JP2982371B2 - Scanning optical device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning optical apparatus, and more particularly to a micro optical system capable of enlarging and projecting reduced image information such as a microfilm onto a screen surface by a projection system and quickly copying the image information. The present invention relates to a scanning optical device suitable for a reader printer or the like.

[0002]

2. Description of the Related Art Generally, a micro-reader printer enlarges image information recorded on a reduced microfilm by a projection system, displays the enlarged image information on a display device such as a screen or a CRT, and enables external observation. The enlarged image is projected on a light receiving sensor (photoelectric conversion means) such as a photosensitive drum or a CCD as a photoreceptor, so that a copy image is formed.

FIG. 6 is a schematic view of a main part of a conventional scanning optical device for forming a copied image.

In FIG. 1, image information (photographic image) on a microfilm 1 illuminated by an illumination system (not shown) is reflected by a projection lens 2 on a screen surface (not shown) or a scanning mirror 6 (scan mirror). Thereafter, the image is enlarged and projected on the photosensitive drum D at predetermined intervals through the slit S.
The scan mirror 6 is synchronized with the rotation of the photosensitive drum D,
It rotates in the direction of the arrow about its rotation axis 6a (perpendicular to the paper). When the scan mirror 6 is at the rotation position of the angle α, the portion indicated by the line segment a ₁ of the microfilm 1 is
When the image is projected on the photosensitive drum D and the scan mirror 6 is at the rotation positions of the angles β and γ, the portions indicated by the line segments a ₂ and a ₃ of the microfilm 1 are projected on the photosensitive drum D. By rotating the scan mirror 6 between the angles α to γ and changing the inclination angle in this manner, the entire image between the line segments a _{1 to} a ₃ of the microfilm 1 is scanned, and this is performed at a constant speed V ₀ . The image is sequentially enlarged and projected on the rotating photosensitive drum D, thereby forming an entire image of image information.

FIG. 7 is a schematic view of a main part of a conventional digital copying image apparatus. In the figure, 1 is a microfilm, 2
Denotes an imaging lens, which projects the microfilm 1 on a line sensor 12 via a scanning mirror 6 and a mirror 10 in an enlarged manner. Reference numeral 3 denotes a condenser lens which collects a light beam from the illumination lamp 4. 5 is a lamp reflecting mirror. Reference numeral 13 denotes a digital printer (recording means), and reference numeral 14 denotes a liquid crystal display panel (display means).

The image information of the microfilm 1 illuminated by the illumination unit including the condenser lens 3, the illumination lamp 4, the lamp reflection mirror 5, and the like is transferred onto the line sensor 12 via the scan mirror 6 and the mirror 10 by the imaging lens 2. Is enlarged and projected. At this time, one surface of the microfilm is optically scanned by the scan mirror 6. The line sensor 12 installed on the image forming surface of the image forming lens 2 has a plurality of light receiving elements arranged in a direction perpendicular to the sheet of FIG. The microfilm 1 is scanned in the sub-scanning direction by rotating the scan mirror 6, and the microfilm 1 is further scanned in the main scanning direction by the self-scanning of the line sensor 12. Thus, the image information of the microfilm 1 is two-dimensionally read by the line sensor 12 and converted into an electric signal.

The image information replaced by the electric signal is amplified by an amplifier, subjected to predetermined image processing, and temporarily recorded in an image memory. At this time, if a switch for requesting a hard copy (not shown) is pressed by an operator operation, the digital printer 1 passes through the interface.
3 is output on paper. If the switch for requesting a hard copy is not pressed, an image is displayed on the liquid crystal display panel 14.

When the digital printer 13 outputs paper, the photosensitive drum D described with reference to FIG.
The scanning principle itself is not changed. What is different is that the rotation speed of the scan mirror 6 is synchronized with the copying process speed of the photosensitive drum built in the digital printer, and that the image information based on the scanning light flux does not directly reach the photosensitive drum, but a line sensor. From the digital printer to the digital printer.

The copying process in a digital printer is already known, and a detailed description of the configuration will be omitted.

[0010]

As shown in FIG. 6, in the conventional scanning optical apparatus, since the rotation axis 6a of the scanning mirror 6 is arranged at a fixed position, the light is projected onto the photosensitive drum D by the projection lens 2. The equivalent projection plane becomes a curved surface C, and this equivalent projection plane C is separated from an equivalent focal plane H which is an imaging plane for the projection lens 2.

For example, points on the equivalent projection plane C at portions indicated by line segments a ₁ and a ₃ of the microfilm 1 are points C ₁ and C ₃
And a shift of the distances ΔC ₁ and ΔC _{3 from} the equivalent focal plane H occurs.

For this reason, when the scan mirror 6 scans at an angle other than the position β in FIG. 6, the focus position shifts and a magnification error occurs, resulting in defocusing of the copied image and barrel-shaped image distortion. There was a problem.

As a method of solving such a problem, a sufficiently long conjugate length is used to reduce the rotation angle of the scan mirror 6 and to reduce the deviation amounts ΔC ₁ and ΔC ₃ to such a degree that there is no practical problem. Can be considered. However, in this case, there is a problem that the micro reader printer becomes large.

As another method, there is a method in which an optical path changing mirror is provided in the middle of the light beam from the scan mirror 6 to the photosensitive drum D, and the position of the optical path changing mirror is slightly shifted to correct the optical path length. However, in this method, it is very difficult to shift the mirror without changing the tilt of the mirror so as not to disturb the scanning optical path, and the vibration occurring during the shift greatly shakes the projected image and tends to cause synchronization blur. is there.

There is also a method of correcting barrel distortion by giving pincushion aberration to the projection lens in advance. However, pincushion distortion remains in the reader system, and zoom lenses cannot cope with all magnifications. . These problems are exactly the same in the scanning optical device shown in FIG.

According to the present invention, the position in the optical axis direction of a photoelectric conversion element in which a plurality of light receiving elements are arranged in a one-dimensional direction is adjusted according to the rotational position of a scan mirror, and the light receiving surface of the photoelectric conversion element is always equivalent to a projection lens. It is an object of the present invention to provide a scanning optical device which is set at a position substantially equal to the focal plane H so that the entire image information can be read or formed with high accuracy.

[0017]

A scanning optical device according to the present invention forms an image of image information on a photoelectric conversion means surface on which a plurality of elements are arranged in a one-dimensional direction via a scanning mirror rotatable by a projection system. In addition, in a scanning optical device that optically scans the image information and sequentially forms an image on the photoelectric conversion unit surface by rotating the scanning mirror, a driving unit synchronizes with the rotating operation of the scanning mirror. It is characterized in that the photoelectric conversion means is displaced in the direction of the optical axis of the projection system.

In particular, the driving means moves the photoelectric conversion means so that its photoelectric surface is located on an image forming plane of image information by the projection system.

[0019]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention. In the figure, reference numeral 1 denotes a microfilm on which image information is recorded in a reduced size. Reference numeral 2 denotes an imaging lens, which enlarges and projects image information of the microfilm 1 onto a photoelectric conversion unit 12 including a line sensor via a scan mirror 6 and an optical path changing mirror 10.

One scan mirror 6 is rotated about a rotation shaft 6a, thereby optically scanning the microfilm 1 surface.

An optical path length correction cam 15 is fitted on the cam shaft 23. Reference numeral 16 denotes a driven timing pulley, which is fixed to one end of the camshaft 23, and is connected to the rotation shaft 6a of the scan mirror 6 via a timing belt 18.
And is driven by a drive timing pulley 17 fixed to the drive timing pulley 17.

Reference numeral 19 denotes a scanning motor, and a worm gear 24 is provided on the output shaft. Reference numeral 20 denotes a reduction gear, which is fitted on the rotating shaft 6a, meshes with the worm gear 24, and transmits the rotating power from the motor 19. The scan mirror 6 is fixed to one end of the rotating shaft 6a, and the drive timing pulley 17 is fixed to the other end. Reference numeral 25 denotes a flat cable.

The line sensor 12 is provided with a guide shaft 22 so as to be slidable in the vertical direction, and the position of the line sensor 12 in the vertical direction is determined by an optical path length correction cam 15 disposed below the line sensor 12. Although two optical path length correction cams 15 are provided in FIG. 1, the number of the optical path length correction cams 15 does not necessarily have to be two.

In this embodiment, a keyway is used to make the phase of the optical path length correction cam 15 uniform.
It may be one that is integrally ground.

In FIG. 1, the line sensor 12 is compressed by a compression spring 21 so that the optical path length correction cam 1 can be more stably corrected.
5, which accurately traces the profile of the optical path length correction cam 15.

The driven timing pulley 16 provided at the end of the camshaft 23 is rotated by a driving pulley 17 attached to a rotating shaft of the scan mirror 6 by a timing belt 18. At this time, the driving pulley 17 and the driven pulley 1
The radius ratio of 6 is determined by the scanning angle of the scan mirror 6 and the cam profile of the optical path length correction cam 15.

For example, if the scan angle of the scan mirror 6 is 10
If the cam profile is 60 ° per cycle, the pitch diameter ratio between the driving pulley 17 and the driven pulley 16 is 6: 1.

FIG. 2 is a detailed view of the optical path length correction cam 15. As shown in FIG.

FIG. 2 shows the cam angle at the position where the scan mirror 6 is in the neutral position, that is, the position where the equivalent projection plane C and the equivalent focal plane H are projected at the center of the optical axis. As shown in FIG. 6, when the position of the line sensor 12 is set based on the optical path length at the center of the optical axis, the equivalent focal plane H becomes farther from the equivalent projection plane C toward the image end. For this reason, the line sensor 12 must be separated from the film surface 1.

That is, when the scan mirror 6 is projecting a certain image end, the line sensor 12 is in contact with the base circle of the optical path length correction cam 15, and the scan mirror 6 rotates toward the optical axis center. Line sensor 12 as it goes
Is lifted by the optical path length correction cam 15, and has a maximum lift amount at the center of the optical axis. Further, as the optical scanning further advances and moves away from the center of the optical axis, the line sensor 12 approaches the base circle of the optical path length correction cam 15, and when the optical scanning reaches another image end, the line sensor 12 again sets the optical path length correction cam 15. Touches the base circle of

The cam profile of the optical path length correction cam 15 can be determined by an optical drawing and an arbitrary cam rotation angle.

In this embodiment, the scan mirror 6 is
The optical path in the sub-scanning direction is corrected by displacing the line sensor 12 in the optical axis direction in synchronization with the rotation of the microfilm 1, and a good projection image is formed on the surface of the line sensor 12 over the entire microfilm 1. Thereby, it is possible to form an image with good image quality.

Further, according to the present embodiment, even if the micro-vibration occurs when the line sensor is moved in the optical axis direction, the micro-vibration is smaller than the method of moving the optical path changing mirror provided in the optical path. When the direction is decomposed into a vector parallel to the optical axis and a vector perpendicular to the optical axis, in the case of a mirror, the optical axis is displaced for both the vertical vector and the parallel vector due to the reflection angle, but synchronous vibration occurs, In the case of a line sensor, it is only necessary to pay attention to the vector component perpendicular to the optical axis.

FIG. 3, FIG. 4, and FIG. 5 are schematic views of main parts of the second, third, and fourth embodiments of the present invention, respectively. In the figure, the same elements as those shown in FIG. 1 are denoted by the same negative numbers. Embodiment 2 of FIG.
In this example, the rotation operation of the scan mirror 6 and the driving of the line sensor 12 are performed by using an electric synchronization means 31. For this reason, a motor 26 is newly provided as a driving unit of the line sensor 12.

That is, in the first embodiment, the power is mechanically extracted from the scanning motor 19 for driving the scan mirror 6 to correct the position of the line sensor 12, but in this embodiment, the scan mirror is electrically connected. 6 and the optical path length correction cam 15 are synchronized and driven by separate motors (19, 26). In the first embodiment, only the pulley and belt connecting the scan mirror 6 and the optical path length correction cam 15 are used, and the demand for accuracy is mechanically guaranteed at a low cost. The degree of freedom in arrangement is reduced, and space for the belt is required.

In this embodiment, a more compact scanning optical device is achieved by using an electric synchronization means 31 such as a pulse motor or a rotary encoder.

In the third embodiment shown in FIG. 4, a piezoelectric element 27 is used as a driving means of the line sensor 12. The rotation of the scan mirror 6 is read by the rotary encoder 28, and the position of the line sensor 12 is adjusted by driving the piezoelectric element 27 electrically in synchronization with the signal from the rotary encoder 28.

That is, in this embodiment, the rotary angle of the scan mirror 6 is read by the rotary encoder 28 and the motor 19 for scanning is feedback-controlled to be driven synchronously with a digital printer (not shown). The optical element length correction is performed by operating the provided piezoelectric element 27.

It is known that a piezoelectric element has a characteristic that it deforms itself when a voltage is applied, and that it responds linearly to a certain voltage change. Suitable for.

In the first and second embodiments, a "cam" for converting rotation into a slide is used in order to perform optical path length correction using a motor as a driving means. In this embodiment, however, direct displacement by a piezoelectric element is used. The use of a drive makes it possible to reduce the size of the driving device itself, and has the advantage that it does not emit noise unlike a motor.

However, since the displacement of the piezoelectric element itself is a very small amount of several tens to several hundreds of microns, in this embodiment, the piezoelectric element is used in a laminated state as shown in FIG. The displacement is amplified and used.

In the fourth embodiment shown in FIG. 5, two piezoelectric elements 27A and 27B and a lever 29 are used to drive the line sensor 12.
The other configuration is substantially the same as that of the third embodiment shown in FIG. 29a is a fulcrum of the lever 29.

That is, in the present embodiment, the displacement of the piezoelectric element is amplified using a lever, instead of being stacked. Further, as a feature of this embodiment, two piezoelectric elements 27
A, 27B is that the line sensor 12 can be displaced with an inclination.

The average displacement of the piezoelectric elements 27A and 27B is the total displacement of the line sensor 12, and
The displacement difference between 7A and the piezoelectric element 27B becomes the inclination of the line sensor 12.

This is for correcting a change in the angle of the light beam incident on the line sensor, which occurs when one mirror is rotated and scanned. At the center of the optical axis, a light beam that is perpendicularly incident on the line sensor is also incident at an end of the image at an angle corresponding to the angle of view. Although there is no problem when the line sensor is a theoretical point, there is a possibility that the sensitivity actually varies depending on the incident angle because the line sensor has a certain small area.

A slit may be provided immediately before the line sensor 12 in order to prevent the influence of stray light and halation other than the projection light beam. In this case as well, if the angle of incidence is changed, the effect of the slit is reduced by widening the slit so as not to cause vignetting according to the maximum value.

Therefore, by correcting the optical path length using the two piezoelectric elements 27A and 27B and also correcting the inclination of the line sensor, a clearer image light beam can be read.

[0048]

According to the present invention, the position in the optical axis direction of a photoelectric conversion element in which a plurality of light receiving elements are arranged in a one-dimensional direction is adjusted according to the rotational position of a scan mirror, and the light receiving surface of the photoelectric conversion element is always adjusted. Can be made equal to the equivalent focal plane of the projection lens, and it is possible to achieve a scanning optical device which can obtain good image quality without defocus and without distortion.

[Brief description of the drawings]

FIG. 1 is a perspective view of a scanning optical apparatus according to a first embodiment of the present invention.

FIG. 2 is a detailed explanatory view of the optical path length correction cam of FIG. 1;

FIG. 3 is a perspective view of a second embodiment of the present invention.

FIG. 4 is a schematic diagram of a main part of a third embodiment of the present invention.

FIG. 5 is a schematic diagram of a main part of a fourth embodiment of the present invention.

FIG. 6 is a theoretical explanatory diagram of a conventional rotary scanning optical system using a single mirror.

FIG. 7 is an explanatory diagram of a conventional rotary scanning optical system using a single mirror and a digital scanning device using a line sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microfilm 2 Imaging lens 3 Condenser lens 4 Illumination lamp 5 Lamp reflector 6 Scan mirror 6a Rotation axis 10 Optical path changing mirror 12 Line sensor 13 Digital printer (Recording means) 14 Liquid crystal display board (Display means) 15 Optical path length correction cam 16 Followed Timing Pulley 17 Drive Timing Pulley 18 Timing Belt 19 Scanning Motor 20 Reduction Gear 21 Compression Spring 22 Guide Shaft 23 Camshaft 24 Worm Gear 25 Flat Cable 26 Cam Driving Motor 27 Piezoelectric Element 28 Rotary Encoder 29 Lever 29a

Claims (2)

(57) [Claims] An image is formed on a photoelectric conversion surface on which a plurality of elements are arranged in a one-dimensional direction via a scanning mirror rotatable by a projection system. In a scanning optical apparatus for optically scanning the image information and sequentially forming an image on the surface of the photoelectric conversion unit, the driving unit drives the photoelectric conversion unit in the optical axis direction of the projection system in synchronization with the rotation operation of the scanning mirror. A scanning optical device characterized by being displaced in a direction. 2. The scanning optical apparatus according to claim 1, wherein said driving means moves said photoelectric conversion means such that a photoelectric surface thereof is located on an image forming plane of image information by said projection system.