JP2000267036A - Scanning optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize an optical system by bringing an image forming lens system close to a rotary polygon mirror. SOLUTION: Laser light beams L1 emitted from a semiconductor laser 1 being a light source are deflected and scanned by the rotary polygon mirror 3, and are focusted on a photoreceptor through the image forming lens system including a lens 4a and the like. A notched part C1 is formed by partially chamfering the end part of the lens 4a since the optical path of the beam L1 made incident on the mirror 3 is intercepted when the lens 4a is made to approach the mirror 3 in order to make the device compact. Besides, a part left at the lower side of the notched part C1 is used for constituting a reference surface 4x engaged with a positioning pin 11 erected at an optical box.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning optical device used for an image forming apparatus such as a laser beam printer and a laser facsimile.

[0002]

2. Description of the Related Art A scanning optical device used in an image forming apparatus such as a laser beam printer or a laser facsimile irradiates a light beam such as a laser beam onto a reflecting surface of a rotary polygon mirror and performs deflection scanning by high-speed rotation of the rotary polygon mirror. I do. The scanning light obtained in this manner is formed on a photoconductor on a rotating drum to form an electrostatic latent image, and then the electrostatic latent image on the photoconductor is visualized into a toner image by a developing device. Is transferred onto a recording medium such as recording paper, sent to a fixing device, and the toner on the recording medium is heated and fixed to perform printing.

[0003] Figure 4 shows an optical scanning device according to a conventional example, which are linear light source unit that the unit of the semiconductor laser 101 and collimator lens 101a, a laser beam L ₀ of the parallel light beam generated therefrom It focused on the cylindrical lens 102, a rotary polygon mirror 103 for deflecting and scanning the laser light condensed into a linear shape, an imaging lens system for imaging the scanning light on the photoconductor surface of the rotary drum D ₀ 104 Etc. Rotating polygon mirror 103 and imaging lens system 1
04 and the like are housed in the optical box 110, and the light source unit is mounted on the side wall of the optical box 110.

The upper opening of the optical box 110 is
After all the necessary parts are incorporated in the inside, it is closed by a lid (not shown).

A laser beam L ₀ generated from a semiconductor laser 101 is collimated by a collimator lens 101 a, and is rotated by a cylindrical lens 102.
03 is linearly condensed on the reflecting surface of, through the imaging lens system 104, it is taken out toward the window of the optical box 110 to the rotary drum D _0. Such scanning light forms an image on the photosensitive member on the rotary drum D ₀ and, the now accompanied in the sub scanning by rotation of the rotary drum D ₀ and the main scanning by the rotating polygon mirror 103 to form an electrostatic latent image.

A charging device for uniformly charging the surface of the photoreceptor is provided around the photoreceptor, a visualization device for visualizing an electrostatic latent image formed on the surface of the photoreceptor into a toner image, A transfer device or the like for transferring the toner image to a recording medium such as a recording paper is provided.
Is recorded on a recording sheet or the like corresponding to the light beam in which is generated.

The motor 10 for rotating the rotating polygon mirror 103
Reference numeral 3a denotes a rotor which is integral with the rotary polygon mirror 103 and is opposed to a stator on the motor substrate 103b.

If there is an error in the division of the reflection surface of the rotary polygon mirror 103, the timing at which the scanning information is repeatedly written is deviated. And
The light is introduced into the BD sensor 106b via the condenser lens 106a. The scanning light detected by the BD sensor 106b is converted into a trigger signal in a processing circuit (not shown) and introduced into the semiconductor laser 101. Semiconductor laser 10
1 starts write modulation based on image information transmitted from a host computer (not shown) after receiving a trigger signal.

The imaging lens system 104 includes a spherical lens 104
a and a toric lens 104b, and has a so-called fθ function of forming the scanning light of the rotating polygon mirror 103 on the photosensitive member as described above and making the scanning speed of the resulting point image uniform.

The lenses 104a and 104b are fixed to the optical box 110 after being strictly positioned with respect to the optical path of the scanning light as follows.

That is, with respect to positioning members such as positioning pins and abutting members provided on the bottom surface and partition walls of the optical box 110, positioning portions formed on the flanges at the bottom of the lenses 104a and 104b and the side surfaces at both ends. , The positioning in each direction such as the optical axis direction, the adjustment of the inclination angle (θ-axis direction), and the like are strictly performed, and then both ends of each of the lenses 104a and 104b are moved to the optical box Fix to 110.

[0012]

However, according to the above-mentioned prior art, generally, of the two lenses of the imaging lens system, the one closer to the rotary polygon mirror has a positioning portion at the end portion of the light source. It is arranged near the unit. However, if the imaging lens system is arranged close to the rotating polygon mirror for miniaturization of the optical box or the like, the end of the lens is placed on the optical path of laser light (incident light) generated from the light source unit toward the rotating polygon mirror. Parts interfere. Therefore, the so-called chamfering of the end of the lens must be performed to avoid interference with the optical path of the incident light. However, the end of the lens is used as a positioning portion as described above. There is an unresolved issue that will not be possible.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned unresolved problems of the prior art, and has an advantage in that the degree of freedom of arrangement of an imaging lens system can be increased and the miniaturization of an optical box or the like can be greatly promoted. It is an object of the present invention to provide a high-performance scanning optical device.

[0014]

In order to achieve the above object, a scanning optical apparatus according to the present invention comprises a light source for generating a light beam, a deflection scanning means for deflecting and scanning the light beam, and a deflection scanning means. An imaging lens system including at least one lens that forms an image of the light beam on an imaging surface through the lens, and positioning means for positioning the imaging lens system with respect to a housing; A notch is provided at one end of the lens of the system so as to leave a positioning portion that engages with the positioning means, and the light beam is incident on the deflection scanning means through the notch. It is characterized by comprising.

It is preferable that the positioning portion left below the cutout portion of the lens is configured to engage with the positioning pin of the positioning means.

Preferably, the positioning portion left above the cutout portion of the lens is configured to engage with a spring member of the positioning means.

Preferably, the lens is made of a synthetic resin.

When the deflection scanning means is brought closer to the imaging lens system in order to reduce the size of the optical box or the like, the light beam incident on the deflection scanning means from the light source may be blocked by the end of the lens of the imaging lens system. For this reason, a notch for chamfering the end of the imaging lens system is provided.

Without chamfering the entire end of the lens,
Since the chamfering is performed so as to partially cut off a positioning portion such as a reference surface provided at the end of the lens, there is no need to change the arrangement of the positioning pins and the like of the positioning means. That is, it is possible to avoid interference with the light beam while securing the lens positioning portion.

The imaging lens system can be brought close to the deflection scanning means without changing the arrangement of the lens positioning section and the like, and the degree of freedom in design is increased. by this,
The size of the optical box and the like can be greatly reduced.

If the lens is made of a synthetic resin, it is not necessary to perform a cutting process for partially chamfering the end of the lens, so that an increase in the cost of parts can be avoided.

[0021]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment, in which a semiconductor laser 1 as a light source and a collimator lens 1 are shown.
a light source unit unitized a, now the generated cylindrical lens 2 the laser beam L ₁ is condensed into a linear shape is the light beam of the parallel light beam, a deflection for deflecting and scanning the laser light condensed into a linear shape Rotating polygon mirror 3 as scanning means
And an image forming lens system 4 for forming an image of the scanning light on a photoreceptor which is an image forming surface on the rotating drum. The rotating polygon mirror 3 and the imaging lens system 4 are housed in an optical box 10 serving as a housing.
The light source unit is mounted on the side wall of the optical box 10 or the like.

The upper opening of the optical box 10 is closed by a lid (not shown) after all necessary parts are incorporated in the optical box 10.

Laser light L generated from semiconductor laser 1
₁ is collimated by a collimator lens 1a, linearly condensed by a cylindrical lens 2 on a reflection surface of a rotary polygon mirror 3, passes through an imaging lens system 4 and a folding mirror 5, and passes from a window of an optical box 10 to a rotating drum. It is taken out. The scanning light imaged on the photoreceptor on the rotating drum in this way forms an electrostatic latent image with the main scanning by the rotating polygon mirror 3 and the sub-scanning by the rotation of the rotating drum.

In the periphery of the photoreceptor, a charging device for uniformly charging the surface of the photoreceptor, a visualization device for visualizing an electrostatic latent image formed on the surface of the photoreceptor into a toner image, A transfer device or the like for transferring the toner image to a recording medium such as recording paper is provided, and by these operations, recording information corresponding to the light beam generated by the semiconductor laser 1 is printed on recording paper or the like.

The motor for rotating the rotary polygon mirror 3 is such that a rotor integrated with the rotary polygon mirror 3 is opposed to a stator fixed to the motor substrate 3a.

If there is an error in the division of the reflection surface of the rotating polygon mirror 3, the timing at which the scanning information is repeatedly written is shifted. Therefore, the scanning light of the rotating polygon mirror 3 is reflected and separated by the BD mirror 6 at the end in the main scanning direction. Then, the light is introduced into the BD sensor 7b via the condenser lens 7a. BD sensor 7
The scanning light detected by b is converted into a trigger signal by a processing circuit (not shown) and introduced into the semiconductor laser 1. After receiving the trigger signal, the semiconductor laser 1 starts write modulation based on image information transmitted from a host computer (not shown).

The imaging lens system 4 includes two lenses 4a, 4
b, and has a so-called fθ function for forming the scanning light of the rotary polygon mirror 3 on the photosensitive member as described above and making the scanning speed of the resulting point image uniform.

Each of the lenses 4a and 4b is strictly positioned with respect to the optical path of the scanning light as described below.
Fixed to

That is, the center provided on the bottom flange of the lens 4a, which is a spherical lens, is positioned with respect to the positioning pin 11 and the contact member 12, which are positioning means provided on the bottom surface of the optical box 10, the partition wall, and the like. By engaging or abutting positioning portions such as projections and reference surfaces formed on the side surfaces of the respective ends, positioning in the optical axis direction and the adjustment of the tilt angle (θ-axis direction) are strictly performed. Then, both ends of the lens 4a are fixed using an adhesive or a spring.
The positioning of the lens 4b, which is a toric lens, is performed similarly.

The irradiation position of the scanning optical device is adjusted by the optical box 1.
The positioning is performed by the positioning pins 8 and 9 of the positioning member attached to the position 0. The positioning pin 8 fits into a guide hole 10a inside the optical box 10, and the positioning pin 9 fits into a guide hole 10b provided outside the optical box 10. X of scanning optical device
The adjustment of the irradiation position in the direction (optical axis direction) is performed by moving the positioning pin 8 along the guide hole 10a in the X direction. The adjustment of the scanning optical device in the θ direction is performed by:
The rotation is performed by moving the positioning pin 9 along the guide hole 10b in the θ direction.

[0032] Since the lens 4a of the imaging lens system 4 is disposed in the vicinity of the rotary polygon mirror 3, the laser beam incident on the polygon mirror 3 (the incident light) L ₁ is interfering with the end portion of the lens 4a I will. Therefore, in order to avoid such interference, it is necessary to chamfer the end of the lens 4a to avoid the interference with the incident light.
There is no reference plane for positioning in the optical axis direction of a, and it is impossible to abut against the positioning pins 11 provided on the optical box 10 for positioning.

[0033] Therefore, as shown in FIG. 2, an end portion of the lens 4a is chamfered only the lens central portion which passes through the laser beam L _1, the notch C ₁ cut partially to leave the upper and lower portions of the lens 4a The provision of the reference surface 4x, which is a positioning portion for contacting the positioning pin 11, is ensured.

According to the present embodiment, even if the lens of the imaging lens system is brought close to the rotating polygonal mirror in order to reduce the size of the optical box or the like, the end of the lens remains in the optical path of the laser light incident on the rotating polygonal mirror. The degree of freedom in designing the optical system is greatly expanded without interference of the parts.

As a result, a compact and high-performance scanning optical device can be realized.

If a molded lens made of a synthetic resin is used as the lens of the imaging lens system, cutting for local chamfering of the end is unnecessary, which can contribute to a reduction in parts cost.

FIG. 3 shows a second embodiment. This takes into account the recycling of equipment that has recently attracted attention. In the first embodiment, after positioning the lens of the imaging lens system in the optical box, the lens end provided with the cutout portion must be fixed by bonding. The reason is that it is difficult in design to arrange a holding member such as a spring on the opposite side of the reference surface in order to maintain a state in which the reference surface of the lens end and the positioning pin of the optical box are in contact with each other. The presence of adhesives is inappropriate for recycling.

Therefore, the lens 24a of the imaging lens system is configured to be fixed to the optical box 30 without bonding.
That is, the thick portion H between the local surface opposite to the reference surface 24x left below the by chamfered notch C ₂ of the lens 24a, to the value distance given between the two surfaces The optical box 30 is provided with positioning pins 31a and 31b so as to sandwich the thick portion H. The positioning pins 31a and 31b position the lens 24a in the optical axis direction. Also, the lens 24a
To fixing the vertical position, the spring 33 is brought into contact with the positioning portion left on the upper side of the cutout portion C ₂ of the lens 24a, to press the lens 24a downward.

That is, the two positioning pins 31 and 32
And a spring 33, the lens 24a
To fix. The opposite end of the lens 24a is fixed using a spring 34 as in the conventional example.

[0040]

Since the present invention is configured as described above, it has the following effects.

It is possible to avoid trouble when the rotating polygon mirror and the imaging lens system are brought close to each other, and to greatly increase the degree of freedom of arrangement of the imaging lens system. This can promote downsizing and high performance of the device.

[Brief description of the drawings]

FIG. 1 is a plan view showing a scanning optical device according to a first embodiment.

2A and 2B show a lens of an imaging lens system of the apparatus of FIG. 1, wherein FIG. 2A is a partial cross-sectional plan view, and FIG. 2B is a partial perspective view showing an end provided with a notch.

3A and 3B show a lens of an imaging lens system according to a second embodiment, wherein FIG. 3A is a perspective view and FIG. 3B is an end view.

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

[Explanation of symbols]

 Reference Signs List 1 semiconductor laser 2 cylindrical lens 3 rotary polygon mirror 4 imaging lens system 4a, 4b, 24a lens 4x, 24x reference plane 8, 9, 11, 31a, 31b positioning pin 10, 30 optical box 33, 34 spring

Claims (4)

[Claims] A light source for generating a light beam; deflection scanning means for deflecting and scanning the light beam; and at least one lens for imaging the light beam on an imaging surface via the deflection scanning means. An imaging lens system, and positioning means for positioning the imaging lens system with respect to the housing, such that a positioning portion engaging with the positioning means is left at one end of the lens of the imaging lens system. A scanning optical device, wherein the light beam is incident on the deflection scanning means through the notch. 2. The scanning optical apparatus according to claim 1, wherein a positioning portion left below the cutout portion of the lens is configured to engage with a positioning pin of the positioning means. 3. The scanning optical device according to claim 1, wherein the positioning portion left above the cutout portion of the lens is configured to engage with a spring member of the positioning means. 4. The scanning optical device according to claim 1, wherein the lens is made of a synthetic resin.