JP7479974B2 - Lens unit - Google Patents

Description

The present invention relates to a lens unit in which multiple lenses are arranged on an optical axis.

Patent Document 1 discloses a lens unit used in optical equipment. The lens unit in Patent Document 1 includes multiple lenses arranged on an optical axis and a lens holder that holds the multiple lenses. The lens holder is a molded product in which a lens barrel (lens barrel) and a case (front case) that covers the barrel are molded as one unit. The gap between the first lens, which is the lens closest to the subject among the multiple lenses, and the barrel is sealed with an O-ring.

The lens unit of Patent Document 1 has a heater disposed inside the lens unit to prevent condensation from forming inside the lens unit when used outdoors. The heater is an electric heating wire disposed on the surface of a thermally conductive ring-shaped flexible printed circuit board (aperture plate). Electricity is passed through the electric heating wire to generate heat, thereby increasing the temperature around the lens.

JP 2019-168509 A

When forming a heating wire on the surface of a flexible printed circuit board, a conductive material is laminated on the surface of the flexible printed circuit board to form a pattern in the shape of the heating wire. At that time, the thickness and length of the conductor pattern are set so that the required amount of heat is obtained. However, if the accuracy of the pattern shape is low, the resistance value of the conductor pattern will vary, leading to variations in the amount of heat generated.

For example, one method for inexpensively manufacturing conductive material patterns is to create a conductive material film using photolithography and then form a pattern using wet etching, but this method results in a large variation in the pattern shape. As a result, the amount of heat generated by the heater differs for each individual lens unit, resulting in a problem of variation in condensation removal capacity.

In view of the above problems, the objective of the present invention is to suppress the variation in the amount of heat generated by a heater in a lens unit that uses a conductor pattern formed on a flexible printed circuit board as a heater.

In order to solve the above problem, the lens unit of the present invention has a first lens closest to the object side, a second lens arranged on the image side relative to the first lens, a lens holder including a first housing portion for housing the first lens and a second housing portion for housing the second lens, and a flexible printed circuit board including a heater, the first lens having an object side lens surface, an image side lens surface, and an image side flange surface surrounding the image side lens surface, the flexible printed circuit board having a flat portion along the image side flange surface and an extension portion extending radially outward, a power supply wiring is arranged on the extension portion, a heater wire connected to the power supply wiring is arranged on the flat portion, and the heater wire has multiple folded portions.

According to the present invention, since the first lens can be heated by the heater wire arranged on the flexible printed circuit board, it is possible to suppress the deterioration of optical performance due to condensation inside the lens unit. In addition, the heater wire has a plurality of folded parts. Therefore, after manufacturing the flexible printed circuit board with the heater wire, the resistance value of the heater wire can be measured for each individual unit, and if it differs from the target value, the heater wire can be short-circuited at the position of the folded part to bring the resistance value closer to the target value. This makes it possible to reduce the variation in the resistance value of the heater wire even if the shape accuracy of the length and thickness of the heater wire is low. Therefore, it is possible to reduce the variation in the heat generation amount of the heater, and the variation in the condensation removal ability of the lens unit can be reduced.

In the present invention, it is preferable that a short-circuit conductive material is provided attached to the folded portion, and the heater wire is short-circuited by the short-circuit conductive material. For example, if a conductive paste or conductive adhesive is used as the short-circuit conductive material, the heater wire can be easily short-circuited. Therefore, the resistance value of the heater wire can be easily adjusted.

In the present invention, it is preferable that the multiple folded portions are aligned along the edge of the flexible printed circuit board. In this way, the short-circuit conductive material can be easily attached to the desired position and range. Therefore, the resistance value of the heater wire can be easily and accurately adjusted.

In the present invention, it is preferable that the flexible printed circuit board has a protruding portion protruding radially outward from the planar portion, and the folded portion is disposed on the protruding portion. In this way, the folded portion for adjusting the resistance value of the heater wire is less likely to interfere with components (e.g., the second lens and the lens holder) disposed on the image side of the first lens. If the folded portion of the heater wire is sandwiched between the first lens and another component, there is a risk that the folded portions will be crushed and short-circuited. However, in this embodiment, since the folded portion is disposed on a protruding portion protruding radially outward, there is little risk that the folded portions will be crushed and short-circuited. In addition, there is little risk that the short-circuit conductive material attached to the folded portion will be crushed and spread to an unintended range, causing the heater wire to short-circuit at an unintended position. Therefore, the resistance value of the heater wire can be adjusted with high precision.

In the present invention, it is preferable that the flat portion is annular, the power supply wiring extends radially from the extension portion to the flat portion, and the heater wire is connected to a radially inner end of the power supply wiring. In this way, if the connection portion between the heater wire and the power supply wiring is located radially inner, it is easy to locate the folded portion of the heater wire radially outer. Therefore, it is easy to short-circuit the folded portion.

In the present invention, it is preferable that the flexible printed circuit board has an overcoat layer that covers the power supply wiring and the heater wire, and the folded portion has an exposed portion that is exposed from the overcoat layer. In this way, the heater wire can be protected by the overcoat layer. In addition, since the folded portion is exposed, the heater wire can be short-circuited simply by attaching a short-circuit conductive material. Therefore, the resistance value of the heater wire can be easily adjusted.

In the present invention, the heater wire includes a thin heater wire that is connected to the folded portion, and the width of the folded portion is greater than the width of the thin heater wire. In this way, there is less risk of the folded portion breaking.

In the present invention, the folded portion preferably includes a first portion connected to the heater wire and a second portion protruding from the first portion, and the line width of the second portion is greater than the line width of the first portion. In this way, the tip of the folded portion can be easily short-circuited, making it easy to adjust the resistance value of the heater wire. In addition, since the gap between adjacent folded portions is narrow, there is little risk of the short circuit being impossible due to misalignment or insufficient amount of short-circuit conductive material.

Next, in order to solve the above problem, the lens unit of the present invention has a first lens closest to the object side, a second lens arranged on the image side relative to the first lens, a lens holder having a first housing portion for housing the first lens and a second housing portion for housing the second lens, and a flexible printed circuit board having a heater, the first lens having an object side lens surface, an image side lens surface, and an image side flange surface surrounding the image side lens surface, the flexible printed circuit board having a flat portion along the image side flange surface and an extension portion extending radially outward, a power supply wiring is arranged on the extension portion, and a heater wire connected to the power supply wiring and a short circuit wiring are arranged on the flat portion.

According to the present invention, the first lens can be heated by the heater wire arranged on the flexible printed circuit board, so that it is possible to prevent condensation inside the lens unit and deterioration of optical performance. In addition to the heater wire, a short-circuiting wire is arranged on the flexible printed circuit board. Therefore, if the resistance value of the heater wire differs from the target value, the resistance value of the heater wire can be adjusted by connecting the short-circuiting wire to the heater wire, or by cutting either the heater wire or the short-circuiting wire. Therefore, even if the shape precision of the length and thickness of the heater wire is low, it is possible to reduce the variation in the resistance value of the heater wire and the variation in the amount of heat generated by the heater.

For example, a configuration can be adopted that includes a short-circuit conductive material that connects the short-circuit wiring and the heater wire. For example, if a conductive paste or conductive adhesive is used as the short-circuit conductive material, the short-circuit wiring and the heater wire can be easily short-circuited. Therefore, the resistance value of the heater wire can be easily adjusted.

Alternatively, a configuration can be adopted in which a cut portion is provided by a laser on either the short-circuiting wiring or the heater wire short-circuited by the short-circuiting wiring. In this way, the resistance value of the heater wire can be adjusted by cutting either the heater wire or the short-circuiting wiring.

In the present invention, it is preferable that the short-circuiting wiring is arranged on the edge of the flexible printed circuit board. In this way, the short-circuiting conductive material can be easily attached to the target position and range. Therefore, the resistance value of the heater wire can be easily and accurately adjusted.

According to the present invention, since the first lens can be heated by the heater wire arranged on the flexible printed circuit board, it is possible to suppress the deterioration of optical performance due to condensation inside the lens unit. In addition, the heater wire has multiple folded parts, or the heater wire and the short-circuiting wire are arranged on the flexible printed circuit board. Therefore, after manufacturing the flexible printed circuit board with the heater wire, the resistance value of the heater wire can be measured for each individual unit, and if it differs from the target value, the heater wire can be short-circuited at the folded part to bring the resistance value closer to the target value. Alternatively, the resistance value of the heater wire can be brought closer to the target value by connecting the short-circuiting wire and the heater wire, or by cutting either the heater wire or the short-circuiting wire. This makes it possible to reduce the variation in the resistance value of the heater wire even if the shape accuracy of the length and thickness of the heater wire is low. Therefore, it is possible to reduce the variation in the heat generation amount of the heater, and the variation in the condensation removal ability of the lens unit can be reduced.

1 is a cross-sectional view of a lens unit according to an embodiment of the present invention. FIG. 2 is an exploded sectional perspective view of the lens unit of FIG. 1 . FIG. 3A is a plan view of a lens holder, and a plan view of a lens unit from which a first lens and an O-ring have been removed. FIG. FIG. 2 is a plan view of a flexible printed circuit board. FIG. FIG. 2 is a partially enlarged cross-sectional view of the lens unit. FIG. 11 is a plan view of a flexible printed circuit board on which a heater wire according to a first modified example is formed. FIG. 11 is a plan view of a flexible printed circuit board on which a heater wire and a short-circuiting wire are formed according to a second modified example. FIG. 11 is a plan view of a flexible printed circuit board on which a heater wire and a short-circuiting wire are formed according to a third modified example.

Below, an embodiment of a lens unit to which the present invention is applied is described with reference to the drawings.

(overall structure)
FIG. 1 is a cross-sectional view of a lens unit 1 according to an embodiment of the present invention. In FIG. 1, L is the optical axis of the lens unit 1. La is one side of the optical axis L direction, which is the object side (subject side) of the lens unit 1. Lb is the other side of the optical axis L direction, which is the image side of the lens unit 1. The lens unit 1 includes a plurality of lenses arranged in a row along the optical axis L, and a lens holder 2 that holds the plurality of lenses. The plurality of lenses include a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6. A light shielding plate L7 is disposed between the second lens L2 and the third lens L3, and an aperture L8 is disposed between the third lens L3 and the fourth lens L4.

Of the multiple lenses, the first lens L1, which is located closest to the object side La, and the fourth lens L4 are glass lenses. The fourth lens L4 is arranged inside the lens holder 2 while being fixed to a frame-shaped holder 3. The second lens L2, the third lens L3, the fifth lens L5, and the sixth lens L6 are plastic lenses. The sixth lens L6, which is located closest to the image side Lb, and the fifth lens L5 form a cemented lens L9. Note that the number and configuration of lenses held in the lens holder 2 are not limited to the above number and configuration.

The lens holder 2 is made of resin. The lens holder 2 includes a first housing portion 4 that holds a first lens L1, a second housing portion 5 that is disposed on the image side Lb of the first housing portion 4, and a lens case 6 that surrounds the outer periphery of the second housing portion 5. The lens case 6 extends from the outer periphery end of the first housing portion 4 to the image side Lb. The second housing portion 5 holds the second lens L2, the third lens L3, the fourth lens L4, and the cemented lens L9 (the fifth lens L5 and the sixth lens L6).

Figure 2 is an exploded cross-sectional perspective view of the lens unit 1 of Figure 1. Figure 3 is a perspective view of the lens holder 2. Figure 4(a) is a plan view of the lens holder 2, and Figure 4(b) is a plan view of the lens unit 1 with the first lens L1 and O-ring 7 removed. Figures 3 and 4 omit the illustration of the portion above the A-A position in Figure 1 (crimped portion 45). As shown in Figures 1 and 2, the first lens L1 is arranged in the lens holder 2 with the inner circumferential surface of the first housing portion 4 as a reference. Also, the second lens L2, third lens L3, fourth lens L4, and cemented lens L9 (fifth lens L5 and sixth lens L6) are arranged with the inner circumferential surface of the second housing portion 5 as a reference.

The first lens L1 is positioned in the direction of the optical axis L with reference to a lens seat surface 40 formed on the bottom of the first housing portion 4. As shown in Figures 1 and 3, the bottom of the first housing portion 4 includes an annular connecting portion 41 connected to the outer circumferential surface of the second housing portion 5, an annular restricting portion 42 protruding toward the object side La on the outer circumferential side of the annular connecting portion 41, and a peripheral wall portion 43 rising from the outer circumferential edge of the restricting portion 42 toward the object side La.

As shown in Figures 3 and 4, the restricting portion 42 has protrusions at multiple positions that protrude slightly from the annular end face 44 facing the object side La, and the tip surface of each protrusion forms the lens seat surface 40. In this embodiment, the lens seat surfaces 40 are provided at four positions at approximately angular intervals centered on the optical axis L. The outer peripheral portion of the first lens L1 abuts against the lens seat surface 40, and the first lens L1 is crimped and fixed by the crimping portion 45 provided at the tip of the peripheral wall portion 43. The gap between the first lens L1 and the first housing portion 4 is sealed by an O-ring 7.

As shown in Figures 1 and 2, the second housing portion 5 has a tube portion 51 connected to the annular connection portion 41 of the first housing portion 4, and a bottom portion 52 provided at the end of the tube portion 51 on the image side Lb extending in the optical axis L direction. The second lens L2, the third lens L3, the fourth lens L4, and the cemented lens L9 (the fifth lens L5 and the sixth lens L6) are positioned in the optical axis L direction based on a lens seat surface 50 (see Figures 3 and 4(a)) formed on the bottom portion 52 of the second housing portion 5.

The bottom 52 of the second storage section 5 has protrusions at multiple positions that protrude slightly from the annular bottom surface 53 facing the object side La, and the tip surface of each protrusion forms a lens seat surface 50. As shown in FIG. 4(a), in this embodiment, the lens seat surfaces 50 are provided at three positions at approximately angular intervals centered on the optical axis L. The second storage section 5 also has a recess 54 recessed to a predetermined depth on the image side Lb on the inner peripheral side of the annular bottom surface 53, and a circular opening 55 provided in the center of the recess 54.

The cemented lens L9 is positioned in the direction of the optical axis L by the outer periphery of the fifth lens L5 abutting against the lens seat surface 50. The sixth lens L6, which is disposed closest to the image side Lb, is housed inside the recess 54 but is not in contact with the inner surface of the recess 54 and is positioned in the direction of the optical axis L via the fifth lens L5.

The fourth lens L4 located on the object side La of the cemented lens L9 is held by the holder 3, and the holder 3 abuts against the outer periphery of the fifth lens L5 in the optical axis L direction. The outer periphery of the third lens L3 located on the object side La of the fourth lens L4 abuts against the outer periphery of the holder 3 in the optical axis L direction via the aperture L8. The outer periphery of the second lens L2 located on the object side La of the third lens L3 abuts against the outer periphery of the third lens L3 in the optical axis L direction via the light shielding plate L7. Therefore, the second lens L2, the third lens L3, and the fourth lens L4 are all positioned in the optical axis L direction with the lens seat surface 50 as a reference. The second lens L2 is fixed by crimping with the crimping portion 56 provided at the end of the object side La of the tube portion 51.

(First lens)
1 and 2, the first lens L1 includes an object-side lens surface 11 that is convex toward the object side La, an image-side lens surface 12 that is concave toward the object side La, an image-side flange surface 13 that surrounds the outer periphery of the image-side lens surface 12, and an annular step portion 14 that is recessed toward the object side La on the outer periphery of the image-side flange surface 13. The image-side flange surface 13 is an annular flat surface perpendicular to the optical axis L. An O-ring 7 is disposed on the annular step portion 14.

The image-side flange surface 13 is a light diffusing surface, and has fine irregularities (grain) formed over the entire surface. In this embodiment, a blackening film 15 is formed on the image-side flange surface 13. The blackening film 15 is formed, for example, by applying ink coating. The first lens L1 diffuses light with the fine irregularities (grain) and absorbs light with the ink coating, so that degradation of optical performance due to ghosting can be suppressed. The blackening film 15 is formed over substantially the entire image-side flange surface 13.

(Flexible Printed Circuit Board)
1 and 2, the lens unit 1 includes a flexible printed circuit board 8. The flexible printed circuit board 8 extends radially outward from between the first lens L1 and the second lens L2, is bent at a substantially right angle, and is passed through a through hole 46 formed in the first housing portion 4 of the lens holder 2, and is drawn out to the image side Lb of the lens holder 2.

Figure 5 is a plan view of the flexible printed circuit board 8. The flexible printed circuit board 8 has a power supply wiring 85 and a heater 9 arranged thereon. In this embodiment, a heat generating portion (heater 9) is arranged on the flexible printed circuit board 8. The heater 9 is made of a heater wire 90 (see Figure 7) formed on the surface of the flexible printed circuit board 8.

5, the flexible printed circuit board 8 includes an annular flat portion 81 along the image-side flange surface 13, an extension portion 82 extending linearly from the flat portion 81 toward the radially outward direction, and a protrusion portion 83 protruding radially outward from the flat portion 81 on both circumferential sides of the extension portion 82. The heater 9 is disposed on the flat portion 81 and the protrusion portion 83. In FIG. 5, X is an axis passing through the center P of the flat portion 81. The extension portion 82 extends in the direction of the axis X. The flexible printed circuit board 8 and the heater 9 are configured to be line-symmetrical with respect to the axis X. The heater 9 is disposed in a first region B1 on one side of the axis X and a second region B2 on the other side of the axis X. The first region B1 and the second region B2 are arc-shaped regions extending from the joint portion 86 to a position on the radially opposite side of the joint portion 86.

More specifically, the protrusion 83 includes a first protrusion 83A disposed on one circumferential side of the extension 82, and a second protrusion 83B disposed on the other circumferential side of the extension 82. The power supply wiring 85 includes a first power supply wiring 85A connected to one end of the heater wire 90, and a second power supply wiring 85B connected to the other end of the heater wire 90. One of the first power supply wiring 85A and the second power supply wiring 85B is connected to a positive electrode, and the other of the first power supply wiring 85A and the second power supply wiring 85B is connected to a negative electrode.

The planar portion 81 of the flexible printed circuit board 8 has a connecting portion 86 disposed radially inward of the extending portion 82, and an arc portion 87 extending circumferentially on both sides of the connecting portion 86. The arc portion 87 is connected to the extending portion 82 via the connecting portion 86. The protruding portions 83 protrude radially outward from the arc portion 87 on both sides of the connecting portion 86 in the circumferential direction.

The first power supply wiring 85A and the second power supply wiring 85B extend substantially parallel to each other while being electrically insulated at the extension portion 82 and the connecting portion 86. The first power supply wiring 85A and the second power supply wiring 85B have their radially inner ends connected to the heater 9.

The flexible printed circuit board 8 includes a flexible substrate 80A made of a resin film such as polyimide, and a heater wire 90 and a power supply wiring 85 are formed on the surface of the flexible substrate 80A using a conductive material such as Cu. An overcoat layer 80C that covers the heater wire 90 and the power supply wiring 85 is formed on the surface of the flexible substrate 80A. The overcoat layer 80C is formed on the flat portion 81 and the extension portion 82, but is not formed on the protrusion portion 83. Therefore, a portion of the heater wire 90 is not covered by the overcoat layer 80C.

The flexible printed circuit board 8 has a first notch 88 formed by cutting out a portion adjacent to the protrusion 83 in the circumferential direction in a linear manner toward the inside in the radial direction. More specifically, the first notch 88 is provided in two locations, between the first protrusion 83A and the extension 82, and between the second protrusion 83B and the extension 82. By providing the first notch 88, warping of the first protrusion 83A and the second protrusion 83B is suppressed. In addition, the heater wire 90 and the power supply wiring 85 are less likely to short-circuit.

The flexible printed circuit board 8 also includes a second notch 89 that is formed by cutting the inner peripheral edge of the connecting portion 86 in a straight line toward the outside in the radial direction. The second notch 89 is located approximately in the center of the extension portion 82 in the circumferential direction, and is disposed between the first power supply wiring 85A and the second power supply wiring 85B. By providing the second notch 89, warping of the connecting portion 86 is suppressed, and the first power supply wiring 85A and the second power supply wiring 85B are less likely to short-circuit.

In this embodiment, the first notch 88 and the second notch 89 are used as adhesive application grooves. When assembling the lens unit 1, the flexible printed circuit board 8 is fixed to the image-side flange surface 13 by the adhesive placed in the first notch 88 and the second notch 89.

When the flat portion 81 of the flexible printed circuit board 8 is fixed to the image side flange surface 13, the flat portion 81 is positioned so that the center of the image side flange surface 13 and the center of the flat portion 81 coincide with each other. The shape of the flat portion 81 is set to a shape that is unlikely to affect the optical performance of the lens unit 1. In this embodiment, the inner diameter D1 (see FIG. 2) of the flat portion 81 is a predetermined dimension (e.g., 0.4 mm) larger than the inner diameter D2 (see FIG. 2) of the image side flange surface 13. Therefore, there is little risk that the inner peripheral edge of the flat portion 81 will protrude into the inside of the image side lens surface 12, degrading the optical performance.

(Heater wire)
Fig. 6 is a partial enlarged view of the heater wire 90. Fig. 6(a) is a partial enlarged view of region D in Fig. 5, and Fig. 6(b) is a partial enlarged view of region E in Fig. 5. The heater wire 90 is a continuous conductor line, one end of which is connected to the first power supply wiring 85A and the other end of which is connected to the second power supply wiring 85B. The shape of the heater wire 90 disposed in the first region B1 on one side of the axis X will be described below. The heater wire 90 disposed in the second region B2 on the other side of the axis X has a shape that is line-symmetrical with respect to the heater wire 90 in the first region B1 with respect to the axis X.

6(a) and 6(b), the heater wire 90 arranged in the first region B1 is folded back at both ends of the first region B1 in the circumferential direction to the opposite side in the circumferential direction, and extends in a bellows-like manner in the radial direction. The heater wire 90 includes an arc-shaped heater wire 91 extending in the circumferential direction and a folded-back portion 92 arranged at the end of the heater wire 91 in the circumferential direction. The heater wires 91 are arranged at regular intervals in the radial direction. As shown in FIG. 6(a), the end of the innermost heater wire 91 on one side CCW in the circumferential direction is connected to the inner end of the second power supply wiring 85B in the radial direction. The end of the outermost heater wire 91 on the other side CW in the circumferential direction extends to the axis X and is connected to the heater wire 91 arranged on the outermost side of the second region B2.

The fold portion 92 includes a plurality of first fold portions 93 (see FIG. 6(a)) arranged at an end portion on one circumferential side CCW of the first region B1, a plurality of second fold portions 94 (see FIG. 6(b)) arranged at an end portion on the other circumferential side CW of the first region B1, and a plurality of third fold portions 95 arranged on the second protruding portion 83B.

Of the multiple heater wires 91, some of the heater wires 91 arranged radially inward extend to the connecting portion 86 and are connected to the first folded portion 93. The first folded portion 93 is arranged in a row in the radial direction at a position adjacent to the second power supply wiring 85B in the circumferential direction. Of the multiple heater wires 91, the heater wires 91 arranged radially outward from the heater wires 91 connected to the first folded portion 93 are connected to the third folded portion 95 extending radially outward on the other circumferential side CW of the first folded portion 93. The multiple third folded portions 95 are arranged in a row in the circumferential direction at the second protruding portion 83B. The second folded portion 94 is arranged in a row in the radial direction at a position radially opposite to the connecting portion 86. All of the heater wires 91 except for the heater wires 91 on the outermost side are connected to the second folded portion 94.

Two heater wires 91 extending approximately parallel to each other are connected to the first folded portion 93 and the second folded portion 94, respectively. As shown in the partially enlarged view of FIG. 6(b), the line width W1 of the second folded portion 94 is larger than the line width W0 of the heater wire 91. The line width of the first folded portion 93 is equal to the line width W1 of the second folded portion 94 and is larger than the line width W0 of the heater wire 91. Therefore, the heater wire 90 is less likely to break at the folded position. In this embodiment, the line width W0 of the heater wire 91 is 30 μm, and the line width W1 of the first folded portion 93 and the second folded portion 94 is 120 μm.

As shown in FIG. 6(a), the third folded portion 95 includes a first portion 951 connected to the two heater wires 91, and a second portion 952 extending radially outward from the tip of the first portion 951. The third folded portion 95 has different line widths in the first portion 951 and the second portion 952, and the line width W3 of the second portion 952 is larger than the line width W2 of the first portion 951. In this embodiment, the line width W2 of the first portion 951 is 120 μm, and the line width W3 of the second portion 952 is 160 μm. In addition, the gap between adjacent first portions 951 is 100 μm, and the gap between adjacent second portions 952 is 50 μm.

When manufacturing the lens unit 1, after forming the heater wire 90 on the flexible printed circuit board 8, the resistance value of the heater wire 90 is measured for each individual unit, and if the resistance value of the heater wire 90 differs from the target value, the resistance value of the heater wire 90 is adjusted by shorting the folded portion 92. For this reason, the heater wire 90 is formed in a shape with multiple folded portions 92. The multiple folded portions 92 are arranged in a row. Therefore, by attaching a short-circuit conductive material 96 between adjacent folded portions 92, the heater wire 90 can be shorted at the position of the folded portion 92 to adjust the resistance value.

A part of the folded portion 92 has an exposed portion 97 exposed from the overcoat layer 80C. Therefore, the heater wire 90 can be short-circuited by attaching a short-circuit conductive material 96 to the exposed portion 97. As shown in Figs. 5 and 6(a), the first protruding portion 83A and the second protruding portion 83B are not covered by the overcoat layer 80C, so the second portion 952 of the third folded portion 95 has an exposed portion 97. Therefore, as shown in Fig. 6(a), the heater wire 90 can be short-circuited by attaching a short-circuit conductive material 96 between adjacent exposed portions 97.

In this embodiment, the third folded portion 95 extends in the radial direction, and the exposed portions 97 are arranged in a row along the outer periphery of the flexible printed circuit board 8. Therefore, it is easy to attach the short-circuit conductive material 96 between adjacent exposed portions 97. Also, as described above, in the third folded portion 95, the line width W3 of the second portion 952 which is the exposed portion 97 is large, and the gap between adjacent exposed portions 97 is small. As described above, in this embodiment, the gap between adjacent exposed portions 97 is 50 μm. Therefore, there is little risk that the heater wire 90 will not be able to be short-circuited due to misalignment of the short-circuit conductive material 96 or an insufficient amount of the short-circuit conductive material 96.

(Positioning of the First Lens in the Direction of the Optical Axis L)
Fig. 7 is a partially enlarged cross-sectional view of the lens unit 1, cut at the position CC in Fig. 4(b). As shown in Fig. 7, the lens holder 2 has a restricting portion 42 protruding from the bottom surface of the first housing portion 4 toward the object side La, and the image side flange surface 13 of the first lens L1 has an outer peripheral region 13A that abuts against a lens seat surface 40 provided at the tip of the restricting portion 42. The image side flange surface 13 also has an inner peripheral region 13B located on the inner peripheral side of the outer peripheral region 13A, and the flat portion 81 of the flexible printed circuit board 8 is disposed in the inner peripheral region 13B.

4B and 7, when the first lens L1 is attached to the first housing portion 4, the flat portion 81 arranged in the inner circumferential region 13B of the image side flange surface 13 is arranged on the inner circumferential side of the restricting portion 42. Therefore, the flat portion 81 does not interfere with the restricting portion 42, and the flexible printed circuit board 8 is not sandwiched between the first lens L1 and the lens holder 2. In this embodiment, the position of the first lens L1 in the optical axis L direction is determined by the direct abutment of the outer circumferential region 13A of the image side flange surface 13 and the lens seat surface 40.

As shown in FIG. 7, the flat portion 81 of the flexible printed circuit board 8 extends radially outward beyond the crimped portion 56 that secures the outer peripheral edge of the second lens L2. In this embodiment, the gap S in the optical axis L direction between the crimped portion 56 and the inner peripheral region 13B of the image-side flange surface 13 is larger than the thickness of the flexible printed circuit board 8. Therefore, the flat portion 81 does not interfere with the crimped portion 56, and the flexible printed circuit board 8 is not sandwiched between the first lens L1 and the crimped portion 56.

(Counterbore part)
As shown in Figs. 2, 3, and 4, the first housing 4 includes a recessed portion 47 that is recessed radially outward from the inner peripheral edge of the restricting portion 42. As shown in Fig. 4B, the extension portion 82 and the protrusion portion 83 of the flexible printed circuit board 8 are disposed in the recessed portion 47. As shown in Fig. 2, the extension portion 82 is bent toward the image side Lb midway as it extends radially outward, and is inserted into the slit-shaped through hole 46 that opens on the bottom surface of the recessed portion 47. Therefore, the extension portion 82 and the protrusion portion 83 do not interfere with the restricting portion 42. The extension portion 82 may include a reinforcing plate 80B fixed to the flexible substrate 80A. When the reinforcing plate 80B is provided, the reinforcing plate 80B is disposed in the through hole 46.

As shown in Figures 1 and 2, the through hole 46 penetrates the bottom of the first housing portion 4 in the optical axis L direction and communicates with the gap between the tube portion 51 of the second housing portion 5 and the lens case 6. The inner peripheral surface of the lens case 6 is recessed in a shape that follows the radially outer edge of the through hole 46. The extension portion 82 inserted into the through hole 46 passes through the gap between the inner peripheral surface of the lens case 6 and the outer peripheral surface of the tube portion 51 and is drawn out to the image side Lb of the lens holder 2.

In this embodiment, the extension portion 82 is not fixed to the through hole 46, but it is also possible to place an adhesive in the through hole 46 and fix the extension portion 82 to the through hole 46 with the adhesive. In this case, by forming an unevenness on the inner peripheral surface of the through hole 46, the adhesion area can be increased and the fixing strength of the extension portion 82 can be increased.

The restricting portion 42 has an outer edge portion 48 that extends in the circumferential direction radially outside the countersunk portion 47. The outer edge portion 48 is connected to the lens seating surfaces 40 provided on both sides of the countersunk portion 47 in the circumferential direction. Therefore, in this embodiment, the restricting portion 42 is annular as a whole and faces the outer peripheral edge of the first lens L1 all around. Therefore, the O-ring 7 arranged on the outer peripheral edge of the first lens L1 is supported by the restricting portion 42 all around, so that the O-ring 7 does not fall inside the countersunk portion 47, which reduces the sealing performance.

(Main effects of this embodiment)
As described above, the lens unit 1 of this embodiment includes the first lens L1 located closest to the object side La, the second lens L2 disposed on the image side Lb relative to the first lens L1, a lens holder including a first housing portion 4 for housing the first lens L1 and a second housing portion 5 for housing the second lens L2, and a flexible printed circuit board 8 including a heater. The first lens L1 includes an object side lens surface 11, an image side lens surface 12, and an image side flange surface 13 surrounding the image side lens surface 12. The flexible printed circuit board 8 includes a flat portion 81 along the image side flange surface 13 and an extension portion 82 extending radially outward. A power supply wiring 85 is disposed in the extension portion 82, and a heater wire 90 connected to the power supply wiring 85 is disposed in the flat portion 81. The heater wire 90 includes a plurality of third folded portions 95 (folded portions).

In this embodiment, the first lens L1 can be heated by the heater wire 90 arranged on the flexible printed circuit board 8, so that it is possible to prevent condensation inside the lens unit 1 and deterioration of optical performance. In addition, the heater 9 arranged inside the lens unit 1 can be adjusted by measuring the resistance value of the heater wire 90 for each individual unit after manufacturing, and if it differs from the target value, the heater wire 90 can be short-circuited at the third folded portion 95 to bring the resistance value closer to the target value. Therefore, even if the shape accuracy of the length and thickness of the heater wire 90 is low, the variation in the resistance value of the heater wire 90 can be reduced. Therefore, there is little variation in the heat generation amount of the heater 9, and there is little variation in the condensation removal ability of the lens unit 1.

For example, if the measured resistance value of the heater wire 90 deviates from the target value, a short-circuit conductive material 96 is attached to a position that contacts both of the adjacent third folded portions 95 to short-circuit the heater wire 90. A conductive paste or conductive adhesive can be used as the short-circuit conductive material 96. Therefore, the heater wire 90 can be easily short-circuited, and the resistance value of the heater wire 90 can be easily adjusted.

If the measured resistance value of the heater wire 90 does not deviate from the target value, there is no need to short-circuit the heater wire 90. Therefore, in this case, the flexible printed circuit board 8 can be used without attaching the short-circuit conductive material 96 to the third folded portion 95.

In this embodiment, the multiple third folds 95 are aligned along the edge of the protruding portion 83 of the flexible printed circuit board 8, making it easy to attach the short-circuit conductive material 96 to the desired position. Even if the short-circuit conductive material 96 protrudes from between the third folds 95, there is little risk that the short-circuit conductive material 96 will adhere to a location other than the area to be short-circuited. Therefore, the resistance value of the heater wire 90 can be easily and accurately adjusted.

In this embodiment, the flexible printed circuit board 8 has a protruding portion 83 that protrudes radially outward from the flat portion 81, and the third folded portion 95 is disposed on the protruding portion 83. Therefore, since the third folded portion 95 can be disposed radially outward, components such as the second lens L2 disposed on the image side of the first lens L1 and the lens holder 2 having the crimping portion 56 that crimps and fixes the outer periphery of the second lens L2 are unlikely to interfere with the third folded portion 95. Therefore, there is little risk that the third folded portion 95 will be pinched and crushed between the first lens L1 and other components, and therefore there is little risk that the third folded portion 95 will short-circuit even though the short-circuit conductive material 96 is not attached. In addition, when the short-circuit conductive material 96 is attached, there is little risk that the short-circuit conductive material 96 will be crushed and spread to an unintended range, causing the heater wire 90 to short-circuit at an unintended position. Therefore, the resistance value of the heater wire 90 can be adjusted with high precision.

In the flexible printed circuit board 8 of this embodiment, the flat portion 81 on which the heater 9 is arranged is annular, and the first power supply wiring 85A and the second power supply wiring 85B extend radially from the extension portion 82 to the flat portion 81. The heater wire 90 is connected to the radially inner ends of the first power supply wiring 85A and the second power supply wiring 85B. In this way, when one heater wire 90 is arranged on the flat portion 81, if the start point and end point of the heater wire 90 (the parts connected to the first power supply wiring 85A and the second power supply wiring 85B) are arranged on the radially inner side, it is easy to arrange the third folded portion 95 on the radially outer side. Therefore, it is easy to short-circuit the third folded portion 95.

In this embodiment, the flexible printed circuit board 8 includes an overcoat layer 80C that covers the power supply wiring 85 and the heater wire 90, and can therefore protect the heater wire 90. The overcoat layer 80C is formed on the flat portion 81 and the extending portion 82, but is not formed on the protruding portion 83. Therefore, the third folded portion 95 disposed on the protruding portion 83 includes an exposed portion 97 that is exposed from the overcoat layer 80C, and therefore the heater wire 90 can be short-circuited simply by attaching the short-circuit conductive material 96 to the exposed portion 97.

In this embodiment of the heater wire 90, the line width of the folded portion 92 is larger than the line width W0 of the thin heater wire 91. That is, the line width W1 of the first folded portion 93 and the second folded portion 94, and the line widths W2 and W3 of the third folded portion 95 are all larger than the line width W0 of the thin heater wire 91. Therefore, there is little risk of the heater wire 90 breaking at the folded position.

In this embodiment, the third folded portion 95 of the heater wire 90 includes a first portion 951 that is connected to the heater wire and a second portion 952 that protrudes from the first portion 951, and the line width W3 of the second portion 952 is greater than the line width W2 of the first portion 951. Therefore, the third folded portion 95 has a large line width at the tip side, making it easy to short-circuit. In addition, the gap between adjacent third folded portions 95 is narrow, so there is little risk of not being able to short-circuit due to misalignment or insufficient amount of short-circuit conductive material 96.

The configuration in which the resistance value can be adjusted by short-circuiting the heater wire 90 is not limited to the above embodiment. For example, the configuration of modified example 1-3 described below can be adopted.

(Variation 1)
8 is a plan view of a flexible printed circuit board 8 on which a heater wire 190 of the first modification is formed. The heater 9 of the first modification includes a heater wire 190 disposed on the flat portion 81 of the flexible printed circuit board 8. The heater wire 190 includes a plurality of heater wire portions 190A arranged in the circumferential direction. Each heater wire portion 190A includes an arc-shaped heater wire 191 extending in the circumferential direction, a folded portion 192 connected to an end of the heater wire 191 in the circumferential direction, and a straight portion 193 extending in the radial direction. The plurality of heater wires 191 arranged at regular intervals in the radial direction are folded back to the opposite side in the circumferential direction by the folded portion 192, and extend in the radial direction in an accordion-like manner. The straight portion 193 connects the heater wire portions 190A adjacent to each other in the circumferential direction.

In the flexible printed circuit board 8 of the first modified example, an overcoat layer is not provided in the area where the heater wire 190 is arranged, so the heater wire 190 is exposed. Therefore, as shown in FIG. 8, by attaching a short-circuit conductive material 196 to the folded portion 192 of each heater wire portion 190A, it is possible to short-circuit adjacent heater wire portions 190A in the circumferential direction. In the example shown in FIG. 8, two places are short-circuited, but the position and number of short circuits can be selected appropriately depending on the resistance value.

As shown in FIG. 8, in the first modified example, the first power supply wiring 85A and the second power supply wiring 85B extend substantially parallel to each other while being electrically insulated from each other at the extension portion 82 of the flexible printed circuit board 8, and extend to opposite sides in the circumferential direction at the connection portion 86. The first power supply wiring 85A extending to one side in the circumferential direction is connected to one end of the heater wire 190. The second power supply wiring 85B extending to the other side in the circumferential direction is connected to the other end of the heater wire 190.

The heater wire 190 of the first modification can heat the first lens L1 in the same manner as the above embodiment, and therefore can suppress the deterioration of optical performance due to condensation inside the lens unit 1. The heater wire 190 also includes a folded portion 192. Therefore, after manufacturing, the resistance value of the heater wire 190 is measured for each individual, and if it differs from the target value, the heater wire 190 can be short-circuited at the position of the folded portion 192 to bring the resistance value closer to the target value. This provides a heater 9 including a short-circuit conductive material 196 that short-circuits the heater wire 190. Alternatively, if the resistance value does not need to be adjusted, the heater wire 190 can be used as the heater 9 without being short-circuited. Therefore, even if the shape accuracy of the length and thickness of the heater wire 190 is low, the variation in the resistance value of the heater wire 190 can be reduced. Therefore, the variation in the heat generation amount of the heater 9 can be reduced, and the variation in the dew removal ability of the lens unit 1 can be reduced.

(Variation 2)
9 is a plan view of the flexible printed circuit board 8 on which a heater wire 290 and a short-circuiting wire 200 of the modified example 2 are formed. The heater 9 of the modified example 2 includes a heater wire 290 and a short-circuiting wire 200 disposed on a flat portion 81 of the flexible printed circuit board 8. The heater wire 290 has substantially the same shape as the heater wire 190 of the modified example 1, and includes a thin heater wire 291 extending in the circumferential direction, a folded-back portion 292, and a straight portion 293 extending in the radial direction. One end of the heater wire 290 is connected to the first power supply wiring 85A, and the other end is connected to the second power supply wiring 85B.

The short-circuiting wiring 200 extends circumferentially along the outer periphery of the flat portion 81. The short-circuiting wiring 200 is disposed radially outside the heater wire 290 and is spaced apart from the heater wire 290. The short-circuiting wiring 200 is an electrically independent dummy wiring and is not electrically connected to the first power supply wiring 85A and the second power supply wiring 85B.

In the flexible printed circuit board 8 of the second modification, since no overcoat layer is provided in the arrangement area of the heater wire 290 and the short-circuiting wiring 200, the heater wire 290 and the short-circuiting wiring 200 are exposed. Therefore, as shown in FIG. 9, the short-circuiting wiring 200 and the heater wire 290 can be connected at two points by the short-circuiting conductive material 296 attached to the short-circuiting wiring 200, thereby short-circuiting the heater wire 290. The position of the short-circuiting may be appropriately selected according to the resistance value. In this embodiment, the interval W4 between the short-circuiting wiring 200 and the heater wire 291 located at the outermost radial side is smaller than the interval W5 between the heater wires 291 adjacent in the radial direction. Therefore, the short-circuiting wiring 200 and the heater wire 290 can be easily short-circuited, and there is little risk of the short-circuiting being impossible due to a shift in the attachment position of the short-circuiting conductive material 296 or a variation in the amount of attachment.

The heater wire 290 of the second modification can heat the first lens L1 in the same manner as in the above embodiment, so that it is possible to suppress the deterioration of optical performance due to condensation inside the lens unit 1. In addition, in the second modification, the heater wire 290 and the short-circuiting wiring 200 are arranged on the flat portion 81 of the flexible printed circuit board 8. Therefore, the resistance value of the heater wire 290 is measured for each individual after manufacturing, and if it differs from the target value, the short-circuiting wiring 200 and the heater wire 290 are connected to short-circuit the heater wire 290, so that the resistance value approaches the target value. This makes it possible to reduce the variation in the resistance value of the heater wire 290 even if the shape accuracy of the length and thickness of the heater wire 290 is low. Therefore, it is possible to reduce the variation in the heat generation amount of the heater 9, and the variation in the condensation removal ability of the lens unit 1 can be reduced.

In the embodiment shown in FIG. 9, the short-circuiting wiring 200 is not connected to the first power supply wiring 85A and the second power supply wiring 85B, but the short-circuiting wiring 200 may be connected to the first power supply wiring 85A or the second power supply wiring 85B. This makes it possible to short-circuit the heater wire 290 by simply placing the short-circuiting conductive material 296 in one location.

(Variation 3)
10 is a plan view of a flexible printed circuit board 8 on which a heater wire 390 and a short-circuiting wire 300 of the third modification are formed. The heater 9 of the third modification includes a heater wire 390 and a short-circuiting wire 300 disposed on a flat portion 81 of the flexible printed circuit board 8. The heater wire 390 has substantially the same shape as the heater wire 190 of the first modification, and includes a thin heater wire 391 extending in the circumferential direction, a folded portion 392, and a straight portion 393. The thin heater wire 391 and the folded portion 392 are connected in a bellows shape. One end of the heater wire 390 is connected to the first power supply wiring 85A, and the other end is connected to the second power supply wiring 85B.

In the third modification, the heater wire 391, the folded portion 392, and the straight portion 393 constitute the heater wire portion 390A, and the heater wire 390 has a plurality of heater wire portions 390A arranged in the circumferential direction. The short-circuiting wires 300 extend in the circumferential direction along the outer periphery of the flat portion 81, and are disposed radially outward of the heater wire 390. The short-circuiting wires 300 are disposed in six locations spaced apart in the circumferential direction. Each short-circuiting wire 300 connects adjacent heater wire portions 390A. In other words, the heater wire 390 is short-circuited in six locations by the six short-circuiting wires 300.

The heater wire 390 of the third modified example can heat the first lens L1 in the same manner as the above embodiment, and therefore can prevent condensation inside the lens unit 1 from deteriorating the optical performance. In addition, the resistance value of the heater wire 390 is measured for each individual unit after manufacture, and if the measurement result differs from the target value, either the short-circuiting wiring 300 or the heater wire portion 390A can be cut by a laser to bring the resistance value of the heater wire 390 closer to the target value. After the resistance value is adjusted, the heater 9 has a cut portion cut by a laser in either the short-circuiting wiring 300 or the heater wire 390 short-circuited by the short-circuiting wiring 300.

The cutting position Q1 when cutting the short-circuit wiring 300 and the cutting position Q2 when cutting the heater wire portion 390A can be, for example, the positions shown in FIG. 10. If the cutting position Q2 of the heater wire portion 390A is set to the innermost heater wire 391, it is easy to cut at the correct position and there is little risk of accidentally cutting other portions. In addition, since the short-circuit wiring 300 extends along the outer periphery of the flat portion 81, it is easy to cut at the correct position and there is little risk of accidentally cutting other portions.

In the third modification, as described above, the heater wire 390 is short-circuited in advance by the short-circuiting wiring 300, and the resistance value can be adjusted by cutting the heater wire 390 or the short-circuiting wiring 300. Therefore, even if the shape precision of the length and thickness of the heater wire 390 is low, the variation in the resistance value of the heater wire 390 can be reduced by adjusting the resistance value. This reduces the variation in the heat generation amount of the heater 9, and reduces the variation in the condensation removal ability of the lens unit 1.

(Other Modifications)
A transparent conductive film that functions as a heater may be provided on the image-side lens surface 12 of the first lens L1, and power may be supplied to the transparent conductive film from an electrode formed on the flexible printed circuit board. In this way, the first lens L1 can be heated by the heater wire 90 and the transparent conductive film, thereby improving the dew condensation removal capability.

1...lens unit, 2...lens holder, 3...holder, 4...first housing section, 5...second housing section, 6...lens case, 7...O-ring, 8...flexible printed circuit board, 9...heater, 11...object side lens surface, 12...image side lens surface, 13...image side flange surface, 13A...outer circumferential region, 13B...inner circumferential region, 14...annular step portion, 15...blackened film, 40...lens seating surface, 41...annular connecting portion, 42...regulating portion, 43...peripheral wall portion, 44...annular end surface, 45...crimping portion, 46...through hole, 47...countersunk portion, 48...outer edge portion, 50...lens seating surface, 51...tubular portion, 52...bottom portion, 53...annular bottom surface, 54...recess, 55...opening, 56...crimp portion, 80A...flexible substrate, 80B...reinforcing plate, 80C...overcoat layer, 81...flat portion, 82...extending portion, 83...projecting portion, 83A...first projecting portion, 83B...second projecting portion, 85...power supply wiring, 85A...first power supply wiring, 85B...second power supply wiring, 86...connecting portion, 87...arc portion, 88...first notch portion, 89...second notch portion, 90...heater wire, 91...thin heater wire, 92...folded portion, 93...first folded portion, 94...second folded portion, 95...third folded portion, 96...short-circuit conductive material, 97...exposed portion, 190, 290, 390...heater wire, 190A, 390A...heater wire portion, 191, 291, 391
. . heater thin wire, 192, 292, 392... folded portion, 193, 293, 393... straight portion, 196, 296... short-circuit conductive material, 200, 300... short-circuit wiring, 951... first portion, 952... second portion, B1... first region, B2... second region, CCW... one side in the circumferential direction, CW... other side in the circumferential direction, L... optical axis, La... object side, Lb... image side, L1... first lens, L2... third lens, L3... third lens, L4... fourth lens, L5... fifth lens, L6... sixth lens, L7... light shielding plate, L8... aperture, L9... cemented lens, P... center of flat portion, Q1, Q2... cutting position, S... gap

Claims (7)

a first lens located closest to the object;
A second lens disposed on an image side relative to the first lens;
a lens holder including a first housing portion for housing the first lens and a second housing portion for housing the second lens;
A flexible printed circuit board having a heater,
the first lens comprises an object-side lens surface, an image-side lens surface, and an image-side flange surface surrounding the image-side lens surface;
the flexible printed circuit board includes a flat portion along the image side flange surface and an extension portion extending radially outward,
A power supply line is disposed on the extension portion,
a heater wire connected to the power supply wiring is disposed on the planar portion;
The heater wire has a plurality of folded portions ,
The flexible printed circuit board includes a protruding portion protruding radially outward from the planar portion,
The lens unit, wherein the folded portion is disposed on the protruding portion . The lens unit according to claim 1, characterized in that the multiple folded portions are aligned along the edge of the flexible printed circuit board. A short-circuit conductive material is attached to the folded portion,
3. The lens unit according to claim 1, wherein the heater wire is short-circuited by the short-circuit conductive material. The planar portion is annular,
the power supply wiring extends in a radial direction from the extension portion to the planar portion,
4. The lens unit according to claim 1, wherein the heater wire is connected to an end portion of the power supply wiring on an inner side in a radial direction. the flexible printed circuit board includes an overcoat layer that covers the power supply wiring and the heater wire;
The lens unit according to claim 1 , wherein the folded portion has an exposed portion that is exposed from the overcoat layer. the heater wire includes a thin heater wire connected to the folded-back portion,
6. The lens unit according to claim 1, wherein the folded portion has a line width larger than a line width of the heater thin wire. the folded portion includes a first portion connected to the heater wire and a second portion protruding from the first portion,
The lens unit according to claim 6 , wherein the line width of the second portion is greater than the line width of the first portion.

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