JPH0519197A - Optical device using semiconductor laser array - Google Patents

Abstract

PURPOSE:To provide an optical device by which the light intensity of each light emitting point of a semiconductor laser array is independently monitored without making the device larger. CONSTITUTION:This device is provided with a light source part using the semiconductor laser array 1 where plural light emitting sources capable of optical modulation independently are arrayed in a direction parallel with a bonding surface, a collimating optical system 2 for collimating plural luminous fluxes from the light source part, a deflector which deflects the luminous flux from the optical system 2 in a specified direction, and an optical system by which the deflected luminous flux from the deflector is formed into the image on a specified photosensitive medium simultaneously with scanning. Then, a semi- transparent mirror 11 which divides the luminous flux from the light emitting source in a different direction from the optical axis of the optical system 2, an image-formation optical system 12 by which the divided luminous flux from the mirror 11 is formed into the image at specified intervals, and a detector 14 which detects the light intensity of each image-forming light from the optical system 12 are provided between the light emitting source of the array 1 and the optical system 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device using a semiconductor laser array applicable to a high speed writing optical scanning device such as a laser printer, a digital copying machine and a laser facsimile.

[0002]

2. Description of the Related Art A light source section using a semiconductor laser array in which a plurality of light emitting sources capable of independently modulating light in a direction parallel to a bonding surface are used, and a collimating optical system for collimating a plurality of light beams from the light source section. There is an optical device having a deflector for deflecting the light beam from the collimating optical system in a predetermined direction and an optical system for simultaneously imaging and scanning the deflected light beam from the deflector on a predetermined photosensitive medium.

In FIGS. 9 and 10 showing one embodiment thereof, for example, the emitted and diverged beams from the semiconductor laser 1 are collimated by a collimator lens 2 and made incident on one surface of a rotary polygon mirror 3 as a deflector. Reflection from the rotating polygon mirror 3,
The polarized light is imaged and scanned on the surface 5 to be scanned by the optical system 4 such as an fθ lens. During this scan,
By applying modulation to the semiconductor laser array 1, a desired image can be obtained on the surface 5 to be scanned.

By using an array-shaped light source for such an apparatus, various advantages such as high-speed processing are brought about. Here, the array-shaped light source means, for example, as shown in FIG. 11, a semiconductor laser 1a, which can be independently driven and modulated.
The structure is such that 1b and 1c are arranged in a line.

As shown in FIG. 12, the semiconductor laser array 1 oscillates the beams emitted from the three semiconductor lasers 1a, 1b, and 1c so as to have the maximum intensity distribution in the normal direction perpendicular to the end faces thereof. When collimated by the collimator lens 2, only the beam of the semiconductor laser 1b located on the optical axis runs parallel to the optical axis, and the semiconductor lasers 1a, 1a located outside the optical axis.
For b and 1c, they are collimated at a finite angle θ with the optical axis.

The use of such an array of light sources has the following advantages over the case of using only one light source. one. It is fast because it can record and display multiple scan lines simultaneously. two. Therefore, the speed of the rotary polygon mirror or galvano mirror may be slow. three. Further, the semiconductor laser power may be low, which is advantageous for deterioration. For the above reasons, it is very effective to use the array light source.

In order to control the output of the semiconductor laser array,
A photo detector is used. The conventional semiconductor laser array is
Instead of a photodetector for monitoring the light intensity of each light emitting point, one semiconductor laser array has one photodetector (hereinafter referred to as PD).

Generally, the light intensity of the light emitting point of the semiconductor laser is monitored by receiving the light emitted in the direction opposite to the light emitting direction. Therefore, when there is one light emitting point, the light is not emitted from that. I definitely understand.

[0009]

With respect to the above-mentioned points, since the light intensity of each light emitting point of the semiconductor laser array cannot be monitored independently, power control (of the 1-dot multi-value control which influences the halftone reproducibility) Hereinafter, it cannot be called PM). However, pulse width modulation (hereinafter referred to as PWM) is possible, and it is said that up to 8 values can be made for one dot.

Regarding the above-mentioned points, the commercially available semiconductor array has a plurality of light emitting points, but since it has only one PD, it is not possible to separate from which light emitting point the light comes from, and each light emitting point cannot be separated. The light intensity could not be controlled. In addition, although it is considered that the light is guided from each light emitting point to the PD by a waveguide,
Since the size of the PD is larger than that of the semiconductor laser, downsizing is difficult.

It is therefore an object of the present invention to provide an optical device capable of independently monitoring the light intensity of each light emitting point of a semiconductor laser array without increasing the size of the device.

[0012]

In order to achieve the above object, in the present invention, (1). Between the light emitting source of the semiconductor laser array and the collimating optical system, a semi-transparent mirror that splits the light flux from the light emitting source into a direction different from the optical axis of the collimating optical system, and the light flux split from this semi-transparent mirror is connected at a predetermined interval. An image forming optical system for forming an image and a detector for detecting the light intensity of each image forming light from the image forming optical system are provided.

(2). In (1), the semi-transparent mirror may be integrated with the case of the semiconductor laser array, and the case may be provided with an opening for guiding the light flux separated from the semi-transparent mirror.

(3). It is also possible to provide an image forming optical system for forming an image at a predetermined interval on the side opposite to the light emitting portion of the light emitting source of the semiconductor laser array, and a detector for detecting the light intensity of each image forming light from this image forming optical system. it can.

(4). A drive terminal is provided in a direction substantially orthogonal to the light emitting direction of the light emitting source of the semiconductor laser array,
A transparent cover glass may be provided on the light emitting portion side, a member capable of transmitting light and a detector for detecting the light intensity of the emitted light may be provided on the side opposite to the light emitting portion.

(5). In (4), the member capable of transmitting light and the detector for detecting the light intensity of the emitted light may be detachably attached to the case of the semiconductor laser array.

[0017]

The intensity of a part of the output from the semiconductor laser array is detected by the imaging lens for each luminous flux corresponding to each light emitting point of the semiconductor laser array.

[0018]

【Example】

1. Example Corresponding to Claim 1 (See FIG. 1) As shown in FIG.
It is housed in a case indicated by A, and a cover glass 10 is provided on the semiconductor laser emitting portion side of this case.
A semitransparent mirror 11 is provided between the cover glass 10 and the collimator lens 2, and the semitransparent mirror separates the light flux from the semiconductor laser array in a direction different from the optical axis of the collimator lens 2.

The separated luminous flux is divided into three luminous fluxes 13a, 13b, 13c through the imaging lens 12, and the luminous fluxes are divided into photodetecting elements (photodetectors (PD)) 14a, 14b, 14c constituting a detector 14, respectively. An image is formed for each light flux. Since the light beams are detected independently, the light detection elements are arranged at predetermined intervals. A detection signal obtained by this detection is guided to the controller 15 to independently control the light intensity of each light emitting point of the semiconductor laser that constitutes the semiconductor laser array 1.

Here, assuming that the distance between the light emitting points of the semiconductor laser array 1 is LH and the predetermined distance between the light detecting elements is LP, the imaging magnification β by the imaging lens 12 is β = LP / LH. . Also, the focal length of the imaging lens 12 is f,
The distance from the semiconductor laser array 1 to the detector 14 is LL
Then, LL = f × (β + 1) ² / β holds. Therefore, the smaller the focal length f of the imaging lens 12, the more compact the optical system. By this example,
The light intensity of each light emitting point of the semiconductor laser array is independently monitored. Further, since it can be monitored independently, PM that is one-dot multi-value control can be performed, multi-tone reproduction can be performed, and image quality can be improved.

2. Example Corresponding to Claim 2 (See FIG. 2) As shown in FIG. 2, the cover glass is used also as the semi-transparent mirror 11 between the cover glass 10 and the collimator lens 2 in the example of FIG. Further, the light flux separated by the semi-transparent mirror 11 is guided to the imaging lens 012 and, at the same time, the imaging lens 12 is incorporated in the case 1B. The configuration and operation after the imaging lens 12 are in accordance with the contents described in the first example. In this example, by integrating the semi-transparent mirror 11 and the case 1B of the semiconductor laser array, it is possible to independently monitor the light intensity of each light emitting point of the semiconductor laser array while reducing the number of parts.

3. Example corresponding to claim 3 (see FIG. 3) Normally, when the semiconductor laser has a shape as shown in FIG. 11, light is emitted also on the side opposite to the light emitting direction, and normally this light is used. The laser output of the semiconductor laser is controlled by detecting the light intensity at the light emitting point. Therefore, in this example, the light flux emitted from the rear of the semiconductor laser array 1 is used to guide the light flux 13a, 13b, 13c to the detector 14 by the imaging lens 12. In this example, the light intensity of each light emitting point of the semiconductor laser array can be independently monitored without using a semi-transparent mirror as in the above example. Further, since the light receiving portion is arranged on the opposite side of the light emitting portion, there is no loss in the light amount of the light source and the light source output can be reduced.

4. Example corresponding to claim 4 (Fig. 4) Normally, in the drive terminal 20 of the semiconductor laser, the light detection element is arranged on the side opposite to the light emitting direction, whereas in the present example, the drive terminal 20 is set in the light emitting direction. By arranging in the substantially orthogonal direction, the light flux emitted from the rear of the semiconductor laser array 1 on the side opposite to the light emitting direction is used by the imaging lens 12 to emit the light flux 1.
A cover glass 10 made of a transparent member is provided on the side opposite to the light emitting direction so as to be guided to the detector 14 as 3a, 13b and 13c. The cover glass 10 is provided in the light emitting direction as usual. The configuration and operation after the imaging lens 12 are the same as those described in the first example.

According to this example, the light intensity of each light emitting point of the semiconductor laser array can be independently monitored, or one PD can receive and monitor the light intensity as in the conventional case. Also,
Semiconductor laser array 1 when the optical system for light detection is not used
Laser array 1 using the light flux emitted from the rear of the laser
The eccentricity adjustment (optical axis alignment) of itself becomes easy. If the detection unit is provided on the opposite side of the light emitting unit, light may be blocked by the drive terminals in the optical path or the layout may be burdened.However, by providing the drive terminals in a direction substantially orthogonal to the light emitting direction, the flexibility of layout is improved. Can be increased.

5. Example Corresponding to Claim 5 (See FIGS. 5 to 8) There are cases where it is desired to independently control the light intensity of each light emitting point of the semiconductor laser array, and where there is a case where only the presence or absence of light output from each light emitting point is monitored. This example can cope with these cases. For the former independent control, as shown in FIG. 5, a member 1G to which a cover glass 10 made of a transparent member is attached is provided in a case 1E behind the semiconductor laser array 1 (on the left side in the figure) on the side opposite to the light emitting direction. When it is desired to monitor only the presence or absence of light output from each of the latter light emitting points, as shown in FIG. 6, the member 1F to which the detector 14 having one light receiving portion is attached is adhered to the case 1E.

As a modified example of this example, there are examples shown in FIGS. This is because an opening is formed in the case 1E behind the semiconductor laser array 1 (on the left side in the figure) on the side opposite to the light emitting direction, and the detector 14 (see FIG. 7) or the outside is provided.
The cover glass 10 (see FIG. 8) can be adhered and fixed. Reference numeral 18 indicates an adhesive portion. In this example,
With respect to the semiconductor laser array having the structure of Example 4, the member on the opposite side of the light emitting portion and the detector for detecting the light intensity can be replaced after the eccentricity of the semiconductor laser array is adjusted, so that the assembly and adjustment can be facilitated. .

[0027]

According to the present invention, the light intensity of each light emitting point of the semiconductor laser array can be independently monitored without increasing the size of the device.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optical device for explaining an embodiment of the present invention.

FIG. 2 is a configuration diagram of an optical device for explaining an embodiment of the present invention.

FIG. 3 is a configuration diagram of an optical device for explaining an embodiment of the present invention.

FIG. 4 is a configuration diagram of an optical device for explaining an embodiment of the present invention.

FIG. 5 is a configuration diagram of an optical device for explaining an embodiment of the present invention.

FIG. 6 is a configuration diagram of an optical device for explaining an embodiment of the present invention.

FIG. 7 is a configuration diagram of an optical device illustrating an embodiment of the present invention.

FIG. 8 is a configuration diagram of an optical device for explaining an embodiment of the present invention.

FIG. 9 is an explanatory diagram of a conventional technique.

FIG. 10 is an explanatory diagram of a conventional technique.

FIG. 11 is an explanatory diagram of a semiconductor laser array.

FIG. 12 is an explanatory diagram of a luminous flux emitted from a semiconductor laser array.

[Explanation of symbols]

1 Semiconductor laser array 2 Collimator lens (as collimating optical system) 12 Imaging lens (as imaging optical system) 14 detector

Claims (5)

[Claims] 1. A light source section using a semiconductor laser array in which a plurality of light emitting sources capable of independently modulating light in a direction parallel to a bonding surface are used, and a collimating optical system for collimating a plurality of light beams from the light source section. And an optical device having a deflector for deflecting the light beam from the collimating optical system in a predetermined direction and an optical system for simultaneously imaging and scanning the deflected light beam from the deflector onto a predetermined photosensitive medium. Between the light emitting source and the collimating optical system, a semi-transparent mirror that splits the light beam from the light emitting source into a direction different from the optical axis of the collimating optical system, and a light beam that is split from the semi-transparent mirror to form an image at a predetermined interval. An optical device using a semiconductor laser array, comprising an image optical system and a detector for detecting the light intensity of each image-forming light from the image-forming optical system. 2. An optical device using a semiconductor laser array according to claim 1, wherein a semi-transparent mirror is integrated with a case of the semiconductor laser array, and an opening for guiding a light beam separated from the semi-transparent mirror is provided in the case. . 3. A light source section using a semiconductor laser array in which a plurality of light emitting sources capable of independent light modulation are arranged in a direction parallel to the joint surface, and a collimating optical system for collimating a plurality of light beams from the light source section. And an optical device having a deflector for deflecting the light beam from the collimating optical system in a predetermined direction and an optical system for simultaneously imaging and scanning the deflected light beam from the deflector onto a predetermined photosensitive medium. A semiconductor laser array comprising an image forming optical system for forming an image at a predetermined interval on the side opposite to the light emitting portion of the light emitting source, and a detector for detecting the light intensity of each image forming light from the image forming optical system. Optical device using. 4. A light source section using a semiconductor laser array in which a plurality of light emitting sources capable of independent light modulation are arranged in a direction parallel to a joint surface, and a collimating optical system for collimating a plurality of light beams from the light source section. And an optical device having a deflector for deflecting the light beam from the collimating optical system in a predetermined direction and an optical system for simultaneously imaging and scanning the deflected light beam from the deflector onto a predetermined photosensitive medium. A drive terminal is provided in a direction substantially orthogonal to the light emitting direction of the light emitting source, a transparent cover glass is provided on the light emitting portion side, a member capable of transmitting light on the side opposite to the light emitting portion, and detection for detecting the light intensity of emitted light. An optical device using a semiconductor laser array, each of which is provided with a container. 5. An optical device using a semiconductor laser array according to claim 4, wherein a member capable of transmitting light and a detector for detecting the intensity of emitted light are detachably attached to the case of the semiconductor laser array. .