JP2978688B2 - Optical device and image forming apparatus - 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 device suitable for a laser beam printer or the like for guiding a light beam to a scanning object via a lens group and a light deflecting device.

[0002]

2. Description of the Related Art Generally, in an optical device incorporated in an image forming apparatus such as a laser beam printer, a light beam generated from a light source, that is, a semiconductor laser (hereinafter, referred to as a laser) is
It is arranged between the laser and the optical deflector, and is converted into parallel light via a pre-deflection optical system for converting the beam shape of the light beam generated from the laser.

The light beam converted into parallel light by the pre-deflection optical system is deflected in a desired direction by a light deflector having a plurality of rotatable reflection surfaces. This deflected light beam is shaped into a desired shape through a post-deflection optical system including a lens group for shaping the shape of the light beam into the most ideal shape when used in a printer device. At the same time, an image is formed on a scanning object, that is, a desired position on the photosensitive member.

The pre-deflection optical system includes a combination of a glass lens for collimating a light beam generated from a laser, a plurality of plastic lenses for giving the light beam a converging property, and the like.

The light deflecting device has a plurality of deflecting / reflecting surfaces (polyhedral mirrors) rotatably formed via a motor or the like. The reflecting surface, when rotated, deflects the light beam from the laser toward the photoconductor with its rotation.

The post-deflection optical system includes an fθ lens that makes the reflection angle θ of the light beam deflected via the light deflector and the position of the light beam imaged on the photosensitive member in the main scanning direction proportional. I have.

Since the fθ lens has a small curvature in the sub-scanning direction, the light reflected inside the lens itself may return to the emission surface and be emitted to the image forming area.

For this reason, Japanese Patent Application Laid-Open No. 5-19195 discloses that a light beam passing through an fθ lens is passed with the optical axis of the lens deviated, the curvature in the sub-scanning direction is increased, and the position of the lens is increased. A method has been proposed in which the internally reflected light is separated from the principal ray and the vicinity of the lens by deviating from the plane connecting the light deflecting device and the scan target.

[0009]

However, in the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 5-19195,
There is a problem that the size (thickness) of the optical device in the sub-scanning direction is increased because a space is required to completely separate the internally reflected light.

Also, in the sub-scanning direction, even if a method of blocking the internal reflected light by blocking an area other than the area through which the principal ray is transmitted, if the internally reflected light is not separated from the principal ray in the vicinity of the lens. Therefore, there is a problem that the size of the optical device is increased. An object of the present invention is to provide an optical device that is less susceptible to internal reflected light that degrades an image.

[0011]

According to a first aspect of the present invention, there is provided an optical apparatus for converting a light beam from a light source into a parallel light or a convergent light, and applying the light beam passed through the optical unit to an object to be scanned. An optical deflecting device for deflecting light toward
An image forming lens for forming an image of the light beam reflected by the light deflector on the surface of the object to be scanned, and a flange provided at an end for reinforcing the image forming lens; The angle formed by the principal ray of the light beam at the swing angle of 0 ° with the part is the exit angle of the principal ray of the light beam from the exit surface of the lens out of the image area of the lens, and the light beam is Each of the angles of emergence of the internally reflected light, which is reflected on the exit surface and further returned to the exit surface while being reflected on the entrance surface of the lens and exits to the outside of the image area of the lens. It is characterized in that it is formed relatively large.

According to a second aspect of the present invention, there is provided an optical unit for converting a light beam from a light source into a parallel light or a converged light, and an optical deflection unit for deflecting the light beam passed through the optical unit toward an object to be scanned. Device, an image forming lens for forming an image of the light beam reflected by the light deflector on the surface of the object to be scanned, and a flange provided at an end for reinforcing the image forming lens. , The end of the imaging lens
The bent portion to provide a flange portion, sub-scanning read as the light beam passing through the ends, does not touch the object to be scanned
A predetermined angle is given to the inspection direction . An image forming apparatus according to claim 3, wherein an optical unit that forms an electrostatic latent image by guiding a light beam onto the photoconductor, and a developing device that develops the electrostatic latent image formed by the optical unit. Having the optical unit, an optical unit that converts a light beam from a light source into parallel light or converged light, and an optical deflector that deflects the light beam that has passed through the optical unit toward an object to be scanned. An image forming lens for forming an image of the light beam reflected by the light deflector on the surface of the object to be scanned, and a flange provided at an end for reinforcing the image forming lens; The angle between the part and the principal ray of the light beam at a swing angle of 0 ° is the image of the principal ray of the light beam from the exit surface of the lens.
Emission angle and the light beam to a region outside is reflected by the exit surface of the lens, yet on the internal reflected light is emitted back into the emitting surface again while being reflected by the incident surface of the lens
It is characterized in that it is formed to be larger than each of the exit angles of the lens out of the image area . An image forming apparatus according to claim 4, wherein an optical unit for forming an electrostatic latent image by guiding a light beam onto the photosensitive member, and a developing device for developing the electrostatic latent image formed by the optical unit. Having the optical unit, an optical unit that converts a light beam from a light source into parallel light or converged light, and an optical deflector that deflects the light beam that has passed through the optical unit toward an object to be scanned. An image forming lens for forming an image of the light beam reflected by the light deflector on the surface of the object to be scanned, and a flange provided at an end for reinforcing the image forming lens; Folds to provide a flange at the end of the image lens
To bend the light beams passing through the ends, characterized in that the predetermined angle in the sub-scanning direction so as not to touch the object to be scanned is given.

[0013]

According to the present invention, since the imaging optical system has the flange portion formed so that the reflected light beam is guided to a predetermined range, the light beam deflected via the light deflecting device is used for image formation. it no optical device is incident on the region obtained <br/> is Ru.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 7 show a schematic configuration of a main part of a scanning optical device used in a laser beam printer or the like.

The optical device 2 includes a light emitting unit 10 integrally including a semiconductor laser element for generating a laser beam, and a lens group for shaping the cross-sectional shape of the laser beam from the laser element into a desired shape. A light deflecting device 20 for deflecting the deflected laser beam toward a photoreceptor 50, which will be described later, and a lens that forms the laser beam deflected via the light deflector 20 onto a recording surface of the photoreceptor substantially linearly. It includes an imaging optical system 30 having a group, and a housing 40 that hermetically houses the light emitting unit 10, the light deflector 20, and the imaging optical system 30.

The light emitting unit 10 includes a semiconductor laser element 12,
A first lens 14 given a predetermined convergence, a second lens 16 given a positive power in the sub-scanning direction, and a first lens 14
And a stop 18 arranged between the second lenses 14 and 16 for shaping the laser beam into a desired shape. The first lens 14 and the second lens 16 are each made of optical glass, for example, BK7.

The semiconductor laser element 12 is controlled by a laser holder 68, a first lens 14, a second lens 16,
Are fixed to the housing 40 by a lens barrel (or lens holder) 66 made of, for example, aluminum die-cast or plastic such as PPS. In this case, the semiconductor laser element 12 may be disposed integrally with the lens barrel and the lens holder 66. Further, the laser holder 68 and the lens holder 66 may be fastened. Note that a member for positioning with the housing 40 (not shown) is formed in the lens barrel (lens holder) so as to be accurately fixed to the housing 40, and is fixed with screws. In addition, the cylindrical lens (second lens) 16
The housing 40 is provided by the cylindrical lens holder 64.
Although the light emitting unit 10 is fixed independently of the light emitting unit 10, it may be integrated with the light emitting unit 10.

The light beam emitted from the semiconductor laser element 12 of the light emitting unit 10 is converted into a first lens (condensing lens) 14.
The light is converted into a convergent light or a parallel light, and is limited to a predetermined beam spot by the diaphragm 18.

The beam shaped into a desired beam spot by the stop 18 is guided to the optical deflector 20 through the cylindrical lens 16 having a positive power in the sub-scanning direction. The light deflector 20 is provided with a deflecting mirror 22 which is a rotating polygon mirror having eight plane mirrors, and an axial gap type scanner motor 24 for rotating the deflecting mirror 22.

The scanner motor 24 has a motor shaft 24a rotatably supported via bearings (not shown, see FIG. 2 ) and a rotor 24b integrally formed with the shaft 24a. A deflecting mirror 22 is fixed to the bearing surface of the rotor 24b with a retaining ring and a spring material or a screw, and is rotated in a predetermined direction with the rotation of the motor.

As the scanner motor 24, besides the axial gap type, a radial type scanner motor using a dynamic pressure bearing, a motor using a magnetic fluid, or a motor using a direct bearing can be used.

The laser beam reflected by the deflecting mirror 22 of the light deflecting device 20 is deflected toward the reflecting mirror 60 and totally reflected via the reflecting mirror 60, and then the third and fourth scanning lenses 32 And 34 to the imaging optical system 30.

The laser beam guided to the imaging optical system 30 is
The third and fourth scanning lenses 32 and 34 cause the light deflecting device 20 to operate.
A predetermined convergence is given according to the rotation angle of the reflection surface 22 of
An image is formed at a predetermined position on the photoreceptor 50 in order with a substantially equal beam diameter.

Next, the position and length of the reflection mirror 60 will be considered. The reflecting mirror 60 is in a plane including the optical axis. At this time, if the number of surfaces of the rotating polygon mirror is N and the radius of the inscribed circle is r, the laser beam reflected by the reflecting surface and the rotation center of the rotating polygon mirror are aligned. They are arranged so as to be separated by r / cos (π / N) or more.

Next, the reflection mirror 60 is formed by the imaging optical system 30.
A method for correcting distortion and curvature of field when forming a laser beam reflected on the photosensitive member 50 into an image will be described.

The third lens 32 and the fourth lens 34 are each made of a plastic material such as PMMA (polymethyl methacryl). The optical axis O ₁ from the light emitting unit 10 to the light deflector 20 (see FIG. 1)
The optical axis O ₂ (see FIG. 1 ) of the laser beam traveling from the optical deflector 20 to the third lens 32 is disposed on the same plane.

[0027]

In the main scanning direction, the third and fourth lenses 32 and 34 have an image height h on the photosensitive member 50 with respect to the rotation angle θ of each reflecting surface of the deflecting reflecting mirror 22, and a focal point of the imaging optical system 30. When the distance is f, the curvature of each lens is defined so as to satisfy h = fθ.

The third and fourth lenses 32 and 34 are
In the main scanning direction in a state of being combined with each other, the influence of the curvature of field of the laser beam of the reflected light reflected from the reflecting surface of the deflecting mirror 22 is reduced, and the distortion is set to an appropriate value. The laser beam is formed so that the surface tilt correction surfaces on all surfaces of the photoreceptor 50 coincide with each other. In addition, between the fourth lens 34 and the photoreceptor 50, a folding mirror 3 that bends the optical path of the laser beam.
6, and a dustproof glass 38 that allows the laser beam to reach the photoconductor 50 while sealing the housing 40 is arranged.

The housing 40 defines a position where the light emitting unit 10 (here, a lens barrel will be described as an example) should be disposed (not shown). A deflecting device positioning mechanism (not shown) and a plurality of mirrors for accurately fixing the reflecting mirror 60, the third lens 32, the fourth lens 34, the folding mirror 36, and the dust-proof glass 38 forming the imaging optical system 30. The fixing guide members 42a and 42b, 44a and 44b, and the reflection mirror fixing guide member 62 are integrally formed in advance. In this apparatus, the folding mirror 36 and the dustproof glass 38 are fixed to the same fixing guide members 46a and 46b.

The third lens 32 is connected to the fixing guide members 42a and 42b, and the fourth lens 34 is connected to the fixing guide members 44a and 42b.
44b, the folding mirror 36 and the dust-proof glass 38 are fixed to the fixing guide members 46a and 46b, and further, the reflecting mirror 60 is
The fixing guide members 62 are adhered and fixed by a visible light curable resin adhesive that is cured by irradiating the fixing guide members 62 with visible light.

The housing 40 has a reflection mirror
60, a third lens 32, a fourth lens 34, a folding mirror 36, and a dust-proof glass 38, and a horizontal synchronization detecting mirror for detecting horizontal synchronization of the laser beam in the main scanning direction.
52a and a synchronization signal detector 52b are provided.

The mirror 52a for horizontal synchronization detection is a laser beam that has passed through the fourth lens 34 in the main scanning direction, and is located in a region of the laser beam that becomes an image to be printed when it reaches the photoreceptor 50. Also in the outer area, the detector 52b
Are located at positions where the laser beam reflected via the mirror 52a can be reliably detected.

In this case, it is necessary to emit a laser beam within a predetermined range outside the image area of the lens in order to detect the horizontal synchronization signal. However, the fourth lens 34
(Or third lens 32), the flange portion 34a (or 32a) is Ru are formed together to increase strength and self-supporting.

According to FIG. 4, the flange portions 34a (32a) of the fourth lens 34 (or the third lens 32) respectively
First surface of lens 34 (32) (light deflecting device 22 side, that is, incident surface)
The center of the lens so that it does not reflect the laser beam that has passed through the second surface (the photoreceptor 50 side, ie, the exit surface).
The laser beam is formed at a predetermined angle in a direction equal to the direction in which the laser beam is deflected with respect to (a swing angle of 0 °).

In this case, the angle β between the flange portion 34a (32a) and the laser beam at the swing angle of 0 ° is determined by the emission angle θ ₁ of the laser beam from the emission surface of the fourth lens 34 (third lens 32), And the laser beam is reflected at the exit surface,
Further, the laser beam is formed so as to be larger than the emission angle θ ₂ of the internally reflected laser beam which is returned to the emission surface again while being reflected on the incident surface.

Referring to FIG. 5, the bent portion (leg) 34b (32b) which is the end of the fourth lens 34 (or the third lens 32) and provides the flange portion 34a (32a) is provided in the sub-scanning direction. The direction is given a predetermined angle α (≠ 0) .

As is apparent from FIG. 5, the lens 34 (32)
Part of the laser beam is converted to a lens by the second surface (emission surface)
34 Even when the laser beam is returned to the first surface (incident surface) of (32), the laser beam due to internal reflection is largely separated from the direction in which the principal ray is emitted at an angle α,
It is possible to prevent the internally reflected laser beam from being exposed in the 50 image areas. That is, such a predetermined angle α is set.
The laser that has passed through the end of the lens 34 (32).
Make sure that the beam does not hit the scanning object in the sub-scanning direction.
can do.

Incidentally, the internally reflected laser beam generated on the light emitting unit 10 side of the light deflector 20, that is, the second lens
When the internally reflected laser beam from 16 is incident on the cylindrical rotating body, that is, the pedestal of the polygon mirror 22 or the motor unit 24,
The reflected light is reflected to a fixed position. The reflected light exposes a fixed point during one main scan, even if the amount of energy is weak.

Referring to FIG. 6, in the light deflecting device 20 of the optical device 2 of the present invention, the cylindrical portion (the polygon mirror 22) of the light deflecting device 20 is used.
In order to prevent the laser beam from being directly incident on the pedestal portion or the motor portion 24), the light deflector 20 is covered with a light-shielding member 26 except for the direction in which the principal ray of the laser beam is incident.

FIG. 7 shows a pedestal portion and a shaft portion or a motor portion 24 of the polygon mirror 22 in place of the light shielding member 26 shown in FIG.
In this case, an example is shown in which the outer shape is formed in a conical shape. According to FIG. 7, substantially the same effect as in the case where the light shielding member 26 shown in FIG. 6 is used can be obtained.

FIG. 8 shows an example of a laser beam printer as an image forming apparatus in which the optical device shown in FIGS. 1 to 7 is incorporated. The image forming apparatus or the laser beam printer 100 includes a photoconductor as a cylindrical image carrier rotatable along an arrow.
50, a process unit 110 for forming an image based on image data supplied from an external device, and a material to be transferred, that is, paper P, is fed toward the process unit 110, and is formed via the process unit 110. Printer device that outputs the printed image as print output (hard copy) 1
02.

The process unit 110 is detachably formed in the printer 102 which outputs an image formed through the unit 110. A sheet P on which an image formed via the photoconductor 50 is transferred to the printer device 102.
The first and second cassettes (which will be described later) are formed so as to be detachable.

Around the photosensitive member 50 in the process unit 110, a charging device 12 for charging the photosensitive member 50 with a predetermined charge is provided.
0, a developing region 122a is formed between the photosensitive member 50 and the photosensitive member 50, and the electrostatic latent image formed on the photosensitive member 50 is developed by supplying a hot-melt toner to the electrostatic latent image. The developing device 122 is opposed to the photoreceptor 50 to form a transfer area 124a between the photoreceptor 50 and the unit 110, and is formed on the photoreceptor 50 on a sheet P fed from a sheet cassette described later. Transfer device 124 for transferring the transferred toner image, photoconductor 50
Cleaning device that scrapes off residual toner remaining in the printer 12
6, and a pre-exposure device 128 for stabilizing the amount of electric charge charged to the photoconductor 50 are sequentially arranged along the rotation direction of the photoconductor 50.

The photoreceptor 50 is rotated at a rotation speed corresponding to a recording density, which will be described later, that is, the number of laser beams emitted from the laser exposure device 2 per inch through a motor (not shown).

The charging device 120 employs a scorotron having a grid screen disposed between the corona wire and the photoreceptor and capable of limiting the amount of electric charge toward the photoreceptor 50.
The developing device 122 includes a developer in which a toner (not shown) and a carrier (not shown) are mixed, and a magnet roller 122b that conveys the developer toward the photoconductor 50.
The image data to be output is developed by selectively supplying toner to the electrostatic latent image formed in the printer. Developing device
A toner cartridge (not shown) can be attached to and detached from 122, and toner consumed by developing the electrostatic latent image is replenished in accordance with the consumed amount.

As the transfer device 124, a corotron that can reliably draw the toner image on the surface of the photoconductor 50 onto the paper P is used. The cleaning device 126 includes an elastic blade 126a that contacts the photoconductor 50 and a toner collecting case 126b.
And is developed through the developing device 122, and is transferred to the transfer device 124.
The remaining toner image (residual toner) transferred to the paper P is scraped off from the photoreceptor 50 and collected.

Between the charging device 120 and the developing device 122 of the process unit 110, a laser beam from the exposure device (optical device) 2 described in detail with reference to FIGS. Exposure window 114 is formed.

The laser exposure apparatus 2 is, for example, 600 [d
[pi], ie, 600 [dots per inch], and a laser beam generated from the semiconductor laser 12 is passed through the first and second lenses 14 and 16 to a predetermined beam spot, A beam spot corresponding to 600 [dpi] is given, and is sequentially deflected in the axial direction of the photoreceptor 50 by the deflecting device 20, that is, the rotating polygon mirror 22.
The laser beam deflected via the rotary polygon mirror 22
The fourth lens 32 and the fourth lens 32 provide convergence so that the same beam spot is formed at any position on the photoconductor 50, is reflected by the folding mirror 38, and is irradiated on the photoconductor 50 through the exposure window 114. You. Needless to say, the rotation speed of the rotary polygon mirror 22 corresponds to 600 lines / inch.

Cassette 1 to be attached to printer device 102
Between the process units 110 and 32a and 132b, one sheet of paper P is pulled out from one of the cassettes.
First and second take-out rollers 134a and 134b for feeding (the drawn-out paper P) to the transfer area 124a, first and second paper take-out guides 136a and 136b, first and second transport rollers The pair 138a and 138b, the first and second paper conveyance guides 140a and 140b, and the inclination during conveyance that may occur in the paper P fed from the respective cassettes are removed, and the photoconductor 50 of the process unit 110 is removed.
An aligning roller pair 150 for aligning the position of the image formed on the sheet P with the position of the sheet P.
And a transfer guide roller 154 for ensuring that the sheet P is in close contact with the photoreceptor 50, and the like.

In the vicinity of the cassettes 132a and 132b, a paper detection switch (not shown) for detecting the presence or absence of the paper P stored in each cassette, the size of the paper P stored in each cassette (actually,
A paper size detection switch (not shown) for detecting the identification code displayed on the cassette (not shown) and a cassette detection switch (not shown) for detecting that each cassette is mounted on the printer 102 are provided. ing.

On the side of the second paper transport guide 140b,
Independently of the cassettes 132a and 132b, a manual paper feed guide 156 capable of feeding paper P of various sizes is incorporated. Printer 102 via Manual Feed Guide 156
The paper P inserted inside the second paper transport guide 140
b and is used in the same manner as the sheet P fed from the cassettes 132a and 132b.

The side of the process unit 110 opposite to the transfer guide roller 154 across the transfer area 124a, that is, the direction in which the paper P on which the toner image has been transferred is passed through the transfer area 124a. The paper guide 158 transports the paper P on which the toner image has been transferred, and the paper P by heating and pressing the toner of the toner image transferred onto the paper P.
A fixing device 160 for fixing the toner image is provided.

The fixing device 160 includes a heating roller 162 in which a heating heater 164 is provided, a pressure roller 166 extending along the axis of the roller 162, and disposed so as to be in pressure contact with the roller 162, and a roller 162. And 166 containing a housing 160a.

The housing 160a is formed so as not to release the heat from the heater 164 in order to secure a temperature at which good fixing is possible. The heating roller 162 is a hollow cylinder formed of a metal having good heat conductivity, for example, aluminum, and has a surface (not shown) coated to prevent adhesion of molten toner. I have. The pressure roller 166 has an elastic layer, for example, a rubber layer formed on the surface. On the outer peripheral surface of the heating roller 162, dirt on the roller surface, that is, attached toner or paper P
162 for removing fine powder and dust from the soil
a is pressed along the axis. A thermistor 162b for detecting the temperature of the outer peripheral surface of the roller 162 is located on the outer peripheral surface of the heating roller 162, and the heater 164 is controlled based on the temperature of the outer peripheral surface of the roller 162 detected via the thermistor 162b. Thus, the outer peripheral surface of the roller 162 is maintained at an optimum temperature.

In the direction in which the paper P on which the toner image has been fixed via the fixing device 160 is sent out, that is, downstream of the fixing device 160, a first pair of discharge rollers 170 for discharging the paper P to the outside of the printer device 102 are provided. A reversing path for turning the sheet P sent from the first discharge roller pair 170 over,
Switching gate 172 leading to 174 and switching gate 172
And a second discharge roller pair 176 that discharges the inverted sheet P to the outside of the printer device 102 via the inversion path 174. The first stock tray 178 is also diverged via the switching gate 172 to a position where the sheet P which is urged through the first discharging roller pair 170 and passed through the switching gate 172 is discharged, A second stock tray 180 (part of the outer cover of the printer main body) is disposed at a position where the sheet P sent through the reversing path 174 and the second discharge roller pair 176 is discharged. I have.

Next, the operation of the printer body 100 of the present invention will be described. When a main switch (not shown) is turned on, the printer body 100 is initialized (initialized) according to a program stored in a ROM (not shown).
Is done.

Image data supplied from an external device such as a word processor or a host computer via an interface (not shown) is sequentially stored in a RAM (not shown) (and an extension RAM (not shown) according to the amount of data), and is stored in a CPU (not shown). After being developed into bitmap data by control, the data is sequentially output to the exposure device (optical device) 2.

On the other hand, in accordance with the input data or a control signal input from the operation panel, a paper cassette containing paper P suitable for printing data to be output is selected, and a toner cassette to be described later is selected. Waiting for image transfer.

In parallel with this, the photosensitive member 50 is rotated at a desired rotation speed via a motor (not shown), and the charging device 120 is rotated.
A desired electric potential is given through. At the same time, the selected paper P is taken out via the corresponding take-out roller and paper guide, and is conveyed to the aligning roller pair 150.

At the same time, the image data converted to serial data via a signal conversion circuit (not shown) is supplied to the exposure device 2 in accordance with the vertical synchronization signal from the vertical synchronization detection device 52b, and is generated from the laser element 12. The intensity of the laser beam is continuously changed according to the data. The laser beam whose intensity is continuously changed according to the image data is successively transmitted to the photoconductor 50 and converted into an electrostatic latent image. The image converted to a latent image on the photoconductor 50 is guided to a development area facing the developing device 122 with the movement of the photoconductor 50, and toner is selectively supplied to the latent image via the developing device 122. The transfer is performed along with the rotation of the photoconductor 50 and is transferred to a transfer area facing the transfer device 124.

On the other hand, the toner image on the photoreceptor 50 and the paper P are
The charge remaining on the photoconductor 50 is adsorbed (closely adhered) to the photoconductor 50. Thereafter, under the control of the CPU, a charge having the same polarity as the charge already applied to the photoconductor 50 (for forming a latent image) is supplied from the transfer device 124 to the photoconductor 50 on the photoconductor 50 and the paper P. Then, the toner image on the photoconductor 50 is transferred to the paper P.

The paper P on which the toner image is placed is transferred to the fixing device 160
The toner, which is heat-fusible, is melted through the fixing device 160, and the toner image is fixed (fixed) to the paper P. On the other hand, the photoconductor 50 on which the paper P and the toner image are separated
Is further rotated, returned to the initial state by the cleaning device 126, and used for the next image formation. Paper P on which a toner image has been formed by a series of image forming processes
Is the stock tray 178 to be discharged through the gate 172
Or 180, stocked in order.

[0064]

As described above, according to the optical apparatus of the present invention, the scanning lens located near the photoreceptor has:
The light beam deflected via the light deflector enters the image forming area because it has a flange portion formed so that an undesired reflected light beam due to internal reflection of the scanning lens is guided to a predetermined range. Optical device without
You. What slave, little image deterioration optical apparatus and an image forming apparatus is provided.

[Brief description of the drawings]

FIG. 1 is a plan view of an optical device according to an embodiment of the present invention.

2 is a sectional view of the optical deflector of the optical device shown in FIG. 1 at a swing angle of 0 °.

FIG. 3 is an optical path diagram of the optical device shown in FIG. 1 as viewed from above.

FIG. 4 is a partially enlarged view showing an end of a scanning lens of the optical device shown in FIG. 1;

5 is a cross-sectional view of the end of the lens shown in FIG. 4 taken along line 5-5.

FIG. 6 is a schematic diagram showing an example of light blocking of a light deflecting device of the optical device shown in FIG. 1;

FIG. 7 is a schematic diagram showing a modification of the light-shielding example of the optical deflector of the optical device shown in FIG. 7;

FIG. 8 is a schematic cross-sectional view showing an example of a laser beam printer in which the optical device shown in FIGS. 1 to 7 is incorporated.

[Explanation of symbols]

2 optical device, 10 light emitting unit, 12 semiconductor laser element, 14 first lens, 16 second lens, 18 stop, 20
Optical deflecting device, 22… deflection mirror, 24… Scanner motor, 26
... Shielding member, 30. Imaging optical system, 32. Third lens, 34. Fourth lens, 34a. Furan 36. Folding mirror, 38. Dustproof glass, 40. Housing, 42a, 42b. Member, 44a, 44b: fourth lens fixing guide member, 46a, 46b: folding mirror and dustproof glass fixing guide member, 50: photoconductor, 52a: horizontal synchronization detection mirror, 52b: synchronization signal detector, 60 ... Reflective mirror, 62: Guide member for fixing the reflective mirror, 64: Cylindrical lens holder, 66: Lens barrel, 68: Laser holder, 102: Printer device, 110: Process unit, 120: Charging device, 122:
Developing device, 124… Transfer device, 126… Cleaning device,
128: pre-exposure device, 132a, 132b: cassette, 134
a, 134b: take-out roller, 136a, 136b: paper take-out guide, 138a, 138b: transport roller pair, 140a, 1
40b: Paper transport guide, 150: Aligning roller pair,
152: paper guide before transfer, 154: transfer guide roller, 1
56: manual feed guide, 160: fixing device, 162: heating roller, 164: heating heater, 166: pressure roller, 170: discharge roller pair, 172: switching gate, 174: reversing passage, 176
… Second discharge roller pair, 178… first stock tray,
180 ... Second stock tray.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02B 26/10 B41J 2/44

Claims (4)

(57) [Claims] 1. An optical unit for converting a light beam from a light source into parallel light or convergent light, an optical deflecting device for deflecting a light beam passed through the optical unit toward an object to be scanned, and the optical deflecting device. An image forming lens for forming an image of the light beam reflected on the surface of the object to be scanned, and a flange provided at an end for reinforcing the image forming lens; The angle formed by the principal ray of the light beam at 0 ° is the exit angle of the principal ray of the light beam from the exit surface of the lens to the outside of the image area of the lens, and the light beam is reflected by the exit surface of the lens. Is further returned to the exit surface while being reflected by the entrance surface of the lens, and the internally reflected light emitted out of the image area of the lens.
The optical device is formed to be larger than each of the exit angles. 2. An optical unit for converting a light beam from a light source into a parallel light or a convergent light, an optical deflecting device for deflecting the light beam passed through the optical unit toward an object to be scanned, and the optical deflecting device. An imaging lens that forms an image of the light beam reflected on the surface of the object to be scanned, and a flange portion provided at an end for reinforcing the imaging lens; Bend that provides the flange portion of the
The Ri portion, the light beams passing through the ends, the optical apparatus characterized by a predetermined angle in the sub-scanning direction so as not to touch the object to be scanned is given. 3. An optical system for forming an electrostatic latent image by guiding a light beam onto a photoreceptor, and a developing device for developing the electrostatic latent image formed by the optical unit, The optical means includes: an optical unit that converts a light beam from a light source into parallel light or converged light; an optical deflecting device that deflects the light beam that has passed through the optical unit toward an object to be scanned; An image forming lens for forming an image of the reflected light beam on the surface of the object to be scanned, and a flange provided at an end for reinforcing the image forming lens; The angle between the principal ray of the light beam in ° and the exit angle of the principal ray of the light beam from the exit surface of the lens to the outside of the image area of the lens and the light beam is reflected by the exit surface of the lens. ,
Further, an image of the lens of the internally reflected light that has been returned to the emission surface again while being reflected by the incident surface of the lens and emitted.
An image forming apparatus characterized in that the image forming apparatus is formed to be larger than each of the outgoing angles to the outside of the region . 4. An optical system for forming an electrostatic latent image by guiding a light beam onto a photoreceptor, and a developing device for developing the electrostatic latent image formed by the optical unit, The optical means includes: an optical unit that converts a light beam from a light source into parallel light or converged light; an optical deflecting device that deflects the light beam that has passed through the optical unit toward an object to be scanned; An image forming lens for forming an image of the reflected light beam on the surface of the object to be scanned, and a flange provided at an end for reinforcing the image forming lens; Providing a flange part
The bent portion, the light beams passing through the ends, the image forming apparatus characterized by a predetermined angle is given in the sub-scanning direction so as not to touch the object to be scanned.