JPH01145611A - Laser unit - Google Patents

Abstract

PURPOSE:To adsorb the quantity of variation of a gap and to obtain a high- accuracy beam shape regardless of temperature variation by using a resin part formed by adding a filler to a resin material as part of an assembly member, and setting a coefficient of linear expansion as a property value optionally. CONSTITUTION:The laser unit 1 has a semiconductor laser chip 3 and a collimator lens 4 assembled in one body by an assembly member 2 so that a specific gap G is provided. A collimator lens barrel 8, on the other hand, is molded out of a resin material obtained by charging the filler F for varying the coefficient of linear expansion to the resin material. Then the coefficient of linear expansion of the resin part is selected optionally according to the content of the filler charged in the resin material. Consequently, the variation of the gap due to a heat expansion difference among respective constituent parts of the assembly member is absorbed only by varying the coefficient of line expansion of the resin part irrelevantly to the shape, material, etc., of the constitution part other than the resin part of the assembly member.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a laser unit that is applied to, for example, digital copying machines, laser beam printers, CD players, etc. that form images using digital signals.

(Prior Art) Conventionally, as this type of laser unit, there is one shown in FIG. 7, for example. That is, the laser knitting device 0 is constructed by assembling a semiconductor laser chip 102 and a collimator lens 103 together with a predetermined gap G' via an assembling member 101. A can 105 that is a casing including a chip base 104 that holds a chip 102, a first holder 107 that holds the can 105 between a laser substrate 106, and a collimator lens 103.
collimator lens barrel 108 holding the first holder 107
and a second holder 109 that is fixed to and holds the collimator lens barrel 108. Each of these constituent members is made of metal to efficiently dissipate heat generated during laser drive.

On the other hand, when each component of the assembly member 101 thermally expands due to changes in environmental temperature or heat generated by the laser chip 102 during laser driving, the gap G' between the laser chip 102 and the collimator lens 103 changes, causing the collimator lens 103 to change. As a result, in devices such as laser beam printers that use a laser beam to form a latent image on a photoreceptor, the shape of the beam irradiated onto the photoreceptor changes. The desired image could not be obtained. Therefore, conventionally, the assembly member 1
01, the first one thermally expands in the direction of widening the gap G'.
．． The second holders 107 and 109, the chip base 104 that thermally expands in the direction of narrowing the gap G', and the collimator lens barrel 1
Due to the difference in thermal expansion with 08, the gap G due to temperature change
The material, shape, etc. of each component of the assembly member 101 were set so as to absorb the change in .
(See Publication No. 43577).

(Problems to be Solved by the Invention) However, in the case of such prior art, the first. The second holders 107, 109, the collimator lens barrel 108, and the chip base 104 have linear expansion coefficients determined to specific values based on the physical property values of the materials, so that they can absorb changes in the gap G' due to temperature changes. For this purpose, the shape and dimensions must be selected as appropriate. However, since the shape and dimensions of each component are limited by material costs and the space where they are used, the temperature change in the gap G' can only be absorbed to a certain extent, and the allowable temperature change area is narrow. . Therefore, when used in a device that requires high precision, it is necessary to control the temperature of the assembly member using a temperature control means such as a heater or a Peltier element. If such a heater or Peltier element is used, a mounting space is required, leading to an increase in the size of the device and an increase in cost.

The present invention has been made to solve the problems of the prior art described above, and its purpose is to more efficiently absorb changes in the gap between the laser chip and the collimator lens due to temperature changes. Therefore, it is an object of the present invention to provide a laser unit that can set a large allowable temperature change area without using a temperature control means.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a semiconductor laser chip and a collimator lens that are integrally assembled with a predetermined gap therebetween via an assembly member. In the laser unit, a part of the assembly member is made of a resin material, and the linear expansion coefficient of the resin material is changed to a value capable of absorbing a change in the gap caused by a difference in thermal expansion between the constituent parts of the assembly member. It is characterized by being composed of a resin part to which a filler is added.

(Function) The linear expansion coefficient of the resin part can be selected at any value depending on the content of the filler filled in the resin material. Therefore, regardless of the shape, material, etc. of the components other than the resin part of the assembly part, simply changing the coefficient of linear expansion of the resin part absorbs the change in the gap caused by the difference in thermal expansion of each component part of the assembly part. can.

(Embodiment) The present invention will be described below based on illustrated embodiments. In FIGS. 1 to 4 showing a laser unit according to an embodiment of the present invention, l indicates the entire laser unit. There is. In this laser unit 1, a semiconductor laser chip 3 and a collimator lens 4 are assembled together with a predetermined gap G by an assembly member 2.

The assembly member 2 generally includes a first holder 7 that holds a laser element 5 having a laser chip 3 between it and a laser board 6.
, a collimator lens barrel 8 that holds the collimator lens 4 , and a second holder 9 that connects the first holder 7 and the collimator lens barrel 8 .

The laser chip 3 is held at the tip of a base 10 made of a metal with high thermal conductivity such as copper, and is unitized as a laser element 5 housed in a can 11, which is a casing with a hat-shaped cross section.

An opening 11a for emitting a laser beam is provided on the front end surface of the can 11, and this opening 11a is covered with a cover glass flb. On the other hand, the base end of the can 11 has an annular flange portion 11c extending radially outward.
is sticking out.

On the other hand, the first holder 7 is a zinc die-cast plate member with a hole 7a drilled in its center for inserting the can 11 of the laser element 5, and holds the laser element 5 at right angles to the optical axis. The emission angle of the laser beam emitted from the laser chip 3 is positioned in the optical axis direction. That is, the flange portion 1 of the can 11 of the laser element 5 is inserted into the opening of the hole 7a of the first holder 7 on the side of the laser substrate 6.
A reference step portion 12 into which the 1c fits is provided, and this step portion 12
The mounting angle of the laser element 5 is determined by abutting the flange portion lie against the flange portion lie. A spring washer 13 is interposed between the laser element 5 and the laser substrate 6 to press the flange portion IIIC against the step portion 12.

The second holder 9 is a cylindrical member made of zinc cast like the first holder 7, and includes a cylindrical lens barrel holding portion 91 into which the collimator lens barrel 8 is fitted on the inner circumferential side, and A fixing flange portion 92 for fixing to the first holder 7. By moving this second holder 9 in a direction perpendicular to the optical axis, the misalignment between the light emission center axis of the beam emitted from the laser chip 3 and the optical axis of the collimator lens 4 is adjusted.

This first holder 7, second holder 9 and laser board 6
The assembly is done using screws 14 and 15 as shown in FIG. First, the laser board 6 and the first holder 7 are fastened together by screwing the screws 14 into the first screw holes 14a provided in the first holder 7 from the laser board 6 side. On the other hand, by screwing the screw 15 into the screw hole 15a provided in the second holder 9 from the laser board 6 side through the insertion hole 15b provided separately from the first screw hole 14a of the first holder 7, the second The holder 9 is tightened and fixed to the first holder 7. Here, the axis misalignment can be adjusted by adjusting the gap between the insertion hole 15b provided in the first holder 7 and the screw 15. Furthermore, this laser chip 1 is assembled by tightening and fixing it to the mounting member 18 from the laser board 6 side using screws 17.

On the other hand, the collimator lens barrel 8 is molded from a resin material filled with a filler F for changing the coefficient of linear expansion, and constitutes the resin part of the present invention. The collimator lens barrel 8 is fitted into the lens barrel holding portion 91 of the second holder 9 so as to be slidable in the axial direction. The second holder 9 is adhesively fixed by the poured adhesive. The length of the collimator lens barrel 8 is slightly longer than the length of the lens barrel holding part 91, and the inner periphery of the end facing the laser element 5 is a thick lens fixing part 82. A collimator lens 4 is fitted and fixed. The gap G between the collimator lens 4 and the laser chip 3 of the laser element 5 is adjusted by moving the collimator barrel 8 in the axial direction, and after adjustment, the collimator barrel 8 is adhesively fixed to the first holder 7. It is something.

Here, the gap G between the collimator lens 4 and the laser chip 3 changes due to temperature changes. It changes depending on the difference in thermal expansion of the cylinder 8. That is, 1st. The second holder 7.9 thermally expands in a direction that widens the gap G, and the two-chip base 10 and collimator lens barrel 8 thermally expand in a direction that narrows the gap G, and this thermal expansion difference appears as a change in the gap G.

FIG. 2 schematically shows the state of thermal expansion of each component. The change in the gap G is influenced by the reference step 12 of the first holder 7 serving as a reference surface, the dimension 1 from this reference step 12 to the mounting surface of the second holder 9, and the mounting surface of the second holder 9. 2, the length from the adhesive hole 81 of the collimator lens barrel 8 to the laser side end surface (3), and the length from the reference surface of the chip base lO to the laser chip 3 (4). be. The amount of thermal expansion of each part corresponding to a predetermined temperature change is Δit and Δ12.

Δ! ;L3, ΔfLa, the amount of change ΔX in the gap G is Δx=(ΔTachi1+ΔSent2)−(ΔSee3+Δ
It is also expressed as 4).

Then, considering the operating temperature range, the number α3 of linear expansion of the collimator lens barrel 8 as the resin part is set to 6 such that ΔX falls within the depth of focus of the collimator lens 4.
Select sentence 3.

The resin material of the collimator lens barrel 8 is non-quality polyether sulfone (aromatic sulfone resin) (hereinafter referred to as PES).
), crystalline polyphenylene sulfide (hereinafter abbreviated as PPS), and various other resin materials having a large coefficient of linear expansion are used. Among these, non-grade resins such as PES have the advantage of being able to withstand rapid temperature changes and severe usage conditions because their physical properties do not deteriorate much with temperature increases.

On the other hand, as the filler F, one whose linear expansion coefficient is smaller than the thermal expansion coefficient of the resin material is preferably used, and the overall linear expansion coefficient is changed by increasing the content. As the filler, various materials that can change the coefficient of linear expansion of the resin material can be used, such as carbon fiber, glass fiber, and inorganic filler. In this example, PES is used as the resin material and the filler A magnetic filler such as ferrite powder is filled as F to impart magnetism to the collimator barrel 8.

In the laser unit having the above configuration, the first . The linear expansion coefficient α3 is selected so as to absorb the remaining thermal expansion difference obtained by subtracting the thermal expansion amount Δi4 of the chip base lO from the sum of the thermal expansion amount ΔfLr of the second holder 7.9 and Δ12, and this linear expansion The content of filler F is changed so that the coefficient α3 is obtained. In this way, the amount of change ΔX in the gap G with respect to temperature change can be kept within the depth of focus of the collimator lens 4, and the accuracy of the gap G can be ensured. Therefore, a temperature control element such as a Peltier element or a heater for ensuring gear G accuracy is not required.

Here, the first. Experimental data is shown in which the second holder 7.9 is made of zinc cast, the chip base lO is made of copper, and the collimator barrel 8 is made of a composite material of PES and ferrite powder.

Zinc type 1. The linear expansion coefficient of the second holder 7.9 is αl
, α2, the linear expansion coefficient of the collimator barrel 4 is α3, and the linear expansion coefficient of the chip base 10 is α4, then the amount of change ΔX in the gap G is Δx= ((a+ sentence+ +α212) (α31
3+α41a)) Δt. Then, the dimensions of each part are Jll = 1.7 mm, 12 = L3w + s,
13 = f1.8mm.

Sentence a = 2.555m, α1, α2 = 2
．． 74X 10-5 (1/”O), α3 = 3.8
X l 0-5(1/'C).

αa = 1.65X 10-5 (1/'C),
When Δt=40°, Δx = (2,74X (1,7+9.3)−(3
,8X 8.8 + 1.85X 2.55))
1O-5X40=O,0OO037(am)=0.0
37 (ILm).

Normally, the allowable value for gap change (ΔX) is 2 (gm
), and a predetermined beam shape can be obtained.

On the other hand, in the case of the conventional example shown in FIG.
．． The second holder 7.9 is made of die-cast aluminum, the chip base lO is made of copper, and the collimator lens barrel 8 is made of iron, and their linear expansion coefficients α1' to α4' are αl', α2' = 2.39 (
1/"C) α3' = 1.17X I G -"
(1/'C)αa' = 1.135X I 0
-5 (1/℃).

Here, when calculating ΔX by assuming that the dimensions 1 to 4 of each part are the same, ΔX = (2,39X(1,7+9.3)-(1,1
7Xθ, 8 +1.85x 2.55) )
4 0 = 0.0057 (am) = 5.
7 [supply m], which exceeds the allowable value of ±2 (ILm).

In this case, if you try to keep it within the allowable value, the linear expansion coefficient is constant, so you have to adjust it according to the dimensional relationship of each part.
The degree of freedom in design is restricted, and the materials used for each part are also restricted.Also, if adjustments cannot be made due to dimensions, the allowable temperature range must be reduced, and if the temperature range is exceeded, temperature control is required. occurs.

On the other hand, according to the present invention, by changing the linear expansion coefficient α3 of the collimator lens barrel 8 of the resin portion, the amount of change ΔX of the gap G can be kept within the allowable value. The shape and dimensions of the second holder 7.9 etc. can be freely set, and the degree of freedom in material selection is greatly improved. Furthermore, the allowable temperature range Δt can also be expanded, eliminating the need for temperature control.

Further, in this embodiment, the collimator lens barrel 8 is made of resin, but the first. Other constituent members such as the second holder 7.9 may be made of resin, or a plurality of constituent members may be made of resin, but in the case of this embodiment, a collimator that thermally expands in the direction of narrowing the gap G is used. The first dimension in which the dimensions (i3+text 4) of the lens barrel 8 and the chip base 10 expand thermally in the direction of widening the gap G. Since it is smaller than the dimensions of the second holder 7.9 (1/2), the gap G tends to expand as the temperature rises. Therefore, making the collimator lens barrel 8 a resin part with a large coefficient of linear expansion has the highest efficiency in absorbing changes in the gap G. Also, the materials for the other components are not limited to metal, and the second holder 9 However, in the case of this embodiment, since the collimator lens barrel 8 is held by the second holder 9, the collimator lens barrel 8 may be molded from resin or the like.
Since the linear expansion coefficient of the second holder 9 needs to be higher than that of the second holder 9, it is most preferable that the collimator lens barrel 8 is made of resin.

Furthermore, if the collimator lens barrel 8 is made of a resin material as in this embodiment, dew condensation on the collimator lens 4 can be prevented due to its heat insulating properties.

Furthermore, the chip base 10 and the first. By making the second holder 7.9 made of metal with good thermal conductivity, the heat dissipation of the laser can be improved.

Therefore, it is possible to suppress the temperature rise of the assembly member due to heat generated during laser driving, and it is possible to further suppress changes in the gap G. In addition, changes in characteristics due to heat generated by the laser itself can be suppressed as much as possible, and the quality of the laser can be improved.

In addition, in this embodiment, the first. Although the second holder 7.9 is made of zinc guicast acid, it may be made of aluminum or other materials may be used.However, if it is made of zinc guicast acid as in this example, the processing accuracy will be excellent, and the post-processing There is no need for this, and processing costs can be significantly reduced.

5 and 6 show an example of an image forming apparatus to which the laser unit l of the present invention is applied. In the figures, 20 is a first optical system, and 21 is a second optical system, which is a laser scanner unit/unit. 22 is a photosensitive drum.

The first optical system 20 includes a lamp 24 that illuminates an original placed on an original table 23, and mirrors 25 and 26.

27, lens 28, and mirrors 29 and 30.

31, and the reflected light from the direct product is transmitted to mirrors 25.
26, 27, the lens 28, and further guided onto the photosensitive drum 22 via mirrors 29, 30, 31.

The second optical system 21 includes a laser beam (22) as shown in FIG.
1, a cylindrical lens 32a, a motor 32,
It has a polygon mirror 33 that is directly connected to a motor 32 and rotates in the direction of arrow G, and a toric lens (fθ lens) 34, and the laser beam emitted from the laser unit l is scanned by the polygon mirror 33. , and onto the photosensitive drum 22 via the fO lens 34.

To explain the function and configuration of the laser scanner 22) 21 which is the second optical system in the above configuration, first
There is a method in which the unit 21 is connected to the output of a computer, a word processor, etc. to function as a latent image forming means, and a composite image is formed with the image formed by the first optical system 20. A second method is to form a margin at the leading edge of an image or to erase unnecessary charges on the area on the photosensitive drum 22 between one transfer sheet and the next transfer sheet. Furthermore, thirdly, it may be used in combination with coordinate input means such as a digitizer to perform a masking function or a trimming function to erase unnecessary parts of the original image formed by the first optical system 20. Furthermore, fourthly, an add-on function may be used in which a part of the optical path of the first optical system 20 is blocked and information not written on the original image, such as date or page, is added to the part.

As shown in FIG. 5, the laser scanners 221 and 21 are suspended and fixed to the lower surface of the support plate 35 by fixing screws (not shown). Further, in this embodiment, the mirror 39 that guides the laser beam onto the photoreceptor drum 22 is also connected to the support plate 3.
It is suspended and fixed on the bottom surface of 5. Therefore, when adjusting the position of the laser scanner unit 21, the optical path B of the first optical system 1 is set parallel to the generatrix direction of the photoreceptor drum 22, and the laser scanner unit /)2
This is done by adjusting the position of the mirror 39 so that the first main scanning direction is set parallel to the generatrix direction.

When the laser chip 1 of the present invention is applied to such an image forming apparatus, the shape of the laser beam does not change due to temperature changes, and good image quality is always ensured regardless of the operating temperature environment. be able to. In addition, there is no need for space to incorporate temperature control elements, and the shape and dimensions of the laser unit can be selected according to the installation space within the device, increasing space efficiency and making the device more compact. Can be done.

Note that this is not limited to image forming apparatuses, and other C
Of course, it can be applied to various devices such as a D player.

(Effects of the Invention) The present invention has the above-described structure and operation, and the linear expansion coefficient, which is a physical property value, can be arbitrarily set as a part of the assembly member as a resin part made of a resin material with a filler added. Therefore, by selecting the linear expansion coefficient in accordance with the thermal expansion difference of each component of the assembly member, it is possible to absorb the amount of change in the gap between the laser chip and the collimator lens. Accurate beam shape can be obtained. Furthermore, since the coefficient of linear expansion, which is a physical property value, can be set arbitrarily in this way, there are no restrictions on the shape and dimensions of the assembly members, increasing the degree of freedom in design. Furthermore, since there are no restrictions on the shape, dimensions, etc. of the assembly members, it is possible to increase the allowable temperature change area. Furthermore, in order to maintain the beam shape with high accuracy, temperature control using a Peltier element or the like is not required, and various effects such as space saving and cost reduction can be obtained.

[Brief explanation of the drawing]

・Figure 1 is a vertical cross-sectional view of a laser unit according to an embodiment of the present invention, Figure 2 is a schematic configuration diagram showing the state of thermal expansion of each component of the device in Figure 1, and Figure 3 is a vertical cross-sectional view of a laser unit according to an embodiment of the present invention. FIG. 4 is a schematic exploded perspective view of the device shown in FIG. 1, FIG. 5 is a schematic configuration diagram of an image forming apparatus to which the laser unit shown in FIG. 1 is applied, and FIG. 6 is a side view of the device shown in FIG. FIG. 5 is a plan view of the laser scanner unit of the apparatus, and FIG. 7 is a longitudinal sectional view of the conventional laser unit. Explanation of symbols 1... Laser unit 2... Assembly member 3...
Laser chip 4... Collimator lens 5...
Laser element 7... First holder 8... Collimator barrel (resin part) 9... Second holder lO... Chip base 12
...Standard section G...Gap agent Patent attorney back 1) Noriyuki, 41 (k, 1 θ N ′″'' Fig. 3 Fig. 7

Claims (5)

[Claims] (1) In a laser unit in which a semiconductor laser chip and a collimator lens are integrally assembled with a predetermined gap through an assembly member, a part of the assembly member is attached to a resin material by linear expansion of the resin material. 1. A laser unit comprising a resin portion to which a filler is added in an amount that adjusts the coefficient to a value that can substantially absorb the amount of change in the gap caused by the difference in thermal expansion of the constituent parts of the assembly member. (2) The laser unit according to claim 1, wherein the coefficient of linear expansion of the filler is different from the coefficient of linear expansion of the resin material. (3) The laser unit according to claim 1, wherein the coefficient of linear expansion of the filler is smaller than the coefficient of linear expansion of the resin material. (4) The laser unit according to any one of claims 1 to 3, wherein the components of the assembly member other than the resin part are made of metal. (5) The laser unit according to any one of claims 1 to 4, wherein the resin portion is a collimator lens barrel that holds a collimator lens.