JP2007233046A - Camera lens unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a camera lens unit capable of obtaining stable image forming characteristic as a lens for camera. <P>SOLUTION: The camera lens unit is equipped with: an optical lens system including at least one optical lens; a variable focus type liquid crystal lens, holding a liquid crystal layer between two rectangular transparent substrates; a holding member where the liquid crystal lens is fixedly arranged; and a lens frame, provided internally with the optical lens system and the holding member, in such a state that the centers of the optical axes of the optical lens and the liquid crystal lens are aligned with each other. The holding member has a butting part abutting against the inner wall surface of the lens frame, when the holding member is assembled in the lens frame, and the butting part of the holding member is made to abut against the inner wall surface of the lens frame, whereby the center of the optical axis of the liquid crystal lens is aligned with the center axis of the optical lens. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a camera lens unit in which a variable focus type liquid crystal lens is incorporated in a lens frame.

  Conventionally, as a focusing mechanism for changing the focal length or focal position of a camera, a method of focusing by combining two or more lenses and changing the positional relationship has been widely used. However, this method requires a lens driving mechanism, and thus has a drawback that the mechanism is complicated and a lens driving motor requires a relatively large amount of electric power. In addition, there is a drawback that the impact resistance is generally low. Thus, as a focusing mechanism that does not require a lens driving mechanism, a method of focusing by changing the refractive index of the liquid crystal lens has been proposed (for example, see Patent Document 1).

  Here, in order to obtain a stable imaging characteristic as a lens for a camera, it is necessary to match the optical axes of the lenses to be combined with high accuracy, and this is the same when combining liquid crystal lenses.

  Thus, a method of combining the optical axes of liquid crystal lenses to match the optical axes of the lenses and the structure of the lens unit have been proposed (see, for example, Patent Document 2 and Patent Document 3). All of these adopt a configuration in which the transparent substrate constituting the liquid crystal lens is cut into a circular shape and incorporated into the lens frame. The optical substrate is positioned by fitting the outer shape of the transparent substrate and the inner wall surface of the lens frame, and the light The method of aligning the axes is used. By adopting this conventional configuration, it is possible to easily align the optical axis between the liquid crystal lens and another optical component.

  On the other hand, in the general liquid crystal panel manufacturing process, it is most reasonable to make the panel outer shape a quadrangle because it is the most mass-productive and rational. After a cut line is formed with a so-called scribe cutter, a method of cleaving with a break bar from the cut line and a method of cutting four sides of the transparent substrate into a predetermined size with a grindstone called a dicing method are used.

  The external shape processing accuracy of the liquid crystal panel is about ± 100 to ± 200 μm in the scribe break method, and is about ± 10 to ± 100 μm in the dicing method.

Japanese Patent No. 3047082 (page 3-8, FIG. 1-14) JP-A-2-271317 (page 2-5, Fig. 1-4) Japanese Unexamined Patent Publication No. 2000-347154 (page 3-8, FIG. 1-12)

  However, in the conventional techniques shown in Patent Document 2 and Patent Document 3, the transparent substrate must be precisely cut into a circle. In manufacturing a liquid crystal panel, processing the outer shape of the transparent substrate into a circle leads to deterioration of cost, yield, and reliability. This is especially true when high-precision outer shape processing is required to fit a lens frame and a circular liquid crystal lens manufactured by a general liquid crystal panel manufacturing process.

  Furthermore, in the method disclosed in Patent Document 2, it is necessary to individually inject liquid crystal after the transparent substrate is incorporated into the lens frame, leading to a reduction in productivity.

  On the other hand, if the liquid crystal lens has a square shape (rectangular shape) and is produced by a method similar to a conventional liquid crystal panel manufacturing process, the cost, yield, reliability, and the like are disclosed in Patent Document 2. 3 can be improved as compared with the embodiment shown in FIG. However, on the other hand, the poor processing accuracy of the transparent substrate corresponds to the dimensional accuracy from the optical axis of the liquid crystal lens to the external side, so even if the liquid crystal lens is positioned on the lens frame by fitting the external shape, the dimensions There is a problem that the accuracy becomes the amount of deviation from the optical axis, and stable imaging characteristics cannot be obtained as a lens for a camera.

  Also, even if positioning is performed using a jig, in a small camera lens unit, it is necessary to position and fix so that the center axis of the cylindrical lens frame and the optical axis of the rectangular liquid crystal lens are aligned. There is a problem that workability is extremely poor. In particular, when the liquid crystal lens has a structure sandwiched between optical lenses to be combined in the lens frame, it is difficult to position the liquid crystal lens.

  Therefore, the present invention solves the above-mentioned problems, makes the outer shape of the liquid crystal lens a quadrangular shape (rectangular shape), and creates it by the same method as the manufacturing process of a liquid crystal panel that is generally performed in the past. While improving the reliability, etc., the liquid crystal lens can be easily positioned with high precision on the lens frame and matched with the optical axis of the other lens to be combined with high precision to obtain stable imaging characteristics as a camera lens. An object of the present invention is to provide a camera lens unit.

  In order to achieve the above object, the camera lens unit of the present invention basically adopts the following configuration.

  The camera lens unit of the present invention includes an optical lens system including at least one optical lens, a variable focus type liquid crystal lens having a liquid crystal layer sandwiched between two rectangular transparent substrates, and the liquid crystal lens fixed thereto. The holding member, and a lens frame that interpolates the optical lens system and the holding member so that the optical axes of the optical lens and the liquid crystal lens coincide with each other, and the holding member incorporates the holding member into the lens frame. Sometimes the abutting portion that abuts against the inner wall surface of the lens frame, and the abutting portion of the holding member abuts against the inner wall surface of the lens frame, so that the center of the optical axis of the liquid crystal lens is the center of the optical lens. It is characterized by being coincident with the axis.

  The camera lens unit of the present invention is characterized in that the shape of the abutting portion and the shape of the inner wall surface of the lens frame are similar arc shapes.

  The camera lens unit of the present invention is characterized in that the holding member described above is inserted into the lens frame from a direction orthogonal to the optical axis center of the optical lens.

  According to the present invention, a liquid crystal lens having a rectangular shape can be incorporated into a lens frame via the holding member by fixing the liquid crystal lens at a predetermined position of the holding member that is positioned by abutting against the cylindrical inner wall of the lens frame. Therefore, the central axis of the lens frame and the optical axis of the liquid crystal lens can be aligned with the lens frame having the cylindrical inner wall much more easily than when the liquid crystal lens is positioned and fixed alone. In other words, the liquid crystal lens has a square outer shape and is manufactured in the same way as the conventional liquid crystal panel manufacturing process, making it easy to improve the cost, yield, reliability, etc. The optical axis of the lens can be matched with the optical axis of another lens to be combined with high accuracy, and stable imaging characteristics can be obtained as a lens for a camera.

  Hereinafter, a preferred embodiment of a camera lens unit according to the present invention will be described in detail with reference to FIGS. 1 to 6.

  First, the configuration of the camera lens unit of the present invention will be described. FIG. 1 is an exploded view for explaining the overall structure of the camera lens unit of the present invention. FIG. 2 is a cross-sectional view illustrating the overall configuration of the camera lens unit of the present invention.

  Reference numeral 2 in FIG. 1 denotes an optical lens system including first to third optical lenses 21 to 23 as a plurality of optical lenses. Reference numeral 3 denotes a variable focus liquid crystal lens having a liquid crystal layer sandwiched between transparent substrates. Reference numeral 4 denotes a bottomed cylindrical lens frame for housing the plurality of optical lens systems 2 and the liquid crystal lens 3, and reference numeral 5 denotes a holding member for fixing the liquid crystal lens 3 and incorporating it into the lens frame 4.

  As shown in FIG. 2, the lens system has a first optical lens 21 through which light enters from a window 41 provided in the lens frame 4, and light that has passed through the first optical lens 21 enters. The liquid crystal lens 3 includes a second optical lens 22 on which light that has passed through the liquid crystal lens 3 enters, and a third optical lens 23 on which light that has passed through the second optical lens 22 enters. The optical lens system 2 is housed in the cylindrical inner wall of the lens frame 4 so that the center axis 42 of the lens frame 4 coincides with the center of the optical axis of each lens.

  The optical lens system 2 shown in this drawing (see FIG. 1) is a plurality of lens systems in which a plastic such as polycarbonate or PMMA, or glass is molded in a mold, and each lens has a cylindrical outer shape. ing. In this embodiment, an example is shown in which the optical lens system 2 includes three lenses (a first optical lens 21, a second optical lens 22, and a third optical lens 23). It is precisely molded to be concentric with the center of the optical axis of the lens. At the same time, the outer diameter of the lens frame 4 is molded with high accuracy so that the outer diameter of the lens frame 4 is positioned against the step provided on the cylindrical inner wall 43. The optical axis centers of the three first to third optical lenses 21 to 23 coincide with the central axis 42 by being incorporated in the cylindrical inner wall 43 of the lens frame 4.

  The lens frame 4 is a plastic molded product such as a bottomed cylindrical polycarbonate or PMMA, and the inner side of the bottom is a stepped cylindrical inner wall 43 formed in accordance with the inner diameter of each lens and a central axis 42. Abutment surface 44, which is a vertical surface, a window 41 for taking in external light into the lens frame 4 at the center of the abutment surface 44, and a through hole 45 into which the liquid crystal lens 3 is inserted. .

  The first optical lens 21 is fitted to the bottom of the lens frame 4 from the rear in the optical axis direction, and the peripheral portion of the front surface 211 (subject side) of the first optical lens 21 hits the abutting surface 44. In the applied state, the side surface of the first optical lens 21 and the cylindrical inner wall 43 of the lens frame 4 are bonded by, for example, a UV curable adhesive.

  The liquid crystal lens 3 is positioned and fixed at a predetermined position of the holding member 5 with an adhesive or the like, and is inserted into the lens frame 4 through a through hole 45 provided in a side portion of the lens frame 4 together with the holding member 5. . With the front side (subject side) surface of the liquid crystal lens 3 abutted against the peripheral portion of the rear surface 212 of the first optical lens 21, the rear surface 212 of the first optical lens 21 and the liquid crystal An interval in the effective area with the lens 3 is a predetermined interval.

  Here, the positioning of the liquid crystal lens 3 in the direction perpendicular to the optical axis is performed by providing the holding member 5 to which the liquid crystal lens 3 is fixed with an abutting portion 53 that contacts the cylindrical inner wall 43 of the lens frame 4. The abutting portion 53 and the cylindrical inner wall 43 of the lens frame are disposed in contact with each other. That is, the liquid crystal lens 3 is positioned with respect to the lens frame 4 via the holding member 5.

  Then, in a state where the liquid crystal lens 3 and the holding member 5 are positioned in the lens frame 4, the abutting portion 53 of the holding member 5 and the cylindrical inner wall 43 of the lens frame 4 are bonded by, for example, a UV curable adhesive. Has been.

  The second optical lens 22 is fitted into the lens frame 4 from the rear in the optical axis direction, and the peripheral portion of the front surface (the liquid crystal lens 3 side) 221 of the second optical lens 22 is the liquid crystal lens 3. It is abutted against the rear surface. In this way, the second optical lens 22 is abutted against the liquid crystal lens 3 so that the distance between the rear surface of the liquid crystal lens 3 and the front surface 221 of the second optical lens 22 in the effective region is a predetermined distance. Become.

  The inner diameter of the lens frame 4 at the fixed position of the second optical lens 22 is slightly larger than the outer diameter of the second optical lens 22, and the second optical lens 22 is placed in the lens frame 4. By inserting, the second optical lens 22 is positioned in a direction perpendicular to the optical axis (center axis 42). The side surface of the second optical lens 22 is bonded to the cylindrical inner wall 43 of the lens frame 4 with, for example, a UV curable adhesive.

  Similar to the second optical lens 22, the third optical lens 23 is fitted into the lens frame 4 from the rear in the optical axis direction. Then, the third optical lens 23 is brought into contact with the peripheral portion of the front surface (the second optical lens 22 side) 231 by the peripheral portion of the rear surface 222 of the second optical lens 22, whereby the third optical lens 23. The distance in the effective area between the front surface 231 of the optical lens 23 and the rear surface 222 of the second optical lens 22 is a predetermined distance.

  Similarly to the second optical lens 22, the third optical lens 23 can be positioned in a direction perpendicular to the optical axis simply by being inserted into the lens frame 4. The side surface of the third optical lens 23 is bonded to the cylindrical inner wall 43 of the lens frame 4 by, for example, a UV curable adhesive. An adhesive other than the UV curable type may be used.

  Next, a configuration example of the liquid crystal lens 3 used in the camera lens unit of the present invention will be described. FIG. 3 is a cross-sectional view showing an example of the liquid crystal lens 3.

  As shown in FIG. 3, the liquid crystal lens 3 includes, for example, three transparent substrates 301, 302, and 303 that face each other. A transparent common electrode 304 is formed on the front side, that is, the rear surface of the transparent substrate 301 disposed on the first optical lens 21 side. A transparent pattern electrode 305 is formed on the front surface of the central transparent substrate 302, and a transparent pattern electrode 306 is formed on the rear surface of the central transparent substrate 302.

  A transparent common electrode 307 is formed on the front side of the transparent substrate 303 disposed on the rear side, that is, on the second optical lens 22 side. Between the common electrode 304 and the pattern electrode 305 and between the pattern electrode 306 and the common electrode 307, for example, homogeneously aligned liquid crystal layers 308 and 309 are sealed, respectively. That is, the liquid crystal lens 3 has a two-layer configuration including a front liquid crystal panel including the common electrode 304, the liquid crystal layer 308, and the pattern electrode 305, and a rear liquid crystal panel including the pattern electrode 306, the liquid crystal layer 309, and the common electrode 307. ing.

  Although not particularly limited, for example, the front-side liquid crystal panel and the rear-side liquid crystal panel constitute a P-wave liquid crystal lens 3a and an S-wave liquid crystal lens 3b, respectively. Thus, in order to realize a variable focus lens by performing phase modulation of light with liquid crystal, two liquid crystal lenses for P wave and S wave are required. The P-wave liquid crystal lens 3a and the S-wave liquid crystal lens 3b have the same configuration, but the alignment directions of the liquid crystal layers 308 and 309 are different by 90 °.

  This is because, when the refractive index distribution of the P-wave liquid crystal lens 3a is changed, light having a polarization plane in the same direction as the orientation direction of the P-wave liquid crystal lens 3a is affected by the change in the refractive index distribution. This is because the light having the polarization plane in the direction orthogonal to the alignment direction of the P-wave liquid crystal lens 3a is not affected by the change in the refractive index distribution. The same applies to the S-wave liquid crystal lens 3b. The P-wave liquid crystal lens 3a and the S-wave liquid crystal lens 3b are driven by a drive voltage having the same waveform. The driving voltage used here is, for example, an AC voltage that has been subjected to pulse height modulation (PHM) or pulse width modulation (PWM).

In addition, the peripheral edge of the front transparent substrate 301 and the peripheral edge of the rear transparent substrate 303 and the front and rear surfaces of the central transparent substrate 302 are sealed by seal members 310 and 311, respectively. . The thicknesses of the liquid crystal layers 308 and 309 are kept constant by the spacer members 312 and 313, respectively.
The electrode lead-out portion 32 of the pattern electrodes 305 and 306 is provided in an extension of the central transparent substrate 302, and flexible printed circuit boards (FPC) 331 and 332 are connected using an anisotropic conductive film.

  Next, configuration examples of the pattern electrodes 305 and 306 in the P-wave and S-wave liquid crystal lenses 3a and 3b will be described. FIG. 4 is a front view showing the transparent substrate 302 on which the pattern electrode 305 of the liquid crystal lens 3 is formed.

  As shown in FIG. 4, the pattern electrode 305 is not particularly limited. For example, a plurality of C-shaped ring-shaped electrodes are provided around the circumference of a plurality of concentric circles having different radii around a circular center electrode. It has an arranged pattern. An insulated space is formed between the center electrode and the innermost annular electrode and between adjacent annular electrodes. The center electrode, the innermost ring electrode, and the adjacent ring electrode are connected to each other via a ring connection part.

  The center electrode and the outermost annular electrode are connected to electrode pads 323 and 324 formed in the connection portion 32 via lead electrodes 321 and 322, respectively. In addition, the connection portion 32 is provided with an electrode pad 325 that is opposed to the pattern electrode 305 and to which a common electrode that does not appear in the drawing is connected via an extraction electrode. A common voltage is applied to the electrode pad 325.

  On the other hand, various voltages are applied to the two electrode pads 323 and 324 connected to the pattern electrode 305. Depending on the applied voltage, each of the center electrode of the pattern electrode 305 and each annular electrode is applied. The voltage values are different. That is, a voltage distribution is generated in the liquid crystal layer 308 (see FIG. 3) by the pattern electrode 305. By changing this voltage distribution, the refractive index distribution of the P-wave liquid crystal lens 3a changes, and the lens power of the P-wave liquid crystal lens 3a can be changed. The same applies to the S-wave liquid crystal lens 3b. Thereby, the liquid crystal lens 3 can be made into a convex lens state, a parallel glass state, or a concave lens state.

  Next, a configuration example for incorporating the liquid crystal lens 3 of the present invention into the lens frame 4 will be described in detail. FIG. 5 is a perspective view illustrating a configuration example of the liquid crystal lens 3 and the holding member 5.

The holding member 5 is a plastic molded body such as polycarbonate or PMMA that has a cutout portion 52 on a side corresponding to the connection portion 32 of the liquid crystal lens 3 and surrounds the liquid crystal lens 3 in a frame shape. The distance 54 between the inner walls 51 facing the liquid crystal lens 3 is slightly larger than the outer shape of the liquid crystal lens 3. A part of the frame-like outer shape has an arcuate abutting portion 53 with a radius R. The radius R of the abutting portion 53 is a through hole 45 provided in the side portion of the lens frame 4 shown in FIG.
Is inserted into the arc of the cylindrical inner wall of the lens frame 4. Here, the center of the radius R of the abutting portion 53 is set so as to coincide with the center axis 42 of the lens frame 4 at the time of installation.

  The liquid crystal lens 3 is attached to the holding member 5 by positioning so that the center of the radius R of the abutting portion 53 coincides with the optical axis of the liquid crystal lens 3. At this time, desirably, a positioning pattern 340 is formed in advance on the liquid crystal lens 3 and is adjusted and positioned using a jig so that the pattern is optically aligned with a predetermined position.

  The positioning pattern 340 is a marking that is patterned with high accuracy with respect to the optical axis of the liquid crystal lens 3 by being created in the same process as the patterning of the pattern electrodes 305 and 306 shown in FIG. Since the distance 54 of the inner wall 51 in the notch 52 provided in the holding member 5 is slightly larger than the outer diameter of the liquid crystal lens 3 in this way, the positioning pattern 340 is used for the holding member 5. Thus, the liquid crystal lens 3 can be positioned. Therefore, even if the external dimensions of the liquid crystal lens 3 processed into a rectangular shape by the scribe break method or the dicing method deviate from the design value, the liquid crystal lens 3 can be positioned at an accurate location with respect to the holding member 5.

  Then, after positioning the liquid crystal lens 3 with respect to the holding member 5 with a jig, for example, a UV adhesive is applied to the plurality of cutout portions 52 provided on the inner wall 51 facing the liquid crystal lens 3, and the liquid crystal lens 3. Is fixed to the holding member 5.

  FIG. 6 is a cross-sectional view taken along a cutting line AA in FIG. 2 and shows a state in which the holding member 5 having the liquid crystal lens 3 fixed therein is incorporated in the lens frame 4.

As shown in this figure, the holding member 5 is configured so that the arc of radius R of the abutting portion 53 abuts against the arc of the cylindrical inner wall 43 of the lens frame 4, thereby causing the holding member 5 to move in a direction perpendicular to the central axis 42 in the lens frame 4. Positioning is possible. And both are bonded by, for example, a UV curable adhesive. An adhesive other than the UV curable type may be used.
In this state, the center of the radius R of the abutting portion 53 of the holding member 5 coincides with the center axis 42 of the lens frame 4 and also coincides with the optical axis of the liquid crystal lens 3. That is, the optical axis of the liquid crystal lens 3 coincides with the central axis 42 of the lens frame 4 via the holding member 5.

  In the camera lens unit of the present invention described above, the holding member 5 with the liquid crystal lens 3 fixed at a predetermined position is brought into contact with the lens frame 4 and incorporated into the lens frame 4, so that the light of the optical lens system 2 can be obtained. The axis and the optical axis of the liquid crystal lens 3 can be matched very easily. That is, from this, the liquid crystal lens 3 has a rectangular outer shape and is manufactured by the same method as the conventional liquid crystal panel manufacturing process, and the liquid crystal lens is improved while improving cost, yield, reliability, and the like. 3 and the optical axis of another optical lens system 2 to be combined can be made to coincide with each other with high accuracy, and stable imaging characteristics can be obtained as a lens for a camera.

  Further, by bonding and integrating the liquid crystal lens 3 to the holding member 5 that is a plastic molded product, it is possible to prevent scratches and cracks that are likely to occur on the side surface of the liquid crystal lens 3 during assembly handling or the like. Further, since the adhesive is applied between the cylindrical inner wall 43 of the lens frame 4 and the holding member 5 at the time of bonding to the lens frame 4, it is applied directly to the liquid crystal lens 3 and the optical lens system 2. It is possible to prevent the lens from becoming dirty due to the protrusion of the adhesive and affecting the optical performance.

As described above, the camera lens unit according to the present invention is useful for an apparatus in which a liquid crystal lens is incorporated in a lens frame, and is particularly mounted on a camera, a digital camera, a movie camera, a camera unit of a camera-equipped mobile phone, a car, and the like. Therefore, it is suitable for the structure of a lens unit such as a camera used for a rear confirmation monitor or a camera part of an endoscope.

It is an exploded view which shows the structural example of the camera lens unit of this invention. It is sectional drawing which shows the structural example of the whole camera lens unit of this invention. It is sectional drawing which shows the structural example of the liquid crystal lens in the camera lens unit of this invention. It is a front view which shows the structural example of the pattern electrode of the liquid crystal lens in the camera lens unit of this invention. It is a perspective view which shows the structural example of the liquid crystal lens and holding member in the camera lens unit of this invention. It is sectional drawing which shows the structural example of the camera lens unit of this invention.

Explanation of symbols

2 Optical Lens System 3 Liquid Crystal Lens 4 Lens Frame 5 Holding Member 21 First Optical Lens 22 Second Optical Lens 23 Third Optical Lens 32 Electrode Extraction Portion 41 Window Portion 42 Central Axis 43 Cylindrical Inner Wall 44 Abutting Surface 45 Through Hole 51 Inner wall 52 Notch portion 53 Abutting portion 211 Front surface of the first optical lens 212 Rear surface of the first optical lens 221 Front surface of the second optical lens 222 Rear of the second optical lens Surface 231 Front surface of the third optical lens 301 Transparent substrate 302 Transparent substrate 303 Transparent substrate 304 Common electrode 305 Pattern electrode 306 Pattern electrode 307 Common electrode 308 Liquid crystal layer 309 Liquid crystal layer 310 Seal member 311 Seal member 312 Spacer member 313 Spacer member 331 FPC
332 FPC
340 Positioning pattern

Claims (3)

An optical lens system including at least one optical lens;
A variable focus liquid crystal lens having a liquid crystal layer sandwiched between two rectangular transparent substrates;
A holding member in which the liquid crystal lens is fixedly disposed;
A lens frame that interpolates the optical lens system and the holding member so that the optical axes of the optical lens and the liquid crystal lens coincide with each other, and the holding member incorporates the holding member into the lens frame. Sometimes it has an abutting part that contacts the inner wall surface of the lens frame,
The abutting portion of the holding member is brought into contact with the inner wall surface of the lens frame so that the optical axis center of the liquid crystal lens coincides with the central axis of the optical lens.
A camera lens unit characterized by that. The shape of the abutting portion and the shape of the inner wall surface of the lens frame are similar arc shapes,
The camera lens unit according to claim 1. The holding member is inserted into the lens frame from a direction orthogonal to the optical axis center of the optical lens.
The camera lens unit according to claim 1, wherein the camera lens unit is provided.

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