JPH04104271A - Light source device - Google Patents

Abstract

PURPOSE:To make variation of focal position due to change in temperature smaller than allowable limit by forming a retaining member retaining a semiconductor laser from polycarbonate resin with a fixed portion of carbon fiber combined. CONSTITUTION:The base 2 is formed of thermoplastic polycarbonate resin containing 20 to 30% of carbon fiber, for example, a hole with levels 2a which is an engagement part of the semiconductor laser 1 is formed on that base 2, the semiconductor laser 1 consisting of a body part 1a and a flange part 1b is forcibly fed and fixed to this hole with levels 2a, and the retaining member of the semiconductor laser is constituted by the base 2. Then, the base 2 which has a printed substrate 6 integrated to it can be fixed to the flange 8, an outer periphery part of a lens barrel 12 of a collimater lens 11 consisting of an aspherical lens, which is a single lens, is inserted to a cylindrical projection 8b of the flange 8, and the lens barrel 12 is fixed to the flange 8. Thus, the variation of the focal position due to the temperature change of the collimater lens can be suppressed to about 0.5mm, which is the allowable limit.

Description

[Detailed description of the invention] [Industrial application field] This invention is a laser printer and a facsimile machine.

The present invention relates to a light source device in an optical scanning device used for optical writing in a copying machine or the like.

[Prior Art] As a conventional semiconductor laser unit used in this type of light source device, the one shown in FIG. 5 is known.

A semiconductor laser 1 of this light source device has a body part 1a and a flange part 1b.The body part 1a is fitted into a through hole 2a of a base 2, and the flange part 1b is attached to the base 2 by a holding plate 3 having a through hole 3a. Both are fixed by a set screw 4 in the pressed state. A printed circuit board 6 is attached to the base 2 with a set screw 7 at a predetermined distance via a spacer 5, and a plurality of lead wires 1c of the semiconductor laser 1 are inserted into a plurality of through holes 6a provided in the printed circuit board 6. It is soldered and connected to circuits formed on both sides of the printed circuit board 6.

The base 2 is fixed to the flange 8 with a set screw 9, a screw hole 8a is provided in the flange 8, and a second screw hole 8a is provided in the flange 8.
the lens barrel 1 of the collimator lens 11 via the washer 10.
2 is screwed on. Further, a flange cover 13 is fitted onto the cylindrical protrusion 8b of the flange 8, a cylindrical protrusion 13a surrounding the lens barrel 12 is provided on the flange cover 13, and an aperture frame 14 having an aperture 14a is fixed at the tip thereof. do.

Further, the flange 8 is fixed to the housing 15 via a flange cover 13 with set screws 16.

The base 2, which is a holding member that holds the semiconductor laser 1, is made of die-cast material such as aluminum or zinc, or glass fiber reinforced polycarbonate resin.

In addition, the collimator lens 11 is conventionally designed to have a plurality of lenses made of a combination of different materials to correct wavefront aberration so that the focal position does not change even if the wavelength of the semiconductor laser 1 changes. However, as aspherical lenses have come into practical use in recent years, they are often constructed from a single lens.

[Problems to be Solved by the Invention] However, such conventional light source devices have the following problems.

That is, semiconductor lasers generally have the characteristic that the wavelength λ shifts depending on the temperature T'C, as shown in FIG.
There is a wavelength variation of 11 to 15 mm for a temperature change of 50''C.

In addition, the focal position variation due to the wavelength λ of a single lens is generally 0.3 to 0.5 μm/, although it depends on the material.
nm, and at a temperature change of 50°C, the maximum is 7.5 μm.
becomes.

The distance E is the same in the case of a SELFOC lens made of a single material in which the refractive index decreases from the center toward the outside.

Figure 7 shows that when a single aspherical lens is used as the collimator lens, the base that holds the semiconductor laser is made of aluminum die-casting (a), glass fiber 30% λ polycarbonate resin (b), and unreinforced polycarbonate resin (
This shows the results of actual measurements of the amount of variation X in the image formation position on the photoreceptor due to changes in the environmental temperature T'C when using c). ) is -1,
3mm.

It can be seen that (c) fluctuates by -3.3 mm.

Figure 8 shows the movement of the beam shape as the imaging position changes;
It shows the changing state of the spot shape on the photoreceptor P and the energy distribution curve near the imaging point. Here, a wave is established where the beam waist radius is a, the radius of the beam spot is x, and the amount of fluctuation of the imaging point is x.

When the imaging position changes in this way, the spot diameter on the photoreceptor P changes, resulting in deterioration of image quality. Various factors can be considered for image formation position fluctuations, such as the accuracy of the focal length of the imaging lens, the surface accuracy of the photoreceptor, and the positional errors of optical elements, but the above-mentioned fluctuations due to temperature cannot be ignored. It is considered to be one of the

Now, in the above relational expression, when a = 40 μm and λ = 780 nm, and if the allowable change amount of the beam spot diameter is 5%, then the following equation is obtained.

Therefore, if the value of the amount of variation X of the imaging point is the amount of variation due to the shape error of the optical element, the amount of variation due to the placement error of the optical element, the amount of variation due to the adjustment accuracy of the light source unit, and the amount of variation due to the above-mentioned temperature change, Assuming that they are evenly distributed, the permissible limit of variation for each is 0.5 m.
m. However, in reality, the amount of variation due to the material of the holding member of a conventional semiconductor laser far exceeds this amount, and the accuracy of the other three elements is affected by this variation.

The present invention has been made in view of the above points, and it is an object of the present invention to provide an optical device that can reduce fluctuations in the imaging position due to temperature changes to below permissible limits.

[Means for Solving Section V] In order to achieve the above object, the present invention provides an optical scanning system comprising a semiconductor laser as a light source and a collimator lens that converts a divergent light beam from the semiconductor laser into a substantially parallel light beam. In the light source device of the apparatus, the holding member for holding the semiconductor laser is molded from polycarbonate resin mixed with 20 to 30% carbon fiber.

The collimator lens may be made of a single material, or may be made of a single aspherical lens.

[Function] The light source device according to the present invention uses polycarbonate resin mixed with 20 to 30% carbon fiber as the holding member for the semiconductor laser serving as the light source, so that the collimator lens consisting of a single aspherical lens can be prevented from changing due to temperature changes. It becomes possible to suppress the fluctuation of the imaging position to the permissible limit of about 0.5 mm.

(Example) Hereinafter, the present invention will be described in detail with reference to FIGS. 1 and 2 of the accompanying drawings, but first, the optical system of a laser printer using the light source device according to the present invention will be briefly explained with reference to FIG. 3. Explain.

The beam emitted from the semiconductor laser 1 is modulated by a recording signal, and the scanning beam deflected by the 0-rotation polyhedron 30 is shaped by the aperture 14a of the aperture frame 14 and enters the rotation polyhedron 30. 32. Photoreceptor 34 via cylindrical lens 33
Images are sequentially formed into spots on the top.

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is an exploded perspective view thereof, and parts corresponding to those in FIG. 5 are designated by the same reference numerals.

In this embodiment, the base 2 is made of, for example, 20 to 30 carbon fibers.
% thermoplastic polycarbonate resin (hereinafter referred to as "PC")
), and a semiconductor laser 1 is attached to the base 2.
A stepped through hole 2a is formed which is a fitting part of the stepped through hole 2a.
A semiconductor laser 1 consisting of a body portion 1a and a flange portion 1b is press-fitted into the base 2 and constitutes a holding member for the semiconductor laser 1. Two screw holes 2b are provided in this base 2, and two spacer parts 2c are integrally formed, and a tapered guide pin 2d is provided at the tip of each spacer part 2c.
to protrude.

On the other hand, a printed circuit board 6 with many components mounted on both the front and back sides
A through hole 6a for a plurality of lead ICs of the semiconductor laser 1 and two guide holes 6C are provided in the guide hole 6c.
By fitting and attaching the guide bin 2d,
The lead wire 1c of the semiconductor laser 1 is made to be able to pass through the through hole 6a. In this state, the printed circuit board 6 is attached to the base 2 by melting the guide bottle 2d using heat or ultrasonic waves and crushing the tip into the state shown by the imaginary line in FIG.
can be integrally fixed to the lead wire 1c.
A semiconductor laser drive circuit is formed by soldering to the printed surface of the printed circuit board 6.

The base 2 integrated with the printed circuit board 6 can be fixed to the flange 8 by inserting the set screw 9 through the mounting hole 8C of the flange 8 and screwing into the screw hole 2b. The outer periphery of the lens barrel 12 of the collimator lens 11 made of a single aspherical lens is fitted into the cylindrical protrusion 8b, and adhesive is poured into the notch 8d provided in the flange 8 to attach the lens barrel 12 to the flange 8. be fixed to.

Finally, the aperture frame 14 having the aperture 14a is fitted onto the outer periphery of the lens barrel 12, and the protrusion 14b shown in FIG. 2 is inserted into the notch 8d of the flange 8 and fixed.

Note that the collimator lens 11 described above may be a Selfoc lens made of a single material instead of a single aspherical lens.

In this way, the base 2, which is a holding member for the semiconductor laser 1,
By molding with PC containing 20 to 30% carbon fiber, fluctuations in the imaging position due to temperature changes of the collimator lens 11 can be suppressed to a smaller extent than with conventional aluminum die casting or glass fiber-filled PC.

Figure 4 shows each environmental temperature T' when PC containing 20% carbon fiber (d) and PC containing 30% carbon fiber (e) are used for the base 2.
The actual measured value of the amount of variation X in the imaging position of the single-element aspherical collimator lens 11 at C was determined for each material (A) shown in FIG.
, (b), and (c) in comparison with the base cases.

As a result of actual measurements, carbon fiber 20% PC (:
), the amount of variation X is -0.5mm, carbon fiber 30%
In the case of PC (e), the value is +0.5 mm, and although not shown, it has been found that almost the same value is obtained when the amount of carbon fiber mixed is in between.

As mentioned above, the value of the variation amount of 0.5 mm is within the permissible limit for the variation amount of the image forming position, and if other conditions are kept within the permissible limits, the photoreceptor Good image quality can be obtained by making the spot diameter sufficiently small.

Furthermore, according to this embodiment, in addition to the above effects, the following effects can also be expected.

That is, by press-fitting and fixing the semiconductor laser l into the base 2, the guide bin 2 formed integrally with the base 2
The positional relationship with d can be set accurately. Therefore, by fitting this guide bin 2d into the guide hole 6c of the printed circuit board 6, the positional relationship between the printed circuit board 6 and the semiconductor laser 1 becomes accurate, and the lead wire 1c of the semiconductor laser 1 is connected to the through hole of the printed circuit board 6. 6a can be easily inserted.

At the same time, since no member for fixing the semiconductor laser is interposed between the printed circuit board 6 and the base 2, the surface 6b of the printed circuit board on the semiconductor laser side can be effectively used.
It becomes possible to increase component mounting density, and it is also possible to simplify the assembly process and reduce production costs.

Furthermore, since the distance between the printed circuit board 6 and the base 2 can be reduced, it is extremely effective in downsizing the device.

Furthermore, the contact area between the semiconductor laser 1 and the base 2 is increased, improving thermal conductivity, and the effect of suppressing temperature rise due to self-heating of the semiconductor laser can be expected.

[Effects of the Invention] As described above, in the light source device according to this invention, since the semiconductor holding member is molded from PC containing 20 to 30% carbon fiber, the amount of variation in the imaging position of the collimator lens due to changes in environmental temperature is reduced. It is possible to keep the performance of the optical scanning device good at all times by keeping it within the permissible limit.

Furthermore, by changing the semiconductor holding member to a resin mold instead of the conventional metal die-casting, production costs can be reduced.

In the above light source device, if the collimator lens is made of a single material, the molding process can be simplified and it can be supplied at low cost.Furthermore, if the collimator lens is made of a single aspherical lens, By doing so, it becomes possible to improve the performance to the same level as conventional lenses with multiple configurations with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is an exploded perspective view thereof, FIG. 3 is a configuration and optical path diagram showing the optical system of a laser printer using the light source device according to the present invention, and FIG. The figure is a diagram showing the relationship between the temperature change and the amount of variation in the imaging position in this invention in comparison with the conventional one, FIG. 5 is a cross-sectional view illustrating a conventional semiconductor laser device, and FIG. 6 is the temperature of the semiconductor laser. Figure 7 is a line showing the relationship between temperature change and imaging position variation for each material of a conventional semiconductor laser holding member using a single aspherical collimator lens. FIG. 8 is an explanatory diagram showing the movement state of the beam shape corresponding to the change in the imaging position, the change state of the spot shape on the photoreceptor, and the state of its energy distribution. ■...Semiconductor laser 1c...Lead wire 2
...Base (supporting member) 2a...Through hole (fitting part) 2d...Guide bin 6...Printed circuit board 6c...Guide hole 8...Flange 1
1...Collimator lens 12 lens barrel 4...Aperture frame 3o...Rotating polyhedron 31...F
θ lens 32...Reflector 33...Cylindrical lens 34...Photoconductor

Claims (1)

[Scope of Claims] 1. A holding member that holds the semiconductor laser in a light source device in an optical scanning device that includes a semiconductor laser as a light source and a collimator lens that converts a divergent light beam from the semiconductor laser into a substantially parallel light beam. , carbon fiber 20
A light source device characterized in that it is molded from a polycarbonate resin mixed with ~30%. 2. The light source device according to claim 1, wherein the collimator lens is made of a single material. 3. The light source device according to claim 1, wherein the collimator lens consists of one aspherical lens.