is increased accordingly. Therefore, it is easy to detect the mode competition state of the semiconductor laser.

Further, since the barcode can be installed by using the empty space inside the housing, the space can be effectively used. (4) In particular, if the monitor mirror is configured as shown in FIG.
A member for installing the mirror is not required, so that cost increase can be prevented.

[Brief description of the drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a perspective view (a window frame is omitted) of a reading window in the POS scanner according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view in the XY direction of FIG. 2;

FIG. 4 is a partially enlarged view of FIG. 2;

FIG. 5 is an explanatory diagram of a mode conflict state detection process in the POS scanner of the first embodiment.

FIG. 6 is a sectional view of a POS scanner according to a second embodiment.

FIG. 7 is an enlarged view of each part in FIG. 6;

FIG. 8 is a modified example of the monitor mirror;

FIG. 9 is a schematic configuration diagram of a POS scanner in a conventional example.

FIG. 10 is an explanatory diagram of an oscillation mode in a conventional example.

FIG. 11 is an explanatory diagram of a mode stabilization method of a semiconductor laser.

FIG. 12 is an explanatory diagram of a mode detection method.

FIG. 13 is an explanatory diagram of mode detection.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Semiconductor laser light source 31 Optical scanning means 32 Fixed optical element 33 Code carrier to be scanned 34 Scanning laser beam 35 Scanning line 24A Light detecting means 46A Reflecting means

────────────────────────────────────────────────── ─── Continued from the front page (72) Inventor Hiroshi Yasukawa ▲ ▼ ▼ 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (58) Field surveyed (Int.Cl. ⁶ , DB name) G06K 7 / Ten

Claims (6)

(57) [Claims] 1. A semiconductor laser light source (11); an optical scanning means (31) for scanning a laser beam emitted from the semiconductor laser light source in a predetermined range; 3
4) a wavelength-dependent fixed optical element (3
An optical scanning device comprising: a scanned code carrier having a predetermined density pattern at a position scanned by a part of a scanning laser beam deflected by the fixed optical element (32); 33)
And detecting whether or not the oscillation state of the semiconductor laser light source (11) is a mode competition state by detecting scattered light generated when the scanned code carrier is scanned. Optical scanning device. 2. The semiconductor laser light source according to claim 1, wherein an oscillation wavelength of said semiconductor laser light source is less than 700 nm.
The optical scanning device according to claim 1. 3. The scanning optical system according to claim 1, wherein the scanning is performed on the scanned code carrier, and the signal light emitted from the scanned code carrier is detected using the light detecting means. Optical scanning device. 4. A reflection means (46A) for placing the scanned code carrier (33) inside the apparatus and for reflecting the emitted scanning laser light to the scanning laser beam emission side of the fixed optical element (32).
2. The optical scanning device according to claim 1, wherein the scanning laser beam reflected by the reflecting means (46A) is re-entered into the apparatus to scan the scanned code carrier (33). apparatus. 5. The reflection means (46A) is adhered to a part of a fixed optical element (32).
The optical scanning device according to claim 1. 6. The optical scanning device according to claim 4, wherein the mirror is formed by vapor deposition on a part of the fixed optical element.