Method and apparatus for measuring optical characteristics of a lens unit

Abstract

The present application provides a measuring method and a measuring device capable of appropriately and accurately obtaining dynamic optical characteristics of a lens unit in lens vibration. The measuring method of the present application includes: a lens vibration step (S3, S4) in which a search mode and a drive mode are alternately repeated, the search mode is a mode in which a vibration body is vibrated by sweeping a vibration frequency within a predetermined range, thereby vibrating a predetermined lens for a predetermined duration, and the drive mode is a mode in which the vibration body is vibrated at a substantially constant frequency within a predetermined range, thereby vibrating the predetermined lens for a predetermined duration longer than the predetermined duration in the search mode; and a measuring step (S6) in which, in the lens vibration step, the optical characteristics of the lens unit are measured only when in the drive mode.

Description

Technical Field

[0001] The present invention relates to a method and apparatus for measuring the optical characteristics of a lens unit constituting an onboard camera mounted in a vehicle, such as an automobile. Background Technology

[0002] Previously, in-vehicle cameras were installed in cars to assist parking or to prevent collisions through image recognition, and their application in autonomous driving was also explored. In addition, such in-vehicle cameras and other camera modules typically include: a lens unit having a lens group consisting of multiple lenses arranged along an optical axis, a lens barrel (tube) for housing and holding the lens group, and an aperture component disposed at least at one location between the lenses in the lens group (for example, see Patent Document 1).

[0003] In addition, such lens units are sometimes installed on mounting parts such as the front grille of vehicles (cars), with the lens closest to the object protruding outwards. In such cases, foreign objects such as water droplets, mud, ice, snow, and frost can easily adhere to the surface of the lens. If these foreign objects adhere, they need to be removed to ensure a clear field of view for the lens unit.

[0004] Regarding the removal of foreign matter adhering to the surface of a lens (or lens cover), in recent years, foreign matter has also been removed by using a vibrating body to vibrate the lens (or lens cover) (ultrasonic vibration). For example, in Patent Document 2, a vibrating device for removing foreign matter such as water droplets or dust adhering to a dome-shaped cover (lens cover) is provided in a camera with a lens unit.

[0005] Specifically, such as Figure 6 As shown, such a vibration device 2 is provided on a camera body 3 with a lens 6 and a camera unit 5 containing a circuit containing an image element, and has a dome-shaped transparent cover 11, a cylindrical vibrating body 12 fixed to the cover 11, and a piezoelectric element 13 fixed to the vibrating body 12 and vibrating the cover 11 via the vibrating body 12. The vibrator 12 has: a cylindrical portion 14 having a first end 14a located on the side of the cover 11 and a second end 14b located on the opposite side of the cover 11; a cylindrical first connecting portion 15 connected to the first end 14a of the cylindrical portion 14 and formed by a cylinder with an inner diameter larger than that of the cylindrical portion 14; a first annular portion 16 located between the first connecting portion 15 and the cover 11 and having an inner diameter smaller than that of the first connecting portion 15; a second connecting portion 17 connected to the second end 14b of the cylindrical portion 14 and formed by a cylinder with an outer diameter smaller than that of the cylindrical portion 14; and a second annular portion 18 located between the second connecting portion 17 and the piezoelectric element 13 and having an outer diameter larger than that of the second connecting portion 17.

[0006] In such a vibration device 2, by driving the piezoelectric element 13 and causing the cover 11 to vibrate ultrasonically via the vibrator 12, the movement and atomization of droplets can be achieved more effectively, or foreign matter attached to the surface of the cover 11 can be removed.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2013-231993

[0010] Patent Document 2: Japanese Patent No. 6977784 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] However, the optical characteristics of the various types of lens units described above are generally measured and evaluated when the lens is fixed in a stationary state. That is, as mentioned above, even in a structure equipped with a vibration device that enables the lens to vibrate ultrasonically, the optical characteristics are still measured and evaluated in a static state where the lens is not vibrating (measuring and evaluating static optical characteristics).

[0013] However, even with a camera equipped with a vibration device that can remove foreign objects from the lens surface through ultrasonic vibration, it is still necessary to measure and evaluate the optical characteristics of the lens unit (camera) while the lens is vibrating (the necessity of measuring and evaluating dynamic optical characteristics).

[0014] Here, when measuring dynamic optical characteristics in a camera with a vibration device, obtaining appropriate and accurate measurement results becomes a significant issue. This will be explained below.

[0015] In cameras equipped with vibration devices, to effectively remove foreign objects from the lens surface, it is preferable to vibrate the vibrating body (and therefore the lens) at the natural vibration frequency of the foreign object, thereby causing the foreign object to resonate (amplify the vibration). Therefore, by alternately repeating the search mode and the drive mode, foreign objects can be effectively removed (cleaned) in a way that matches constantly changing conditions (e.g., changes in the resonant frequency due to variations in the attached foreign object or temperature). The search mode involves applying an AC output signal to a piezoelectric element (piezoelectric vibrator) to sweep the frequency within a predetermined range, and determining the natural vibration frequency of the foreign object (determining the type of foreign object) based on the measured frequency and current value. The drive mode involves continuously applying an AC output signal to the piezoelectric element, sweeping the frequency before and after the natural vibration frequency (resonant frequency) determined in the search mode, to continuously resonate (amplify the vibration) the foreign object (by continuing the vibration at the resonant frequency), thereby effectively and efficiently removing (cleaning) foreign objects from the lens surface.

[0016] However, when alternating between these two modes of ultrasonic cleaning, frequency drift will occur when the lens is vibrated to measure optical properties, or when switching modes during the measurement of optical properties, sometimes it is impossible to obtain appropriate and accurate measurement results.

[0017] The present invention was made in view of the above circumstances, and its object is to provide a method and apparatus for measuring the dynamic optical characteristics of a lens unit in lens vibration that can be appropriately and accurately obtained.

[0018] Methods for solving problems

[0019] To address the aforementioned issues, the present invention provides a measurement method for measuring the optical characteristics of a lens unit including the predetermined lens while vibrating the predetermined lens via a vibrating body, wherein the measurement method includes:

[0020] The lens vibration step alternately repeats a search mode and a drive mode. The search mode involves vibrating the vibrating body by sweeping the vibration frequency within a predetermined range, thereby causing the predetermined lens to vibrate for a predetermined duration (e.g., 0.5 seconds). The drive mode involves vibrating the vibrating body at a substantially constant frequency within the predetermined range, thereby causing the predetermined lens to vibrate for a predetermined duration (e.g., 3 seconds) longer than the predetermined duration in the search mode.

[0021] In the lens vibration step, the optical characteristics of the lens unit are measured using a predetermined measuring device only when the drive mode is in effect.

[0022] According to the structure described above, in the irregular vibration mode of a lens where two vibration modes alternately repeat, the optical characteristics of the lens unit are measured only in the drive mode where the lens is in a stable vibration operating state with a substantially constant frequency. Therefore, the dynamic optical characteristics of the lens unit during lens vibration can be obtained appropriately and accurately. Furthermore, by measuring the optical characteristics in a drive mode with a duration longer than the search mode, the time required for measuring the optical characteristics using the measuring device can be easily ensured.

[0023] In addition, such optical characteristic measurements can be performed during the pre-shipment inspection of the finished product of the lens unit or the optical device (such as a camera) containing the lens unit, or they can be performed after the lens unit is installed, that is, after the optical device such as a camera with a lens unit containing a vibrating body that vibrates the lens is placed in a predetermined installation location, when the lens vibrates (for example, in an ultrasonic vibration cleaning process in which the lens is vibrated by a vibrating body to remove foreign matter attached to the lens).

[0024] As an example, when measuring optical characteristics during the inspection of the ultrasonic vibration cleaning process, in drive mode, the vibrating body (and therefore the lens) can be vibrated at the predetermined natural vibration frequency of the foreign object. In the case of multiple foreign objects, the vibrating body (and therefore the lens) can be vibrated at several different natural vibration frequencies to obtain measurement results separately. Furthermore, in the actual ultrasonic vibration cleaning process, when measuring optical characteristics, in search mode, the vibrating body can be vibrated by sweeping the vibration frequency within a predetermined range, thereby determining the natural vibration frequency of the foreign object (determining the type of foreign object) based on the measured frequency and current value. In drive mode, the foreign object is continuously resonated (vibration is amplified) by vibrating the vibrating body at a roughly constant natural vibration frequency (resonant frequency) determined in search mode (continuing vibration at the resonant frequency).

[0025] Furthermore, in the above structure, it is preferable that the duration of the driving mode is longer than or equal to the time required for measuring the optical characteristics by the measuring instrument, and the measurement steps complete a predetermined measurement sequence of optical characteristics within a predetermined single driving mode. This facilitates significant measurements and allows for concise and efficient measurement of optical characteristics within a short time. Alternatively, in this case, the duration of the driving mode can be set based on the measurement time required by the measuring instrument.

[0026] Furthermore, in the above structure, the optical characteristics can also be measured separately and in stages within multiple driving modes during the measurement step, thereby completing a predetermined measurement sequence of the optical characteristics. Thus, the duration of the driving mode is not limited by the measurement time of the optical characteristics (and vice versa). Additionally, it avoids the limitation of the type of measuring instrument that can be used being restricted by the duration of the driving mode (and vice versa).

[0027] Furthermore, in the above structure, it is preferable that, at least in multiple driving modes involved in the measurement of optical properties, a trigger signal is output from the driving circuit that vibrates the vibrating body to the measuring device, and the measuring device measures the optical properties of the lens unit based on the trigger signal. This facilitates significant measurements and enables simple and efficient control of mode-dependent optical measurements.

[0028] Furthermore, in the above structure, the optical properties are measured using a predetermined type of measuring instrument for any predetermined measurement item, and the measured value can be obtained, for example, it can be related to MTF (Modulation Transfer Function). Additionally, as measurement items, examples include the measurement of optical properties such as focal length, field of view, image height characteristics, and peripheral light ratio, and imaging properties such as MTF and CTF. As measurement methods, examples include performing the measurement while the sample is placed in the measuring machine and measuring fixture and remains stationary during ultrasonic vibration.

[0029] In addition, the present invention also provides a measuring apparatus for performing the above-described measuring method.

[0030] Invention Effects

[0031] According to the measurement method and measuring device of the present invention, the dynamic optical characteristics of the lens unit during lens vibration can be obtained appropriately and accurately. Attached Figure Description

[0032] Figure 1 This is a schematic cross-sectional view of a camera module as an example of an optical device, which measures optical characteristics using a measuring apparatus that implements a measuring method according to an embodiment of the present invention.

[0033] Figure 2 yes Figure 1 A 3D view of the camera module.

[0034] Figure 3 This is a schematic block diagram of a measuring apparatus for implementing one embodiment of the present invention.

[0035] Figure 4 It is a timing diagram showing the frequency changes under search mode and drive mode.

[0036] Figure 5This is a flowchart illustrating an example of the steps in a measurement method according to one embodiment of the present invention.

[0037] Figure 6 It is a schematic cross-sectional view of a lens unit with an existing vibrating body. Detailed Implementation

[0038] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. These embodiments contribute to “9.1 Developing high-quality, reliable, sustainable and resilient infrastructure, including regional and transboundary infrastructure, to support economic development and enhance human well-being, with an emphasis on affordability and equitable access for all” in the United Nations Sustainable Development Goals (SDGs).

[0039] Figure 1 This is a schematic cross-sectional view of a camera module with a lens unit, which is an example of an optical device. The optical characteristics of this optical device are measured using a measuring apparatus that implements a measuring method according to one embodiment of the present invention. Figure 2 This is a 3D view of the camera module.

[0040] Furthermore, the lens unit described below is particularly a lens unit used in camera modules such as vehicle-mounted cameras, which is, for example, fixedly mounted on the outer surface of a vehicle, with wiring introduced into the vehicle to connect to a display or other device.

[0041] like Figure 1 as well as Figure 2 As shown, the camera module 300 of this embodiment includes a lens unit 20. The lens unit 20 includes a cylindrical lens barrel 22 and a square cylindrical first frame (frame) 23 in which the lens barrel 22 is disposed.

[0042] Additionally, the image side of the lens barrel 22 and the first frame 23 (in) Figure 1 The lower end (in the middle) is supported by a quadrangular cylindrical second frame 24. The length of the second frame 24 along the optical axis is shorter than that of the first frame 23, but its outer and inner diameters are longer. Furthermore, the optical axis is denoted by O, and the direction orthogonal to this optical axis O is radial.

[0043] The first frame 23 is positioned radially outward from the lens barrel 22, and the second frame 24 is positioned closer to the image side than the first frame 23. Figure 1 The lens barrel 22, the first frame 23, and the second frame 24 are configured to be coaxial. (The middle part is the lower side).

[0044] A rectangular plate-shaped inner flange 24a is formed at the upper end of the second frame 24, and a flange facing the object side is formed at the radial center of the inner flange 24a. Figure 1 A protruding convex portion 24b (the upper side) has a through hole 24c formed in the radial center of the protruding portion 24b.

[0045] Furthermore, a stepped portion 24d is formed on the upper surface of the inner flange portion 24a, and the lower end of the first frame 23 is fitted into the stepped portion 24d. Thus, the first frame 23 is positioned relative to the second frame 24 in the radial and optical axis directions.

[0046] In addition, the lens unit 20 has a plurality of lenses 31, 32, 33, 34, 35, and 36 arranged sequentially from the object side.

[0047] Lens 31 is the first lens 31 located on the side closest to the object, and the first lens 31 is disposed on the first frame 23 in such a way as to be held in the lens holding part 50 described later.

[0048] Five lenses 32, 33, 34, 35, and 36, which are positioned closer to the image side than the first lens 31, are disposed inside the lens barrel 22.

[0049] Additionally, an image-oriented side is formed at the lower end of the lens tube 22 (in Figure 1 A cylindrical protrusion 27 (located on the lower side) is inserted into and fitted into the through hole 24c provided in the second lens barrel 24. Thus, the lens barrel 22 and the second frame 24 are coaxial and aligned with the optical axis O.

[0050] In addition, the first lens 31 located on the side closest to the object is a glass lens, and lenses 32 to 36 are resin lenses, but are not limited to these (for example, lens 31 may also be a resin lens).

[0051] In addition, anti-reflective coatings, hydrophilic coatings, waterproof coatings, etc., may be provided on the surfaces of lenses 31 to 36 as needed.

[0052] Multiple lenses 31-36, fixed and supported on the first frame 23 and the lens barrel 22, are configured to align their respective optical axes and are arranged along one optical axis O, forming a lens group L for shooting.

[0053] In addition, in this embodiment, the first frame 23 is disposed on the radial outer side of the lens barrel 22.

[0054] The first frame 23 is formed of a metal such as SUS and includes: a four-cornered cylindrical frame body 23a; a rectangular plate-shaped top plate portion 23b integrally formed with the frame body 23a at its upper end; and a locking portion 23c integrally formed with the top plate portion 23b at its inner peripheral edge. That is, the top plate portion 23b of this embodiment is... Figure 6Compared to the top plate portion 105b shown, the length from the upper edge of the frame body 23a toward the inward side is shorter, and a locking portion 23c is formed on the inner peripheral edge of the top plate portion 23b.

[0055] The thickness of the top plate 23b (thickness in the optical axis direction) is thinner than the thickness of the frame body 23a (radial thickness).

[0056] The locking portion 23c includes: a generally cylindrical protrusion 23d, which is formed from the edge on the inner periphery side of the top plate portion 23b toward the object side (in... Figure 1 The upper part of the protrusion 23d protrudes outward; the pressing part 23e bends radially inward from the upper end of the protrusion 23d. An inclined surface 23f inclined relative to the optical axis O is formed on the pressing part 23e along the circumferential direction.

[0057] Furthermore, the first lens 31 is fixed by pressing the surface edge of the first lens 31 with the inclined surface 23f. That is, with the lens group L installed and held in the first frame 23 and the lens barrel 22, the first lens 31 of the lens group L located on the object side is fixed to the object side end of the first frame 23 in the optical axis direction by pressing the inclined surface 23f of the pressing part 23e.

[0058] Additionally, at the image-side end of the lens tube 22 (in Figure 1 The lower end of the lens assembly has an inner flange 26 with an opening having a diameter smaller than that of the sixth lens 36. Through the inner flange 26 and the inclined surface 23f of the pressing part 23e, the multiple lenses 31-36 constituting the lens group L are held and fixed in the optical axis direction within the first frame 23 and the lens barrel 22.

[0059] In addition, an infrared cut-off filter or other filter 99 is provided on the lower surface of the inner flange portion 26.

[0060] In addition, in this embodiment, an annular lens holding portion 50 is provided to hold the first lens 31.

[0061] The lens holding part 50 is manufactured by turning a metal such as SUS into a thin ring shape. The lens holding part 50 has a cylindrical inner circumferential surface 50a and an annular surface 50b orthogonal to the inner circumferential surface 50a on its inner circumferential side. The inner circumferential surface 50a and the annular surface 50b are formed with an L-shaped cross-section. The inner circumferential surface 50a is coaxially arranged with the optical axis O, and the annular surface 50b is orthogonal to the optical axis O.

[0062] Additionally, the lens holding portion 50 has an inner peripheral surface 50c orthogonal to the annular surface 50b and coaxially arranged with the optical axis O. This inner peripheral surface 50c is disposed on the image side closer to the inner peripheral surface 50a than the inner peripheral surface 50a. Figure 1 (The middle is the lower side), and the inner diameter is smaller than the inner circumferential surface 50a.

[0063] In addition, the inner diameter of the inner circumferential surface 50c of the annular lens holding portion 50 is larger than the outer diameter of the lens barrel 22, thereby the upper end of the lens barrel 22 is disposed inside the inner circumferential surface 50c of the lens holding portion 50.

[0064] Furthermore, the lens holding portion 50 is engaged with the first frame 23. That is, the outer peripheral surface 50d and the upper surface 50e of the lens holding portion 50 abut against the inner periphery of the pressing portion 23e of the first frame 23 with almost no gap, thereby fitting the lens holding portion 50 into the top plate portion 23b of the first frame 23. In this way, the lens holding portion 50 is engaged with the first frame 23 having the top plate portion 23b.

[0065] The lens holding part 50, which is engaged with the first frame 23, has its axis aligned with the optical axis O and is positioned in the optical axis direction.

[0066] Furthermore, the lens holding portion 50 holds the first lens 31. That is, the inner peripheral surface 50a of the lens holding portion 50 abuts against the outer peripheral surface of the first lens 31 without gap, thereby positioning the first lens 31 radially and coaxially with the optical axis O. In addition, the annular surface 50b of the lens holding portion 50 abuts against the flat bottom surface 31e of the first lens 31 facing the image side without gap, thereby positioning the first lens 31 in the optical axis direction.

[0067] In addition, the lenses 32-36, which are positioned on the image side of the first lens 31, are kept aligned with the optical axis by the lens barrel 22. The lens barrel 22 is coaxial with the second frame 24 and aligned with the optical axis O. Therefore, the first lens 31 and the lenses 32-36, which are positioned on the image side of the first lens 31, are configured to be coaxial or below a predetermined eccentricity.

[0068] In addition, this embodiment includes a vibration mechanism 60 for vibrating the first lens 31.

[0069] The vibration mechanism 60 includes an ultrasonic transducer 61 for performing ultrasonic vibration and a vibrating body 62 for transmitting the ultrasonic vibration of the transducer 61 to the first lens 31. Such a vibration mechanism 60 is positioned radially inward from the first frame 23 and radially outward from the lens barrel 22.

[0070] The oscillator 61 is formed in the shape of a circular ring plate and is disposed inside the frame body 23a of the first frame 23. The oscillator 61 is formed, for example, by a piezoelectric element.

[0071] The vibrating body 62 includes: an annular circular plate-shaped mounting portion 62a; and a main body portion 62b extending from the mounting portion 62a toward the object side (in... Figure 1The main body 62b extends from the upper side and is generally cylindrical, with its outer and inner diameters continuously varying in the axial direction (optical axis direction) to expand and contract, and has an S-shaped cross-section; and an annular joint 62c is formed at the upper end of the main body 62b. An oscillator 61 is mounted and fixed on the lower surface of the mounting portion 62a, and the upper surface of the joint 62c is bonded to the lower surface (image-side face) of the lens holding portion 50 by an adhesive.

[0072] In such a vibration mechanism 60, the oscillator 61 vibrates ultrasonically at a predetermined frequency, thereby causing the vibrator 62 to vibrate ultrasonically. When the vibrator 62 vibrates, it engages with the lens holding part 50, so the first lens 31 vibrates ultrasonically at the same frequency via the lens holding part 50, thereby removing foreign objects such as water droplets, mud, snow, and frost adhering to the lens surface 31a of the first lens 31.

[0073] The lens holding part 50 is fitted with the top plate part 23b of the first frame 23, but the thickness of the top plate part 23b is thinner than the thickness of the frame body 23a. The top plate part 23b functions as a damper, so the vibration of the lens holding part 50 is difficult to transmit to the frame body 23a. Therefore, the vibration is difficult to transmit to the second frame 24 fitted with the frame body 23a. As a result, the vibration is also difficult to transmit to the lens barrel 22 fitted with the second frame 24, and the vibration is also difficult to transmit to the lenses 32-36. This can suppress the reduction in optical performance caused by the positional displacement of the lenses 32-36 due to vibration.

[0074] In addition, in this embodiment, the lens unit 20 is composed of a first frame 23, a first lens 31 held in the first frame 23, a lens barrel 22, lenses 32-36 held in the lens barrel 22, a lens holding part 50, a vibration mechanism 60, etc.

[0075] The camera module 300 of this embodiment is composed of the lens unit 20 and the second frame 24 that fits into the first frame 23 of the lens unit 20.

[0076] The second frame 24 contains a sensor (camera element; image sensor) 304 encapsulated inside it.

[0077] The encapsulated sensor 304 is disposed inside the second housing 24 opposite to the filter 99, and is positioned to receive the image of the object formed by the lens unit 20. Furthermore, the encapsulated sensor 304 includes a CCD, CMOS, or similar sensor, and converts the light received by the lens unit 20 into an electrical signal. The converted electrical signal is then converted into analog data and digital data, which are components of the image data captured by the camera.

[0078] Furthermore, the second frame 24 contains a drive circuit board 305 inside. The drive circuit board 305 is a drive circuit 4 (see reference 4) that drives the piezoelectric element 61 of the vibration mechanism 60 by applying a voltage of a predetermined frequency. Figure 3 The drive circuit board 305 and the oscillator (piezoelectric element) 61 are formed of FPC or the like and are connected by wiring 306 passing through wiring holes 24f formed in the inner flange portion 24 of the second frame 24.

[0079] The optical characteristics of the camera module having the above structure are measured using a measuring apparatus 1 that implements a measuring method according to an embodiment of the present invention. The measuring apparatus 1 vibrates the first lens 31 via a vibrating body 62 and measures the optical characteristics of the lens unit 20 including the first lens 31, such as... Figure 3 As shown, it includes: a drive circuit 4 disposed on a drive circuit substrate 305 and vibrating a vibrator 62 (applying a voltage of a predetermined frequency to a piezoelectric element 61); a measuring device 6 for measuring the optical characteristics of the lens unit 20; and a control circuit 2 for controlling the operation of the drive circuit 4 and the measuring device 6.

[0080] In this case, the control circuit 2 controls the operation of the drive circuit 4 by alternately repeating the search mode and the drive mode, and controls the operation of the measuring device 6 so as to measure the optical characteristics of the lens unit 20 only when in the drive mode. The search mode is a mode in which the vibrating body 62 vibrates by sweeping the vibration frequency within a predetermined range, thereby causing the first lens 31 to vibrate for a predetermined duration. The drive mode is a mode in which the vibrating body 62 vibrates at a substantially constant frequency within the predetermined range, thereby causing the first lens 31 to vibrate for a predetermined duration longer than the predetermined duration in the search mode.

[0081] Specifically, as an example, during the pre-shipment inspection of camera module 300, such as... Figure 4 As shown in the time series diagram, during the search mode period (t... CYCLE During a period (e.g., a duration of 0.5 seconds), based on the control signal s2 from the control circuit, the drive circuit 4 sets the drive voltage Vdr to a predetermined voltage, which will cause the frequency f to be within f MIN ~f MAX A swept AC output signal s1 is applied to the piezoelectric element 61. Therefore, the vibrator 62 vibrates at the swept frequency, and the first lens 31 vibrates for a predetermined duration t. CYCLE It vibrates.

[0082] Furthermore, during actual ultrasonic cleaning after installation, in this search mode, a signal processing circuit (not shown) will, based on the measured resonant frequency and current value in the search mode, be within a predetermined sweep frequency range f.MIN ~f MAX The approximately constant frequency within the object is determined as the resonant frequency of the foreign object resonance. For example, if the signal processing circuit determines that the foreign object attached to the surface of the first lens 31 is water, then the resonant frequency (the natural vibration frequency of the foreign object) is f. 01 .

[0083] Then, in this search mode, the vibrator 62 is made to vibrate at a substantially constant frequency within the predetermined range (sweep range), and the first lens 31 is made to vibrate at a frequency longer than the predetermined duration (t) in the search mode. CYCLE The long predetermined duration (t) DRIVE For example, a drive mode that vibrates for 3 seconds. Specifically, as an example, drive mode A is executed, where drive circuit 4 will vibrate at the resonant frequency f. 01 The AC output signal s1, after frequency sweeping before and after, is applied to the piezoelectric element 61. More specifically, in relation to the actual ultrasonic cleaning after installation described above, in this drive mode A, the drive circuit 4 will apply a frequency ΔT to the resonant frequency f. 01 The range f before and after FS The AC output signal s1 after frequency sweep is applied to the piezoelectric element 61 (therefore, in actual ultrasonic cleaning, by continuing the resonant frequency f...). 01 The vibration prevents the temperature of the first lens 31 from rising excessively and atomizes the water (droplets) adhering to the surface of the first lens 31. Furthermore, in this example, the frequency of the AC output signal applied to the piezoelectric element 61 varies in a stepwise manner. Specifically, the frequency f of the AC output signal increases or decreases at intervals Δt. STEP Of course, frequency scanning methods are not limited to this.

[0084] Subsequently, the search pattern and drive pattern are repeated alternately, but... Figure 4 As another example of a driving mode, following driving mode A, driving mode B is also shown. In driving mode B, the driving circuit 4 is fixed at the resonant frequency f. 02 The AC output signal s1 is applied to the piezoelectric element 61 (fixed at the resonant frequency f). 02 And drive the piezoelectric element 61). Furthermore, in actual ultrasonic cleaning after installation, by alternating and repeating such a pattern, foreign matter can be effectively removed (cleaned) in a way that matches the ever-changing conditions (e.g., the resonant frequency changes due to changes in the attached foreign matter and temperature).

[0085] Furthermore, in the measuring device 1 of this embodiment, the optical characteristics of the lens unit 20 are measured only when the device is in drive mode, based on the control signal s4 sent from the control circuit 2 to the measuring device 6. In this case, the duration of the drive mode (t)DRIVE The length of the measurement unit 20 may also be greater than the time required to measure the optical characteristics of the lens unit 20 by the measuring device 6. In this case, the measuring device 6 completes a predetermined sequence of optical characteristic measurements within a predetermined single drive mode. Alternatively, the measuring device 6 may measure the optical characteristics of the lens unit 20 separately and in stages in multiple drive modes, thereby completing a predetermined sequence of optical characteristic measurements. In this case, at least in the multiple drive modes involved in measuring the optical characteristics, a trigger signal s3 may be output from the drive circuit 4 that vibrates the vibrator 62 to the measuring device 6, and the measuring device 6 measures the optical characteristics of the lens unit 20 based on the trigger signal s3.

[0086] exist Figure 5 The flowchart illustrates an example of a method for phased measurement based on trigger signal s3. As shown, in this example, firstly, lens unit 20 is initially set in measuring device 1 (step S1). Next, the measuring operator sets the measuring conditions (step S2). Then, as described above, the search mode (lens vibration step S3) and drive mode (lens vibration step S4) are alternately repeated. When trigger signal s3 is received by measuring device 6 in drive mode (if "yes" in step S5), measuring device 6 measures the optical characteristics of lens unit 20 (measurement step S6). Then, (for example, via control circuit 2) it is determined whether the measurement is complete (step S7). If the measurement is complete (if "yes" in step S7), the measurement result is output (for example, from measuring device 6) (step S8).

[0087] As explained above, according to this embodiment, in the irregular vibration mode of the first lens 31, which alternates between two vibration modes (i.e., search mode and drive mode), the optical characteristics of the lens unit 20 are measured only in the drive mode, which is the stable vibration operating state in which the first lens 31 vibrates at a substantially constant frequency. Therefore, the dynamic optical characteristics of the lens unit 20 during lens vibration can be obtained appropriately and accurately. Furthermore, by measuring the optical characteristics in the drive mode, which has a longer duration than the search mode, it is easy to ensure the time required for measuring the optical characteristics using the measuring device 6.

[0088] Furthermore, the present invention is not limited to the embodiments described above, and can be implemented in various modifications without departing from its spirit. For example, in the present invention, the shapes of the lens, frame, lens barrel, etc., are not limited to the embodiments described above. Additionally, the vibration modes of the driving mode and search mode are not limited to the embodiments described above. Furthermore, without departing from the spirit of the present invention, some or all of the embodiments described above can be combined, or a portion of an omitted structure from the embodiments described above can be used.

[0089] Explanation of reference numerals in the attached figures

[0090] 1. Measuring device

[0091] 2. Control circuit

[0092] 4. Drive circuit

[0093] 6 measuring instruments

[0094] 20 lens units

[0095] 31 First lens,

[0096] 60 vibration mechanism

[0097] 61 Piezoelectric elements

[0098] 62 Vibrating body.

Claims

1. A measurement method for measuring the optical characteristics of a lens unit including the predetermined lens while vibrating the predetermined lens via a vibrating body, characterized in that, The determination method includes: The lens vibration step alternately repeats a search mode and a drive mode. The search mode is a mode in which the vibrating body is vibrated by sweeping the vibration frequency within a predetermined range, thereby causing the predetermined lens to vibrate for a predetermined duration. The drive mode is a mode in which the vibrating body is vibrated at a substantially constant frequency within the predetermined range, thereby causing the predetermined lens to vibrate for a predetermined duration longer than the predetermined duration in the search mode. as well as In the lens vibration step, the optical characteristics of the lens unit are measured using a predetermined measuring device only when the drive mode is in effect.

2. The determination method according to claim 1, characterized in that, The duration of the driving mode is longer than the time required to measure the optical characteristics by the measuring instrument, and the measurement steps complete a predetermined measurement sequence of the optical characteristics within a predetermined single driving mode.

3. The determination method according to claim 1, characterized in that, In the measurement step, the optical properties are measured separately and in stages in multiple driving modes, thereby completing a predetermined measurement sequence of the optical properties.

4. The determination method according to claim 3, characterized in that, In at least one of the driving modes involved in the measurement of the optical properties, a trigger signal is output from the driving circuit that causes the vibrator to vibrate to the measuring device, and the measuring device measures the optical properties of the lens unit based on the trigger signal.

5. A measuring apparatus for measuring the optical characteristics of a lens unit including the predetermined lens while vibrating the predetermined lens via a vibrating body, characterized in that, The measuring device includes: A drive circuit that causes the vibrating body to vibrate; A measuring instrument for measuring the optical characteristics of the lens unit; and The control circuit controls the operation of the drive circuit and the measuring device. The control circuit controls the operation of the drive circuit to alternately repeat the search mode and the drive mode. The search mode is a mode in which the vibrating body vibrates by sweeping the vibration frequency within a predetermined range, thereby causing the predetermined lens to vibrate for a predetermined duration. The drive mode is a mode in which the vibrating body vibrates at a substantially constant frequency within the predetermined range, thereby causing the predetermined lens to vibrate for a predetermined duration longer than the predetermined duration in the search mode. The control circuit controls the operation of the measuring device so that the optical characteristics of the lens unit are measured only when the device is in the drive mode.

6. The measuring device according to claim 5, characterized in that, The duration of the driving mode is longer than the time required to measure the optical characteristics by the measuring instrument, and the measuring instrument completes a predetermined measurement sequence of the optical characteristics within a predetermined single driving mode.

7. The measuring device according to claim 5, characterized in that, The measuring device measures the optical properties separately and in stages in multiple driving modes, thereby completing a predetermined measurement sequence of the optical properties.

8. The measuring device according to claim 7, characterized in that, The driving circuit outputs a trigger signal to the measuring device in at least one of the multiple driving modes involved in the measurement of the optical properties. The measuring device measures the optical characteristics of the lens unit based on the trigger signal.

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