JP3311506B2 - Optical scanning device and optical writing device - Google Patents

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 for scanning a light beam and an optical scanning device using the optical scanning device as an optical scanning means to optically scan a surface to be scanned such as a photosensitive member of an image forming apparatus. The present invention relates to an optical writing device that performs writing.

[0002]

2. Description of the Related Art Conventionally, in an image forming section of a digital copying machine, a facsimile, a laser printer, or the like, a light beam from a light source is condensed on a surface to be scanned such as a photosensitive member via an optical scanning device and an image forming optical system. Although an optical writing device that writes an image by optical scanning while optically modulating according to an image signal is used, a rotating polygon mirror is generally used as a means for optical scanning (for example, see Japanese Patent Application Laid-Open Japanese Patent Application Laid-Open No. HEI 4-250411 discloses a method in which optical scanning is performed using a oscillating galvanometer mirror as an alternative to a rotating polygon mirror.

FIG. 6 is a view showing an example of a conventional optical writing apparatus, in which (a) is a plan view showing an optical system arrangement on a main scanning plane of the optical writing apparatus, and (b) is a plan view. FIG. 2A is a side view of the optical writing device shown in FIG.
1a is a collimator lens, 21b is a cylindrical lens having power in the sub-scanning direction, 22 is a rotating polygon mirror, 23
Denotes an imaging element formed of an fθ lens or the like, and 24 denotes a surface to be scanned such as a photoconductor. In the optical writing apparatus having the configuration shown in FIG. 1, a rotary polygon mirror 22 is used as optical scanning means, and a light beam from a light source 20 is deflected by the rotary polygon mirror 22, and is scanned via an imaging element 23. An image is formed on the surface to be scanned by forming a fine light spot thereon, and optical writing is performed. FIG. 7 is a diagram showing another example of the conventional optical writing apparatus, which uses a swinging galvanomirror 22 'as an optical scanning means.

[0004]

In a conventional optical writing apparatus, as shown in FIG. 6, a rotary polygon mirror is mainly used as an optical scanning means. The number of revolutions of the rotating polygon mirror is usually determined from the pixel density and the linear velocity, and the number of revolutions is increasing with the recent trend of higher density and higher speed. However, if the rotation speed becomes high, the bearing of the rotary polygon mirror cannot be supported by the ball bearing type, and the air bearing type must be used. For this reason, cost increases are inevitable. Also,
As the number of revolutions increases, the noise and vibration caused by the rotating polygon mirror also increase, which is a problem in environmental health. Further, as shown in FIG. 7, there has been proposed an apparatus in which an oscillating galvanomirror is used as an optical scanning unit of an optical writing device as an alternative to a rotary polygon mirror. Because it is not enough, the writing width is narrow, and it can only handle small paper sizes.
It is conceivable to increase the optical path length in order to increase the writing width. However, in this case, the size of the device is increased, and any problems remain.

The present invention has been made in view of the above circumstances, and has an optical scanning device having a novel configuration capable of performing optical scanning with a relatively simple configuration without using a rotary polygon mirror or the like, and an optical scanning device therefor. It is an object of the present invention to provide an optical writing apparatus using the optical writing means as an optical scanning means.

[0006]

In order to achieve the above object, the invention according to claim 1 comprises at least a light source which rotates or vibrates or swings, and a light source which rotates or vibrates the light source.
Alternatively, an optical scanning device that includes a swinging unit and a reflecting mirror having a curved surface that amplifies an optical scanning angle of light emitted from the light source , and performs optical scanning by a combination thereof.
The reflection mirror reflects light emitted from the light source.
Has a curved surface that focuses light at one point or almost one point, and has the curved surface
The reflecting mirror has a radius of curvature r in at least one direction.
With the reflecting surface of the reflecting mirror emitted from the light source.
So that the reflected light is concentrated at one point or almost one point
The radius of curvature r of the reflecting mirror, one point or approximately one point from the light source.
Distance La to the point, one point or approximately one point with the center of curvature of the reflecting mirror
The distance Lb between the points is set, and the center of the curvature is
On a plane passing through the line connecting the light source and the one point or approximately one point
And on a plane perpendicular to the light scanning plane by the light source
It said that there. The invention according to claim 2 is
The optical scanning device according to claim 1, wherein the reflection mirror is
Reflects light at the point or near one point where the reflected light is collected
A scanning mirror to fold the scanning light in any direction.
And features.

According to a third aspect of the present invention, there is provided an optical scanning device comprising:
An optical writing device used as an inspection means, wherein
2. The optical scanning device according to item 2, and a reflection mirror of the optical scanning device.
An image forming element for forming an image of the light on the surface to be scanned.
The one of the first and second mirrors collects light reflected by the reflection mirror.
Characterized in that it is arranged between a point or approximately one point and the surface to be scanned.
And The invention according to claim 4 is the same as the invention according to claim 3.
In the optical writing device, wherein the means for constant velocity of light to scan a surface to be scanned shall be the unit performs by changing the frequency of the light emitted from the light source.

[0008]

In the optical scanning device of the present invention and the optical writing device using the optical scanning device as the optical scanning means, the light source itself is rotated or oscillated or vibrated in place of the conventional optical scanning means such as a rotary polygon mirror. Since the optical scanning is performed by swinging, the conventional rotary polygon mirror, galvano mirror, and the like are not required, and the size and cost of the apparatus can be reduced by reducing the number of optical components. In addition, the generation of noise and vibration, which have been problems when using the rotating polygon mirror, can be eliminated because the rotating polygon mirror is not used. In addition, when the light source itself is rotated, vibrated, or swung to perform optical scanning, the light scanning angle of the light source is reduced by providing a reflecting mirror having a curved surface that amplifies the optical scanning angle of light emitted from the light source. Since it can be small, the generation of noise and vibration due to the swing of the light source can be minimized, and the speed can be increased.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a schematic configuration of a writing optical system 1a of an optical writing apparatus showing one embodiment of the present invention.
Denotes a light source unit, 5 denotes a reflecting mirror having a curved surface, 6 denotes an image forming element, 7 denotes a surface to be scanned such as a photoconductor, and 8 denotes scanning light. In the present embodiment, a light source unit 2 that rotates or vibrates or swings at least, and a curved surface that amplifies an optical scanning angle of light emitted from the light source unit 2 is used as an optical scanning unit (optical scanning device) of the optical writing device. And a reflection mirror 5 having the following configuration, and optical scanning is performed by a combination thereof.

Here, the light source unit 2 is formed in a box shape, for example, as shown in FIG. 3, and its bottom surface is supported by a light source unit support shaft 12 having an elastic deformation mode. It can rotate, swing or vibrate around the center. A light source 2b such as a semiconductor laser (LD) is provided in the box-shaped light source unit 2.
And a collimator lens 2a. An aperture (opening) 2c for narrowing and emitting light emitted from the light source 2b and collimated by the collimator lens 3a is provided on the wall surface of the light source unit 2 located on the light emission surface side of the collimator lens 2a. ing. An electrode 3b is provided on one side of the wall surface opposite to the light exit surface of the light source unit 2, and an electrode 3a is arranged outside the light source unit 2 so as to face the electrode 3b.
The power supply 14 and the switch circuit 13 are connected to the
By applying an electric charge to a in accordance with its resonance frequency, static electricity is generated between the electrodes 3a and 3b, and the Coulomb force attracts the electrodes 3a and 3b in the direction of arrow B in the drawing. Thereby, the light source unit 2 rotates in the direction of arrow A in the figure against the elastic force of the light source unit support shaft 12.
When the switch circuit 13 is turned off, the two electrodes 3a,
3b, the light source unit support shaft 1
Due to the elasticity of the light source unit 2, the light source unit 2 rotates in the direction opposite to the arrow A and returns to the original position. Therefore, by performing ON / OFF control by the switch circuit 13 in accordance with the image writing cycle, the light source unit 2 can be rocked or vibrated, and optical scanning can be performed. Although the light scanning angle of the light source unit 2 is determined by the distance between the electrodes 3a and 3b, the elasticity of the light source unit support shaft 12, and the like, the scanning angle cannot be sufficiently obtained as compared with a rotary polygon mirror or the like. For this reason, in the present invention, as shown in FIG. 1, the reflection mirror 5 having a curved surface for amplifying the optical scanning angle of the light emitted from the light source unit 2 is provided. The means for rotating, swinging or vibrating the light source (unit) 2 may be a method using an electrostatic force as shown in FIG. 3, a method using a magnetic force, a method using a vibration source such as a piezoelectric element, or the like. Various methods are applicable.

When the optical scanning means (apparatus) according to the present invention is applied to an optical writing apparatus used in a digital copying machine or the like, at least as shown in FIG.
The combination of the light source 20, the rotary polygon mirror 22, and the galvanometer mirror 22 'in 7) is replaced by the light source unit 2 and the reflecting mirror 5 having the curved surface.
In this case, the reflecting mirror 5 having a curved surface has a curvature in at least one direction so that the light emitted from the light source unit 2 is condensed at one point or substantially one point 4a, so that the optical characteristic before replacement is obtained. Can be maintained. In addition, due to the layout, as shown in FIG. 2, a mirror 4b for reflecting light is disposed at the one point or substantially one point (condensing point) 4a where the light reflected by the reflecting mirror 5 is condensed, and the scanning light 8 is formed. Can be folded back in any direction.

FIG. 4 is an explanatory view of the arrangement of the light source 2 and the reflection mirror 5 of the optical writing optical system 1a shown in FIG. 1 and the optical path, wherein (a) is an optical scanning plane (xy plane). 3) is a diagram when the positional relationship above is viewed from the z direction, and (b) is a diagram when viewed from the x direction in (a). 5A and 5B are explanatory views of the arrangement of the light source 2 and the reflection mirror 5 of the optical writing optical system 1b shown in FIG. 2 and the optical path, and FIG. 5A is a diagram on the optical scanning plane (xy plane). FIG. 7B is a diagram of the positional relationship viewed from the z direction, and FIG. 7B is a diagram of the positional relationship viewed from the x direction of FIG.

4 and 5, reference numeral 2 denotes a light source, 5 denotes a reflecting mirror having a curved surface, 5a denotes a reflecting surface of a reflecting mirror having a curved surface, 5b denotes a center of curvature of the reflecting mirror having a curved surface,
5c is a reflection point, 4a is a point or substantially one point (condensed point) at which light reflected by the reflection mirror 5 is collected, 8a is light incident on the reflection surface 5a, 8b is light reflected from the reflection surface 5a and 4a. 8c is light after passing through the light condensing point 4a, 9 is a line connecting the light source 2 and the light condensing point 4a or a plane passing through the light source 2 and the light condensing point 4a, 10a is a light scanning plane by the light source 2, Reference numeral 10b denotes a reflection plane formed by light reflected by the reflection mirror 5. R is the radius of curvature of the reflection mirror 5. FIG. 5 shows the arrangement of the reflection mirror 4b at the focal point 4a in FIG. 4. Only the direction of light after passing through the focal point 4a is different. Same as FIG. 4,
Reference numeral 10c denotes a reflection plane formed by light reflected by the reflection mirror 4b disposed at the condensing point 4a.

As shown in FIGS. 4 and 5, in the optical scanning device and the optical writing device according to the present invention, the light 8b emitted from the light source 2 and reflected by the reflection surface 5a of the reflection mirror 5 is reflected at one point or substantially one point (collection). The reflection mirror 5 is condensed on the light spot 4a.
From the light source 2 or one point (condensing point) 4 from the light source 2
a, a distance Lb between the center of curvature 5b of the reflecting mirror 5 and one point or substantially one point (condensing point) 4a is set, and the center of curvature 5 of the reflecting mirror 5 having the curved surface is set.
b is on a plane passing through a line 9 connecting the light source 2 and the one point or substantially one point (condensing point) 4a, and is disposed on a plane perpendicular to a light scanning plane 10a by the light source 2, so that left and right Even if the light scanning angle due to the swing of the light source 2 or the like is very small, the scanning angle of the light 8c reflected by the reflection mirror 5 and passing through one point or substantially one point (condensing point) 4a can be increased. be able to. Therefore, the scanning range (writing width) of the scanning light focused on the surface to be scanned 7 via the imaging element 6 can be widened, and a wide range of optical writing can be performed. Further, since the light scanning angle by the light source 2 may be small, the generation of noise and vibration due to the swing of the light source 2 can be minimized, and the speed can be increased.

Since the light source 2 swings and vibrates, the speed of light scanning on the surface 7 to be scanned such as a photoconductor becomes a problem. (The frequency of the intensity modulation according to the image signal) can be easily handled.

[0016]

As described above, in the optical scanning device of the first and second aspects, the light source itself rotates, vibrates or swings instead of the conventional optical scanning means such as a rotary polygon mirror. The scanning configuration eliminates the need for conventional rotating polygon mirrors, galvano mirrors, and the like, and can reduce the size and cost of the apparatus by reducing the number of optical components. In addition, the generation of noise and vibration, which have been problems when using the rotating polygon mirror, can be eliminated because the rotating polygon mirror is not used. In addition, when light scanning is performed by rotating, vibrating, or swinging the light source itself,
By providing a reflective mirror with a curved surface that amplifies the light scanning angle of the light emitted from the light source, the light scanning angle by the light source can be small, so that noise and vibration due to light source swing and the like are minimized. It can be suppressed, and the speed can be increased. Therefore, according to the present invention, it is possible to provide an optical scanning device capable of performing optical scanning with a relatively simple configuration, generating almost no noise or vibration, and eliminating environmental health problems.

[0017] In the optical writing device according to claim 3, by using the optical scanning apparatus according to claim 1 or 2 in place of the conventional rotating polygonal mirror or the like as an optical scanning means, according to claim 1, 2 operational effects In addition, it is possible to realize an optical writing apparatus with almost no noise or vibration by using the imaging element or the like in the conventional apparatus as it is. Further, generation of an abnormal image due to noise or vibration can be eliminated.

[0018] In the optical writing device according to claim 3,
The optical scanning device according to claim 1 or 2 is used as optical scanning means.
Thus, even if the amplitude of the light source swing or the like is small, the scanning angle after reflection by the reflecting mirror can be made large, so that a wide writing width on the surface to be scanned is possible.

In the optical writing apparatus according to the fourth aspect, the present invention provides
In addition to the effect of the third aspect, writing at a constant speed on the surface to be scanned such as a photoconductor can be easily performed.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a schematic configuration of a writing optical system of an optical writing apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating a schematic configuration of a writing optical system of an optical writing apparatus according to another embodiment of the present invention.

FIG. 3 is an explanatory diagram of a light source unit of an optical scanning device and a swinging unit thereof according to an embodiment of the present invention.

4 is an explanatory diagram of an arrangement of a light source and a reflection mirror of the optical writing optical system shown in FIG. 1 and an optical path.

5 is an explanatory diagram of an arrangement of a light source and a reflection mirror of the optical writing optical system shown in FIG. 2 and an optical path.

FIG. 6 is a diagram showing an example of a conventional optical writing device.

FIG. 7 is a diagram showing another example of a conventional optical writing device.

[Explanation of symbols]

 1a, 1b: optical writing optical system 2: light source unit 2a: collimator lens 2b: light source 2c: aperture (opening) 3a, 3b: electrode 4a: one point or substantially one point (condensing point) 4b: mirror 5: curved surface Reflecting mirror 6: Image forming element 7: Scanned surface (photosensitive member surface etc.) 8: Scanning light 12: Light source unit support shaft 13: Switch circuit 14: Power supply

Claims (4)

(57) [Claims] 1. A light source which rotates , vibrates or swings at least, and a light source which rotates, vibrates or swings the light source
Means, and a reflecting mirror having a curved surface for amplifying the optical scanning angle of light emitted from the light source , and in an optical scanning device for optical scanning by a combination thereof , the reflecting mirror is emitted from the light source Reflects light
And has a curved surface that converges light at one point or almost one point.
Reflecting mirror has a radius of curvature r in at least one direction.
Having a high efficiency and emitted from the light source to the reflecting surface of the reflecting mirror.
Therefore, the reflected light is focused on one point or almost one point.
The radius of curvature r of the reflecting mirror, one point or approximately one point from the light source.
Distance La to the point, one point or approximately one point with the center of curvature of the reflecting mirror
The distance Lb between the points is set, and the center of the curvature is
On a plane passing through the line connecting the light source and the one point or approximately one point
And on a plane perpendicular to the light scanning plane by the light source
An optical scanning device, characterized in that there. 2. The optical scanning device according to claim 1, wherein said one point or said one point where light reflected by said reflection mirror is collected.
Arranging a mirror that reflects light at approximately one point and scanning light
An optical scanning device characterized by being folded back in a direction. 3. The optical scanning device according to claim 1 or 2,
Light from the reflection mirror of the optical scanning device is imaged on the surface to be scanned.
An imaging element, which is formed by the reflection mirror.
One point or approximately one point where the reflected light
An optical writing device, which is arranged between surfaces . 4. The optical writing apparatus according to claim 3 , wherein the means for making the light scanning on the surface to be scanned at a constant speed is performed by changing the frequency of the light emitted from the light source. An optical writing device characterized by the following.