JPS62209506A - Laser optical device - Google Patents

Abstract

PURPOSE:To reduce the influence upon D (the length between the light emission point of a light emitting part and the first incidence-side lens face of a collimator lens) accompanied with thermal expansions of materials due to the variation of temperature so that this influences can be ignored, by partially and effectively arranging materials having a very small coefficient of thermal expansion like a glass in a constituting part which has an influence upon the precision of D and devising selection of materials to be used. CONSTITUTION:This device is constituted to satisfy l1.beta1+l4.beta4 l2.beta2+l3-.beta3 where l1, l2, l3, l4, beta1, beta2, beta3, and beta4 are the length between the light emission point and a semiconductor laser attaching reference face, the length between the attaching reference face and the first supporting member (collar) in a part brought into contact with the second supporting member, the length of the second supporting member from the part brought into contact with the first supporting member and a fixing means, the length from the fixing means (collimator lock screw) to the first lens surface of the collimator lens, the coefficient of thermal expansion of the light emitting part, the coefficient of thermal expansion of the first supporting member, the coefficient of thermal expansion of the second supporting member, and the coefficient of thermal expansion of a barrel respectively. Variations of length l1-l4 due to thermal expansion are DELTAl1=1.7mum, DELTAl2=1.6mum, DELTAl3=0.6mum, and DELTAl4=1.2mum at 25 deg.C, and the difference between right and left terms is 0.7mum.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a Rede optical device in a device using a laser as a light source.The laser optical device of the present invention can be applied to an optical system such as a laser printer. [Prior Art] In recent years, similar to the rask scanning of televisions, recording devices such as laser printers have created an image by scanning a laser beam while modulating the laser output, and then copied the image using electrophotographic technology. VtI is attracting attention.This laser printer has features such as high resolution and the ability to perform graphic processing, and is seen as a promising new laser application technology.

As a conventional technique related to laser printers, for example, as shown in Japanese Patent Application Laid-Open No. 59-15204, in order to prevent the beam diameter on the photoconductor (P/C') from changing when the environmental temperature changes, the thermal expansion coefficient A technique has been disclosed in which two types of materials that contribute to the optical system are used for the optical system part, and a Peltier element (electronic cooling element) is used as the material for the mounting member of the laser light source to constantly control the angle at a constant 4 degrees.

In order to achieve the same purpose as in JP-A-59-152048, the collimator lens IJlti is made of Bs (copper) or 5US (stainless steel) which is less affected by thermal expansion. It discloses a technique of using two types of materials with different coefficients of thermal expansion as the materials for the optical part (the same as in Mach 6VI No. 59-15204).

In addition to these conventional techniques, the techniques shown in FIGS. 7 and 8 have been used as improved proposals in which the materials for mounting the laser light source and the collimator lens are carefully selected.

A semiconductor laser (L, D) 20, which is a light source, is fixed to the mounting reference plane PP' by a holder 21 made of aluminum. A collimator lens barrel support member 23, 23' whose one end abuts the holder 21 and supports the collimator lens barrel 22 at the other end is fixed to this reference surface. Collimator lens &l'I trunk support member 23.2
Reference numeral 3' is made of a ferrous metal material, and a collimator lens barrel 22 made of aluminum is supported therein so as to be able to freely vibrate.

The collimator lens barrel 22 is fixed at the retired position by a lock screw 24. This technology is notable in that it uses aluminum, which has good workability, as the material for the collimator lens barrel. That is, in this improved proposal, the optical part mounting portion is constructed using two types of materials: iron and aluminum.

[Problems to be Solved by the Invention] Among the conventional techniques, when a Beltier element (M pre-cooling element) is used to suppress the heat 11111j, the Beltier element itself is expensive, and the temperature of -11Xl is A thermistor and control circuit are required, resulting in a significant increase in cost. Also, the structure requires the installation of large heat dissipation fins.
Measures to prevent dew condensation on the semiconductor laser (LD), collimator lens, etc. are also required, resulting in a problem that the structure becomes complicated.

On the other hand, the collimator lens barrel is 88 (copper) or 5LI.
Even when a material with little influence of thermal expansion, such as S (stainless steel), is used, the influence of thermal expansion has become a value that cannot be ignored as the PII image power becomes higher. In addition, these materials have problems with workability.
The problem is that it is not suitable for childbirth.

Furthermore, regarding an improved example in which aluminum is used for the collimator lens barrel, as a result of experiments, ? ! It was found that thermal expansion could not be absorbed sufficiently due to rough changes. In the case of this improved example, there is still room for consideration in how to combine aluminum, which is the material of the collimator lens barrel, with other materials.

An object of the present invention is to provide a laser optical device that does not have the above-mentioned problems, can reliably absorb the effects of thermal expansion due to temperature changes, and is highly mass-producible.

[Structure of the Invention] (Means for Solving the Problems) A laser optical device according to the present invention includes a light emitting section that holds a solid state light emitting element and has a mounting reference surface, a lens barrel that holds a collimator lens surface, and one end of which is attached. Abuts against the mounting reference surface, supports the cough lens barrel with the other end, and fixes the light emitting part and the lens barrel on the same optical axis.
A laser optical device comprising a support member and a fixing means for fixing the lens barrel to the support member, wherein the support member has a first support member that abuts the mounting reference surface of the light emitting section.
It is composed of a support member and a second support member that is integrally fixed to the first support member and supports the lens barrel, and the distance in the optical axis direction is between the light emitting point of the solid state light emitting element and the mounting reference plane. The distance between the mounting reference surface and the first support member at the abutting portion between the second support member and the second support member is also 2, and the second distance from the abutment portion to the first support member to the fixing means is 1. The length of the support member is 3, and the length of the collimator lens is 1921 from the fixing means.
The distance to the surface is 4, and the thermal WB coefficient of the light emitting part is β! , the thermal expansion coefficient of the first supporting member is β2, the thermal expansion coefficient of the second supporting member is β3, and the thermal expansion coefficient of the cough lens barrel is β4. It is characterized by having a relationship of intersection 3 and β3.

In the present invention, the collimator lens barrel is constructed of an aluminum-based metal with excellent workability, and a support member is provided to hold the light emitting section including the collimator lens &1IIN4 and the semiconductor laser (solid-state light emitting device) on the same optical axis. , is divided into a first support member and a second support member. 1st
The supporting member 1'gs is a part that comes into contact with the mounting reference surface of the light emitting section, and the second supporting member is a part that is integrally fixed with the first supporting member and supports the above-mentioned lens barrel. The first support member and the second support member are each made of materials having different coefficients of thermal expansion. In other words, this distance 11
A laser optical device is obtained in which a material composition that keeps 1D constant is selected.

(Detailed Description of the Structure of the Invention) Here, the light emitting section consists of a semiconductor laser which is a light source and a mounting section to which this laser is attached.

The support member is a member whose one end abuts the mounting reference surface of the light emitting section, supports the collimator lens &fif11 at the other end, and fixes the light emitting section and 81IIi1 on the same optical axis. The fixing means for fixing &1IItl to the support member is, for example, a collimator lock that locks the collimator lens m cylinder in an appropriate position.

The first support member refers to the first support member to which the light emitting part is attached.
This is the part that comes into contact with the semi-surface.

The second support member is a portion that is integrally fixed with the first support member and supports the collimator lens barrel.

The thermal expansion coefficient β1 of the light emitting part is, for example, a semiconductor laser (L
If the lead wire connected between the light emitting point of D> and the mounting reference surface is copper, the value is 16°6X10-6 ['C
-11.

For example, when the first support member is made of glass, the coefficient of thermal expansion β2 of the first support member is 7.0×10''''['
C-'].

For example, when the second support part is made of iron, the coefficient of thermal expansion β3 of the second support part is 11.7x10-6 ['C-']
becomes.

The thermal expansion coefficient β4 of the collimator lens barrel is 23.6XIO-6[' when the barrel is made of aluminum.
C-'].

Formula cross blindness・β1+cross4・β4÷9.2・β2+cross3・β3
It is desirable that the difference between the left side and the 6th term is within ±1 μm. If tSwI imaging of laser printers becomes more advanced, a value even smaller than this value will be required.

The second support member and the lens barrel basin, for example, and 6, are made of an aluminum-based metal material, and the first support member is made of a material such as glass, which has a coefficient of thermal expansion smaller than that of the aluminum-based metal material, and the above relational expression % is used. Formula % Furthermore, the second support member and the lens barrel may be made of the same aluminum-based metal material, and the first support member may be made of ceramics, thereby obtaining the above-mentioned formula II.

That is, in the configuration of the present invention, the support member is the first and second support member.
The feature is that each support member is made of a different material, and the optimal combination of these support members and the aluminum metal used as the collimator lens barrel material is determined by temperature changes. This minimizes the effects of thermal expansion.

[Embodiments of the Invention] FIG. 1 shows the overall configuration of the optical section of a laser printer. Here, a semiconductor laser (LD) 1 is used as an example of a laser light source.
A case in which a solid-state light emitting device such as the one shown in FIG. 1 is used will be explained.

The light beam emitted from the semiconductor laser (+-D) 1 is made into parallel light by the collimator lens 2, and then the reflecting surface of the rotating polygon mirror 4 is used for optical correction by the combination of the cylindrical lens 3 and the toroidal lens 5. The light is focused on. The rotating polygon mirror 4 deflects and scans the incident laser light in a fan shape. The light scanned in this way is returned to parallel light by the toroidal lens 5, passes through an fθ lens group 6 that converts the laser light into a spot light of a predetermined diameter, focuses the light, and is then focused by a folding mirror 7. A photoreceptor (drum-shaped) 81 made of a conductor is folded back and exposed.

The start of scanning is sensed by the SOS mirror 9 and the SOS sensor 10. Note that the photoreceptor 8 is first charged and then exposed to laser spot light. After that, although not shown, printing is completed by development, transfer, and fixing steps.

In such laser printers, as the recording speed increases, high-quality images with high resolution are required, and the diameter of the spot light on the photoreceptor, which is the imaging surface, needs to be smaller. It becomes.

Due to this demand for higher resolution, the dimensional accuracy of the depth of the collimator lens 2, that is, the distance between the laser emission point S and the first surface L+ of the incident side lens of the collimator lens 2, has been increased as shown in Fig. 2. There is a need to. This D is greatly amplified and affects the beam diameter on the photoreceptor by several hundred times. That is, it is also affected by μ-order changes in thermal expansion due to temperature changes. In order to absorb as much as possible the variation in vJ caused by temperature changes in It was constructed as shown in Figures 3 and 4.

As shown in FIGS. 3 and 4, the semiconductor laser (LD) 1 is a semiconductor laser (LD) made of Bs (copper) material.
D) with the semiconductor laser holder 12 on the mounting reference plane P-P.
= was fixed with an optical axis adjustment screw 13, and this was used as a light emitting part. Further, a collar 14.14' made of glass with a small coefficient of thermal expansion is mounted and fixed with an optical axis adjustment screw 15.15' to the mounting reference plane P-P= of the light emitting part, and these collars 14.14' A second support member 17.17- whose one end abuts and the other end supports the collimator lens barrel 16 is the optical axis! ! It was fixed to the mounting reference plane PP- using I screws 15 and 15', and the light emitting part and m1116 were fixed on the same optical axis. Collimator lens 1lIi! The collimator lens barrel 16 made of aluminum is held slidably in the optical axis direction by support members (second support members) 17 and 17', and the collimator lens barrel is held at an appropriate position by the collimator lock screw 19, which is a fixing means. It can be locked with . Support member 18
．． 18- is composed of a first support member constituted by a collar 14, 14' and a second support member 17, 17' which is integrally fixed with the first support member and supports the lens barrel.

Further, the semiconductor laser (LD) holder 12 also serves as a heat sink. After adjusting the entire holder 12 in the Y direction (main scanning direction) and the J direction (sub scanning direction), it was fixed to the reference surface using an optical axis adjustment screw.

Further, the collimator lens barrel 16 was supported in a holder 17, 17-, adjusted in the X direction (laser traveling direction) with an external jig, and fixed with a lock screw 19.

Generally, during beam diameter fluctuations that do not affect images, it is about ±10% of the beam diameter on the photoconductor (I: 4 optical beams).
From the following equation, if the reverse W'l is allowed to fluctuate in D, ±1.
1 μm (see Figure 5) 10% defocus pre-4λ −1.3 mm D−x/(fθ/fc)2÷1.1 μmd o −25
, 4/480÷53μmfθ=fθ lens focal length M
(350mm) f c -=+ +) meter focal length l1
11 (9mm) Collimator lens In order to reduce the effect of thermal expansion on the lens barrel, the distance between the lock position of this lens barrel and the first lens surface on the incident side should be made as short as possible. The holding of the torso itself becomes uncertain.

Shake for this! ! 1JWe19 has been confirmed to cause pitch unevenness and optical axis deviation in two directions (sub-scanning direction).

The present invention prioritizes the use of highly productive aluminum as the lens barrel material, and even when aluminum with a large coefficient of thermal expansion is used for the human body, it is easy to absorb the effects of thermal expansion and has a high In order to reliably hold the collimator lens barrel, which is becoming larger as resolution increases, more than half of the lens barrel is housed in the collimator lens barrel holder through precise fitting.

In this embodiment, as shown in FIG. 6, the collimator lens barrel support member 23.
' (see Fig. 7) is divided into a first support member that comes into contact with the mounting reference plane P-P- and a second support member that is integrally fixed with this first support member and supports the lens barrel. 1. Collar whose support member is made of glass with a very small coefficient of thermal expansion 14.
It was set to 14'.

Here, the distance between the light emitting point and the semiconductor laser mounting reference surface is determined by changing the distance between the light emitting point and the semiconductor laser mounting reference surface, and the distance between the mounting reference surface and the second support member and the first
The distance of the support member (collar) is 22, the length of the second support member from the part that contacts the first support member to the fixing means (collimator lock screw) is also 3, and the length from the fixing means (collimator lock screw) to the collimator lens The distance to the 1121st surface of the
When the coefficient of thermal expansion of the supporting member is β2, the coefficient of thermal expansion of the second supporting member is β3, and the coefficient of thermal expansion of the lens barrel is β4! 1・β++R4・β4≒l2・β2 +9. s・β3
I made it so that the relationship is as follows.

From the above formula, when the temperature is 25℃, it is 5! ri, again 2, again 3
．． The variation due to thermal expansion of fL4 is Δ or +=4X16.6X10-6X25≠ 1, 7μ
m Δcross z=9×7.0 The difference is 0.7 μm ±
The change is 0.35 μm. This difference is within ±1 μm, which is currently within the desired ε) value range, but as higher resolution becomes required, this difference will need to be reduced as described above. .

In addition to the material configuration as in this embodiment, for example, the lens barrel and aJl
It is also possible that the holder is made of a metal material having substantially the same coefficient of thermal expansion, and that a portion of the collar is made of ceramics.

[Effects of the Invention] The laser optical device according to the present invention achieves cost reduction by mainly using aluminum, which is highly workable and highly productive, for the optical parts around the semiconductor laser light source, such as the collimator lens barrel. . In particular, by arranging components that have an effect on the accuracy of D mentioned above using materials such as glass that have a very small coefficient of thermal expansion, and by carefully selecting the materials used, thermal expansion of the material due to temperature changes can be achieved. This makes it possible to maintain the influence on D at a negligible value.

[Brief explanation of drawings]

Figure 1 explains the overall configuration of the optical section of a laser printer'!
J6 explanatory diagram, Figure 2 is a semiconductor laser (LD) that is a light source
FIG. 3 is an explanatory diagram showing the optical positional relationship between the collimator lens and the collimator lens. FIG. 3 shows a detailed structure of an embodiment of the present invention, and FIG. 4 is a rear view of the same. FIG. 5 is an explanatory diagram of the variable width of the beam system, and FIG. 6 is a schematic diagram of an actual example of the present invention. FIG. 7 is a detailed diagram showing the configuration of the conventional device.
The figure is a rear view of the same. 1... Semiconductor laser (solid-state light-emitting device) 11... Semiconductor laser (solid-state light-emitting device) and collimator lens assembly section 12... Semiconductor seat 1a (solid-state light-emitting device) holder 14
．． 14'...Glass collar (first support member) 16.
...Collimator lens barrel 17.17'...Collimator lens barrel support member (second support member) 18.18'...Support member patent applicant Minolta Camera Co., Ltd. agent
Patent attorney Hirodo Okawa Patent attorney Akio Maruyama Figure 1

Claims (3)

[Claims] (1) A light-emitting part that holds a solid-state light-emitting element and has a mounting reference surface, a lens barrel that holds a collimator lens, one end of which is in contact with the mounting reference surface, the other end of which supports the lens barrel; and a support member for fixing the lens barrel on the same optical axis, and a fixing means for fixing the lens barrel to the support member, wherein the support member is located on the mounting reference surface of the light emitting section. and a second support member that is integrally fixed with the first support member and supports the lens barrel, the light emitting point of the solid state light emitting element being at a distance in the optical axis direction, The distance to the mounting reference plane is l_1, the distance between the mounting reference plane and the first support member at the abutting part between the second support member and the second support member is l_2, and the distance from the part abutting the first support member to the fixing means is The length of the second support member is l_3, the distance from the fixing means to the first lens surface of the collimator lens is l_4, and
The coefficient of thermal expansion of the light emitting part is β_1, the coefficient of thermal expansion of the first support member is β_2, and the coefficient of thermal expansion of the second support member is β_3.
And when the thermal expansion coefficient of the lens barrel is β_4, l_1・β
_1+l_4・β_4≒l_2・β_2+l_3・β_
3. A laser optical device characterized by having the following relationship. (2) The material with a coefficient of thermal expansion β_1 is Bs (copper) etc.
2. The laser optical device according to claim 1, wherein the material having a coefficient of thermal expansion β_2 is glass or the like, the material having a coefficient of thermal expansion β_3 is an iron-based metal, and the material having a coefficient of thermal expansion β_4 is aluminum or the like. (3) The second supporting member and the lens barrel are made of a metal material having substantially the same coefficient of thermal expansion, and the first supporting member is made of a material having a smaller coefficient of thermal expansion than the metal material. Laser optical equipment.