JPS60172007A - Laser light generator - Google Patents

Abstract

PURPOSE:To maintain the size of the spacing between a semiconductor laser and a collimating lens constant by providing means for controlling the respective supporting members for the semiconductor laser and collimating lens to a constant temp. CONSTITUTION:A semiconductor laser LD1 is supported by a spacer 10 and a flange 12 supporting a lens unit holder 11 is adhered tightly to the spacer 10. A collimating lens Lc is mounted to the inside of the holder 11. A silicone rubber sheet 13 holding a Peltier effect element 15 in sandwich is tightly adhered to the surface on the side opposite from the mounting surface of the spacer 10 and a heat radiating fin 16 is attached to the other silicone rubber sheet 14 in tight contact therewith. The spacer 10 and the flange 12 are manufactured of an Al alloy, etc. having good heat conductivity and a thermistor 17 is attached on the spacer 10 in the position spaced from the element 15. The spacer 10, the laser LD1 and the flange 12 are controlled to a constant temp. with the detection of temp. by the thermistor 17. The trouble in which the spacing between the semiconductor laser and the collimating lens changes owing to the thermal expansion or contraction of the supporting member is thus averted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a laser beam generating device, and more particularly to a laser beam generating device applied to a laser printer.

(Prior Art) A semiconductor laser is known as a laser light source. Semiconductor lasers are smaller, cheaper, and consume less power than laser light sources such as gas lasers, and have the characteristics of being able to linearly modulate the emission intensity by driving current, making them ideal for optical scanning devices. Suitable as a laser light source.

The following is an example of an optical scanning device configured using a semiconductor laser as a light source.

As shown in FIG. 1, the semiconductor laser LD is supported by a mount 1, and is controlled at a constant temperature to ensure performance by a thermistor 2 and a Bertier effect element 3 as a temperature control element. In addition, these members are surrounded by a heat insulating member 4 and thermally isolated. semiconductor laser L
A lens unit 5 containing a collimating lens is supported in front of D.

The collimating lens is provided to convert the diverging light flux from the semiconductor laser into a parallel light flux.In order to increase the coupling efficiency of the coupling lens, the larger the numerical aperture (NA), the more suitable it is. Positioning accuracy of the lens with a shallow depth of focus is required. Generally, it is said that NA'=about 0.3 is sufficient in relation to the depth of focus.

Now, in the conventional technology, the semiconductor laser LD is surrounded by the heat insulating member 4 and the temperature is controlled, but the supporting members 6 and 7 supporting the lens unit 5 are thermally exposed to the outside air. They live in the same environment as they are placed in, and there is no temperature control, so they are directly controlled by the environmental temperature.

Therefore, the support member 6.7 thermally expands (or thermally contracts) due to the temperature change associated with driving this laser beam generator and the optical scanning device using the same, and the change in room temperature, and the semiconductor laser LD. There is a problem in that the distance between the collimating lens and the collimating lens deviates, making it impossible to obtain the required imaging light diameter on the photoreceptor or document.

(Objective) Therefore, an object of the present invention is to provide a laser light generating device that can maintain a constant physical dimension interval between a semiconductor laser and a collimating lens.

According to the above-mentioned object of the present invention, there is provided a laser light generating device including a hot water temperature control means for controlling the respective supporting members of the semiconductor laser and the collimating lens at a constant temperature.

(composition) The configuration of the present invention will be explained below based on one embodiment.

In FIG. 2, the semiconductor laser LD has a spacer 10
Further, a flange 12 supporting a lens unit holder 11 is attached to this spacer 1° in close contact with the lens unit holder 11. Lens unit holder 1
1, a collimating lens Lc is attached.

In the spacer 10, a Beltier effect element 15 is attached to the surface opposite to the mounting surface of the spacer 1o.

The silicone rubber sheets 13 which are sandwiched in a Tee shape are in close contact with each other, and the radiation fins 16 are attached in close contact with the other silicone rubber sheets 14.

In the above configuration, the spacer 10 and the flange 12 are made of a material with good thermal conductivity, such as an aluminum alloy. Vertier effect element 15 on the spacer lo
A thermistor 17 is attached at a position spaced apart from.

A partition wall 18a of a second spacer 18 made of a heat insulating material is interposed between the semiconductor laser LD and the radiation fin 16 to thermally isolate the semiconductor laser LD.

This second spacer 18 also covers a portion of the base v10.

The silicone rubber sheets 13 and 14 have thermally conductive and electrically insulating properties, and function to bring the Beltier effect element 15 into close contact with the spacer 10 and the heat radiation fins 16 to improve heat conduction.

Based on the temperature information detected by the thermistor 17,
Spacer 10 and semiconductor laser LD1 are at constant temperature side (toward)
Further, this temperature control effect extends to the flange 12 supporting the lens unit holder 11, and its temperature is also controlled to the same constant temperature as the spacer 10.

That is, the temperature control effect of the Beltier effect element 15 also extends to the supporting member of the collimating lens Lc, so as in the prior art, the distance between the semiconductor laser and the collimating lens changes depending on the thermal expansion (contraction) of the supporting member. Harmful effects can be avoided.

Furthermore, in this example, supporting members such as the spacer 10 and the flange 12 are also surrounded by a heat insulating member in order to make the function of the Beltier effect element 15 more effective and to improve the efficiency of drive energy.

The means for doing so will be explained below.

The spacer 10 is surrounded by a cylindrical first heat insulating member 19 and a second heat insulating member 20 in close contact with the first heat insulating member 19. Further, the seven runci 12 is surrounded by a second flange 21 made of a heat insulating material such as synthetic resin. This second flange 21
However, the second heat insulating part 20 is attached like a cap.

Incidentally, an opening must be formed in the second flange 21 in order to ensure an optical path for the laser beam, but this is done.

When a mirror is used, it has a function of rotating the polarization plane of the laser beam by 90 degrees in accordance with the lattice direction of the hologram in order to increase the diffraction efficiency by the hologram.

1 This hundred wavelength plate 22 is attached to the holder 23 by adhesive, and is also attached to the second flange 21.

Thus, the spacer 10, which is subject to temperature control. Since the flange 12, semiconductor laser LD, etc. are surrounded by a heat insulating member, they are not easily affected by temperature changes from the outside, and the load on the Bertier effect element 15 is reduced, improving constant temperature maintenance performance.

FIG. 3 specifically shows the configuration shown in FIG. 2.

The structure will be explained below according to the assembly procedure.

In the figure, the lens unit holder 11 includes a washer 24,
It is screwed onto the cylindrical portion 12a of the flange 12 via a wave washer 25, washer 26, etc. for preventing back push.

Here, the notch 11a formed in the lens unit holder 11 is used for holding a wrench when performing the above-mentioned screwing, and is also used for focus positioning.

In this way, after attaching the lens unit holder 11,
The semiconductor laser LD is in the engagement hole 10a1 of the spacer 10.
The presser plate 29 is engaged with and abuts on the stepped seat surface.
It is tightened with screws 30° and 31 so that it can be held down from the rear. At that time, the notch 32 of the semiconductor laser II)
is engaged with a pin-shaped member protruding from the inside of the engagement hole 29a of the semiconductor laser LD formed on the holding plate 29, thereby specifying the direction of the joint surface of the semiconductor laser. Further, a spacer 33 designed for heat insulation is engaged with the cylindrical portion in which the engagement hole 29a is formed, and a printed circuit board 34 for driving a semiconductor laser is attached from the back thereof. Reference numeral 34a indicates a terminal. The thermistor 17 is screwed to the moss spacer lO.

In this way, the spacer 10 to which the semiconductor laser LD and the like are attached is attached to the screw holes 12az+12bz of the shift pusher 12 using two attachment screws. One of these screws is indicated by reference numeral 35. This installation is sometimes done through hole 10b.

Engage the tool with 10c#i and turn on the semiconductor laser LD.

Adjustments are also made to align the light emitting point with the optical axis of the collimating lens. Specifically, the spacer 10 is connected to the flange 12
This is done by slightly moving within the plane.

In this way, the light emitting point is aligned with the optical axis and rotated so that the emitted light becomes parallel.

Then, the claws 23a of the holder 23 are inserted through the notches 21a and 21b formed in the opening of the second flange 21.
," 23b, and then rotate the holder 23 to attach the holder 23. Note that the bolt
Next, the second heat insulating member 2o and the first heat insulating member 19 stacked thereon are pressed against the flange 12, and further, the second spacer 18 is pressed against the spacer 10, and then Seat surface 10a of spacer 1o
K silicon rubber sheet 13, Bertier effect element 15,
1) Rubber Seat) While pressing in the order of 14, insert the three holes 16e, 16f, 16g of the radiation fin 16.
Further, the hole in the first heat insulating member 19 and the three holes in the second spacer 18 are passed through the hole through the hole in the first heat insulating member 19 and the three holes in the second spacer 18, and the screws are tightened into the three screw holes 10e, 10f, and 10g in the spacer 1o. One of the screws mentioned above is designated by the reference numeral 35.

In this way, the integrated laser generator is attached to the main body of the optical scanning device. This installation is done through two holes 16a and 16b formed in the radiation fin 16.
'! This is done via a'. By the way, if one of the screws is designated by the reference numeral 36, this screw 36 passes through the hole 16a and passes through the side notch 19a of the first heat insulating member 19.
It penetrates through the hole 2oa of the heat insulating member 2o, and furthermore, the flange 1
The 27th run 2
No. 1 hole 21d'la: is passed through and screwed into the main body side plate of the optical scanning device (not shown). .

In the above explanation, for the sake of organization, the members made of heat insulating materials are enumerated once more: the housing body 21' made of synthetic resin material, and the pushbutton made of synthetic resin material.
12al, first FF thermal member 1 made of polyurethane foam
9. In this example, the second heat insulating member 2o and the synthetic resin are, for example, a collimator lens with a focal length of g mm, an OF lens with a focal length of 300 mm, and the necessary optical system and scanner to form a scanning device. When configured, the relationship between the change in the beam diameter on the scanned surface due to the change in the distance between the collimating lens and the semiconductor laser is as shown in Fig. 4, and in the sub-scanning direction as shown by the solid line. The amount of change in the scanning direction of the scanned surface perpendicular to the scanning direction by the scanning means is almost negligible, but in the main scanning direction (scanning direction by the scanning means) shown by the reef line, the image This causes a non-negligible change in the diameter of the luminous flux.

Support member? Aluminum (linear expansion coefficient = 23.6X10
-6 art/cm deg) and the maximum expected temperature change is 35°C, the amount of change in the semiconductor 1 noser with respect to the collimating lens will be 8 μm if no temperature control means are applied. The amount of change in the diameter of the light beam on the surface to be scanned corresponding to this exceeds the range that can be used in practical applications for image formation.

However, when implementing the present invention, temperature control is ±1°C.
The amount of relative change in the position of the semiconductor laser can be kept within 0.47 μm, which does not cause any problem in image formation.

(Effect) In the present invention, the temperature and pressure control effect by the thermistor, the Bertier effect element, the radiation fins, etc. significantly affects the supporting member of the semiconductor laser and the collimating lens, so the temperature of the supporting member is controlled to be constant. This is advantageous because thermal expansion (contraction) does not affect the distance between the laser and the collimating lens.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a laser beam generator according to the prior art;
FIG. 2 is a cross-sectional view of the laser beam generator according to the present invention, FIG. 3 is an exploded perspective view of the laser beam generator according to the present invention,
FIG. 4 is a graph illustrating the amount of change in the beam diameter on the scanned surface due to positional deviation of the semiconductor laser. 10... Spacer, 12... Flange, 15...
Beltier effect element, 16...radiating fin, 17...
thermistor.

Claims (1)

[Scope of Claims] A semiconductor laser as a light source, a collimating lens that converts a diverging light beam from the semiconductor laser into a parallel light beam, and mechanically holding the semiconductor laser and collimating lens in a predetermined imaging position. What is claimed is: 1. A laser beam generation device having a support member that is characterized in that the device includes a temperature control means for maintaining the support member at a constant temperature.