JPH04320210A - Scanning optical device - Google Patents

Abstract

PURPOSE:To read or form the whole image information with high accuracy by displacing a photoelectric converting means in the direction of the optical axis of a projection system by a driving means in synchronism with the rotating operation of a scanning mirror. CONSTITUTION:The image information is imaged by a projection system on the surface of a photoelectric converting means 12 where plural elements are linearly arranged through a rotatable scanning mirror 6 and the image information is optically scanned through the rotating operation of the scanning mirror 6 and imaged on the surface of the photoelectric converting means 12 in order. A driving means displaces the photoelectric converting means 12 in the direction of the optical axis of the projection system in synchronism with the rotating operation of the scanning mirror 6. Further, the driving means moves the photoelectric converting means 12 so that its photoelectric surface is positioned on the image formation surface where the image information is imaged by the projection system. Therefore, the position of the photoelectric converting element 12, where the photodetecting elements are linearly arranged, in the direction of the optical axis is adjusted corresponding to the rotation position of the scanning mirror 6 to align the photodetection surface of the photoelectric converting element 12 with the equivalent focus of a projection lens.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning optical device, which is capable of enlarging and projecting reduced image information from a microfilm or the like onto a screen surface using a projection system and quickly copying the image information. The present invention relates to a scanning optical device suitable for reader printers and the like.

0002

2. Description of the Related Art In general, a microreader printer enlarges image information recorded on a microfilm using a projection system, and displays it on a display device such as a screen or CRT so that it can be observed externally. The enlarged image is projected onto a photoreceptor such as a photosensitive drum or a light receiving sensor (photoelectric conversion means) such as a CCD to form a copied image.

FIG. 6 is a schematic diagram of the main parts of a conventional scanning optical device for forming a copy image.

In the figure, image information (photographic image) on a microfilm 1 illuminated by an illumination system (not shown) is reflected by a projection lens 2 onto a screen surface (not shown) or a scanning mirror 6 (scanning mirror). Thereafter, it passes through the slit S and is enlarged and projected onto the photosensitive drum D every predetermined width. The scan mirror 6 is arranged in synchronization with the rotation of the photosensitive drum D.
It rotates in the direction of the arrow around its rotation axis 6a (direction perpendicular to the page). When the scanning mirror 6 is at the rotational position of angle α, the portion of the microfilm 1 indicated by the line segment a1 is projected onto the photosensitive drum D, and when the scanning mirror 6 is at the rotational position of angle β and γ, the microfilm 1 is projected onto the photosensitive drum D. Portions of the film 1 indicated by line segments a2 and a3 are projected onto the photosensitive drum D. By rotating the scanning mirror 6 between the angles α and γ and changing the inclination angle, the entire image between the line segments a1 and a3 of the microfilm 1 is scanned, and this is exposed to light that rotates at a constant speed of V0. The images are sequentially enlarged and projected onto the drum D, thereby forming the entire image of the image information.

FIG. 7 is a schematic diagram of the main parts of a conventional digital type copying apparatus. In the figure, 1 is microfilm, 2
is an imaging lens, which enlarges and projects the microfilm 1 onto the surface of the line sensor 12 via a scanning mirror 6 and a mirror 10. A condenser lens 3 condenses the light beam from the illumination lamp 4. 5 is a lamp reflecting mirror. 13 is a digital printer (recording means), and 14 is a liquid crystal display board (display means).

Image information on the microfilm 1 illuminated by an illumination section consisting of a condenser lens 3, an illumination lamp 4, a lamp reflector 5, etc. is transferred onto the line sensor 12 surface by an imaging lens 2 via a scanning mirror 6 and a mirror 10. It is enlarged and projected. At this time, the scanning mirror 6 optically scans one surface of the microfilm. In the line sensor 12 installed on the imaging surface of the imaging lens 2, a plurality of light receiving elements are arranged in a direction perpendicular to the plane of the paper in FIG. The microfilm 1 is scanned in the sub-scanning direction by rotating the scan mirror 6, and further, the microfilm 1 is scanned in the main scanning direction by the self-scanning of the line sensor 12. As a result, image information on the microfilm 1 is read two-dimensionally by the line sensor 12 and converted into an electrical signal.

[0007] 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 requesting a hard copy (not shown) is pressed by the operator, the data will be sent to the digital printer 1 through the interface.
3 will be printed on paper. If the switch requesting a hard copy is not pressed, the image is displayed on the liquid crystal display board 14.

When outputting on paper using the digital printer 13, the photosensitive drum D explained in FIG. 6 is connected to the line sensor 1.
2, and the scanning principle itself remains unchanged. The difference is that the rotation speed of the scan mirror 6 is synchronized by the copying process speed of the photosensitive drum built into the digital printer, and the image information generated by the scanning light beam does not directly reach the photosensitive drum, but instead is sent to the line sensor. The information from the computer to the digital printer is transmitted using electrical signals.

[0009] The copying process in a digital printer is already known, and a detailed explanation of its configuration will be omitted.

0010

In the conventional scanning optical device as shown in FIG. The equivalent projection surface becomes a curved surface C, and this equivalent projection surface C separates from the equivalent focal plane H, which is the imaging surface for the projection lens 2.

For example, the points on the equivalent projection plane C of the portions indicated by line segments a1 and a3 of the microfilm 1 become points C1 and C3, which are deviated from the equivalent focal plane H by distances ΔC1 and ΔC3.

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

One way to solve this problem is to make the conjugate length sufficiently long to reduce the rotation angle of the scan mirror 6, thereby reducing the deviation amounts ΔC1 and ΔC3 to a level that poses no practical problem. It will be done. however,
In this case, there is a problem that the microreader printer becomes larger.

Another method is to provide an optical path changing mirror in the middle of the light beam traveling from the scan mirror 6 to the photosensitive drum D, and to correct the optical path length by slightly shifting the position of the optical path changing mirror. However, this method has the problem that it is very difficult to shift the mirror without changing its inclination so as not to disturb the scanning optical path, and the vibrations that occur during the shift greatly shake the projected image, making it easy to cause synchronization blur. be.

Furthermore, there is a method to correct barrel distortion by imparting pincushion aberration to the projection lens in advance, but there are problems such as pincushion distortion remaining in the reader system and the inability of zoom lenses to handle all magnifications. . These problems are exactly the same in the scanning optical device shown in FIG.

The present invention adjusts the position in the optical axis direction of a photoelectric conversion element having a plurality of light receiving elements arranged in one dimension according to the rotational position of the scan mirror, so that the light receiving surface of the photoelectric conversion element is always aligned with the equivalent of the projection lens. It is an object of the present invention to provide a scanning optical device that is positioned at a position substantially equal to the focal plane H, thereby making it possible to read or form the entire image information with high precision.

[0017]

[Means for Solving the Problems] The scanning optical device of the present invention forms an image of image information using a projection system via a rotatable scanning mirror onto a photoelectric conversion means surface in which a plurality of elements are arranged in a one-dimensional direction. At the same time, by rotating the scanning mirror,
In a scanning optical device that optically scans the image information and sequentially forms images on the surface of the photoelectric conversion means, the photoelectric conversion means is moved in the optical axis direction of the projection system by a driving means in synchronization with the rotating operation of the scanning mirror. It is characterized by being displaced to .

In particular, the driving means is characterized in that it moves the photoelectric conversion means so that its photocathode is located on the imaging plane of image information by the projection system.

[0019]

Embodiment FIG. 1 is a schematic diagram of a main part of Embodiment 1 of the present invention. In the figure, numeral 1 is a microfilm on which image information is recorded in a reduced size. 2 is an imaging lens, which transfers the image information of the microfilm 1 to a scanning mirror 6 and an optical path changing mirror 1.
The image is enlarged and projected onto photoelectric conversion means 12, which is a line sensor, through 0.

One scan mirror 6 rotates around a rotation axis 6a, thereby optically scanning one surface of the microfilm.

Reference numeral 15 denotes an optical path length correction cam, which is fitted onto the camshaft 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 the timing belt 18.
It is driven by a drive timing pulley 17 fixed to the.

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 onto the rotating shaft 6a, meshes with the worm gear 24, and transmits rotational force 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. 25 is 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 vertical position of the line sensor 12 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, it is not necessary that there be two optical path length correction cams 15, and it is sufficient to use one or a plurality of three or more, as long as all the phases are aligned.

Although a keyway is used in this embodiment to align the phase of the optical path length correction cam 15, the camshaft 23
It may also be one that is integrally ground.

In FIG. 1, the line sensor 12 is connected to the optical path length correction cam 1 using a compression spring 21 in order to perform more stable optical path length correction.
5 side, thereby accurately tracing the profile of the optical path length correction cam 15.

A driven timing pulley 16 provided at the end of the camshaft 23 is rotated by a driving pulley 17 attached to the rotating shaft of the scan mirror 6 via 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 scanning angle of the scan mirror 6 is set to 10
If the cam profile has one period of 60 degrees, the pitch diameter ratio of the driving pulley 17 and the driven pulley 16 is 6:1.

FIG. 2 shows a detailed view of the optical path length correction cam 15.

FIG. 2 shows the cam angle when the scan mirror 6 is at a neutral position, that is, at a position where the optical axis center is projected onto which the equivalent projection plane C and the equivalent focal plane H coincide. 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 away from the equivalent projection plane C toward the edge of the image. 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 center of the optical axis. Line sensor 12
is lifted by the optical path length correction cam 15, and reaches the maximum lift amount at the center of the optical axis. As the optical scan further advances and moves away from the optical axis center, the line sensor 12 approaches the base circle of the optical path length correction cam 15, and when the optical scan reaches another end of the image, the line sensor 12 again moves away from the optical path length correction cam 15. is tangent to the base circle of.

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

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

Furthermore, according to this embodiment, even if minute vibrations occur when the line sensor is moved in the optical axis direction, the minute vibrations will be smaller than in a method in which an optical path changing mirror provided in the middle of the optical path is moved. When the direction is broken down 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 will deviate in both the vertical and parallel vectors due to the angle of reflection, resulting in synchronization shake. In the case of a line sensor, it is only necessary to pay attention to the vector component perpendicular to the optical axis, so the effect on synchronization blur is much smaller.

FIG. 3, FIG. 4, and FIG. 5 each show a second embodiment of the present invention.
, 3 and 4 are schematic diagrams of main parts. In the figure, elements that are the same as those shown in FIG. 1 are given the same negative numbers. In the second embodiment shown in FIG. 3, the rotation operation of the scan mirror 6 and the driving of the line sensor 12 are performed using an electrical synchronization means 31. For this reason, a new motor 2 is used as a driving means for the line sensor 12.
There are 6.

That is, in the first embodiment described above, power was mechanically extracted from the scan motor 19 that drives the scan mirror 6 to correct the position of the line sensor 12, but in this embodiment, the scan mirror is electrically 6 and the optical path length correction cam 15 are synchronized and driven by separate motors (19, 26). In the first embodiment, the scan mirror 6 and the optical path length correction cam 15 are constructed only by a pulley and a belt, which is inexpensive and mechanically guarantees the accuracy requirements. The degree of freedom in arrangement is reduced, and more space is required for the belt.

Therefore, in this embodiment, a more compact scanning optical device is achieved by using electrical 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 driving means for the line sensor 12. The rotation of the scan mirror 6 is read by a rotary encoder 28, and the position of the line sensor 12 is adjusted by driving the piezoelectric element 27 in electrical synchronization using the signal from the rotary encoder 28.

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

Here, a piezoelectric element has the property of deforming itself when a voltage is applied to it, and it is also known that it responds linearly to a certain voltage change, and is particularly suitable for minute displacement control systems. suitable for

In the first and second embodiments described above, in order to correct the optical path length using a motor as a driving means, a "cam" that converts rotation into a slide is used, but in this embodiment, direct displacement by a piezoelectric element is used. Because it uses a motor, the drive unit itself is extremely compact, and it also has the advantage of not producing noise like a motor.

However, since the amount of displacement of the piezoelectric element itself is extremely small, ranging from several tens of microns to several hundred microns, in this embodiment, it is used in a stacked state as shown in FIG. The displacement is amplified and used.

In the fourth embodiment shown in FIG. 5, the line sensor 12 is driven using two piezoelectric elements 27A, 27B and a lever 29.
The other configurations are substantially the same as the third embodiment shown in FIG.

That is, in this embodiment, the piezoelectric elements are not stacked, but a lever is used to amplify the displacement. Furthermore, as a feature of this embodiment, two piezoelectric elements of 27A are used.
, 27B, the line sensor 12 can be tilted and displaced.

The average displacement of the piezoelectric elements 27A and 27B becomes the total displacement of the line sensor 12, and the piezoelectric element 2
The displacement difference between the piezoelectric element 7A and the piezoelectric element 27B becomes the inclination of the line sensor 12.

This is to correct the angular change in the light beam incident on the line sensor that occurs when one mirror is rotated and scanned. A light beam that is incident perpendicularly to the line sensor at the center of the optical axis is also incident at the edge of the image at an angle corresponding to the angle of view. There is no problem if the line sensor is a theoretical point, but in reality it is a surface with a certain minute area, so there may be a problem of variations in sensitivity depending on the angle of incidence.

Further, a slit may be provided just before the line sensor 12 in order to prevent the influence of stray light other than the projection light beam or halation. In this case as well, if the incident angle changes and the slit is widened to match the maximum value to prevent vignetting, the effect of the slit will be reduced accordingly.

Therefore, by using the two piezoelectric elements 27A and 27B to correct the optical path length and at the same time correct the inclination of the line sensor, it is possible to read a clearer image light beam.

[0048]

According to the present invention, the position in the optical axis direction of the photoelectric conversion element in which a plurality of light receiving elements are arranged in one dimension is adjusted according to the rotational position of the 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 that is free from defocus and provides good image quality without distortion.

[Brief explanation of drawings]

FIG. 1 A perspective view of Embodiment 1 of the scanning optical device of the present invention.

[Figure 2] Detailed explanatory diagram of the optical path length correction cam in Figure 1

[Figure 3
] Perspective view of Embodiment 2 of the present invention

FIG. 4 Schematic diagram of main parts of Example 3 of the present invention

[Figure 5] Schematic diagram of main parts of Example 4 of the present invention

[Figure 6] Theoretical diagram of a conventional rotating scanning optical system using a single mirror

[Figure 7] Explanatory diagram of a digital scanning device using a conventional rotary scanning optical system using a single mirror and a line sensor

[Explanation of symbols]

1 Microfilm 2 Imaging lens 3 Condenser lens 4 Illumination lamp 5 Lamp reflector 6 Scanning mirror 6a Rotating shaft 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 Driven 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 drive motor 27 Piezoelectric element 28 Rotary encoder 29 Lever 29a Fulcrum

Claims (2)

[Claims] 1. Image information is formed by a projection system via a rotatable scanning mirror onto a photoelectric conversion means surface in which a plurality of elements are arranged in a one-dimensional direction, and by rotating the scanning mirror, In a scanning optical device that optically scans the image information and sequentially forms images on the surface of the photoelectric conversion means, the photoelectric conversion means is moved in the optical axis direction of the projection system by a driving means in synchronization with the rotating operation of the scanning mirror. A scanning optical device characterized in that the scanning optical device is displaced by. 2. A scanning optical device according to claim 1, wherein said driving means moves said photoelectric conversion means so that its photocathode is positioned on an imaging plane of image information by said projection system.