JP3492175B2 - Optical element, mold for molding the optical element, method for molding the optical element, and optical device having the optical element - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical element, a molding die for the optical element, a method for molding the optical element, and an optical device having the optical element.

[0002]

2. Description of the Related Art Conventionally, optical elements having a special lens shape such as an aspherical surface have been mass-produced by molding, taking advantage of high productivity and low cost.

A long lens called an f theta lens is used in an optical device used in a scanning optical system of a laser printer or a digital copying machine. In addition, a long lens called a bar lens arranged in a line is used in a reading optical system of a copying machine or a facsimile. The long lens generally means a lens whose length in the longitudinal direction is about 5 times or more the length in the other two lateral directions.

FIG. 20 is a diagram showing an optical device used in a scanning optical system of a conventional laser printer or digital copying machine.

In FIG. 20, an optical device 111 includes a semiconductor laser 101 as a light source and a collimator lens 102.
A cylindrical lens 103, a rotary polygon mirror 104 that scans a laser beam, a first f theta lens 105 located upstream of the rotary polygon mirror 104, and a rear stage of the first f theta lens 105. The second f theta lens 106 and the folding mirror 107 are provided. The f theta lenses 105 and 106 convert the laser light scanned by the uniform rotational movement of the rotary polygon mirror 104 into the scan of the uniform linear movement. It has a function.

The laser light emitted from the semiconductor laser 101 is scanned by the rotary polygon mirror 104 through the collimator lens 102 and the cylindrical lens 103, and the first f
The light passes through the theta lens 105 and the second f theta lens 106, is reflected by the folding mirror 107, and is imaged on a drum surface (not shown). Here, both f theta lenses 105,
The optical characteristics of 106 change due to expansion and contraction due to environmental changes such as temperature and humidity. In particular, when the f theta lens is made of plastic, the amount of expansion and contraction is large, which causes a problem.

For example, when it changes symmetrically in the longitudinal direction with respect to the optical axis, no major problem occurs in the optical function, but if it expands or contracts greatly on one side, the problem of eccentricity occurs and the optical performance deteriorates significantly. Cause.

Therefore, it is necessary to devise a method of attaching the f theta lens. Hereinafter, a method of mounting the second f theta lens 106 will be described in particular, but the same applies to the first f theta lens.

FIGS. 9 and 20 are views showing a mounting method when a conventional f theta lens is incorporated in an optical box.

As shown in FIG. 9, the longitudinal direction of the second f theta lens 106 is fixed by the positioning pin 6, and the optical axis direction is fixed by the positioning pin 7. Also, as shown in FIG.
The positioning pins 6 and 7 are integrally formed on the inner wall of the optical box 110, and the second f theta lens 106 is abutted on the positioning pins 6 and 7, whereby the positions of the lenses in the longitudinal direction and the optical axis direction are regulated. It is supposed to be done.

However, as shown in FIG. 9, even if the positioning pin 6 is abutted against the end face 8 in the longitudinal direction of the second f theta lens 106 to regulate the position in the longitudinal direction, the surrounding environment such as temperature and humidity is affected. Due to the change, the second f theta lens 10
6 expands and contracts with the end face 8 as a reference position, which causes a problem of deviation (eccentricity) of the optical axis 9. Therefore, as shown in FIG. 15, in the conventional case, the protrusion 2 is formed near the center in the longitudinal direction.
21 is provided on the side surface of the projecting portion 2, and a flat surface portion 3 having a surface perpendicular to the longitudinal direction, which serves as a reference for the dimension in the longitudinal direction, is provided, and as shown in FIG.
When the flat part 3 is assembled into the optical box, the projection 2 is positioned so that the flat part 3 is sandwiched by the two positioning pins 6, and the positioning pins 6 come into contact with the flat part 3. Is regulated so that even if the f theta lens expands or contracts, the expansion or contraction occurs substantially symmetrically with respect to the optical axis 9 in the longitudinal direction.

[0012]

Problem to be Solved by the Invention [First Problem] FIG.
In the conventional example shown in FIG. 5 and FIG. 21, both surfaces of the flat surface portion 3 provided on the second f theta lens 106 are formed parallel to the mold releasing direction from the mold at the time of lens molding. The protrusion 2 is deformed by rubbing the portion 3 with the mold surface,
There is a drawback in that the deformation at the time of release extends to the vicinity of the root portion between the projection 2 and the lens surface and deteriorates the shape of the lens surface.

The reason for this will be described in detail with reference to FIGS. 11 and 12. The mold 11 for molding the f theta lens 106 shown in FIG. 8 includes a fixed side mounting plate 12 and a fixed side mold plate 1.
3, movable side mold plate 14, pressure receiving plate 15, spacer block 16, movable side mounting plate 17, ejector plate 18, 1
9, a spool 20, a runner 21, and an ejector pin 22.

After the mold 11 is attached to a molding machine (not shown) and the temperature is adjusted to a predetermined temperature, the molten plastic is
It passes through the spool 20, the runner 21, and the gate 5 into the cavity in which the transfer surface of the lens 106 is formed, and is filled in the cavity. After that, the mold is cooled, and as shown in FIG. 12, the fixed side mold plate 13 and the movable side mold plate 14 are
Open the mold 11 between the ejector plates 18, 19
Of the molded product (spool 20, runner 2) through the ejector pin 22
1, gate 5, lens 106) is projected from the cavity surface of the mold.

Here, when the molded product is ejected from the die 11, the plane portion 3 of the protrusion 2 rubs against the plane portion 23 of the die 11 which forms the transfer surface of the plane portion 3. Similarly, the lens end surface 8 also rubs against the transfer surface 24 forming the lens end surface 8, but since the lens end surface 8 is not an abutting surface when the lens 106 is incorporated in the optical box, the lens end surface 8 is perpendicular to the longitudinal direction. The lens end surface 8 may be formed with a certain degree of gradient at the time of die cutting. However, as shown in FIG. 8, since the flat surface portion 3 is brought into contact with the positioning pin 6 for positioning in the longitudinal direction, it must be a surface vertical to the longitudinal direction, that is, a surface parallel to the die cutting direction. When the part 2 is released, the flat surface part 3 rubs against the flat surface part 23 of the mold 11 to deform the projection part 2 due to the mold release resistance, and the effect of the release deformation is on the lens surface near the projection part 2. If it reaches the range, there is a drawback that the shape of the lens surface is deteriorated.

The present invention has been made in view of the above problems. A first object of the present invention is to provide an optical element excellent in optical performance by providing a shape portion for preventing deterioration of the shape of the lens surface at the time of mold release so that the lens can be surely positioned. Is to provide.

A second object of the present invention is to provide a molding die having a transfer part corresponding to the shape part in an optical element having a shape part for preventing the deterioration of the lens surface shape at the time of release. .

A third object of the present invention is to provide an optical element having a highly accurate lens surface shape.

A fourth object of the present invention is to provide an optical device for easily positioning a long optical element and constituting a highly accurate light beam scanning optical system.

A fifth object of the present invention is to provide an optical device for easily positioning a long optical element and constituting a highly accurate image reading optical system.

On the other hand, there is an advantage that an optical element having a special lens shape such as an aspherical shape can be manufactured with high productivity and at low cost, but on the other hand, there are the following drawbacks when molding with a mold. That is, for example, as shown in FIG.
The molten plastic is poured from the gate 5 into the mold 5, and pressure is applied for a certain period of time after filling the molten plastic into the mold 11 so as not to cause defects such as sink marks having a depressed surface. Is rapidly cooled and its viscosity rises while flowing into the mold and after filling into the cavity, so the pressure applied to the mold is sufficiently transmitted to the plastic near the gate 5, but from the gate. A pressure drop occurs at a distant portion, resulting in insufficient transfer of the cavity surface. Therefore, in the part far from the gate, the transferability of the cavity surface is poor, that is, the shape accuracy of the optical functional surface of the molded product is poor,
The problem of deterioration of optical performance occurs.

Therefore, in order to improve the transferability of the portion far from the gate, an excessive pressure is applied from the gate 5,
Increase the filling speed of the molten plastic into the cavity,
Even in the portion far from the gate 5, it is necessary to allow sufficient pressure to be transmitted before the viscosity of the plastic increases.

However, although the above-mentioned countermeasure eliminates the problem in the portion far from the gate, for example, the internal pressure near the gate becomes too high, and the vicinity of the gate of the molded product expands after being taken out from the mold and the lens The surface shape is deteriorated and the internal distortion as observed in birefringence is caused, which deteriorates the optical performance.

Further, if the filling speed of the cavity is increased, a defective appearance called weld or silver occurs near the gate. This kind of defect occurs even during normal molding, but is particularly remarkable when molding a long lens.

In molding an optical lens, it is generally necessary to transfer the shape of the cavity surface with higher accuracy than in the case of a plastic molded product other than the lens. Therefore, molding is performed at a higher pressure than in normal molding. Therefore, even if it is not near the gate, when the molded product is ejected from the mold, it rubs against the transfer surface of the mold, and the peripheral surface and both ends of the molded product deteriorate in surface shape and are observed as birefringence. Internal distortion is more likely to occur, but in long lenses, the length from one end to the other end in the longitudinal direction is long, so when protruding from the mold, the transfer surface rubs and bending stress is applied to the lens. A large impact.

Since the above-mentioned problems occur, when the lens is molded, it is possible to suppress the problems by molding in advance in a portion where a highly accurate optical function surface is required, with a dimension larger than a required dimension.

For example, in the case of a long lens, in order to increase the dimension in the longitudinal direction against the peripheral portion and both end portions of the lens, deterioration of the shape of the lens surface, occurrence of internal distortion, and appearance failure, In addition, the cavity length is lengthened to form a lens having an outer shape larger in the longitudinal direction than the minimum required optical dimension.

However, in reality, it is often the case that the lens shape cannot be enlarged because it is necessary to dispose another component near the lens or a portion corresponding to the optical path. . [Second Problem] FIG. 22 is a perspective view of an optical device used in a scanning optical system of a conventional laser printer or digital copying machine. FIG. 23 is a plan view of FIG. Incidentally, FIG.
The same components as 0 are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIGS. 22 and 23, the laser light emitted from the semiconductor laser 101 is scanned by the rotary polygon mirror 104, passes through the first f-theta lens 105 and the second f-theta lens 106, and the drum 120 surface. Imaged above. The emission of the semiconductor laser 101 is controlled by the controller 133 via the laser driver 131. The rotation of the rotary polygon mirror 104 is controlled by the controller 133 via the scanner drive circuit 132. The light emitted at one end of the light scanning range is captured by the photoelectric sensor 108 via the reflection mirror 109, and is input to the controller 133 as a scanning cycle signal via the horizontal cycle circuit 135. A video signal output from a video device (not shown) is used as a video signal in the video interface circuit 13
4 is input to the controller 133.

Here, the end surface 2 of the f theta lens 105 is located at a position close to the luminous flux of the laser light 112 emitted from the semiconductor laser 101. On the other hand, since the laser beam other than the laser beam scanned by the rotary polygon mirror 104 does not pass through the end face 3 in the immediate vicinity, the end face 3 is formed at a position sufficiently distant from the outermost off-axis light beam 113. Since it can be done, the luminous flux 113
Can pass through the f theta lens 105 without any problem in optical performance.

Since the end surface 2 cannot be sufficiently distanced from the outermost off-axis light beam 114 on the opposite side, the light beam 114 will pass through a portion where the lens surface shape is deteriorated or internal distortion observed in birefringence is present. , It will affect the optical performance.

The present invention has been made in view of the above problems, and a sixth object thereof is to provide a method of molding an optical element capable of improving the optical performance of the peripheral portion and the end portion of a lens.

A seventh object of the present invention is to provide an optical element and an optical device having high optical performance at the peripheral portion and the end portion of the lens.

[0034]

In order to solve the above problems and achieve the object, the optical element of the present invention has the following constitution. That is, in an optical element in which a shaped portion for restricting positional displacement in the longitudinal direction of the optical element is provided in a predetermined portion of a long optical element, the optical element is molded only on one side of the shaped portion. A surface portion parallel to the direction of releasing from is provided.

Further, preferably, on the other side surface of the shaped portion, a surface portion inclined in a direction in which the mold is easily released is provided.

Further, preferably, the optical element is an f theta lens.

Further, preferably, the shape portion is formed in a convex shape at the predetermined portion.

Further, preferably, the shape portion is formed in a concave shape in the predetermined portion.

Further, the molding die of the present invention has the following constitution. That is, in a molding die of an optical element in which a shape part for regulating the displacement of the optical element in the longitudinal direction is provided in a predetermined portion of a long optical element, only one side surface of a transfer part corresponding to the shape part is formed. Further, a transfer surface parallel to the direction of releasing the optical element from the mold was provided.

Further, preferably, a transfer surface is provided on the other side surface of the transfer portion, the transfer surface being inclined in a direction from which the mold can be easily released.

Further, preferably, the optical element is an f theta lens.

Further, preferably, the transfer portion is formed in a concave shape corresponding to the shape portion.

Further, preferably, the transfer portion is formed in a convex shape corresponding to the shape portion.

The optical device of the present invention has the optical element according to any one of claims 1 to 5, and is provided with a member for contacting one side surface of the shaped portion to position the optical element. And has a scanning optical system for scanning a predetermined light beam.

Further, an optical device of the present invention has an optical element according to any one of claims 1 to 5, and a member for contacting one side surface of the shaped portion to position the optical element. And has a reading optical system for reading a predetermined image.

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a diagram showing a long lens according to an embodiment of the present invention.

As shown in FIG. 1, the long lens 116 is
The f theta lens is used in a scanning optical system of a laser beam printer or the like, and has a function of converting laser light scanned by the uniform rotational movement of the rotary polygon mirror 104 into scanning of a uniform linear movement. Near the center of the long lens 116 along the longitudinal direction, a projection 116a having a flat surface portion 3 and a sloped portion 116b for restricting the dimensional change due to the positional displacement in the longitudinal direction or the expansion and contraction is provided.

The plane portion 3 is provided on one side surface of the protrusion 116a and positions the long lens 116 in the longitudinal direction. The slope portion 116b is provided on the other side surface of the protrusion 116a,
It is inclined from the mold so that it can be easily released.

That is, when the long lens is released from the mold, only the flat surface portion 3 which is one side surface of the protrusion 116a is formed in parallel with the releasing direction. As shown in FIGS. 13 and 14, when the molded product is released from the mold, the flat surface portion 3 of the protruding portion 116 a is the flat surface portion 23 of the mold 11.
When the mold is slightly released from the mold due to the slope of the sloped portion 116b, the sloped part 116b can be released from the mold without rubbing.

Further, since the molded product can be released from the flat portion 3 of the projection 116a without a large release resistance, the projection 116a is deformed and the influence of the release deformation is influenced by the projection 116.
It does not extend to the lens surface in the vicinity of a or deteriorate the lens surface shape.

An optical box 1 having a long lens shown in FIG.
In the case of assembling it in 10, as shown in FIG. 6, the planar portion 3 is brought into contact with the positioning pin 6 in the longitudinal direction to regulate the positional displacement in the longitudinal direction. In this case, in order to surely make contact with the positioning pin 6, it is preferable to urge the elongated lens 116 from the end face 8 to the right side in FIG. 6 by an elastic body such as a spring. It is also an effective method to bond the positioning pin 6 and the flat surface portion 3 in contact with each other.

FIG. 10 is a view showing a state in which the long lens of this embodiment is incorporated in an optical box.

In FIG. 10, an optical device 111 includes a semiconductor laser 101 as a light source and a collimator lens 102.
A cylindrical lens 103, a rotary polygon mirror 104 for scanning a laser beam, a first f theta lens 105,
The second f theta lens 116 and the folding mirror 107 are provided, and the first and second f theta lenses 105 and 116 are provided.
Has a function of converting a laser beam scanned by the rotary polygon mirror 104 in a uniform rotational motion into a uniform linear motion.

The laser light emitted from the semiconductor laser 101 is scanned by the rotary polygon mirror 104, passes through the first and second f-theta lenses 105 and 116, and the folding mirror 107.
And is imaged on a drum surface (not shown). The second f theta lens 116 is incorporated in the optical box 110 while the flat portion 3 is brought into contact with the positioning pin 6 in the longitudinal direction to regulate the positional displacement in the longitudinal direction.

In FIG. 1, the case where the flat surface portion 3 is formed on the gate 5 side of the protrusion 116a has been described, but as shown in FIG. 3, the flat surface portion 3 is formed on the side opposite to the gate 5 side. Is also good. In this case, the optical box is assembled in the state shown in FIG.

2 and 4 show the shapes of the second f theta lens 116 taken along the lines AA 'and BB' in FIGS. 1 and 3, the protrusions 116a are formed on both sides of the lens surface. It is not necessary to form it (see FIG. 16), and as shown in FIGS.
It is sufficient if it is formed only on the side that comes into contact with the positioning pin. In this way, the influence of mold release deformation is reduced.

The plane portion for positioning the second f theta lens in the longitudinal direction is not limited to the projection shape, but may be, for example,
As shown in FIG. 5, the same effect can be obtained when a concave portion is formed in the lower part of the lens and the flat surface portion 3 and the inclined surface portion 116b are formed on the side surface of the concave portion. In the case of the lens of FIG. 5, a convex portion corresponding to the concave portion is provided on the cavity surface of the mold.

Further, the positioning portions which are the projections and the recesses do not have to be near the center of the lens in the longitudinal direction.
It does not matter at any place in the longitudinal direction. However, it can be said that near the center in the longitudinal direction, the contraction of the long lens occurs symmetrically in the substantially central portion, which is desirable in terms of optical performance. [Other Embodiments] FIG. 17 is a view showing a long lens according to another embodiment of the present invention.

In FIG. 17, the elongated lens 115 is an f theta lens used in a scanning optical system used in a laser beam printer or the like, as in the above embodiment.

Reference numeral 104a indicates a reflection point of the rotary polygon mirror, which is a laser beam 1 emitted from the semiconductor laser 101.
The laser beam 114 is reflected by the rotary polygon mirror 104.
To the laser beam 113.

Reference numerals 60 and 61 denote lens surfaces of the first f theta lens 115, and a brim 50 having a rectangular cross section is formed at the end portions of the lens surfaces 60 and 61, and one end surface 30 thereof is formed. . Although the brim 50 is not formed at the other end 31, at the time of lens molding, a mold shown in FIG. 19 is used to form the brim 50 at both ends of the f theta lens 115 shown in FIG. Molded.

FIG. 19 shows the f theta lens 1 of this embodiment.
15 is a mold cross-sectional view for molding 15.

A mold 200 for molding the f theta lens 115 shown in FIG. 19 includes a fixed side mounting plate 212, a fixed side mold plate 213, a movable side mold plate 214, a pressure receiving plate 215, a spacer block 216, and a movable side. Mounting plate 217, ejector plates 218, 219, spool 220, runner 22
1, an ejector pin 222, and a gate 223.

After the mold 11 is attached to a molding machine (not shown) and the temperature is adjusted to a predetermined temperature, the molten plastic is
It passes through the spool 220, the runner 221, and the gate 223, flows into the cavity in which the transfer surface of the lens 115 is formed, and is filled in the cavity. After that, the mold is cooled, and as shown in FIG. 12, the mold 200 is opened between the fixed-side mold plate 213 and the movable-side mold plate 214, and the ejector plates 218 and 219 are moved toward the fixed-side mold plate 213. By making the ejector pin 222 protrude, the molded product is caused to protrude from the cavity surface of the mold via the ejector pin 222.

At the time of molding this lens, the lens 1 is made to contact the tip of the ejector pin 222 shown in FIG.
It is better to form the brim 50 on 15. Further, as described in the section of the problem, the peripheral portion and the end portion of the lens are apt to have a deteriorated surface shape, internal distortion, and poor appearance.
Therefore, the required light beam effective portion (the laser beam 1 in FIG.
It is necessary to make the lens surface larger than the range from 14 to the laser light 113), that is, to make the outer shape of the lens as large as possible in order to form a lens having excellent optical performance. In general, since the lens has shrinkability, the cavity size is made larger than the actual size of the molded product. It is different from enlarging the cavity shape of the mold by the amount of shrinkage of the molding material.

When the lens 115 is incorporated in the scanning optical system with the lens shape shown in FIG.
Since the laser beam 112 impinges on it, it cannot be used in this lens shape.

Therefore, after taking out the lens from the mold, the lens is cut along the one-dot chain line 51 in FIG. 18 to obtain the lens shape shown in FIG. 17 and incorporated in the scanning optical system.
At this time, as the cutting method and the unnecessary portion removing method and means, it is preferable to use a heated sharp one (for example, a hot knife), but the method and means are not particularly limited. Also regarding the timing of cutting, the lens may be cut off within the mold even after it is taken out from the mold.

When the lengthy lens of the present embodiment is examined in detail, in the lens molded by the mold, the optical function surface (mirror surface in the case of a mirror, lens surface in the case of a lens, for example, in FIG. The length of the lens surfaces 60, 61) is the effective light portion (laser light 11) required for optical performance.
It has been found that in order to obtain a lens having excellent optical performance, it is necessary to form one side longer than 4 mm by 4 mm or more, preferably 6 mm or more. However, in the case of cutting after molding, at a distance of 2 mm from the effective ray portion required optically,
If it can be cut, it is possible to obtain a lens having substantially the same optical performance as in the case where the one side is formed longer than 6 mm.

This is because the deterioration of the surface shape generated at the peripheral portion and the end portion of the lens and the internal distortion observed in the birefringence are caused by the stress even though the lens being molded is considerably cooled in the mold. This is caused by the fact that the molded product must be subjected to unreasonable stress when using a heated cutter, etc. It is possible to cut in the vicinity of the light ray effective portion which is required for optical performance, without leaving.

The present invention can be applied to a modified or changed version of the above embodiment without departing from the spirit of the present invention.

The long lens may be made of any material such as plastic, glass, a material containing plastic, a material containing glass, etc. that can be melted and can be molded using a mold.

Although the f-theta lens has been described as an example of the long lens, a cylindrical lens may be used as long as it is a long lens, or a bar lens used in an image reading optical system of a facsimile or the like. May be

In the case of a long lens, the deterioration of the surface shape, the occurrence of internal distortion, and the appearance defect are likely to occur especially at the peripheral portion and the end portion of the lens. Therefore, for example, a cylindrical lens of a scanning optical system (see FIG. 10). , The cylindrical lens is arranged only in front of the rotary polygon mirror, but depending on the configuration, it may be arranged behind the f theta lens and before the folding mirror. In that case, a long lens is used. It is also useful for forming a folding mirror of a scanning optical system, a bar lens of a reading optical system, a folding mirror of a reading optical system, and the like.

Further, in the above-described embodiment, the case where the lens cannot be made long because other rays pass nearby has been described. However, as an example in which the lens cannot be made long or large, other components are However, it is conceivable that the fingers are close to each other or that a finger operation space at the time of assembling must be secured, and the present invention is not limited to the above case.

Further, in the above-described embodiment, the surface shape is deteriorated and the internal distortion is generated in the peripheral portion and the end portion of the lens.
Although description has been made by taking as an example the plastic molding in which defective appearance is likely to occur, the material is not particularly limited as long as the same effect can be obtained by press molding of glass and molding can be performed using a mold.

[0085]

As described above, according to the present invention,
By providing a shape portion that prevents deterioration of the lens surface shape at the time of releasing from the mold, it is possible to reliably position and improve optical performance.

Further, by providing a transfer portion corresponding to a shape portion for preventing the deterioration of the lens surface shape at the time of releasing, a lens having high optical performance can be molded.

Further, it is possible to obtain an f theta lens having a highly accurate lens surface shape.

Further, it is possible to easily position the long optical element and construct a high-precision optical scanning system for light rays.

Further, a long optical element can be easily positioned, and a highly accurate image reading optical system can be constructed.

Moreover, the optical performance of the peripheral portion and the end portion of the lens can be improved, and a highly accurate optical device can be obtained.

[0091]

[Brief description of drawings]

FIG. 1 is a diagram showing a shape of a long lens according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line A-A ′ of FIG.

FIG. 3 is a diagram showing a shape of a long lens according to another embodiment of the present invention.

FIG. 4 is a cross-sectional view taken along the line B-B ′ of FIG.

FIG. 5 is a diagram showing a shape of a long lens of a modified example of the present embodiment.

FIG. 6 is a diagram showing a method of attaching the long lens according to the present embodiment.

FIG. 7 is a diagram showing a method of attaching a long lens according to another embodiment.

FIG. 8 is a diagram showing a conventional method of attaching a long lens.

FIG. 9 is a diagram showing a conventional method of attaching a long lens.

FIG. 10 is a diagram showing an optical device as a scanning optical system in which the long lens of this embodiment is mounted.

FIG. 11 is a view showing a conventional mold for a long lens.

FIG. 12 is a diagram showing a state at the time of releasing the molding die shown in FIG. 11.

FIG. 13 is a view showing a molding die for a long lens of the present embodiment.

FIG. 14 is a diagram showing a state at the time of releasing the molding die shown in FIG.

FIG. 15 is a diagram showing the shape of a conventional long lens.

16 is a cross-sectional view taken along the line C-C ′ of FIG.

FIG. 17 is a diagram showing a shape of a long lens according to another embodiment.

FIG. 18 is a view showing a shape of a long lens of another embodiment before being cut.

FIG. 19 is a view showing a molding die for a long lens according to another embodiment.

FIG. 20 is a diagram showing an optical device used in a conventional scanning optical system.

FIG. 21 is a diagram showing an optical device used in a conventional scanning optical system.

FIG. 22 is a perspective view showing an optical device used in a conventional scanning optical system.

FIG. 23 is a diagram showing an optical device used in a conventional scanning optical system.

[Explanation of symbols]

3 ... Plane 6 longitudinal positioning pin 7 ... Positioning pin in the optical axis direction 8 ... End face 9 ... Optical axis 11,200 ... Mold 101 ... Semiconductor laser 102 ... Collimator lens 103 ... Cylindrical lens 104 ... Rotating polygon mirror 110 ... Optical box 111 ... Optical device 115 ... 1st f theta lens 116 ... Second f-theta lens 116a ... Protrusion 116b ... Slope part

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sou Yokokawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-9-184990 (JP, A) JP-A-9 -90255 (JP, A) JP-A-9-325202 (JP, A) JP-A-4-70619 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02B 26/10

Claims (12)

(57) [Claims] 1. An optical element in which a shaped portion for restricting displacement of the optical element in the longitudinal direction is provided in a predetermined portion of a long optical element, wherein the optical element is provided only on one side surface of the shaped portion. An optical element having a surface portion parallel to the direction of releasing from the molding die. 2. The optical element according to claim 1, wherein the other side surface of the shaped portion is provided with a surface portion inclined in a direction in which the mold is easily released from the mold. 3. The optical element according to claim 1, wherein the optical element is an f theta lens. 4. The optical element according to claim 1, wherein the shaped portion is formed in a convex shape at the predetermined portion. 5. The optical element according to claim 1, wherein the shaped portion is formed in a concave shape in the predetermined portion. 6. A molding die for an optical element, wherein a shape portion for restricting displacement of the optical element in the longitudinal direction is provided at a predetermined portion of a long optical element, wherein a transfer portion corresponding to the shape portion is formed. A molding die characterized in that a transfer surface parallel to the direction of releasing the optical element from the molding die is provided on only one side surface. 7. The molding die according to claim 6, wherein the other side surface of the transfer portion is provided with a transfer surface inclined in a direction in which the mold is easily released from the molding die. 8. The mold according to claim 6, wherein the optical element is an f theta lens. 9. The molding die according to claim 6, wherein the transfer portion is formed in a concave shape corresponding to the shape portion. 10. The transfer part is formed in a convex shape corresponding to the shaped part.
The molding die according to any one of 1. 11. An optical element according to any one of claims 1 to 5, further comprising a member for contacting one side surface of the shaped portion to position the optical element, and An optical device comprising a scanning optical system for scanning. 12. An optical element according to any one of claims 1 to 5, further comprising a member for contacting one side surface of the shaped portion to position the optical element, and displaying a predetermined image. An optical device comprising a reading optical system for reading.