JPH0634905A - Optical scanning device - Google Patents

Abstract

PURPOSE:To reduce the size of an optical scanning device and to make the device compact with simple constitution without using a polygon mirror and a surface tilt correction optical system. CONSTITUTION:The optical scanning device consists of a prism 27 which is rotated by a scanner motor 23 and reflects the center light of incident laser luminous flux to make a deflected scan in the plane direction perpendicular to the rotary shaft 23b of a motor, a light projection unit 32 which converts the laser beam into the sort of diverged luminous flux and makes it incident on the prism 27 at an angle theta and a meniscus lens 33 which is provided in the vicinity of the prism 27 and converges the deflected light from the prism on an image formation surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device using laser light used in laser printers, laser fax machines, digital copying machines and the like.

[0002]

2. Description of the Related Art For example, in a laser printer, recording information is placed on a laser beam from a semiconductor laser, and the laser beam is deflected and scanned by an optical system to be focused on a charged photoconductor surface which is an image forming surface. The body is exposed to record the record information on the photoreceptor as an electrostatic latent image. The electrostatic latent image is then developed with toner and then transferred to a sheet at the transfer section. That is, printing is performed by the electrophotographic developing method.

In such an apparatus, the exposure of the photosensitive member is performed by a digital exposure method, and the digital exposure method is LE.
A method using a solid-state device such as D, LCD, and EEH, and a method of rotating a polygon mirror or a hologram to deflect and scan a laser beam are known. At present, the digital exposure method using a polygon mirror is the mainstream.

As a device for deflecting and scanning laser light using a polygon mirror, for example, a pre-object type using an fθ lens is known. This is Figure 4
As shown in FIG. 3, a semiconductor laser 1 is used as a light source, laser light from the semiconductor laser 1 is converted into parallel light through a collimator lens 2, and the parallel light is irradiated to a rotation-controlled polygon mirror 3 for scanning. Light, and the scanning light is f
After being reflected by the reflection mirror 5 via the θ lens 4, it is irradiated onto the photosensitive drum 7 via the cylindrical lens 6.

Also, as one not using a polygon mirror, for example, one disclosed in Japanese Patent Laid-Open No. 1-131513 is known. As shown in FIGS. 5 and 6, the deflector 11 is rotatably provided with a pyramidal mirror 12, and the pyramidal mirror 12 is provided with a cylindrical slit member 13.
Surrounded by. A circular slit 14 is provided at the bottom of the slit member 13, and a rectangular slit 15 is provided at a portion of the peripheral surface facing the reflection surface of the pyramidal mirror 12.
Then, the laser light L from the semiconductor laser unit 16 is made incident from the circular slit 14 of the deflector 11 and reflected by the reflecting surface of the pyramidal mirror 12, and the reflected light is emitted from the rectangular slit 15 as scanning light. Then, the scanning light is reflected by the reflection mirror 18 via the fθ lens 17, and is further irradiated onto the photosensitive drum 20 via the toroidal lens 19. Note that 21,2
Reference numeral 2 is an optical fiber and a photo sensor for extracting synchronous light that determines the writing position.

[0006]

By the way, the polygon mirror was considerably expensive because it was manufactured by a method of attaching an aluminum reflection film to a glass-polished product, but recently, due to the progress of ultra-precision cutting technology, a diamond cutting tool for cutting aluminum materials has been developed. It is becoming possible to drastically reduce costs by the method of drawing with. However, even if the cost can be reduced, the cutting of the polygon mirror requires a dedicated processing machine and the required accuracy is extremely high, so it accounts for more than 10% of the total cost of the optical scanning device. It was difficult to realize the decline. Further, since the polygon mirror has a plurality of reflecting surfaces, a surface tilt occurs due to a processing error of each reflecting surface. Therefore, a surface tilt correcting optical system is required, and the fθ lens 4 and the cylindrical lens 6 are used.

As described above, the former one using the polygon mirror 3 requires a dedicated processing machine for cutting the polygon mirror 3, the required accuracy becomes extremely high, and the processing error of each reflecting surface results. Since the surface tilt occurs, the fθ lens 4 and the cylindrical lens 6 must be arranged to correct the surface tilt, and moreover, the reflection mirror 5
Since the cylindrical lens 6 and the cylindrical lens 6 are arranged near the photosensitive drum 7, there is a problem that the cost becomes high and the structure becomes complicated and large.

In the latter case where the polygon mirror is not used, since there is only one reflecting surface, there is no problem of processing accuracy or surface tilt, but the fθ lens 17 and the toroidal lens 19 are arranged and the reflecting mirror is used. Since the 18 and the toroidal lens 19 are arranged in the vicinity of the photoconductor drum 20, there is a problem that the configuration becomes complicated and large as in the former case. Further, since the laser light from the semiconductor laser unit 16 is made incident from the circular slit 14 and reflected by the reflection surface of the pyramidal mirror 12, the semiconductor laser unit 16 is positioned above the deflector 11, and the height as a whole is increased. There was a problem of getting higher.

Therefore, the present invention is intended to provide an optical scanning device which can be downsized with a simple structure without using a polygon mirror or a surface tilt correction optical system and which can be reduced in height.

[0010]

The invention according to claim 1 is
A reflector that is rotated by a motor and reflects the central light of the incident laser beam to deflect and scan in a plane direction perpendicular to the rotation axis of the motor, and a laser beam that converts the laser beam into a divergent beam and forms an angle with the reflector. A laser beam emitting means for making incident at θ (however, 0 ° <θ <180 °, not including 90 °), and a converging light which is provided in the vicinity of the reflector and collects the deflected light from the reflector on the image plane. It consists of an image lens.

According to a second aspect of the present invention, a reflector rotated by a motor to reflect central light of an incident laser beam and deflect and scan the laser beam in a plane direction perpendicular to a rotation axis of the motor, and the laser beam is divergent. The laser light emitting means arranged so as to be converted into a light flux and emitted in a plane direction perpendicular to the rotation axis of the motor, and the laser light emitted from the laser light emitting means with respect to the reflector at an angle θ (however, 90 at 0 ° <θ <180 °
The prism is configured to allow the light to enter at (not including °), and an imaging lens that is provided in the vicinity of the reflector and that collects the deflected light from the reflector on the imaging surface.

[0012]

In the present invention having such a structure, the laser light converted into a divergent light beam is incident on the reflector rotated by the motor at an angle θ, and this reflector causes a plane perpendicular to the rotation axis. It is deflected and scanned in the direction. The deflected light is condensed on the image forming surface via the image forming lens.

Further, the laser light converted into a divergent light beam is refracted by the prism and is incident on a reflector rotated by a motor at an angle θ, and this reflector deflects and scans in a plane direction perpendicular to the rotation axis. To be done. The deflected light is condensed on the image forming surface via the image forming lens.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, reference numeral 21 denotes a housing having a substantially quadrangular shape and having a tubular portion 21a formed in the center thereof. The housing 21 forms a stator member of the scanner motor 23, and the tubular portion 21a of the housing 21. A bearing 22 made of a ball bearing is provided inside. The rotary shaft 2 of the rotor 23a of the scanner motor 23 is attached to the bearing 22.
3b is rotatably supported.

In the scanner motor 23, a magnet 23c is integrally attached to a rotor 23a, and the housing 2
A circuit board 25 is fixed to 1 via a spacer 24,
A coil 26 is attached to the back surface of the circuit board 25 facing the magnet 23c.

On the rotor 23a of the scanner motor 23, there are two vertical cross sections which are located on the rotary shaft 23b and are reflectors.
An equilateral triangular prism 27 is fixed.

In the prism 27, the two surfaces sandwiched by the two long sides are reflection surfaces, and the center of the surface sandwiched by the short sides is fixed to the center of the rotary shaft 23b of the scanner motor 23.

A cover member 28 is provided on the housing 21 so as to surround the scanner motor 23 and the prism 27.

An upper portion of the front surface of the cover member 28 is formed as an inclined surface which rises rearward with respect to the rotating shaft 23b of the scanner motor 23, and the semiconductor laser oscillator 29, is formed on the inclined surface.
A light emitting unit 32 in which the converging lens 30 and the slit 31 are integrally housed is detachably attached from the outside. The lower part of the front surface of the cover member 28 is formed on a wall surface parallel to the rotation shaft 23b of the scanner motor 23, and the curvature radius of the exit surface is smaller than that of the entrance surface on the wall surface, and the projection surface is convex toward the imaging surface side. A case 34 accommodating the meniscus lens 33 is attached so as to be removable from the outside. The meniscus lens 33 may be glass-polished or resin-molded.

Laser light is emitted from the light emitting unit 32 at an angle θ (where 0 ° <θ <90 °) with respect to the center of the rotary shaft 23b of the scanner motor 23 and is incident on the reflecting surface of the prism 27. It is supposed to be done. The prism 27 is configured to deflect and scan the laser light incident by the rotation of the rotor 23a in a plane direction perpendicular to the axial direction of the rotary shaft 23b of the scanner motor 23.

The meniscus lens 33 is adapted to form an image of the deflected light reflected by the reflecting surface of the prism 27 on the photosensitive surface of a photosensitive drum (not shown).

In the embodiment having such a structure, the laser light from the semiconductor laser oscillator 29 is converted into a diverging light flux by the converging lens 30, and then shaped into a circular beam by the slit 31, and the rotor is rotated at an angle θ. The light is incident on the reflecting surface of the prism 27 arranged on 23a. The laser light incident by the rotation of the prism 27 is converted into deflected light which is deflected and scanned by a predetermined width in a plane direction perpendicular to the rotation axis 23b of the scanner motor 23, passes through the meniscus lens 33, and forms an image. It is imaged on the surface. The meniscus lens 33 narrows the laser beam and corrects the main and sub field curvatures. The f-θ correction is performed electrically.

Since the deflected light is obtained by the prism 27 as described above, it is not necessary to use a polygon mirror or a surface tilt correction optical system, so that the structure can be simplified and the economical efficiency can be improved. Further, the prism 27 is fixed on the rotor 23a of the scanner motor 23, and the case 34 accommodating the light emitting unit 32 and the meniscus lens 33 is attached to the cover member 28 at a predetermined position. Since this is not used, the configuration can be simplified and the size can be reduced in this respect as well.

Further, since the case 34 is attached to the lower portion of the front surface of the cover member 28 and the light emitting unit 32 is attached to the upper portion of the front surface in an inclined manner, the height can be reduced as a whole, and the size can be reduced. be able to.

Next, another embodiment of the present invention will be described with reference to the drawings. The same parts as those in the above embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The cover member 35 shown in FIG. 2 has a wall surface parallel to the rotary shaft 23b of the scanner motor 23 used as the cover member, and the front wall surface of the cover member 35 is used. A case 34 accommodating a meniscus lens 33 integrally housed by resin molding is attached to the lower part of the above, and a light emitting unit 32 is attached to the upper part of the case 32.
Attach it so that it is parallel to the laser light emitted from
The front surface of the light emitting unit 32, that is, the slit 31.
On the outer surface side of the light emitting unit 3 such that the angle of incidence on the reflecting surface of the prism 27 becomes an angle θ (where 0 ° <θ <90 °) with respect to the center of the rotating shaft 23b of the scanner motor 23.
A prism 36 for refracting the laser light from 2 is attached.

Even in such a structure, the structure can be simplified, miniaturized, and made compact as in the above embodiment.

In FIG. 3, a scanner motor 23 'having a rotary shaft 23b' penetrating the rotor 23a 'and protruding upward is used as the scanner motor.
The prism 37 is mounted upside down on the tip of b ', and the upper and lower front parts serve as cover members for the scanner motor 2
A cover member 38 having a wall surface parallel to the rotating shaft 23b 'of 3'is used, and a case 34 in which a meniscus lens 33 is integrally housed by resin molding is attached to the upper part of the front wall surface of the cover member 38. At the same time, a light emitting unit 32 is attached to the lower part so that the laser light from the unit 32 becomes parallel to the laser light emitted from the meniscus lens 33, and the front surface of the light emitting unit 32,
That is, on the outer surface side of the slit 31, the light emitting unit 32 is arranged so that the angle of incidence on the reflecting surface of the prism 37 is an angle θ (where 90 ° <θ <180 °) with respect to the center of the rotation axis of the scanner motor 23 ′. A prism 39 for refracting the laser light from is attached.

Even in such a structure, the structure can be simplified, miniaturized, and made compact as in the above-described embodiment.

In the above embodiment, a prism having an isosceles triangular cross section as a reflector is used, and two long side portions of the prism are used as reflecting surfaces. However, the present invention is not limited to this. A rectangular prism may be used, and one long side of the rectangular prism may be used as a reflecting surface.
In this case, there is only one reflecting surface. In addition to the prism, a mirror may be used as the reflector.

Further, since the structure is such that the two-faced reflector is used to perform one rotation and two scans, the face tilt basically occurs. Therefore, the tilt of the surface is kept small by adjusting the mounting angle of the reflector. If there are three or more surfaces, the surface tilt cannot be suppressed unless the reflecting surfaces can be adjusted for each surface, so an optical correction system is indispensable.

[0033]

As described above, according to the present invention, downsizing can be achieved with a simple structure without using a polygon mirror or a surface tilt correction optical system, and the height can be reduced to achieve compactness. It is possible.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing another embodiment of the present invention.

FIG. 3 is a sectional view showing another embodiment of the present invention.

FIG. 4 is a perspective view showing a conventional example.

FIG. 5 is a configuration diagram showing another conventional example.

FIG. 6 is a diagram showing a configuration of a deflector of the conventional example.

[Explanation of symbols]

 23 ... Scanner motor 27 ... Isosceles triangular prism 29 ... Semiconductor laser oscillator 32 ... Light emitting unit 33 ... Meniscus lens

Claims (2)

[Claims] 1. A reflector which is rotated by a motor and reflects center light of an incident laser beam to deflect and scan in a plane direction perpendicular to a rotation axis of the motor, and converts the laser beam into a divergent beam. The angle θ with respect to the reflector (where 0 ° <θ
<180 ° and not including 90 °) and a laser beam emitting means, and an imaging lens provided in the vicinity of the reflector and converging the deflected light from the reflector on the image plane. Optical scanning device. 2. A reflector which is rotated by a motor and reflects center light of an incident laser beam to deflect and scan in a plane direction perpendicular to a rotation axis of the motor; and a laser beam converted into a divergent beam. A laser beam emitting means arranged to emit in a plane direction perpendicular to the rotation axis of the motor, and a laser beam emitted from the laser beam emitting means with respect to the reflector at an angle θ (where 0 ° < a prism for making incident light at θ <180 ° (not including 90 °), and an imaging lens provided in the vicinity of the reflector and condensing the deflected light from the reflector on an image plane. Optical scanning device.