JP2001100137A - Scanning optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To assemble cylindrical lens or a composite lens including it in an optical box. SOLUTION: The side face 2a of a cylindrical lens 2 is made to abut against an optical-axis-directional reference part 11 stood on the bottom wall of an optical box 10 and the cylindrical lens 2 is slid on a pedestal 12 to adjust the focus of a spot image formed on a rotary drum with laser light; and the cylindrical lens 2 is fixed to the optical box 10 by using a spring 13 which presses the lens against the reference part 11 and pedestal 12 from two directions. It is easy to disassemble and recycle the cylindrical lens 2 and freely readjust it as compared with a case wherein the cylindrical lens 2 is permanently fixed by using an adhesive.

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 digital copying machine.

[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 digital copying machine irradiates a light beam such as a laser beam onto a reflecting surface of a rotary polygon mirror and deflects the light by rotating the rotary polygon mirror at high speed. Scan. 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.

FIG. 4 shows a scanning optical device according to a conventional example, which comprises a light source unit in which a semiconductor laser 101 and a collimator lens 101a are unitized, and a laser beam of a parallel light beam generated from the light source unit. a cylindrical lens 102 to light, a rotating polygon mirror 103 for deflecting and scanning the laser light condensed into a linear shape, an imaging lens for imaging the scanning light to the photosensitive member surface of the rotary drum D ₀ 10
4, 105, etc. The rotating polygon mirror 103 and the imaging lenses 104 and 105 are housed in an optical box 110, and the light source unit is mounted on a side wall of the optical box 110.

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

[0005] Laser light generated from the semiconductor laser 101 is collimated by a collimator lens 101a, condensed linearly by a cylindrical lens 102 on a reflecting surface of a rotary polygon mirror 103, and passed through imaging lenses 104, 105 and the like. 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 shifted. Therefore, the scanning light of the rotary polygon mirror 103 is reflected and separated by the BD mirror 106 at the end in the main scanning direction. And
It is introduced into the BD sensor 107. The scanning light detected by the BD sensor 107 is converted into a trigger signal in a processing circuit (not shown) and introduced into the semiconductor laser 101. After receiving the trigger signal, the semiconductor laser 101 starts write modulation based on image information transmitted from the host computer.

The imaging lenses 104 and 105 have a so-called fθ function of making the scanning speed of a point image obtained by forming the scanning light of the rotating polygon mirror 103 on the photosensitive member uniform as described above.

The cylindrical lens 102 is disposed so that the center of the lens coincides with the optical axis of the semiconductor laser 101 of the light source unit, and is provided on the bottom wall of the optical box 110 in the optical axis direction. One end of the cylindrical lens 102 is brought into contact with the lens to adjust the position in the optical axis direction.

The bottom surface of the cylindrical lens 102 is in contact with an upwardly facing pedestal 112 of the optical box 110.

[0012] spot diameter of the photoreceptor point image can be imaged on a laser beam deflected and scanned by the rotary polygon mirror 103 onto a rotating drum D ₀ is the shape error and optical components alone in the optical box 110, the optical The deviation from the design standard value occurs due to a dimensional error or the like when assembling the component. Therefore, by adjusting the position of the cylindrical lens 102 in the optical axis direction, focus adjustment for adjusting the spot diameter on the photoconductor in the sub-scanning direction to a standard value is performed.

[0013] In this operation, one end of the cylindrical lens 102 in a state pressed against the reference portion 111 of the optical box 110, while sliding the cylindrical lens 102 on the base 112 of the optical box 110, the rotary drum D ₀ above Is observed, and at a position where the spot diameter is minimized, the cylindrical lens 1 is irradiated with a light-curing adhesive or the like.
02 is bonded and fixed to the optical box 110.

[0014]

However, according to the above-mentioned prior art, since the cylindrical lens is bonded and fixed to a housing such as an optical box as described above, it is necessary to disassemble the apparatus or recycle parts. It is also difficult to readjust the cylindrical lens, and as a result, there is an unsolved problem that the component cost and the assembly cost are high.

The present invention has been made in view of the above-mentioned unresolved problems of the prior art, and uses an elastic member for assembling a cylindrical lens to a housing such as an optical box to disassemble or recycle the apparatus. It is an object of the present invention to provide a scanning optical device which can easily perform the above-mentioned operations and can greatly improve the workability of assembling and re-adjustment of a cylindrical lens.

[0016]

In order to achieve the above object, a scanning optical apparatus according to the present invention comprises a light source, a lens for condensing a light beam generated from the light source linearly on a reflection surface of a deflector, An imaging optical system that forms an image of the scanning light of the deflector on an imaging surface, and an assembling unit that assembles the lens to a housing,
An elastic member for pressing the lens against a reference portion and a pedestal provided on the housing is provided.

Preferably, the reference portion of the housing is for adjusting the position of the cylindrical lens in the optical axis direction.

The reference portion of the housing may be for adjusting the position of the BD lens in the optical axis direction.

The elastic member preferably has a first pressing portion for pressing the lens against the reference portion, and a second pressing portion for pressing the lens against the base.

It is preferable that the elastic member is provided with a saw blade-shaped portion that engages with the end surface of the lens.

It is preferable that the end surface of the lens is provided with a streak-like unevenness which meshes with the saw blade-shaped portion of the elastic member.

The streak of the lens is 0.1 to 2 mm
It is good to be formed with the pitch of.

[0023]

When a cylindrical lens or a compound lens combining a cylindrical lens and a BD lens is assembled to a housing such as an optical box, if the lens is permanently fixed using an adhesive, parts cannot be recycled. Re-adjustment becomes impossible. Therefore, as an assembling means of the lens, an elastic member such as a spring that elastically presses the lens against the reference portion and the pedestal of the housing from two directions is used.

The elastic member that presses the lens against the reference portion and the pedestal of the housing not only allows the lens to be firmly fixed, but also allows the elastic member and the lens to be easily removed, and that both can be reused extremely easily. Further, since the lens is not permanently fixed as in the case of using an adhesive, the lens can be readjusted, the initial assembling work is easy, and the working efficiency is high.

By forming a streak-like unevenness on the end face of the lens and providing a saw blade-shaped portion to be engaged with the same on the elastic member, the elastic member is prevented from slipping on the end face of the lens, and is fixed more firmly. it can.

[0026]

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

FIG. 1 shows a main part of a scanning optical device according to an embodiment. A cylindrical lens 2 as a lens is provided with a semiconductor laser 1 as a light source of a light source unit.
(See FIG. 3). The cylindrical lens 2 is disposed on the optical axis direction reference portion 11 erected on the bottom wall of the optical box 10 as a housing. The position adjustment in the optical axis direction is performed by abutting the side surface 2a.

The bottom surface of the cylindrical lens 2 is
The optical box 10 is brought into contact with an upwardly facing pedestal 12.

As will be described later, a rotary polygon mirror 3 which is a deflector
The spot diameter of a point image can be imaged on the photosensitive member is deflected and scanned laser beam is a imaging surface on the rotating drum D ₁ is the shape error and optical components alone of the optical box 10 allows the optical components The deviation from the design standard value occurs due to a dimensional error in assembling. Therefore, by adjusting the position of the cylindrical lens 2 in the optical axis direction, focus adjustment for adjusting the spot diameter in the sub-scanning direction on the photoconductor to a standard value is performed.

In this operation, while rotating the cylindrical lens 2 on the pedestal 12 of the optical box 10 with the side surface 2a of the cylindrical lens 2 pressed against the reference portion 11 of the optical box 10, the rotating drum D ₁ The upper spot diameter is observed, and the cylindrical lens 2 is fixed to the optical box 10 by a spring 13 as an elastic member (assembly means) at a position where the spot diameter becomes minimum.

A spring 13, which is an elastic member for pressing the cylindrical lens 2 against the reference portion 11 and the pedestal 12 of the optical box 10 from two directions, is provided on the end surface 2 of the top of the cylindrical lens 2.
b, a second pressing portion 13b abutting on the side surface of the cylindrical lens 2, and a support portion 13c screwed to the pedestal 12 of the optical box 10, The support 13c of the spring 13 is provided with an elongated hole 13d, and the support 13c of the spring 13 is fastened to the pedestal 12 by a screw 13e penetrating the elongated hole 13d.

The tip of the first pressing portion 13a of the spring 13 has a saw blade shape so as to mesh with a stripe-shaped unevenness 2c having a pitch of 0.1 to 2 millimeters (mm) provided on an end surface 2b of the cylindrical lens 2. A portion 13f is provided.

The spring 13 firmly fixes the focus adjusted cylindrical lens 2 to the optical box 10 by such a meshing structure. The relative position between the cylindrical lens 2 and the spring 13 after the focus adjustment is determined by the optical box 1.
Slot 1 through which screw 13e for fastening spring 13 is inserted
Fine adjustment is possible within the range of 3d.

To adjust the focus, the pressing force of the spring 13 is released, and the cylindrical lens 2 on the base 12 is moved to the reference portion 11.
This is performed by sliding along the guide shape of the reference portion 11 in a state where the reference portion 11 abuts. After adjusting the focus, the spring 13
The first and second pressing portions 13a and 13b are respectively brought into contact with the cylindrical lens 2, and the screws 13e are tightened.
The cylindrical lens 2 is pressed against the reference portion 11 and the pedestal 12 by the pressing force of the spring 13 in two directions. Is firmly fixed. At this time, the elongated hole 13 through which the screw 13e passes
The relative position between the spring 13 and the cylindrical lens 2 can be finely adjusted within the range allowed by d, and the engagement between the saw blade-shaped portion 13f of the spring 13 and the unevenness 2c of the cylindrical lens can be adjusted.

According to the present embodiment, since the cylindrical lens is fixed to the optical box by a spring without using an adhesive, it is extremely easy to remove the cylindrical lens for recycling of device parts. Yes, and there is a remarkable advantage that any number of adjustments can be made even after the focus adjustment is completed and the cylindrical lens is fixed.

Further, by using a spring for holding the cylindrical lens from two directions, the cylindrical lens can be firmly and accurately assembled to the optical box, and the work efficiency of the initial assembly is greatly improved. This can contribute to higher performance and lower cost of the device.

FIG. 2 shows a modification. This is because the cylindrical lens 22a is connected to another lens of the scanning optical system, for example, a BD for detecting a scanning start signal (trigger signal).
This is a case where the compound lens 22 integrated with the lens 23 is used.

The pedestal 32 of the optical box 30 is a guide-shaped portion which is a groove-shaped reference portion extending not in the optical axis direction of the cylindrical lens 22a indicated by the dashed line α but in the optical axis direction of the BD lens 23 indicated by the dashed line β. 31 and the compound lens 2
At the bottom of 2, a rib-shaped portion is provided which engages with the guide-shaped portion 31 of the optical box 30.

The bottom surface of the compound lens 22 is brought into contact with the pedestal 32, and the rib-shaped portion of the compound lens 22 is engaged with the guide-shaped portion 31 to position the BD lens 23 in the optical axis direction. First and second pressing portions 13a, 1
The point of contacting the supporting portion 3b with the optical box 30 with the screw 13e and the point of engaging the saw blade-shaped portion 13f of the spring 13 with the stripe-shaped unevenness 22c of the compound lens 22 are the same as those of the apparatus of FIG. The same is true.

As described above, even if the compound lens 22 is a combination of a cylindrical lens and another lens, the spring 1
3 enables firm and accurate fixing.

FIG. 3 shows the entire scanning optical apparatus, which comprises a light source unit combining a semiconductor laser 1 for generating a light beam (light beam) such as a laser beam and a collimator lens 1a, and a light beam unit as described above. And a cylindrical lens 2 which is a lens for linearly condensing the light beam on the reflection surface of the rotary polygon mirror 3, and deflects and scans the light beam by the rotation of the rotary polygon mirror 3. 4,
After five such focusing on the photosensitive member on the rotary drum D _1. Forming lens 4 and 5 spherical lens, a toric lens or the like, has a so-called fθ function of correcting the scanning speed of the point image formed on the photosensitive member on the rotary drum D _1.

When the rotating polygon mirror 3 is rotated by the motor 3a on the motor substrate 3b, the reflection surface of the rotating polygon mirror 3
Rotates at a constant speed around the axis of. As described above, the angle between the optical path of the light beam generated from the semiconductor laser 1 and collected by the cylindrical lens 2 and the normal to the reflection surface of the rotary polygon mirror 3, that is, the angle of incidence of the light beam on the reflection surface is Changes over time with the rotation of the rotating polygon mirror 3,
To change Similarly, reflection angle, the point image can light beam is focused on the photosensitive member to move in the axial direction of the rotary drum D ₁ (main scanning direction).

The imaging lenses 4 and 5 focus the light beam reflected by the rotary polygon mirror 3 on a photosensitive member into a point image having a predetermined spot shape, and scan the point image in the main scanning direction. Is designed to keep the speed constant.

The point image formed on the photoreceptor is
Main scanning by rotation and rotating drum D ₁ Around its axis
Forming an electrostatic latent image with sub-scanning by rotation
I do.

Around the photosensitive member, a charging device for uniformly charging the surface of the photosensitive member, a developing device for developing an electrostatic latent image formed on the surface of the photosensitive member into a toner image, A transfer device or the like for transferring the toner image to recording paper is provided, and recording information by a light beam generated from the semiconductor laser 1 is printed on recording paper or the like.

The detection mirror 6 reflects the light beam on the upstream side in the main scanning direction from the optical path of the light beam incident on the write start position of the recording information on the surface of the photoreceptor, receives the light beam via a lens, and has a photodiode or the like. The light is introduced to the light receiving surface of the element 7. The light receiving element 7 outputs a scan start signal for controlling a write start position (write start position) when the light receiving surface is irradiated with the light beam.

The semiconductor laser 1 generates a light beam corresponding to a signal given from a processing circuit for processing information from a host computer. The signal given to the semiconductor laser 1 corresponds to information to be written on the photoconductor, and the processing circuit generates a signal representing information corresponding to one scanning line which is a locus formed by a point image formed on the surface of the photoconductor. Is given to the semiconductor laser 1 as one unit. This information signal is transmitted in synchronization with a trigger signal provided from the light receiving element 7.

The rotating polygon mirror 3, the imaging lenses 4, 5 and the like are housed in an optical box 10, and the light source unit and the like are stored in the optical box 10.
Attached to the side wall. Rotating polygon mirror 3 in optical box 10,
After the imaging lenses 4 and 5 are assembled, a lid (not shown) is attached to the upper opening of the optical box 10.

[0049]

Since the present invention is configured as described above, the following effects can be obtained.

After adjusting the position of the cylindrical lens or the compound lens including the cylindrical lens, the lens is fixed to the optical box by an elastic member.
Recycling of parts is easy and, in addition, the efficiency of readjustment work and initial assembly work can be greatly improved. Thus, an inexpensive and high-performance scanning optical device can be realized.

[Brief description of the drawings]

FIG. 1 is a partial perspective view showing a main part of a scanning optical device according to an embodiment.

FIG. 2 is a partial perspective view showing a modification.

FIG. 3 is a diagram illustrating the entire scanning optical device.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor laser 2, 22a Cylindrical lens 2c, 22c Concavo-convex 3 Rotating polygon mirror 4, 5 Imaging lens 10, 30 Optical box 11 Reference part 12, 32 Pedestal 13 Spring 13a, 13b Pressing part 13f Saw blade shape part 22 Composite lens 31 Guide shape part

Claims (9)

[Claims] 1. A light source, a lens that linearly condenses a light beam generated from the light source on a reflection surface of a deflector, and an imaging optical system that forms scanning light of the deflector on an imaging surface. Wherein the assembling means for assembling the lens to the housing includes an elastic member for pressing the lens against a reference portion and a pedestal provided in the housing. . 2. The scanning optical device according to claim 1, wherein the lens is a cylindrical lens. 3. A lens comprising a cylindrical lens and a BD.
2. The scanning optical device according to claim 1, wherein the scanning optical device is a compound lens obtained by combining lenses. 4. The scanning optical device according to claim 2, wherein the reference portion of the housing is for adjusting the position of the cylindrical lens in the optical axis direction. 5. The scanning optical device according to claim 3, wherein the reference portion of the housing is for adjusting the position of the BD lens in the optical axis direction. 6. The elastic member according to claim 1, wherein the elastic member has a first pressing portion for pressing the lens against the reference portion, and a second pressing portion for pressing the lens against the pedestal. The scanning optical device according to any one of the preceding claims. 7. The scanning optical device according to claim 1, wherein the elastic member is provided with a saw blade-shaped portion that engages with an end surface of the lens. 8. The scanning optical device according to claim 7, wherein the end surface of the lens is provided with a streak-like unevenness that meshes with the saw blade-shaped portion of the elastic member. 9. The lens has a streak-like unevenness of 0.1 to 2 m.
9. The semiconductor device according to claim 8, wherein said plurality of pitches are formed at a pitch of m.
The scanning optical device according to claim 1.