JP2788561B2 - Semiconductor laser light source device and bar code reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser light source device using a semiconductor laser. Barcode readers and laser printers are required to be small and inexpensive, so it is necessary to reduce the size of mechanically movable parts such as a laser beam scanning mechanism. Have been. Accordingly, in a laser printer device, a light source device using an infrared semiconductor laser is used in place of a gas laser such as a He-Ne laser, thereby realizing the miniaturization of the entire device. On the other hand, since many products with barcodes that are difficult to read with infrared light are on the market, a visible light source is suitable as the light source of the barcode reader, and the optical scanning device can be downsized by using an infrared semiconductor laser. The method of doing was not applied.

However, in recent years, since a visible light semiconductor laser having an oscillation wavelength of 700 nm or less has been commercialized, a light source device using the semiconductor laser is employed to reduce the size and cost of the entire bar code reader. It is desired.

[0003]

2. Description of the Related Art FIGS. 14 and 15 show the structure of a conventional bar code reader. 14, a laser beam emitted from a He-Ne laser enters a polygon mirror 504 through an opening provided in a concave mirror 503, and according to the rotation of the polygon mirror 504, as shown in FIG. Pattern synthesis mirrors 505a, 505b, 505c
Are sequentially scanned. These pattern combining mirrors 505a
The laser beam reflected by .about.505c is reflected by the mirror 506 and enters the fixed hologram 507 attached to the reading window (see FIG. 14), and is bent by the diffraction action of the fixed hologram 507, and FIG.
The bar code 132 attached to the object 131 such as a product is illuminated while drawing various scanning patterns as shown in FIG. A part of the light scattered by the bar code is incident on the concave mirror 503 by reversing the optical path of the above-mentioned laser beam as shown by a dotted line in FIG. 14, and the light is detected by the concave mirror 503 and the mirror 541. The reading processing unit 543 is guided to the bar code 132 based on the change in the output of the photodetector 542.
Is read.

In this configuration, a bar code reader is made thinner by obtaining a scanning pattern (indicated by an arrow A in FIG. 16) in a direction perpendicular to the reading window by a diffraction action of a hologram fixed to the reading window. That is,
This is called the hollow-in method. In addition, by providing the fixed hologram 507 with an image forming function, the scattered light from the bar code 132 can be efficiently detected by the photodetector 542.
It is possible to collect light.

Further, a disk provided with a hologram having a plurality of different patterns in the circumferential direction (hereinafter, referred to as a hologram disk) is rotated by a motor, and the laser beam is scanned by irradiating the hologram disk with the laser beam. There is also a method, which is called a hologram disk method.

FIG. 17 shows a configuration of a hologram disk type bar code reader. In FIG. 17, a laser beam enters through an opening provided in a condenser lens 641, is bent by a mirror 601, and enters a hologram disk 602. While continuously changing the angle of the hologram disk 602 with respect to the radial direction, the hologram disk 6
A hologram having a pattern for diffracting a laser beam is provided diagonally below 02.

Therefore, by rotating the hologram disk 602, the laser beam scans several pattern combining mirrors 603 in order, and after being reflected by these pattern combining mirrors 603, is repelled by the mirror 604 and read. Emitted through window 605.
Usually, three to five pattern combining mirrors 603 are provided, but one pattern combining mirror 603 is shown as a representative in the figure.

As a result, various scanning patterns are obtained in the same manner as in the above-described hollow-in system, and the object 1 is scanned by a laser beam that is drawn and scanned.
The barcode 132 on 31 is illuminated. A part of the light scattered by the barcode 132 is shown in FIG.
As shown by a dotted line, the light travels in the above-described optical path, and is condensed on the photodetector 642 by the condensing lens 641. Based on the output of the photodetector 642, the reading processing unit 643 Is read.

Here, since the hologram can have an image-forming function as well as the above-described diffraction function, by using the hologram disk 402 as the scanning means, an image-forming optical system is separately provided to read the image. There is no need to stop down the laser beam emitted from the window, and the optical scanning device can be downsized.

This hologram disk type optical scanning device is also used in a laser printer. FIG. 18 shows the configuration of the laser beam printer.

In FIG. 18, light emitted from a semiconductor laser 701 is obliquely incident on the lower surface of a hologram disk 703 after being shaped into a beam by a collimator lens 702. Due to the diffraction effect of the hologram disk 703, the above-described laser beam is bent obliquely upward, and according to the rotation of the hologram disk 703, the tangential direction of its circumference (FIG. 1).
8 (indicated by arrow B). Further, each hologram provided on the hologram disk 703 has an image forming action together with the above-described diffraction action, and forms an image on the photosensitive drum 704 with the laser beam bent obliquely upward, so that it is sharp on the photosensitive drum 704. It is configured to obtain a perfect image.

As described above, by replacing a scanning mechanism, which has conventionally been composed of a scanning element such as a polygon mirror or a galvano mirror and an optical system for imaging such as a fixed mirror and a lens, with a beam scanning mechanism using a hologram, a bar scanning is realized. Code readers and laser beam printers have been downsized.

[0013]

By the way, as described above, the miniaturization of the beam scanning mechanism has been realized.
The diameter of the oscillation tube of the He-Ne laser used as a light source is relatively large, and the size of the barcode reader is limited by the size of the oscillation tube of the He-Ne laser. ing. Therefore, in order to further reduce the size of the barcode reader, it is necessary to employ a visible light semiconductor laser as a light source.

However, a semiconductor laser having an oscillation wavelength of 700 nm or less (hereinafter simply referred to as a semiconductor laser)
The oscillation mode changes according to a change in temperature or output, and the oscillation wavelength changes. For example, the temperature of the semiconductor laser is changed from the temperature T _i of the temperature T _{i + 1,} the oscillation mode is shifted to the oscillation mode i + 1 from the oscillation mode i, thereby, as shown in FIG. 19, the oscillation wavelength is the wavelength lambda _i To a wavelength λ _{i + 1} . In the course of the change from the temperature T _i to the temperature T _{i + 1} , a mode competition state occurs in which the two oscillation modes are arranged side by side. In this state, light beams having wavelengths corresponding to the two oscillation modes are simultaneously emitted.

On the other hand, the beam scanning mechanism using the hologram described above is based on the premise that the wavelength of the laser beam is constant. This is because the diffraction effect used to deflect the direction of the laser beam is an operation having a very high wavelength dependency.

[0016] For example, when the wavelength of the laser beam incident on the hologram disk 703 of the laser beam printer shown in FIG. 18 is changed from the wavelength lambda _i of the wavelength lambda _{i + 1,} 1
As shown by the dotted line in FIG. 8, the direction of the laser beam emitted from the hologram disk 703 changes,
The above image formation position is shifted. Further, in the mode competition state as described above, the beam diameter of the laser beam is substantially expanded, so that the image on the photosensitive drum 704 is blurred.

The same applies to the bar code readers shown in FIGS. 14 and 17, but in the bar code reader, a relatively large error is allowed with respect to the position of the scanning pattern drawn by the laser beam. The main problem is that the beam diameter of the laser beam expands due to the mode competition state. In particular, in the hollow-type bar code reader, as shown in FIG. 20, in a mode competition state, the beam diameter expands in the scanning direction and the resolution is reduced, so that the bar code reading accuracy is significantly deteriorated. .

Therefore, simply replacing the light source with a semiconductor laser causes various problems as described above due to the instability of the semiconductor laser. In exchange for the downsizing of the apparatus, reading accuracy and print quality are sacrificed. Will be.

On the other hand, as a technique for fixing a semiconductor laser in a single oscillation mode, a method is known in which a temperature control element such as a Peltier element is arranged adjacent to the semiconductor laser to keep the temperature of the semiconductor laser constant. Have been. But,
Since there is variation among the elements of the semiconductor laser, the temperature at which the transition of the oscillation mode occurs varies depending on the semiconductor laser element. Therefore, if the temperature set for the Peltier element is determined uniformly, there is a possibility that the state of the semiconductor laser is fixed to the mode competition state. Further, a circuit for driving the Peltier element is required separately from the driving circuit of the semiconductor laser, and the circuit scale of the light source device is increased.

An object of the present invention is to provide a semiconductor laser light source device capable of stably oscillating a semiconductor laser in a single mode. It is another object of the present invention to provide a small-sized bar code reader by applying the light source device.

[0021]

FIG. 1 is a diagram showing a configuration of a semiconductor laser light source device according to the present invention. The invention according to claim 1 is based on a separation unit 111 that separates a part of a laser beam emitted from the semiconductor laser 101 and emits the part as a mode detection laser beam, based on a wavelength of light included in the mode detection laser beam. A mode discriminating means 112 for discriminating the oscillation mode of the semiconductor laser 101;
01, the drive current supplied to the semiconductor laser 10 is changed.
Control means 113 for controlling the first oscillation mode to the target oscillation mode.

FIG. 2 is a diagram showing the configuration of the semiconductor laser light source device of the second to fourth aspects. The invention according to claim 2 is based on a separation unit 111 that separates a part of a laser beam emitted from the semiconductor laser 101 and emits the laser beam as a mode detection laser beam, based on a wavelength of light included in the mode detection laser beam. Detecting means 121 for detecting a mode competition state of semiconductor laser 101, and detecting means 121
And a control unit 122 that changes the drive current supplied to the semiconductor laser 101 in accordance with the detection result by the control unit 122 and controls the oscillation mode of the semiconductor laser 101.

According to a third aspect of the present invention, in the semiconductor laser light source device according to the second aspect, the control means 122 normally supplies a predetermined reference current to the semiconductor laser 101 and waits after a mode competition state is detected. It is characterized in that a predetermined drive current different from the reference current is supplied to the semiconductor laser 101 for a predetermined time.

According to a fourth aspect of the present invention, in the semiconductor laser light source device according to the second aspect, the control means 122 controls the reference current and a predetermined drive current different from the reference current each time a mode competition state is detected. Is switched and supplied to the semiconductor laser 101.

FIG. 3 is a diagram showing a configuration of a bar code reading device according to a fifth aspect. According to a fifth aspect of the present invention, the bar code 132 attached to the object 131 is scanned by scanning the semiconductor laser light source device 110 according to the second aspect with a laser beam incident from the semiconductor laser light source device 110 according to the wavelength. It is characterized by comprising a beam scanning mechanism 133 for illuminating and reading means 134 for performing a barcode reading process based on a change in intensity of scattered light from the barcode 132.

[0026]

According to the first aspect of the present invention, the mode discriminating means 112 discriminates the oscillation mode of the semiconductor laser 101 based on the wavelength of the mode detecting laser beam separated by the separating means 111, and performs control according to the discrimination result. By changing the drive current supplied to the semiconductor laser 101 by the means 113,
By controlling the optical output of the semiconductor laser 101, the oscillation mode of the semiconductor laser 101 can be stabilized to the target oscillation mode.

According to a second aspect of the present invention, the detecting means 121 detects the mode competition state based on the wavelength of the mode detecting laser beam separated by the separating means 111, and the control means 122
However, by changing the drive current in accordance with the detection result, the optical output of the semiconductor laser 101 can be changed to escape from the mode competition state.

Further, the control means 122 supplies a predetermined drive current to the semiconductor laser 101 for a predetermined time after the mode competition state is detected, thereby giving a predetermined energy change to the semiconductor laser 101 and causing the mode competition. It is possible to escape from the state and oscillate in a single mode.

Further, the control means 122 switches the reference current and the predetermined drive current each time the mode competition state is detected, thereby giving a predetermined energy change to the semiconductor laser 101 to escape from the mode competition state. And can be oscillated in a single mode.

According to the fifth aspect of the present invention, since the semiconductor laser light source device 110 emits a laser beam from the semiconductor laser 101 oscillating in a single mode, regardless of the wavelength dependency of the beam scanning mechanism 133. A bar code 132 on an object 131 with a narrowly focused laser beam
Can be illuminated. Therefore, the reading means 134
Can read the barcode 132 with the same accuracy as before, based on the intensity change of the scattered light from the barcode 132, and reduce the size of the barcode reader without sacrificing the reading accuracy. Can be.

[0031]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 4 shows the configuration of an embodiment of the semiconductor laser light source device of the first aspect.

In FIG. 4, the semiconductor laser light source device comprises:
The laser beam from the semiconductor laser (LD) 101 is shaped by a collimator lens 702 to emit a laser beam.

A part of the above-mentioned laser beam is diffracted by the hologram 211 corresponding to the separating means 111 as shown by a dotted line in FIG.
It is configured to form an image on the 12 light receiving surfaces. Hereinafter, the laser beam diffracted by the hologram 211 is referred to as a mode detection laser beam.

Here, the angle of diffraction by the hologram 211 depends on the wavelength of the incident laser beam. Therefore, when the semiconductor laser 101 is oscillating in the oscillation mode i (wavelength λ _i ), the oscillation mode i + 1 (wavelength λ _i When the laser beam oscillates at ( ₊₁ ), as shown in FIG. 5, the imaging positions of the mode detecting laser beam are different positions on the CCD array 212, respectively. Therefore, the wavelength can be obtained from the imaging position of the mode detection laser beam, and the oscillation mode corresponding to this wavelength can be determined.

For example, when the semiconductor laser 101 is oscillating in each oscillation mode, the mode detecting laser beam is C
To form an image on a corresponding element of the CD array 212,
The hologram 211 and the CCD array 212 described above are arranged, and the peak detector 213 detects the CCD array 212.
The element whose output has a peak value among the respective elements may be detected as the imaging position. In this case, the configuration may be such that the oscillation mode corresponding to the element number obtained by the peak detection unit 213 is output as a determination result.

Thus, the hologram 211 and the CC
The function of the mode detection unit 112 can be realized by the D array 212 and the peak detection unit 213. In addition,
The beam splitter may be used as the separation unit 111, and the mode detection unit 112 may be configured to split the mode detection laser beam using a spectroscope or the like.

In FIG. 4, the comparison circuit 221 and the driver circuit 222 correspond to the control means 113, and the comparison circuit 221 compares the above-described determination result with a predetermined threshold value. , The driver circuit 222 changes the drive current supplied to the semiconductor laser 101.

For example, the number of the element of the CCD array 212 corresponding to the wavelength in the predetermined oscillation mode is set as a threshold value in the comparison circuit 221, and the measurement result input by the comparison circuit 221 is used as the threshold value. If it does not match, the driver circuit 222 may determine that an oscillation mode shift has occurred and change the drive current.

In this manner, the drive current supplied to the semiconductor laser 101 can be changed in accordance with the result of the discrimination by the mode discriminating means 112, whereby the light output of the semiconductor laser 101 is changed and the semiconductor laser 101 is changed. 101
Oscillation mode can be controlled.

In particular, the driver circuit 222 fixes the semiconductor laser 101 to a predetermined oscillation mode by increasing or decreasing the drive current in accordance with the direction of the oscillation mode shift detected by the comparison circuit 221 described above. Oscillation can be stably performed in the state.

In this way, a semiconductor laser light source device that can obtain a stable oscillation wavelength using a visible light semiconductor laser having a wavelength of 700 nm or less can be realized. The driver circuit 222 is an indispensable element for driving the semiconductor laser 101. By using the driver circuit 222 to control the oscillation mode of the semiconductor laser 101, a driver circuit 222 is used. As compared with the above, the increase in the amount of hardware can be suppressed, and the price can be reduced and the size can be reduced.

This semiconductor laser light source device is suitable for a device which does not allow a shift of a scanning position of a laser beam and an expansion of a beam diameter due to a change in an oscillation mode of a semiconductor laser, such as a laser beam printer device shown in FIG. .

FIG. 6 shows an embodiment of a laser beam printer device to which the semiconductor laser light source device shown in FIG. 4 is applied. In FIG. 6, the laser beam printer device includes:
A hologram 221 corresponding to the separating means 111, a hologram 211, a CCD array 212, and a peak detector 21 are provided in a conventional laser beam printer (see FIG. 18).
3 and a comparison circuit 221.
And a control circuit 113 including a driver circuit 222, and the driver circuit 222
Is supplied with a drive current.

In this case, the hologram 211 is disposed between the collimator lens 702 and the hologram disk 703, and the hologram 211 is disposed in the same manner as in the above-described embodiment.
What is necessary is just to arrange | position the CCD array 212 in the position which intersects the laser beam for mode detection diffracted by.

Thus, as described above, the output of the semiconductor laser 101 is controlled by the mode determining means 112 and the control means 113, and the oscillation mode of the semiconductor laser 101 can be stabilized at a predetermined oscillation mode. Therefore, it is possible to prevent the displacement of the scanning position of the laser beam on the photosensitive drum 704 and the blurring of the image. Therefore, unlike the related art, it is not necessary to compensate for the wavelength fluctuation due to the fluctuation of the oscillation mode by the optical system, and the design of the optical system is facilitated, and the price of the laser beam printer can be reduced.

On the other hand, when the semiconductor laser light source device is applied to the bar code reading device, unlike the above-described laser beam printer device, only the mode competition state needs to be avoided, and the oscillation mode is fixed to a predetermined oscillation mode. No control is required.

Hereinafter, a method for avoiding the mode competition state in the semiconductor laser light source device will be described. FIG. 7 shows a configuration diagram of an embodiment of the semiconductor laser light source device of claim 2.

In FIG. 7, the semiconductor laser light source device comprises:
As in the case of the semiconductor laser light source device shown in FIG.
1 to separate the mode detection laser beam,
An image is formed on the D array 212.

In FIG. 7, this hologram 21
1, the CCD array 212, the comparison circuit 321, and the judgment circuit 3
22 forms the detecting means 121, and the comparing circuit 3
21 sequentially compares the output of each element of the CCD array 212 with a predetermined threshold value, and the determination circuit 322 determines whether or not the outputs of the plurality of elements exceed the above-described threshold value by the comparison circuit 321. It has a configuration.

Here, if a value sufficiently larger than the noise level of the CCD array 212 is set in the comparison circuit 321 as the above-mentioned threshold value, the elements of the CCD array 212 that can obtain an output exceeding this threshold value are in the mode. Only the element corresponding to the imaging position of the detection laser beam. Therefore,
The presence of a plurality of corresponding elements indicates that the laser beam for mode detection contains light having a wavelength corresponding to a plurality of oscillation modes, that is, the semiconductor laser 101 is in a mode competition state. I have.

Therefore, the above-described determination circuit 322 indicates whether or not the outputs of the plurality of elements have exceeded the threshold value by, for example, logic “1” and logic “0”, respectively. May be sent to the driver circuit 323 corresponding to the control unit 122 as a detection result of the control unit 122.

According to the detection result, the driver circuit 32
By changing the drive current supplied to the semiconductor laser 101 by the semiconductor laser 101, the optical output of the semiconductor laser 101 fluctuates, and it is possible to escape from the mode competition state.

In this way, the oscillation mode can be controlled to escape from the mode competition state in response to the detection of the mode competition state. Therefore, the semiconductor laser 101 can be kept in the single mode, and the unstable property can be obtained. A stable semiconductor laser light source device can be realized using the visible light semiconductor laser.

Next, a method of controlling the drive current by the control means 122 will be specifically described. FIG. 8 shows an embodiment of the control means 122 according to the third aspect.

In FIG. 8, the control means 122 includes a switching signal generating circuit 420 for generating a switching signal according to the detection result obtained by the detecting means 121, and a predetermined current different from the reference current I ₀ according to the switching signal. A driver circuit 424 for switching and outputting the drive current I ₁ is provided.

As described above, the detection means 121
In the case where whether or not a mode competition state is detected is indicated by logic "1" and logic "0", as shown in FIG. 8, a switching signal generation circuit is formed by an AND gate 421, a D-type flip-flop 422, and a timer 423. 420 may be formed. In this case, the switching signal generation circuit 420 is configured to read the detection result of the above-described detection unit 121 in response to the input of the clock signal, and output the output of the D-type flip-flop 422 as a switching signal. Also,
The timer 423 starts operating in synchronization with the rise of the output of the AND gate 421, and clears the D-type flip-flop 422 after a predetermined time τ. The driver circuit 424 outputs the reference current I ₀ when the logic “0” is input as the switching signal,
When the logic “1” is input, a predetermined drive current I ₁ may be output and supplied to the semiconductor laser 101.

Thus, normally, the reference current I ₀ can be supplied to the semiconductor laser 101, and the predetermined drive current I ₁ can be supplied for a predetermined time τ in response to the detection of the mode competition state. Thus, the optical output of the semiconductor laser 101 changes as shown in FIG. However, in FIG.
The optical output P ₀ is an optical output corresponding to the reference current I ₀ , and is an optical output corresponding to the optical output P ₁ and the driving current I ₁ .

Here, the time τ set in the timer 423 is the energy represented by (P ₁ −P ₀ ) × τ, which corresponds to the energy required for the semiconductor laser 101 to escape from the mode competition state. What is necessary is just to determine. In this case, according to the drive current from the driver circuit 424, while the semiconductor laser 101 is emitting light output P _1, the semiconductor laser 101 becomes a single mode to escape mode competition state, then the emitting light output P ₀ of the wavelength corresponding to the single mode. Further, as the above-described clock signal, a clock signal having a cycle sufficiently longer than the time τ may be input to the switching signal generation circuit 420.

In this case, the driver circuits 424 need only switch and output the drive currents I ₀ and I _1, and there is no need to provide a structure for continuously changing the drive currents.
The configuration of the driver circuit can be simplified. Also,
Since the switching signal generation circuit 421 can be realized by a simple logic circuit as described above, a stable semiconductor laser light source device can be realized without increasing the circuit scale.

Since the energy required to escape from the mode competition state is very small, the light output P
The difference between ₀ and P ₁ may be small, and the optical output of the semiconductor laser 101 can be kept almost constant.

FIG. 10 is a block diagram showing an embodiment of the control means 122 according to the fourth aspect. Referring to FIG.
Is the switching signal generation circuit 4 of the control unit 122 shown in FIG.
In place of 20, a switching signal generation circuit 430 is provided.

The switching signal generating circuit 430 is formed of an AND gate 431 and a T-type flip-flop 432, and detects the detecting means 12 according to the input of the clock signal.
1 is read. In this case, the output of the T-type flip-flop 432 is inverted in synchronization with the rising edge of the clock signal each time the logic "1" indicating the mode conflict state is input as the output of the detection means 121. Type flip-flop 432
May be input to the driver circuit 424 as a switching signal.

In response to the switching signal, driver circuit 42
4, the reference current I ₀ and the predetermined drive current I ₁ are alternately output, so that the optical output of the semiconductor laser 101 changes every time a mode competition state is detected, as shown in FIG.

In this case, too, the driver circuit 4 having a simple configuration is used.
24, a predetermined energy change is applied to the semiconductor laser 1.
01, it is possible to escape from the mode competition state, and a stable semiconductor laser light source device can be realized without increasing the circuit scale. Further, the light amount of the output laser beam can be kept substantially constant.

Next, a bar code reader to which the semiconductor laser light source device of claim 2 is applied will be described. FIG.
Next, an embodiment of the bar code reader according to the present invention is shown in FIG.

In FIG. 12, the bar code reader is
In the conventional bar code reader shown in FIG. 14, a hologram 211 corresponding to the separating means 111, a detecting means 121 comprising this hologram 211, a CCD array 212, a comparing circuit 321 and a judging circuit 322, and a switching signal generating circuit 420 And control circuit 122 comprising driver circuit 424
Are added. Further, a semiconductor laser 101 and a collimator lens 702 are provided in place of the He-Ne laser, and the above-described driver circuit 424 supplies a driving current to the semiconductor laser 101.

In this case, the above-described hologram 211 may be disposed between the collimator lens 702 and the concave mirror 503, and the CCD array 212 may be disposed at a position intersecting the laser beam diffracted by the hologram 211. Thus, based on the output of the CCD array 212, the mode competition state can be detected by the comparison circuit 321 and the determination circuit 322.

The switching signal generation circuit 421 and the driver circuit 422 switch the output of the semiconductor laser 101 in accordance with the detection result, and
01 is controlled, and the oscillation mode of the semiconductor laser 101 can be kept in a single mode.

As a result, it is possible to keep the beam diameter of the laser beam scanned by the beam scanning mechanism including the element having a diffractive effect like the fixed hologram 507 small. Therefore, by applying the semiconductor laser light source device of claim 2 to a bar code reader, it is possible to reduce the size of the bar code reader without sacrificing the reading accuracy.

In this case, the concave mirror 5
03 and the mirror 541 guide the scattered light from the bar code 132 to the photodetector 542, so that the reading processing unit 543 is provided.
Can read the barcode 132 from the change in the output of the photodetector 542 with the same accuracy as a conventional barcode reader.

The semiconductor laser light source device described above may be applied to a hologram disk type bar code reader. FIG. 13 is a block diagram showing another embodiment of the bar code reader according to the fifth aspect.

In FIG. 13, the bar code reader is
In the conventional bar code reader shown in FIG. 17, a hologram 211 corresponding to the separating unit 111, a detecting unit 121 including the hologram 211, the CCD array 212, the comparing circuit 321 and the determining circuit 322, and a switching signal generating circuit Control means 12 comprising 420 and driver circuit 424
2 is added. Further, a semiconductor laser 101 and a collimator lens (lens) 702 are provided instead of the He-Ne laser, and the above-described driver circuit 424 supplies a driving current to the semiconductor laser 101.

In this case, the hologram 211 described above may be arranged between the collimator lens 702 and the condenser lens 641, and the CCD array 212 may be arranged at a position intersecting the laser beam diffracted by the hologram 211. From the output of the CCD array 212, the comparison circuit 3
21 and the determination circuit 322 can detect a mode conflict state.
2, the oscillation mode of the semiconductor laser 101 can be controlled.

Thus, the hologram disk 602,
Since the laser beam scanned by the beam scanning mechanism including the pattern synthesizing mirror 603 and the mirror 604 can be kept in a narrowed state, the condensing lens 641,
The bar code 132 is read by the reading means 134 including the photodetector 642 and the reading processing section 643 with the same accuracy as the conventional one.
Can be read.

[0075]

As described above, according to the present invention, the oscillation current of the semiconductor laser is changed by changing the drive current supplied to the semiconductor laser in accordance with the result of discriminating the oscillation mode of the semiconductor laser or the result of detecting the mode competition state. Oscillation mode control for controlling the mode to stabilize the semiconductor laser to the target single mode and oscillation mode control for escaping the mode competition state are possible. A simple semiconductor laser light source device can be realized. Further, by applying this semiconductor laser light source device to a barcode reader, it is possible to reduce the size of the barcode reader without sacrificing the reading accuracy.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a semiconductor laser light source device according to claim 1;

FIG. 2 is a diagram showing a configuration of a semiconductor laser light source device according to claims 2 to 4;

FIG. 3 is a diagram showing a configuration of a bar code reader according to claim 5;

FIG. 4 is a view showing the configuration of an embodiment of the semiconductor laser light source device according to claim 1;

FIG. 5 is an explanatory diagram of a wavelength measuring method.

FIG. 6 is a configuration diagram of an embodiment of a laser beam printer device to which the semiconductor laser light source device of claim 1 is applied.

FIG. 7 is a configuration diagram of an embodiment of a semiconductor laser light source device according to claim 2;

FIG. 8 is a block diagram showing an embodiment of the control means of the invention according to claim 3;

FIG. 9 is a diagram showing a change in light output.

FIG. 10 is a block diagram of an embodiment of a control means according to the invention of claim 4;

FIG. 11 is a diagram showing a change in light output.

FIG. 12 is a block diagram of an embodiment of a bar code reader according to claim 5;

FIG. 13 is a block diagram showing another embodiment of the bar code reader according to claim 5;

FIG. 14 is a configuration diagram of a conventional barcode reading device.

FIG. 15 is a diagram showing an arrangement of a pattern combining mirror of the barcode reader.

FIG. 16 is an explanatory diagram of a hollow-in scanning pattern.

FIG. 17 is a configuration diagram of a hologram disk type bar code reader.

FIG. 18 is a configuration diagram of a laser beam printer device.

FIG. 19 is an explanatory diagram of a mode transition of the semiconductor laser.

FIG. 20 is a diagram showing the spread of a beam diameter in a mode competition state.

[Explanation of symbols]

 Reference Signs List 101 semiconductor laser (LD) 110 semiconductor laser light source device 111 separating means 112 mode discriminating means 113, 122 control means 121 detecting means 131 object 132 barcode 133 beam scanning mechanism 134 reading means 211 hologram 212 CCD array 213 peak detecting parts 221 and 321 Comparison circuit 222, 323, 424 Driver circuit 322 Judgment circuit 420, 430 Switching signal generation circuit 421, 431 AND gate 422 D-type flip-flop 423 timer 432 T-type flip-flop 503 Concave mirror 504 Polygon mirror 505, 603 Pattern synthesis mirror 506, 541 , 601 and 604 Mirror 507 Fixed hologram 542 and 642 Photodetector 543 and 643 Reading processing unit 602 and 703 Hologram disk 605 Reading window 641 Condenser lens 702 Collimator lens 704 Photosensitive drum

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G06K 7/10 H01S 3/096 H04N 1/113 H04N 1/23 103

Claims (5)

(57) [Claims] 1. A separation means (111) for separating a part of a laser beam emitted from a semiconductor laser (101) and emitting the laser beam as a mode detection laser beam, and a wavelength of light included in the mode detection laser beam. A mode discriminator (112) for discriminating the oscillation mode of the semiconductor laser (101) based on the driving current supplied to the semiconductor laser (101) according to a discrimination result by the mode discriminator (112). A semiconductor laser light source device comprising: a control unit (113) for changing the oscillation mode of the semiconductor laser 101 to a target oscillation mode. 2. A separation means (111) for separating a part of a laser beam emitted from a semiconductor laser (101) and emitting the laser beam as a mode detection laser beam, and a wavelength of light included in the mode detection laser beam. Detecting means for detecting a mode competition state of the semiconductor laser based on the detection result, and changing a drive current supplied to the semiconductor laser in accordance with a detection result by the detecting means. And a control means (122) for controlling an oscillation mode of the semiconductor laser (101). 3. The semiconductor laser light source device according to claim 2, wherein the control means (122) normally supplies a predetermined reference current to the semiconductor laser (101) and waits for a predetermined time after a mode competition state is detected. A semiconductor laser (101) for supplying a predetermined drive current different from the reference current to the semiconductor laser (101) only during the time. 4. The semiconductor laser light source device according to claim 2, wherein the control means (122) switches between a reference current and a predetermined drive current different from the reference current each time a mode competition state is detected. A semiconductor laser light source device configured to supply the semiconductor laser light to the semiconductor laser (101). 5. The semiconductor laser light source device (110) according to claim 2, wherein an object (131) is scanned by a laser beam incident from the semiconductor laser light source device (110) according to its wavelength.
A beam scanning mechanism (133) for illuminating the bar code (132) attached to the bar code; and a reading means (1) for performing a bar code reading process based on a change in intensity of scattered light from the bar code (132).
34) A bar code reader comprising: