JPH0582906A - Ld light source unit - Google Patents

Abstract

PURPOSE:To provide an LD light source unit for realizing high density, high speed optical scanning with high optical efficiency. CONSTITUTION:Semiconductor lasers 11A, 11B are mounted, respectively, on the surface and the rear of a planar support 12 so that the junction face thereof will be substantially in parallel with the surface and the rear of the support 12, and the semiconductor lasers 11A, 11B are contained in one package (comprising a stem 16 and a cap (not shown)) and can be driven independently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LD light source and an LD light source device, and more particularly to an LD light source having two LDs and the L light source.
The present invention relates to an LD light source device that uses a D light source.

[0002]

2. Description of the Related Art An optical scanning device using an "LD" or a semiconductor laser as a scanning light source is well known. As a kind of such an optical scanning device, a system in which a plurality of LDs are used as a light source to optically scan a plurality of lines at the same time has been proposed (for example, Japanese Patent Laid-Open Nos. 64-10805 and 64-10805).
-10806 publication). When such an optical scanning system is referred to as a "multiple light source system", the multiple light source system has the following advantages.

That is, since a plurality of lines can be scanned at one time, the optical scanning can be efficiently performed without increasing the speed of the optical deflection by the optical deflector such as the rotating polygon mirror.
Therefore, the optical scanning can be performed relatively slowly,
It is not necessary to increase the LD emission intensity required for optical scanning so much, and therefore the life of the light source can be extended.

On the other hand, however, the multiple light source system has the following problems. That is, when a plurality of lines are optically scanned at one time by using a light source in which a plurality of LDs are arranged, the pitch width of the scanning lines, that is, the "scanning line interval" is set to the arrangement pitch of the LDs in the sub scanning corresponding direction: d. , And the imaging magnification in the sub-scanning corresponding direction of the optical system between the light source and the surface to be scanned: βs. In a general optical apparatus, the magnification is βs> 1.

On the other hand, as a method of arranging a plurality of LDs at a high density, a method of forming a monolithic whole is well known, but in this case, the interval between adjacent LDs is 10 as well.
The limit is about 0 μm, and LDs with a finer pitch
Is difficult to arrange. Thus, even when a plurality of LDs are arranged closest to each other, considering that the imaging magnification βs is larger than 1, the scanning line pitch is 100 μm or more, and high-density optical scanning such as 400 dpi is performed. It cannot be realized.

As a direction for effectively solving this problem, "the light source is tilted by a finite angle: θ with respect to the main scanning corresponding direction".
The method is known. As described above, assuming that the LD array pitch in the light source is: d, if the LD array direction is tilted by an angle of θ with respect to the main scanning corresponding direction, the LD array interval in the sub scanning corresponding direction is (d · sin θ). Therefore,
If the angle: θ is made small, the LD array interval in the sub-scanning corresponding direction can be made small, and high-density optical scanning becomes possible. However, in this case, the following problems occur.

That is, generally, in an optical scanning device using an LD as a light source, in order to make the shape of a light spot formed on a surface to be scanned into a desired shape, an aperture having a long rectangular opening in the main scanning corresponding direction is used. The light flux is limited (beam shaping). On the other hand, as is well known, the far field pattern of the light flux emitted from the LD is elliptical,
In order to utilize the energy of light from the light source as effectively as possible for optical scanning, it is desirable that the direction of the long axis in the far field pattern corresponds to the longitudinal direction of the rectangular opening in the aperture (corresponding to the main scanning direction). However, when a plurality of LDs are arranged monolithically, the long axis direction in the far-field pattern of each LD is a direction orthogonal to the LD arrangement direction. When an attempt is made to achieve high-density optical scanning by tilting at an angle, the long-axis direction of the far-field pattern of the radiated light flux from each LD becomes substantially parallel to the sub-scanning corresponding direction (the lateral direction of the rectangular aperture of the aperture). The light utilization efficiency of each LD for scanning is reduced. If such a decrease in light utilization efficiency occurs, "the LD light emission intensity required for optical scanning does not need to be increased so much, and the life of the light source can be extended."
That is, the advantage of the multiple light source method cannot be effectively utilized.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and is a novel L which enables high-density optical scanning while taking advantage of the multiple light source system.
An object is to provide a D light source and an LD light source device.

[0009]

According to a first aspect of the present invention, there is provided an LD light source, wherein "one LD is provided on each of the front and back surfaces of a flat plate-shaped support, and the bonding surface thereof is substantially parallel to the front and back surfaces of the support. It is arranged and provided so that each LD can be independently driven ”.

In the package of the LD light source according to claim 1, "two photodiodes for individually receiving the light flux emitted backward from the LD for each LD" can be provided (claim 2). Alternatively, it is possible to provide a "single photodiode that receives the light beam emitted backward from the LD in common to the two LDs" (claim 3).

The LD light source according to any one of claims 1 to 3 can be combined with a collimating optical system for collimating the luminous flux from these LD light sources to form an LD light source device (claims 4 and 5).

According to a fourth aspect of the LD light source device, "the LD light source and a collimating optical system for collimating the light from the LD light source are integrated with each other". The LD light source is the LD light source according to claim 1, 2 or 3, and the arrangement position of the LD light source device can be adjusted around the optical axis of the collimating optical system.

An LD light source device according to a fifth aspect has an "LD light source and a collimating optical system for collimating light from the LD light source", and the LD light source device is the LD light source device according to the first, second or third aspect. Is. In the LD light source device according to claim 5, the LD light source can be fitted into the collimating optical system,
It is rotatable about its optical axis with respect to the collimating optical system.

[0014]

As described above, in the LD light source of the present invention, two LDs are provided one on each of the front and back sides of the flat plate-like support, and the bonding surface of each LD is substantially on the front and back surfaces of the support. Since they are parallel, the joint surfaces are also substantially parallel. Therefore, when the array direction of the two LDs is tilted by a small angle θ with respect to the main scanning corresponding direction to reduce the LD array interval in the sub scanning corresponding direction, the bonding surface of each LD becomes substantially parallel to the sub scanning corresponding direction. Becomes
The long-axis direction of the far-field pattern of each emitted light beam is substantially parallel to the main scanning corresponding direction.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment shown in FIG.
Reference numeral 10B denotes a main body portion of D, and a submount portion. The main body portion 10A and the submount portion 10B have one LD
11A. The LD 11A is loaded on the surface side of the flat plate-shaped support 12. The support 12 is integral with the stem 16 and stands upright from the surface of the stem 16.

On the back surface side of the support 12, the other LD 1 composed of a main body portion 10C and a submount portion 10D.
1B is loaded. The boundary between the main body 10A and the submount 10B, the main body 10C and the submount 10
Boundary portions of D form joining surfaces of the LDs 11A and 11B, respectively, and these are substantially parallel to the front and back surfaces of the support 12. The stem 16 has electrodes 18A, 18B, 18C, 1
8D is planted, and the main bodies 10A and 10C are connected to the electrodes 18A and 18B, respectively. These electrodes 18A,
18B, 18C and 18D penetrate the stem 16 and form a lead portion on the back side of the stem 16. The support 12 is a counter electrode for the electrodes 18A and 18B.

The stem 16 is also provided with two photodiodes 14A and 14B. The photodiode 14A is arranged so as to be able to receive the light emitted from the LD 11A rearward, that is, to the side of the stem 16, and outputs a signal corresponding to the amount of received light via the electrode 18C. The photodiode 14B is arranged so as to be able to receive the light emitted rearward from the LD 11A, and outputs a signal corresponding to the amount of received light via the electrode 18D.

The LD light source shown in FIG. 1 is a conventional LD.
As with the light source, a "cap with a window glass (not shown)" is put on and the inside is sealed. The stem 16 and a cap (not shown) form a package.

When performing high-density optical scanning, as shown in FIG. 5, the arrangement direction L of the LDs 11A and 11B is tilted with respect to the main scanning corresponding direction LP by a small angle: θ, and the sub scanning corresponding direction (FIG. 5). Then, the interval between the light emitting portions in the main scanning corresponding direction LP is set to be small. Since the angle: θ is small, the long-axis directions of the far-field patterns FPA and FPB of the light fluxes from the LDs 11A and 11B are close to parallel to the main scanning corresponding direction LP, and the beam is shaped with an aperture having a long rectangular opening in the main scanning corresponding direction. Even if the above is performed, high light utilization efficiency can be secured.

At the time of optical scanning, the light emitted backward from the LDs 11A and 11B is respectively reflected by the photodiode 1.
4A and 14B, and by feeding back to the LDs 11A and 11B via the drive circuit 20 as shown in FIG. 2, for example, the light intensity during pulse width modulation and the stepwise intensity level during power modulation are accurately measured. Can be controlled.

FIG. 3 schematically shows another embodiment of the main part. In order to avoid complication, the same reference numerals as those in FIG. 1 are used for those which are not considered to be confused. In the figure, a flat plate-shaped support body denoted by reference numeral 12A is an L-shaped plane shape and stands upright from the stem 16 in a hook shape, and a pair of LDs 11A and 11B are provided on the support body 12 at a portion apart from the stem surface.
It is formed on the front and back of A. The photodiode indicated by the reference numeral 14 is designed to receive light emitted from the LDs 11A and 11B to the rear of the LDs 11A and 11B.
It is provided in common.

In the case of this embodiment, as shown in FIG. 4, the photodiode 14, the drive circuit 20, and the LDs 11A and 11 are used.
A feedback circuit is formed by B and the LDs 11A and 11B are sequentially made to emit light outside the optical scanning region to stabilize the light intensity during pulse width modulation in the optical scanning region. Of course, in both the embodiments of FIGS. 1 and 3, the LDs 11A and 11B are driven independently during optical scanning.

FIG. 6 is an exploded perspective view showing one embodiment of the LD light source device according to the present invention. The LD light source indicated by reference numeral 1 is
For example, the LD light source as described with reference to FIGS. 1 and 3 is integrated with a collimating optical system indicated by reference numeral 2 and constitutes an LD light source device together with the collimating optical system 2. The base 2B holding the collimating lens 2A has a curved long hole 2
a and 2b are provided, and the LD light source device is fixed to the immovable member 3 by passing the screws 4a and 4b through the curved elongated holes 2a and 2b. With the screws 4a and 4b slightly loosened,
The entire LD light source device can be rotated around the optical axis of the collimating lens 2A within the allowable limit of the curved elongated holes 2a and 2b. Due to this rotation, as described with reference to FIG.
The angle: θ can be changed, and the pitch of the scanning lines can be adjusted / changed according to the pixel density.

FIG. 7 shows an LD light source device according to an embodiment of the present invention. The LD light source indicated by reference numeral 1'is the same as that of the embodiment of FIG. 6, for example, the LD light source described with reference to FIGS. 1 and 3, and as shown in FIG. You can insert and remove it in the direction of the arrow. L
The D light source 1'is slidably rotatable while fitted in the collimating optical system 2 ', but as shown in FIG. 7 (b),
Crabs 1a are formed on the peripheral portion of the package stem, and these claws 1a are the base 2 of the collimating optical system.
It engages with the engaging portion 2a formed on B '. This engagement limits the rotation area around the optical axis of the collimating lens 2A of the LD light source 1. By rotating the LD light source 1 ′ with respect to the base 2B ′, the angle θ described with reference to FIG. 5 can be changed, and the pitch of the scanning lines can be adjusted / changed according to the pixel density. It will be possible.

In each of the embodiments of the LD light source described above, the temperature control as proposed for the conventional LD light source can be implemented. For this purpose, for example, the stem and the support body are integrally formed, and the support body is used as a “heat sink”, the temperature of the stem portion is detected outside the package, and according to the detection result, for example, a Peltier element or the like is known. Temperature control may be performed by a temperature control method. By performing the temperature control in this way, it is possible to prevent mode hopping and the like.

[0026]

As described above, according to the present invention, a novel LD light source and LD light source device can be provided. Claim 1
In the LD light source No. 3, the arrangement direction of the two LDs is arranged at a slight angle with respect to the main scanning corresponding direction, and high density optical scanning with high light utilization efficiency can be performed. Further, claims 4 and 5
In the above LD light source device, the pitch of the scanning lines can be easily adjusted / changed according to the pixel.

[Brief description of drawings]

FIG. 1 is a diagram showing only an essential part of one embodiment of the present invention.

FIG. 2 is a diagram illustrating drive control of an LD in the embodiment of FIG.

FIG. 3 is a diagram showing only a main part of another embodiment.

FIG. 4 is a diagram for explaining drive control of an LD in the embodiment of FIG.

FIG. 5 is a diagram illustrating a characteristic part of the present invention.

FIG. 6 is an exploded perspective view illustrating an embodiment of the apparatus of claim 4;

FIG. 7 is a diagram for explaining an embodiment of the device of claim 5;

[Explanation of symbols]

 11A, 11B LD 12 support 16 stem

Claims (5)

[Claims] 1. A flat support member, one on each of the front and back surfaces,
An LD light source, wherein the LDs are mounted in the same package by arranging the LDs so that their bonding surfaces are substantially parallel to the front and back surfaces of the support, and each of the LDs can be independently driven. 2. The LD light source according to claim 1, wherein the package has two photodiodes for individually receiving the light flux emitted backward from the LD for each LD. 3. The LD light source according to claim 1, wherein the package has a single photodiode for receiving the light beam emitted rearward from the LD in common to the two LDs. 4. An LD light source and a collimating optical system for collimating the light from the LD light source are integrated, and the disposition state is adjustable around the optical axis of the collimating optical system. Is an LD light source according to claim 1, 2 or 3, and is an LD light source device. 5. An LD light source and a collimating optical system for collimating the light from the LD light source, wherein the LD light source is the LD light source according to claim 1, 2 or 3, and is fitted to the collimating optical system. An LD light source device, which is capable of rotating with respect to a collimating optical system around its optical axis.