JP3400574B2 - Resin lens - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin lens, and more particularly to a resin lens of a scanning optical device for scanning a laser beam and recording an image in a digital copying machine, a laser printer, a laser facsimile or the like.

[0002]

2. Description of the Related Art In recent years, a glass lens and a synthetic resin lens are mixed and used as an image forming lens of a scanning optical device for scanning a laser beam to record an image in a digital copying machine, a laser printer, a laser facsimile or the like. What you have done is known.

However, as described above, when a glass lens and a synthetic resin lens are mixed and used as the image forming lens, there is a difference in the coefficient of thermal expansion between the glass lens and the synthetic resin lens, so that the distance between the lenses increases. There is a problem that the optical axis shift occurs. In order to eliminate such a problem, conventionally, the heights of the fixed surface of the synthetic resin toric lens and the fixed surface of the glass lens are selected based on the coefficient of thermal expansion of these lenses and the coefficient of thermal expansion of the optical box. Then, the optical axis positions are made to coincide with each other even if there is a temperature change.
A "scanning optical device" described in Japanese Patent No. 518 has been proposed.

Further, conventionally, in order to simplify the mounting of the optical lens to improve the productivity, and to improve the mounting accuracy and the optical performance, the first optical lens is integrated with the lens holder made of synthetic resin mold. And a lens positioning guide part for positioning the second optical lens, which is a separate body, are formed integrally with the lens holder, and the second optical lens is positioned at a predetermined position by using these positioning guide parts as guides. A "lens holder unit" described in JP-A-4-345122, which is configured to be fixed, has been proposed.

[0005]

However, in the conventional "scanning optical device" described in JP-A-4-336518 and "Lens holder unit" described in JP-A-4-345122, a synthetic resin toric is used. Since the coefficient of thermal expansion of the lens and the glass lens or the first optical lens and the second optical lens is fundamentally different, even if the difference in the coefficient of thermal expansion of each lens is taken into consideration in advance, the fixing surface of each lens Even if the height of the lens is selected, the positional deviation of the optical axis due to the temperature change of these lenses cannot be completely eliminated.

Further, in these conventional examples, since the synthetic resin toric lens and the glass lens, or the first optical lens and the second optical lens are separately configured, the number of parts and the number of mounting steps are reduced. Increase,
There is a problem that an assembly error occurs such that the front and rear surfaces of the lens are reversed.

The present invention has been made in view of the above points, and an object thereof is to reduce the number of parts and the number of mounting steps, and to completely eliminate the positional deviation of the lens optical axis due to temperature change. It is to provide a resin lens that can be used.

[0008]

In order to solve the above-mentioned problems, the present invention provides, in claim 1, two or more imaging lenses.
, Multiple lens holders and lens holder are made of synthetic resin
For resin lenses integrally molded by molding,
The lens presser for the imaging lens is independent and
A plurality of lens retainers are formed in substantially the same shape .

According to a second aspect of the present invention, the lens retainer is
The lens is arranged on the side surface of each lens.

According to the third aspect of the invention, the upper portion or the lower portion of each lens of the lens holder is formed in a hollow structure.

According to a fourth aspect of the present invention, the lens holder has a positioning hole or a positioning protrusion for positioning the lenses.

According to a fifth aspect of the present invention, the lens holder has a lens attachment reference portion larger than the size of each lens in the longitudinal direction.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, a conventional scanning optical device in which a resin lens according to the present invention is mounted will be described with reference to FIG. In FIG. 5, an image writing signal is emitted as a laser beam from a semiconductor laser 200 arranged in a casing 100 of a laser writing unit through a cylindrical lens 300 and is rotated by a drive motor (not shown). The two lenses 500, 600 and the mirror 70 are rotated and scanned by the polygon mirror 400.
The charged photoconductor (not shown) is exposed through 0.

In this conventional scanning optical device, each lens 5
00 and 600 are configured to be individually positioned by the positioning reference members 100a, 100b, 100c, and 100d provided in the housing 100, and therefore, the number of components and the number of assembling steps of each lens are increased. Due to variations in mounting accuracy, optical axis shifts and the like are likely to occur, resulting in reduced optical performance and increased cost.

In order to solve such a problem, a scanning optical device using a resin lens as described above has also been proposed. However, in these conventional techniques, as described above, the number of parts and the assembling are required. It has not been possible to completely eliminate the increase in the number of processes and the deviation of the optical axis due to the temperature change.

Therefore, in the resin lens of the present invention, as shown in FIG.
As shown in FIG. 3, the plurality of lenses (the number of which is two in the present embodiment, but the number is not limited) in the above-described scanning optical device are configured by the imaging lenses 1 and 2 made of synthetic resin, and Two or more imaging lenses 1 and 2,
The lens holder 3 made of synthetic resin is integrally molded with the lens holder 3 via the lens holders 1a and 2a having substantially the same shape.

According to this embodiment, the respective imaging lenses 1 and 2 are
However, since it is integrally formed with the lens holder 3 through the lens pressers 1a and 2a, the number of parts and the number of assembling steps are reduced, and as shown in FIG.
Since the shape of a is formed to be substantially the same, the deformation amounts thereof due to the temperature change are substantially the same, and the lens optical axes O of the imaging lenses 1 and 2 are always aligned.

In this embodiment, as shown in FIG.
Lens holders 1a and 2a are arranged on the side surfaces of the respective imaging lenses 1 and 2. Therefore, according to the present embodiment, the shape of the lens pressers 1a and 2a can be molded into the same shape without depending on the shape and size of the imaging lenses 1 and 2, and thus the lens pressers 1a and 1a can be molded. The influence of heat or the like on 2a is stabilized irrespective of the lens shape, and the deviation of the lens optical axis O of each of the imaging lenses 1 and 2 due to the temperature change is suppressed.

Further, in this embodiment, as shown in FIGS. 1 to 3, the lower portions of the respective imaging lenses 1 and 2 of the lens holder 3 are formed in a hollow structure. Therefore, according to the present embodiment, a mold (not shown) for molding the lens surfaces of the respective imaging lenses 1 and 2 can be easily pulled out through the hollow portion below the lens holder 3, Each imaging lens 1,
This facilitates the processing for integrally molding 2 and the lens holders 1a, 2a and the lens holder 3.

In this embodiment, as shown in FIGS. 1 to 3, the lens holder 3 is formed with a positioning hole 4 and a positioning recess 4a for positioning the imaging lenses 1 and 2. .. Therefore, according to the present embodiment, the positions of the respective imaging lenses 1 and 2 are simultaneously positioned, and the respective imaging lenses 1 and 2 are accurately attached.

Further, in this embodiment, as shown in FIGS. 1 to 3, the lens holder has a lens mounting reference portion (lower surface of the lens holder 3) larger than the size of the imaging lenses 1 and 2 in the longitudinal direction. )have. Therefore, according to this embodiment, the longitudinal inclination (eccentricity) of each of the imaging lenses 1 and 2 is suppressed, and the image quality during image scanning is stabilized.

By the way, in the above-mentioned embodiment, an example in which the respective imaging lenses 1 and 2 are positioned by the positioning hole 4 and the positioning recess 4a provided in the lens holder 3 has been shown. As a positioning means for the lenses 1 and 2, as shown in FIG. 4, a positioning projection 7 is formed in the lower part of the lens support 6, and the positioning projection 7 is fitted into the reference groove 8 of the substrate 10. The imaging lenses 1 and 2 may be positioned on the surface 9. In the embodiment shown in FIG. 4, each of the image forming lenses 1 and 2 includes a corresponding lens retainer 1b,
2b, the lens support 6 is integrally molded by a synthetic resin mold, and a mold (not shown) for molding the lens surfaces of the imaging lenses 1 and 2 is removed. In order to facilitate the above, the upper portions of the respective imaging lenses 1 and 2 are formed in a hollow structure.

[0023]

As described above, according to the present invention, in claim 1, since each image forming lens is integrally formed with the lens holder through the lens retainer, the number of parts and the number of assembling steps are increased. In addition, since the shape of the lens retainer is formed to be substantially the same, the amount of deformation due to the temperature change becomes substantially the same, and the lens optical axes of the respective imaging lenses should always be aligned. The image quality can be stabilized.

According to the second aspect of the present invention, since the shape of each lens retainer can be molded into the same shape without being influenced by the shape and size of each imaging lens, the influence of heat or the like on each lens retainer can be changed to the lens shape. Therefore, it is possible to stabilize the temperature, and it is possible to suppress the deviation of the lens optical axis of each imaging lens due to the temperature change.

In the third aspect, the mold for molding the lens surface of each image forming lens can be easily removed through the hollow portion below the lens holder, and each image forming lens, each lens pressing member and This facilitates the processing when integrally molding the lens holder.

According to the present invention, since the positions of the respective image forming lenses can be simultaneously positioned, the respective image forming lenses can be attached with high accuracy.

According to the fifth aspect, the inclination (eccentricity) of each imaging lens in the longitudinal direction can be suppressed, and the image quality during image scanning can be stabilized.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of an embodiment of a resin lens of the present invention.

FIG. 2 is a schematic sectional view along the optical axis of the above embodiment.

FIG. 3 is a schematic plan view of the above embodiment.

FIG. 4 is a schematic perspective view of another embodiment of the resin lens of the present invention.

FIG. 5 is a schematic plan view of a conventional scanning optical device in which the resin lens of the present invention is mounted.

[Explanation of symbols]

1, 2 imaging lens 1a, 1b, 2a, 2b Lens presser 3 lens holder 4 Positioning hole 4a Positioning recess 6 lens support 7 Positioning projection 8 reference groove 9 Reference plane O lens optical axis

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-63-210807 (JP, A) JP-A-4-345122 (JP, A) JP-A-5-34617 (JP, A) JP-A-3- 33801 (JP, A) JP-A-4-161911 (JP, A) Actually opened 63-94412 (JP, U) Actually opened 3-62307 (JP, U) Actually opened 63-94413 (JP, U) Actually open 61-198912 (JP, U) Actually open 2-117501 (JP, U) Actually open 63-122311 (JP, U) Actually public 52-25159 (JP, Y1) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02B ⁷ /02-7/16

Claims (5)

(57) [Claims] 1. A plurality of imaging lenses and a plurality of lens pressing lenses.
The lens holder and the lens holder are integrated with a synthetic resin mold
In the molded resin lens, the lens presser for each imaging lens is independent, and the plurality of lens pressers are molded in substantially the same shape.
A resin lens that is characterized by 2. The resin lens according to claim 1, wherein the lens retainer is disposed on a side surface portion of each lens. 3. The resin lens according to claim 1, wherein an upper portion or a lower portion of each lens of the lens holder is formed in a hollow structure. 4. The resin lens according to claim 1, wherein the lens holder has a positioning hole or a positioning protrusion for positioning the lenses. 5. The resin lens according to claim 1, wherein the lens holder has a lens attachment reference portion larger than the size of each lens in the longitudinal direction.