JP2001235693A - Optical recorder and its controlling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an optical recorder which does not generate degradation of the print quality even if the ambient temperature changes in the optical recorder using an optical fiber array and an optical waveguide array. SOLUTION: In the optical recorder using the optical fiber array and the optical waveguide array, an optical splitter having the nearly constant light reflectance to an optical polarized light direction in which a multi-beam emitted from an optical fiber array arrangement part is split, a multi-beam photodetecting means to detect the split optical power, and a means to determine the driving current of a semiconductor laser by comparing the photodetecting signal of the multi-beam photodetecting means with a reference voltage responding to a semiconductor laser drive circuit are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording apparatus used in an electrophotographic apparatus for scanning and printing a large number of beams, that is, multiple beams emitted from a plurality of semiconductor lasers, and a control method thereof.

[0002]

2. Description of the Related Art Among electrophotographic apparatuses, a method using a multi-beam for realizing a high-speed laser printer is effective and important technology.

FIG. 2 shows an example of a laser printer using a plurality of semiconductor lasers, particularly an optical system thereof.

[0004] A semiconductor laser module 1 guides a laser beam emitted from a semiconductor laser unit 2 to an optical fiber 3 by a lens 10. The plurality of optical fibers are arranged in a line in the optical fiber array arranging section 4, and a plurality of beams emitted from the optical fiber array are used as an optical recording device, here, a multi-beam for a laser printer. That is, the array-shaped multi-beams emitted from the optical fiber array array pass through the lenses L1, L2, L3, and LC1, enter the rotary polygon mirror 5, and are collectively moved on the photosensitive drum 7 by the rotary polygon mirror 5. Scan simultaneously. Reference numeral 16 denotes a glass plate, and even if small dust or the like adheres to the fiber surface,
Optical recording can be performed. Reference numeral 6 denotes a scanning lens for narrowing the beam deflected by the rotary polygon mirror 5 as a minute spot on the photosensitive drum 7.

FIG. 3 shows a case where an optical waveguide 8 is used as an array arrangement portion. The optical waveguide 8 is provided on a quartz substrate 41, and the optical fiber 3 is connected at an optical waveguide input end 9. The synchronization signal generating photodetector 11 is for detecting a multi-beam to be scanned.

FIG. 4 shows a circuit for driving the semiconductor laser 1. The semiconductor laser LD is housed integrally with the built-in photodetector PD and the case 2, and a part 26 of the laser power emitted from the semiconductor laser is detected by the PD. In order for the photodetector for synchronizing signal generation to generate a photodetection signal,
It is necessary to irradiate the synchronous signal generating photodetector with multiple beams. That is, the laser light is always in the ON state at this place. Therefore, the output of the semiconductor laser forming a multi-beam at this timing is output to the built-in photodetector P.
D can be detected. The signal 21 in FIG. 4 gives this timing, and samples and holds the output of the built-in photodetector PD. The sampled and held signals are compared with a reference voltage, and the current level of the current source 25 is determined by the differential amplifier Diff so that these signal levels become the same level. The reference voltage input to the differential amplifier is a voltage VR
Is set by adjusting the variable resistor 23. SW turns on and off the current flowing through the semiconductor laser LD, and is driven by a data signal 22 input via the digital amplifier D.

By the way, the conventional semiconductor laser driving circuit can always keep the optical power of the semiconductor laser constant. However, in the optical system shown in FIGS. There is a problem in that the power changes when the environmental temperature of the apparatus changes, causing unevenness in light intensity between the multiple beams and deteriorating the printing quality. This is because even if the optical power of the semiconductor laser is kept constant,
This is because the laser power emitted from the optical fiber or the optical waveguide array array portion fluctuated due to a change in environmental temperature.

FIG. 5 shows the change in the ambient temperature of the laser power of each of the multiple beams emitted from the array arrangement portion. However, the optical power emitted from each of the semiconductor lasers is controlled so as to be constant even if the environmental temperature changes. As can be seen from this figure, when the environmental temperature changes, the fluctuations in the optical power of each of the multi-beams emitted from the array section are different from each other. The quality has deteriorated.

[0009]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an optical recording apparatus using an optical fiber which does not cause deterioration of print quality even when the environmental temperature changes.

[0010]

SUMMARY OF THE INVENTION There is a problem that the optical power emitted from an optical fiber or an optical waveguide array array varies even though the optical power of a beam emitted from a semiconductor laser is controlled to be constant. I do. This is because the accuracy required for the alignment between the laser beam incident on the optical fiber and the optical fiber, and the alignment between the optical fiber and the waveguide in the optical system shown in FIG. It was found that the slight misalignment of submicron caused by the fluctuation of the laser power emitted from the array arrangement portion.

In order to solve the above problems, the present invention provides:
A semiconductor laser module for guiding a laser beam emitted by a semiconductor laser to an optical fiber; an optical fiber array array in which optical fibers from a plurality of semiconductor laser modules are arrayed; In an optical recording device that uses an optical system that guides a beam onto a photosensitive material and a laser drive circuit that modulates each of a plurality of semiconductor lasers according to a data signal, a multi-beam emitted from an optical fiber array array is split. A light splitter having a substantially constant light reflectivity with respect to the direction of light polarization, a multi-beam light detection means for detecting the split light power, and a light detection signal of the multi-beam light detection means in a semiconductor laser drive circuit. Means for determining a drive current of the semiconductor laser by comparing with a corresponding reference voltage is provided.

According to another aspect of the present invention, there is provided a semiconductor laser module for guiding a laser beam emitted from a semiconductor laser to an optical fiber, an optical fiber array arrangement section in which optical fibers from a plurality of semiconductor laser modules are arranged in an array, In an optical recording device using an optical system for guiding a multi-beam emitted from an optical fiber array array portion onto a photosensitive material and a laser driving circuit for optically modulating each of a plurality of semiconductor lasers according to a data signal, an optical fiber array is provided. An optical splitter for splitting a multi-beam emitted from the array, a quarter-wave plate between the optical fiber array and the optical splitter, a multi-beam light detector for detecting the split optical power, and a multi-beam light The drive current of the semiconductor laser is determined by comparing the light detection signal of the detection means with the corresponding reference voltage in the semiconductor laser drive circuit. Characterized in that a means for.

According to another aspect of the present invention, laser beams emitted from a plurality of semiconductor lasers are guided to corresponding optical waveguides, respectively.
An optical waveguide array arrangement section in which optical waveguides are arranged in an array, an optical system for guiding a multi-beam emitted from the optical waveguide array section onto a photosensitive material, and light modulation of each of a plurality of semiconductor lasers corresponding to a data signal. A multi-beam light detecting means for detecting the optical power of the multi-beam emitted from the optical waveguide array arrangement portion, and driving the light detection signal of the multi-beam light detecting means with a semiconductor laser. A means for determining a drive current of the semiconductor laser by comparing with a corresponding reference voltage in the circuit is provided.

According to another aspect of the present invention, there is provided a semiconductor laser module for guiding a laser beam emitted from a semiconductor laser to an optical fiber, an optical fiber array arrangement section in which optical fibers from a plurality of semiconductor laser modules are arranged in an array, Insertion / detachment in an optical recording device using an optical system that guides a multi-beam emitted from an optical fiber array array onto a photosensitive material and a laser drive circuit that optically modulates a plurality of semiconductor lasers according to data signals. A photodetector having a mechanism for performing the operation, an A / D converter, and a memory. When the photodetector is inserted, the photodetection signal of the photodetector is stored in the memory after A / D conversion, and the photodetector is detached. Sometimes, the drive current of the semiconductor laser is determined by comparing the contents of the memory with a corresponding reference voltage in the semiconductor laser drive circuit.

[0015]

FIG. 1 shows an optical system according to the present invention using an optical fiber array element.

The multi-beam emitted from the optical fiber array array 4 enters a light splitter 40. The beam transmitted through the beam splitter 40 is subjected to optical recording by the same optical system as already described with reference to FIG. The beam reflected by the light splitter 40 is incident on a single light detector 30 as a multi-beam light detecting means, and the light output is detected. By the way, an optical fiber generally has an axially symmetric refractive index. Therefore, the polarization directions of the light emitted from the optical fiber are different among the optical fibers constituting the multi-beam, and are affected by the vibration of the apparatus, a change in the environmental temperature, etc. fluctuate. For this reason, it is necessary to use a light splitter that splits a beam with a constant reflectance even if the polarization directions of the multi-beams incident on the light splitter are different. It is desirable that the variation of the reflectance is ± 10% or less, and the light splitter having such characteristics can be manufactured by means of multilayer coating.

Further, even when the reflectivity of the light splitter greatly differs in the polarization direction, a means for completely and isotropically changing the polarization direction of the multi-beam emitted from the multi-beam array may be employed. To do this, a quarter-wave plate 42 may be inserted between the array arrangement section and the optical splitter 40 as shown in FIG.

FIG. 7 shows a laser drive circuit used in the above-described optical system of the present invention. For simplicity, the case of two lasers will be described. One of the semiconductor lasers 2A and 2B emits light during a blanking time, for example, when light scanning is started and a time until the scanning of the synchronization signal generating photodetector or the photosensitive material is started. For example, when it is desired to detect the light output of the semiconductor laser 2A emitted from the array arrangement part in a certain scan, the semiconductor laser 2A is set to emit light at a certain time within the blanking time. Then, the sample and hold signal 21A is input to the sample and hold circuit 28A at the timing when the semiconductor laser 2A emits light, and the light detection signal of the photodetector 30 is sampled and held. The sampled and held signal is compared with a reference voltage, and the current level of the current source 25A is determined by the differential amplifier Diff so that these voltage levels become the same level. The reference voltage input to the differential amplifier is adjusted by the variable resistor 23A.

In another optical scanning, the semiconductor laser 2B
The semiconductor laser 2B is set to emit light at a certain time within the blanking time in order to detect the light output from the array arrangement section due to the above. Then, the sample hold signal 21B is input to the sample hold circuit 28B at the timing when the semiconductor laser 2B emits light, and the light detection signal of the photodetector 30 is sampled and held. The sampled and held signal is compared with a reference voltage, and the current level of the current source 25B is determined by the differential amplifier Diff so that these voltage levels become the same level. The reference voltage input to the differential amplifier is adjusted by the variable resistor 23B.

By taking the above method, even if the environmental temperature fluctuates and the arrangement error between the semiconductor laser and the optical fiber slightly occurs, the optical output from the array arrangement portion does not fluctuate, and good optical recording is possible. Become.

FIG. 6 shows another optical system of the present invention using an optical waveguide element. This optical system is the same as the conventional optical system of FIG. 3 described above, except that a semi-transparent mirror 31 and a photodetector 30 as multi-beam light detecting means are provided. The multi-beam emitted from the optical waveguide array arrangement section 4 is detected by a single photodetector 30. If the semiconductor laser drive circuit of FIG. 7 described above is used, the environmental temperature fluctuates, and the semiconductor laser and the optical fiber or optical waveguide are changed. Even if there is a slight arrangement error between the wave paths, the optical output from the array arrangement portion does not fluctuate, and good optical recording becomes possible.

FIG. 8 shows another embodiment of the present invention. In this optical system, the optical detector 30 as a multi-beam light detecting means is inserted into the optical system by the mechanism while the optical recording apparatus is at rest. After the photodetector 30 is inserted, the plurality of semiconductor lasers emit light in order, and the optical power emitted from the array arrangement portion is detected by the inserted photodetector. Light detector 30
The other optical systems are the same as those described in FIG.
FIG. 9 shows a semiconductor laser drive circuit of the present invention used in this optical system. When detecting the optical power from the array portion by the semiconductor laser 2A with the photodetector 30, the semiconductor laser 2A is first energized by the signal 22A, and the light emitted from the array portion is detected by the photodetector 30, and the A / A The digital signal is converted by the D converter 31. The digitally converted optical output signal is stored in the memory 33A in accordance with an instruction based on the signal 36A. The data stored in the memory 33A is converted to an analog signal by a D / A converter, and is converted to a differential amplifier Di.
The current level of the current source 25 is determined by comparison with the reference voltage by ff. When the above-described series of procedures for the semiconductor laser 2A is completed, the current level for driving the semiconductor laser 2B is determined by the same procedure.

[0023]

According to the apparatus of the present invention, even if the alignment between the laser light incident on the optical fiber and the optical fiber and the alignment between the optical fiber and the waveguide are slightly shifted due to the fluctuation of the environmental temperature, The laser power of each of the multi-beams emitted from the array arrangement portion does not change, and an optical recording device with stable printing quality can be realized.

[Brief description of the drawings]

FIG. 1 shows an optical recording apparatus using a multi-beam by the optical fiber array element of the present invention.

FIG. 2 shows an optical recording apparatus using a multi-beam using a conventional optical fiber array element.

FIG. 3 shows an optical recording apparatus using a multi-beam using a conventional optical waveguide element.

FIG. 4 shows a conventional semiconductor laser drive circuit.

FIG. 5 is a diagram showing an example in which, even when a semiconductor laser is controlled at a constant optical power, the optical power of each of the multi-beams emitted from the array arrangement portion fluctuates due to a change in environmental temperature.

FIG. 6 shows an optical recording apparatus using a multi-beam by the optical waveguide device of the present invention.

FIG. 7 is a diagram illustrating a multi-beam semiconductor laser drive circuit according to the present invention.

FIG. 8 shows an optical recording apparatus using multiple beams by the optical fiber array element of the present invention.

9 shows a multi-beam semiconductor laser drive circuit of the present invention used in the recording apparatus shown in FIG.

[Explanation of symbols]

1: semiconductor laser module, 2: semiconductor laser, 3:
Optical fiber, 4: optical fiber array arrangement part, 31: semi-transmissive mirror, 5: rotating polygon mirror, 6: scanning lens, 7: photosensitive drum, 8: optical waveguide, 9: coupling part between optical fiber and optical waveguide, 16: A glass plate adhered to the optical waveguide array array portion, 10: a spot array formed on a photosensitive drum, 11:
Synchronous signal generating photodetector, 15: optical scanning line scanned by multiple beams, L1, L2, L3: spherical lens, LC1:
Cylindrical lens, LD: semiconductor laser, PD: built-in photodetector as optical power detection means, 23: variable resistor, 26:
Laser light incident on the built-in photodetector PD from the semiconductor laser, VC: supply voltage, SH: sample and hold circuit, D
iff: differential amplifier, D: digital amplifier, SW: switch circuit, 25: current source, 30: photodetector as multi-beam light detection means, A / D: analog-digital converter, D / A: digital- Analog converter, M: memory.

Continued on the front page F-term (reference) 2C362 AA03 AA12 AA53 AA54 AA61 BA25 BA56 BA67 BA83 CB76 2H045 AA01 BA02 BA22 BA32 CA88 CA97 CB22 CB33 CB35 CB42 5C051 AA02 CA07 DB09 DB25 DB30 DC04 DE04 DE15 DE03 5C0710 DA03 HA13 HB02 HB06 UA06 UA11 5C074 AA02 BB03 CC22 CC26 DD08 DD16 EE02 GG04 GG05 GG07 GG08

Claims (4)

[Claims] 1. A semiconductor laser module for guiding a laser beam emitted by a semiconductor laser to an optical fiber, an optical fiber array arrangement section in which optical fibers from a plurality of semiconductor laser modules are arranged in an array, and an optical fiber array arrangement. In an optical recording device that uses an optical system that guides a multi-beam emitted from a section onto a photosensitive material and a laser drive circuit that modulates each of a plurality of semiconductor lasers according to a data signal, the laser beam is emitted from an optical fiber array array section. Splitter having a substantially constant light reflectivity with respect to the direction of light polarization for splitting a multi-beam, a multi-beam light detecting means for detecting the split light power, and a light detection signal from the multi-beam light detecting means. Means for determining the drive current of the semiconductor laser by comparing with a corresponding reference voltage in the laser drive circuit. The optical recording apparatus according to claim. 2. A semiconductor laser module for guiding a laser beam emitted by a semiconductor laser to an optical fiber, an optical fiber array array in which optical fibers from a plurality of semiconductor laser modules are arrayed, and an optical fiber array array. In an optical recording device that uses an optical system that guides a multi-beam emitted from a section onto a photosensitive material and a laser drive circuit that modulates each of a plurality of semiconductor lasers according to a data signal, the laser beam is emitted from an optical fiber array array section. Splitter for splitting a multi-beam to be split, a quarter-wave plate between the optical fiber array section and the splitter, multi-beam light detecting means for detecting the split light power, and light from the multi-beam light detecting means. Means for determining a drive current of the semiconductor laser by comparing the detection signal with a corresponding reference voltage in the semiconductor laser drive circuit; The optical recording apparatus, characterized in that. 3. A laser beam emitted from a plurality of semiconductor lasers is guided to a corresponding optical waveguide, and an optical waveguide array arrangement part in which the optical waveguides are arranged in an array, and a multi-beam emitted from the optical waveguide array arrangement part are formed. In an optical recording device using an optical system for guiding light on a photosensitive material and a laser drive circuit for optically modulating each of a plurality of semiconductor lasers according to a data signal, the optical power of a multi-beam emitted from an optical waveguide array array portion is controlled. Multi-beam light detection means for detecting, and means for determining a drive current of the semiconductor laser by comparing a light detection signal of the multi-beam light detection means with a corresponding reference voltage in the semiconductor laser drive circuit. An optical recording device characterized by the following. 4. A semiconductor laser module for guiding a laser beam emitted from a semiconductor laser to an optical fiber, an optical fiber array array in which optical fibers from a plurality of semiconductor laser modules are arrayed, and an optical fiber array array. An optical recording device using an optical system that guides a multi-beam emitted from a unit onto a photosensitive material and a laser drive circuit that optically modulates each of a plurality of semiconductor lasers according to a data signal, has a mechanism for inserting and removing It has a light detection means, an A / D converter, and a memory. When the light detection means is inserted, the light detection signal of the light detection means is converted into an A / D signal.
An optical recording device which stores the data in a memory after D conversion and compares the content of the memory with a corresponding reference voltage in a semiconductor laser driving circuit when the light detecting means is attached / detached, thereby determining a driving current of the semiconductor laser. Control method.