JP2011018081A - Lens system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens system for satisfactorily preventing displacement of an optical axis between lenses and a lens barrel and displacement of an optical axis between the lenses, even if the lens system is affected by the temperature or humidity changes.SOLUTION: The lens system holds the lenses 2 to 4, which are made of plastics and have circular peripheries, in a lens barrel 1 made of plastic which has inner circumferential face in a shape of a polygon shape having 8 or more angles, such that the external circumferential faces of the lenses 2 to 4 are brought into pressure contact with the polygonal inner circumferential face. The lens system has pressure contact parts 32a, 32b, and 32c, disposed near gate trace parts 13, 18, and 23 where the optical axis greatly deviates and on the right and left sides of each of the gate trace parts 13, 18, and 23, to come into pressure contact with the outer circumferential faces of the lenses 2 to 4 and the internal circumferential face of the lens barrel 1. Displacement of each of the gate trace parts 13, 18, and 23 are made to be suppressible by the pressure contact parts 32a, 32b, and 32c.

Description

  The present invention relates to a lens device for inserting and fixing a lens used in a camera or the like in a lens barrel.

  A digital camera, a camera for a mobile phone, and the like use a lens device in which one or a plurality of lenses are inserted and fixed in a lens barrel. Such a lens device is manufactured by performing centering so that the optical axis of the lens and the lens barrel and the optical axes of the plurality of lenses coincide with each other, and inserting and fixing the lens in the lens barrel.

  On the other hand, in this type of lens device, a plastic lens, a plastic lens barrel, or the like is used from the viewpoint of being easy to obtain an inexpensive and arbitrary shape.

  However, such plastic lenses and lens barrels are prone to expansion and contraction due to changes in temperature or humidity, and even if the lens is centered when inserted and fixed in the lens barrel, the temperature and humidity changes. As a result, the optical axis between the lens and the lens barrel or the lens is deviated, leading to a problem that the optical characteristics deteriorate.

In order to improve such a problem, in a lens device including a plastic lens and a lens barrel for holding the lens, the lens device projects from the inner surface of the lens barrel in the direction of the central axis (optical axis) of the lens barrel. And at least three protrusions are formed to hold the lens by contacting the outer peripheral edge of the lens and the diameter of a circle in which the tip of the protrusion is inscribed is supported by the protrusion. The lens is decentered even in a dimensional change due to an environment such as temperature, humidity, etc. by making the lens device smaller than the outer diameter of the lens, and making the rigidity of the cylindrical member smaller than the rigidity of the plastic lens, A lens device that prevents deformation is proposed (see Patent Document 1 below).

  According to this proposal, since the lens receives a force such that its center always coincides with the center of the lens barrel, it can be prevented from being decentered and held at a predetermined position in the lens barrel. There is a problem that the optical axis shift between the tube and the lens cannot be sufficiently suppressed.

JP-A-4-204408

  An object of the present invention is to solve the above-mentioned problems of the prior art and to satisfactorily suppress the deviation of the optical axis between the lens and the lens barrel and the deviation of the optical axis between the lenses even when the temperature and humidity change. It is to provide a lens device that can.

According to the present invention, a plastic lens having a circular outer periphery is pressed into a plastic lens barrel having a polygonal inner peripheral surface having eight or more corners, and the outer peripheral surface of the lens is pressed against the inner peripheral surface of the polygon. In the lens device to be held,
The pressure contact portions are provided symmetrically with respect to a line connecting the center of the gate trace portion formed on the outer periphery of the lens and the optical axis of the lens when the lens is injection-molded.

  As a result of intensive studies on the optical axis shift between the lens and the lens barrel and the lens when the temperature and humidity are changed, the inventors have examined the gate direction when the plastic lens and the lens barrel are injection molded. Since the flow orientation of the resin is different in the direction perpendicular to the gate, the roundness becomes, for example, an oval shape, and it has been clarified that it is difficult to ensure the roundness.

  In this state, when the lens and the lens barrel repeatedly expanded and contracted due to the influence of temperature change and humidity change, the roundness easily decreased, and the roundness decreased in both the lens and the lens barrel. In this case, the coaxiality is lowered, and as a result, the lens and the lens barrel or the lenses are displaced from each other in the optical axis.

  Although the lens itself is essentially in a form that does not easily change the roundness, in the case of a plastic lens manufactured by an injection molding method, there is always a gate for filling the resin in the mold, and this part is a mirror. In order to efficiently store the lens in the cylinder, the lens has a flat surface partially cut out of the annular outer diameter, that is, a so-called D-shaped lens shape.

  In other words, if both the lens and the lens barrel are round, or one of them is round, the deformation when affected by changes in temperature and humidity, that is, the roundness change has little influence on the coaxiality. Conceivable. However, when both the lens and the lens barrel are manufactured by the injection molding method and both are inferior in roundness, the deformation caused by the influence of the temperature and humidity change, that is, the roundness change becomes the coaxiality degradation.

  Furthermore, the gate trace portion of this lens is more likely to have a relatively large gap when the lens is housed in the lens barrel than the outer peripheral portion of other lenses, and the light from the gate trace portion is subject to changes in temperature and humidity. I have found out that the bias of the shaft is large.

  As a result of further investigation based on this investigation, a plastic lens having a circular outer periphery is placed in a plastic lens barrel having a polygonal inner peripheral surface of eight or more corners, and the lens is disposed on the inner peripheral surface of the polygonal shape. In the lens device that holds the outer peripheral surface of the lens in pressure contact, pressure contact portions that are in close contact with the outer peripheral surface of the lens and the inner peripheral surface of the lens barrel are provided in the vicinity of the gate trace portion and on the left and right sides of the gate trace portion, respectively. The portion can suppress the deviation of the optical axis due to the gate trace portion.

  The gate trace part in the present invention is not limited to the case where a part of the trace of the introduction part (gate) for introducing the plastic material melted at the time of the injection molding of the lens into the molding die remains in the molded lens product. This includes the case where the entire gate trace of the lens is cut and removed so that no trace remains.

  The pressure contact portion is as close as possible to the gate trace portion, and further provided on both the left and right sides to suppress the deviation of the optical axis due to the gate trace portion. The bias can be effectively suppressed. In particular, there are at least a plurality of pressure contact portions on one side of the lower chord arc portion adjacent to the gate trace portion, preferably a plurality of lower chord arc portions on both sides, particularly symmetrical with respect to a line connecting the center of the gate trace portion and the optical axis of the lens. It is preferable to provide a plurality of them.

  If the shape of the inner peripheral surface of the lens barrel is not an octagon or more, it is not possible to sufficiently suppress the deviation of the optical axis between the lens barrel and the lens. For this reason, the setting of the press-fitting allowance has to be reduced, in which case the dimensional accuracy becomes more severe. In addition, it is necessary to adjust the number of corners during mold processing, and the number of processing steps increases.

  Further, the polygonal shape of the lens barrel and the length of each side surface of the inner peripheral surface may be unequal angles or unequal sides. It is easy and preferable.

  Further, as will be described later, when a lens barrel having a regular polygonal inner peripheral surface is manufactured, the machining method of the movable core pin having a cylindrical protrusion as a mold for forming the inner peripheral surface of the lens barrel is NC. First, a multistage coaxial process is performed on a cylindrical material so as to have a desired outer diameter using a lathe. Next, the machining center is used to rotate the multi-stage pin by a desired angle around the center of the multi-stage pin according to the number of angles of the polygon, and a part of the arc surface is linearly processed by an end mill. At this time, cutting is performed in advance, leaving a finishing machining allowance, and this is repeated for the required number of corners.

  The obtained movable core pin is incorporated into a mold, and injection molding is performed under a desired resin and molding conditions to obtain a molded product. Obtain the roundness and concentricity of this molded product, add the correction amount to the finishing allowance so that the roundness and concentricity are 0, and then adjust the cutting amount of the end mill using the machining center again. To get the final movable core pin. At this time, depending on the setting of the side length, it is preferable to leave the arc portion between the side surfaces because the molded product (lens barrel) can be released smoothly.

  Further, when a plurality of lenses are stored in the lens barrel, the plurality of lenses are arranged coaxially, but the plurality of lenses, that is, the lens having the largest absolute value of refractive power among all the systems. Then, when a lens with a large absolute value of refractive power is housed and fixed in the lens barrel so that the gate trace portion is in the same direction, the deviation of the optical axis due to the gate trace portion due to the change in temperature and humidity is The suppression effect by the pressure contact portion functions substantially the same, and even if it is biased to the gate trace portion side, the optical axis shift between the lenses becomes substantially the same, and the shift between the lenses is substantially less likely to occur.

  In the present invention, the reason why the inner peripheral surface of the lens barrel is a polygonal body is that even when the lens barrel is deformed due to the effects of processing errors, temperature changes, and humidity changes, there is little influence on the coaxiality. In the case of a triangle or a pentagon, the amount of coaxiality deviation becomes large even in the case of slight deformation.

  Further, since the press-fitting resistance of the lens increases as the number of corners increases, the setting of the press-fitting allowance must be reduced. In this case, the dimensional accuracy becomes more severe, and an arc portion is necessary. It is more desirable that the arc portion has an area ratio of 1 or less with respect to the flat portion with respect to the flat portion. The arc portion also plays an important role in verifying the accuracy of the movable core pin and the molded barrel.

  In addition, the lens gate trace can be accommodated within the outer diameter of the lens so that alignment can be performed simply by incorporating the lens into the lens barrel without any special gate treatment, enabling passive assembly. Therefore, an expensive alignment device is unnecessary and mass production is possible. In addition, it is possible to obtain a photographing lens with little misalignment between the lenses and little resolution degradation. Furthermore, even with respect to changes over time, such as deformation of the lens barrel after repeated heat cycle tests, misalignment is unlikely to occur, and resolution degradation is small, eliminating the need for adhesion between lenses or between the lens and the lens barrel. Become.

  In the present invention, a plastic lens having a circular outer periphery is placed in a plastic lens barrel having a polygonal inner peripheral surface of eight or more corners, and the outer peripheral surface of the lens is disposed on the polygonal inner peripheral surface. In the lens device held in pressure contact, pressure contact portions that are in pressure contact with the outer peripheral surface of the lens and the inner peripheral surface of the lens barrel are provided in the vicinity of the gate trace portion having a large displacement and on the left and right sides of the gate trace portion, respectively. Since the displacement of the gate trace portion is suppressed by this, it is possible to provide a lens device having excellent optical characteristics by suppressing the shift of the optical axis between the lens and the lens barrel or the lens.

It is sectional drawing of the lens apparatus which concerns on the Example of this invention. It is an exploded sectional view of the principal part of the lens device. It is a perspective view of the 1st lens used for the lens apparatus. FIG. 4 is a cross-sectional view taken along line a-a ′ of FIG. 3. FIG. 4 is a cross-sectional view taken along line b-b ′ in FIG. 3. FIG. 3 is a top view of the lens barrel shown in FIG. 2. FIG. 2 is an enlarged cross-sectional view in which a part cut along the line c-c ′ in FIG. 1 is cut out. It is sectional drawing cut | disconnected on the c-c 'line | wire of FIG. 1 at the time of arrange | positioning so that the gate trace part of a 1st lens may become parallel to the side inner surface of the inner peripheral surface of a lens-barrel. It is sectional drawing cut | disconnected on the c-c 'line | wire of FIG. 1 at the time of arrange | positioning so that the gate trace part of a 1st lens may oppose the connection part of the internal peripheral surface of a lens-barrel. It is sectional drawing of the shaping die for manufacturing the lens barrel used with the lens apparatus which concerns on the Example of this invention. It is a perspective view in the middle of processing (a) and after processing (b) of the core of the molding die for manufacturing the lens barrel used in the lens apparatus of the embodiment of the present invention. It is the upper surface schematic diagram for demonstrating the manufacturing method of the core of the shaping die for manufacturing the lens barrel used with the lens apparatus of the Example of this invention. It is the upper surface schematic for demonstrating the deformation | transformation state by injection molding of the lens barrel used with the lens apparatus of the Example of this invention. It is the upper surface schematic for demonstrating having corrected the deformation | transformation by the injection molding of the lens barrel used with the lens apparatus of the Example of this invention. It is sectional drawing which shows the lens apparatus of Example 1 of this invention. It is sectional drawing cut | disconnected by the part of the 1st lens of the lens apparatus of Example 5 of this invention.

  Embodiments of a lens apparatus to which the present invention is applied will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of the lens apparatus shown in Embodiment 1 according to the present invention, and FIG. 2 is an exploded cross-sectional view of the main part of the lens apparatus of the present invention.

As is apparent from FIGS. 1 and 2, the lens apparatus according to this embodiment includes a black lens barrel 1 made of a mixture of a polycarbonate resin having an outer diameter of 8 mm, a glass fiber, and a black pigment such as carbon black, and the lens barrel. 1 is a first positive lens 2 having a refractive power of 204 deopters having an outer diameter of 5.7 mm and made of an amorphous polyolefin-based resin that is press-fitted and held at a predetermined interval in the first lens. A refractive power of 38 having an outer diameter of 5.9 mm. Deopter second positive lens 3, refractive power with outer diameter of 6.4 mm −15 deopter correction lens 4, between positive lens 2 and positive lens 3, and between positive lens 3 and correction lens 4 Middle drawn part 5 made of synthetic resin film such as stretched polyester (PET) kneaded with carbon black, or a mixture of polycarbonate resin, glass fiber, and black pigment such as carbon black It becomes black lens holding member 6 which is basically composed.

  In the figure, 7 is an infrared cut filter that blocks long-wavelength light, 8 is a solid-state image sensor such as a CCD that converts an image formed by the lens device into an electrical signal, and 9 is a lens pressing member 6 that is bonded to the lens barrel 1. An adhesive to be fixed, 60 is a wiring, and 61 is a printed wiring board. The focal length f of the entire lens apparatus is 4.8 mm, and the diagonal length of the solid-state imaging device is 6.2 mm.

  The first positive lens 2 is a perspective view of FIG. 3, a cross-sectional view cut along the line aa ′ in FIG. 3 (FIG. 4), and a cross-sectional view cut along the line bb ′ in FIG. As shown, the first optical functional surface 10a having a convex aspherical surface as viewed from the object side is provided on one surface of the central portion, and the second optical surface having a concave aspherical surface as viewed from the image side is provided on the opposite surface. A functional surface 10b is provided, and an annular flange portion 11 is provided on the outer periphery of the optical functional surfaces 10a and 10b.

  Since this lens 2 is molded by injection molding from an amorphous polyolefin-based resin as described above, a gate trace portion 13 having a flat surface portion 12 is formed on a part of the outer peripheral surface of the lens 2, and the other portions are The outer circumferential surface 14 has an arc shape centered on the center of the lens.

  Similarly, the same shape is adopted in the positive lens 3 and the correction lens 4 which are the second lenses. In the second lens 3, optical function surfaces 15a and 15b are formed, an annular flange portion 16, a flat surface. In the correction lens 4, the optical function surfaces 20 a and 20 b are respectively formed on the surface 17, the gate trace portion 18, and the arc-shaped outer peripheral surface 19, and the annular flange portion 21, the flat surface 22, the gate trace portion 23, and the arc-shaped outer peripheral surface. 24 is formed.

  The first lens 2, the second lens 3, and the correction lens 4 are formed so that their outer diameters are sequentially increased from the object side, and the optical axes 2 a, 3 a, and 4 a of these lenses are substantially centered. positioned.

  On the other hand, the lens barrel 1 is formed by injection molding using the above-mentioned mixture. As shown in FIG. 2, the lens barrel 1 has a through hole 25 having a function of an optical diaphragm at the center of the bottom, and the first lens 2 There are a first step portion 26 for storing, a second step portion 27 for storing the second lens 3 and the light-shielding stop 5a, and a third step portion 28 for storing the correction lens 4 and the light-shielding stop 5b. 27 and 28 have side faces 29, 30, and 31 having regular dodecagonal shapes.

  The inner diameters of the inscribed circles of the dodecagonal shape are slightly smaller than the outer diameters of the first lens 2, the second lens 3, and the correction lens 4 (0.01 to 0.03 mm in diameter). When the first lens 2, the second lens 3 and the correction lens 4 are inserted into the step portions 26, 27 and 28, respectively, a press-fit state is obtained, and the side inner surfaces 29, 30 and 31 and the outer peripheral surfaces 14, 19 and 24 of the lens are Are pressed in a pressure contact portion to be described later, and each lens 2, 3, 4 is in a state where the optical axis 1 a of the lens barrel 1 and the optical axes of the angular lenses 2, 3, 4 are aligned in the lens barrel 1. Will be stored and held. Reference numerals 51, 52 and 53 denote arc-shaped connecting portions formed corresponding to side surfaces 44a, 44b, 45a, 45b, 46a and 46b of the movable core pin 39 which will be described later.

  When the first lens 2, the second lens 3, and the correction lens 4 are housed in the lens barrel 1 having such an inner peripheral surface, as shown in FIGS. 1 and 6, the circles of the lenses 2, 3, 4 are used. If the arcuate outer peripheral surfaces 14, 19, 24 are inserted so as to be inscribed in the regular dodecagonal side inner surfaces 29, 30, 31 of the lens barrel 1, they are properly press-fitted and held.

  In the gate trace portions 13, 18, and 23 of the lenses 2, 3, and 4, as shown in FIG. 7, the gate trace portion 13 is located closer to the center than the arc-shaped outer periphery of the lens 2, as shown as a representative example. The gate trace portion 13 does not come into pressure contact with the inner side surface 29, and the gap 33 is larger than the pressure contact portions 32a and 32b between the arc-shaped outer peripheral surface 14 of the lens 2 and the side inner surface 29. The roundness is reduced by expansion and contraction, and the optical axis is biased toward the gate trace portion 13 side in the vicinity of the gate trace portion 13 around the reference line 35 connecting the center 34 of the gate trace portion and the optical axis 2a, and the right and left It can be suppressed by providing pressure contact portions 32a and 32b that are in pressure contact with the lens outer peripheral surface 14 on both sides.

  FIG. 8 and FIG. 9 are diagrams showing a pressure contact state between the inner side surface 29 of the first step portion 26 of the lens barrel 1 and the outer peripheral surface 14 of the first lens 2 as a representative example. In FIG. FIG. 9 shows a case where the gate trace portion 13 is inserted in parallel with the gate trace portion 13. In FIG. 9, the arrangement of the gate trace portion 13 of the lens 2 and the side inner surface 29 of the lens barrel 1 is different from the case of FIG. 8 shows a case where the connecting portion 36 at the crossing portion is inserted so as to face the gate trace portion 13, and in the case of FIG. 8, the support point is closer to the gate trace portion, and the deviation of the optical axis becomes smaller. Therefore, it is preferable.

  Next, a manufacturing method of the lens barrel 1 having the regular dodecagonal side inner surfaces 29, 30, and 31 will be described. The lens barrel 1 includes a fixed core 37a, a fixed core pin 37b, a movable core 38, and a movable core 38, as shown in FIG. It is formed by using a mold combined with the movable core pin 39 and injection molding a molten resin made of the mixture into a cavity 40 defined by combining these molds. In addition, 59 in FIG. 10 is a gate part into which molten resin is injected into the cavity 40.

  In this case, as shown in FIG. 11, the movable core pin 39 includes a first protrusion 41 and a second protrusion 42 corresponding to the first step 25, the second step 26 and the third step 27 of the lens barrel 1. And the third projecting portion 43, and the peripheral surfaces of these projecting portions 41, 42, 43 have twelve side surface portions 44, 45, 46 as shown in FIG. ing.

  A regular dodecagonal movable core pin 39 having such side surface portions 44, 45, 46 has a first projecting portion as shown in FIG. 12 (in this figure, the first projecting portion is shown as a representative example). 41, using a milling center (not shown) end mill 47 from a cylindrical body having the second projecting portion 42 and the third projecting portion 43, a part of the arc surface of the projecting portions 41, 42, 43 is cut into a predetermined shape. If it cuts by quantity, the movable core pin 39 which has a regular dodecagonal side surface part 44,45,46 on the surrounding surface of each protrusion part 41,42,43 can be manufactured easily.

  As a manufacturing method of the movable core pin 39, as shown in FIG. 11 (a), an NC lathe (not shown) is used to first perform a multistage coaxial process so that a cylindrical base material has a desired outer diameter. Next, the coaxial multi-stage pin obtained by using a machining center (not shown) is rotated by 30 degrees around the center of the multi-stage pin according to the polygonal angle of 12 angles, and a part of the arc surface is formed by the end mill 47. Straight line processing. At this time, a regular dodecagonal body is obtained by carrying out incision machining in advance, leaving a machining allowance for finishing, and repeating this for 11 times. Similarly, by repeating this for three stages, the product before correction of the movable core pin 39 is completed as shown in FIG.

  The obtained movable core pin is incorporated into a mold, and injection molding is performed under a desired resin and molding conditions to obtain a molded product. The roundness and coaxiality of this molded product are attached to a roundness measuring instrument, and the roundness and coaxiality of the injection molded product are obtained. After that, the cutting amount of the end mill 47 is determined again using the machining center, and the final movable core pin 39 is obtained.

In this case, the side surface portions 44, 45, 46 formed on the peripheral surfaces of the projecting portions 41, 42, 43 of the movable core pin 39 are located between the adjacent side surface portions 44a, 44b, 45a, 45b, 46a, 46b. Arc-shaped connecting portions 48, 49, and 50 in which a part of the cylindrical body remains can be provided. By using such a movable core pin 39, it becomes easy to release a molded product (lens barrel) at the time of injection molding of the lens barrel 1. When such a movable core pin 39 is used, the lens barrel 1 is injection molded. As shown in FIG. 9, the inner peripheral surface of each step portion is formed to have a flat side inner surface 29 and an arc-shaped connecting portion 51 between these side inner surfaces. (See Figure 9)
When the lens barrel 1 is injection-molded as described above, the inner peripheral surface 55a is hardly molded into a perfect circle, and is deformed into an ellipse with the gate trace portion 54 as the center, as shown in FIG. Cheap. Even in such a case, as described above, in consideration of the deformation amount, as shown in FIG. 14, the core is formed so as to have a polygonal inner peripheral surface 55b having a perfect circumscribed circle. The outer peripheral surfaces of the projecting portions 41, 42, and 43 of the 39 can be adjusted by being appropriately cut by the machining center 47.

  When the first lens 2, the second lens 3, and the correction lens 4 manufactured in this way are pressed into the first step portion 26, the second step portion 27, and the third step portion 28 of the lens barrel 1 and held. In addition, when the gate trace portions 13, 18, and 23 of the lenses 2, 3, and 4 are arranged so that their directions are different by 180 degrees as shown in FIG. When the optical axis shift is likely to occur in the A and B directions, and the gate trace portions 13, 18, and 23 of the lenses 2, 3, and 4 are in the same direction (arrow A direction) as shown in FIG. It has been found that the optical axis shift between the lenses hardly occurs even when the temperature is changed.

  The following table is arranged so that the orientation of the gate trace portions 13, 18, and 23 of the lenses 2, 3, and 4 is 180 degrees different in the lens barrel 1 having a regular dodecagonal inner peripheral surface according to the embodiment of the present invention. For the sample of five lens devices arranged in the same direction as in Example 1 (Example 2), the resolution immediately after the lens was assembled in the lens barrel 1 (initial) and -40 ° C. for 30 minutes The resolution after performing a temperature cycle test in which cooling and heating at 85 ° C. for 30 minutes and heating were repeated 200 cycles is shown.

Incidentally, the evaluation method was as follows.
The object distance is 1m, the light source is halogen white light, the object is a 30mm square perforated square chart. The frequency response component MTF (Modulation Transfer Function) was obtained. In the square chart, two directions perpendicular to each other were defined as sagittal and meridional components, respectively, and the two opposite sides were averaged. Further, the defocus position was an intermediate position between the peak positions of the sagittal and meridional when the center was 80 lines / mm, and the resolution value was the value when the contrast was 20%.

As the measurement position, eight points were measured every 45 degrees in the circumferential direction at the center and at a position where the image height was 70% with respect to the diagonal length of the solid-state imaging device of 6.2 mm. The table summarizes the central sagittal, meridional value, and the 8 points of sagittal and meridional values at 70% of the image height. The higher the numerical value, the higher the resolution.

  From the above results, in the case of Example 1, after the temperature cycle test, the resolution slightly decreases at “image height 70%”, but in the case of Example 2, the decrease is not so much observed. It is clear that the axis deviation is small.

Next, the same lens arrangement as in Example 2 is performed, and the polygonal inner peripheral surface of the lens barrel 1 is a triangular inner peripheral surface (Comparative Example 1), a hexagonal inner peripheral surface (Comparative Example 2), and eight The following table shows the results of measuring the initial and the resolution after the temperature cycle test for the rectangular inner peripheral surface (Example 3) and the hexagonal inner peripheral surface (Example 4).

  From the above results, those having the triangular inner peripheral surface shown in Comparative Example 1 and the hexagonal inner peripheral surface shown in Comparative Example 2 have a low initial resolution and a low resolution after the temperature cycle test, and cannot withstand practical use. From the results of Examples 3 and 4, the octagonal inner peripheral surface and further the hexagonal inner peripheral surface have higher resolution than the hexagonal inner peripheral surface shown in Comparative Example 2, and the polygon has a large number of corners. It is clear that having an inner peripheral surface is more effective.

  Next, an example (Example 5) in which the outer peripheral surface of a lens (represented by the first lens in this figure) is pressed against a lens barrel 1 having an unequal octagonal inner peripheral surface will be described.

  As shown in FIG. 16, in this example, the reference line 35 and the pressure contacts 32a and 32b, the pressure contacts 32a, and the pressure contacts 32b are defined with reference to the reference line 35 connecting the center of the gate trace 13 and the optical axis 2a. The connecting angles are 30 degrees each, and the other pressure contacts 32a and 32c, the pressure contacts 32c, and 32c and 32b are spaced by 60 degrees, respectively. In the adjacent region, the pressure contacts 32a and 32b are provided at a narrow interval.

  For this reason, when the pressure contacts 32a and 32b are formed within 45 degrees in the vicinity of the gate trace portion 13, and further, when the reference line 35 connecting the center of the gate trace portion 13 and the optical axis 2a is used as a reference, 90 ° is provided on both sides. It has been found that when two or more points are provided within the same range, the optical axis shift between the lens, the lens barrel, and the lens hardly occurs even when the temperature and humidity change. In this case, the second lens 3 and the correction lens 4 have the same configuration as that of the first lens.

The following table shows the results, and it is clear that the resolution of “image height 70%” is particularly improved as compared with the case of having the regular octagonal inner peripheral surface of Example 3.

  The lens device according to the present invention can be effectively used in small and light cameras such as small video cameras, in-vehicle cameras, surveillance cameras, digital cameras, and mobile phone cameras using a light receiving element such as CCD or CMOS. This is particularly effective when using several lenses rather than using a single lens.

  1: lens barrel, 2: first lens, 3: second lens, 4: correction lens, 2a, 3a, 4a: optical axis, 5a, 5b: light-shielding diaphragm, 6: lens pressing member, 7: infrared cut filter, 8: Solid-state imaging device, 9: Adhesive, 10a, 10b, 15a, 15b, 20a, 20b: Optical function surface, 11, 16, 21: Flange part, 12, 17, 22: Flat part, 13, 18, 23 : Gate trace portion, 14, 19, 24: Arc-shaped outer peripheral surface, 25: Through hole, 26: First step portion, 27: Second step portion, 28: Third step portion, 29, 30, 31: Side inner surface, 32, 32a, 32b, 32c: pressure contact part, 33: gap, 34: center of gate trace part, 35: reference line, 36: connecting part, 37a, fixed core, 37b: fixed core pin, 38: movable core, 39: Movable core pin, 40: cavity, 41: first protrusion, 42: second protrusion 43: 3rd protrusion part, 44, 45, 46: Side surface part, 44a, 44b, 45a, 45b, 46a, 46b: Adjacent side surface part, 47: End mill, 48, 49, 50: Connection part of movable core pin, 51 52, 53: Connecting portion of inner peripheral surface of lens barrel, 54: Gate trace portion, 55a, 55b: Inner peripheral surface, 59: Gate portion.

Claims (1)

A plastic lens having a circular outer periphery is held in a plastic lens barrel having a polygonal inner peripheral surface of eight or more corners, with the outer peripheral surface of the lens being pressed against the polygonal inner peripheral surface. In the lens device,
A lens apparatus, wherein pressure contact portions are provided symmetrically with respect to a line connecting a center of a gate trace portion formed on an outer periphery of the lens and an optical axis of the lens when the lens is injection-molded.

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