JP5152074B2 - Drive signal generator, optical scanning device including the same, and image display device - Google Patents

Description

  The present invention relates to a drive signal generator, an optical scanning device including the drive signal generator, and an image display device, and more particularly to a drive signal for forcibly driving a reflection mirror of an optical scanning element in a non-resonant mode. The present invention relates to a drive signal generator that generates a drive signal obtained by performing notch filter processing on a basic waveform for generating a signal, an optical scanning device including the drive signal, and an image display device.

  Conventionally, an optical scanning device that scans light using an optical scanning element such as a galvanometer mirror is known.

  As an image display device using this optical scanning device, for example, optical scanning that displays an image by two-dimensionally scanning laser light (hereinafter also referred to as “image light”) generated based on an image signal by the optical scanning device. A type image display apparatus is known.

  In this type of optical scanning type image display device, image light is scanned in the horizontal direction by the reflecting mirror of the first optical scanning element, and scanned in the vertical direction by the reflecting mirror of the second optical scanning element, whereby an image is obtained. Is displayed.

  For example, in the image display device described in Patent Document 1 below, image light is reciprocated in the horizontal direction by oscillating the reflection mirror of the first optical scanning element in the resonance mode, and reflected by the second optical scanning element. Image light is scanned in the vertical direction by driving the mirror in a non-resonant mode in a sawtooth shape.

  The scanning in the vertical direction is performed by driving the reflection mirror of the optical scanning element in a sawtooth shape like this, but the reflection mirror of the optical scanning element can be swung to a fixed member via an elastic beam member. Therefore, there is a specific resonance frequency determined by the reflecting mirror and the beam member.

  Therefore, if the signal waveform for driving the reflection mirror of the optical scanning element includes a resonance frequency unique to the optical scanning element, resonance vibration occurs in the optical scanning element. This resonance vibration causes a high-frequency component (ringing component) to be superimposed on the swing of the reflecting mirror, resulting in a situation where optical scanning cannot be performed properly (see FIG. 11).

  Therefore, in the conventional optical scanning device and image display device, a driving signal for forcibly driving the reflection mirror of the optical scanning element in the non-resonant mode is a sawtooth waveform (hereinafter referred to as “saw waveform”). ) By generating a drive signal obtained by filtering the signal using a notch filter or the like (see Patent Document 2), resonance vibration is suppressed.

JP 2006-276399 A JP 2004-361920 A

  However, when generating a drive signal in which the resonance frequency component of the optical scanning element is reduced using the notch filter, it is necessary to adjust the sharpness Q (Quality factor) of the attenuation region in the notch filter, and the adjustment takes time. It will take.

  Therefore, the present invention can rapidly adjust the sharpness Q of the notch filter when generating a drive signal for forcibly driving the reflecting mirror of the optical scanning element in the non-resonant mode using the notch filter. It is an object of the present invention to provide a drive signal generator, an optical scanning device including the drive signal generator, and an image display device.

  According to a first aspect of the present invention, there is provided a basic waveform storage means for storing basic waveform signal data for generating a periodic drive signal, the basic waveform signal data is read from the basic waveform storage means, and the basic waveform is read out. Filter means for performing notch filter processing on the signal to generate a drive waveform signal, drive waveform storage means for storing data of the drive waveform signal generated by the filter means, and data of the drive waveform signal for the drive waveform storage means Drive signal generating means for generating the drive signal by reading out from analog and converting the analog signal into a drive signal generator, and forcibly swinging the reflection mirror of the optical scanning element in a non-resonant mode by the drive signal. Ringing generated by the natural resonance of the optical scanning element when the reflection mirror is swung by the drive processing means. Ringing detection means for detecting the phase of the ring, and filter characteristic adjustment means for adjusting the sharpness of the attenuation region in the notch filter according to the phase of the ringing detected by the ringing detection means, To do.

  According to a second aspect of the present invention, in the drive signal generator according to the first aspect, the filter characteristic adjusting means is based on a ringing frequency detected by the ringing detecting means in the center frequency of the attenuation region in the notch filter. When the sharpness of the attenuation region in the notch filter is changed with the setting being high, the sharpness is decreased when the ringing phase is delayed, and the sharpness is increased when the ringing phase is advanced. It is characterized by.

  According to a third aspect of the present invention, in the drive signal generator according to the first or second aspect, the filter characteristic adjusting means is a ringing detector in which the ringing detecting means detects the center frequency of the attenuation region in the notch filter. When the sharpness of the attenuation region in the notch filter is changed with the frequency set lower than the frequency, the sharpness is increased when the ringing phase is delayed, and the sharpness is decreased when the ringing phase is advanced. It is characterized by making it.

  According to a fourth aspect of the present invention, in the drive signal generator according to any one of the first to third aspects, the ringing detection unit detects a frequency of the ringing, and the filter characteristic adjustment unit includes: The sharpness of the attenuation region in the notch filter is adjusted according to the phase and frequency of the ringing detected by the ringing detection means.

  According to a fifth aspect of the present invention, in the drive signal generator according to any one of the first to fourth aspects of the present invention, the filter characteristic adjusting means is configured to swing the reflection mirror of the optical scanning element while swinging the reflection mirror. The sharpness of the attenuation region in the notch filter is adjusted.

  According to a sixth aspect of the present invention, in the drive signal generator according to any one of the first to fourth aspects, the filter characteristic adjusting means is configured to start the oscillation of the reflection mirror of the optical scanning element. The sharpness of the notch filter attenuation region is adjusted.

Moreover, the invention which concerns on Claim 7 is provided with the operation means for starting adjustment of the sharpness of the attenuation range in the said notch filter in the drive signal generator of any one of Claims 1-4,
The filter characteristic adjusting means adjusts the sharpness of the attenuation region in the notch filter when the operating means is operated.

  According to an eighth aspect of the present invention, there is provided the optical scanning element and the drive signal generator according to any one of the first to seventh aspects, and a light emitting unit that emits a laser beam to be scanned by the optical scanning element. It was set as the optical scanning device provided with these.

  The invention according to claim 9 is a light emitting unit that emits image light having an intensity corresponding to an image signal, and the optical scanning element and the drive signal generator according to any one of claims 1 to 7. A second optical scanning element that scans light in a direction that intersects a scanning direction of the optical scanning element, and a second drive unit that generates a second drive signal that drives the second optical scanning element, The image display apparatus is characterized in that the image light is displayed two-dimensionally by the optical scanning element and the second optical scanning element.

  According to a tenth aspect of the present invention, in the image display device according to the ninth aspect, the image light scanned by the optical scanning element and the second optical scanning element is projected onto the retina of at least one eye of the user. An eyepiece optical system is provided.

  According to the present invention, when the drive signal for forcibly driving the reflection mirror of the optical scanning element in the non-resonant mode is generated using the notch filter, the sharpness Q of the attenuation region in the notch filter is rapidly adjusted. be able to.

It is explanatory drawing which shows the structure of an optical scanning device. It is a figure which shows the waveform of the drive signal which the drive signal generator of an optical scanning device outputs. It is a figure for demonstrating the production | generation method of a drive signal. It is a figure for demonstrating the production | generation method of a drive signal. It is a figure which shows the change of a ringing waveform when changing sharpness in the notch filter set to the center frequency lower than an optimal frequency. It is a figure which shows the change of a ringing waveform when the sharpness is changed in the notch filter set to the center frequency higher than the optimal frequency. It is a figure which shows the flow of a sharpness adjustment process. It is explanatory drawing which shows the structure of a retinal scanning display. It is operation | movement explanatory drawing of the scanning part of a retinal scanning display. It is a block diagram of the vertical drive signal generator in a retinal scanning display. It is a figure which shows the ringing waveform which generate | occur | produces by the resonance intrinsic | native to an optical scanning element.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following description, an example in which the embodiment of the drive signal generator of the present invention is applied to an optical scanning device and an image display device will be described.

[1. Optical scanning device]
First, an example in which the drive signal generator of the present invention is applied to an optical scanning device will be described.

  As shown in FIG. 1, the optical scanning device 1 controls the entire optical scanning device 1 and outputs a drive signal Sa corresponding to the image signal S, and a drive signal output from the control unit 2. A light emitting unit 3 that emits laser light (image light) corresponding to the image signal S based on Sa, an optical scanning unit 4 that scans the laser light emitted from the light emitting unit 3, and an operation that can be operated by the user Part 7.

  The optical scanning unit 4 includes an optical scanning element 5 (deflection element) such as a galvano mirror, a drive signal generator 6 that generates a drive signal S1 for driving the optical scanning element 5, and the like. It operates based on input control signals (synchronization signal, parameter adjustment signal, ON / OFF signal, etc.). The optical scanning element 5 can forcibly oscillate (rotate) its reflection mirror 5a (deflection surface) in a non-resonant mode so as to scan the laser light emitted from the light emitting unit 3. Any driving method such as piezoelectric driving, electromagnetic driving, or electrostatic driving may be used.

(Configuration of the drive signal generator 6)
The drive signal generator 6 is a drive signal for forcibly driving the reflection mirror 5a of the optical scanning element 5 in a non-resonant mode, and performs a notch filter process on a basic waveform signal for generating a periodic drive signal. The drive signal S1 having a sawtooth waveform is generated and configured as follows. As shown in FIG. 2, the drive signal S1 is a signal having a sufficiently short period of transition from the maximum level to the minimum level compared to the period of transition from the minimum level to the maximum level. The basic waveform signal is generated by performing a low-pass filter process (see FIG. 3B) on a sawtooth waveform signal that changes linearly (see FIG. 3A). In the present embodiment, the sawtooth drive signal S1 has a waveform as shown in FIG. 3C, but is not limited thereto, and has a substantially linear slope such as a triangular wave, a trapezoidal wave, or a sine wave. The present invention can also be applied to a waveform having periodicity.

  As shown in FIG. 1, the drive signal generator 6 includes a drive processing unit 10, a basic waveform storage unit 11, a filter unit 12, a filter characteristic adjustment unit 13, a ringing detection unit 14, a drive waveform storage unit 15, and a drive signal generation. A portion 16 is provided.

  The basic waveform storage unit 11 stores in advance data of a basic waveform signal S11 obtained by performing low-pass filter processing on the sawtooth waveform signal S10 that changes linearly. For example, as shown in FIG. 3, a basic waveform signal S11 is generated by performing a filtering process using an 18th-order low-pass filter on a sawtooth waveform signal S10 that changes linearly (see FIG. 3A). Data obtained by sampling the signal S11 at a predetermined sampling frequency and performing A / D conversion is stored in advance in the basic waveform storage unit 11 as data of the basic waveform signal S11.

  For example, if the primary resonance is f1 [Hz] and the second or higher resonance is f2 [Hz] or higher as resonance characteristics inherent to the optical scanning element 5, this low-pass filter processing is f2 (> f1) [Hz]. By attenuating the above frequencies, the influence of secondary or higher order resonance among the resonance characteristics unique to the optical scanning element 5 is suppressed.

  The filter unit 12 receives the data of the basic waveform signal S11 read from the basic waveform storage unit 11 by the drive processing unit 10, and performs low-pass filter processing with a predetermined parameter on the basic waveform signal S11 as shown in FIG. A drive waveform signal S12 is generated by performing notch filter processing.

  For example, if the resonance characteristic unique to the optical scanning element 5 is that the primary resonance is f1 [Hz], and the second-order resonance or more is f2 [Hz] or more, this notch filter processing has a frequency of f1 [Hz]. By attenuating as the center, the influence of the primary resonance among the resonance characteristics unique to the optical scanning element 5 is suppressed.

  Here, the filter processing by the secondary notch filter is realized by performing the calculation according to the following (Equation 1). Since this notch filter process cannot be performed unless the numerator order is equal to or higher than the denominator order, the filter unit 12 adds a second order notch filter process to a second order as shown in FIG. Low pass filter processing is performed. Therefore, the drive waveform signal S12 is a signal obtained by performing the 20th-order low-pass filter and the second-order notch filter processing on the sawtooth waveform signal S10.

  As described above, since the primary resonance of the optical scanning element 5 is suppressed by the secondary notch filter processing, the cut-off frequency of the low-pass filter is less than or equal to f1 [Hz], so that the drive signal S1 Linearity can be improved.

  Here, parameters used in the filter unit 12 are determined by the filter characteristic adjustment unit 13 and input to the filter unit 12. The parameters adjusted by the filter characteristic adjusting unit 13 are the center frequency fo and the sharpness Q (Quality Factor) in the attenuation region of the notch filter 12a. The processing operation of the filter characteristic adjusting unit 13 will be described in detail later.

  When the filter unit 12 generates the drive waveform signal S12 by performing the notch filter process and the low-pass filter process on the basic waveform signal S11 as described above, the data of the drive waveform signal S12 is stored in the drive waveform storage unit 15.

  The drive signal generator 16 receives the data of the drive waveform signal S12 read by the drive processor 10 from the drive waveform storage 15 with the clock CLK having a predetermined frequency, and converts it into an analog signal by the internal D / A converter 15a. As a result, the drive signal S1 is generated. The drive signal generation unit 16 inputs the generated drive signal S1 to the optical scanning element 5, and forcibly drives the reflection mirror 5a of the optical scanning element 5 in the non-resonant mode.

  The optical scanning device 1 scans the light emitted from the light emitting unit 3 according to the image signal S by the reflection mirror 5 a of the optical scanning element 5. The drive processing unit 10 reads the sawtooth waveform signal S10 from the basic waveform storage unit 11 and repeats the process of generating the drive signal S1 by the drive signal generation unit 16, thereby generating the drive signal S1 having the sawtooth waveform. The light output from the light emitting unit 3 is continuously scanned by the optical scanning element 5 in a predetermined direction.

  As described above, in the optical scanning device 1 according to the present embodiment, the driving signal S1 forcibly drives the reflection mirror 5a of the optical scanning element 5 in the non-resonant mode, and the sawtooth waveform signal S10 is subjected to low-pass filtering and notch filtering. A drive signal generator 6 that generates the processed drive signal S1 is provided.

  In particular, the drive signal generator 6 stores in advance the basic waveform signal S11 obtained by performing low-pass filter processing on the sawtooth waveform signal S10 in the basic waveform storage unit 11, and the basic waveform signal S11 is subjected to notch filter processing and Low-pass filter processing is performed to generate a drive waveform signal S12.

  Therefore, the calculation time of the low-pass filter processing by the drive signal generator 6 can be omitted or reduced. In particular, it is possible to omit or reduce the enormous calculation time required when performing high-order low-pass filter processing (for example, the above-described 20th-order low-pass filter processing).

  In addition, the filter unit 12 performs notch filter processing with the parameters adjusted by the filter characteristic adjustment unit 13 to generate the basic waveform signal S11. Thereby, the notch filter process in which the parameter needs to be changed as compared with the low-pass filter process can be performed with the parameter changed as necessary. In addition, by setting the parameter determined by the filter characteristic adjustment unit 13 as a parameter corresponding to the resonance characteristic specific to the optical scanning element 5, even when there is an individual difference in the resonance frequency specific to the optical scanning element 5, it is possible to cope with it. It becomes.

  By performing the notch filter processing by the filter unit 12, it is possible to reduce the storage capacity. That is, when the data subjected to the low-pass filter processing and the notch filter processing are stored in the storage means in advance, a plurality of data subjected to the notch filter processing with different parameters are required. However, in the present embodiment, since the notch filter process is performed when the drive signal S1 is generated, the amount of data stored in the storage unit can be reduced.

  Thus, in the drive signal generator 6 according to the present embodiment, the filter unit 12 performs notch filter processing, and the filter characteristic adjustment unit 13 adjusts the parameters of the notch filter 12a. The parameter determination method will be described in detail.

(Operation Principle of Filter Characteristic Adjustment Unit 13)
First, the principle of the parameter determination method for the notch filter 12a in the filter characteristic adjustment unit 13 will be described.

  First, the parameters of the notch filter 12a that generates the drive signal S1 that can reduce the ringing (resonance vibration) that occurs in the optical scanning element 5 are the following: the attenuation center frequency fo is 898 [Hz], and the sharpness Q is 39. Suppose that. Note that the ringing (resonance vibration) generated in the optical scanning element 5 can be minimized by setting the center frequency fo of the attenuation region to be the same as or close to the resonance frequency f1 unique to the optical scanning element 5.

  The center frequency fo of the attenuation region in the notch filter 12a is set to 896 [Hz] which is 2 [Hz] lower than the optimal value 898 [Hz] (hereinafter also referred to as “optimum value fa”), and the sharpness Q of the attenuation region As shown in FIG. 5, the ringing waveform generated in the reflection mirror 5a of the optical scanning element 5 is changed as shown in FIG.

  From this result, when the center frequency fo is lower than the optimum value fa, if the sharpness Q of the attenuation region is smaller than the optimum value 39 (hereinafter also referred to as “optimum value Qa”), the phase of the ringing waveform is delayed. It has been found that when the sharpness Q of the attenuation region is larger than the optimum value Qa, the phase of the ringing waveform advances.

  Further, when the center frequency fo of the attenuation region in the notch filter 12a is set to 900 [Hz] that is 2 [Hz] higher than the optimum value 898 [Hz], and the sharpness Q of the attenuation region is changed to 33, 39, and 45, light is obtained. The ringing waveform generated in the reflection mirror 5a of the scanning element 5 changed as shown in FIG.

  From these results, when the center frequency fo of the attenuation region is higher than the optimum value fa, the phase advances when the sharpness Q of the attenuation region is smaller than the optimum value 39 (hereinafter also referred to as “optimum value Qa”). It has been found that the phase is delayed when the sharpness Q of the attenuation region is larger than the optimum value Qa.

From the above, the relationship between the center frequency fo and sharpness Q of the attenuation region in the notch filter 12a and the drive waveform signal S12 can be summarized as follows.

  Therefore, the drive signal generator 6 according to the present embodiment compares the primary resonance frequency f1 unique to the optical scanning element 5 with the center frequency fo of the attenuation region in the notch filter 12a, and further detects the phase of ringing, Based on the phase, the sharpness Q of the attenuation region in the notch filter 12a is adjusted. The center frequency fo of the attenuation region in the notch filter 12a is adjusted by detecting the ringing frequency (hereinafter referred to as “ringing frequency fg”) and matching the ringing frequency fg with the frequency.

  Hereinafter, a method for adjusting the parameters (sharpness Q and center frequency fo) of the notch filter 12a will be specifically described with reference to FIG.

  First, the drive processing unit 10 controls the filter characteristic adjustment unit 13 to set the sharpness Q of the attenuation region and the center frequency fo in the notch filter 12a of the filter unit 12 to arbitrary Qx and fx (step S31). The center frequency fx is set to the drive processing unit 10 when the resonance frequency range specific to the optical scanning element 5 is known to some extent in advance, and a frequency lower or higher than the range is set. It is desirable to choose. When this parameter adjustment process has already been performed, it is desirable to store the ringing frequency fg at that time in the drive processing unit 10 and select a frequency lower or higher than the ringing frequency fg. By doing in this way, it can avoid that the center frequency fx set to the notch filter 12a corresponds with the ringing frequency fo.

  Next, the drive processing unit 10 drives the optical scanning element 5. That is, the drive processing unit 10 controls the basic waveform storage unit 11, the filter unit 12, the drive waveform storage unit 15, and the drive signal generation unit 16, and outputs the drive signal S 1 from the drive signal generation unit 16 to the optical scanning element 5. (Step S32).

  The specific operation in step S32 is as follows. First, the drive processing unit 10 reads the basic waveform signal S11 from the basic waveform storage unit 11 and inputs it to the filter unit 12. The filter unit 12 generates a drive waveform signal S12 obtained by performing notch filter processing and low-pass filter processing on the basic waveform signal S11. The drive processing unit 10 stores data of the drive waveform signal S12 in the drive waveform storage unit 15. At this time, the filter unit 12 executes notch filter processing with the sharpness Qx and the center frequency fx set in step S31. The drive processing unit 10 reads out the data of the drive waveform signal S12 stored in the drive waveform storage unit 15 with a predetermined clock and inputs it to the drive signal generation unit 16. The drive signal generation unit 16 generates a periodic drive signal S1 by repeatedly converting the data of the drive waveform signal S12 to analog, and drives the optical scanning element 5.

  After starting the driving of the optical scanning element 5 in this way, the ringing detection unit 14 detects the ringing state of the optical scanning element 5 (step S33). That is, the ringing detection unit 14 acquires a swing waveform of the reflection mirror 5a of the optical scanning element 5, extracts a ringing waveform included in the swing waveform by bandpass filter processing or the like, and stores the ringing waveform in an internal storage. Store in the department. Further, the ringing detection unit 14 detects a ringing frequency fg that is a frequency of the extracted ringing waveform, and outputs information on the detected ringing frequency fg to the filter characteristic adjustment unit 13. The swinging state of the reflection mirror 5a is detected by, for example, detecting the displacement of the beam member that drives the reflection mirror 5a with a piezoelectric element and the like, and detecting the voltage generated by the piezoelectric element with the ringing detection unit 14. It can be carried out. Further, the reflection mirror 5a is attached by attaching an electrode to the bottom of the reflection mirror 5a and the like, and attaching the electrode to the main body of the optical scanning element 5 facing the electrode so as to detect the capacitance generated between these electrodes. The swing waveform S20 may be acquired.

  Next, the drive processing unit 10 controls the filter characteristic adjusting unit 13 to change the value of the sharpness Qx set in the filter unit 12 (step S34). That is, the drive processing unit 10 performs a process of increasing or decreasing the sharpness Qx set in the filter unit 12.

  After starting the driving of the optical scanning element 5 with the drive signal S1 based on the drive waveform signal S12 filtered by the filter unit 12 in which the value of the sharpness Qx set in the filter unit 12 is changed in this way, the ringing detection unit 14 detects the ringing state of the optical scanning element 5 (step S35). That is, the ringing detection unit 14 extracts the ringing waveform included in the oscillation waveform of the reflection mirror 5a and stores it in the internal storage unit, and detects the ringing frequency fg to adjust the filter characteristics, as in the process of step S33. To the unit 13. Further, the ringing detection unit 14 compares the ringing waveform previously stored in the internal storage unit with the ringing waveform stored this time, detects a phase change of the ringing, and detects information on the phase change of the ringing as a filter characteristic adjustment unit 13 to output. This "ringing phase change information" is information on whether the phase of the current ringing waveform is advanced or delayed compared to the previous ring waveform and information on the phase difference.

  When the information about the ringing frequency fg is input from the ringing detection unit 14, the filter characteristic adjustment unit 13 compares the ringing frequency fg with the center frequency fx set in the filter unit 12. Then, it is determined whether the center frequency fx is higher or lower than the ringing frequency fg (step S36).

  In this process, when it is determined that the center frequency fx is higher than the ringing frequency fg, the filter characteristic adjustment unit 13 determines whether the phase of the current ringing waveform is advanced or delayed with respect to the previous ringing waveform (step) S37). This determination is made based on the information on the phase change of the ringing notified from the ringing detection unit 14.

  When determining that the phase of the current ringing waveform is delayed with respect to the previous ringing waveform, the filter characteristic adjusting unit 13 decreases the value of the sharpness Qx set in the filter unit 12 (step S40). On the other hand, if it is determined that the phase of the current ringing waveform is advanced, the filter characteristic adjustment unit 13 increases the value of the sharpness Qx set in the filter unit 12 (step S38). Note that the amount of increase when sharpness Qx is increased and the amount of decrease when sharpness Qx is decreased are predetermined set values. For example, if the set value is “1”, the amount of increase / decrease is “1” when the sharpness Q is “45”. The increase / decrease amount may be changed according to the magnitude of the phase difference of the ringing output from the ringing detection unit 14 instead of using a fixed value.

  If it is determined in step S36 that the center frequency fx is lower than the ringing frequency fg, the filter characteristic adjustment unit 13 advances the phase of the current ringing waveform with respect to the previous ringing waveform in the same manner as in step S37. It is determined whether it is late or late (step S39).

  If the filter characteristic adjustment unit 13 determines that the phase of the current ringing waveform is delayed with respect to the previous ringing waveform, the filter characteristic adjustment unit 13 increases the value of the sharpness Qx set in the filter unit 12 (step S38). On the other hand, if it is determined that the phase of the current ringing waveform is advanced, the filter characteristic adjustment unit 13 decreases the value of the sharpness Qx set in the filter unit 12 (step S40).

  When the processes of steps S38 and S40 are completed, the drive processing unit 10 determines whether or not the amplitude of the current ringing waveform is within a predetermined range (step S41). When the ringing detection unit 14 acquires a ringing waveform, the ringing detection unit 14 is configured to output amplitude information of the ringing waveform to the drive processing unit 10, and the drive processing unit 10 is based on this amplitude information. Then, it is determined whether or not the amplitude of the current ringing waveform is within a predetermined range.

  If it is determined that the amplitude of the current ringing waveform is within the predetermined range (step S41: YES), the drive processing unit 10 matches the center frequency fx set in the filter unit 12 with the ringing frequency fg (step S42). The parameter adjustment process is terminated. On the other hand, when it is determined that the amplitude of the current ringing waveform is not within the predetermined range (step S41: NO), the drive processing unit 10 repeats the processing from step S35.

  As described above, in the drive signal generator 6 according to the present embodiment, the primary resonance frequency f1 unique to the optical scanning element 5 is compared with the center frequency fo of the attenuation region in the notch filter 12a, and the phase of ringing is detected. Based on the phase, the sharpness Q of the attenuation region in the notch filter 12a is adjusted to the optimum value Qa. Further, the center frequency fo of the attenuation region in the notch filter 12a is adjusted to be the optimum value fa by adjusting the ringing frequency fg so as to coincide with the frequency.

  Therefore, when the driving signal S1 for forcibly driving the reflecting mirror of the optical scanning element in the non-resonant mode is generated using the notch filter, the brute force method (the value of the center frequency fo and the value of the sharpness Q are calculated). Compared with the method of detecting the ringing waveform for each of the drive signals S1 generated with various values and setting the optimum parameters, the parameters of the notch filter can be determined at high speed.

  Further, since the filter characteristic adjustment unit 13 dynamically determines the parameters of the notch filter 12a according to the characteristics of the optical scanning element 5, the optical scanning apparatus 1 is produced when the optical scanning element 5 is replaced by repair or the like. The work at the time can be easily performed.

  This parameter adjustment process is performed at the start of scanning of the laser beam. That is, the drive processing unit 10 controls the filter characteristic adjusting unit 13 before the laser beam emitted from the light emitting unit 3 is scanned by the optical scanning element 5 and when the reflection mirror 5a of the optical scanning element 5 starts to swing. Parameter adjustment processing is executed. With this operation, the accuracy of scanning of the laser beam by the optical scanning element 5 can be improved from the start of the scanning.

  The parameter adjustment process may be executed when a predetermined operation is performed on the operation unit 7. By executing parameter adjustment processing as necessary, it is possible to suppress power consumption, and to prevent ringing from being affected during scanning of laser light.

  This parameter adjustment processing can also be periodically executed while the laser beam emitted from the light emitting unit 3 is scanned by the optical scanning element 5. However, this parameter adjustment processing is executed at the start of scanning of the laser beam, and ringing waveform information is stored in the storage unit in the ringing detection unit 14, and the laser beam is scanned by the optical scanning element 5 in steps S 35 to S 35. It is desirable to execute the processing up to S41. With this operation, even if the resonance frequency inherent to the optical scanning element 5 changes due to a change in ambient temperature or continuous driving of the optical scanning element 5, the ringing waveform of the optical scanning element 5 continues to be in a predetermined range. The scanning accuracy of the laser beam by the optical scanning element 5 can be improved.

[2. Image display device]
Next, an example in which the drive signal generator of the present invention is applied to an image display device will be described. Here, a retinal scanning display will be described as an example of an image display device. This retinal scanning display is an image display device that projects scanned image light onto the retina of at least one eye of the user to allow the user to visually recognize the image.

  In the retinal scanning display 100 according to the present embodiment, a vertical drive signal generator 93 to be described later corresponds to the drive signal generator 6 described above and performs the same operation. After describing the schematic configuration, the operation will be described with the vertical drive signal generator 93 as the center.

(Schematic configuration of the retina scanning display 100)
As shown in FIG. 8, the retinal scanning display 100 includes a signal supply circuit 18, a light emitting unit 20, a scanning unit 30, an operation unit 40, an optical fiber cable 50, and a half mirror 31. The

  Based on the image signal S, the signal supply circuit 18 generates each signal, which is an element for forming an image, in units of pixels. That is, the signal supply circuit 18 generates and outputs an R (red) drive signal 60r, a G (green) drive signal 60g, and a B (blue) drive signal 60b based on the image signal S, and the signal supply circuit. 18 outputs a horizontal control signal 61 for controlling the horizontal scanning unit 80 and a vertical control signal 62 for controlling the vertical scanning unit 90, respectively.

  The light emitting unit 20 emits laser light (hereinafter also referred to as “image light”) that is intensity-modulated in accordance with a signal output from the signal supply circuit 18. Specifically, the R laser driver 66, the G laser driver 67, and the B laser driver 68 cause the R laser 63, the G laser 64, and the B laser 65 to emit laser beams having intensities corresponding to the drive signals 60r, 60g, and 60b. . Laser light emitted from each laser 63, 64, 65 is collimated into parallel light by collimating optical systems 71, 72, 73, and each laser light is selectively reflected and transmitted with respect to wavelength by dichroic mirrors 74, 75, 76. Then, it reaches the coupling optical system 77, and is collected and emitted to the optical fiber cable 50.

  In the scanning unit 30, the laser beam emitted from the light emitting unit 20 is two-dimensionally scanned. Specifically, the laser light emitted from the light emitting unit 20 via the optical fiber cable 50 is collimated by the collimating optical system 79, and then the laser light is horizontally converted by the horizontal scanning unit 80 and the vertical scanning unit 90. In addition, two-dimensional scanning is performed in the vertical direction, and the light is emitted toward the pupil 101a via the second relay optical system 95. An image corresponding to the image signal S is projected on the retina 101b by the laser light, and the user recognizes the image corresponding to the image signal S.

  The laser light emitted from the second relay optical system 95 is reflected by the half mirror 31 positioned in front of the eye 101, and the external light 200 passes through the half mirror 31 and enters the user's pupil 101a. Thus, the user can visually recognize an image obtained by superimposing an image based on laser light on an external scene based on external light. Further, in the second relay optical system 95, the respective laser beams are made substantially parallel to each other by the lenses 95a and converted into convergent laser beams. The laser beams are converted into substantially parallel laser beams by the lens 95b, and the center lines of these laser beams are converted so as to converge on the user's pupil 101a. The first relay optical system 85 that relays the laser beam between the horizontal scanning unit 80 and the vertical scanning unit 90 receives the laser beam scanned in the horizontal direction by the reflection mirror of the optical scanning element 81 in the horizontal scanning unit 80. It has a function of converging on the reflection mirror of the optical scanning element 91 in the vertical scanning unit 90. The lens 95b functions as an eyepiece optical system that projects the image according to the image signal S onto the user's retina 101b by causing the laser light scanned by the scanning unit 30 to enter the user's eye 101 as a projection unit. To do.

  Here, the horizontal scanning unit 80 is an optical system that horizontally scans a laser beam in the horizontal direction for each scanning line of an image to be displayed, and a resonance type optical scanning element 81 having a reflection mirror 82 such as a galvanometer mirror. (An example of the second optical scanning element), a horizontal drive signal generator 83 (an example of the second driving means) that resonates and drives the optical scanning element 81, and a swing state of the reflection mirror 82 of the optical scanning element 81 are detected. And a swing detection circuit 84 for performing the above operation. The vertical scanning unit 90 is an optical system that vertically scans a laser beam vertically from the first horizontal scanning line to the last horizontal scanning line for each frame of an image to be displayed, and is reflected by a galvanometer mirror or the like. An optical scanning element 91 having a mirror 92 (an example of an optical scanning element) and a vertical drive signal for generating a drive signal S101 for swinging the reflection mirror 92 of the optical scanning element 91 in a non-resonant state based on the vertical control signal 62 A generator 93 is provided. The optical scanning elements 81 and 91 use galvanometer mirrors here, but if the reflection mirror (deflection surface) can be oscillated or rotated so as to scan the laser light, piezoelectric driving, Any driving method such as electromagnetic driving or electrostatic driving may be used.

  In FIG. 9, the maximum scanning range W (the range formed by the horizontal scanning maximum range Xa and the vertical scanning maximum range Ya shown in FIG. 9) by the optical scanning elements 81 and 91 of the horizontal scanning unit 80 and the vertical scanning unit 90 is effective. The relationship with the scanning range Z (the range formed by the horizontal effective scanning range X1 and the vertical effective scanning range Y1 shown in FIG. 9) is shown. Here, the “maximum scanning range” means the maximum range in which the optical scanning element 81 of the horizontal scanning unit 80 and the optical scanning element 91 of the vertical scanning unit 90 can scan image light.

  The horizontal drive signal generator 83 and the vertical drive signal generator 93 drive the optical scanning elements 81 and 91 based on the horizontal control signal 61 and the vertical control signal 62 output from the signal supply circuit 18. Then, in the maximum scanning range W of the optical scanning element 81 and the optical scanning element 91, the scanning position of the optical scanning element 81 and the optical scanning element 91 is within the effective scanning range Z according to the image signal from the light emitting unit 20. Intensity-modulated image light is emitted. As a result, image light is scanned in the effective scanning range Z by the optical scanning element 81 and the optical scanning element 91, and image light for one frame is scanned in the effective scanning range Z. This scanning is repeated for each frame image. FIG. 9 virtually shows the locus γ of the image light scanned by the light scanning element 81 and the light scanning element 91 when it is assumed that the image light is always emitted from the light emitting unit 20. However, the number of scans in the horizontal scanning direction X by the optical scanning element 81 is about several hundreds or thousands per frame. In FIG. 9, the locus γ of image light is simply shown.

(Configuration and operation of vertical drive signal generator 93)
Here, the configuration and operation of the vertical drive signal generator 93, which is a characteristic part of the retinal scanning display 100, will be described in detail with reference to FIG.

  The vertical drive signal generator 93 is a drive signal for forcibly driving the reflection mirror 92 of the optical scanning element 91 in a non-resonant mode, and is a drive obtained by performing low-pass filter processing and notch filter processing on a linearly changing sawtooth waveform signal. The signal S101 is generated, and the reflection mirror 92 of the optical scanning element 91 is swung in a sawtooth shape (see FIG. 9), and is configured as follows.

  That is, as shown in FIG. 10, the vertical drive signal generator 93 includes a drive processing unit 170, a basic waveform storage unit 171, a filter unit 172, a filter characteristic adjustment unit 173, a ringing detection unit 174, and a drive waveform storage unit 175. A drive signal generation unit 176 is provided. The drive processing unit 170, the basic waveform storage unit 171, the filter unit 172, the filter characteristic adjustment unit 173, the ringing detection unit 174, the drive waveform storage unit 175, and the drive signal generation unit 176 are respectively connected to the drive processing unit 10 and the basic waveform. The same processing as that of the storage unit 11, the filter unit 12, the filter characteristic adjustment unit 13, the ringing detection unit 14, the drive waveform storage unit 15 and the drive signal generation unit 16 is performed.

  The basic waveform storage unit 171 stores in advance data of a basic waveform signal S111 obtained by performing low-pass filter processing (for example, filter processing using an 18th-order low-pass filter) on a sawtooth waveform signal that linearly changes in the same manner as the sawtooth waveform signal S10. I am letting. Data of the basic waveform signal S111 stored in the basic waveform storage unit 171 is read by the drive processing unit 170 and input to the filter unit 172. The filter unit 172 performs a notch filter process on the basic waveform signal S111 with a predetermined parameter to generate a drive waveform signal S112.

  Here, parameters used in the filter unit 172 are determined by the filter characteristic adjustment unit 173 and input to the filter unit 172. The parameter determined by the filter characteristic adjustment unit 173 is a parameter corresponding to the resonance characteristic unique to the optical scanning element 91, and can be dealt with even when there is an individual difference in the resonance frequency unique to the optical scanning element 91.

  The filter characteristic adjustment unit 173 determines the parameters of the filter unit 172 based on the ringing waveform of the optical scanning element 91 output from the ringing detection unit 174. Similar to the filter characteristic adjustment unit 13 of the optical scanning apparatus 1, the filter characteristic adjustment unit 173 can execute parameter adjustment processing. By this processing, the sharpness Q of the attenuation region and the center frequency fo in the notch filter 172a are obtained. It can be decided. The parameter adjustment process is the same as the process of the filter characteristic adjustment unit 13, and the description thereof is omitted here.

  The ringing detection unit 174 acquires a swing waveform of the reflection mirror 92 of the optical scanning element 91, extracts a ringing waveform included in the swing waveform by bandpass filter processing or the like, and stores the ringing waveform in an internal storage unit. Remember. Further, the ringing detection unit 174 detects the frequency fg of the extracted ringing waveform, and outputs information on the detected ringing frequency fg to the filter characteristic adjustment unit 173. Further, the ringing detection unit 174 compares the ringing waveform previously stored in the internal storage unit with the ringing waveform stored this time, detects the phase change of the ringing, and detects the information on the phase change of the ringing as a filter characteristic adjustment unit To 173. The swinging state of the reflection mirror 92 is detected by detecting, for example, a displacement of a beam member that drives the reflection mirror 92 with a piezoelectric element or the like, and detecting a voltage generated by the piezoelectric element with a ringing detection unit 174. It can be carried out. In addition, the electrode is attached to the bottom of the reflection mirror 92, the electrode is attached to the main body of the optical scanning element 91 facing the electrode, and the reflection mirror 92 is swung so as to detect the capacitance generated between these electrodes. The motion state may be detected.

  The drive signal generation unit 176 generates the drive signal S101 by reading out the data of the drive waveform signal S112 from the drive waveform storage unit 175 with the clock CLK0 having a predetermined frequency and performing analog conversion using the internal D / A converter. Here, the clock CLK0 is a clock signal generated by the signal supply circuit 18 and notified to the drive signal generator 176. The signal supply circuit 18 generates a clock CLK0 based on the oscillation frequency of the optical scanning element 81 detected by the oscillation detection circuit 84 and notifies the drive signal generation unit 176 of the clock CLK0. This eliminates the need to change the data of the sawtooth waveform signal S110 stored in the basic waveform storage unit 171 even when the vertical scanning frequency (frame frequency) has to be changed due to the change in the horizontal scanning frequency, thereby increasing the storage capacity. Can be suppressed.

  When the frequency of the clock CLK0 fluctuates by a predetermined value or more, the drive processing unit 170 reads the data of the basic waveform signal S111 from the basic waveform storage unit 171 with the clock CLK0, inputs the data to the filter unit 172, and outputs the data from the filter unit 172. Data of the output drive waveform signal S112 is stored in the drive waveform storage unit 175, and the drive waveform signal S112 is updated. As a result, the drive signal S101 that accurately suppresses ringing can be output from the drive signal generation unit 176.

  Thereafter, the drive signal generation unit 176 inputs the generated drive signal S101 to the optical scanning element 91 and forcibly drives the reflection mirror 92 of the optical scanning element 91 in the non-resonant mode.

  The drive processor 170 outputs a plurality of sawtooth waveform drive signals S101 by continuously repeating the process of reading the sawtooth waveform signal S110 from the basic waveform storage unit 171 and generating the drive signal S101. Thus, the laser beam emitted from the light emitting unit 20 is continuously and repeatedly scanned in the vertical direction.

  In the retinal scanning display 100, the parameter adjustment processing (similar to the processing in FIG. 7) of the filter unit 172 in the vertical drive signal generator 93 is performed based on the vertical control signal 62 from the signal supply circuit 18. Before the laser beam corresponding to the image signal S is emitted from the unit 20 and immediately after the drive of the optical scanning element 91 is started by the vertical drive signal generator 93, the parameter of the filter unit 172 is set and then the light A laser beam corresponding to the image signal S is emitted from the emission unit 20.

  Further, when the user operates the operation unit 40, the parameter setting of the filter unit 172 in the vertical drive signal generator 93 is executed based on the vertical control signal 62 from the signal supply circuit 18. Even when the laser beam corresponding to the image signal S is emitted from the light emitting unit 20, the parameter of the filter unit 172 in the vertical drive signal generator 93 is set based on the vertical control signal 62 from the signal supply circuit 18. The setting can be executed.

  Although some of the embodiments of the present invention have been described in detail with reference to the drawings, these are exemplifications, and the present invention is implemented in other forms with various modifications and improvements based on the knowledge of those skilled in the art. Is possible.

  The present invention has been described through the above-described embodiments. According to the image signal display apparatus including the drive signal generator 6 and the optical scanning device 1 including the drive signal generator 6 and the vertical drive signal generator 93 according to the present embodiment, Can be expected.

(1) Basic waveform storage units 11 and 171 for storing data of basic waveform signals S11 and S111 for generating periodic drive signals S1 and S101, and basic waveform signals S11 and S11 from the basic waveform storage units 11 and 171, respectively. The data of S111 is read out, the notch filter processing is performed on the basic waveform signals S11 and S111 to generate the drive waveform signal, and the data of the drive waveform signals S12 and S112 generated by the filter unit 12 are stored. Drive waveform storage units 15 and 175 for driving, and drive signal generation units 16 and 176 for generating the drive signals S1 and S101 by reading the data of the drive waveform signals S12 and S112 from the drive waveform storage units 15 and 175 and converting them to analog. And reflecting mirrors 5a and 9 of the optical scanning elements 5 and 91 according to the drive signals S1 and S101. Drive signal generators 6 and 93 forcibly swinging the optical scanning elements 5 and 92 in the non-resonant mode when the reflecting mirrors 5a and 92 are swung by the drive processing units 10 and 170. Ringing detection units 14 and 174 that detect the phase of ringing generated by the natural resonance, and the sharpness of the attenuation region in the notch filters 12a and 172a are adjusted according to the ringing phase detected by the ringing detection units 14 and 174. Since the filter characteristic adjustment units 13 and 173 are provided, drive signals S1 and S101 for forcibly driving the reflection mirrors 5a and 92 of the optical scanning elements 5 and 91 in the non-resonant mode are generated using the notch filters 12a and 172a. In doing so, the sharpness Q of the attenuation region in the notch filters 12a and 172a can be quickly adjusted.

(2) Further, the filter characteristic adjustment units 13 and 173 set the notch filter 12a and 172a with the center frequency fo of the attenuation region set higher than the ringing frequency detected by the ringing detection units 14 and 174. , 172a, the sharpness Q is decreased when the ringing phase is delayed, and the sharpness Q is increased when the ringing phase is advanced. The sharpness Q can be adjusted more quickly.

(3) Further, the filter characteristic adjustment units 13 and 173 set the notch filter 12a and 172a with the center frequency fo of the attenuation region set lower than the ringing frequency detected by the ringing detection units 14 and 174. , 172a, the sharpness Q is increased when the ringing phase is delayed, and the sharpness Q is decreased when the ringing phase is advanced. Can be adjusted more quickly.

(4) The ringing detection units 14 and 174 detect the ringing frequency, and the filter characteristic adjustment units 13 and 173 detect the notch filter 12a according to the ringing phase and frequency detected by the ringing detection units 14 and 174. , 172a, the sharpness Q of the attenuation region is adjusted, which is effective when the ringing frequency varies. That is, even when there is an individual difference in the resonance frequency unique to the optical scanning element 91, the sharpness Q of the attenuation region in the notch filters 12a and 172a can be adjusted with high accuracy.

(5) The filter characteristic adjusting units 13 and 173 adjust the center frequency of the notch filters 12a and 172a or the sharpness of the attenuation region while the reflecting mirrors 5a and 92 of the optical scanning elements 5 and 91 are oscillating. Therefore, the ringing waveform of the optical scanning elements 5 and 91 is continued even when the resonance frequency inherent to the optical scanning elements 5 and 91 changes due to a change in ambient temperature or continuous driving of the optical scanning elements 5 and 91. Thus, the laser beam can be suppressed within a predetermined range, and the scanning accuracy of the laser beam by the optical scanning elements 5 and 91 can be improved.

(6) The filter characteristic adjusting units 13 and 173 adjust the center frequency fo of the notch filters 12a and 172a or the sharpness Q of the attenuation region when the reflection mirrors 5a and 92 of the optical scanning elements 5 and 91 start to swing. Therefore, the scanning accuracy of the laser beam by the optical scanning elements 5 and 91 can be improved from the start of the scanning.

(7) In addition, operation units 7 and 40 for starting adjustment of the center frequency fo of the notch filters 12a and 172a or the sharpness Q of the attenuation region are provided. The filter characteristic adjustment units 13 and 173 are operated by the operation means. When this is done, the center frequency fo of the notch filters 12a and 172a or the sharpness Q of the attenuation region is adjusted, so that the power consumption can be suppressed by performing the adjustment process as necessary.

DESCRIPTION OF SYMBOLS 1 Optical scanning apparatus 2 Control part 3,20 Light emission part 4,30 Optical scanning part 5,81,91 Optical scanning element 6 Drive signal generator 7,40 Operation part 10,170 Drive processing part 11,171 Basic waveform memory | storage part 12, 172 Filter unit 12a, 172a Notch filter 13, 173 Filter characteristic adjustment unit 14, 174 Ringing detection unit 15, 175 Drive waveform storage unit 16, 176 Drive signal generation unit 93 Vertical drive signal generator 100 Retina scanning display

Claims (10)

Basic waveform storage means for storing data of a basic waveform signal for generating a periodic drive signal;
Filter means for reading out data of the basic waveform signal from the basic waveform storage means, performing notch filter processing on the basic waveform signal, and generating a drive waveform signal;
Drive waveform storage means for storing drive waveform signal data generated by the filter means;
Drive signal generation means for generating the drive signal by reading the data of the drive waveform signal from the drive waveform storage means and converting it to analog, and the reflection mirror of the optical scanning element is set in the non-resonant mode by the drive signal. A drive signal generator forcibly swinging,
Ringing detection means for detecting a phase of ringing caused by the natural resonance of the optical scanning element when the reflection mirror is swung by the drive processing means;
A drive signal generator comprising: filter characteristic adjusting means for adjusting the sharpness of the attenuation region in the notch filter in accordance with the phase of ringing detected by the ringing detecting means.   The filter characteristic adjusting unit is configured to change the sharpness of the attenuation region in the notch filter in a state in which the center frequency of the attenuation region in the notch filter is set higher than the ringing frequency detected by the ringing detection unit. 2. The drive signal generator according to claim 1, wherein the sharpness is decreased when the phase of the ringing is delayed, and the sharpness is increased when the phase of the ringing advances.   When the filter characteristic adjusting means changes the sharpness of the attenuation area in the notch filter in a state where the center frequency of the attenuation area in the notch filter is set lower than the ringing frequency detected by the ringing detection means, 3. The drive signal generator according to claim 1, wherein when the phase of the ringing is delayed, the sharpness is increased, and when the phase of the ringing is advanced, the sharpness is decreased. The ringing detection means detects the frequency of the ringing,
The said filter characteristic adjustment means adjusts the sharpness of the attenuation area in the said notch filter according to the phase and frequency of the ringing detected by the said ringing detection means. A drive signal generator according to claim 1.   The said filter characteristic adjustment means adjusts the sharpness of the attenuation | damping area in the said notch filter while rocking | reflecting the reflective mirror of the said optical scanning element, The any one of Claims 1-4 characterized by the above-mentioned. Drive signal generator.   The said filter characteristic adjustment means adjusts the sharpness of the said notch filter attenuation | damping area | region at the time of the rocking | fluctuation start of the reflective mirror of the said optical scanning element, The one of Claims 1-4 characterized by the above-mentioned. Drive signal generator. Operation means for starting adjustment of the center frequency or sharpness of the attenuation region in the notch filter;
5. The drive signal according to claim 1, wherein the filter characteristic adjustment unit adjusts the sharpness of the attenuation region in the notch filter when the operation unit is operated. 6. Generator.   8. An optical scanning device comprising: the optical scanning element according to claim 1; and the drive signal generator; and a light emitting unit that emits laser light to be scanned by the optical scanning element. A light emitting unit that emits image light having an intensity according to an image signal;
The optical scanning element and the drive signal generator according to any one of claims 1 to 7,
A second optical scanning element that scans light in a direction intersecting a scanning direction of the optical scanning element;
Second driving means for generating a second drive signal for driving the second optical scanning element,
2. An image display device, wherein the image light is displayed two-dimensionally by the optical scanning element and the second optical scanning element.   The image display apparatus according to claim 9, further comprising an eyepiece optical system that projects image light scanned by the optical scanning element and the second optical scanning element onto a retina of at least one eye of a user.

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