JP2002267960A - Method and device for vibration analysis of optical equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration analyzing method of optical equipment by which the influence of vibration in the actual operation of an optical equipment given to the performance of the optical equipment can accurately be known. SOLUTION: The vibration analyzing method of optical equipment for analyzing the influence of the vibration of an optical component constituting the optical equipment given to the performance of the optical equipment, includes a vibration measuring process (S1) of actually measuring the vibration frequency and amplitude of the optical component, a numerical model generating process (S2) of generating a simulation model of a finite element method according to information on the measured vibration frequency and amplitude of the optical component, a vibration computing process (S3) of computing the vibration by using the simulation model generated by the numerical model generating process, a curved surface fitting process of approximating the deformation state due to the vibration of the optical component computed by the vibration computing process with a shape function capable of unique shape representation in a three-dimensional space, and an optical computing process (S4) of computing characteristics related to the performance of the optical equipment according to the shape function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for designing an optical device mounted on an electrophotographic image forming apparatus such as a copying machine or a laser beam printer, or an optical device for controlling an autofocus function of a camera. The present invention relates to a method and an apparatus for analyzing vibration of an optical device, in which the influence of the deformation of an optical component that may occur under the actual use condition of the device on the performance degradation of the device is analyzed in detail, so that the direction of the design improvement is clearly found. Things.

[0002]

2. Description of the Related Art The design of an optical unit to be mounted on a copying machine, an LBP (laser beam printer), or the like is such that each unit is kept stationary and the arrangement in a three-dimensional space is determined by calculating an optical path. The calculation of the optical path has been performed by expressing the shapes of the light transmitting portion and the reflecting portion of each unit as a function by a spatial variable and using various principles such as straight traveling, reflection, and refraction of light.

[0003] During the actual operation of products such as copiers and LBP,
Each optical unit vibrates, and an optical path designed on the assumption that the optical unit is stationary changes. The change of the optical path due to the vibration of the optical unit is described in JP-A-11-11913.
Japanese Patent Laid-Open No. 6-2006 proposes a method of expressing an optical unit by a finite element model and calculating a change amount by simulation of a vibration state.

[0004] Techniques for actually measuring the vibration behavior of an optical component using a piezoelectric acceleration sensor and an FFT analyzer have also become widespread.

[0005]

In recent years, with the increase in speed and image quality of printers, deformation of optical units, such as vibration of optical units during actual operation and thermal distortion of optical units caused by temperature rise inside the machine, has been increasing. The effect on the image is no longer negligible.

In order to provide a printer with higher image quality, in addition to calculating the optical path in an ideal situation where each optical unit is stationary, the influence of the deformation generated in the optical unit on the optical path must be accurately considered. Therefore, it is necessary to determine the arrangement of each optical unit.

However, the above conventional example (Japanese Patent Laid-Open No. 11-1)
19136) has a drawback that the amplitude value of each optical unit determined by the damping effect cannot be easily predicted only by the vibration simulation by the finite element method, and the range of the system in which the optical path can be calculated accurately is limited. there were.

On the other hand, it is possible to measure the vibration state of a device by using a piezoelectric acceleration sensor and an FFT analyzer. However, when obtaining an optical path during vibration, the number of measurement points is limited by the wiring of the sensor inside the device. Physical problems were inadequate. In addition, to measure an optical path due to rotation fluctuation of the optical unit, two rotation points of the piezoelectric acceleration sensor which can measure only the amplitude in the translation direction are used, and the rotation angle is measured from the response at the two points and the distance between the two points. be able to. However, as the size of the optical component to be measured becomes smaller relative to the size of the sensor, it becomes more difficult to accurately measure the rotation angle, and there is a disadvantage that a minute rotation fluctuation of the optical unit cannot be measured.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an optical device capable of accurately knowing the influence of the vibration during the actual operation of the optical device on the performance of the optical device. An object of the present invention is to provide a vibration analysis method and apparatus.

[0010]

Means for Solving the Problems The above-mentioned problems are solved,
In order to achieve the object, a vibration analysis method for an optical device according to the present invention analyzes an influence of vibration of an optical component included in the optical device on the performance of the optical device under actual operating conditions of the optical device. A vibration analysis method for actually measuring the frequency and amplitude of the optical component; and a finite element method based on the measured information on the frequency and amplitude of the optical component. A numerical model generating step of generating a simulation model, a vibration calculating step of performing vibration calculation using the simulation model generated in the numerical model forming step, and a deformation state of the optical component calculated by the vibration calculated in the vibration calculating step Is approximated by a shape function capable of expressing a unique shape in a three-dimensional space; and And an optical calculation step of calculating characteristics related to the performance of the scientific instrument.

Further, in the vibration analysis method for an optical device according to the present invention, the numerical model creating step includes an allowable error specifying step for specifying an allowable error of an optical path, and an element selection for selecting a finite element in the simulation model. A vibration calculation by changing the material property and / or shape property of the selected finite element, and calculating the material property and / or shape property of the finite element with respect to the frequency and amplitude measured in the vibration measurement step. A sensitivity calculation step of examining the sensitivity, and a model optimization step of performing a convergence calculation by changing a material property and / or a shape property of a finite element based on the calculated sensitivity until the calculated value falls within the allowable error. It is characterized by.

In the method of analyzing vibration of an optical instrument according to the present invention, in the curved surface fitting step, the shape function is represented by a polynomial of spatial variables x, y, and z, and is discretely calculated by the simulation model. It is characterized in that the surface fitting is performed by obtaining each coefficient of the polynomial from the deformed state by the least square method.

In the vibration analysis method for an optical instrument according to the present invention, the curved surface fitting step includes an allowable value specifying step of specifying an allowable value of approximation accuracy of the curved surface by the polynomial, and an order of specifying an order of the polynomial. Specifying step, comparing the deformation amount of the optical component calculated by the polynomial and the measured deformation amount, if the difference is within the allowable value, adopts the polynomial defined in the order specifying step, the allowable A convergence calculation step of increasing the degree of the polynomial and calculating the degree until the value falls outside the allowable value.

Further, the vibration analyzing apparatus for an optical device according to the present invention is provided for analyzing the influence of the vibration of an optical component constituting the optical device on the performance of the optical device under actual operating conditions of the optical device. An apparatus for analyzing vibration of an optical device, comprising: a vibration measuring unit for actually measuring the frequency and amplitude of the optical component; and a simulation model of a finite element method based on the measured information on the frequency and amplitude of the optical component. Numerical model creating means for creating, a vibration calculating means for performing a vibration calculation using a simulation model generated by the numerical model creating means, and the deformation state of the optical component due to vibration calculated by the vibration calculating means, A curved surface fitting unit that approximates with a shape function capable of expressing a unique shape in a three-dimensional space; It is characterized by including the optical calculation means for performing calculation of characteristics relating to performance, the.

Further, in the vibration analyzing apparatus for optical equipment according to the present invention, the numerical model creating means includes an allowable error specifying means for specifying an allowable error of an optical path, and an element selecting means for selecting a finite element in the simulation model. Means for calculating a vibration by changing a material property and / or a shape property of the selected finite element, and calculating a material property and / or a shape property of the finite element with respect to a frequency and an amplitude measured by the vibration measuring means. A sensitivity calculating means for examining the sensitivity, and a model optimizing means for performing a convergence calculation by changing a material property and / or a shape property of a finite element based on the calculated sensitivity until the calculated value falls within the allowable error. It is characterized by.

Further, in the vibration analyzing apparatus for optical equipment according to the present invention, the curved surface fitting means expresses the shape function by a polynomial of spatial variables x, y, z, and is discretely calculated by the simulation model. It is characterized in that the surface fitting is performed by obtaining each coefficient of the polynomial from the deformed state by the least square method.

Further, in the vibration analyzing apparatus for optical equipment according to the present invention, the curved surface fitting means includes an allowable value specifying means for specifying an allowable value of approximation accuracy of the curved surface by the polynomial, and an order for specifying an order of the polynomial. Designating means, comparing the deformation of the optical component calculated by the polynomial and the measured deformation, and if the difference is within the allowable value, adopts the polynomial defined by the degree specifying means, A convergence calculation means for calculating by increasing the degree of the polynomial until the value falls outside the allowable value.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described.

First, an outline of an embodiment will be described.

The method for designing an optical device according to one embodiment is a method for analyzing the influence of the vibration of an optical component constituting the device on the performance of the optical device under actual use conditions of the optical device. A vibration measurement step of actually measuring the number and amplitude, a numerical model creation step of creating a simulation model of the finite element method from the measured vibration frequency and amplitude information of the optical component, and a numerical model creation step. A vibration calculation step of performing a vibration calculation using a simulation model; and a curved surface fitting for converting a vibration (deformation) state of the optical component calculated in the vibration calculation step into a shape function capable of expressing a unique shape in a three-dimensional space. And an optical calculation step of calculating an optical path trajectory and the like based on the shape function.

In this configuration, in the vibration measurement step, the damping effect for each frequency of each optical unit, which cannot be predicted only by numerical simulation such as the finite element method, is passed to the numerical model creation step. By defining the detailed shape of the optical unit using a finite element method model, it compensates for measurement points that would be insufficient due to physical problems such as sensor wiring in the equipment during measurement, and the actual vibration measurement in the vibration calculation process Then, the vibration component (especially rotation fluctuation) of the optical unit which is difficult to measure is accurately calculated, and in the curved surface fitting step, the vibration state of the optical surface calculated in the vibration calculation step is determined by the characteristics of the finite element method model, Is represented as spatial discrete point data, so that optical calculations at arbitrary positions can be performed based on the vibrational state at discrete points on the optical surface. Is converted to a shape function capable of expressing a unique shape for the optical calculation process and passed to the optical calculation process.In the optical calculation process, it is possible to calculate the optical path in consideration of the vibration mode of each optical surface. The arrangement of each optical unit can be determined by accurately considering the influence of the generated vibration deformation of the optical unit on the optical path.

Further, in the above numerical model creation step, an allowable error specifying step for specifying an allowable error of the optical path, an element selecting step for selecting a finite element in the model, a material property and a shape of the selected finite element A sensitivity calculation step of performing a vibration calculation by changing the characteristics, and examining the sensitivity of the material characteristics of the finite element to the measured frequency and amplitude, and the sensitivity of the shape characteristics,
A model optimization step of performing a convergence calculation by changing the material characteristics and shape characteristics of the finite element until the variation amount of the optical path falls within the allowable error based on the sensitivity.

According to this configuration, when the amount of fluctuation of the optical path becomes a problem due to vibration or the like generated during actual use of the product,
In the allowable error specifying step, the allowable amount of the optical path is specified, in the element selecting step, design variables that can determine the optical path are defined in the finite element model, and in the sensitivity calculating step, the design variables are defined in the element selecting step. The sensitivity coefficient for the variation of the optical path of the design variable obtained is obtained, and in the model optimization step, the sensitivity coefficient is extracted in the sensitivity calculation step until the variation amount of the optical path specified in the allowable error designation step falls within an allowable value. Among the design variables, the one with the higher sensitivity coefficient is preferentially operated, the vibration calculation is repeatedly performed, and the optimum design variable can be determined by the computer.

In the above-mentioned curved surface fitting step, the shape function is represented by a polynomial of spatial variables x, y, and z, and each coefficient of the polynomial is calculated by a least square method from a deformed state discretely calculated by a numerical model. And perform surface fitting.

With this configuration, the result of the vibration of the discrete optical surface only on the node of the finite element method model calculated in the vibration calculation step can be converted into any optical structure considered in the configuration of the optical unit in the optical calculation step. When converting to a curved surface equation to calculate the path, it is possible to represent various vibration states, and it is possible to reduce the error of the optical path calculation for local deformation of the optical surface .

In the above-mentioned curved surface fitting step, an allowable value specifying step of specifying an allowable value of the approximation accuracy of the curved surface, an order specifying step of specifying a polynomial order of the shape function, and a deformation of the optical component calculated by the polynomial Comparing the amount and the measured deformation amount, if the difference is within the allowable value, the polynomial defined in the order designation step is adopted, and if the difference is outside the allowable value, the polynomial order is reduced to within the allowable value. And a convergence calculation step of performing calculation.

According to this configuration, when the vibration result of the discrete optical surface is interpolated by the polynomial approximation in the curved surface fitting step, if the higher-order polynomial order is set unnecessarily for the vibration mode, the fitting accuracy is reduced. Can be prevented. Hereinafter, an embodiment of the present invention will be described with respect to an optical design of a laser scanner which is a writing device for an image forming unit of a copying machine.

FIG. 1 is a flowchart showing a procedure of a method for analyzing vibration of an optical apparatus according to an embodiment of the present invention.

In FIG. 1, first, the vibration of each optical unit is actually measured in a vibration measuring step (step S1).

FIG. 2 shows a laser scanner unit which is a writing device for an image forming section of a copying machine. The optical device includes a laser irradiation unit 2A and lens groups 2B and 2D.
, A polygon mirror 2C, a scanner unit 2G for holding the polygon mirror 2C, and a folding mirror 2E.

In the image forming process, a laser is first irradiated by a laser irradiation unit 2A based on a digital signal of an image, and is reflected by a rotating polygon mirror 2C via a lens 2B to perform scanning. The laser reflected by the polygon mirror 2C is corrected via the lens group 2D so that the scanning speed becomes uniform on the reflection surface of the return mirror 2E, and the laser reflected by the pushback mirror 2E finally becomes the photosensitive drum 2F. Irradiated on top. The photosensitive drum 2F rotates around its central axis, and forms an image by sending out an irradiation position in a direction perpendicular to the main scanning direction in which the image is scanned.

FIG. 3 is a diagram showing a specific configuration of the vibration measuring device used in the vibration measuring step (Step S1). As a measuring method, the piezoelectric acceleration sensor 3A is directly attached to each optical component when the product is operating, and the amplitude data for each frequency is collected by the FFT analyzer 3B. In addition, a modal test using an impact hammer was performed, and modal parameters (eigenfrequency, eigenmode,
Damping ratio). The collected experimental data is stored in a storage device 3D such as a hard disk in the computer 3C, and is passed to a numerical model creation step (Step S2).
The measured vibration state and modal parameters at the time of actual operation are displayed on a display device 3H connected to a computer, and the results of the collected vibration waveform data (3E), vibration mode (3F), modal parameters (3G), etc. Can be checked.

In the numerical model creation step (step S2), a finite element method model for calculating the vibration of the optical device is calculated in the vibration calculation step (step S3), and the laser generated when the equipment is vibrated in the optical calculation step (step S4). An optical surface for performing the optical calculation of the trajectory is defined.

FIG. 4 shows a numerical model creation process (step S
It is a figure which shows the specific operation | movement of the numerical model preparation apparatus used by 2). The storage device 3D stores a program for generating a finite element model, and defines a target of vibration calculation. The numerical model includes not only the folding mirror 2E and the scanner unit 2G, but also a frame 4B that holds these units, and covers a peripheral region that contributes to the vibration characteristics of the optical device. The created finite element method model is displayed on the display device 3H, and an optical surface 4D for determining an optical path is defined by a pointing device 4A such as a mouse. Material constants related to vibration characteristics (Young's modulus,
Poisson's ratio, mass density) are input and defined by the keyboard 4E, and at the same time, the damping ratio of the modal parameters measured in the vibration measurement step (step S1) is read from the storage device 3D, and the material definition for vibration calculation is obtained. Complete. Also, the vibration waveform of the excitation force applied to the optical device is read from the storage device 3D, and the pointing device 4
It is defined by designating a predetermined position in the numerical model by A.

In the vibration calculation step (step S3), a vibration analysis is performed by the finite element method using the numerical model created in the numerical model creation step (step S2).

FIG. 5 is a diagram showing the configuration and operation of the vibration calculation device used in the vibration calculation step (step S3). The vibration calculation step (S3) includes an eigenmode calculation step (step S31) and a frequency response calculation step (step S3).
2) and an eigenmode calculation step (step S3).
When 1) is completed, a vibration measuring step (step S1)
Eigenmode and eigenfrequency measured by the storage device 3D
And compares it with the eigenmode and eigenfrequency obtained by calculation on the display device 3H to confirm the validity of the numerical model. If the predetermined accuracy cannot be obtained, the process returns to the numerical model creation step (step S2) to correct the numerical model. When the predetermined accuracy is obtained, the process proceeds to the frequency response calculation step (step S32), the vibration is calculated, and the calculation result is displayed on the display device 3H. Here, the vibration mode at the time of actual operation measured in the vibration measurement step (step S1) is called as a wire frame model 5A including points and lines, and is superimposed on the calculation result 5B in the frequency response calculation step (step S32). Are performed, and the calculation accuracy is confirmed again (5C). If the predetermined accuracy cannot be obtained, the process returns to the numerical model creation step (step S2), and the excitation force or the damping ratio is adjusted. When the predetermined accuracy is obtained, the calculation result is stored in the storage device 3D, and the process proceeds to the optical calculation step (Step S4).

In this embodiment, in order to obtain the final vibration state of the optical apparatus, the frequency response analysis step (step S32) of calculating the vibration state on the frequency axis is employed. A transient response analysis for calculating the vibration state on the shaft may be adopted.

FIG. 6 is a diagram showing the configuration of the optical calculation step (step S4).

The optical calculation step (step S4) includes a curved surface fitting step (step S41) and an optical path calculation step (step S42).

The curved surface fitting step (step S4)
The operation in 1) will be described using an example of application to the optical surface of the folding mirror.

FIG. 7 is a vibration state diagram of the folding mirror obtained in the vibration calculation step. 2E shows the shape of the folding mirror at rest. The vibration state of the optical surface 7A calculated by the finite element method is a set of discrete point data obtained as a solution on the node 7B. Therefore, in order to calculate the optical path when the laser beam 7C scans the folding mirror 2E, the deformation state of the optical surface, which is discrete data, is converted into a continuous shape function, and the reflection angle at an arbitrary position is calculated. And so on. There are various methods of curved surface fitting for converting discrete deformation data into a continuous shape function. However, in the present embodiment, a shape function is used as a shape function in the present embodiment because of a simple calculation method in an optical path calculation step (step S42). The yz polynomial as defined in (1) is adopted.

[0042]

(Equation 1) In this polynomial, the coordinate system of the optical surface is selected on the yz plane as shown in FIG. FIG. 8 shows the coefficient C for each yz term in equation (1). A specific method of the curved surface fitting is that the node displacement vector X and the node coordinates yz of the optical surface obtained in the vibration calculation step (step S3) are called from the storage device, and the minimum 2
A coefficient group CN that minimizes the error with respect to equation (1) is obtained by the multiplication method. When performing fitting, the order of the polynomial order to be handled affects fitting accuracy. If the target order is too small, it is not possible to express a sufficient vibration shape, while if it is too large, an error due to higher-order effects will occur. Therefore, the result of the curved surface fitting on the optical surface and the result of the vibration calculation on the node are visualized by the display device as shown in FIG. 9 so that the state of the fitting can be confirmed. Further, it is possible to display the fitting error and the polynomial coefficient as shown in FIG.

If sufficient fitting accuracy is not obtained by the above processing, the process returns to the curved surface fitting step (step S41), and the polynomial degree in equation (1) is set again to perform fitting. If a high accuracy is obtained, the optical path calculation step (step S4)
Go to 2).

In the optical path calculation step (step S42), how the optical path of the laser beam changes due to the deformation of the optical surface is calculated, and the final irradiation position is obtained. The shape function f of the optical surface is obtained by equation (2). If the scalar vector of the laser beam applied to the folding mirror is S, the directional differential coefficient at the reflection position can be easily calculated by equation (3). The direction in which the beam is reflected by the oscillating optical surface and travels is determined.

[0045]

(Equation 2) Laser irradiation unit 2A and lens group 2 shown in FIG.
For the optical surfaces B, 2D, and the polygon mirror 2C, the same optical path calculation as that of the above-described folding mirror is performed, and the laser spot position finally irradiated on the photosensitive drum 2F is calculated. The calculated laser spot position can be confirmed by the image display device.

FIG. 11 shows an example of image output when a total of 16 straight lines corresponding to two rotations of the octagonal polygon mirror 2C are drawn on the photosensitive drum 2F when the apparatus is vibrated. Since the rotation speeds of the polygon mirror 2C and the photosensitive drum 2F are constant, 16 straight lines should actually be able to be drawn at equal intervals. However, it can be seen that the linear intervals are sparse due to the vibration of each optical surface. If the output image quality affected by the vibration is unacceptable, the process proceeds to the model optimization step (step S5).

FIG. 12 shows the detailed configuration of the model optimizing step (step S5) in the design flow of the optical equipment. The model optimization step (step S5) includes an allowable error designation step (step S51) and an element selection step (step S52).
And a sensitivity calculation step (step S53).

In the allowable error designating step (step S51), the allowable variation of the laser beam spot at a predetermined position in the design of the optical equipment is designated.

The operation in this step will be described below with reference to FIG. In the allowable error designating step (step S51), the finite element model created in the numerical model creating step (step S3) is displayed on the display device 3H, and the position at which the allowable variation amount of the laser beam spot during vibration is defined Is instructed by a pointing device or the like. At the same time, an allowable error amount is input. In the present embodiment, the allowable error amount is set to be 0.1 μm on the photosensitive drum 2F.

In the element selecting step (step S52), the sensitivity calculation step (step S52) determines the stiffness and mass density sensitivity of the components of the optical device with respect to the variation of the spot of the laser beam.
In the calculation in 53), selection of a component to be subjected to sensitivity calculation is defined by selecting an element group in the finite element model again.

The operation of this step will be described below with reference to FIG. In the present embodiment, rigidity (Young's modulus), which is a material characteristic of the mirror 14A, the mirror holder 14B, and the mounting spring 14C, which are the components of the folding mirror 2E, is selected as an object of the sensitivity calculation. When an element in the finite element model displayed on the display device 3H is selected by a pointing device or the like, all the same parts (the same material) are recognized as the sensitivity calculation target elements. This operation is repeated for each part, and the target element of the sensitivity calculation is defined. Also, the selected parts are displayed in a list on the display device 3H to facilitate confirmation.

In the sensitivity calculation step (step S53), the sensitivity to the spot variation of the material characteristics (the Young's modulus of the element in the present embodiment) of the component selected in the element selection step (step S52) is calculated. The sensitivity in the present embodiment is obtained by dividing the spot fluctuation amount of the laser beam by the increase / decrease ratio of the Young's modulus of the element. This means that the higher the sensitivity of the part, the more the change in the rigidity is more effective in suppressing the spot fluctuation amount.

The operation of this step will be described below with reference to FIG. The rigidity of the part selected in the element selection step (step S52) is increased (or decreased) by 10% uniformly, and the vibration calculation step (step S3) and the optical calculation step (S4) are performed, and the sensitivity of the part rigidity to the spot variation is performed. Is calculated.
In the present embodiment, it is 10%. However, if the change ratio is constant for each component, it is not necessary to be 10%. The calculated sensitivity results are color-coded for the elements in the finite element model according to the magnitude of the sensitivity value and are visualized on the display device 3H, so which component rigidity contributes to the spot variation amount of the laser beam. Can be easily determined. In this embodiment, the specification is such that the larger the sensitivity value, the warmer the color, and the mounting spring 14C has the highest sensitivity. As a result of the sensitivity calculation, a guide is made as to which one of the components constituting the optical apparatus should be focused on, and the process returns to the numerical model creation step (step S2) to reconstruct a specific countermeasure model. This operation is repeated until it falls within the allowable error specified in the allowable error specifying step (step S51).

As described above, according to the present embodiment, the following effects can be obtained.

In the vibration measuring step, the damping effect for each frequency of each optical unit, which cannot be predicted only by the numerical simulation such as the finite element method, is passed to the numerical model creating step. By defining the shape with a finite element method model, it compensates for measurement points that are insufficient due to physical problems such as wiring of sensors into the device in the measurement, and it is difficult to measure in the vibration calculation process with actual vibration measurement The vibration component (especially rotation fluctuation) of a simple optical unit is accurately calculated, and in the curved surface fitting process, the vibration state of the optical surface calculated by the vibration calculation process is spatially limited at the nodes due to the characteristics of the finite element method model. Since it is expressed as discrete point data, in order to perform optical calculation at an arbitrary position, a unique shape expression for a three-dimensional space based on the vibration state at discrete points on the optical surface For passing the optical calculations step by converting the ability shape function, the optical calculation process, it becomes possible to perform the calculation of the optical path of which the oscillation mode of each optical surface,
The arrangement of each optical unit can be determined by accurately considering the influence of the vibration deformation of the optical unit generated during actual operation on the optical path.

When the amount of fluctuation of the optical path becomes a problem due to vibration or the like generated during actual use of the product, the allowable amount of the optical path is specified in the allowable error specifying step, and the optical path is specified in the element selecting step. In the finite element model, the design variables that can determine the parameters are determined, and in the sensitivity calculation step, the sensitivity coefficient to the variation of the optical path of the design variables defined in the element selection step is obtained. Until the variation amount of the optical path specified in the error specification process falls within the allowable value, the design variable extracted in the sensitivity calculation process with the higher sensitivity coefficient is preferentially operated, and the vibration is calculated repeatedly. This makes it possible to determine optimal design variables.

The result of the vibration of the discrete optical surface only on the node of the finite element method model calculated in the vibration calculation step is used to calculate any optical path conceivable in the configuration of the optical unit in the optical calculation step. Therefore, when converting into an equation of a curved surface, it is possible to represent various vibration states, and it is possible to reduce the error of the optical path calculation for local deformation of the optical surface.

Further, in the curved surface fitting step, when the vibration results of the discrete optical surfaces are interpolated by the polynomial approximation, if the polynomial order of the vibration mode is set unnecessarily high, the fitting accuracy is reduced. Has the effect of preventing.

[0059]

As described above, according to the present invention, there is provided a method and apparatus for analyzing the vibration of an optical device which can accurately determine the influence of the vibration during the actual operation of the optical device on the performance of the optical device. It is possible to do.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a procedure of a vibration analysis method for an optical device according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram illustrating a configuration of a laser scanner unit.

FIG. 3 is an explanatory diagram showing a specific configuration and operation of the vibration measuring device.

FIG. 4 is an explanatory diagram showing the operation of the numerical model creation device.

FIG. 5 is an explanatory diagram showing a configuration example and operation of a vibration calculation device.

FIG. 6 is an explanatory diagram showing a configuration of an optical calculation step.

FIG. 7 is an explanatory diagram showing a vibration state of a return mirror obtained in a vibration analysis step.

FIG. 8 is an explanatory diagram of polynomial coefficients in curved surface fitting.

FIG. 9 is an explanatory diagram showing an operation in a curved surface fitting step.

FIG. 10 is an explanatory diagram showing an operation in a curved surface fitting step.

FIG. 11 is an explanatory diagram showing a calculation result in an optical calculation step.

FIG. 12 is an explanatory diagram showing a configuration of a model optimization step (step S5) in a design flow of an optical device.

FIG. 13 is an explanatory diagram showing an operation of an allowable error designation step.

FIG. 14 is an explanatory diagram showing an operation of an element selection step.

FIG. 15 is an explanatory diagram showing a result of a sensitivity calculation step.

[Explanation of symbols]

 2A laser irradiation unit 2B, 2D lens group 2C polygon mirror 2E folding mirror 2F photosensitive drum 2G scanner unit 3A piezoelectric acceleration sensor 3B FFT analyzer 3C computer 3D storage device 3E Vibration waveform data displayed on display device 3F Displayed on display device Vibration mode 3G Modal parameter displayed on 3G display device 3H Display device 4A Pointing device 4B Frame 4D Optical surface 4E Keyboard 5A Measured actual operation mode wireframe 5B Calculated actual operation mode FEM model 5C Display device Actual operation mode displayed 7A Optical surface 7B Vibration optical surface 7C Laser beam 14A Mirror 14B Mirror holder 14C Mounting spring

Claims (8)

[Claims] 1. A vibration analysis method for an optical device for analyzing the influence of the vibration of an optical component constituting the optical device on the performance of the optical device in an actual operation state of the optical device, the method comprising: A vibration measuring step of actually measuring the frequency and amplitude of the component; a numerical model creating step of creating a simulation model of the finite element method based on the measured information of the frequency and amplitude of the optical component; A vibration calculation step of performing a vibration calculation using the simulation model generated in the creation step; and a shape capable of expressing a deformation state due to the vibration of the optical component calculated in the vibration calculation step in a three-dimensional space. A curved surface fitting step approximating with a function, and an optical calculation for calculating characteristics related to the performance of the optical device based on the shape function Vibration analysis method of the optical apparatus characterized by comprising the extent, the. 2. The numerical model creating step includes: a tolerance specifying step of designating a tolerance of an optical path; an element selecting step of selecting a finite element in the simulation model; A sensitivity calculation step of performing a vibration calculation by changing the shape characteristics, and examining the sensitivity of the material characteristics and / or the shape characteristics of the finite element to the frequency and amplitude measured in the vibration measurement step; The optical apparatus according to claim 1, further comprising: a model optimization step of performing a convergence calculation by changing a material property and / or a shape property of a finite element until the finite element falls within the allowable error. Vibration analysis method. 3. In the curved surface fitting step, the shape function is represented by a polynomial of spatial variables x, y, z, and each coefficient of the polynomial is calculated by a least square method from a deformation state discretely calculated by the simulation model. 2. The method for analyzing vibration of an optical device according to claim 1, wherein a curved surface fitting is performed by calculating the following equation. 4. The curved surface fitting step includes a tolerance value designation step of designating a tolerance value of approximation accuracy of the curved surface by the polynomial, a degree designation step of designating an order of the polynomial, and an optical component calculated by the polynomial. The deformation amount is compared with the measured deformation amount, and if the difference is within the allowable value, the polynomial defined in the degree designation step is adopted. 4. The method according to claim 3, further comprising a convergence calculation step of calculating by increasing the degree of the polynomial. 5. An apparatus for analyzing vibration of an optical device for analyzing the influence of the vibration of an optical component constituting the optical device on the performance of the optical device in an actual operation state of the optical device, wherein: Vibration measurement means for actually measuring the frequency and amplitude of the component; numerical model creation means for creating a simulation model of the finite element method based on the measured information on the frequency and amplitude of the optical component; Vibration calculating means for calculating vibration using the simulation model generated by the generating means; and a shape capable of expressing a deformation state of the optical component due to vibration calculated by the vibration calculating means in a three-dimensional space. Curved surface fitting means approximating with a function, and optical calculation means for calculating characteristics related to the performance of the optical device based on the shape function , Vibration analyzer of an optical instrument, characterized by comprising. 6. The numerical model creating means includes a tolerance designating means for designating a tolerance of an optical path, an element selecting means for selecting a finite element in the simulation model, a material property of the selected finite element, And / or sensitivity calculation means for performing a vibration calculation by changing the shape characteristic and examining the sensitivity of the material property and / or shape property of the finite element to the frequency and amplitude measured by the vibration measurement means; 6. An optical apparatus according to claim 5, further comprising: a model optimizing unit that changes a material property and / or a shape property of a finite element and performs a convergence calculation until the finite element falls within the allowable error. Vibration analysis equipment. 7. The surface fitting means expresses the shape function by a polynomial of spatial variables x, y, z, and calculates each coefficient of the polynomial by a least square method from a deformation state discretely calculated by the simulation model. 6. A curved surface fitting is performed by calculating
A vibration analysis device for an optical device according to item 1. 8. The surface fitting unit includes: a tolerance designating unit that designates a tolerance of approximation accuracy of a curved surface by the polynomial; an order designating unit that designates an order of the polynomial; and an optical component calculated by the polynomial. The deformation amount is compared with the measured deformation amount, and if the difference is within the allowable value, the polynomial defined by the degree designation means is adopted. The apparatus according to claim 7, further comprising: a convergence calculation unit configured to calculate by increasing a degree of the polynomial.