JP2001083306A - Glass lens and its production, truing method for grinding wheel, metal mold for molding optical parts and optical parts by the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass lens formed by using the glass previously performed to a prescribed shape and heating and pressurizing the performed glass and the glass lens which is inexpensive in the production of the metal mold for the same as well as the metal mold which is inexpensive and long in life and a process for producing the same. SOLUTION: This process for production consists in forming projecting parts 3 in the shorter side of the glass lens 1 in the manufacture of the glass lens 1 having a longitudinal direction and the shorter side direction on an optical surface by forming the performed glass 7 to 7f. A spindle 24 for rotating the grinding wheel is rotated at <=500 rpm when a free curved surface is formed on a body 29 to be worked by using the outer periphery of a flat type grinding wheel 23 which is mounted at the spindle 24 for rotating the grinding wheel and of which the outer periphery is formed as a curved surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass lens produced by molding a preformed glass, a mold for molding the glass, and a technique for producing the mold. The present invention relates to a grinding technique for performing high-precision grinding, a truing and dressing technique for a grindstone, and the like.

[0002]

2. Description of the Related Art A lens of an optical system based on optical scanning of a laser beam, such as an electronic copier or a laser printer, usually has fθ
Lenses are used. The fθ lens is manufactured by placing a glass preformed in a predetermined shape into a mold in advance, and sequentially forming the glass through respective steps of heating, melting, and pressing (hereinafter, referred to as a lens). Is used. At this time, it is preferable that the shape of the preform is a simple shape in view of cost. Therefore, the preform is processed with a curvature in the scanning direction as shown in FIG. 1 and has a curvature in the sub-scanning direction. A cylindrical shape which is flat without being attached is common.

[0003] That is, FIG. 14 shows the shape of the preformed glass 51.
The shape 1 is formed so that the surface forming the convex side of the lens has a smaller curvature than the lens, and the surface forming the concave side of the lens has a larger curvature than the lens.

FIGS. 15A and 15B are perspective views of a mold for molding a lens using preformed glass. FIG. 15A is a perspective view of a lower mold for molding the exit surface of the lens. FIG. 15B is a perspective view of an upper mold for molding the entrance surface of the lens.

That is, a convex surface 53 as a molding surface is formed in the upper die 52, and a cavity 55 for accommodating the preformed glass 51 is formed in the lower die 54,
At the bottom of the cavity 55, a concave surface 56 is formed as a molding surface.

The molded lens (not shown) has a free-form surface formed in the scanning direction and the sub-scanning direction when mounted on an optical system and used, and both ends in the scanning direction are filled during press molding. An escape portion is provided so that the surplus surplus glass escapes.

[0007] The free-form surface of the mold is finished by using a flat-shaped whetstone. In addition, as a method of tooling or dressing the working surface of a flat R-attached grinding stone to a highly accurate circular cross section, if a general method is exemplified,
The following are mentioned.

(1) A method in which a diamond point tool is turned to process a protruding contour of a cutting edge of a grinding wheel for curved surface processing into an R shape. In addition, a reshing effect can be obtained by adding free abrasive grains to the composition of the grindstone.

(2) A method in which a rotating hollow cylindrical grindstone is pressed against a grindstone for processing a curved surface to form the working surface of the grindstone for curved surface processing into an R shape (partially spherical surface). (JP-A-7-29974
(3) A method of shaping the working surface of a grinding wheel for curved surface processing into an R shape by electric discharge machining.

(4) The working surface of the grinding wheel for curved surface processing is dressed by electrolytic action.

The fθ lens is manufactured by attaching a preformed glass to the mold using the mold manufactured by the above and press-molding the glass.

[0012]

However, in the above-mentioned glass molded lens, since the glass preformed in a predetermined shape is used, the cost of the preform becomes high, and the cost of the glass lens formed thereby becomes high. Become.

When a preform glass having a rectangular cross section is used in order to reduce the cost of the preform, as shown in FIGS. 16 (a) and 16 (b), as shown in FIGS. In the lens forming process starting from a state in which the upper mold 52a is separated from the lower mold 54a as shown in ()), there is a space between the preform glass 51a having a rectangular cross section and the bottom surface of the cavity 55a of the lower mold 54a. 16 (b), when the upper mold 52a is lowered and molded, the wound air remains in the cavity 55a and a predetermined molded shape cannot be obtained. .

In the case of molding using preformed glass 51b having a circular cross section as shown in FIG.
When the preformed glass 51b and the lower mold 54b come into contact with each other, the lower mold 52b descends and press molding starts.
4b, two points A ₁ and A ₂ at both ends in the sub-scanning direction at the center of the (emission surface) scanning direction (the preformed glass 51b).
, The load is concentrated on these two points, and a high pressure is applied near these two points. Therefore, due to the concentrated load, the coating of the surface of the lower mold 54b is eventually peeled off, and the metal part of the lower mold 54b and the preformed glass 51b are melted at that portion, thereby causing a product (lens) defect. There is fear. If the preformed glass 51b has a curvature different from the main scanning direction in the sub-scanning direction, the preformed glass
The number of steps required for manufacturing b increases and the cost increases, which is not preferable.

In the case where tooling and dressing are performed on the working surface of the above-mentioned flat-shaped grinding wheel with a highly accurate circular cross section.

In the case of the above (1), since the dressing action does not occur unless free abrasive grains are added, the truing efficiency is poor. Therefore, the efficiency of truing and dressing is not good.

In the case of the above (2), the working surface of the grinding wheel for curved surface processing cannot be formed into an R shape having a radius smaller than the radius of the grinding wheel.

In the above cases (3) and (4),
Applicable curved surface processing whetstones are limited to metal bond whetstones. Further, in any of the methods, the working surface of the flat R-shaped resinoid bonded grindstone cannot be efficiently and trued into an R shape having a desired radius.

The present invention has been made on the basis of the above-described circumstances, and uses preformed glass in a predetermined shape, and heats the preformed glass.
To provide an inexpensive glass lens, an inexpensive and long-lasting mold for molding it, a method of manufacturing the same, and a grinding wheel shaping technique in the production of a glass lens to be molded by applying pressure. It is an object.

[0020]

According to a first aspect of the present invention, there is provided a glass lens having an optical surface having a longitudinal direction and a lateral direction, and a projection formed in the lateral direction. It is a glass lens characterized in that it is formed so that the area in each cross section in each direction is substantially equal.

According to the second aspect of the present invention,
The projection is a glass lens having a free surface.

According to the third aspect of the present invention,
The glass lens described above is an fθ lens.

Further, according to the means of the present invention,
Holding the preformed glass in a mold, in a method of manufacturing a glass lens to form a predetermined shape by pressing in a heated state, holding the preformed glass,
Thereafter, pressure is applied by two lines or surfaces outside the optical regions at both ends of the lens.

According to the fifth aspect of the present invention,
In a truing method for a grindstone performed by rotating and swinging a dresser block disposed at a position facing the outer periphery of the grindstone,
A truing method for a grindstone, characterized in that the grinding wheel is rotated at 0 rpm or less and cut into the dresser block at a relatively constant speed in a direction substantially parallel to the rotation axis of the dresser block.

According to the means of the invention of claim 6,
In a truing method of a grindstone performed by bringing a dresser block into contact with a grindstone to be rotated, the dresser block is formed so that the surface of the dresser block that is exposed by dressing the grindstone by the contact does not contact the grindstone. This is a truing method of a grindstone characterized by relatively feeding.

According to the means of the invention of claim 7,
The dressing block is a truing method for a grinding wheel according to any one of the above, characterized by using any one of a stick-shaped block of alumina or silicon carbide abrasive grains, a stick-shaped block of mild steel or a metal bond diamond block. .

According to the means of the invention of claim 8,
An optical component molding die characterized by being ground using a grindstone shaped by the truing method of a grindstone described above.

According to the means of the ninth aspect,
An optical component formed using the lens molding die described above.

[0029]

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

FIG. 1A is a perspective view showing the lens shape of the glass lens of the present invention as seen through the inside, and FIGS. 1B and 1D are cross-sectional views of both ends in the longitudinal direction. Is a sectional view of a central portion in the longitudinal direction.

The effective area 2 of the glass lens 1 which performs an optical function as a lens is shown in FIGS. 1 (b) to 1 (d).
In each cross-sectional view of FIG. Other areas including the projections 3 formed at both ends in the lateral direction of the lens do not perform the optical function as a lens. However, when the glass lens 1 is incorporated into an optical system (not shown), It functions as a general positioning part and a mounting part.

The cross-sectional area of the projection 3 formed in the short direction of the glass lens 1 is, as shown in FIGS. 1B to 1D, the cross-sectional area of the effective territory of the glass lens 1. The size of the cross-sectional area of the protrusion 3 is set so as to decrease as the size increases. That is, the glass lens 1
The cross-sectional area of each cross-section in the longitudinal direction is set by adjusting the size of the protrusion 3 so that the cross-sectional areas are equal.
This makes it easy for extra glass to escape to the protrusions 3 when a preform of the same amount as a relatively large area is injected into a portion having a relatively small area with the effective region. . In addition, by forming the protrusion 3 at a relatively large portion to be small, it is possible to prevent the other portion from being unfilled.

Next, a preform and a mold used for molding the above-described glass lens 1 and a molding method thereof will be described.

FIGS. 2A and 2B are schematic views of a glass lens forming process. FIG.
(B) shows the state during molding.

That is, first, in a state where the upper mold 4 and the lower mold 5 are separated, the glass 7 (BK7) preformed in a columnar shape at a predetermined position in the cavity 6 of the lower mold 5 is set in the horizontal direction. In this state, both ends in the longitudinal direction of the preformed glass 7 are supported by the support portions of the cavity 6, and a space is formed between the central portion in the longitudinal direction and the bottom of the cavity 6. The preformed glass 7 in the cavity 6 is also heated to a predetermined temperature.

Next, as shown in FIG. 2 (b), the upper mold 4 is used for the preformed glass 7 in the cavity 6 of the lower mold 5.
And descends while pressing it. By this operation, the preformed glass 7 is first deformed in the pressing direction of the upper mold 4, and thereafter, the preformed glass 7 is deformed.
Is deformed in the short side direction and the long side direction, and is filled in the space in the cavity 6 of the lower mold 5 to be formed into a predetermined shape.

In the above case, the preformed glass 7 has a circular cross section, but the same effect can be obtained by using an oval or trapezoidal cross section.

The same effect can be obtained even if the cross-sectional shape of the preformed glass 7 is made rectangular and one side of the cross section is sufficiently smaller than the width of the lens.

The material of the preformed glass 7 is not limited to BK7, but a glass material for lenses such as SF10 can be used.

The cross-sectional area in each section in the longitudinal direction of the lens is not necessarily the same in each part. For example, as shown in FIGS. The same effect can be obtained with a glass lens 1a having a structure in which the sum of the optically effective area 2 and the other area is substantially equal. FIG. 3A is a perspective view of the inside of the glass lens, showing the lens shape.
(B) is a cross-sectional view of each end portion in the longitudinal direction, and (c) is a cross-sectional view of a central portion in the longitudinal direction.

Next, a method of supporting the preformed glass 7 inside the cavity 6 of the lower mold 5 by the above-described mold will be described.

FIG. 4A is a front sectional view of the support portion in the cavity, and FIG. 4B is a sectional view taken along the line BB. FIG. 4C is a perspective view of a nest forming a support portion.

That is, in a state where the upper mold 4a and the lower mold 5a are separated from each other, prior to setting the preformed glass 7a inside the cavity 6a of the lower mold 5a, the preformed glass 7a of the lower mold 5a is removed. The nest 8a is inserted at a position where both ends in the longitudinal direction are supported. This allows
Before the press by the upper mold 4 is started, the preformed glass 7a and the nest 8a are in contact with each other and are supported by the nest 8a. The preformed glass 7a and the nest 8a are drawn by a line (cross section taken along the line BB in FIG. 4).
(One side of the lower part). On the other hand, the insert 8a is in surface contact with the lower mold 5a. Therefore, the upper mold 4a
, The surface of the lower mold 5a comes into surface contact, the pressure can be reduced, and the coating (not shown) formed on the surface of the lower mold 5a can be suppressed from peeling off.

As the molding progresses due to the lowering of the upper mold 4a, the preformed glass 7a comes into contact with the central wall surface of the lower mold 5a. Since the pressure applied to the local portion is reduced, damage to the coating surface or the like hardly occurs.

FIGS. 5A and 5B show the above-mentioned application examples. FIG. 5A is a front cross-sectional view of the support portion in the cavity, and FIG. 5B is a cross-sectional view taken along the line CC. FIG. 5C is a perspective view of a nest forming a support portion.

The point different from the above-mentioned supporting method is the structure of the nest 8b. The other parts are the same as in the above-described case, and a description thereof will not be repeated (the reference numeral “a” in FIG. 4 is replaced by “b”). The nest 8b has a structure in which a supporting portion is formed of a two-step curved surface, and the preformed glass 7b is supported by a depression at the intersection of the two curved surfaces. Therefore, when the preformed glass 7b before press molding is set in the lower mold 5b, the position of the preform can be easily set and fixed at a predetermined position.

FIGS. 6 (a) and 6 (b) correspond to FIG.
FIG. 6A is a modification of the application example shown in FIGS.
FIG. 6A is a front sectional view of a support portion in the cavity, and FIG.
(B) is a perspective view of the nest forming the support part. In this case, the support portions of the nest 8c are provided at both ends, and portions other than both ends are made spaces. Thereby, when the width of the nest 8c in the sub-scanning direction is formed to be the same as the width of the mold, the air between the mold and the preformed glass 7c cannot escape and the preformed glass 7c remains unformed. Even if filling occurs, it can be prevented. It is to be noted that a structure may be employed in which slits (not shown) are provided at appropriate intervals without providing spaces except for both ends.

Although the above-mentioned inserts 8a, 8b, 8c all use an arc-shaped curved surface for the support portion, FIG.
As shown in (a) and (b), nests 8d and 8e of a combination of planes formed by straight lines may be used. In the case of the nest 8d shown in FIG. 7A, each plane is rectangular, but in the case of the nest 8e shown in FIG. 7B, each plane has a trapezoidal shape because it is tapered. . However, in any case, it is preferable that the corners where the planes are in contact with each other be rounded or machined on a spherical surface.

Also, as shown in the sectional view of FIG.
May be formed. This is to make the lower mold 5c thicker than the optical surface in the sub-scanning direction, make it flat in the sub-scanning direction, and easily join it to the free-form surface in the main-scanning direction. It is continuous.
When placing the preformed glass 7f, the load can be reduced by contacting the part (D). (D)
Since the portion is not an optical surface, it is not necessary to perform a high-precision finishing process.

According to each supporting method of the present invention as described above, the large pressure (load) generated by the local contact between the mold and the preformed glass in the initial stage of press molding changes the contact state. To reduce pressure,
The peeling of the coating formed on the mold surface can be suppressed, and the life of the mold can be improved.

Next, a method of forming the above-described mold into a free-form surface shape according to the present invention will be described.

FIG. 9 is a schematic view showing the configuration of a processing apparatus of the present invention for forming a grindstone surface into a free-form surface.

A spindle 22 for rotating a grindstone on which a grindstone 23 is mounted is provided on a column 22 erected on an X-axis table 21 movable in the X-axis direction. The grindstone rotating spindle 24 is formed such that a rotating part on which the grindstone 23 is mounted is movable in the Y-axis direction. A dressing unit 26 is provided on a Z-axis table 25 on one side of the grinding wheel rotating spindle 24 in the Z-axis direction. A work holder (not shown) for mounting and fixing the work 29 is provided on the other side of the grinding wheel rotating spindle 24 in the Z-axis direction.

In the dressing unit 26, a dresser block 28 is fixed to the open side of a shank 27 having a concave cross section that performs a reciprocating revolving motion along the C axis. The dresser block 28 has a rectangular parallelepiped shape and one side of the cross section is about 10 mm.

The grindstone rotating spindle 24 is 500
At a rotational speed of not more than rpm, the workpiece 29 has a torque sufficient to perform predetermined grinding at the rotational speed. The grindstone 23 is a resinoid diamond grindstone or a metal bond grindstone, has a diameter of φ80 mm, a thickness of 8 mm, and R formed on the outer peripheral portion is 4 mm.

FIG. 10 is a schematic view showing an example of a free-form surface processing method. When free-form surface machining is performed, the grindstone rotating spindle 24 rotates at a predetermined position on the Y-axis, and the flat R grinding wheel 23 attached to the tip of the grindstone rotating spindle 24 also rotates integrally. In this state, the workpiece 29 mounted and fixed on the workpiece holding table (not shown) moves toward the grindstone 23 by a predetermined amount in the Z-axis direction. The grindstone rotating spindle 24 moves in the X-axis direction and the Y-axis direction to the processing start position of the workpiece 29. The workpiece holder moves in the direction of the grindstone 23 in the Z-axis direction, and comes into contact with the grindstone 23 to start grinding. The movement of the spindle 24 for grinding wheel rotation during this processing is controlled in the X-axis direction and the Y-axis direction by a control unit (not shown) according to the free-form surface of the workpiece 29. The trajectory of the grinding wheel 23 feed by machining is indicated by arrows a1, a2,
a3 ... With these operations, the contour accuracy of the R shape of the working surface of the flat R-shaped grindstone 23 is accurately transferred to the processing surface of the workpiece 29. Note that the workpiece 29 is the whetstone 2
Other than 3 may be used, for example, a glass lens or the like.

When the cross-sectional shape of the curved surface of the workpiece 29 is to be machined with high precision, the contour accuracy of the R shape of the working surface of the grindstone 23 must be higher than the contour accuracy required by the curved surface of the workpiece 29. It is necessary to shape by truing.

Next, the truing of the grindstone 23 will be described. FIG. 11 is a schematic view of the tooling of the grindstone 23, and FIGS. 12A to 12D are explanatory diagrams of the operation at the time of tooling of the grindstone 23.

A dresser block 28 fixed to a shank 27 provided in the dressing unit 26
Is a rectangular parallelepiped truer and dresser with a grinding wheel 2
3 is attached to a shank 27 provided at a position deviated from the central axis (center of rotation) of the C axis so as to rotate around the C axis at the radius of curvature of the R shape of the working surface of No. 3. The reciprocating operation is performed at a constant angle (for example, in a range of ± 40 degrees). In this state, X is applied between the dresser block 28 and the grinding wheel 23 while the grinding wheel 23 is rotated at a low speed of 500 rpm or less.
The dresser block 28 is ground by moving the Z-axis at a constant speed in one direction with a constant cut in the axial direction, and the cross section of the working surface of the grindstone 23 is shaped into a desired R dimension.

FIG. 12A shows a state in which the lower surface of the grindstone 23 is truing and dressing by the dresser block 28, and the dresser block 28 is inclined at a predetermined angle from below with respect to the rotating grindstone 23. The dresser block 28 is moved from the front end side to the rear end side so that truing and dressing are not performed at the same location of the dresser block 28.

Then, along the curved surface of the grindstone 23, FIG.
As shown in FIG. 12B, from the center of the grindstone 23, FIG.
The process is continuously advanced to the upper end of the grindstone 23 as shown in FIG. After the processing has progressed to the upper end of the grindstone 23, the processing proceeds in the reverse order toward the center of the grindstone 23 as shown in FIG. Hereinafter, truing and dressing are repeated as many times as necessary.

The dresser block 28, which is a truer and dresser, has a high truing and dressing effect by processing, for example, a stick-shaped block of alumina or silicon carbide abrasive grains (vitrified grinding stone 23) or the like. Thereby, truing and dressing of the resinoid bond grindstone can be performed with high efficiency.

In the above case, the dresser block 28
By simultaneously performing the reciprocating operation and the one-way constant speed movement of the grindstone 23, a new surface of the dresser block 28 is always machined, so that the truing and dressing operations can be controlled to be constant (the cutting depth × feed speed can be kept constant). ).
Thereby, the contour of the cross section of the working surface of the grindstone 23 can be shaped with high precision.

FIG. 13A shows a mesh size # 120.
11 is a graph showing the result of truing a 0 resinoid diamond grinding stone 23 using a vitrified stick of # 600 silicon carbide abrasive grains as a truer and dresser. FIG. 13B shows that the number of times of touring is four.
It is the graph which expanded the 7th time from the time.

That is, the grinding stone 2
The contour accuracy (range of ± 20 degrees) of the R shape of the working surface of No. 3 is
It is shaped from 26 μm to 0.25 μm.

The state of the working surface of the grindstone is a state in which the dressing has been completed because a vitrified stick of silicon carbide abrasive grains having excellent dressing properties is used for the truer and dresser. In this manner, truing and dressing of the resinoid bond grindstone can be performed with high accuracy in a short time.

The target grindstones include resinoid bond diamond grindstone, resinoid bond CBN grindstone, metal bond diamond grindstone, metal bond CB
All N grinding stones are effective.

As described above, according to the present invention, the load at the initial stage of contact between the lower mold and the preformed glass has conventionally been concentrated at two points on the optical surface. By doing so, the concentration of the load can be reduced and the life of the mold can be improved. Further, since the nest is not used as an optical surface, it is not necessary to manufacture the nest with high precision. Even if the nest coating is peeled off, if only the nest is replaced, high-precision molding can be continued.

When the preformed glass is installed in the longitudinal direction of the lens, a nest that comes into contact with the mold is provided, and the protruding portion is a free surface, so that the volume of the glass material is strictly controlled. There is no need, the cost of the material is low, and the glass lens can be provided at low cost.

Since there is no need for post-processing after molding,
A high quality glass lens can be provided without causing any scratch on the lens surface.

[0071]

According to the present invention, high-precision molding can be performed without entrapping air in a mold at the time of molding a glass lens. Therefore, a low-cost glass lens can be provided.

Further, since the nest is used at the contact portion of the mold, the mold is prevented from being damaged, and a long-life mold can be obtained.

Further, a highly accurate free-form surface grinding method can be obtained, and the truing and dressing of the grindstone can be performed with high accuracy in a short time.

[Brief description of the drawings]

FIG. 1A is a perspective view of the inside of a glass lens of the present invention showing the lens shape thereof, FIGS. 1B and 1D are cross-sectional views of both ends in the longitudinal direction, and FIG. Sectional drawing of the center part of a direction.

FIGS. 2A and 2B are schematic views of a glass lens forming process, wherein FIG. 2A is before forming and FIG. 2B is during forming.

FIG. 3A is a perspective view of a lens of the present invention, and FIGS. 3B and 3C are cross-sectional views thereof.

4A is a front cross-sectional view of a support portion in a cavity according to the present invention, FIG. 4B is a cross-sectional view taken along the line BB, and FIG. 4C is a perspective view of a nest forming the support portion.

5 (a) is a front sectional view of a support portion in a cavity of the present invention, FIG. 5 (b) is a cross-sectional view taken along the line CC, and FIG. 5 (c) is a perspective view of a nest forming the support portion.

6 (a) is a front sectional view of a support portion in a cavity according to the present invention, and FIG. 6 (b) is a perspective view of a nest forming the support portion.

FIGS. 7A and 7B are perspective views showing a modified example of the nest of the present invention.

FIG. 8 is a sectional view of a lower mold of the present invention.

FIG. 9 is a schematic view of a processing apparatus of the present invention.

FIG. 10 is a schematic diagram of processing of a free-form surface.

FIG. 11 is a schematic view showing a truing state.

FIGS. 12A to 12D are explanatory diagrams showing a truing process.

13 (a) is a graph of a truing result according to the present invention, and (b) is a partially enlarged graph of the graph of (a).

FIG. 14 is a perspective view of preformed glass.

15A is a schematic perspective view of a conventional lower mold, and FIG. 15B is a schematic perspective view of a conventional upper mold.

FIG. 16A is a schematic side view of a conventional mold before molding.
(B) A schematic side view of a conventional mold during molding.

FIG. 17 is a schematic side view of a conventional mold before molding.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Glass lens, 3 ... Projection part, 4-4b ... Upper mold, 5
5b: lower mold, 7-7f: glass, 8a-8e: nest,
23 ... whetstone, 28 ... dresser block

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kei Amano 33th Shin Isogocho, Isogo-ku, Yokohama-shi, Kanagawa F-term in Toshiba Production Technology Center Co., Ltd. 3C047 CC03

Claims (9)

[Claims] 1. A glass lens having an optical surface having a longitudinal direction and a lateral direction and a projection formed in the lateral direction, the glass lens being formed so that the area in each section in the longitudinal direction is substantially equal. A glass lens characterized in that: 2. The glass lens according to claim 1, wherein the projection has a free surface. 3. The glass lens according to claim 1, wherein the glass lens is an fθ lens. 4. A method of manufacturing a glass lens in which a preformed glass is held in a mold and pressed in a heated state to form a predetermined shape, wherein the preformed glass is held and then pressed. Is performed using two lines or surfaces outside the optical regions at both ends of the lens. 5. A truing method of a grindstone performed by rotating and swinging a dresser block disposed at a position facing the outer periphery of the grindstone with respect to the grindstone, wherein the grindstone is rotated at 500 rpm or less, and A truing method for a grindstone, characterized in that the dresser block is cut into the dresser block at a substantially constant speed in a direction substantially parallel to a rotation axis of the dresser block. 6. A truing method of a grindstone performed by bringing a dresser block into contact with a rotating grindstone, wherein the surface of the dresser block exposed by dressing the grindstone by the contact does not contact the grindstone. Wherein the dresser block is relatively fed to the grinding wheel. 7. The dresser block according to claim 5, wherein one of a stick-shaped block of alumina or silicon carbide abrasive grains, a stick-shaped block of mild steel, and a metal-bonded diamond block is used.
Or the truing method of a grindstone according to any one of 6. 8. A mold for molding optical parts, characterized by being ground using a grindstone shaped by the truing method of a grindstone according to claim 5. Description: 9. An optical component formed by using the lens molding die according to claim 8. Description: