JPH04165326A - Photoscanning device - Google Patents

Abstract

PURPOSE:To perform photoscanning according to a recording form on an equal velocity linear device or a photorecording medium, such as equal velocity scanning, by disposing a photo guided wave array to convert photobeams so as to match a recording form on a photorecording medium. CONSTITUTION:Through rotation of a rotary mirror 12b composing a multiple reflection mirror 12, photobeams from a light source 11 are multiple-reflected to receive high deflection. Through the deflection, photobeams from the light source 11 enter each photoguide wave passage composing a photoguide wave passage array 14. In which case, since the guided wave passages are arranged on a curve at non-interval, the focus of scanned photobeams is a non-equal velocity. Even when the focus is moved through distortion curve movement, the photobeams enter, in order, each photoguided wave passage at intervals of a specified time. The photobeams entering the photoguided wave passage array 14 are propagated to the photoguided wave passage, and are emitted, in order, from emission ends, arranged on a linear line, at equal intervals of a specified time. This constitution converts non-equal velocity and distortion curve movement of photobeams into equal velocity linear movement.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to optical printers, facsimile machines, laser markers,
This invention relates to improvements in optical scanning devices used in displacement meters, etc.

[Conventional technology]

In recent years, optical printers have been used as computer output devices in place of conventional line printers. Hereinafter, an optical scanning device used in an optical printer will be explained with reference to FIG.

FIG. 5 shows a conventional optical scanning device 50. As shown in FIG. In this optical scanning device 50, a light beam from a light source 51 is made into a parallel beam by a collimating lens 52, and then a condensing lens 52
3, and is scanned at a constant angular speed by a polygon mirror 54 which is rotated at a constant speed by a motor (not shown).

The light beam to be scanned by the means performs approximately uniform circular scanning, but a structure such as the f-θ lens 55 is easy, and
By using an inner linear conversion means using an inexpensive optical system, the scanned light beam can be converted to perform uniform linear scanning. The light beam passing through the f-θ lens 55 is
The light is reflected by a plane reflecting mirror 56 and linearly scanned at a constant speed on a rotating photosensitive drum 60, which is an optical recording medium, along a straight line parallel to its rotation axis. As mentioned above, the recording format of conventional optical printers is uniform speed linear scanning. Note that in this case, since the length of the photosensitive drum 60 in the rotation axis direction is large, it is necessary to increase the scanning distance of the light beam.

However, in the conventional optical scanning device 50, in order to rotate the polygon mirror 54 at a constant speed and high speed, it is necessary to increase the size of the polygon mirror 54 to some extent, increase the weight, and increase the rotational inertia. If the weight of the polygon mirror 54 increases, the motor serving as its drive system must be large and consume a large amount of power, which is undesirable as it increases the size of the device and the running cost.

As a method to compensate for this drawback, a moving magnet method or a moving coil method can be used instead of the motor and polygon mirror 54. Another method is to use a piezoelectric actuator to vibrate and rotate two lightweight reflecting mirrors placed opposite each other at high speed, and to perform optical scanning by injecting a light beam between the reflecting mirrors so as to cause multiple reflections. An optical scanning device has been proposed in which the scanning distance is increased to scan a light beam on a photosensitive drum (Japanese Patent Application Laid-Open Nos. 134726/1982 and 215516/1982). According to this optical scanning device, since it is sufficient to vibrate and rotate a lightweight micromirror at high speed, the drive system for the vibratory rotation is also lightweight;
Moreover, power consumption is also low.

[Problem to be solved by the invention]

However, in the optical scanning device that utilizes multiple reflections of the light beam, the focal locus of the scanned light beam that is scanned by the rotation of the reflecting surface becomes a "distorted curve J."

In order to eliminate this distorted curve, a complex optical system must be used. Therefore, the configuration is easy, and
There was a problem in that it was not possible to perform linear scanning or circular scanning using an inexpensive optical system. Note that the above-mentioned "distorted curve" will be described later.

In addition, when the movement of the minute reflective surface is not continuous rotation in a fixed direction when it is vibrated and rotated by the above drive system, due to problems such as the time response of the drive system, the torque, and the inertia force in the rotation direction of the reflective surface, The focal point of the scanned light beam is not scanned at a constant speed and causes large speed fluctuations, so there is a problem in that it is difficult to perform uniform linear scanning or constant velocity scanning.

The present invention has been made to solve the above-mentioned problems, and even an optical scanning device that utilizes multiple reflections of a light beam between two reflective surfaces can be easily constructed. An object of the present invention is to provide an optical scanning device that can perform, for example, uniform-velocity linear scanning or uniform-velocity scanning using an inexpensive optical system.

[Means to solve the problem]

In order to achieve this object, the optical scanning device of the present invention multiple-reflects a light beam emitted from a light source between two reflecting mirrors placed opposite each other, at least one of which moves slightly, so that the light beam after the multiple reflections is An optical scanning device that optically scans a beam onto an optical recording medium includes an optical waveguide array between the output end of the reflecting mirror and the optical recording medium, and the input end of the optical waveguide array The optical waveguide array is arranged so that the focal locus curve of the light beam is incident thereon, and the output end of the optical waveguide array is arranged so as to match the recording format of the optical recording medium and output the light beam.

[Effect]

In the present invention, a light beam emitted from a light source is incident on two reflecting mirrors placed opposite each other, at least one of which moves slightly, and the light beam after multiple reflections is reflected between the two reflecting mirrors. The light is emitted from the output end of the reflector. The focal locus of the emitted light beam (scanned beam) is a distorted curve, and the moving focal point has speed fluctuations.
If we plot the coordinates of the focal point in space at regular intervals, we get
It is represented as a series of irregularly spaced points arranged on the distorted curve.

By arranging the entrance ports of the individual optical waveguides forming the entrance end of the optical waveguide array at positions corresponding to the individual points of the row of non-uniformly spaced points, the scanned light beam is scanned at regular intervals. are sequentially input to the optical waveguides on each side. The light beam incident on the optical waveguide array is propagated through the individual optical waveguides and exits from the output end of the optical waveguide.
If they are arranged in a straight line at equal intervals, uniform speed linear scanning can be achieved. Similarly, uniform speed scanning can be realized by arranging the exit ports on the circumference at regular intervals, for example.

As described above, the scanned light beam is converted by the optical waveguide array to suit the recording format on the optical recording medium and output.

〔Example〕

An embodiment embodying the present invention will be described below with reference to the drawings.

FIG. 1 shows an optical scanning device used in an optical printer according to the present invention. In FIG. 1, an optical scanning device 10 includes a light source 11 that generates a light beam based on an image signal, a multiple reflector 12 for scanning the light beam from the light source 11, and a laminated piezoelectric actuator that drives the multiple reflector 12. 13a,
13b, and an optical waveguide array 14 in which a large number of optical waveguides for propagating the light beam scanned by the multiple reflection mirror 12 to the photosensitive drum 20 are arranged in rows.

The light source 11 generates a light beam by blinking in response to an electric signal based on image information, and specifically, a laser diode).
A semiconductor light source such as a light emitting diode (LD) or a light emitting diode (LED) is used.

The multiple reflecting mirror 12 includes a fixed mirror 1.2a and a rotating mirror 12b.
, a holding member 12c that holds the fixed mirror 12a, and a rotating mirror 1.
A holding shaft 12 (l) for holding the mirror 2b and rotating it around its central axis.A fixed mirror 12a and a rotating mirror 12b.
The mirror surfaces of are arranged opposite to each other.

The laminated piezoelectric actuators 1.3a and 13b are connected to the holding shaft 1.
A drive source that rotates 2d around its central axis,
As shown in FIG. 1, one or more laminated piezoelectric elements are disposed in sliding contact with the holding shaft 12cl. The expansion and contraction of the laminated piezoelectric element is controlled by voltage control or injection current control, and this expansion and contraction controls the rotation angle of the holding shaft 12d that receives a couple of forces, and as a result, the rotating mirror 12
The rotation angle of b is controlled. Now, when the speed of expansion and contraction of the laminated piezoelectric element is constant, the rotating mirror 12b is rotated at a constant angular speed. Therefore, when the two laminated piezoelectric elements are alternately expanded and contracted at high speed, the rotating mirror 12b vibrates and rotates at high speed with a small rotation angle. Here, oscillating rotation refers to reciprocating rotational movement at a small angle around the rotation axis.

On the downstream side in the direction of propagation of the light beam from the light source 11, there is a light source 11.
A collimating lens 15 is provided that converts the light beam from the light beam into a parallel light beam. Further downstream of the collimator lens 15, a cylindrical lens 16 is provided that condenses the light emitted from the collimator lens 15.

The condensed light beam is incident on the multiple reflector 12 at an incident angle that causes multiple reflections within the multiple reflector 12,
The light is scanned by the rotation of the rotating mirror 12b and is emitted from the multiple reflection mirror. In other words, the light beam focused by the rotation of the rotating mirror 12b is configured to be sequentially incident on each optical waveguide constituting the optical waveguide array 14.

The optical waveguide array 14 is formed by arranging a large number of optical waveguides for propagating the light beam emitted from the light source 11 to the photosensitive drum 20. The input end 14a of the optical waveguide array 14 is formed in a substantially arc shape so as to surround the multiple reflection mirror 12, and the output end 14b is formed in a straight line parallel to the central axis of the photosensitive drum 20. The pestle is placed in close proximity to the pestle.

Here, the "distorted curve" regarding the focal locus described above will be explained based on FIG. 2.

FIG. 2 shows the focal locus 21 of the scanned beam, the optical waveguide array 14, etc. It is well known that the focal locus 21 of the light beam scanned by the multiple reflection mirror 12 always becomes a distorted curve. That is, a "distorted curve" refers to a curve in which the optical axis locus 22 of the scanned beam is not on one plane, and at the same time, the focal locus 21 is not a perfect circle.

Generally, the focal point of the light beam scanned at high speed by the rotating mirror 12b is not scanned at a constant speed, but causes large speed fluctuations. The focal locus 21 of the light beam scanned by the multiple reflection mirror 12 becomes the aforementioned distorted curve, and since the moving focal point has speed fluctuations, plotting the coordinates of the focal point in space at regular intervals will result in the distorted curve. It is represented as a row 23 of irregularly spaced points arranged on a curve.

The optical scanning device 10 moves one point 1 forming the input end 14a of the optical waveguide array 14 to a position corresponding to each row 23 of irregularly spaced points arranged on this distorted curve. The optical waveguide array 14 is arranged so that the optical axis of the optical beam entering each leading waveguide and the optical axis of the optical waveguide receiving the optical beam coincide at the input end 14a. to be placed.

Next, the operation of the optical scanning device 10 will be explained with reference to FIG.

The light source 11 emits a light beam that blinks at regular intervals based on an image signal, and this light beam is guided to the multiple reflection mirror 12 via a collimating lens 15 and a cylindrical lens 16. Due to the rotation of the rotary mirror 12b constituting the multiple reflection mirror 12, the light beam from the light source 11 is multiple reflected and subjected to a large deflection. This deflection causes the light source 11
The light beams from the optical waveguide array 14 are sequentially incident on each optical waveguide making up the optical waveguide array 14. Here, since each leading waveguide is arranged at non-uniform intervals on a distorted curve, even if the focus of the scanned light beam moves at non-uniform velocity and with a distortion curve motion, each waveguide is individually arranged at regular intervals. are sequentially incident on the optical waveguide. The light beams incident on the optical waveguide array 14 are propagated within each leading waveguide, and are sequentially emitted at regular intervals from output ends arranged on a straight line at regular intervals. That is,
The non-uniform and distorted motion of the light beam is converted into uniform linear motion.

By the above-described operation, the light beam from the light source 11 that blinks in response to the image signal is linearly scanned at a constant speed in the direction of the central axis of the photosensitive drum 20, and an image is recorded. Optical scanning is then performed by rotating the photosensitive drum 20 at a constant speed by a drive source (not shown) and sequentially repeating optical scanning for one line.

Note that the present invention is not limited to the embodiments described above, and changes can be made as appropriate.

For example, the output end 1 of the optical waveguide array 14 in FIG.
By arbitrarily selecting the shape and arrangement of 4b, it is possible to select not only a simple uniform linear scan but also a scanning format according to an arbitrary recording format. As an example of the scanning mode, the uniform circular scanning shown in FIG. 3 is given.

In order to realize this uniform circular scanning, the optical waveguide array 3
It is necessary to arrange the output ends 34b of the optical waveguide array 34 in a perfect circle, and to configure the vicinity of the output ends 34b of the optical waveguide array 34 in a planar manner radially from the center.

Furthermore, as shown in FIG. 4, the multiple reflecting mirror 42 can also be composed of two rotating mirrors 41a, 41b and two sets of laminated piezoelectric actuators 43a, 43b. By appropriately controlling the rotation angles of 41a and 41b, the focal locus 45 of the scanning light beam can be changed more complexly. For example, focal locus 4
5 can be made into a distorted ellipse from the reciprocating movement of the distortion curve, and in this case, since the focus of the scanned light beam does not remain stationary in space, the optical waveguide array 44
By appropriately arranging the respective optical waveguides constituting the incident end 44a of the optical waveguide, it is possible to perform optical scanning using the scanning light beam more effectively.

Furthermore, the laminated piezoelectric actuator 13a in FIG.
Instead of the drive system 13b, various drive systems such as a moving magnet system or a moving coil system galvanometer drive system may be used.

〔Effect of the invention〕

As is clear from the detailed description above, according to the present invention, the configuration is easy and It is possible to perform optical scanning according to a recording format on an optical recording medium, such as uniform velocity linear scanning or uniform velocity circular scanning, using an inexpensive optical system.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the optical scanning device of the present invention, FIG. 2 is a perspective view showing the entrance end of the optical waveguide array of the above embodiment, and FIG. 3 is an optical waveguide array of a modification of the above embodiment. FIG. 4 is a schematic perspective view of another modification, and FIG. 5 is a perspective view of a conventional optical scanning device. DESCRIPTION OF SYMBOLS 11... Light source 12a... Fixed mirror 12b... Rotating mirror 13... Drive system, 14... Optical waveguide array 20... Photosensitive drum (optical recording medium) 21... Focal locus curve. 23...Sequence of non-uniformly spaced points f! /2 Young 2 Figure

Claims (1)

[Claims] A light beam emitted from a light source is multiple-reflected between two reflective mirrors arranged opposite each other, at least one of which moves slightly, and the multiple-reflected light beam is optically scanned on an optical recording medium. In the optical scanning device, an optical waveguide array is provided between the output end of the reflecting mirror and the optical recording medium, and the input end of the optical waveguide array receives the focal locus curve of the multiple-reflected and output light beam. An optical scanning device characterized in that the light emitting end of the optical waveguide array is arranged so as to emit light in accordance with the recording format of the optical recording medium.