JPH0821965A - Variable aperture diaphragm image-formation optical device - Google Patents

Abstract

PURPOSE:To provide a variable aperture diaphragm image-formation optical device capable of easily setting the converging diameter of a luminous flux to desired shape and size and preventing light quantity from lowering. CONSTITUTION:This device is provided with a deformed mirror type optical modulation element 9 having a reflection flat surface formed out of plural minute mirrors which can be deflected, and deflecting the luminous flux made incident on the reflection flat surface to 1st and 2nd directions for every minute mirror at a specified position, in an image-formation optical system constituted of a semiconductor laser 1, a collimator lens 2, an aperture diaphragm 3, a cylindrical lens 4, a rotary polygon mirror 5 and a scanning lens system 6, which are successively disposed on an optical path where the luminous flux projected from the laser 1 passes, and, it has a control means adjusting the range of the minute mirror generating effective reflected light in the case of setting reflected light from the minute mirror deflected in the 1st direction as the effective reflective reflected light in the image-formation optical system by controlling the reflection angle of a each minute mirror.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming optical device used in a laser printer, a camera, etc., and more particularly to an aperture stop variable image forming optical device capable of changing the stop diameter of a light beam.

[0002]

2. Description of the Related Art As an aperture stop variable means capable of changing the stop diameter of a light beam, there is a blade stop used in cameras and the like. This blade diaphragm is for varying the diaphragm diameter of a light beam by mechanically controlling a plurality of blade plates of a predetermined shape, and forming an opening by the plurality of blade plates,
By adjusting the area of the formed opening by rotating and moving each blade, the aperture diameter of the light flux is adjusted.

In a conventional aperture diaphragm variable imaging optical device using such a blade diaphragm, for example, the spot diameter of the light flux imaged on the surface of a photosensitive member such as a laser printer is
By adjusting the opening area with the blade diaphragm, the diameter is adjusted to a predetermined shape and size.

Further, recently, instead of the above-mentioned blade diaphragm, an aperture diaphragm variable image forming optical device using a liquid crystal shutter that uses the polarization of light to perform the function of an optical shutter has been proposed. In the aperture stop variable imaging optical device using this liquid crystal shutter, the aperture diameter of the light flux is adjusted by electrically controlling the light transmitting portion of the liquid crystal shutter.

[0005]

However, the above-described conventional aperture stop variable imaging optical device has the following problems, respectively.

In an aperture diaphragm variable image forming optical device using a blade diaphragm, since a plurality of blade plates form an opening, the number of blade plates is reduced when trying to make the shape of the opening close to a circle. However, there is a problem that the diaphragm mechanism becomes complicated and the diaphragm mechanism becomes complicated.

Further, this aperture diaphragm variable image forming optical device has a problem that durability is lacking because each blade plate rubs when the blade plate mechanically rotationally moves.

In an aperture stop variable imaging optical device using a liquid crystal shutter, the light incident on the liquid crystal shutter always passes through a pair of polarizing plates, so that the light passing through the liquid crystal shutter is polarized and the amount of light is reduced. However, there is a problem that the absolute light amount of the device is reduced. In addition to the decrease in light quantity due to the polarizing plate, the liquid crystal shutter is accompanied by the decrease in light quantity due to the decrease in the transmittance due to the substrate material (glass etc.). There is a problem that there is a large loss.

An object of the present invention is to make it possible to easily make the aperture diameter of a light beam into a desired shape and size without complicating the aperture mechanism, and to control the aperture diaphragm variable imaging optical device without reducing the light quantity. To provide.

[0010]

An aperture stop variable imaging optical apparatus according to the present invention has a reflecting plane formed by a plurality of deflectable micromirrors, and a light beam incident on the reflecting plane is reflected by each of the micromirrors. A variable aperture type spatial light modulator for deflecting in the first and second directions for each of them is provided in an image-forming optical system, and the variable aperture-type variable focus optical device comprises a micromirror for deflecting in the first direction. It is characterized in that there is provided control means for adjusting the reflected light as the effective reflected light in the image forming optical system, and adjusting the range of the minute mirrors that generate the effective reflected light by controlling the reflection angle of each of the minute mirrors.

In this case, there may be provided a removing means for removing the reflected light of the minute mirror which is deflected in the second direction from the imaging optical system.

Further, the control means may control the range of the micromirrors deflected in the first direction into a circular shape.

Further, the control means may be one in which the micromirrors deflecting in the first direction are arranged in a mosaic pattern.

[0014]

In the variable aperture diaphragm image-forming optical apparatus of the present invention constructed as described above, a deforming mirror type having a reflecting plane formed by a plurality of deflectable micromirrors is used as means for varying the aperture diameter of the light beam. A light modulation element is used. That is, according to the present invention, the reflection angles of the respective micro mirrors of the deformable mirror type light modulation element are individually controlled, whereby the deflection of the incident light beam is controlled for each micro mirror. Therefore, the reflected light is controlled so that the reflected light is deflected in the first direction, and the reflected light is reflected in the portion where the light to be cut is incident. By controlling so as to be deflected in the direction of 2, the light to be cut can be separated from the light beam incident on the deforming mirror type light modulation element, and thus a light beam having a predetermined shape and size can be formed. It becomes possible.

Further, according to the present invention, the range of the minute mirror deflecting in the first direction can be freely adjusted by the control means, so that the shape and size of the diameter of the light beam reflected from the modified mirror type light modulation element is desired. You can adjust to what you want.

In the above-mentioned invention having the removing means, the reflected light of the minute mirror deflecting in the second direction is removed from the imaging optical system by the removing means, so that stray light is generated in the imaging optical system. It does not enter.

In the present invention described above, in the case where the range of the micromirrors deflecting in the first direction is controlled in a circular shape, the control means makes the range of the micromirrors deflecting in the first direction continuous in a circular shape. It is possible to realize an aperture stop variable imaging optical device having a function almost equivalent to that of a conventional blade stop having high-speed response.

Among the above-mentioned present invention, in the one in which the micromirrors deflecting in the first direction are arranged in a mosaic pattern,
Since the absolute light amount can be controlled without changing the aperture diameter, the absolute light amount can be controlled without changing the depth of focus of the imaging optical system.

[0019]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a sectional view in the main scanning direction showing a schematic configuration of an aperture diaphragm variable imaging optical device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view in the sub-scanning direction of the aperture diaphragm variable imaging optical device shown in FIG.

The aperture stop variable imaging optical device of this embodiment is
As a means for changing the aperture diameter of a light beam, a modified mirror type light modulation element having a reflection plane formed by a plurality of deflectable micromirrors is used. Of the light flux incident on the deformable mirror type light modulation element, the light to be cut when reflected by each micro mirror is removed by changing the reflection angle of the micro mirror at the portion where the light is incident,
The size and shape of the diameter of the imaged light beam is adjusted.

This aperture stop variable imaging optical device includes a semiconductor laser 1, a collimator lens 2, an aperture stop 3 and a deformable mirror type light modulator 9 which are sequentially arranged in a traveling direction of a light beam emitted from the semiconductor laser 1. A cylindrical lens 4 and a rotary polygonal mirror 5, which are sequentially arranged in the traveling direction of the light flux reflected by the deforming mirror type light modulation element 9, and the light flux reflected by the rotary polygonal mirror 5 of the photosensitive drum 8. And a scanning lens system 6 for condensing light on the surface.

In the above aperture diaphragm variable imaging optical device,
The collimator lens 2 converts the light beam emitted from the semiconductor laser 1 into a substantially parallel light beam, and the aperture stop 3 adjusts the cross-sectional size of the light beam, which is converted into the substantially parallel light beam by the collimator lens 2, to a predetermined size. It is a thing. The deformable mirror type light modulation element 9 is for adjusting the light flux adjusted to a predetermined size by the aperture stop 3 to a light flux having a desired size and shape.

The cylindrical lens 4 is a lens which has a positive lens action in the direction of the sub-scanning direction and has no lens action in the direction of the main scanning direction, and the rotary polygon mirror 5 is located at the focal position of the lens. It is arranged so that the reflective surface of is. This cylindrical lens 4
Then, the light flux emitted from the deformable mirror type light modulation element 9 is subjected to a positive lens action only in the sub-scanning direction, and is reflected on the reflecting surface of the rotary polygon mirror 5 (position P in FIGS. 1 and 2). Is imaged in the shape of.

The rotary polygon mirror 5 is a polygon mirror or the like that scans a beam in the main scanning direction, and is rotated at a constant speed in the direction of arrow 5b by a motor (not shown). The rotary polygon mirror 5 deflects and scans the light beam in the main scanning direction.

The scanning lens system 6 is composed of a first lens 6a having a toric surface having different refractive powers in the main scanning direction and the sub-scanning direction, and a second lens 6b made of a spherical lens. The photoconductor drum 8 is arranged so as to come to the focal position of. In this scanning lens system 6,
The light beam deflected and scanned by the rotary polygon mirror 5 is condensed on the photosensitive drum 8, and the scanning linearity (fθ characteristic) is corrected.

In the variable aperture diaphragm image-forming optical device constructed as described above, the deforming mirror type light modulating element 9 is incorporated in the below-mentioned Japanese Patent Laid-Open No. 61-129627 and Japanese Patent Publication No. 3-7862.
A modified mirror type light modulation element as described in JP-A No. 2 and JP-A-58-10714 is used. Hereinafter, the modified mirror type light modulation elements described in these publications will be described.

FIG. 3 is a diagram for explaining the principle of the modified mirror type light modulation element described in each of the above publications.
(A) is sectional drawing which shows the schematic structure of a deformation | transformation mirror type | mold light modulation element, (b) is a top view of the deformation | transformation mirror type | mold light modulation element shown to (a).

The deformed mirror type light modulators described in the above publications are for deflecting the light reflected by the micromirrors by bending the micromirrors made of a metal thin film by the Coulomb force of charges. is there. The structure is as follows.

In the modified mirror type light modulation element, a layer of an insulator 101 is formed on a substrate 100 such as silicon, and an address electrode 102 and a spacer 103 are formed on the layer of the insulator 101.
A bendable micromirror including the flap 104 is formed.

In the above minute mirror, the address electrode 1
02 is provided on the layer of the insulator 101. The flap 104 is a mirror having a substantially quadrangular shape and bent at one end thereof as a fulcrum, and is provided in parallel to the address electrode 102. A spacer 103, which is an insulator, is provided between the address electrode 102 and the flap 104, and the spacer 103 supports the address electrode 102 so that the flap 104 is bendable. The bending of the flap 104 with respect to the address electrode 102 is performed by inducing opposite charges in the address electrode 102 and the flap 104.

Next, how the deformable mirror type light modulation element configured as described above is used in the optical system of this embodiment will be described.

FIGS. 4A and 4B are for explaining the modified mirror type light modulation element 9 used in this embodiment. FIG. 4A is a diagram showing a schematic appearance of the modified mirror type light modulation element 9, and FIG. The figure for demonstrating the deflection | deflection in the micromirror of the deformation | transformation mirror type | mold optical modulation element 9, (c) is an example which deform | transformed the diameter and shape of a light beam by the deflection | transformation of the deformation | transformation mirror type | mold optical modulation element shown to (a). is there.

The modified mirror type light modulation element 9 is shown in FIG.
As shown in FIG. 3, the mirror is a planar reflection mirror in which a plurality of deflectable micromirrors 10 are provided, and the pitch of each micromirror 10 is 25 μm. The reflecting surface of this micromirror is aluminum vapor-deposited and has a reflectance of about 92%. In such a modified mirror type light modulation element 9, the light flux emitted from the collimator lens 2 described above is reflected, and the first optical path to the cylindrical lens 4 described above and the second optical path not to the cylindrical lens 4 are reflected. Is deflected to the optical path.

The deflection in the modified mirror type light modulation element 9 is reflected by bending the reflecting surface of the minute mirror 10 by applying a voltage to the address electrode of the minute mirror 10 of the modified mirror type light modulation element 9. This is done by changing the direction of the luminous flux to be different from the original direction. That is, as shown in FIG. 4B, a voltage is applied to the address electrode of the micromirror 10 to bend its reflection surface, and a light beam incident from the direction A and reflected in the direction B is reflected by the C beam. This is done by reflecting in the direction.

In the present embodiment, the light beam to be cut out of the light beams incident on the above-mentioned modified mirror type light modulation element 9 is controlled by controlling the reflection angles of the minute mirrors located at the portions where the light beams are incident. Of the light flux toward the first optical path, thereby adjusting the shape and size of the diameter of the light flux toward the first optical path from a circular shape to an elliptical shape as shown in FIG. 4 (c), for example.

The inner wall of the aperture stop variable imaging optical apparatus of this embodiment is coated with a paint that absorbs the wavelength range of the light beam emitted from the semiconductor laser 1 and is deflected to the second optical path. The light is absorbed and removed by the coating material that has been applied without reaching the photosensitive drum 8 (removing means).
Further, in the present embodiment, the bending of the reflecting surface of each of the above-mentioned micro mirrors is independently controlled by the control means (not shown), and the range of the micro mirrors that generate the light flux toward the first optical path is adjusted.

Next, the optical operation of the above-mentioned variable aperture stop imaging optical device will be described.

The light beam emitted from the semiconductor laser 1 passes through the collimator lens 2 and becomes a parallel light beam. The collimated light flux passes through the aperture stop 3 to become a light flux having a diameter of the shape and size of the aperture, and then enters the deforming mirror type light modulation element 9. At this time, in the modified mirror type light modulation element 9, each micro mirror 10 is voltage-controlled,
The diameter of the light flux reflected on the first optical path is set to have a predetermined shape and size.

In the light beam incident on the deformable mirror type light modulation element 9, a part of the light beam incident on the deformable mirror type light modulation element 9 having a predetermined shape and size is reflected to the first optical path, The light flux of the other part is reflected to the second optical path.

The light beam reflected on the first optical path enters the cylindrical lens 4 and is linearly imaged on the reflecting surface of the rotary polygon mirror 5 by the cylindrical lens 4. On the other hand, the light flux reflected on the second optical path is absorbed by the paint applied to the inner wall of the imaging optical system device, and is removed without reaching the photoconductor drum 8.

The light beam linearly imaged on the reflecting surface of the rotary polygon mirror 5 is reflected by the reflecting surface of the rotary polygon mirror 5, and the first lens 6a and the second lens 6b of the scanning lens system 6 are reflected.
To be imaged on the surface of the photosensitive drum 8. The imaged spot is reflected on the surface of the photosensitive drum 8 in the main scanning direction (longitudinal direction of the drum) by deflecting and reflecting the light beam incident on the rotary polygon mirror 5 in accordance with the rotation of the rotary polygon mirror 5. ) Move to.

As described above, in the variable aperture diaphragm imaging optical device of the present embodiment, the reflection angles of the respective micro mirrors of the deformable mirror type light modulation element 9 are individually controlled to move toward the cylindrical lens 4. The diameter of the light flux is adjusted to a predetermined shape and size, and as a result, the spot imaged on the surface of the photosensitive drum 8 is adjusted to a predetermined shape and size.

In the above-mentioned aperture stop variable imaging optical device, when the area of the effective reflection portion of the deformable mirror type light modulation element 9 becomes small, the light quantity of the spot imaged on the surface of the photosensitive drum 8 decreases. There is an inconvenience of doing so.
In such a case, the output of the semiconductor laser 1 is controlled in synchronization with the change in the area of the effective reflection portion of the deformable mirror type light modulation element 9, and the light amount of the spot imaged on the surface of the photosensitive drum 8 is controlled. Is made constant.

Next, another embodiment of the variable aperture stop image-forming optical apparatus of the present invention will be described.

FIG. 5 is a schematic configuration diagram of an aperture diaphragm variable imaging optical device according to a second embodiment of the present invention.

The aperture stop variable imaging optical device of this embodiment is
An image forming optical system used in a camera, a video, or the like, in which a deformable mirror type light modulation element 202 is used as a means for varying the aperture diameter of a light beam, as in the case of the first embodiment. . This aperture stop variable imaging optical device includes a first lens group 201 including an objective lens and the like, and a deforming mirror type light modulation element arranged in a traveling direction of a light beam emitted from the first lens group 201. 202, a mirror 203 provided in the traveling direction of the light flux reflected by the modified mirror type light modulation element 202, and a second lens group 204 which is an imaging lens provided via the mirror 203. ing.

In the aperture stop variable imaging optical device,
The modified mirror type light modulation element 202 is the same as the modified mirror type light modulation element 9 of the aperture diaphragm variable imaging optical device of the first embodiment described above, and the incident light flux is reflected by the mirror 203.
To the first optical path to the mirror 203 and the second to the mirror 203
And the optical path of.

That is, in the present embodiment, the first lens group 2 is formed by the deformable mirror type light modulation element 202 provided between the first lens group 201 and the second lens group 204.
Of the light flux emitted from 01, the light to be cut is deflected to the second optical path and removed, and the diameter of the light flux imaged by the second lens is adjusted to a predetermined shape and size.

In the variable aperture optical imaging apparatus of this embodiment, when the diameter of the light flux imaged by the second lens is adjusted as described above, the modified mirror type light modulation element 202 is used. By changing the effective reflection portion of the micro mirror in (3) to a circular shape, it is possible to realize a variable aperture diaphragm imaging optical device having a function substantially equivalent to that of a blade diaphragm having high-speed response.

In the variable aperture imaging optical device described above, the deformable mirror type light modulation element 202 is used as a variable aperture means, but the effective reflection portion of the deformed mirror type light modulation element 202 is changed into a circular shape. If it is changed to a mosaic shape instead, the absolute light amount can be controlled without changing the aperture diameter.

FIG. 6 shows the modified mirror type optical modulator 20.
2A and 2B are diagrams showing an example in which the effective reflection portions of No. 2 are changed into a mosaic shape, (a) shows the effective reflection portions changed into a mosaic shape for each one micromirror, and (b) shows two adjacent micromirrors. The effective reflection portion is changed into a mosaic shape for each.

In the modified mirror type light modulation element 202 of the variable aperture imaging optical device described above, the reflection angle can be controlled independently for each of the micromirrors, and therefore the effective reflection portion of the modified mirror type light modulation element 202 is shown in FIG. a) or FIG. 6 (b)
The absolute light amount can be controlled by changing it into a mosaic shape as shown in FIG.

Moreover, in the above case, since the absolute light quantity can be controlled without changing the aperture diameter, the depth of focus of the imaging optical system does not change. Further, by setting the shape and size of each micro mirror so as not to be constant, it is possible to prevent moire fringes caused by diffraction of light. In this way, the modified mirror type light modulation element 202 can be provided with the function of optical filtering.

[0055]

Since the present invention is configured as described above, it has the following effects.

According to the first aspect of the present invention, as the means for varying the aperture diameter of the light flux, a deforming mirror type light modulation element having a reflecting plane formed by a plurality of deflectable micro mirrors is used, and each micro mirror is used. By controlling the reflection angle of the mirror, you can adjust the aperture diameter of the light flux,
There is an effect that the aperture diameter of the light flux can be easily made into a desired shape without complicating the aperture mechanism.

Furthermore, the adjustment of the diaphragm diameter of the light flux is performed by reflection by each micro mirror, so that there is an effect that the loss of the absolute light amount can be reduced.

According to the second aspect of the invention, the stray light is removed by the removing means, so that a clear image can be formed.

According to the third aspect of the present invention, the control means continuously changes the range of the micromirrors deflecting in the first direction into a circular shape, so that the variable aperture diaphragm image forming optical device having a high-speed response. Is effective.

According to the fourth aspect of the present invention, the absolute light quantity can be controlled without changing the aperture diameter, so that the absolute light quantity can be controlled without changing the depth of focus of the imaging optical system. There is an effect that it is possible to provide a highly functional aperture stop variable imaging optical device having an optical filtering action.

[Brief description of drawings]

FIG. 1 is a cross-sectional view in a main scanning direction showing a schematic configuration of an aperture diaphragm variable imaging optical device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view in the sub-scanning direction of the aperture diaphragm variable imaging optical device shown in FIG.

3A and 3B are diagrams for explaining the principle of the modified mirror type light modulation element described in each publication, FIG. 3A is a sectional view showing a schematic structure of the modified mirror type light modulation element, and FIG. It is a top view of the modification mirror type optical modulation element shown in a).

4A and 4B are diagrams for explaining a modified mirror type light modulation element 9 used in the present embodiment. FIG. 4A is a diagram showing a schematic appearance of the modified mirror type light modulation element 9, and FIG. 4B is a modified mirror type. The figure for demonstrating the deflection | deflection in the micromirror of the light modulation element 9, (c) is an example which deform | transformed the diameter and shape of a light beam by the deflection | transformation of the deformation | transformation mirror type light modulation element shown to (a).

FIG. 5 is a schematic configuration diagram of an aperture diaphragm variable imaging optical device according to a second embodiment of the present invention.

FIG. 6 is a diagram showing an example in which the effective reflection portion of the modified mirror type light modulation element is changed into a mosaic shape, and FIG. 6A is a diagram in which the effective reflection portion is changed into a mosaic shape for each micromirror; In b), the effective reflection portion is changed in a mosaic pattern for every two adjacent micromirrors.

[Explanation of symbols]

 1 Semiconductor Laser 2 Collimator Lens 3 Aperture 4 Cylindrical Lens 5 Rotating Polygonal Mirror 6 Scanning Lens 6a First Lens 6b Second Lens 8 Photosensitive Drum 9 Deformation Mirror Type Light Modulation Element 10 Micro Mirror

Claims (4)

[Claims] 1. A deformable mirror type space having a reflecting plane formed of a plurality of deflectable micromirrors, and deflecting a light beam incident on the reflecting plane in first and second directions for each of the micromirrors. An aperture stop variable imaging optical device comprising a modulation element in an imaging optical system, wherein reflected light of a micro mirror deflecting in the first direction is used as effective reflected light in the imaging optical system. An aperture stop variable imaging optical device, comprising control means for adjusting a range of a micro mirror that generates reflected light by controlling a reflection angle of each of the micro mirrors. 2. The aperture variable aperture image forming optical device according to claim 1, further comprising a removing unit that removes reflected light of a micro mirror deflecting in a second direction from the image forming optical system. Variable aperture optics. 3. The variable aperture diaphragm imaging optical apparatus according to claim 1 or 2, wherein the control means controls the range of the micromirrors deflecting in the first direction to be circular. Aperture stop variable imaging optical device. 4. The variable-aperture-aperture imaging optical device according to claim 1 or 2, wherein the control means arranges the micromirrors that deflect in the first direction in a mosaic pattern. Variable imaging optics.