JPH04204409A - Optical device and plastic lens and forming mold - Google Patents

Abstract

PURPOSE:To eliminate the influence of the nonuniform thicknesses of molded lenses at the time of holding the lenses in a lens barrel when such thicknesses arise by providing projecting parts or recessed parts in the edge parts of the plastic lenses and holding the projecting parts or the recessed parts. CONSTITUTION:The projecting parts 41a to 43a, 41b to 43b or the recessed parts are provided at >=4 points on both surfaces of the edge parts of the lenses 1. The projecting parts 41a to 43a, 41b to 43b or the recessed parts are produced with the good accuracy in the length thereof. The projecting parts 41a to 43a, 41b to 43b or the recessed parts of the lenses 1 are retained by stoppers 6a of the lens barrel 8 or spacing rings 9 at the time of holding the lens 1 to the lens barrel 8. The lenses 1 are, therefore, installed with the accurate inter- lens distances. In addition, the force to retain the lenses 1 in order to hold the lenses is uniformized over the entire circumference of the lenses 1. The fluctuations in the thicknesses of the edge parts of the plastic lenses produced by the molding are prevented from being influenced in this way.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an optical device in which a plastic lens molded by injection molding or the like is held in a lens barrel. The present invention relates to an optical device having a lens and a holding structure that are not affected by variations.

[Prior art] Conventionally, lens barrels, spacing rings, etc. for fixing lenses were disclosed in Japanese Patent Application Laid-Open No. 57-
It has the structure described in Publication No. 138606 etc.
Assuming that the lens is symmetrical about the central axis (optical axis),
It was designed.

In addition, for injection molding molds for multiple high-precision parts such as plastic lenses, molten resin is distributed from the center of the mold to each lens cavity, as described in Japanese Patent Application Laid-open No. 55-25973, and side gates are used to The structure is such that each cavity is filled.

In addition, the conventional method of holding a lens is to press the edge of the lens against a part of the stopper of the lens barrel, insert a one-space ring, press it with the holding part of the spacer ring, set alternate layers between the lenses, and use screws, etc. The lens was fixed to form an optical system.

Problems to be Solved by the Invention] The above conventional technology assumes that the lens is symmetrical with respect to the optical axis, and the symmetry of the plastic lens molded by the side gate is slightly disrupted. When holding the lens, sufficient consideration has not been given to the deformation of the molded lens.

There was a problem in that the lens shape was deformed, resulting in deterioration of accuracy and deterioration of optical performance.

The reason for this is that in the conventional molding technology described above, sufficient consideration is not given to the deformation of the molding die, which is the molding device, due to the pressure of the resin injected and filled during the molding process.
As shown in the figure, this is because a lens with deteriorated axial symmetry of lens thickness is molded.

When holding a lens in a lens barrel, the force that presses the thicker edge portion of the lens is greater, and the force that presses the thinner edge portion of the lens is smaller.

Due to the unbalance of the pressing force of holding the lens, the lens shape deforms unbalancedly. For this reason, the optical performance differs depending on the location on the screen, that is, it becomes unbalanced and deteriorates.

Next, we will discuss the reason why the thickness of the edge of the lens becomes axially symmetrical.

Molten resin is injected and filled into the cavity of the molding machine, and the pressure inside the cavity at that time is 50 to 1500.
It will be about Kg/cm2. Also inside the cavity.

When pressure is applied, the central part of the mold, ie, the sprue part and part of the runner as shown in FIG. 13, deforms so as to expand.

For example, when carbon steel or stainless steel is used as the mold material, the amount of deformation is tens to hundreds of microns.

When the mold is deformed in this way, the amount of filling is different between the center and the periphery of the mold, resulting in the edge of the lens being thicker at the center of the mold and thinner at the periphery, that is, on the outside.

As mentioned above, the thickness of the edge of a molded plastic lens is non-uniform, and when it is held in a lens barrel, the optical performance inevitably deteriorates.

In lens injection molding, since it is not possible to fill from the center of the lens, side gates have to be used, and the thickness of the lens surface and edge portion becomes non-uniform.

An object of the present invention is to provide an optical device that eliminates the influence of non-uniformity in the thickness of a molded lens when it is held in a lens barrel.

[Means for Solving the Problems] In order to achieve the above object, four or more protrusions or depressions are provided on both surfaces of the edge portion of the lens, and the lengths of the protrusions or depressions are manufactured with high precision. When holding this lens in a lens barrel, the protrusion or recess of the lens is held down by a stopper or spacing ring on the lens barrel, which allows the distance between the lenses to be attached with high precision, and also to hold the lens. The pressure needed to hold the lens is evenly applied all around the lens.

[Function] Provided on both sides of the edge of the lens. By adopting a lens barrel structure that presses the protrusion or depression, the gap between the lens stopper and the presser part of the spacing ring becomes uniform, and the pressing force is made even.

[Example 1] An example of the present invention will be described below with reference to FIG. 1st
The figure is a perspective view showing an embodiment of the present invention, and shows a partial sectional view. . 2 is a lens, and the lens 1 is composed of a lens surface portion 2 and an edge portion 3.

8 is a lens barrel, one end of the lens barrel 8 has a stopper part 6a, and the other end does not have a stopper part. 9 is an interval ring,
Both ends of the spacing ring have holding portions 6b. Insert the lens l and spacing ring 9 into the lens barrel 8, hold it with the cover material 10, and tighten the screws 11.
to construct an optical system.

The present invention includes protrusions 41a on both sides of the edge portion 3 of the lens 1,
42a, 43a, 41b, 42b, 43b
(In the figure, 42b corresponding to 42aL is hidden, and the protrusion 42b is omitted.) The length of these protrusions is manufactured with high precision and is held in the lens barrel 8. .

In the lens holding method, if the thickness of the edge portion 3 of the lens 1 is made uniform by lens molding, no problem will arise in optical performance. However, in conventional molding equipment, the lens I
The thickness of the edge part is not uniform. The reason for this will be explained using FIGS. 14 and 15.

FIG. 14 is a sectional view of a mold of a conventional molding device. In FIG. 14, 101 is a fixed type, 102 is a movable type, and 10
3 is a spacer block, 104 and 105 are adapter plates, 106 is a cavity, 107 is a sprue, 108 is a runner, 109 is a gate, +10 is an ejector plate, 113 and 114 are insert pieces, and 115 is a protruding bottle.

In FIG. 14, a plastic lens is molded by injecting a mass of molten resin from a sprue 107 in the center of the mold.

The injected resin passes through the runner 108 due to the injection pressure.
It passes through gate 109 and is distributed, filling each cavity 106 with a side cage. Then, heat is applied using a temperature controller (not shown) provided in the fixed mold 101 or the movable mold 102 to form the mold.

FIG. 15 shows the structure of the mold during molding. Due to the pressure of the resin injected and filled during the molding process, as shown in FIG.
deforms so that it expands. As a result, as mentioned above, the amount of resin filled in the center and periphery of the mold is different, and the first
As shown in FIG. 3, the thickness of the edge of the lens is thick on the gate side (center of the mold) and thinner on the opposite side (periphery of the mold). Therefore, in the conventional lens holding method, the inter-lens distance layer is determined and held by the thicker edge of the lens, which causes errors in lens position and deteriorates optical performance.

The lens of one embodiment of the present invention shown in FIG. 1 is shown in FIG. 2 (A
) and shown in FIG. 2(B). Figure 2 (A) and Figure 2 (
B) is a case where three protrusions are provided on each side of the edge portion 3 of the lens 1. As described above, the thickness of the edge portion 3 of the lens 1 is the thickness t of the edge on the gate side, as shown in FIG.
is the largest, and the thickness L2 of the edge opposite to the gate side is the smallest. Therefore, the thickness of the protrusion 4 provided on the edge 3 of the lens 1 is made larger than the thickness of the edge, which is the largest.

It is also necessary to make the thickness of the protrusions highly accurate, so that the plane formed by the tips of the protrusions 41a, 42a, 43a on one lens surface side and the protrusions 41b, 42 on the other surface side.
b, parallel to the plane formed by the tip of 43b, and parallel to the plane perpendicular to the optical axis of the lens. Therefore, the lens thicknesses of the tip portions 51a, 52a, 53a of the protrusion and the tip portions 51b, 52b, 53b of the other protrusion are all equal.

Next, FIG. 3 shows a lens barrel according to an embodiment of the present invention that holds the above-mentioned plastic lens. FIG. 3 shows a state in which one lens of the present invention is assembled into a lens barrel.

In the lens barrel of FIG. 3, the lens of the present invention is fixed by supporting parts 6a and 6b, but the supporting part 6 that supports the lens
The planes a and bb are configured to be parallel. Planar parts 71a, 72a, 73a, 71b, 72b of this support part
, 73b, the projection of the lens 4]a, 42
a, 43a, 41b.

42b and 43b.

In this way, it becomes possible to make the pressing force for holding the lens 1 uniform, and an optical device with excellent optical performance can be realized.

Next, a molding apparatus for manufacturing the lens 1 of the present invention will be described.

FIG. 10 shows a cross-sectional view of the main parts of the molding apparatus of the present invention, which actually molds lenses. Figure 10 shows
This is an embodiment of a main part of a movable mold of a molding machine for injection molding the lens shown in FIG. 2. The structure is basically the same as the conventional structure shown in FIG. An insert piece 114 for shaping the lens surface is inserted into the movable mold 102, and a recessed portion 116.11 is formed in the portion of the insert piece 114 that shapes the edge portion 3 of the lens 1.
7.118 has been established. This recess is for forming the protrusion of the lens shown in FIG.

Since the protrusion in Fig. 2 is parallel to the plane perpendicular to the optical axis direction of the lens, the depth Q of the recess of the molding device is
In FIG. 10, the same view is taken from the AA' plane.

The structure of the mold that forms the depressions in this way will be described below.

As shown in one embodiment in FIG. 4, in order to provide recesses in both the fixed type and the movable type, a recess amount adjustment pin and a recess amount adjustment mechanism are provided in the fixed type and the movable type. Recess amount adjustment pin 1
One recess amount adjustment mechanism is connected to each recess.

The movable recess amount adjustment mechanism is the ejector plate 110.
The structure is such that it moves on the contact surface with the

Further, the depression amount adjustment mechanism is provided with an inclined surface, and the rA node pin connected to the depression amount adjustment pin on the inclined surface is configured to move on the inclined surface of the pin adjustment mechanism.

In other words, in FIG. 4, when the pin adjustment mechanism moves to the right on the surface of the ejector plate 110, the adjustment pin moves upward, and when it moves to the left, the adjustment pin moves downward. 5 Therefore, the amount of recess is variable. It can be done. The fixed type also has a similar mechanism.

Next, the entire molding apparatus for molding the lens 1 of the present invention will be described.

The lens shown in FIG. 2 of the present invention is entirely made of plastic, including the protrusions.9 FIG. 1 is a partial sectional view of a molding apparatus for injection molding the lens 1 shown in FIG. shows.

In the molding apparatus shown in FIG. 4, 101 is a fixed type, +02 is a movable type, 103 is a spacer block, 104 and 1.0
5 is an adapter plate attached to a molding machine (not shown), 106 is a cavity, 109 is a gate, 110 is an ejector plate, 113 and 114 are input pieces, 116 is a through hole, and 115 is an adjustment pin provided in the through hole 116. , 1.
20 is a pin adjustment mechanism, 123 is an inclined surface, and 125 is a positioning device.

In FIG. 4, the lens is formed by filling a cavity 106 with molten resin from a cage 109. The mold is provided with a through hole 116 passing through the movable mold, the fixed mold, and the insert piece. This through hole 116 is provided with an adjustment pin 115, and this adjustment pin 115 is movable. .

The adjustment pin 115 is attached to the inclined surface 123 of the pin adjustment mechanism 120.
and by moving the pin adjustment mechanism 120, the adjustment pin 1
13 can be moved. A positioning device 125 is a part that quickly moves the pin adjustment mechanism 120, and the pin adjustment mechanism 120 is operated via a drive section 125b.

The relationship between the change in length of the drive portion 125b of the positioning device w125 and the amount of movement of the adjustment pin 115 is determined by the inclination θ of the inclined surface 123 of the recess adjustment mechanism 120. In other words, the drive unit)2.
Change in length of 5b. ΔQ2. If the amount of movement of the recess amount adjusting pin 115 is ΔQ2, then 5 ΔQ = ΔQ×anO. If the slope O is made smaller, ΔQ2 becomes smaller,
It is possible to adjust the recess amount adjustment pin 115 minutely, that is, with high precision.

For example, if θ2l°, Δρ□ = 0.1 mm and Δp
2=0.0017mm. In this case, the drive unit 125
If the length b is adjusted with an accuracy of 0.111 m, the recess i adjustment pin 115 can be adjusted with an accuracy of 50.002 mm or less. Also, the amount of movement of the recess amount adjustment pin 115 is 10
Since the length is often 0 μm or less, it is sufficient for the length change axis of the quick-acting portion 125b to be about 6 mm.

The positioning device 125 includes a drive section 125b and an adjustment section 12.
5a, an extrusion section 12Dc is provided. The adjustment section 125a is composed of, for example, a micrometer, and serves as a mechanism for adjusting the length of the drive section 125b. A push-out portion 125c is provided at the tip of the quick-acting portion 125b, and is connected to and fixed to the depression amount adjustment mechanism 120.

Therefore, by adjusting the adjustment section 125a of the positioning device ff1125, the length of the drive section 125b changes, the extrusion section 125c moves, and the connected depression amount adjustment mechanism 120 moves accordingly.

Next, the shape of the protrusion of the plastic lens will be described.

Although the shape of the protrusion in this embodiment in FIG. 2 is cylindrical, another embodiment is shown in FIGS. 5 and 6.

FIG. 5 shows a case where the protrusion is a prism, and this case also has the same effect as a cylinder. The cross-sectional shape of the prism is a polygon larger than a triangle. Three or more such prisms are provided on each side of the edge portion.

FIG. 6 shows a crescent-shaped pillar in which the cross section of the protrusion is crescent-shaped, and has the advantage that the surface to be held by the protrusion is larger than that in FIGS. 2 and 5. In the case of such a crescent-shaped protrusion, the number of protrusions can be maintained at two or more.

Up to now, we have described an optical device in which a protrusion is provided on a plastic lens and the protrusion is held. However, as another embodiment of the present invention, the protrusion may be formed into a recessed part without any deterioration in mounting accuracy.

That is, as shown in FIG. 7, a recess is provided at the edge of the plastic lens. The structure of the molding device at this time is
In FIG. 4, the adjustment pin protrudes from the through hole to form a protrusion structure.

When a plastic lens is molded with such a molding structure, a recessed portion can be provided at the edge portion.

When the lens is held in the lens barrel 8, a portion of the stopper and the spacing ring of the lens barrel 8 are provided with protrusions that fit into recesses in the edges of the lens. In this manner, the lens barrel structure is such that the lens is pressed and held using a spacing ring or the like provided with a protrusion.

In this way, even in an optical device in which a concave portion is provided at the edge of a plastic lens, deformation does not occur when the lens is held, so that optical performance does not deteriorate. Therefore, even in such a structure, the effect remains the same.

Next, a case will be described in which a protrusion and a recess are provided at the edge of the lens.

FIG. 8 shows a case where a protrusion and a recess are provided on the edge of the lens. Further, FIG. 9 shows the case where the lens is held in the lens barrel. The structure of the molding device that provides a protrusion and a recess on the edge of the lens is such that, as shown in FIG. 4, one of the adjusting pins protrudes into the cavity and the other has a recess. With such a structure of the molding apparatus, the lens shown in FIG. 8 can be formed.

Furthermore, when holding it in the It barrel 8, the stopper part of the lens barrel 8 and the spacing ring 9 are also provided with protrusions and recesses, which fit and attach when the lens barrel 8 is held.

Even in such a structure, the plastic lens can be held without being deformed.

Next, a case will be described in which a protrusion on the edge of a plastic lens is externally attached.

FIG. 11 shows an embodiment in which a protrusion is externally attached.

In FIG. 11, a connecting rod, which is an integral part, is formed on the edge of the lens by insert molding.

In such a lens edge structure, as described above, the two planes formed by the tips of the connecting rods are parallel and also parallel to the plane perpendicular to the optical axis.

Another example of external attachment is shown in FIG. A screw hole is provided at the edge of the lens, and a metal or plastic screw is attached to the screw hole to form a protrusion.

In this threaded structure as well, the planes formed at the tips of the threaded portions are parallel and parallel to the plane perpendicular to the optical axis, as described above.

When the protrusion on the edge of the lens described above is attached externally, the structure for holding it in the lens barrel 8 is the same as the holding structure shown in FIG. 3.

Even if an external protrusion is provided on the edge of the lens in this way, the effect remains the same.

Next, when holding a lens with a protrusion on the edge in the lens barrel 8, a recess is provided in a part of the stopper of the lens barrel 8 and a holding part of the spacer ring 9, so that the protrusion of the lens 1 can fit into the lens. It has a lens barrel structure.

Providing a recessed portion in the tIt cylinder portion or the spacing ring in this manner enables positioning.

In addition, in the structure of the molding device of the present invention, an adjustment pin is provided to provide a protrusion or a recess at the edge of the lens. It is also possible to use both.

That is, in FIG. 14, the structure of the ejecting pin 115 is similar to the adjusting pin of the present invention, by providing a hole penetrating the fixed mold or movable mold of the molding device, inserting the pin into the through hole, and protruding the pin after molding. This is to remove the lens that is in close contact with the entry piece. By using this protruding pin structure as the adjusting pin structure of the present invention, the structure of the molding device does not become complicated and is economical.

[Effects of the Invention] As described above, in the present invention, protrusions and depressions are provided on the edge of a molded plastic lens, and the thickness of the protrusions and depressions is controlled by the pressure inside the mold cavity and the thickness of the protrusion and depression. Because it is molded without being affected by thermal expansion, it can be made with high precision, and even if the thickness of the edge part is uneven, the protrusions and depressions of the edge part are retained in the lens barrel. Does not cause local deformation of the lens during or after holding,
It can maintain the same high precision as when it was molded, and does not cause any deterioration in optical performance. Therefore, a highly accurate optical device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional perspective view of a lens barrel incorporating a plastic lens according to an embodiment of the present invention, FIG. 2 is a plastic lens according to an embodiment of the present invention, and FIG. FIG. 4 is a cross-sectional view of a portion of the molding apparatus of the present invention that molds a plastic lens. No. 551A is a plastic lens according to another embodiment of the present invention. FIG. 5 shows a plastic lens according to another embodiment of the present invention, FIG. 7 shows a plastic lens according to another embodiment of the present invention, and FIG. 8 shows a plastic lens according to another embodiment of the present invention. The figure is a partial cross-sectional view of the lens barrel when the lens of the present invention is held in the cartridge, Figure 10 is a cross-sectional view of the main part of the molding device for molding the lens of the present invention, and Figure 11
The figure shows another example of a plastic lens of the present invention with externally attached protrusions, FIG. 12 shows another example of a plastic lens with externally attached protrusions of the present invention, FIG. 13 shows a conventional plastic lens 2, and FIG. 14 shows a conventional plastic lens. A cross-sectional view of a molding die for a conventional molding device,
FIG. 15 is a sectional view of the molding die during the molding process. 1 Plastic lens 2 Plastic lens edge section 9 Spacing ring 41a, 428.43a - Projection 106 - Cavity 113.1.14 Input piece... Figure 2 tj] Figure 3 ¥74 (A) b No. 7 (A) (B) b Note Figure 2 (A) (B) Figure 9 Otsu 6t, 67-1 81 b Funeral Figure 70 (A) 8' (B) 1oq' Noah 5 114 Figure 11 Figure 12 Figure 13 Shiro〈A) (F3) il; Gate Jun. 11 Koba 43 t2: Anti-genitoi purchase Koba 47 7t> f: / z % 14 Figure //ρ ll1 112 H3 //4 III

Claims (1)

[Claims] 1. A plastic lens molded by injection molding or the like;
An optical device for holding the plastic lens in a lens barrel, characterized in that a protrusion or a recess is provided on the edge of the plastic lens, and the protrusion or the recess is held. 2. The plastic lens optical device according to claim 1, wherein the thickness of the protrusion provided on the plastic lens is greater than the thickness of the edge of the plastic lens. 3. A through hole is provided in the mold for molding the plastic lens, and a pin is inserted into the through hole in order to form a protrusion or a recess to be provided on the plastic lens at the edge of the plastic lens. A molding apparatus characterized in that the pin is fixed in a cavity or in a protrusion, and the plastic lens is shaped with a protrusion or a depression. 4. In the molding device, a pin in the through hole can be adjusted to shape the protrusion or depression of the plastic lens, and the adjustment pin can be adjusted from outside the mold. The molding apparatus according to claim 3, characterized in that: 5. A claim characterized in that, in the molding apparatus, the adjustment pin mechanism for shaping the protrusion or recess of the plastic lens also serves as an ejection pin structure for removing the plastic lens from the mold after molding. Item 3. The molding device according to item 3.