JP2002187168A - Mold for molding optical element and optical element molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain required optical capacity by preventing the deterioration of surface accuracy or the increase of residual strain in a release process by minimizing the resistance required in the release of a side surface even in an optical element having large wall thickness or large total length and a multi- cavity mold, to sufficiently satisfy required capacity as a scanning optical system by reconciling high surface accuracy and reduced residual strain even in a lens having large thickness or large total length of the scanning optical system and to sufficiently satisfy required capacity as the scanning optical system by reconciling high surface accuracy and reduced residual strain even in a prism of a photographing optical system. SOLUTION: In a mold for molding the optical element made of plastics having an optical functional surface and the side surface surrounding the optical functional surface, a mold member constituting other side surface part excepting a side surface part to which a gate is arranged is formed into a slide structure and, in a molded article taking-out process, the mold member is formed into a structure for ejecting and pushing out the molded article after releasing the mold member from the side surface of the molded article.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die and a molded product for molding a plastic molded product requiring high precision by injection molding, injection compression molding or the like. The present invention relates to a molding die and a molded product suitable for improving optical surface accuracy and reducing residual distortion when molding the plastic optical element of (1).

[0002]

2. Description of the Related Art Conventionally, in the injection molding of a plastic optical element used for a scanning optical system, particularly, a long plastic optical element, an optical surface accuracy is required when a molded product is released from a mold by a protruding pin. Often deteriorated and residual strain increased. In particular, when the thickness is large or the overall length is long, the area of the side portion that is not optically used becomes large, and as a result, the resistance required for releasing the side surface becomes large. In many cases, required optical performance cannot be obtained.

[0003] These problems are more likely to occur in multi-cavity dies such as two-cavity and four-cavity dies. In other words, as the number of pieces increases, the resistance required for release increases, and the balance of the resistance of each of the many cavities tends to be slightly lost. As a result, the molded product separates while losing its posture. The resistance required for the mold has increased, leading to a deterioration in surface accuracy and an increase in residual strain.

[0004]

As a conventional countermeasure for a mold, there is a method of increasing a draft angle of a side portion. However, there is a restriction on a size of an optical element in an optical design and a clamping force of a molding machine. Because of the restriction of the projected area from the upper limit of
The draft was limited and the required effect was not obtained.
There is also a method of reducing the surface roughness by polishing the mold surface in order to reduce the resistance required for mold release, but there is a limit in reducing the frictional force generated between the resin and the mold surface, and the required No effect was obtained.

In order to solve such a problem, as one means, when the mold is opened, of the two end faces substantially perpendicular to the optical function surface of the optical element, the surface near the outside of the mold is first released. Has proposed a method for preventing deformation of an optical surface.

[0006] However, such a method cannot provide a sufficient effect particularly on a thick-walled one or a long-sided one, and cannot satisfy the optical performance.

Therefore, a first object of the present invention is to minimize the resistance required for releasing the side surface of a mold having a large wall thickness, a long overall length, and a multi-cavity mold. It is an object of the present invention to provide a mold for molding an optical element which can prevent deterioration of surface accuracy and increase of residual distortion in a releasing step and obtain required optical performance.

It is a second object of the present invention to provide an optical element molded product that can obtain required optical performance even if it is thick or long.

Further, a third object of the present invention is to provide a scanning optical system having both high surface accuracy and small residual distortion, even if the scanning optical system has a large thickness or a long overall length. An object of the present invention is to provide an optical element molded product that sufficiently satisfies required performance.

Further, a fourth object of the present invention is to provide a photographic optical system which achieves both high surface accuracy and small residual distortion, even if the prism of the photographic optical system is thick or long. An object of the present invention is to provide an optical element molded product that sufficiently satisfies the required performance of the optical element.

[0011]

In order to achieve the above-mentioned object, a mold for molding an optical element according to the present invention comprises a mold for molding a plastic optical element having an optical function surface and a side surface surrounding the optical function surface. In the mold, a mold member constituting a side portion other than the side portion on which the gate is disposed has a slide structure, and in the removal process of the molded product, after releasing the mold member from the side surface of the molded product, the molded product Is configured to protrude and push out.

In the mold for molding an optical element of the present invention, the slide structure has a slide member forming a side surface of a molded product, an angular pin for slidingly operating the slide member, and the angular pin is engaged with the slide member. And a hole for an angular pin provided in the slide member.

Further, the optical element molded product of the present invention has an optical function surface and a side surface surrounding the optical function surface, and a mold member constituting a side surface portion other than the side portion where the gate is disposed has a slide structure. In the removal process of the molded product,
After the mold member is released from the side surface of the molded product, the molded product is molded by a molding die for an optical element configured to protrude and extrude the molded product.

Furthermore, the optical element molded product of the present invention is:
The optical element is a lens of a scanning optical system.

The optical element molded product of the present invention is characterized in that the optical element is a prism of a photographing optical system.

In the optical element molding die and optical element molded product of the present invention configured as described above, the final molded product can be obtained by releasing the side portions other than the gate portion from the molded product in advance. Protrusion, that is, at the time of mold release of the optical function surface, has the effect of significantly reducing the adhesive force between the molded product and the mold, especially in the case of thicker and longer lengths because the side area is large. In addition, the effect of reduction is large, and the resistance required for mold release is reduced even in multi-cavity production, so that the resistance of each of the multiple cavities is balanced and the state where the mold release resistance is small is maintained. can do. By such an action, the molded product can be released from the mold without being pushed by the protruding pin with excessive force and without generating excessive frictional force with the mold wall surface on the side surface. As a result, there is an effect that an optical element molded product which has satisfactory reproducibility of the surface accuracy of the optical function surface and a small internal distortion and sufficiently satisfies required optical performance, particularly a long optical element molded product can be obtained. In addition, by this, there are effects such as obtaining a reproducibility of the surface accuracy of the optical function surface and a small internal distortion, and obtaining a scanning optical system lens and a prism of a photographing optical system which sufficiently satisfy required optical performance. Other objects, features, advantages, and the like of the present invention will become apparent from the following detailed description with reference to the accompanying drawings.

[0017]

(Embodiment 1) FIG. 1 is a view of a mold for molding an optical element, which best shows the features of the mold according to the present invention, and shows a movable mold in a closed state. FIG. 2 is a cross-sectional view of the molding die of FIG. 1 cut along the center line of the molded product including the fixed side, as viewed from the parting surface side.

As shown, the molding die 1 of the present invention is used.
Reference numeral 0 denotes a fixed mold 11 and a movable mold 12, and the fixed mold 11 includes a fixed mounting plate 13, a fixed mold plate 14, and a fixed optical part insertion piece 15, The movable mold 12 is generally composed of a movable mold plate 16, a movable optical section insert 17, a receiving plate 18, a spacer block 19, a movable mounting plate 20, upper and lower ejector plates 21, 22, and a protruding pin 23. ing.

As shown in the drawing, in the first embodiment of the molding die of the present invention, the fixed side mold plate 14 of the fixed side mold 11 is provided.
Between the movable-side mold plate 16 of the movable-side mold 12 and the movable-side optical unit-insertion piece 17, and between the fixed-side optical unit-insertion piece 15 and the movable-side optical element-insertion piece 17. Is formed, the molten resin is filled from the nozzle opening 9 provided in the fixed-side mounting plate 13, and the optical element molded product 1 is injection-molded. At this time, the optical element molded product 1 has side surfaces 4a, 4b, 4c surrounding the optical functional surface, and the gate 2 and the optical element molded product 1,
The runner 3 is formed. Further, slide members 5a, 5b, 5c surrounding the optical element molded product 1, and angular pins 6a corresponding to the slide members 5a, 5b, 5c,
6b and 6c are provided.
a, 5b, 5c, the side surface 4a of the optical element molded product 1,
4b and 4c are formed respectively, and the slide member 5 is formed.
a, 5b, 5c sliding motion margins 7a, 7b, 7c
And angular pin holes 8a, 8b, 8c for the sliding operation corresponding to the sliding members 5a, 5b, 5c, respectively.

The fixed mold 11 is composed of a fixed mold plate 14 and a fixed optical part insert 15, and the optical function surface of the optical element molded product 1 is formed by the fixed optical insert 15. Is done. The movable mold 12 is composed of a movable mold plate 16 and a movable optical section insertion piece 17 corresponding to the fixed mold 11, and includes slide members 5a, 5b, 5c and angular pins 6a, 6b, 6c. And a protruding pin 23 are provided.

FIG. 3 is a plan view of the movable mold 12 in a state immediately before the molding mold of FIGS. 1 and 2 is opened and the optical element molded article 1 is protruded, as viewed from the parting surface. FIG. 3 is a cross-sectional view including a fixed mold.

As shown, the slide members 5a, 5a
It is shown that b and 5c are released from the side surfaces 4a, 4b and 4c of the optical element molded product 1 by the action of the angular pins 6a, 6b and 6c and the holes 8a, 8b and 8c for the angular pins. I have. When the mold is opened, the fixed-side optical part insertion piece 15 has already been released from the optical element molded product 1, and thereafter the movable side optical part insertion piece 17 and the optical element molded product 1 are separated by the operation of the protruding pin 23. The mold is performed, and the removal of the optical element molded product 1 is completed. In the operation of the protruding pin 23 at this time, the side surface 4 of the optical element molded product 1 is moved.
Since the portions a, 4b, and 4c have already been released, only a force that resists the adhesive force between the movable-side optical unit insertion piece 15 and the optical element molded product 1 is required. ,
Since the frictional force at the portions 4b and 4c is eliminated, the force applied to the protruding pin 23 is significantly reduced.

FIG. 5 is a perspective view showing a long optical element molded product 1 molded in such an injection mold.

Using a mold having the structure of the present invention and a mold of the prior art having no slide structure, the following specific molding was performed, and the results were compared and examined.

Lens: Toric lens of laser scanning optical system Length: 150 mm, Maximum thickness: 10 mm, Width: 18 mm Bus bar: aspherical surface, sagittal line: spherical surface Resin material: ZEONEX 480R manufactured by Zeon Corporation Molding conditions: mold temperature 120 ° C., resin temperature 270 ° C., injection pressure 1400 kg / cm ² Cooling time 480 seconds Resistance to protruding pins upon release: Mold of the present invention: 80 kgf / cm ² Conventional mold: 400 kgf / cm ² Accuracy: mold of the present invention: busbar shape error 50 μm, sagittal shape error 0.1 μm Conventional mold: busbar shape error 100 μm, sagittal shape error 0.5 μm Internal strain: mold of the present invention: birefringence Small enough to be used as a laser scanning optical system. Conventional mold: Large birefringence, not usable as laser scanning optical system.

As a result, in the mold of the present invention, the effects of reducing the release resistance, improving the shape accuracy, and reducing the internal strain can be confirmed. Only when the mold of the present invention is used,
A long optical element having sufficient optical performance as a trick lens of the laser scanning optical system was obtained.

According to the mold of the present invention, since the side portions 4a, 4b, and 4c of the molded article do not require a draft with respect to the mold, the draft is usually 5 to 10 degrees. The angle can be set to 0 degree, and the dimension in the width direction can be minimized even in a lens having a particularly large thickness.

Embodiment 2 Next, as another embodiment of the present invention, a prism of a photographic optical system as shown in FIG. 6 was formed. FIG. 6 is a view showing a molded photographing optical system prism according to the second embodiment of the present invention, and as shown, reference numerals 24a, 24b, 24c, 24d, 24e, 24e are provided.
f and 24g are optical function surfaces, and 25 is a gate. 26a, 26b, 2
6c, and a mold corresponding to the mold had a slide structure similar to that in the first embodiment. The results were compared using a mold having a slide structure according to the present invention and a mold having a conventional structure having no slide structure.

Lens: prism for camera photographing optical system Length: 40 mm, maximum thickness: 8 mm, width: 10 mm All seven surfaces are aspherical. Resin material: ZEONEX 480R, manufactured by Zeon Corporation Molding conditions: mold temperature 120 ° C., resin temperature 270 ° C., injection pressure 1200 kg / cm ² Cooling time 360 seconds Resistance to the protruding pin at the time of mold release: Mold of the present invention: 20 kgf / cm ² Conventional mold: 100 kgf / cm ² Shape accuracy: of the present invention Mold: shape error 1 μm Conventional mold: shape error 20 μm Internal distortion: mold of the present invention: small birefringence, can be used sufficiently as an imaging system, conventional mold: large birefringence, imaging system Cannot be used as

As a result, in the molding die of the present invention,
The effects of reduction of mold release resistance, improvement of shape accuracy and reduction of internal distortion can be confirmed. Only when the molding die of the present invention is used, an optical element with sufficient optical performance as a prism for a camera photographing system can be obtained. Was done.

According to the molding die of the present invention, the side surfaces 26a, 26b, and 26c of the molded product do not require a draft angle with respect to the die. The gradient can be set to 0 degree, and the dimension in the width direction can be minimized, especially for a thick lens.

In the present embodiment, the present invention has been described with respect to an injection mold for a plastic optical component. However, the present invention can also be applied to a compression mold and an injection compression mold for a plastic optical component.

As described above, according to the present invention,
Deterioration of surface accuracy and increase of residual distortion in the mold release process by minimizing the resistance required for mold release on the side surfaces of thick molds, long molds, and even multi-cavity molds. Is prevented, and a mold for molding an optical element, particularly a long optical element, having a required optical performance can be obtained.

Further, according to the present invention, an optical element, particularly a long optical element molded product, which can obtain required optical performance even if the thickness is large or the entire length is long can be obtained.

Further, according to the present invention, a lens of a scanning optical system can be obtained that has good reproducibility of surface accuracy of the optical function surface, small internal distortion, and sufficiently satisfies required optical performance.

Furthermore, according to the present invention, it is possible to obtain a prism of a photographing optical system which has good reproducibility of surface accuracy of an optical function surface, has small internal distortion, and sufficiently satisfies required optical performance.

[0037]

According to the first aspect of the present invention, there is provided a mold for molding a plastic optical element having an optical function surface and a side surface surrounding the optical function surface.
The mold member constituting the other side portion except for the side portion where the gate is arranged is configured as a slide structure, and in the removal process of the molded product, after releasing the mold member from the side surface of the molded product, the molded product is ejected. Since it is configured to be extruded, it is possible to minimize the resistance required for the release of the side surface even in thick and long molds, and even in multi-cavity molds. It is possible to provide a molding die for an optical element capable of preventing a deterioration in accuracy and an increase in residual distortion and obtaining required optical performance.

In the mold for molding an optical element according to a second aspect of the present invention, the slide structure includes a slide member forming a side surface of the molded product, an angular pin for sliding the slide member, and the angular pin. Since it is formed of the angular pin holes provided in the slide member so as to engage with each other, a required slide structure can be formed with a small number of members, and a reliable sliding action can be obtained.

According to a third aspect of the present invention, there is provided an optical element molded product comprising a mold member having an optical function surface and a side surface surrounding the optical function surface, and forming a side surface portion other than the side portion where the gate is arranged. After the mold member is released from the side surface of the molded product in the molded product take-out process,
Optical element molded product that can obtain required optical performance even if it is thick or long because it is molded by a molding die for optical element that is configured to protrude and extrude molded product Is obtained.

In the optical element molded product according to the fourth aspect of the present invention, since the optical element is a lens of a scanning optical system, the reproducibility of the surface accuracy of the optical function surface is good, the internal distortion is small, and the required optical performance is small. Is satisfied, the lens of the scanning optical system is obtained.

In the optical element molded product according to the fifth aspect of the present invention, since the optical element is a prism of a photographing optical system, the required optical performance is excellent in the reproducibility of the surface accuracy of the optical functional surface and the internal distortion is small. Is obtained in the photographing optical system.

[Brief description of the drawings]

FIG. 1 is an imaginary plan view of a first embodiment of an optical element molding die that best illustrates the features of the present invention, as viewed from a partying surface side of a movable die in a closed state.

FIG. 2 is a cross-sectional view of the mold of FIG. 1 cut along a center line of a molded product including a fixed side.

FIG. 3 is a plan view of the movable mold in a state immediately before the mold of FIG. 1 is opened and an optical element molded product is protruded, as viewed from a parting surface side.

FIG. 4 is a cross-sectional view of the mold of FIG. 3 cut along a center line of a molded product including a fixed side.

FIG. 5 is a diagram showing a toric lens of a laser scanning optical system, which is an optical element molded product molded in a molding die according to Example 1 of the present invention.

FIG. 6 is a view showing a prism of a photographing optical system which is an optical element molded product molded in a molding die according to Embodiment 2 of the present invention.

[Explanation of symbols]

 Reference Signs List 1 optical element molded product 2 gate 3 runner 4a side surface 4b side surface 4c side surface 5a slide member 5b slide member 5c slide member 6a angular pin 6b angular pin 6c angular pin 6a angular pin 7a slide operation 7b slide operation 7c slide operation 7a slide operation Operating margin 8a Angular pin hole 8b Angular pin hole 8c Angular pin hole 9 Nozzle opening 10 Injection molding die 11 Fixed side die 12 Movable side die 13 Fixed side mounting plate 14 Fixed side die plate 15 Fixed side Optical part insertion piece 16 Movable side mold plate 17 Movable side optical part insertion piece 18 Receiving plate 19 Spacer block 20 Movable side mounting plate 21 Upper ejector plate 22 Lower ejector plate 23 Protrusion pin 24a Optical function surface 24b Optical function surface 4c optical function surface 24d optical function surface 24e optical function surface 24f optical function surface 24g optical function surface 25 gates 26a side 26b side 26c side

Claims (5)

[Claims] 1. A mold for molding a plastic optical element having an optical function surface and a side surface surrounding the optical function surface, wherein a mold member constituting another side portion except a side portion on which a gate is arranged is formed by a slide structure. An optical element molding die having a structure in which, in a molded product removal step, the molded member is released from a side surface of the molded product, and then the molded product is protruded and pushed out. 2. The slide structure according to claim 1, wherein the slide member forms a side surface portion of a molded product, an angular pin for sliding the slide member, and an angular pin provided on the slide member so that the angular pin is engaged. The mold for molding an optical element according to claim 1, wherein the mold is formed from a hole. 3. A mold member having an optical function surface and a side surface surrounding the optical function surface and constituting a side surface portion other than the side portion on which the gate is disposed, has a slide structure, and in a step of taking out a molded product, An optical element molded product formed by releasing a mold member from a side surface of a molded product, and then molding the optical product by a molding die for an optical element configured to project and extrude the molded product. 4. The optical element molded product according to claim 3, wherein the optical element is a lens of a scanning optical system. 5. The optical element molded product according to claim 3, wherein the optical element is a prism of a photographing optical system.