JP2001147396A - Scanning optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the rattling of an optical lens, to miniaturize a scanning optical device and to reduce cost, while keeping the image quality. SOLUTION: A fixed fitting tool restraint to fixed structure parts 21 and 22 depresses the end parts 15b and 15c of a scanning lens 15 with respect to bearing surfaces 31 and 32 at depression points P3 and P4 and depresses them with respect to bearing surfaces 33 and 34 at depression points P3 and P4. In a length in the vertical direction with respect to a scanning plane, the left bearing surface 31 is made to be relatively shorter than the right bearing surface 32. The long bearing surface 32 is made to cover the whole length of the short direction of the scanning lens 15. The short bearing surface 31 is made to be not more than one third of the long bearing surface 32. The short bearing surface 31 is arranged near the center of the short direction of the scanning lens 15. The positions of the depression points P1 to P4 are set substantially at the center of the bearing surfaces 31 to 34. The attitude of the scanning lens 15 is decided by the long bearing surface 32 and it will not be affected by the short bearing surface 31.

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 light source unit, a cylinder lens, a deflection scanning unit, a scanning lens, a folding mirror, and the like are arranged in a box of a scanning optical device of this type so that a light beam scans on a photosensitive drum. In addition, a reflection mirror, a light detection unit, and the like are arranged so as to detect the light beam. The cylinder lens, the deflection scanning unit, the scanning lens, the folding mirror, the reflection mirror, and the light detection unit are mounted on a box and fixed by screws or other fixing means.

As shown in FIGS. 10 and 11, a light beam L1 from a light source unit is deflected by a polygon mirror 1 of a deflection scanning unit to become a light beam L2.
Is transmitted. This type of scanning lens 2 is provided with a lens portion 2a that is in the scanning range of the light beam L2 and transmits the light beam L2, and ends 2b and 2c located outside the lens portion 2a.

In many cases, the ends 2b and 2c of the scanning lens 2 are fixed to the fixing structures 3 and 4 by fixing metal fittings, and the position and posture of the scanning lens 2 are determined.
For this reason, the fixed structure portions 3 and 4 have seating surfaces 3a and 4a substantially orthogonal to the scanning plane for determining the inclination of the scanning lens 2,
Seat surfaces 3b and 4b on which the scanning lens 2 is mounted are provided substantially in parallel with a scanning plane for determining the height of the scanning lens 2 so as to sandwich the center of the scanning lens 2.

When the box is made of synthetic resin, the seat surface 3
a, 4a and the bearing surfaces 3b, 4b are integrally formed into a box by an injection molding machine. The scanning lens 2 has reference surfaces 2d and 2e pressed against the bearing surfaces 3a and 4a, respectively, and has reference surfaces 2f and 2g pressed against the bearing surfaces 3b and 4b, respectively. And the scanning lens 2
Are pressed against the seating surfaces 3a, 4a at the pressing points P1, P2 by fixing fittings made of springs, and pressed against the seating surfaces 3b, 4b at the pressing points P3, P4, so that the fixing structures 3, 4
Fixed to

At this time, if the length of the seating surfaces 3a, 4a for determining the inclination of the scanning lens 2 is increased, the inclination of the scanning lens 2, that is, the error of the tilt angle can be suppressed.
The length of “a” is made as large as possible, specifically, a value close to the maximum dimension of the scanning lens 2 in the lateral direction.

[0007]

However, in the above conventional example, as shown in FIGS.
When the inclination angles of a and 4a are different, the initial posture of the scanning lens 2 changes as shown in FIGS. 13A and 13B due to vibration or the like, and the scanning lens 2 is likely to rattle. . That is, as shown in FIG. 12A, one reference surface 2d of the scanning lens 2 is adjusted and fixed in accordance with the seating surface 3a of the fixed structure portion 3, and as shown in FIG. The surface 2 e may not be along the bearing surface 4 a of the fixed structure 4.

When this state changes so that the reference surface 2e of the scanning lens 2 follows the seating surface 4a of the fixed structure portion 4 as shown in FIG. 13B, the scanning lens 2 as shown in FIG. The reference surface 2d changes so as not to be along the bearing surface 3a of the fixed structure portion 3.

Such rattling occurs not only in the scanning lens 2 but also in all optical lenses whose inclination is restricted by the seating surfaces on both sides. For this reason, in the conventional example, this is one cause of the occurrence of image defects due to spot defects and the like.

When the scanning lens 2 is disposed close to the polygon mirror 1 to reduce the size of the scanning optical device as shown in FIG. The movement is interrupted, and it is difficult to reduce the size of the scanning optical device.

An object of the present invention is to solve the above-mentioned problems,
It is an object of the present invention to provide a scanning optical device that prevents rattling of an optical lens due to a difference in inclination angle between two seating surfaces that determine the attitude of the optical lens and that can maintain image quality.

Another object of the present invention is to provide a scanning optical apparatus capable of preventing the above-mentioned rattling and allowing the scanning lens to be close to the deflecting scanning means, thereby achieving downsizing and cost reduction. To provide.

[0013]

To achieve the above object, a scanning optical apparatus according to the present invention comprises: a light emitting means for emitting a light beam; a deflection scanning means for deflecting and scanning the light beam from the light emitting means; An optical lens disposed in a box, and two seating surfaces for determining the attitude of the optical lens are provided so as to be substantially perpendicular to a scanning plane on both sides of the center of the optical lens. The lengths of the two seating surfaces are different in a direction substantially perpendicular to the scanning plane.

A scanning optical device according to the present invention comprises: a light emitting means for emitting a light beam; a deflection scanning means for deflecting and scanning the light beam from the light emitting means; and a scanning lens disposed in an optical path, housed in a box. A scanning optical device provided with two seating surfaces for determining a posture of the scanning lens so as to be substantially perpendicular to a scanning plane on both sides of a center of the scanning lens,
The length of the two seating surfaces is made different from each other in a direction substantially perpendicular to the scanning plane, and a notch is formed at one end in the longitudinal direction of the scanning lens to allow a light beam to pass therethrough. Is provided.

A scanning optical device according to the present invention comprises a light emitting means for emitting a light beam, a deflection scanning means for deflecting and scanning a light beam from the light emitting means, and an optical lens arranged in an optical path in a box. A scanning optical device provided with two seating surfaces for determining a posture of the scanning lens so as to be substantially parallel to a scanning plane of the optical lens on both sides of a center of the optical lens, wherein It is characterized in that the lengths of the two seating surfaces are different in the short direction.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a plan view of the first embodiment with a cover removed, and an optical box 11 includes a light source unit 12, a cylinder lens 13, and a deflection scanning unit 1.
4, scanning lenses 15, 16 and folding mirror 17 are arranged, and reflecting mirror 18, light detecting unit 19
Is provided. The light source unit 12 includes a semiconductor laser light source 12a, a collimator lens 12b, and the like.
The deflection scanning unit 14 has a configuration in which a polygon mirror 14a is rotatably supported by a drive motor 14b, and the light detection unit 19 for synchronization detection includes a light detection lens 19a, a sensor 19b, and the like. These cylinder lens 13, deflection scanning unit 14, scanning lens 15, 1
6. The folding mirror 17, the reflection mirror 18, and the light detection unit 19 are assembled to the optical box 11 and fixed by screws or other fixing means.

The light beam L emitted from the light source unit 12
Numeral 1 transmits through the cylinder lens 13 and is compressed in the sub-scanning direction, and forms an image on the rotating polygon mirror 14a. The light beam L2 reflected by the polygon mirror 14a passes through the scanning lenses 15 and 16 and is reflected by the turning mirror 17 to enter the photosensitive drum from the exit port 25 of the optical box 11 to form an image in the form of a spot. Scan at a constant speed on the drum.

Before entering the photosensitive drum, the light beam L2 is reflected by the reflecting mirror 18 upstream of the main scanning direction, enters the light detection unit 19, and determines the recording start timing from the light detection unit 19. An electric signal is output. The image forming apparatus receives an electric signal from the light detection unit 19, and forms and outputs an image in conjunction with the scanning optical device.

Here, both ends of the scanning lens 15 are fixed to the fixing structures 21 and 22 of the optical box 11 by a fixing fitting 2 made of a spring.
The scanning lens 16 is fixed in the same way as the scanning lens 15. That is, as shown in the partial vertical sectional view of FIG. 2, one fixed structure portion 21 has front and rear vertical walls 21a and 21b, and the end of the scanning lens 15 is disposed between the vertical walls 21a and 21b. I have. The fixing bracket 23 is disposed between the scanning lens 15 and the vertical wall 21b, is locked by a locking projection 21c provided on the vertical wall 21b, and exerts a force on the scanning lens.

FIG. 3 is a plan view schematically showing a fixed state of the scanning lens 15, and FIG.
1 and 22 are seating surfaces 31 for determining the inclination of the scanning lens 15,
32 and seating surfaces 33 and 34 for determining the height of the scanning lens 15
Are provided in a convex shape, respectively. Seats 31, 32
Is a surface perpendicular to the scanning plane of the light beam L2,
Reference numerals 3 and 34 are planes parallel to the scanning plane of the light beam L2.

The scanning lens 15 is injection-molded from a synthetic resin material. The scanning lens 15 is fixed to a lens portion 15a for transmitting the light beam L2 from the polygon mirror 14a and fixed structure portions 21 and 22 of the optical box 11 on both sides thereof. End 1
5b and 15c. Further, the scanning lens 15 is provided with reference surfaces 35 and 36 that contact the seat surfaces 31 and 32 and reference surfaces 37 and 38 that contact the seat surfaces 33 and 34, respectively, in a planar shape. Although the seat surfaces 31 to 34 are convex and the reference surfaces 35 to 38 are planar, they may be reversed or both may be convex.

The left seat surface 31 is relatively shorter than the right seat surface 32 in the length in the direction perpendicular to the scanning plane. For example, the length of the long seat surface 32 is set to the length over the entire height direction of the scanning lens 15, and
The length of one is less than or equal to one-third of the length of the long seat surface 32, and the short seat surface 31 is formed so as to be located near the center of the scanning lens 15 in the height direction. Further, the positions of the pressing points P1 to P4 are respectively arranged at substantially the centers of the seating surfaces 31 to 34.

The ends 15b and 15c of the scanning lens 15 are
Fixing fittings 23, 24 locked to fixing structure portions 21, 22
As a result, the seats 31 and 32 are pressed at the pressing points P1 and P2, respectively, and the seats 33 and 34 are pressed at the pressing points P3 and P4, respectively. The pressing force applied to these pressing points P1 to P4 is left and right uniform.

The positions of the pressing points P1 to P4 can be shifted from the center of the seating surfaces 31 to 34 in consideration of the degree of fixing of the scanning lens 15 and the durability against vibration. Further, it is preferable that the right and left pressing forces applied to the pressing points P1 to P4 are made uniform, but it is also possible to make them non-uniform for the same reason.

Further, the longitudinal shape of the long seat surface 32, that is, the surface shape in the direction perpendicular to the scanning plane is preferably a plane as shown in FIG. 5A, but is shown in FIG. 5B. There is no problem even with such a concave surface. However, the convex surface as shown in FIG. 5C should be avoided because the fixing of the inclination of the scanning lens 15 becomes unstable.

On the other hand, since the short bearing surface 31 abuts on the reference surface 35 of the scanning lens 15 to restrict the rotation of the scanning lens 15 in the scanning plane, the surface shape of the short bearing surface 31 is also preferably flat. . However, the surface shape of the short seat surface 31 is not affected by the unevenness as much as the surface shape of the long seat surface 32.

As described above, in the first embodiment, the ratio of the lengths of the bearing surfaces 31 and 32 to the length in the direction perpendicular to the scanning plane is 3: 1, so that the ratio of the moment is also 3: 1. The moment for rotating the scanning lens 15 in the direction in which the short seating surface 31 tilts is smaller than the moment in the same direction generated on the long seating surface 32. Therefore, the inclination angle of the scanning lens 15 can be determined by the long seat surface 32, and the inclination angle of the scanning lens 15 is short due to vibration or the like unless there is a marked difference in the pressing force of the fixing brackets 23 and 24. The scanning lens 15 is not imitated to the optical box 11
Can be fixed without rattling.

Thus, the short seat 31 and the long seat 3
The relative angle of 2 does not need to be severe. Therefore, it is possible to reduce the cost of the mold and to increase the molding speed, thereby reducing the production cost.

FIG. 6 shows a modification in which a long seat surface 32 is divided into two upper and lower seat surfaces 32a and 32b. In this modification, the distance between the seating surfaces 32a and 32b can be considered as the effective length of the seating surface. Therefore, the tilt angle of the scanning lens 15 can be determined according to the angle formed by the seating surfaces 32a and 32b, and the first angle can be determined. The same effect as that of the embodiment can be achieved.

FIG. 7 shows a second embodiment, in which the scanning lens 1 is used.
5 'is provided near the polygon mirror 14a, and the optical box 11'
Has been downsized. Scanning lens 15 'is fixed structure 2
1 ', 22 are fixed via fixing brackets 23', 24. For this reason, the fixing structure 22 and the fixing fitting 24
On the other hand, it is the same as the embodiment of FIG.
Is formed with a cutout portion 21d for passing the light beam L1 compressed in one direction by the cylinder lens 13 toward the polygon mirror 14a without blocking the light beam L1.
The height of 1 'is reduced. Further, the fixing bracket 23 'is also formed in a shape corresponding to the fixing structure 21'.

As shown in FIG. 8 and FIG.
A cutout 15d is formed at the left end 15b of 5 ', and the cutout 15d is formed in a shape and size that does not block the effective diameter of the light beam L1 from the cylinder lens 13. Therefore, the height of the fixed structure portion 21 'is equal to the height of the remaining portion 15e excluding the cutout portion 15d of the scanning lens 15'. Then, the reference surface 35 of the scanning lens 15 ′
Is provided on the remaining portion 15e outside the lens portion 15a.

The reason why the locking portion is provided outside the lens portion 15a is that the fixing structure portion 21 'and the fixing bracket 23' are provided with the light beam L.
The object of the present invention is to prevent the influence of blocking or the like from being brought close to 2 and prevent the lens surface from being distorted due to a partial peculiar shape of the scanning lens 15 '. The height of the normal scanning lens 15 'is 10 to 15 mm, and the diameter of the light beam L1 passing through the scanning lens 15' is 1 to 2 mm.
Has a thickness of about 3 to 4 mm.

The right seat surface 32 on the optical box 11 'side is formed over the entire height of the lens, while the left seat surface 3 is formed.
The position of 1 corresponds to the reference plane 35 of the scanning lens 15 ',
It is formed short at a low position so as not to block the light beam L1. Further, the position of the left seat surface 33 is formed inside the right seat surface 34 in correspondence with the pressing point P3 from above.

The pressing points P1 and P2 correspond to the seat surfaces 31 and 32, respectively.
Are arranged substantially at the center, and the right and left pressing forces applied thereto are also uniform. The pressing point P4 is located at substantially the same position as the long seat surface 32, while the pressing point P3 is the short seat surface 3.
1 inside. The seat surfaces 33 and 34 are arranged on an extension of the pressing direction applied to the pressing points P3 and P4 in the pressing direction.

Also in the second embodiment, the short seat surface 31 and the long seat surface 32 operate in the same manner as in the first embodiment.
The same effect as that of the embodiment can be achieved. In addition, the scanning lens 15 'can be made to approach the polygon mirror 14a without blocking the light beam L1 from the cylinder lens 13 to the polygon mirror 14a.
The depth of 1 'can be reduced by about 15% as compared with the related art, and downsizing can be realized.

Note that the pressing points P1 and P2 are
And the left and right pressing forces applied thereto are made uniform. However, even if the positions of the pressing points P1 and P2 are shifted, the left and right pressing forces can be made non-uniform. In addition, seat surface 3
Although the reference numerals 3 and 34 are arranged on the extension of the pressing direction of the pressing force applied to the pressing points P3 and P4, the positions need not be limited.

In the above description, the seating surface 3 perpendicular to the scanning plane
Although the lengths of the seats 1 and 32 are different, the same effect can be achieved even if the seat surfaces 34 and 35 that are parallel to the scanning plane have different lengths. That is, the scanning lenses 15, 15 '
The reference surfaces 37 and 38 on the bottom surface of the seat 3 are parallel to the scanning plane.
If the seats 33, 34 are configured such that the length of the scanning lenses 15, 15 'in the lateral direction is a combination of a long seating surface and a short seating surface, The attitude of the scanning lenses 15, 15 'follows the angle of the long seat.

In the above-described embodiment, the light detecting lens 19 is used.
This can be applied to other optical lenses such as a.

[0039]

As described above, in the scanning optical apparatus according to the present invention, one of the seat surfaces at both ends for determining the posture of the optical lens is long and the other is short, so that the posture of the optical lens is small. Is determined by the long seat surface, so that the optical lens can be displaced along the short seat surface, that is, rattling of the optical lens can be suppressed, and image quality can be maintained.

Since one of the two seating surfaces is a short seating surface, it is possible to form a notch at one end of the optical lens for transmitting a light beam. For this reason, it becomes possible to arrange the optical lens close to the deflection scanning means,
The size of the box can be reduced.

Furthermore, since it is not necessary to make the accuracy of the relative angle of the seating surface of the box strict, it is possible to reduce the cost of the molding die and to increase the speed of the molding cycle, thereby reducing the production cost.

[Brief description of the drawings]

FIG. 1 is a plan view of a first embodiment with a lid removed.

FIG. 2 is a vertical sectional view of a fixing structure.

FIG. 3 is a plan view illustrating a relationship between a scanning lens and a seat surface.

FIG. 4 is a front view illustrating a relationship between a scanning lens and a seat surface.

FIG. 5 is a cross-sectional view illustrating a shape of a seat surface.

FIG. 6 is a front view illustrating a relationship between a scanning lens and a seat surface according to a modified example.

FIG. 7 is a plan view of the second embodiment.

FIG. 8 is a plan view illustrating a relationship between a scanning lens and a bearing surface.

FIG. 9 is a front view illustrating a relationship between a scanning lens and a seat surface.

FIG. 10 is a plan view illustrating a relationship between a conventional scanning lens and a seat surface.

FIG. 11 is a front view illustrating the relationship between a conventional scanning lens and a seat surface.

FIG. 12 is a cross-sectional view illustrating rattling of a conventional scanning lens.

FIG. 13 is a cross-sectional view illustrating rattling of a conventional scanning lens.

FIG. 14 is a cross-sectional view for explaining miniaturization of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Optical box 12 Light source unit 13 Cylinder lens 14 Deflection scanning unit 14a Polygon mirror 15, 15 ', 16 Scanning lens 15b, 15c End part 15d Notch part 15e Remaining part 19 Light detection unit 19a Light detection lens 31-34 Seat surface 35-38 Reference plane L1, L2 Light beam

Claims (7)

[Claims] A light emitting means for emitting a light beam, a deflection scanning means for deflecting and scanning the light beam from the light emitting means, and an optical lens arranged in an optical path are housed in a box, and the attitude of the optical lens is determined. A scanning optical device provided with two seating surfaces on both sides of a center of the optical lens so as to be substantially perpendicular to a scanning plane, wherein the length of the two seating surfaces is set in a direction substantially perpendicular to the scanning plane. A scanning optical device characterized by being different. 2. The length of the two seats is less than one third of the length of the short seat.
3. The scanning optical device according to claim 1. 3. The scanning optical device according to claim 1, wherein the shorter one of the two seating surfaces is decentered from a lens center in a direction substantially perpendicular to the scanning plane. 4. The scanning optical device according to claim 1, wherein the optical lens is a light detection lens. 5. The scanning optical device according to claim 1, wherein the optical lens is a scanning lens. 6. A light emitting unit for emitting a light beam, a deflection scanning unit for deflecting and scanning the light beam from the light emitting unit, and a scanning lens arranged in an optical path are accommodated in a box, and the attitude of the scanning lens is determined. A scanning optical device provided with two seating surfaces so as to be substantially perpendicular to a scanning plane on both sides of a center of the scanning lens, wherein the length of the two seating surfaces is set in a direction substantially perpendicular to the scanning plane. A scanning optical device, wherein the scanning lens is provided with a notch for allowing a light beam to pass therethrough at one end in a longitudinal direction of the scanning lens, and a short seat surface is provided at a portion other than the notch. 7. A light emitting unit for emitting a light beam, a deflection scanning unit for deflecting and scanning the light beam from the light emitting unit, and an optical lens arranged in an optical path are housed in a box, and the attitude of the optical lens is determined. A scanning optical device comprising two seating surfaces provided on both sides of a center of the optical lens so as to be substantially parallel to a scanning plane of the optical lens, wherein the two seats are arranged in a short direction of the optical lens. A scanning optical device, wherein the lengths of the surfaces are different.