JP2788559B2 - 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. 12 and 13 show the configuration of a conventional bar code reader. 12, a laser beam emitted from a He-Ne laser enters a polygon mirror 311 through an opening provided in a concave mirror 301, and according to the rotation of the polygon mirror 311 as shown in FIG. Pattern combining mirrors 303a, 303b, 303c
Are sequentially scanned. These pattern combining mirrors 303a
The laser beam reflected by .about.303c is reflected by the mirror 304 and enters the fixed hologram 305 attached to the reading window (see FIG. 12), and is bent by the diffraction action of the fixed hologram 305, and FIG.
The bar code 103 attached to the object 102 such as a product is illuminated while drawing various scanning patterns as shown in FIG. A part of the light scattered by the barcode is incident on the concave mirror 301 by reversing the optical path of the laser beam as shown by a dotted line in FIG. 12, and is detected by the concave mirror 301 and the mirror 341. The reading processing unit 343 guides the bar code 102 to the bar code 102 based on a change in the output of the photodetector 542.
Is read.

In this configuration, a bar code reader is thinned by obtaining a scanning pattern (indicated by an arrow A in FIG. 14) 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 305 with an imaging function, the scattered light from the barcode 103 can be efficiently detected by the photodetector 342.
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. 15 shows a configuration of a hologram disk type bar code reader. In FIG. 15, a laser beam enters through an opening provided in a condenser lens 441, is bent by a mirror 401, and enters a hologram disk 402. While continuously changing the angle of the hologram disk 402 with respect to the radial direction, the hologram disk 4
A hologram having a pattern for diffracting a laser beam is provided diagonally below 02.

Therefore, by rotating the hologram disk 402, the laser beam scans several pattern combining mirrors 403 in order, and after being reflected by these pattern combining mirrors 403, is repelled by the mirror 404 and read. Emitted through window 405.
Usually, three to five pattern combining mirrors 403 are provided, but one pattern combining mirror 403 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.
02 is illuminated. Further, a part of the light scattered by the barcode 102 is shown in FIG.
As shown by a dotted line, the light travels backward in the above-described optical path and is condensed on the photodetector 442 by the condensing lens 441. Based on the output of the photodetector 442, the reading processing unit 443 executes 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. 16 shows the configuration of the laser beam printer.

In FIG. 16, light emitted from a semiconductor laser 501 is shaped into a beam by a collimator lens 502 and then obliquely enters the lower surface of a hologram disk 503. Due to the diffraction effect of the hologram disk 503, the above-described laser beam is bent obliquely upward and, in accordance with the rotation of the hologram disk 503, the tangential direction of its circumference (FIG. 1).
6 (indicated by arrow B). Further, each hologram provided on the hologram disk 503 has an image-forming action together with the above-described diffraction action, and forms an image on the photosensitive drum 504 with the laser beam bent obliquely upward, so that it is sharp on the photosensitive drum 504. 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)
As shown in FIG. 17, the oscillation wavelength changes continuously according to changes in temperature and output, and the oscillation mode changes at a predetermined temperature, so that the oscillation wavelength changes discontinuously. In the vicinity of the transition temperature of the oscillation mode, the semiconductor laser enters a mode competition state, and light beams having wavelengths corresponding to two adjacent oscillation modes are simultaneously emitted.

On the other hand, the beam scanning mechanism using a hologram as described above is based on the premise that the wavelength of a 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 dependence.

[0016] For example, when the wavelength of the laser beam incident on the hologram disk 503 of the laser beam printer shown in FIG. 16 is changed from the wavelength lambda _i of the wavelength lambda _{i + 1,} 1
As indicated by the dotted line in FIG. 6, the direction of the laser beam emitted from the hologram disk 503 changes,
The above image formation position is shifted. Further, when the mode competition state as described above occurs, the beam diameter of the laser beam is substantially expanded, so that the image on the photosensitive drum 504 is blurred.

The same applies to the bar code reader shown in FIGS. 12 and 15, 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 a hollow-in-type bar code reading apparatus, as shown in FIG. 18, in a mode conflict 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 for use, there is known a method 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 transition temperature of the oscillation mode described above 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, even when the Peltier element is driven in accordance with the detection of the mode competition state, a temperature change required to escape from the mode competition state occurs depending on the setting of the energizing time to the Peltier element. There is a possibility that the temperature may not be changed or a temperature change more than necessary may be given.

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.

[0022]

FIG. 1 is a diagram showing a configuration of a semiconductor laser light source device according to the first to third aspects of the present invention.

According to the first aspect of the present invention, a detecting means 111 for detecting a mode competition state of the semiconductor laser 101 based on a part of the laser light emitted from the semiconductor laser 101,
Temperature adjusting means 112 for adjusting the temperature of the semiconductor laser 101 by a predetermined adjustment amount in response to the input of a detection signal indicating that the mode competition state has been detected, and semiconductor adjustment by the temperature adjusting means 112 based on the detection signal. Laser 1
A determination unit 113 for determining whether or not 01 has escaped from the mode competition state; and a change unit 114 for changing the adjustment amount by the temperature adjustment unit 112 in response to the input of the determination result indicating that it has not escaped from the mode competition state. It is characterized by having.

According to a second aspect of the present invention, in the semiconductor laser light source device according to the first aspect, the determining means 113 causes the semiconductor laser 101 to escape from the mode competition state based on a time change of the detection signal from the detecting means 111. It is characterized in that it is configured to determine whether or not it has been done.

According to a third aspect of the present invention, in the semiconductor laser light source device according to the first aspect, the storage means 121 for storing the temperature adjustment amount changed by the change means 114 and providing the temperature adjustment amount by the temperature adjustment means 112 is provided. It is characterized by having.

FIG. 2 is a diagram showing a configuration of a semiconductor laser light source device according to a fourth aspect. According to a fourth aspect of the present invention, in the semiconductor laser light source device according to the first aspect, the semiconductor laser
A determination unit 131 that determines the oscillation mode of the semiconductor laser 101 based on a part of the laser light emitted from the laser light source 01 is provided. It is characterized in that it is configured to determine whether the semiconductor laser 101 has escaped from the mode competition state based on this.

FIG. 3 is a diagram showing the configuration of a bar code reading device according to a fifth embodiment. According to a fifth aspect of the present invention, the bar code 103 attached to the object 102 is scanned by scanning the semiconductor laser light source device 110 according to the first aspect and 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 141 for illuminating and reading means 142 for reading the barcode 103 based on a change in intensity of scattered light from the barcode 103.

[0028]

According to the first aspect of the present invention, when the mode competition state is detected by the detecting means 111, the temperature of the semiconductor laser 101 is adjusted by the temperature adjusting means 112, and according to the judgment result by the judging means 113 at this time. Change means 1
By changing the adjustment amount described above, the adjustment amount required for escape from the mode competition state can be learned without excess or deficiency. After the appropriate adjustment amount is obtained in this way, the temperature adjusting means 112 gives a proper temperature change to the semiconductor laser 101 in response to the detection of the mode competition state. And it can be stabilized in a single mode state.

Further, the judging means 113 comprises the detecting means 111
Since it is determined whether or not the mode competition state has been escaped based on the time change of the detection signal from the
The determination can be made accurately in consideration of the time required for the adjustment process performed by the control unit.

Also, by storing the adjustment amount obtained in the learning process in the storage means 121, it becomes possible to hold the appropriate adjustment amount even after the power supply of the semiconductor laser light source device is turned off. When the power is turned on, the semiconductor laser 101 is held in a state where an appropriate adjustment amount is maintained from the beginning.
Can be controlled.

Further, by inputting the oscillation mode discrimination result obtained by the discrimination means 131 to the judgment means 113,
The determination unit 113 can accurately distinguish between a case where the mode competition state could not be escaped by the adjustment processing by the temperature adjustment unit 112 and a case where the mode transition to another mode competition state has occurred.

According to the fifth aspect of the present invention, since the laser beam stabilized in a single mode state by the semiconductor laser light source device 110 is incident on the beam scanning mechanism 141, the laser beam is not affected by the wavelength dependence of the beam scanning mechanism 141. Object 10
2 can be illuminated with a narrowly focused laser beam. Therefore, the reading means 142 can read the barcode 103 with the same accuracy as the case where the He-Ne laser device is used as a light source by performing the same reading processing as in the related art.

[0033]

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 (lens) 502 to emit a laser beam.

A part of the above-described laser beam is diffracted and separated by the hologram 211 and forms an image on the light receiving surface of the CCD array 212 as shown by a dotted line in FIG.

Here, since the diffraction angle by the hologram 211 depends on the wavelength of the incident laser beam, when the semiconductor laser 101 is in the mode competition state, as shown in FIG. 5, the oscillation mode i (wavelength λ _i ) And light in the oscillation mode i + 1 (wavelength λ _{i + 1} ) form images on the CCD array 212 at different positions. Thus, for example, CC
A peak detector 213 is provided for detecting the peak position of the incident light intensity by comparing the output of each element of the D array 212 and outputting a detection signal indicating whether or not two or more peaks have been detected as a mode competition detection result. The configuration may be such that

Thus, the hologram 211 and the CC
The function of the detection unit 111 can be realized by the D array 212 and the peak detection unit 213. In FIG. 4, the Peltier element 221, the driving circuit 222, and the timer 223 form a temperature adjusting unit 112, and the driving circuit 2 is controlled in response to a detection signal indicating that a mode competition state has been detected.
22 supplies the drive current of a predetermined current value to the Peltier element 221 for the energization time set in the timer 223. The Peltier element 221 is disposed adjacent to the semiconductor laser 101 described above, and changes the temperature corresponding to the energy given to the Peltier element 221 by the drive current described above.
Is provided.

The timer 231 and the determination circuit 232 form the determination means 113. The timer 231 starts operating in response to a detection signal indicating that a mode competition state has been detected, and a predetermined time has elapsed. A timeout signal indicating this is sent to the determination circuit 232. Further, the determination circuit 232 performs a determination process described later in response to the timeout signal, and
It is determined whether or not the semiconductor laser 101 has escaped from the mode competition state based on the temperature change given by the controller. To change the supplied power supply time.

In FIG. 4, the changing means 114 comprises a register 241, an adder 242, a subtractor 243, and a multiplexer 244. The adder 242 and the subtractor 243 store the contents of the register 241 and a predetermined numerical value. The addition process and the subtraction process with Δ are performed, and the multiplexer 244 sends the calculation result corresponding to the above-described change instruction to the above-described temperature adjustment unit 112 and sets the result in the timer 221. The multiplexer 244
Is input to and held in the register 241, and is set in the timer 231 of the determination means 113 described above.

Next, a description will be given of a determination process by the above-described determination circuit 232 and a process of changing the energization time by the changing unit 114. FIG. 6 is a flowchart showing the operation of learning the temperature adjustment amount in the semiconductor laser light source device of the present invention.

[0041] Here, in the initial state, the timer 231 of timer 223 and determining unit 113 of the temperature adjusting means 112 is initially set value T _O of the energization time,
Further, the numerical value corresponding to the initial value T _O is changed
Is stored in the register 241.

First, the determination circuit 232 detects
Is read (step 601), and it is determined whether or not a mode race condition has occurred (step 6).
02). In the case of a negative determination in step 602, steps 601 and 602 are repeated.

On the other hand, in the case of an affirmative determination in step 602, the drive circuit 222 operates according to the above-described detection signal, and the drive current is supplied to the Peltier element 221 for the energization time t set in the timer 223 ( Step 6
03). At this time, the timer 23 of the determination means 113
In response to the time-out signal from the timer 231, the determination circuit 232 reads the detection signal from the detection unit 111 (step 604), and based on the detection signal, determines whether the mode competition state has been escaped. It is determined whether or not there is (Step 605).

Here, if the detection signal read in step 604 indicates that the mode competition state has been detected, it is determined that the mode of the semiconductor laser 101 has been changed because the drive current to the Peltier element 221 was too short. This indicates that the temperature change required to escape the race condition was not provided.

Therefore, the judgment circuit 232 determines in step 60
When the detection signal read in step 4 indicates that the mode competition state has been detected, it is determined that the mode competition state detected in step 602 has not been escaped (negative determination in step 605), and On the other hand, extension of the energization time may be instructed (step 606). In response to this, the output of the adder 242 is selected by the multiplexer 244 of the changing means 114, and a new energizing time extended by the time δ corresponding to the above-mentioned numerical value Δ is transmitted.

On the other hand, when the detection signal indicating that the mode is the single mode is read in step 604, the semiconductor laser 101 is changed by the temperature change given by the temperature adjusting means 112.
Indicates that the system has once escaped from the mode competition state detected in step 602.

In this case, the determination circuit 232 makes an affirmative determination in step 605, and sets a predetermined delay time τ in the timer 231 (step 607). Thereafter, in response to the time-out signal from the timer 231, the detection signal is read again to determine whether or not a mode contention state exists (step 608).

If it is determined in step 608 that the mode is in the mode competition state, the time of the drive current to the Peltier element 221 is too long, and the temperature of the semiconductor laser 101 greatly changes. Indicates that the state has been changed. Therefore, in this case, the determination circuit 232 reduces the energization time by changing the changing unit 11.
4 (step 609). In response to this, the output of the subtractor 243 is selected by the multiplexer 244 of the changing means 114, and a new energization time reduced by the time δ is transmitted.

As described above, the steps 605 and 608 are performed with a time lag, and the time change of the detection signal is examined. The temperature adjustment by the temperature adjustment means 112 causes the semiconductor laser 101 to escape from the mode competition state. Can be accurately determined, and whether the temperature adjustment amount is excessive or deficient can be correctly determined.

Further, according to the determination result, the changing means 1
The new energization time output by the timer 14 of the temperature adjustment means 112 and the timer 23 of the determination means 113
1 and input to the register 241 of the changing means 114 and set, and the energization time is changed (step 61).
0).

For example, if a negative determination is made in step 605 after the mode competition state is detected for the first time, the energization time is set to the initial value T _O by the changing means 114 according to the processing in step 606. It is extended to the time obtained by adding τ. Further, by repeating this process, a search for an appropriate energization time is performed while extending the energization time by the predetermined time τ described above. Thus if the proper current time is detected, the result negative determination in step 608, the energization time T _E at that time is held as a result learned.

If an affirmative determination is made in step 605 first, the process proceeds to step 609, where
The search for appropriate energization time performed while shortening the conduction time by time δ by changing means 114, in the same manner, resulting proper energization time T _E is held as a result learned.

After a proper energizing time is obtained by such a learning process, in response to the detection of the mode competition state,
Since the drive current to the Peltier element 221 only during the energization time T _E is supplied, it is possible to give the excess or deficiency no temperature change in the semiconductor laser 101, it causes reliably escape mode competition state, another mode competition Transition to the state can be prevented.

As a result, the semiconductor laser 101 can be oscillated while being stabilized in a single mode, so that a semiconductor laser light source device that emits a laser beam of a stable wavelength using a visible light semiconductor laser is realized. be able to. Further, even if the characteristics of the semiconductor laser 101 change with the passage of time, it is possible to flexibly respond.

It should be noted that the present invention is not limited to the case where the amount of temperature adjustment is controlled by controlling the current supply time of the drive current, but is also applicable to the case where the amount of temperature adjustment by the temperature adjustment means 112 is controlled by changing the current value of the drive current. Can be applied. In this case, instead of the timer 223, for example, a configuration may be adopted in which the temperature adjusting unit 112 is provided with a variable resistor, and the changing unit 114 changes the current value by changing the resistance value of the variable resistor.

The temperature adjusting means 112 is not limited to the configuration using the Peltier element 221, but is configured to control the temperature of the semiconductor laser 101 by controlling the driving current supplied to the semiconductor laser 101 by a driver circuit. It may be.

As the detecting means 111, mode hopping noise (N. Chinone, T. Kuroda, T. Ohhtoshi, T. Takah)
ashi, T. Kajimura: "Mode-Hopping Noise in Index-Gui
dedSemiconductor Lasers and Its Reduction by Satur
able Absorbers ", IEEE J. Quantum Electron., VOL. QE2
A configuration may be used in which a mode race condition is detected by detecting a mode race condition.

Here, as shown in FIG. 7, the semiconductor laser 101 has a light emitting unit provided with a photodiode 201 for receiving a laser beam emitted to the side opposite to the emission window, and the output of the photodiode 201 is: It is configured to be output to the outside of the device as a monitor current indicating the optical output of the semiconductor laser 101, and it is known that the mode hopping noise described above is observed in this monitor current in a mode competition state.

Therefore, the extraction circuit 214 and the comparison circuit 215
And the extraction circuit 214
Extracts a noise component corresponding to the mode hopping noise from the above-described monitor current, and the comparing circuit 215 compares the magnitude of the obtained noise component with a predetermined threshold value. In this case, a configuration may be adopted in which a detection signal indicating that a mode competition state has been detected is output. As described above, the function of the detection unit 111 can be realized by the photodiode 201, the extraction circuit 214, and the comparison circuit 215 described above.

In accordance with the detection of the mode conflict state by the detecting means 111, the above-mentioned steps 601 to 6 are performed.
By performing the learning process of 10, the semiconductor laser 101
It can be obtained an appropriate energization time T _E for providing the temperature adjustment amount required to escape from the mode race condition. Thereby, it becomes possible to give an appropriate temperature change to the semiconductor laser 101 in accordance with the detection of the mode competition state,
The mode competition state can be surely escaped.

In this case, the detecting means 111 shown in FIG.
As described above, it is not necessary to dispose the hologram 211 and the CCD array 212 at a distance and separate them as a difference in the imaging position due to a difference in the oscillation wavelength of the semiconductor laser 101. It is possible to reduce the size of the semiconductor laser light source device as a whole. In addition, since a large-scale circuit such as a CCD array or a driving circuit for the CCD array is not required, the detection unit 111 can be realized with a small-scale circuit.

If the appropriate adjustment amount obtained by learning as described above is retained even after the power of the semiconductor laser light source device is turned off, the next time the power is turned on, the appropriate adjustment amount is set from the beginning. Obtainable.

FIG. 8 shows an embodiment of the storage means of the semiconductor laser light source device according to the third aspect. In FIG. 8, a register 251, a counter 252, and a comparison circuit 253 form a timer 223 of the temperature adjusting unit 112, and the counter 252 performs a counting operation in synchronization with a predetermined clock signal. The comparison circuit 253 sends a time-out signal to the drive circuit 222 when the contents of 251 match. The battery 254, after power down, has a structure for supplying the current required for the content backup in the register 251 are configured to hold the energization time T _E obtained by the above-described learning process.

In response to power-on, the judgment means 113
Timer 231 and register 241 of changing means 114
If the configuration is such that the contents of the register 251 are transferred to each other and the above-described energizing time _TE is set for each, after the learning process is first performed, the semiconductor laser 101 is set based on an appropriate adjustment amount immediately after power-on. Mode control can be performed.

In the above-described embodiment, the configuration in which the storage unit 121 is provided inside the timer 231 has been described. However, the configuration in which the storage unit 121 is provided outside the temperature adjustment unit 112 may be adopted.

By the way, as shown in FIG. 4, the CCD array 212 is located at a position intersecting the diffracted light of the hologram 211.
Is arranged, the oscillation wavelength of the semiconductor laser 101 can be obtained based on the image formation position of the diffracted light on the CCD array 212, and the oscillation mode itself can be determined.

FIG. 9 shows an embodiment of a semiconductor laser light source device according to the fourth aspect. In FIG. 9, the semiconductor laser light source device is formed by adding a peak detector 216 to the semiconductor laser light source device shown in FIG.
The output of one CCD array 212 is output to the peak detector 21.
6 is input.

The peak detector 216 compares the outputs of the CCD array 212 to detect the positions where the diffracted light is formed, and determines the element number of the CCD array 212 corresponding to each position of the light by the oscillation mode of the semiconductor laser 101. Is output as the information indicating. That is, the hologram 21
1, the CCD array 212 and the peak detection unit 216 implement the function of the determination unit 131.

In this case, based on the information indicating the oscillation mode obtained by the determining means 131, the determining means 113
Is obtained by the temperature adjusting process by the temperature adjusting unit 112.
It can be determined whether or not the mode conflict state has been escaped.

For example, in response to detection of a mode race condition,
The determining means 113 is provided with a holding memory 233 for holding the result of the determination of the oscillation mode by the determining means 131, and in response to the input of a detection signal indicating that the mode competition state has been detected,
The determination circuit 232 may compare the contents of the holding memory 233 with the determination result of the determination unit 131, and instruct the extension or shortening of the energization time according to the comparison result.

As a result, there is a distinction between a case where the mode competition state is escaped but the mode competition state is returned again, and a case where the adjustment amount is too large and a transition is made to the next mode competition state. Separately, the energization time can be accurately controlled in each case, and an appropriate adjustment amount can be reliably obtained.

Further, the magnitude of the deviation between the current oscillation mode of the semiconductor laser 101 and the target oscillation mode is evaluated based on the oscillation mode discrimination result obtained by the discrimination means 131 described above. The configuration may be such that the increment δ of the energization time is changed accordingly.

As described above, when it is determined whether the adjustment amount is excessive or deficient in consideration of the oscillation mode of the semiconductor laser 101 obtained by the determination unit 131, the oscillation is performed by the temperature change given to the semiconductor laser 101 by the temperature adjustment unit 112. It is possible to learn an appropriate adjustment amount while considering the direction in which the mode has changed.

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

In FIG. 10, the bar code reader is
The hollow-in-type bar code reader shown in FIG. 12 includes the semiconductor laser light source device shown in FIG. 4 as a light source device replacing the conventional He-Ne laser device. The emitted laser beam enters the polygon mirror 311 through the opening of the concave mirror 301. The polygon mirror 311 and the pattern combining mirrors 303a to 303c
The mirror 304 and the fixed hologram 305 form a beam scanning mechanism 141, which scans a laser beam while drawing various scanning patterns shown in FIG. 102
The upper bar code 103 is illuminated. The scattered light from the bar code 103 is transmitted to the concave mirror 301 and the mirror 3 in the same manner as in the conventional bar code reader.
41, and is guided to the photodetector 342. Based on a change in the output of the photodetector 342, the reading processing unit 34
3 is configured to read the barcode 103.

In this case, a hologram 211 is arranged between the collimator lens 502 and the polygon mirror 311, and a CCD array 212 is arranged at a position where the hologram 211 intersects with the diffracted light.
May be sent to the peak detection unit 213. Thus, the peak detecting unit 213 can detect the mode competition state of the semiconductor laser 101 by detecting the image forming position of the diffracted light on the CCD array 212, and accordingly, the temperature adjusting unit 112 Then, the temperature of the semiconductor laser 101 is adjusted. Further, the learning process described above by the determination unit 113 and the changing unit 114 is performed, the excess and deficiency no energization time T _E to provide the proper temperature changes in the semiconductor laser 101 is determined.

After the completion of the learning process, in response to the detection of the mode competition state, the semiconductor laser 101 is given a proper temperature change to escape from the mode competition state, and the semiconductor laser 101 is quickly moved out of the mode competition state. It is possible to prevent the laser beam incident on the beam scanning mechanism 141 from being mixed with wavelengths corresponding to a plurality of oscillation modes.

Thus, the above-described fixed hologram 30
Beam scanning mechanism 141 regardless of the diffraction effect of
It is possible to always keep the laser beam scanned narrowly in a narrow state, so that the reading processing unit 343
By performing the same processing as that of the related art on the output of the photodetector 342, the barcode 103 can be read with high accuracy.

As described above, by applying the semiconductor laser light source device of the present invention to a bar code reader, the overall size of the device can be reduced by employing a semiconductor laser as a light source without sacrificing reading accuracy. Can be.

Further, the semiconductor laser light source device of the present invention may be applied to a hologram disk type bar code reader without being limited to the hollow window type bar code reader. In this case, the laser beam emitted from the semiconductor laser light source device is coupled to the opening of the condenser lens 441 and the mirror 401.
Then, a configuration may be adopted in which the light enters the hologram disk 402 through. Thereby, the hologram disk 402
And a laser beam incident on a beam scanning mechanism 141 comprising a pattern combining mirror 403 and a mirror 404 can be prevented from being mixed with wavelengths corresponding to a plurality of oscillation modes. The laser beam scanned by the scanning mechanism 141 can be kept constantly narrowed.

The semiconductor laser light source device of the present invention may be applied to a laser beam printer. In FIG.
The configuration of an embodiment of a laser beam printer device to which the semiconductor laser light source device of claim 4 is applied is shown.

In FIG. 11, a semiconductor laser (LD) 1
After being shaped into a beam by the collimator lens 502, the light emitted from the hologram disk 503 is incident on the above-mentioned hologram disk 503 from obliquely below, is diffracted obliquely upward by the hologram disk 503, and is rotated by the hologram disk 503. Accordingly, the scanning on the photosensitive drum 504 is performed.

In this case, a hologram 211 is arranged between the collimator lens 502 and the hologram disk 503, and a CCD array 212 is arranged at a position intersecting the light diffracted by the hologram 211.
12 may be sent to the peak detectors 213 and 216. Further, in response to the detection signal from the peak detection unit 213, the temperature adjusting unit 112 gives a temperature change to the semiconductor laser 101, and based on the detection signal and the determination result of the oscillation mode by the peak detection unit 216, the determination unit 113 and a changing unit 114 has a configuration for obtaining the energization time T _E corresponding to excess or deficiency no temperature adjustment amount escape from mode competition state performing the above-described learning process.

As a result, an appropriate temperature change is given to the semiconductor laser 101 in response to the detection of the mode competition state, and the semiconductor laser 101 can be stabilized in the single mode state. make use of,
The photosensitive drum 504 can be scanned with a laser beam having a small beam diameter.

Further, the judgment means 113
The deviation between the current oscillation mode and the target oscillation mode is evaluated based on the determination result of the oscillation mode, and the energization time is extended or shortened to the changing means 114 in accordance with the obtained direction of the deviation. , It is possible to realize control for causing the semiconductor laser 101 to oscillate in a fixed oscillation mode.

In this case, it is not necessary to correct the fluctuation of the oscillation wavelength due to the fluctuation of the oscillation mode by the optical system of the beam scanning mechanism as in the related art. Equivalent print quality can be obtained.

[0087]

As described above, according to the present invention, the amount of temperature adjustment required to escape from the mode competition state can be learned based on the detection result of the mode competition state. Accordingly, the semiconductor laser can be quickly changed in temperature without any excess or shortage to escape the mode competition state and to stabilize the semiconductor laser in the single mode state. This makes it possible to apply the present invention to a barcode reader having a wavelength-dependent beam scanning mechanism, and without sacrificing the reading accuracy in the barcode reader.
The size of the entire device can be reduced by employing a visible light semiconductor laser.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a semiconductor laser light source device according to claims 1 to 3;

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

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

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

FIG. 5 is an explanatory diagram of a mode conflict state detection process.

FIG. 6 is a flowchart showing a learning operation of a temperature adjustment amount in the semiconductor laser light source device of the present invention.

FIG. 7 is a block diagram of another embodiment of the detecting means of the semiconductor laser light source device of the present invention.

FIG. 8 is a diagram showing an embodiment of the storage means of the semiconductor laser light source device according to claim 3;

FIG. 9 is a diagram showing an embodiment of a semiconductor laser light source device according to claim 4;

FIG. 10 is a block diagram showing an embodiment of a bar code reader according to claim 5;

FIG. 11 is a configuration diagram of a laser beam printer device to which the semiconductor laser light source device of the present invention is applied.

FIG. 12 is a configuration diagram of a conventional barcode reading device.

FIG. 13 is a diagram showing an arrangement of a pattern combining mirror of the barcode reading device.

FIG. 14 is an explanatory diagram of a hollow-in scanning pattern.

FIG. 15 is a configuration diagram of a hologram disk type bar code reader.

FIG. 16 is a configuration diagram of a laser beam printer device.

FIG. 17 is an explanatory diagram of transition of the oscillation mode of the semiconductor laser.

FIG. 18 is a diagram showing the spread of a beam diameter in a mode competition state.

[Explanation of symbols]

 Reference Signs List 101 semiconductor laser 102 object 103 barcode 110 semiconductor laser light source device 111 detecting means 112 temperature adjusting means 113 determining means 114 changing means 121 storing means 131 determining means 141 beam scanning mechanism 142 reading means 201 photodiode 211 hologram 212 CCD array 213,216 peak Detector 214 Extraction circuit 215, 253 Comparison circuit 221 Peltier element 222 Drive circuit 223, 231 Timer 232 Judgment circuit 233 Holding memory 241, 251 Register 242 Adder 243 Subtractor 244 Multiplexer 252 Counter 254 Battery 301 Concave mirror 303, 403 Pattern synthesis mirror 304, 341, 401, 404 Mirror 305 Fixed hologram 311 Polygon mirror 342, 442 Light Can 343,443 reading processor 402, 503 hologram disc 405 read window 502 collimating lens (lens) 504 photosensitive drum

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masanori Okawa 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Within Fujitsu Limited (58) Field surveyed (Int.Cl. ⁶ , DB name) G06K 7/10 H01S 3 / 18

Claims (5)

(57) [Claims] 1. A detecting means (111) for detecting a mode competition state of a semiconductor laser (101) based on a part of a laser beam emitted from the semiconductor laser (101), and a detection means for detecting a mode competition state. A temperature adjustment unit (112) for adjusting the temperature of the semiconductor laser (101) by a predetermined adjustment amount in response to the input of the detection signal; and the temperature adjustment unit (112) based on the detection signal.
Determining means (1) for determining whether or not the semiconductor laser (101) has escaped the mode competition state by the temperature adjustment according to (1).
13) and a changing means (114) for changing an adjustment amount by the temperature adjusting means (112) in accordance with an input of a determination result indicating that the vehicle has not escaped from the mode competition state. Laser light source device. 2. The semiconductor laser light source device according to claim 1, wherein the judging means (113) changes the mode of the semiconductor laser (101) from the mode competition state based on a time change of a detection signal from the detecting means (111). A semiconductor laser light source device characterized in that it is configured to determine whether or not it has escaped. 3. The storage device (121) according to claim 1, wherein the temperature adjustment amount changed by the change device (114) is stored and used for the adjustment process by the temperature adjustment device (112). A semiconductor laser light source device comprising: 4. The semiconductor laser light source device according to claim 1, wherein the determination unit determines the oscillation mode of the semiconductor laser based on a part of the laser light emitted from the semiconductor laser. The determination means (113) determines whether or not the semiconductor laser (101) has escaped the mode competition state based on the detection signal from the detection means (111) and the determination result by the determination means (131). A semiconductor laser light source device characterized in that the semiconductor laser light source device is configured to determine whether or not the semiconductor laser light source device determines whether or not the semiconductor laser light source device is in use. 5. The semiconductor laser light source device (110) according to claim 1, wherein a laser beam incident from the semiconductor laser light source device (110) is scanned according to the wavelength thereof to form an object (102).
A beam scanning mechanism (141) for illuminating the bar code (103) attached to the bar code, and a reading unit for performing a reading process of the bar code (103) based on a change in intensity of scattered light from the bar code (103). (142) A bar code reader, comprising: