JPH01172814A - Laser unit - Google Patents

Abstract

PURPOSE:To simplify a constituted optical system and to improve the position accuracy of a stop to a laser beam by constituting a lens holding part which holds at least a collimator lens by using resin and uniting the stop with the unit. CONSTITUTION:A collimator lens barrel 4 is made of resin, its workability is good, and a minute stop part 4 can easily be molded in one body. Further, the stop part 42 is united with the collimator lens barrel 4, and then the stop part 42 is arranged accurately to the optical axis of the laser beam. Consequently, the laser beam is accurately controlled and when the unit is assembled, the stop need not be provided separately; and the number of, parts is decreased to simplify the optical system, a process of adjustment, etc., can be omitted, and the device is reduced in size and cost.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a laser unit applicable to devices that utilize laser beams, such as digital copying machines, laser beam printers, and the like.

(Prior Art) Conventionally, as this type of device, one shown in FIG. 5 is known. That is, this laser unit 10
0 is equipped with a semiconductor laser element 101, and a laser beam emitted from a light emitting chip 102 of this laser element 101 is made into a parallel beam by a collimator lens 104 held in a metal collimator barrel 103. The element 101 is held on a laser substrate 106 by an element holder 105, and the collimator lens barrel 103 is held and fixed by a lens barrel holder 107 fixed on the element holder 105.

When performing image exposure using this laser unit 100, an optical system as shown in FIG. 6 is constructed. That is, in this optical system, the laser beam emitted from the laser beam) 100 is transmitted through the cylindrical lens 1.
08 and a diaphragm 109 formed in a predetermined shape, the beam is irradiated onto a polygon mirror 110 rotating in the direction of arrow G1, and the beam reflected by the polygon mirror 110 is guided to a photosensitive drum, etc. (not shown) via a toric lens 111. . Here, the reason why the aperture 109 is provided is to restrict the laser beam to the shape of the aperture and irradiate it onto the photosensitive drum or the like in a spot shape. In addition, the above-mentioned laser unit lO
As an example of a device using O, for example, JP-A-55-4
There is an apparatus described in Japanese Patent No. 3577.

(Problems to be Solved by the Invention) However, in such a conventional example, the laser unit lOO and the aperture 109 are provided separately, and therefore, it is difficult to configure an optical system using the laser unit 100. In this case, the number of parts increases and the device configuration becomes complicated.
This causes an increase in costs.

Also, when assembling the device, the laser unit lO
Not only must O and the diaphragm 109 be assembled separately, but in order to obtain the desired spot-shaped laser beam, the diaphragm 109 must be precisely arranged with respect to the optical axis of the laser beam. Since jigs and the like are required, the assembly process becomes complicated, which also leads to an increase in costs.

To solve this problem, it is conceivable to process the collimator barrel 103 to form an aperture for the laser beam, but since the collimator barrel 103 is usually made of metal, it is difficult to create a small aperture if desired. It is difficult to form this shape, and also leads to an increase in cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and its purpose is to simplify the optical system constituted by the unit by integrating the diaphragm into the unit, and also to simplify the optical system constructed by the unit. An object of the present invention is to provide a laser unit that can improve the positional accuracy of a diaphragm with respect to a beam at a low cost.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a laser unit that emits a laser beam outputted from a laser emitting element as a parallel beam through a collimator lens attached to a holding assembly. / In the holding assembly, a lens holding part that holds at least the collimator lens is made of resin, and a laser beam output from the laser light emitting element is applied to the lens holding part in a predetermined spot shape. It is characterized by integrally forming the restricting restricting part.

(Function) In the present invention having the above configuration, since at least the lens holding portion is made of resin, the holding portion has good workability, and it is easy to integrally form the aperture portion having a predetermined opening shape. It is possible. Further, by forming the aperture part integrally with the lens holding part, the aperture part can be accurately disposed with respect to the optical axis of the laser beam, and the laser beam is accurately regulated and emitted by the aperture part.

(Example) The present invention will be explained below based on illustrated embodiments.

FIG. 1 shows the configuration of a laser unit according to an embodiment of the present invention. In the figure, l is a laser board, and a plate member made of resin or the like is used. On this laser substrate 1, a laser element 2 as a laser emitting element that outputs a laser beam and an element holder 3 that holds the laser element 2 are attached. The laser element 2 has an element substrate 20, a cylindrical copper base 21 is mounted on the element substrate 2o, and a light emitting chip 22 for emitting a laser beam is provided on the base 21. be. Further, on the element substrate 20, a base 21 and a light emitting chip 22 are provided.
A transparent cover glass 2 is provided on the front surface facing the light emitting chip 22.
4 is provided. Furthermore, a protrusion 25 is provided on the bottom surface of the element substrate 20 to come into contact with the laser substrate 1, and a spring washer 26 is fitted between the element substrate 20 and the laser substrate 1. Therefore, the laser element 2 can be minutely adjusted in angle with respect to the laser substrate 1.

The element holder 3 is a substantially circular plate made of zinc (Zn), and is provided with an opening 30 having different inner diameters in the center thereof. The locking surface 31 of the laser element 2 and the element substrate 20 of the laser element 2
is in surface contact with the top surface of. Therefore, when the element holder 3 is attached to the laser board l, the laser element 2 is abutted against the locking surface 31 of the element holder 3 by the spring washer 26, and the accurate positioning, that is, the laser element 2 is aligned with the optical axis. This makes it possible to hold it at right angles.

Note that the element holder 3 is fixed onto the laser substrate 1 using a plurality of screws (not shown).

Reference numeral 4 denotes a collimator lens barrel as a lens holding portion that holds a collimator lens 5 made of glass, and is fixed to the element holder 3 by a lens barrel holder 6 that is attached concentrically to the outer periphery of the lens barrel 4 . This collimator lens barrel 4 is made of resin so that it can be easily integrally molded, and in this embodiment, PES (polyether sulfone) is used. Moreover, PPS (polyphenylene sulfide) can also be used as another resin. A cylindrical recess 40 for concentrically fixing the collimator lens 5 is provided on one end side of the collimator lens barrel 4, that is, on the side of the light emitting chip 22, and from near the center to the other end, a laser beam is emitted. A cylindrical four part 41 having a diameter larger than the recessed part 40 is provided for this purpose. Further, between the recesses 40 and 41, an aperture portion 42 for regulating the laser beam into a desired spot shape is provided by integral molding.

FIG. 2 shows the laser beam LU viewed from the direction of arrow A in FIG. 1, that is, the direction from which the laser beam is emitted. As can be understood from the figure, the shape of the opening 42a of the diaphragm 42 is a horizontally elongated substantially elliptical shape, and the diameter of the long sleeve is smaller than the inner diameter of the recess 40. It doesn't have to be an ellipse, for example, a circle,
Although it may be rotationally symmetrical or non-rotationally symmetrical, the elliptical aperture shape of the aperture part 42 in this embodiment is adopted because a spot-shaped laser beam is irradiated onto the surface of the photoreceptor drum C, which will be described later. This is to improve the resolution in the beam scanning direction.

This collimator lens barrel 4 is fixed to the element 3 by a lens barrel holder 6 that is concentrically attached to its outer periphery. That is, the base 60 of the lens barrel holder 6 is fixed at a predetermined position on the element holder 3 using a plurality of screws (not shown) that pass through the laser substrate l, and The collimator lens barrel 4 is fixed to the inner peripheral surface of the holder 6 by flowing adhesive into the adhesive hole 62 . Note that zinc (Zn) is used as the material for the lens barrel holder 6.

In this embodiment, the laser element 2 and the collimator lens 5 are mounted on the collimator lens barrel 4 and the lens barrel holder 6.
It is configured to be held by an assembly of three members, ie, an element holder 3 and an element holder 3, in order to improve the assembly precision of the laser beam (LU). That is, in the assembly process, by adjusting the position of the lens barrel holder 6 with respect to the element holder 3 using the screw, the laser beam and the optical axis of the collimator lens 5 are aligned, and X-Y adjustment is performed. At the same time, by adjusting the position of the collimator lens barrel 4 with respect to the lens barrel holder 6, the gap between the light emitting chip 22 and the collimator lens 5 can be adjusted.

FIG. 3 shows an example of an image forming apparatus to which this embodiment is applied, and in the figure, A is a first optical system, B is a second optical system, and C is a photosensitive drum.

The first optical system A includes a lamp 11 that illuminates a document placed on a document table 10, and mirrors 12 and 13.

14, a lens 15, and mirrors 16, 17. i3. xa
, through the lens 15, and further through the mirrors 16 and 1.
7.18 onto the photosensitive drum C.

As shown in FIG. 4, the second optical system B includes the laser unit LU, the cylindrical lens SL, and the motor M.
, a polygon mirror PM that is directly connected to a motor M and rotates in the direction of arrow G, and a toric lens (fθ lens) L. Scanning with polygon mirror PM, toric lens L and mirror 19
is guided onto the photoreceptor drum C through the.

In the above configuration, the function and configuration of the laser unit LU as an embodiment of the present invention will be explained. First, the unit functions as a latent image forming means by connecting to the output of a computer, word processor, etc. There is a method of forming a composite image with an image formed by one optical system. 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 3 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 1. Furthermore, fourthly, an add-on function may be used in which a part of the optical path of the first optical system is blocked and information not written on the original image, such as the date or page, is added to the part.

In any of the above applications, it is necessary to maintain high parallelism between the main scanning direction of the scanning beam by the laser unit LU and the generatrix of the photoreceptor drum C;
When the first optical system A performs trimming, masking, and add-on functions in combination with analog exposure, the scanning beam is directed not only to the generatrix of the photoreceptor drum C but also from the first optical system A. High parallelism is always required for incident light.

By the way, the laser beam emitted from the laser unit LU is regulated by a diaphragm section 42 formed integrally with the collimator barrel 4, and then passed through the cylindrical lens S.
L, polygon mirror PM.

The light is irradiated onto the surface of the photoreceptor drum C via the toric lens L, and a predetermined image is formed. In order to improve the resolution during image formation, it is desirable that the shape of the beam that irradiates the surface of the drum C be vertically elongated with respect to the beam scanning direction S. In order to meet this demand, the shape of the opening 42a of the aperture section 42 is formed into an elliptical shape, and the fourth
As shown in Figure (b), a long sleeve is placed on the photoreceptor drum C.

The length of the minor axis is set to form a beam spot Q of 2 and 2.

However, in this case, if the beam emitted from the laser unit LU has a long elliptical shape in the direction parallel to the scanning plane, it will be irradiated onto the drum via the cylindrical lens SL, polygon mirror PM, and toric lens L. It is known that the beam formed by the beam is an ellipse with its long axis relative to the drum rotation direction. A horizontally long oval opening 42a is formed in the collimator lens barrel 4 so as to be orthogonal to each other, as shown in FIG. By adjusting the installation angle of the laser unit LU with respect to the beam irradiation direction when attaching the laser unit LU to the apparatus, a vertically elongated beam spot Q is irradiated with respect to the beam scanning direction S on the surface of the photoreceptor drum C. It may also be a configuration.

As described above, in this embodiment, the collimator lens barrel 4 is made of a resin such as PES, which has good workability and allows the minute constriction portion 42 to be easily integrally molded into the lens barrel 4. It is possible. Therefore, when assembling a digital copying machine or the like to which the laser unit (LU) of this embodiment is applied, there is no need to assemble the diaphragm separately, and the number of parts can be reduced and processes such as adjustment can be omitted, resulting in cost reduction. This has the effect of being able to achieve this goal. In addition, by integrally forming the aperture part 42 on the collimator lens barrel 4,
The aperture part 42 can be arranged with high precision with respect to the optical axis of the laser beam, and the laser beam can be regulated more accurately, resulting in improved quality when applied to digital copiers, laser beam printers, etc. This has the effect that it is possible to form an image with high quality.

Furthermore, in this embodiment, the opening 42 of the diaphragm 42
By making the shape a into an ellipse, there is an effect that when an image is formed on the photoreceptor drum C, the resolution is improved, especially when background scanning is performed.

In this embodiment, only the collimator lens barrel 4 is made of PE.
Although the lens barrel holder 6 is made of resin such as S, the lens barrel holder 6 may also be made of resin. In this case, since resin has high workability, the collimator lens barrel 4 and the lens barrel holder 6 are respectively locked. This has the effect that the collimator lens barrel 4 can be easily formed, and rotation of the collimator lens barrel 4 can be prevented during one assembly, thereby further improving the mounting accuracy. However, in consideration of changes in the gap amount between the collimator lens 5 and the light emitting chip 22 due to temperature and the heat dissipation effect against the heat generated by the laser, it is desirable that only the collimator lens barrel be made of resin.

(Effects of the Invention) In the present invention having the above configuration and operation, at least the lens holding part that holds the collimator lens in the holding assembly is made of resin, so that the workability is good and it can be easily processed. A minute constriction part can be integrally molded into the holding part. Therefore, when assembling a digital copying machine or the like to which the laser unit according to the present invention is applied, there is no need to separately provide a diaphragm, the number of parts can be reduced, the optical system can be simplified, and processes such as adjustment can be omitted. , it is possible to reduce the size and cost of the device.

In addition, by integrally forming the constriction part in the holding part,
The aperture part can be placed with high precision relative to the optical axis of the laser beam, making it possible to regulate the laser beam more accurately, which improves quality when applied to digital copiers, laser beam printers, etc. This has the effect that a high-quality image can be formed.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view showing an embodiment of a laser unit according to the present invention, Fig. 2 is an enlarged view of the same embodiment as seen from the direction of arrow A in Fig. 1, and Fig. 3 is an application of the same embodiment. FIG. 4(a) is a longitudinal cross-sectional view showing the schematic configuration of the image forming apparatus shown in FIG.
) is an explanatory diagram showing the shape of the laser beam irradiated onto the photoreceptor drum, Fig. 5 is a vertical cross-sectional view showing a conventional laser unit, and Fig. 6 is an example of an optical system configured with a conventional laser unit. FIG. Explanation of symbols 2... Laser element (laser light emitting element) 22...
Light emitting chip 4...Collimator lens barrel (holding assembly, lens holding part) 42...Aperture part 42a...Aperture 5...
・Collimator lens 6... Lens barrel holder (holding assembly) Fig. 2 Fig. 4 (a)

Claims (5)

[Claims] (1) In a laser unit in which a laser beam output from a laser emitting element is emitted as parallel light by a collimator lens attached to a holding assembly, at least a lens holding part that holds the collimator lens of the holding assembly is made of resin. What is claimed is: 1. What is claimed is: 1. What is claimed is a laser unit, characterized in that the lens holding portion is integrally formed with a diaphragm portion that regulates a laser beam outputted from the laser light emitting element into a predetermined spot shape. (2) The laser unit according to claim 1, wherein the aperture shape of the aperture portion is rotationally symmetrical. (3) The laser unit according to claim 1, wherein the aperture shape of the aperture portion is rotationally asymmetric. (4) The laser unit according to claim 1, wherein the aperture shape of the aperture portion is elliptical. (5) The laser unit according to claim 1, wherein the lens holding section made of resin is a collimator lens barrel.