JP2002316226A - Pressed optical element and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy of the optical surface of a pressed optical element and accurately build-up the element into an optical device. SOLUTION: A cylindrical reference part 12 is formed by drawing a metallic plate and the circumferential surface of the reference part 12 is adopted as a reference face 13. A concave optical face formation part 15 is formed at the flat part 14 of the upper part of the reference part 12 by taking the reference face 13 as a reference, and the upper face of the optical face formation part 15 is used as an optical face 16. An annular flange part 17 is formed at the lower part of the reference part 12. The reference part 13 is used as a reference when the optical face formation part 15 is formed and is also used as a reference when the pressed optical element 11 is built-up into the optical device. Chips, burrs, or turning-backs are not generated when the reference face 13 is formed, and further the fitting length of the reference face 13 is made long.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressed optical element formed by pressing a metal plate and having an optical surface usable for a reflection optical system, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as a general method for manufacturing an optical element of a reflection optical system, a method of mechanically processing a glass material by grinding and polishing, and a method of forming a metal reflection film on a plastic molding material. A method of forming by vapor deposition or the like is known. As a simplest method for manufacturing this kind of optical element, a method of pressing a metal plate having a high reflectance is disclosed in Japanese Patent Application Laid-Open No. 8-36222. In this method, a curved mirror that simply reflects an image is formed by pressing only an optical surface on a metal plate.

On the other hand, a press mirror 1 as shown in FIG. 15 is known as a high-precision optical element used by being incorporated in an optical device. The press mirror 1 has an optical surface forming portion 3 at the center of the flat portion 2, and the outer peripheral surface of the flat portion 2 is used as a reference surface 4 when assembling the optical device.

The press mirror 1 is shown in FIG.
It is manufactured by a typical progressive press working process as shown in (a) to (c). That is, FIG. 16A shows the first step, in which the left and right reference holes 5a and 5b are sheared in a metal plate M which is a strip or a hoop material. FIG. 16B shows a second step, in which the optical surface forming part 3 is processed by plastic deformation at the center of the flat part 2 with reference to the reference holes 5a and 5b. FIG.
(C) shows a third step, in which the front and rear tie bars 6a, 6b
Are left and right spaces 7a and 7b are punched out, and the flat portion 2 is supported on the metal plate M in a semi-fixed state via tie bars 6a and 6b. Note that the order of the second step and the third step may be reversed.

[0005] The conventional press mirror 1 is conveyed to the metal plate M while being held via the tie bars 6a and 6b, and cuts off the tie bars 6a and 6b as necessary to separate from the metal plate M. Then, the press mirror 1 is incorporated in the optical device with reference to the reference surface 4 of the press mirror 1. At this time, the press mirror 1 secures the accuracy of the optical surface forming unit 3 with reference to the reference holes 5a and 5b, and assembles the optical device with the optical surface forming unit 3 with the reference surface 4 as a reference. Is secured.

[0006]

Here, the problem in manufacturing the conventional press mirror 1 will be briefly described with reference to FIGS. Reference hole 5a to be formed in the manufacture of pressed mirror 1, since 5b is a standard provisional reference hole 5a, the machining error between 5b and the optical surface forming unit 3 and sigma _1, reference holes 5a, 5b and reference Assuming that the processing error with respect to the surface 4 is σ ₂ , the processing error σ _P when considering the reference surface 4 as a reference is σ _P = σ ₁ + σ _{2 at} worst. Therefore, when the embedded error when incorporating the press mirror 1 in the optical apparatus and sigma _A, the final error _{σ σ = σ 1 + σ 2} +
σ _A , and all machining errors σ _P and built-in errors σ _A accumulate, making it difficult to increase the accuracy of the press mirror 1.

In addition, since the reference holes 5a and 5b are subjected to shearing in the first step, chips, burrs, returns, etc. are generated, and these are brought into the second step, so that the processing errors σ ₁ , σ ₂ is further increased. Then, the optical surface forming unit 3
If a chip is inserted when forming the surface, the surface accuracy of the optical surface forming unit 3 is impaired.

Further, as shown in FIG.
Not only fits into the fitting groove Sa of the to-be-installed part S of the optical device, but also selects a material as thin as possible for the metal plate M so as to satisfy the function as a structure and to facilitate pressing. Therefore, the length of the reference plane 4 in the direction along the optical axis, that is, the fitting length is short even after the press mirror 1 is subjected to shearing or drawing. Accordingly, when the press mirror 1 is fitted into the fitting groove Sa, the tilt eccentricity θ occurs.

In addition, since burrs, return, and the like are generated on the reference surface 4, it is easy to be squeezed when the press mirror 1 is incorporated into the fitting groove Sa, and it becomes difficult to incorporate the press mirror 1 into the fitting groove Sa. Then, as shown in FIG. 19, the press mirror 1 is inserted into the fitting groove Sa.
In the case where the optical surface forming portion 3
To transform.

Further, in order to ensure the reflectance as the press mirror 1, a material having high purity is selected for the metal plate M. Therefore, the higher the purity of the metal plate M, the higher the reflectance and the lower the rigidity. Therefore, it is difficult for the metal plate M to achieve both the reflectance and the rigidity. The higher the purity of the metal plate M, that is, the higher the reflectance, the more easily the metal plate M is oxidized.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a pressed optical element which can improve the precision of an optical surface and can be incorporated into an optical device with high accuracy, and a method for manufacturing the same.

[0012]

According to a first aspect of the present invention, there is provided a press optical element comprising a metal plate pressed and having an optical surface usable for a reflection optical system. A press optical element characterized in that a reference portion for assembling into an optical device is formed by drawing.

According to a second aspect of the present invention, there is provided a press optical element formed by pressing a metal plate and having an optical surface usable for a reflection optical system. A pressed optical element having a length greater than a thickness of the metal plate.

According to a third aspect of the present invention, there is provided the press optical element according to the first or second aspect, wherein an outer peripheral portion of the reference portion has a cylindrical or rectangular tube shape.

According to a fourth aspect of the present invention, the reference portion is set to 3
2. A projection divided into two or more parts.
Or a press optical element according to 2.

According to a fifth aspect of the present invention, the metal plate is provided on a first soft metal substrate and the second soft metal substrate has a higher purity than the first soft metal substrate. The pressed optical element according to claim 1, wherein the pressed optical element is constituted by a soft metal substrate.

According to a sixth aspect of the present invention, the soft metal substrate is an aluminum substrate.
2. The press optical element according to item 1.

According to a seventh aspect of the present invention, there is provided the press optical element according to the fifth aspect, wherein a silicon dioxide-based film is applied on the second soft metal substrate.

The present invention according to claim 8 is a method of manufacturing a pressed optical element having an optical surface usable for a reflective optical system by pressing a metal plate, wherein the metal plate is formed after the optical surface is formed. A method for producing a pressed optical element, comprising the step of shearing

According to a ninth aspect of the present invention, there is provided a displacement information detecting apparatus for detecting rotation information and movement information of a displaced object by utilizing diffraction of a light beam. A displacement information detecting device provided with the above press optical element.

According to a tenth aspect of the present invention, there is provided an image forming apparatus for forming an image by scanning and exposing a light beam on a photoreceptor, the press optical element according to any one of the first to seventh aspects. An image forming apparatus comprising:

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a plan view of a press optical element 11 of the first embodiment, FIG. 2 is a cross-sectional view, and the press optical element 11 is, for example, a concave mirror.
Pressed from a metal plate such as a strip or a hoop material. The press optical element 11 has a cylindrical reference portion 12. For example, an outer peripheral surface of the reference portion 12 is a reference surface 13. An optical surface forming portion 15 having a concave shape is formed in the flat portion 14 at the upper end of the reference portion 12. And the reference part 1
An annular flange portion 17 is provided at the lower end of 2.

Here, the reference surface 13 is used as a reference when forming the optical surface forming portion 15 and also as a reference when assembling the press optical element 11 into an optical device. The press optical element 11 can be a spherical mirror, an elliptical mirror, a parabolic mirror, an aspherical mirror, a free-form mirror, or the like. Needless to say, the inner surface of the reference portion 12 may be used as the reference surface.

FIG. 3 is a composition diagram of a metal plate A which is a material of the press optical element 11. The metal plate A is a laminate of a lower first aluminum substrate A1 and an upper second aluminum substrate A2. I have. The aluminum component of the first aluminum substrate A1 is, for example, 99%, and its thickness is, for example, 0.8 mm. Second aluminum substrate A
2, the aluminum component is, for example, 99.8% or more;
Its thickness is, for example, 0.2 mm. The first and second aluminum substrates A1 and A2 are formed by rolling using rolling rollers.

The higher the aluminum component of the second aluminum substrate A2, that is, the higher the purity, the better the reflection characteristics or the reflection directivity of the surface, but the mechanical rigidity decreases. However, since the rigidity of the first aluminum substrate A1 supplements the rigidity of the second aluminum substrate A2,
The aluminum substrate A2 can maintain good reflection directivity.

As shown in FIG. 4, a silicon dioxide glassy film A3 is formed on the surface of the second aluminum substrate A2.
Is applied, the reflectance and weather resistance can be improved. That is, in order to form the glassy film A3, a solution containing hydroxysilane as a main component is applied, dipped, or sprayed on the surface of the second aluminum substrate A2 to form a glassy film A3.
Sinter at a temperature of ~ 450 ° C. This glassy film A3
Has a smaller number of pores as compared with the case formed by vapor deposition, so that the invasion of steam is favorably prevented, the oxidation and corrosion of the second aluminum substrate A2 are prevented, and the weather resistance is improved.

FIGS. 5A to 5C show the press optical element 11.
5A is a manufacturing process diagram, FIG. 5A shows a first process,
By drawing the metal plate A, a cylindrical reference portion 12 is formed.
To form At this time, the metal plate A is plastically deformed, the outer peripheral surface of the reference portion 12 becomes the reference surface 13, and the flat portion 14 remains on the reference portion 12. FIG. 5B shows a second step,
With reference to the reference surface 13 formed in the first step, a concave optical surface forming portion 15 is formed at the center of the flat portion 14, and the upper surface thereof is used as an optical surface 16. FIG. 5C shows a third step, in which an annular flange portion 17 and front and rear tie bars 18a,
Left and right spaces 19a and 19b are punched around the flange portion 17 so as to leave 8b. Thereby, the flange portion 1
The press optical element 11 in which 7 is connected to the metal plate A in a semi-fixed state via the tie bars 18a and 18b is completed.

The tie bars 18a and 18b are provided for easily transporting the press optical element 11.
Therefore, when assembling the press optical element 11 into the optical device, the press optical element 11 is separated from the metal plate A by first cutting the tie bars 18a and 18b. And
As shown in FIG. 6, the press optical element 11 is incorporated into the optical device such that the reference portion 12 of the press optical element 11 is fitted into the fitting hole Sa of the installation target portion S of the optical device.

In the first embodiment, the pressed optical element 11 is manufactured with the reference surface 13 as a reference and the pressed optical element 11 is incorporated in the optical device with the reference surface 13 as a reference. In addition to being formed with high precision, the press optical element 11 can be incorporated into the optical device with high precision.

The reason for this is simply described in one dimension only. Since the optical surface forming portion 15 is formed with reference to the reference surface 13, the processing error σ _P is only σ _P = σ ₁ as shown in FIG. Become. Then, assuming that the installation error when the press optical element 11 is incorporated into the optical device with reference to the reference plane 13 is σ _A , the final error σ is σ = σ ₁ + σ _A , and the installation accuracy is significantly improved. .

In the first step, since the metal plate A is merely drawn, that is, plastically deformed, no chips, burrs, return, etc. are generated, and the optical surface forming portion 15 is formed with high precision. It is possible to do. The length of the reference surface 13 formed in the first step in the optical axis direction, that is, the fitting length of the optical device into the fitting hole Sa can be made larger than the thickness of the metal plate A. Accordingly, the inclination eccentricity θ of the optical surface forming unit 15 when the press optical device 11 is incorporated into the optical device.
₁ is much smaller than the conventional tilt eccentricity θ shown in FIG.

Further, when the press optical element 11 is incorporated in the optical device, burrs and return do not become a hindrance, and the press optical element 11 can be easily incorporated in the optical device. Further, since the rigidity of the reference portion 12 is higher than that of a normal single plate, the reference portion 12 is not distorted when the press optical element 11 is incorporated in the installation target portion S, and the press optical element 11 is moved to the installation target portion S. The precision of the optical surface 16 can be maintained high after the optical surface 16 is assembled. Then, as shown in FIG. 8, the press optical element 1 is also provided on the thin plate-like to-be-installed portion S 'such as a press sheet metal.
1 can be easily incorporated.

FIG. 9 is a sectional view of a displacement information detecting device using the above-mentioned press optical element 11. As shown in FIG. In this displacement information detecting device, a light source 22 and three light receiving elements 2
3 are arranged. The light source 22 has a wavelength of 632.8 nm.
LEDs and semiconductor lasers that emit coherent light beams. A lens system 24 composed of a spherical lens or an aspherical lens is assembled to the base 21. An optical scale 25 is arranged above the lens system 24, and the light source 22
Is focused by the lens system 24 and guided to the optical scale 25.

The optical scale 25 has a phase difference detecting function and an amplitude type diffraction grating function. A plurality of radial gratings having a constant period, for example, V-groove gratings having 2500 or 5000 slits are formed on the surface of a disk-shaped substrate. Is provided. The substrate of the optical scale 25 is made of a porous optical material, is attached to a part of a rotating body (not shown), and rotates integrally with a rotating shaft 27 thereof. The above-described press optical element 11 is incorporated in a frame 28 supported by the base 21 above the optical scale 25.

The pressed optical element 11 is made to coincide with the Fourier transform plane of the grating 26 so that the light beam incident on the first area of the optical scale 25 is diffracted by the grating 26.
At this time, the n-th order diffracted light beam (0th order and ± 1st order diffracted light beams L
(0), L (+1), L (-1)) are the pressed optical elements 1
Each element is set so as to converge light on one optical surface 16. The optical axis O of the press optical element 11 and the central ray of the incident light beam are decentered.

The press optical element 11 is a convergent light beam (three diffracted light beams L (0),
L (+1), L (-1)), and the optical scale 2
An interference pattern image based on three diffracted light beams is re-imaged on the second regions on the five surfaces. At this time, when the optical scale 25 rotates, the interference pattern image moves in a direction opposite to the rotation direction. In other words, the grating section 26 and the interference pattern image are relatively displaced by a value twice as large as the moving amount of the optical scale 25, thereby obtaining rotation information having twice the resolution of the grating section 26.

Then, the interference pattern image and the V
The light beam based on the phase relationship with the groove is geometrically refracted in the second region, and the three emitted light beams are detected by the three light receiving elements 23, respectively. The signals from these light receiving elements 23 are processed by a signal processing circuit having a pulse count circuit and a rotation direction discrimination circuit to obtain rotation information. Since the displacement information detection device uses the high-precision press optical element 11, the displacement information detection accuracy can be improved.

FIG. 10 is a plan view of the press optical element 31 of the second embodiment, and FIG. 11 is a cross-sectional view. The press optical element 31 is a convex mirror, and has the same steps as those of the first embodiment. Being manufactured. The press optical element 31 includes a cylindrical reference portion 12, a reference surface 13, a flat portion 14, an optical surface forming portion 15, an optical surface 16, and a flange portion 17 according to the first embodiment.
And a reference surface 3 in the form of a square tube corresponding to
3, a flat portion 34, an optical surface forming portion 35, an optical surface 36, and a flange portion 37 are provided. The press optical element 3
Reference numeral 1 denotes a spherical mirror, an elliptical mirror, a parabolic mirror, an aspherical mirror, a free-form surface mirror, or the like as in the first embodiment, and a concave mirror from the viewpoint of the optical configuration. .

FIG. 12 is a block diagram of an image forming apparatus using the above-described press optical element 31. A collimator lens 42 and a polygon mirror 43 are sequentially arranged in the traveling direction of the laser beam L emitted from the semiconductor laser light source 41. Laser beam L reflected by polygon mirror 43
The above-described press optical element 31 is arranged in the traveling direction of. A photoconductor 44 is arranged in the traveling direction of the laser beam L reflected by the press optical element 31.

An electric signal carrying information on characters and images is
When input from a host computer (not shown) to the interface controller, the interface controller processes the electric signal. Then, the semiconductor laser light source 41
Drives a laser drive circuit (not shown) according to the output signal of the interface controller, and emits a laser beam L.

The laser beam L emitted from the semiconductor laser light source 41 is condensed by a collimator lens 42 and reflected by a reflecting surface of a rotating polygon mirror 43. The laser beam L reflected by the polygon mirror 43 is reflected by the press optical element 31, and enters the rotating photoconductor 44 while scanning in the axial direction. The photoreceptor 44 is uniformly charged by the action of a charger (not shown), and the charge in the portion where the laser beam L is incident is attenuated, and the charge in the portion where the laser beam L is not incident remains. As a result, an electrostatic latent image corresponding to ON / OFF of the semiconductor laser light source 41 is generated on the photoconductor 44. In this image forming apparatus, since the press optical element 31 is used instead of the conventional spherical lens and toric lens, it is possible to significantly reduce costs and reduce the size.

FIG. 13 is a plan view of a press optical element 51 according to the third embodiment, and FIG. 14 is a cross-sectional view. The press optical element 51 is a concave mirror, and has the same steps as those of the first embodiment. Being manufactured. The press optical element 51 includes the first
Cylindrical reference portion 12, reference surface 13, flat portion 14, optical surface forming portion 15, optical surface 16, flange portion 1 of the embodiment
7, a projection-like reference portion 52 and a reference surface 5 respectively corresponding to
3, a flat portion 54, an optical surface forming portion 55, an optical surface 56, and a flange portion 57 are provided. Three reference portions 52 are formed at equal intervals on the same circumference, and three reference surfaces 53 are provided on the same circumference.

In the third embodiment, the same effects as in the first embodiment can be achieved. In addition, the reference part 52 is 3
However, it goes without saying that there is no problem with four or more.

[0044]

As described above, claims 1, 3 and 4
In the press optical element according to (1), since a reference portion for assembling into an optical device is formed by drawing, there is no occurrence of cuts, burrs, returns, and the like. Therefore, it is possible to form the optical surface without being affected by chips, burrs, return, etc., and to incorporate the optical surface into the optical device. Can be incorporated stably. Further, the rigidity of the optical surface can be improved by the reference portion, and the accuracy of the optical surface can be stabilized when the optical surface is incorporated in the optical device.

In the pressed optical element according to the second aspect, the fitting length to the optical device can be increased, and the inclination and eccentricity of the optical surface can be suppressed remarkably.

In the pressed optical element according to the fifth and sixth aspects, the reflectance of the optical surface can be ensured by the second soft metal substrate, and the rigidity of the second soft metal substrate is supplemented by the first soft metal substrate. Therefore, the precision of the optical surface can be improved. Further, the cost of the first soft metal substrate can be reduced, so that the cost of the metal plate can be suppressed.

In the pressed optical element according to the seventh aspect, it is possible to prevent oxidation, corrosion and the like of the second soft metal substrate having high purity, and to improve weather resistance.

In the method for manufacturing a pressed optical element according to the eighth aspect, since the metal plate is sheared after forming the optical surface, the optical surface is not affected by the shearing, and the precision of the optical surface can be improved. In addition, it is possible to suppress eccentricity with respect to the optical device.

The displacement information detecting device according to the ninth aspect can detect rotation information and movement information with high accuracy.

Since the image forming apparatus according to the tenth aspect does not use the conventional spherical lens and toric lens, the cost can be reduced and the size can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view of a first embodiment of a press optical element.

FIG. 2 is a sectional view.

FIG. 3 is a composition diagram of a metal plate.

FIG. 4 is a composition diagram of a metal plate.

FIG. 5 is a manufacturing process diagram of a pressed optical element.

FIG. 6 is an explanatory view of tilt and eccentricity when a press optical element is incorporated into a normal part to be assembled.

FIG. 7 is an explanatory diagram of an error when manufacturing a press optical element.

FIG. 8 is a cross-sectional view of a state where the press optical element is incorporated in a thin assembly part.

FIG. 9 is a cross-sectional view of a displacement information detecting device using a press optical element.

FIG. 10 is a plan view of a press optical element according to a second embodiment.

FIG. 11 is a sectional view.

FIG. 12 is a configuration diagram of an image forming apparatus using a press optical element.

FIG. 13 is a plan view of a third embodiment of the press optical element.

FIG. 14 is a sectional view.

FIG. 15 is a sectional view of a conventional press optical element.

FIG. 16 is a manufacturing process diagram of a conventional pressed optical element.

FIG. 17 is an explanatory diagram of an error in manufacturing a conventional pressed optical element.

FIG. 18 is an explanatory view of tilt and eccentricity when a conventional press optical element is incorporated in a part to be assembled.

FIG. 19 is an explanatory diagram of an operation when a conventional press optical element is incorporated in a part to be assembled.

[Explanation of symbols]

 11, 31, 51 Press optical element 12, 32, 52 Reference portion 13, 33, 53 Reference surface 14, 34, 54 Flat portion 15, 35, 55 Optical surface forming portion 16, 36, 56 Optical surface 17, 37, 57 Flange 18a, 18b Tie bar 19a, 19b Space 21 Base 22 Light source 23 Light receiving element 24 Lens system 25 Optical scale 26 Lattice 27 Rotation axis 28 Frame 41 Semiconductor laser light source 42 Collimator lens 43 Polygon mirror 44 Photoconductor A Metal plate A1 First Aluminum substrate A2 Second aluminum substrate A3 Glassy film L Laser beam S, S 'Assembly part

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 AA01 AA39 BB21 CC21 FF51 GG06 GG07 HH06 JJ00 LL04 LL15 LL19 LL28 LL42 2H042 DC08 DC11

Claims (10)

[Claims] 1. A press optical element formed by pressing a metal plate and having an optical surface usable for a reflection optical system, wherein a reference portion for assembling into an optical device is formed by drawing. Optical element. 2. In a pressed optical element formed by pressing a metal plate and having an optical surface usable for a reflection optical system, the length of a reference portion in the optical axis direction when incorporated into an optical device is set to the length of the metal plate. A pressed optical element characterized by having a thickness greater than the thickness. 3. The press optical element according to claim 1, wherein an outer peripheral portion of the reference portion has a cylindrical or rectangular tube shape. 4. The press optical element according to claim 1, wherein the reference portion is a projection divided into three or more. 5. The semiconductor device according to claim 1, wherein the metal plate comprises a first soft metal substrate, and a second soft metal substrate provided on the first soft metal substrate and having a higher purity than the first soft metal substrate. The pressed optical element according to claim 1 or 2, wherein: 6. The pressed optical element according to claim 5, wherein said soft metal substrate is an aluminum substrate. 7. The press optical element according to claim 5, wherein a silicon dioxide-based film is applied on the second soft metal substrate. 8. A method for manufacturing a pressed optical element comprising a metal plate pressed and having an optical surface usable for a reflection optical system, comprising a step of shearing the metal plate after forming the optical surface. The manufacturing method of the press optical element characterized by the above-mentioned. 9. A displacement information detecting device for detecting rotation information and movement information of a displaced object by utilizing diffraction of a light beam, comprising the press optical element according to any one of claims 1 to 7. A displacement information detecting device, characterized in that: 10. An image forming apparatus for forming an image by scanning and exposing a light beam on a photoreceptor, wherein the image forming apparatus includes the press optical element according to any one of claims 1 to 7. Image forming apparatus.