Method and apparatus for measuring optical characteristics of lens unit

Abstract

To provide a measurement method and a measurement apparatus capable of appropriately and accurately obtaining dynamic optical characteristics of a lens unit during lens vibration.SOLUTION: A measurement method comprises: lens vibration steps S3, S4 of alternately repeating a search mode in which a predetermined lens is vibrated for a predetermined duration by vibrating a vibrator while sweeping a vibration frequency within a predetermined range and a drive mode in which the predetermined lens is vibrated for a longer predetermined duration than the predetermined duration in the search mode by vibrating the vibrator at an approximately constant frequency within the predetermined range; and a measurement step S6 of measuring optical characteristics of the lens unit only during the drive mode in the lens vibration steps.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a measurement method and a measurement device for measuring the optical characteristics of a lens unit that constitutes an on-board camera mounted on a vehicle such as an automobile. [Background technology]

[0002] Conventionally, automobiles have been equipped with on-board cameras to support parking and prevent collisions through image recognition, and attempts have also been made to apply them to autonomous driving. In addition, camera modules such as such on-board cameras generally include a lens unit having a lens group consisting of multiple lenses arranged along an optical axis, a lens barrel that houses and holds this lens group, and an aperture member arranged between at least one of the lenses in the lens group (see, for example, Patent Document 1).

[0003] In addition, such lens units may be attached to a mounting portion such as the front grille of a vehicle (automobile), with the lens closest to the object exposed to the outside. In such cases, foreign matter such as water droplets, muddy water, ice, snow, and frost easily adheres to the surface of the lens. If this happens, it is necessary to remove the foreign matter to ensure a clear field of view for observation using the lens unit.

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

[0005] Specifically, as shown in Figure 6, such a vibration device 2 is provided in a camera that has an imaging unit 5 with a lens 6 and a circuit including an imaging element built in at the top of the camera body 3, and is equipped with a dome-shaped transparent cover 11, a cylindrical vibrating body 12 to which the cover 11 is fixed, and a piezoelectric element 13 that is fixed to the vibrating body 12 and vibrates the cover 11 via the vibrating body 12. The vibrating body 12 has a cylindrical portion 14 having a first end 14a located on the cover 11 side and a second end 14b located on the opposite side from the cover 11, a cylindrical first connecting portion 15 connected to the first end 14a of the cylindrical portion 14 and consisting of a cylinder with an inner diameter larger than that of the cylindrical portion 14, a first ring-shaped portion 16 interposed 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 consisting of a cylinder with an outer diameter smaller than that of the cylindrical portion 14, and a second ring-shaped portion 18 interposed 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 ultrasonically vibrating the cover 11 via the vibrating body 12, the movement and atomization of droplets can be more effectively achieved, or foreign matter adhering to the surface of the cover 11 can be removed. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-231993 [Patent Document 2] Patent No. 6977784 Summary of the Invention [Problem to be solved by the invention]

[0008] Incidentally, the optical characteristics of the various types of lens units described above are generally measured and evaluated while the lens is fixed and immobile. That is, even in the configuration including the vibration device capable of ultrasonically vibrating the lens as described above, the optical characteristics are measured and evaluated while the lens is in a static state without being vibrated (static optical characteristics are measured and evaluated).

[0009] However, in the presence of a camera equipped with the aforementioned vibration device that can remove foreign matter from the lens surface using ultrasonic vibration, there is also a need to measure and evaluate the optical characteristics of the lens unit (camera) while the lens is vibrating (the need to measure and evaluate dynamic optical characteristics).

[0010] When measuring dynamic optical characteristics in a camera equipped with a vibration device, a major issue is whether appropriate and accurate measurement results can be obtained. This will be explained below.

[0011] In order to effectively remove foreign matter from the lens surface in a camera equipped with a vibration device, it is desirable to vibrate the vibrating body (and therefore the lens) at the natural frequency of the foreign matter to resonate (amplify vibration) the foreign matter. For this reason, a search mode is used in which an AC output signal whose frequency is swept over a predetermined range is applied to a piezoelectric element (piezoelectric vibrator) to identify the natural frequency of the foreign matter (identify the type of foreign matter) from the measurement results of the frequency and current value at that time, and a drive mode is used in which an AC output signal whose frequency is swept around the natural frequency (resonance frequency) identified in the search mode is continuously applied to the piezoelectric element to continuously resonate (amplify vibration) the foreign matter (by continuing to vibrate at the resonant frequency) to effectively and efficiently remove the foreign matter from the lens surface (clean the foreign matter) by alternately repeating these modes, thereby enabling constant and effective removal (cleaning) of foreign matter in accordance with ever-changing conditions (for example, conditions in which the resonant frequency fluctuates due to changes in the foreign matter attached or temperature changes).

[0012] However, in ultrasonic cleaning methods that alternate between these two modes, frequency drift may occur when vibrating the lens to measure its optical properties, or the mode may switch during the measurement of the optical properties, making it difficult to obtain appropriate and accurate measurement results.

[0013] The present invention has been made in view of the above circumstances, and has as its object to provide a measurement method and a measurement device that can appropriately and accurately obtain the dynamic optical characteristics of a lens unit during lens vibration. [Means for solving the problem]

[0014] In order to solve the above problem, the present invention provides a measurement method for measuring optical characteristics of a lens unit including a predetermined lens while vibrating the predetermined lens via a vibrating body, the method comprising: a lens vibration step that alternately repeats a search mode in which the vibration frequency is swept within a predetermined range to vibrate the vibrating body, thereby vibrating the predetermined lens for a predetermined duration (e.g., 0.5 seconds), and a drive mode in which the vibration body is vibrated at a substantially constant frequency within the predetermined range, thereby vibrating the predetermined lens for a predetermined duration (e.g., 3 seconds) longer than the predetermined duration in the search mode; a measuring step of measuring optical characteristics of the lens unit using a predetermined measuring device only when the lens unit is in the drive mode during the lens vibration step; The present invention is characterized by comprising:

[0015] According to the above-described configuration of the present invention, even in an irregular vibration form of the lens in which two vibration modes are alternately repeated, the optical characteristics of the lens unit are measured only in the drive mode in which the lens is in a stable vibration operating state in which the lens vibrates at a substantially constant frequency, making it possible to appropriately and accurately obtain the dynamic optical characteristics of the lens unit during lens vibration. Furthermore, because the optical characteristics are measured in the drive mode, which has a longer duration than the search mode, it is easy to ensure the time required to measure the optical characteristics using a measuring device.

[0016] Furthermore, such measurement of optical properties may be performed during an inspection process before shipment of the lens unit or a finished optical device (such as a camera) that includes the lens unit, or may be performed after the lens unit has been mounted, i.e., after an optical device such as a camera equipped with a lens unit that includes a vibrating body that vibrates the lens has been installed in a predetermined installation location, while the lens is vibrating (for example, during an ultrasonic vibration cleaning process in which the lens is vibrated by a vibrating body to remove foreign matter adhering to the lens).

[0017] For example, when measuring optical characteristics during an inspection simulating the ultrasonic vibration cleaning process, the vibrating body (and therefore the lens) may be vibrated at the natural frequency of a specific contaminant in drive mode. If multiple types of contaminants are anticipated, the vibrating body (and therefore the lens) may be vibrated at multiple different natural frequencies corresponding to the contaminants to obtain individual measurement results. Furthermore, when measuring optical characteristics during an actual ultrasonic vibration cleaning process, the vibrating body may be vibrated by sweeping the vibration frequency within a predetermined range in search mode, and the natural frequency of the contaminant (the type of contaminant) may be identified from the measurement results of the frequency and current value at that time. Then, in drive mode, the vibrating body may be vibrated at a substantially constant natural frequency (resonance frequency) identified in search mode, causing the contaminant to continuously resonate (amplify vibration) (continue to vibrate at the resonant frequency).

[0018] In the above configuration, it is preferable that the duration of the drive mode is equal to or longer than the time required to measure the optical characteristics using a measuring device, and that the measurement step completes a predetermined measurement sequence of the optical characteristics within a single drive mode. This facilitates meaningful measurements and enables the optical characteristics to be measured simply, efficiently, and in a short time. In this case, the duration of the drive mode may be set based on the time required for measurement using the measuring device.

[0019] In the above configuration, the measurement step may be divided into a plurality of drive modes and measure the optical characteristics stepwise to complete the predetermined measurement sequence of the optical characteristics. This avoids the duration of the drive modes being constrained by the measurement time of the optical characteristics (and vice versa). It also avoids the type of measurement device that can be used being limited by the duration of the drive modes (and vice versa).

[0020] In the above configuration, it is also preferable that, in at least a plurality of drive modes involved in the measurement of optical characteristics, a trigger signal be output from the drive circuit that vibrates the vibrating body to the measuring instrument, and the measuring instrument measure the optical characteristics of the lens unit based on this trigger signal. This facilitates meaningful measurements and enables simple and efficient control of mode-dependent optical measurements.

[0021] In the above configuration, the measurement of optical characteristics is performed by obtaining a measurement value for any predetermined measurement item using a predetermined type of measuring device, which may be related to MTF (Modulation Transfer Function), for example. Examples of measurement items include optical performance such as focal length, angle of view, image height characteristics, and peripheral illumination ratio, and imaging performance such as MTF and CTF. Examples of measurement methods include placing a test sample on a measuring device or measuring jig and performing measurement while the sample remains motionless during ultrasonic vibration.

[0022] The present invention also provides a measuring device for carrying out the measuring method. [Effects of the Invention]

[0023] According to the measuring method and measuring device of the present invention, the dynamic optical characteristics of a lens unit during lens vibration can be obtained appropriately and accurately. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a schematic cross-sectional view of a camera module as an example of an optical device whose optical characteristics are measured by a measurement device that performs a measurement method according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of the camera module of FIG. 1. [Figure 3] 1 is a schematic block diagram of a measurement device that performs a measurement method according to an embodiment of the present invention. [Figure 4] 10 is a timing chart showing frequency changes in a search mode and a drive mode. [Figure 5] 1 is a flowchart of an example of steps of a measurement method according to an embodiment of the present invention. [Figure 6] FIG. 10 is a schematic cross-sectional view of a lens unit including a conventional vibrating body. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. This embodiment contributes to the achievement of "9. Industry, innovation and infrastructure" of the Sustainable Development Goals (SDGs) advocated by the United Nations, which states, "9.1 Develop quality, reliable, sustainable and resilient infrastructure, including regional and transborder infrastructure, to support economic development and human well-being, with a focus on affordable and equitable access for all."

[0026] FIG. 1 is a schematic cross-sectional view of a camera module equipped with a lens unit as an example of an optical device whose optical characteristics are measured by a measurement device that performs a measurement method according to one embodiment of the present invention, and FIG. 2 is a perspective view of this camera module. The lens unit described below is particularly intended for use in a camera module such as an in-vehicle camera, and is, for example, fixedly installed on the exterior surface of the vehicle, with wiring leading into the vehicle and connected to a display or other device.

[0027] 1 and 2, 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 housing (housing) 23 in which the lens barrel 22 is provided.

[0028] The image-side (lower side in FIG. 1) ends of lens barrel 22 and first housing 23 are supported by square cylindrical second housing 24. The length of second housing 24 in the optical axis direction is shorter than that of first housing 23, but the outer diameter and inner diameter are longer than those of first housing 23. The optical axis is indicated by O, and the direction perpendicular to this optical axis O is the radial direction.

[0029] First housing 23 is disposed radially outward from lens barrel 22, and second housing 24 is disposed closer to the image side (lower side in FIG. 1) than first housing 23. Lens barrel 22, first housing 23, and second housing 24 are disposed coaxially. A rectangular plate-shaped inner flange portion 24a is formed at the upper end of the second housing 24, and a convex portion 24b that protrudes toward the object side (upward in Figure 1) is formed at the radial center of this inner flange portion 24a, and a through hole 24c is formed at the radial center of this convex portion 24b.

[0030] Furthermore, a step portion 24d is formed on the upper surface of the inner flange portion 24a, and the lower end portion of the first housing 23 is fitted into this step portion 24d, thereby positioning the first housing 23 relative to the second housing 24 in the radial direction and the optical axis direction.

[0031] The lens unit 20 also includes a plurality of (for example, six) lenses 31, 32, 33, 34, 35, and 36 arranged in order from the object side. The lens 31 is a first lens 31 located closest to the object side, and this first lens 31 is provided in the first housing 23 and held by a lens holding portion 50, which will be described later. Five lenses 32 , 33 , 34 , 35 , and 36 arranged closer to the image side than the first lens 31 are provided inside the lens barrel 22 .

[0032] Furthermore, a cylindrical protrusion 27 that protrudes toward the image side (downward in FIG. 1) is formed at the lower end of lens barrel 22, and this protrusion 27 is inserted into and fitted into the through-hole 24c provided in second lens barrel 24. As a result, lens barrel 22 and second housing 24 are provided coaxially and coincident with optical axis O.

[0033] Furthermore, the first lens 31 located closest to the object side is a glass lens, and the lenses 32 to 36 are resin lenses, but this is not limiting (for example, the lens 31 may be a resin lens). Furthermore, the surfaces of the lenses 31 to 36 may be provided with an anti-reflection film, a hydrophilic film, a water-repellent film, or the like, as required.

[0034] The multiple lenses 31 to 36 fixed to and supported by the first housing 23 and the lens barrel 22 are arranged with their optical axes aligned, and the lenses 31 to 36 are lined up along a single optical axis O to form a single lens group L used for imaging.

[0035] In this embodiment, the first housing 23 is disposed radially outward from the lens barrel 22. The first housing 23 is made of metal such as SUS, and includes a rectangular cylindrical housing main body 23a, a rectangular plate-shaped top plate portion 23b formed integrally with the housing main body 23a at the upper end of the housing main body 23a, and a locking portion 23c formed integrally with the top plate portion 23b on the inner peripheral edge of the top plate portion 23b. That is, the length of the top plate portion 23b in this embodiment extending from the upper edge of the housing main body 23a toward the inside is shorter than that of the top plate portion 105b shown in FIG. 6, and the locking portion 23c is formed on the inner peripheral edge of the top plate portion 23b. The thickness of the top plate portion 23b (thickness in the optical axis direction) is thinner than the thickness of the housing body 23a (thickness in the radial direction).

[0036] The locking portion 23c includes a generally cylindrical protruding portion 23d formed to protrude from the inner peripheral edge of the top plate portion 23b toward the object side (upper side in FIG. 1), and a pressing portion 23e bent radially inward from the upper end of the protruding portion 23d. An inclined surface 23f inclined with respect to the optical axis O is formed along the circumferential direction on the pressing portion 23e. Then, inclined surface 23f presses the surface edge of first lens 31, thereby fixing first lens 31. In other words, in a state in which lens group L is incorporated, housed, and held within first housing 23 and lens barrel 22, inclined surface 23f of pressing portion 23e presses first lens 31, which is positioned closest to the object side of lens group L, and fixes it to the object-side end of first housing 23 in the optical axis direction.

[0037] Furthermore, an inner flange portion 26 having an opening with a diameter smaller than that of sixth lens 36 is provided at the image side end (the lower end in FIG. 1) of lens barrel 22. A plurality of lenses 31-36 constituting lens group L within first housing 23 and lens barrel 22 are held and fixed in the optical axis direction by this inner flange portion 26 and inclined surface 23f of pressing portion 23e. Further, a filter 99 such as an infrared cut filter is provided on the lower surface of the inner flange portion 26 .

[0038] In this embodiment, a ring-shaped lens holding portion 50 that holds the first lens 31 is provided. The lens holder 50 is manufactured by turning a metal such as stainless steel into a thin ring shape. The lens holder 50 has an inner peripheral surface 50a that is cylindrical and an annular surface 50b that is perpendicular to the inner peripheral surface 50a, with the inner peripheral surface 50a and the annular surface 50b being formed with an L-shaped cross section. The inner peripheral surface 50a is arranged coaxially with the optical axis O, and the annular surface 50b is arranged perpendicular to the optical axis O. In addition, the lens holding portion 50 has an inner surface 50c that is perpendicular to the annular surface 50b and is arranged coaxially with the optical axis O, and this inner surface 50c is arranged closer to the image side (lower side in Figure 1) than the inner surface 50a, and has a smaller inner diameter dimension than the inner surface 50a.

[0039] In addition, the inner diameter dimension of the inner surface 50c of the ring-shaped lens holding portion 50 is larger than the outer diameter dimension of the lens barrel 22, so that the upper end of the lens barrel 22 is positioned inside the inner surface 50c of the lens holding portion 50. The lens holding part 50 is also joined to the first housing 23. That is, the outer peripheral surface 50d and the top surface 50e of the lens holding part 50 each abut against the inner periphery of the pressing part 23e of the first housing 23 with almost no gap, whereby the lens holding part 50 is fitted into the top plate part 23b of the first housing 23. In this way, the lens holding part 50 is joined to the first housing 23 having the top plate part 23b. The lens holder 50 joined to the first housing 23 has an axis that coincides with the optical axis O, and is positioned in the optical axis direction.

[0040] The lens holder 50 holds the first lens 31. That is, the inner peripheral surface 50a of the lens holder 50 abuts tightly against the outer peripheral surface of the first lens 31, thereby positioning the first lens 31 in the radial direction and disposing it coaxially with the optical axis O. The annular surface 50b of the lens holder 50 abuts tightly against the flat bottom surface 31e of the first lens 31 facing the image side, thereby positioning the first lens 31 in the optical axis direction. Furthermore, lenses 32 to 36, which are arranged closer to the image side than first lens 31, are held by lens barrel 22 so that their optical axes are aligned, and lens barrel 22 is arranged coaxially with second housing 24 and aligned with optical axis O, so that first lens 31 and lenses 32 to 36, which are arranged closer to the image side than first lens 31, are arranged coaxially or with an eccentricity of less than a predetermined amount.

[0041] In this embodiment, a vibration mechanism 60 that vibrates the first lens 31 is provided. The vibration mechanism 60 includes a vibrator 61 that generates ultrasonic vibrations, and a vibrating body 62 that transmits the ultrasonic vibrations of the vibrator 61 to the first lens 31. The vibration mechanism 60 is disposed radially inward from the first housing 23 and radially outward from the lens barrel 22. The vibrator 61 is formed in the shape of an annular plate, and is provided inside the housing main body 23a of the first housing 23. The vibrator 61 is formed of, for example, a piezoelectric element.

[0042] The vibrating body 62 includes a donut-shaped disk-shaped mounting portion 62a, a main body 62b that extends from the mounting portion 62a toward the object side (upward in FIG. 1) and has a generally cylindrical shape with bulges and constrictions with an S-shaped cross section, with the outer and inner diameters varying continuously in the axial direction (optical axis direction), and a ring-shaped joint portion 62c formed at the upper end of the main body 62b. The vibrator 61 is fixed to the lower surface of the mounting portion 62a, and the upper surface of the joint portion 62c is bonded to the lower surface (surface facing the image side) of the lens holding portion 50 with an adhesive.

[0043] In such vibration mechanism 60, vibrator 61 ultrasonically vibrates at a predetermined frequency, causing vibrating body 62 to ultrasonically vibrate. When vibrating body 62 vibrates, first lens 31 ultrasonically vibrates at the same frequency via lens holding part 50, since vibrating body 62 is joined to lens holding part 50, thereby removing foreign matter such as water droplets, muddy water, ice, snow, and frost from lens surface 31 a of first lens 31.

[0044] The lens holder 50 is fitted to the top panel 23b of the first housing 23, but the thickness of the top panel 23b is thinner than the thickness of the housing main body 23a, and the top panel 23b functions as a damper, so that vibrations of the lens holder 50 are less likely to be transmitted to the housing main body 23a. This makes it less likely that vibrations will be transmitted to the second housing 24 fitted to the housing main body 23a, and as a result, vibrations are less likely to be transmitted to the lens barrel 22 fitted to the second housing 24, and therefore to the lenses 32-36, thereby preventing a deterioration in optical performance caused by displacement of the lenses 32-36 due to vibrations.

[0045] In addition, in this embodiment, the lens unit 20 is composed of the first housing 23, the first lens 31 held in the first housing 23, the lens barrel 22, the lenses 32 to 36 held in the lens barrel 22, the lens holding portion 50, the vibration mechanism 60, etc. The lens unit 20 and the second housing 24 fitted into the first housing 23 of the lens unit 20 constitute the camera module 300 of this embodiment. The second housing 24 includes a package sensor (image sensor) 304 therein.

[0046] Package sensor 304 is disposed inside second housing 24 facing filter 99, and is positioned to receive the image of an object formed by lens unit 20. Package sensor 304 also includes a CCD, CMOS, or the like, and converts light that is collected through lens unit 20 and reaches it into an electrical signal. The converted electrical signal is then converted into analog data or digital data, which are components of image data captured by the camera.

[0047] The second housing 24 also includes a drive circuit board 305 therein. The drive circuit board 305 is a board having a drive circuit 4 (see FIG. 3) that applies a voltage of a predetermined frequency to the piezoelectric element 61 of the vibration mechanism 60 to drive it. The drive circuit board 305 and the vibrator (piezoelectric element) 61 are formed of an FPC or the like, and are connected by a wire 306 that passes through a wiring hole 24f formed in the inner flange portion 24 of the second housing 24.

[0048] The optical characteristics of a camera module configured as described above are measured by a measuring device 1 that performs a measurement method according to one embodiment of the present invention. The measuring device 1 measures the optical characteristics of the lens unit 20 that includes the first lens 31 while vibrating the first lens 31 via a vibrating body 62, and as shown in Fig. 3, the measuring device 1 includes a driving circuit 4 that is provided on a driving circuit board 305 and vibrates the vibrating body 62 (applying a voltage of a predetermined frequency to the piezoelectric element 61), a measuring device 6 that measures the optical characteristics of the lens unit 20, and a control circuit 2 that controls the operation of the driving circuit 4 and the measuring device 6.

[0049] In this case, the control circuit 2 controls the operation of the drive circuit 4 to alternate between a search mode in which the vibration frequency is swept within a predetermined range to vibrate the vibrating body 62, thereby vibrating the first lens 31 for a predetermined duration, and a drive mode in which the vibrating body 62 is vibrated at an approximately constant frequency within the predetermined range, thereby vibrating the first lens 31 for a predetermined duration longer than the predetermined duration in the search mode, and also controls the operation of the measuring instrument 6 to measure the optical characteristics of the lens unit 20 only when in the drive mode.

[0050] Specifically, as an example, during inspection before shipping of the camera module 300, as shown in the timing chart of FIG. 4, the period of the search mode (t CYCLE In this period (for example, a duration of 0.5 seconds), the drive circuit 4 sets the drive voltage Vdr to a predetermined voltage and the frequency f to f MIN ~f MAX The AC output signal s1 swept to a frequency of 100 kHz is applied to the piezoelectric element 61. Therefore, the vibrating body 62 vibrates at the swept frequency, and the first lens 31 vibrates for a predetermined duration t CYCLE The vibration is vibrated over a range of .

[0051] During ultrasonic cleaning after actual mounting, in this search mode, a signal processing circuit (not shown) for example, performs a predetermined sweep range f based on the measurement results of the resonance frequency and current value in the search mode. MIN ~f MAX For example, the signal processing circuit determines that the foreign matter adhering to the surface of the first lens 31 is water, that is, the resonant frequency (the natural frequency of the foreign matter) is f 01 It is determined that this is the case.

[0052] Following this search mode, the first lens 31 is vibrated for a predetermined duration (t CYCLE ) for a given duration (t DRIVE For example, a drive mode is performed in which the drive circuit 4 vibrates for a period of time (for example, 3 seconds). Specifically, as an example, the drive circuit 4 vibrates at a resonance frequency f 01 In drive mode A, the AC output signal s1 swept between the resonant frequency f and the resonant frequency f is applied to the piezoelectric element 61. More specifically, in relation to the above-mentioned actual ultrasonic cleaning after mounting, in drive mode A, the drive circuit 4 sweeps the AC output signal s1 between the resonant frequency f and the resonant frequency f for a period ΔT. 01 Range around f FS The AC output signal s1 swept over the resonant frequency f is applied to the piezoelectric element 61 (in actual ultrasonic cleaning, 01 By continuing the vibration at this frequency, it is possible to prevent the temperature of the first lens 31 from rising excessively, and to atomize the water (droplets) adhering to the surface of the first lens 31. In this example, the frequency of the AC output signal applied to the piezoelectric element 61 changes in a stepwise manner. Specifically, the AC output signal changes at a frequency f every period Δt. STEP Of course, the sweep form is not limited to this.

[0053] Thereafter, the search mode and the drive mode are alternately repeated. FIG. 4 also shows a drive mode B following the search mode after the drive mode A as another example of the drive mode. In this drive mode B, the drive circuit 4 operates at a resonant frequency f 02 and apply an AC output signal s1 to the piezoelectric element 61 (resonance frequency f 02 (The piezoelectric element 61 is driven by fixing the piezoelectric element 61 in place.) In actual ultrasonic cleaning after mounting, these modes are alternately repeated to ensure that foreign matter is always effectively removed (cleaned) in accordance with the ever-changing conditions (for example, changes in the type of foreign matter adhering or changes in the temperature causing the resonance frequency to fluctuate).

[0054] In the measurement device 1 according to this embodiment, the optical characteristics of the lens unit 20 are measured only when the device is in the drive mode, based on the control signal s4 sent from the control circuit 2 to the measurement device 6. In this case, the duration of the drive mode (t DRIVE The length of the period s3 may be equal to or longer than the time required for the measuring instrument 6 to measure the optical characteristics of the lens unit 20, in which case the measuring instrument 6 completes a predetermined measurement sequence of the optical characteristics within a single predetermined drive mode. Alternatively, the measuring instrument 6 may complete the predetermined measurement sequence of the optical characteristics by dividing the measurement sequence across a plurality of drive modes and measuring the optical characteristics of the lens unit 20 in stages. In this case, a trigger signal s3 may be output to the measuring instrument 6 from the driving circuit 4 that vibrates the vibrating body 62, at least in a plurality of drive modes involved in the measurement of the optical characteristics, and the measuring instrument 6 may measure the optical characteristics of the lens unit 20 based on this trigger signal s3.

[0055] An example of the method steps for stepwise measurement based on trigger signal s3 is shown in a flowchart in FIG. 5. As shown in the figure, in this example, first, lens unit 20 is placed in measurement device 1 (step S1). Next, measurement conditions are set by a person performing the measurement (step S2). Thereafter, as described above, search mode (lens vibration step S3) and drive mode (lens vibration step S4) are alternately repeated. When trigger signal s3 is received by measurement device 6 in drive mode (YES in step S5), optical characteristics of lens unit 20 are measured by measurement device 6 (measurement step S6). Then, it is determined (e.g., by control circuit 2) whether measurement is complete (step S7). If measurement is complete (YES in step S7), the measurement results are output (e.g., from measurement device 6) (step S8).

[0056] As described above, according to this embodiment, in an irregular vibration form of the first lens 31 in which two vibration modes (i.e., search mode and drive mode) are alternately repeated, the optical characteristics of the lens unit 20 are measured only in drive mode, which is a stable vibration operating state in which the first lens 31 vibrates at a substantially constant frequency, making it possible to appropriately and accurately obtain the dynamic optical characteristics of the lens unit 20 during lens vibration. Also, because the optical characteristics are measured in drive mode, which has a longer duration than search mode, it is easy to ensure the time required to measure the optical characteristics by the measuring device 6.

[0057] The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the present invention, the shapes of the lens, housing, lens barrel, etc. are not limited to the above-described embodiments. Furthermore, the vibration patterns in the drive mode and search mode are not limited to the above-described embodiments. Furthermore, without departing from the spirit of the present invention, some or all of the above-described embodiments may be combined, or part of the configuration of one of the above-described embodiments may be omitted. [Explanation of symbols]

[0058] 1. Measuring equipment 2. Control circuit 4. Drive circuit 6 Measuring instruments 20 Lens unit 31 First lens 60 Vibration mechanism 61 Piezoelectric element 62 Vibration body

Claims

1. A measurement method for measuring optical characteristics of a lens unit including a predetermined lens while vibrating the predetermined lens via a vibrating body, comprising: a lens vibration step that alternately repeats a search mode in which the vibration frequency is swept within a predetermined range to vibrate the vibrating body, thereby vibrating the predetermined lens for a predetermined duration, and a drive mode in which the vibration body is vibrated at a substantially constant frequency within the predetermined range, thereby vibrating the predetermined lens for a predetermined duration that is longer than the predetermined duration in the search mode; a measuring step of measuring optical characteristics of the lens unit using a predetermined measuring device only when the lens unit is in the drive mode during the lens vibration step; A measuring method comprising:

2. 2. The measurement method according to claim 1, wherein the duration of the drive mode is equal to or longer than the time required to measure the optical characteristics by the measuring device, and the measuring step completes a predetermined measurement sequence of the optical characteristics within a predetermined one run of the drive mode.

3. 2. The measurement method according to claim 1, wherein the measuring step completes a predetermined measurement sequence of the optical characteristics by measuring the optical characteristics stepwise over a plurality of the drive modes.

4. 4. The measurement method according to claim 3, wherein, in at least the plurality of drive modes involved in the measurement of the optical characteristics, a trigger signal is output from a drive circuit that vibrates the vibrating body to the measuring instrument, and the measuring instrument measures the optical characteristics of the lens unit based on this trigger signal.

5. 1. A measuring device for measuring optical characteristics of a lens unit including a predetermined lens while vibrating the predetermined lens via a vibrating body, comprising: a drive circuit for vibrating the vibrating body; a measuring instrument for measuring optical characteristics of the lens unit; a control circuit for controlling the operation of the drive circuit and the measuring device; Equipped with The control circuit controlling the operation of the drive circuit to alternately repeat a search mode in which the vibration frequency is swept within a predetermined range to vibrate the vibrating body, thereby vibrating the predetermined lens for a predetermined duration, and a drive mode in which the vibration frequency is swept within a predetermined range to vibrate the vibrating body for a predetermined duration that is longer than the predetermined duration in the search mode; controlling the operation of the measuring instrument to measure the optical characteristics of the lens unit only when the lens unit is in the drive mode; A measuring device characterized by:

6. 6. The measurement device of claim 5, wherein the duration of the drive mode is equal to or greater than the time required for the measurement device to measure the optical characteristics, and the measurement device completes a predetermined measurement sequence of the optical characteristics within a given run of the drive mode.

7. 6. The measurement apparatus according to claim 5, wherein the measurement device completes a predetermined measurement sequence of the optical characteristics by measuring the optical characteristics stepwise in a divided manner across a plurality of the drive modes.

8. the drive circuit outputs a trigger signal to the measurement device in at least the plurality of drive modes related to the measurement of the optical characteristic; the measuring instrument measures the optical characteristics of the lens unit based on the trigger signal.

8. The measuring device according to claim 7.

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