Signal processing circuit and control device

Abstract

This signal processing circuit is provided with: a filter that performs filtering on an input signal; and a filter coefficient changing unit that automatically changes a coefficient of the filter in accordance with the frequency of the input signal.

Description

Signal processing circuit and control device

[0001] The present invention relates to a signal processing circuit and a control device.

[0002] 2. Description of the Related Art Conventionally, a signal processing circuit is known that includes a low-pass filter that removes high-frequency noise from an input signal and a high-pass filter that removes DC components from the input signal (see, for example, Patent Document 1 below).

[0003] JP 2009-023475 A

[0004] However, in conventional signal processing circuits, when the frequency of the input signal changes, the frequency characteristics of the filter (particularly the cutoff frequency) become inappropriate, which can cause an unintended phase shift in the signal, and can prevent the filter from operating normally.

[0005] A signal processing circuit according to one embodiment includes a filter that performs filtering on an input signal, and a filter coefficient changing unit that automatically changes the coefficient of the filter in accordance with the frequency of the input signal.

[0006] According to the signal processing circuit of one embodiment, the filter can operate normally even if the frequency of the input signal changes.

[0007] FIG. 1 shows the configuration of an input device according to one embodiment. FIG. 2 shows the circuit configuration of a signal processing circuit according to one embodiment. FIG. 3 shows an example (first example) of the hardware configuration of a filter coefficient modification unit included in a signal processing circuit according to one embodiment. FIG. 4 shows an example (first example) of the calculation of filter coefficients by a calculation unit of a filter coefficient modification unit included in a signal processing circuit according to one embodiment. FIG. 1 shows an example (second example) of calculation of a filter coefficient by a calculation unit of a filter coefficient modification unit included in a signal processing circuit according to an embodiment. FIG. 2 shows an example (first example) of frequency characteristics of a filter coefficient calculated by a calculation unit of a filter coefficient modification unit included in a signal processing circuit according to an embodiment. FIG. 3 shows an example (second example) of frequency characteristics of a filter coefficient calculated by a calculation unit of a filter coefficient modification unit included in a signal processing circuit according to an embodiment. FIG. 4 shows an example (second example) of hardware configuration of a filter coefficient modification unit included in a signal processing circuit according to an embodiment. FIG. 5 shows a configuration of an input device according to another embodiment. FIG. 6 shows a configuration of a vibration generator according to another embodiment. FIG. 7 shows a configuration of a frequency measurement circuit according to another embodiment. FIG. 8 shows an example (first example) of calculation of a resonance frequency by a frequency measurement circuit according to another embodiment. FIG. 9 shows an example (second example) of calculation of a resonance frequency by a frequency measurement circuit according to another embodiment.

[0008] [One Embodiment] Hereinafter, one embodiment will be described with reference to the drawings.

[0009] 1 is a diagram showing the configuration of an input device 1 according to an embodiment. The input device 1 shown in FIG. 1 includes a touch panel 2, a base 3, a control device 100, and an electromagnetic actuator 150.

[0010] The touch panel 2 is an example of an "operation device." The touch panel 2 is a flat member having an operation surface on its surface that can be touched. The touch panel 2 has, for example, an electrostatic sensor made up of a plurality of detection electrodes, and the electrostatic sensor detects a touch operation on the operation surface by an operator's finger.

[0011] The base 3 is a flat plate-like member provided on the rear side of the touch panel 2 and supporting the touch panel 2 and the electromagnetic actuator 150 .

[0012] The control device 100 controls the vibration generating operation of the electromagnetic actuator 150 in response to a touch operation on the touch panel 2 .

[0013] The electromagnetic actuator 150 is provided between the touch panel 2 and the base 3. The electromagnetic actuator 150 generates vibrations to vibrate the touch panel 2, thereby presenting vibrations to the operator's finger.

[0014] (Configuration of the vibration generator 10) Fig. 2 is a diagram showing the configuration of the vibration generator 10 according to one embodiment. In the example shown in Fig. 2, the signal processing circuit 120 is used in a control device 100 that controls an electromagnetic actuator 150. However, the use of the signal processing circuit 120 is not limited to this.

[0015] 2, the vibration generator 10 includes a control device 100 and an electromagnetic actuator 150. The control device 100 includes a signal processing circuit 120, a drive signal generation unit 130, and a drive unit 140.

[0016] The electromagnetic actuator 150 has a movable body 151, a plate-shaped elastic portion 152, a coil 153, and a strain sensor 154. The electromagnetic actuator 150 is configured to generate vibrations when a current is supplied from the driving portion 140 to the coil 153, causing the movable body 151 supported by the plate-shaped elastic portion 152 to be displaced.

[0017] The signal processing circuit 120 receives as input a detection signal detected by a strain sensor 154 (an example of a "sensor") provided in the electromagnetic actuator 150. The strain sensor 154 detects the strain of the plate-shaped elastic portion 152 in the electromagnetic actuator 150 due to the displacement of the movable body 151, and outputs a detection signal representing the detected strain of the plate-shaped elastic portion 152.

[0018] The signal processing circuit 120 performs various filtering processes on the input detection signal. Specifically, the signal processing circuit 120 includes a low-pass filter 121, a high-pass filter 122, and a phase compensation filter 123.

[0019] The low-pass filter 121 performs a filtering process on the input detection signal to remove high-frequency noise. The high-pass filter 122 performs a filtering process on the input detection signal to remove DC components. The phase compensation filter 123 performs a filtering process on the input detection signal to adjust the phase.

[0020] Then, the signal processing circuit 120 outputs the detection signal after various filtering processes to the drive signal generating section 130 .

[0021] The signal processing circuit 120 also includes a filter coefficient changing unit 124. The filter coefficient changing unit 124 automatically changes the coefficients of each filter (in this embodiment, as an example, the low-pass filter 121 and the high-pass filter 122) in accordance with the frequency of the input signal. As a result, even if the frequency of the input signal changes, the filter coefficient changing unit 124 automatically sets appropriate coefficients in accordance with the frequency of the input signal to each filter, allowing each filter to operate normally. The frequency of the input signal is detected by a frequency detection unit (not shown) provided inside or outside the signal processing circuit 120 and input to the filter coefficient changing unit 124.

[0022] The drive signal generating unit 130 generates a main drive signal for vibrating the electromagnetic actuator 150, and supplies the main drive signal to the drive unit 140, causing the drive unit 140 to control the coil 153 of the electromagnetic actuator 150 and vibrate the electromagnetic actuator 150.

[0023] In addition, the drive signal generating unit 130 generates a secondary drive signal to shorten the damping period of the vibration of the electromagnetic actuator 150 and brake the vibration, and supplies the secondary drive signal to the drive unit 140, causing the drive unit 140 to control the coil 153 of the electromagnetic actuator 150 and brake the vibration of the electromagnetic actuator 150.

[0024] At this time, the drive signal generation unit 130 detects the peak timing, bottom timing, or zero-cross timing of the detection signal from the waveform of the detection signal input from the signal processing circuit 120. Then, the drive signal generation unit 130 supplies the auxiliary drive signal to the drive unit 140 at an appropriate timing based on the timing of the detected detection signal, thereby efficiently braking the vibration of the electromagnetic actuator 150. Note that, as a specific configuration for braking the vibration of the electromagnetic actuator 150, for example, the technology disclosed in Japanese Patent Application No. 2023-127739 can be used.

[0025] (Example (first example) of filter change processing by filter coefficient change unit 124) Figure 3 is a diagram showing an example (first example) of the hardware configuration of the filter coefficient change unit 124 provided in the signal processing circuit 120 according to one embodiment.

[0026] 3, the filter coefficient modification unit 124 includes a calculation unit 124A. The calculation unit 124A automatically calculates a modified coefficient for each of the n filters (filter 1 to filter n) included in the signal processing circuit 120 in accordance with the frequency of the input signal, and sets the calculated coefficient.

[0027] For example, the calculation unit 124A calculates the coefficient f(x) for each of the n filters (filter 1 to filter n) using the following polynomial degree function (1).

[0028] f(x) = a ｎ x ｎ +a ｎ－１ bx ｎ－１ +...+a ０　 (1)

[0029] However, a ０ ,…,a ｎdenotes a fixed constant, and x denotes the input frequency.

[0030] Note that the low-pass filter 121 and the high-pass filter 122 each have a plurality of coefficients (for example, five). Therefore, the calculation unit 124A calculates each of the plurality of coefficients included in the low-pass filter 121 and the plurality of coefficients included in the high-pass filter 122 using a polynomial degree function (1) and a fixed constant.

[0031] Therefore, the signal processing circuit 120 is pre-implemented with a suitable polynomial degree function (1) and fixed constants for each of the multiple coefficients of the low-pass filter 121 and the multiple coefficients of the high-pass filter 122.

[0032] That is, the signal processing circuit 120 according to one embodiment only needs to implement the polynomial order function (1) and fixed constants for each filter, and can therefore calculate coefficients for each of the n filters according to the frequency of the input signal with relatively few resources.

[0033] The filter coefficient changing unit 124 sets the coefficient calculated by the calculation unit 124A for each of the n filters, thereby enabling the filter coefficient changing unit 124 to set an appropriate coefficient for each of the n filters according to the frequency of the input signal.

[0034] The calculation unit 124A is realized by a digital circuit (i.e., hardware) without using a processor (i.e., software). That is, the signal processing circuit 120 according to one embodiment can automatically set suitable coefficients in the filter with relatively few resources. However, if a processor can be implemented in the signal processing circuit 120, the calculation unit 124A may be realized by the processor.

[0035] (Calculation example of filter coefficients) Fig. 4 is a diagram showing a calculation example (first example) of filter coefficients by the calculation unit 124A of the filter coefficient modification unit 124 included in the signal processing circuit 120 according to an embodiment. Fig. 5 is a diagram showing a calculation example (second example) of filter coefficients by the calculation unit 124A of the filter coefficient modification unit 124 included in the signal processing circuit 120 according to an embodiment.

[0036] FIG. 4 shows the filter coefficients calculated by the calculation unit 124A of the filter coefficient change unit 124 using a first-order polynomial degree function, in comparison with the coefficients of an ideal filter.

[0037] FIG. 5 shows the filter coefficients calculated by the calculation unit 124A of the filter coefficient change unit 124 using a second-order polynomial degree function, in comparison with the coefficients of an ideal filter.

[0038] In the graphs shown in FIGS. 4 and 5, the solid lines indicate the coefficients calculated by the calculation unit 124A for the frequencies of each input signal, and the circular plots indicate the ideal coefficients for the frequencies of each input signal.

[0039] As shown in Figures 4 and 5, in the signal processing circuit 120 according to one embodiment, the calculation unit 124A of the filter coefficient modification unit 124 calculates the filter coefficients using a first-order polynomial degree function or a second-order polynomial degree function, thereby making the filter coefficients equivalent to ideal coefficients.

[0040] The calculation unit 124A needs to calculate the multiple coefficients of the low-pass filter 121 and the multiple coefficients of the high-pass filter 122. Regarding whether to use a first-order polynomial degree function or a second-order polynomial degree function for each of these multiple coefficients, it is preferable to select the most appropriate one in advance in accordance with the characteristics of the coefficients of the filter, based on the results of simulations, etc.

[0041] The selection of the degree of the polynomial degree function for each of such multiple coefficients may be performed manually by an operator, or may be performed automatically by a processing unit (not shown) provided inside or outside the signal processing circuit 120 based on the results of a simulation, etc.

[0042] (Example of frequency characteristics of filter coefficients) Fig. 6 is a diagram showing an example (first example) of frequency characteristics of filter coefficients calculated by the calculation unit 124A of the filter coefficient modification unit 124 included in the signal processing circuit 120 according to an embodiment. Fig. 7 is a diagram showing an example (second example) of frequency characteristics of filter coefficients calculated by the calculation unit 124A of the filter coefficient modification unit 124 included in the signal processing circuit 120 according to an embodiment.

[0043] FIG. 6 shows the frequency characteristics of the coefficients of a certain low-pass filter 121 and high-pass filter 122 calculated by the calculation unit 124A of the filter coefficient changing unit 124, in comparison with the frequency characteristics of the coefficients of an ideal filter.

[0044] FIG. 7 shows the frequency characteristics of the coefficients of the other low-pass filter 121 and high-pass filter 122 calculated by the calculation unit 124A of the filter coefficient changing unit 124 in comparison with the ideal frequency characteristics.

[0045] In the graphs shown in FIGS. 6 and 7, the dotted lines indicate the frequency characteristics of the coefficients calculated by the calculation unit 124A, and the solid lines indicate ideal frequency characteristics.

[0046] As shown in Figures 6 and 7, in a signal processing circuit 120 according to one embodiment, the calculation unit 124A of the filter coefficient modification unit 124 calculates the filter coefficients using a first-order polynomial degree function or a second-order polynomial degree function, thereby making it possible to make the frequency characteristics of the filter coefficients equivalent to ideal frequency characteristics.

[0047] (Example (second example) of filter change processing by filter coefficient change unit 124) Figure 8 is a diagram showing an example (second example) of the hardware configuration of the filter coefficient change unit 124 provided in the signal processing circuit 120 according to one embodiment.

[0048] In the example shown in FIG. 8, the filter coefficient changing unit 124 includes a selecting unit 124B and a memory 124C.

[0049] The memory 124C stores a plurality of suitable coefficients for each frequency range of the input signal for each of the n filters (filter 1 to filter n) included in the signal processing circuit 120. The multiple coefficients stored in the memory 124C are determined in advance based on the results of simulations, etc., and are suitable for causing the filters to operate normally.

[0050] The selection unit 124B selects, for each of the n filters (filter 1 to filter n) included in the signal processing circuit 120, a coefficient corresponding to the frequency of the input signal from among the multiple coefficients stored in the memory 124C.

[0051] In other words, the signal processing circuit 120 according to one embodiment only needs to implement a table in which multiple coefficients are set in the memory 124C, and can therefore calculate coefficients corresponding to the frequency of the input signal for each of the n filters with relatively few resources.

[0052] The filter coefficient changing unit 124 sets the coefficient selected by the selecting unit 124B for each of the n filters, thereby enabling the filter coefficient changing unit 124 to set an appropriate coefficient for each of the n filters according to the frequency of the input signal.

[0053] Note that both the low-pass filter 121 and the high-pass filter 122 have multiple (e.g., five) coefficients. Therefore, the selection unit 124B selects each of the multiple coefficients included in the low-pass filter 121 and the multiple coefficients included in the high-pass filter 122 from the multiple coefficients stored in the memory 124C.

[0054] Therefore, in the memory 124C, a plurality of suitable coefficients for each frequency of the input signal are preset for each of the plurality of coefficients provided in the low-pass filter 121 and the plurality of coefficients provided in the high-pass filter 122.

[0055] Furthermore, the selection unit 124B is realized by a digital circuit (i.e., hardware) without using a processor (i.e., software). That is, the signal processing circuit 120 according to one embodiment can automatically set suitable coefficients in the filter with relatively few resources. However, if a processor can be implemented in the signal processing circuit 120, the selection unit 124B may be realized by the processor.

[0056] Other Embodiments Hereinafter, other embodiments will be described with reference to the drawings.

[0057] Conventionally, a technique has been disclosed in which zero crossings of a signal to be measured are detected and the frequency of the signal to be measured is measured based on the detection results (see, for example, Japanese Patent Application Laid-Open No. 2013-145146).

[0058] However, when conventional technology is used, for example, for braking control of a vibration generator, the signal to be measured suddenly stops when the vibration generator is suddenly braked, making it impossible to accurately measure the frequency of the signal to be measured, and there is a risk that the measurement value of the resonant frequency used for braking control of the vibration generator will be updated by an inappropriate measurement value.

[0059] A frequency measurement circuit according to another embodiment is a frequency measurement circuit that measures the resonant frequency of a vibration detection signal output from a sensor that detects vibrations of a vibration generating device, and includes a frequency calculation unit that calculates a measurement value of the resonant frequency, and a frequency update determination unit that determines, based on the measurement value calculated by the frequency calculation unit, whether or not to update the measurement value used for brake control of the vibration generating device with the measurement value calculated by the frequency calculation unit.

[0060] According to a frequency measurement circuit of another embodiment, it is possible to determine whether or not to update the measurement value used for brake control of the vibration generating device depending on the measurement value of the resonant frequency, thereby preventing the measurement value of the resonant frequency used for brake control of the vibration generating device from being updated with an inappropriate measurement value.

[0061] 9 is a diagram showing the configuration of an input device 1 according to another embodiment. The input device 1 shown in FIG. 9 includes a touch panel 2, a base 3, a control device 100-2, and an electromagnetic actuator 150.

[0062] The touch panel 2 is an example of an "operation device." The touch panel 2 is a flat member having an operation surface on its surface that can be touched. The touch panel 2 has, for example, an electrostatic sensor made up of a plurality of detection electrodes, and the electrostatic sensor detects a touch operation on the operation surface by an operator's finger.

[0063] The base 3 is a flat plate-like member provided on the rear side of the touch panel 2 and supporting the touch panel 2 and the electromagnetic actuator 150 .

[0064] The control device 100-2 controls the vibration generating operation of the electromagnetic actuator 150 in response to a touch operation on the touch panel 2.

[0065] The electromagnetic actuator 150 is provided between the touch panel 2 and the base 3. The electromagnetic actuator 150 generates vibrations to vibrate the touch panel 2, thereby presenting vibrations to the operator's finger.

[0066] (Equation of motion for spring damping vibration) Here, the equation of motion for spring damping vibration will be explained.

[0067] When there is viscous resistance proportional to the velocity, the following formula (1) holds: ｓｐ indicates the spring constant [N / M], and D indicates the damping constant [N / (m / s)].

[0068]

[0069] The equation of motion of an object with mass m is expressed by the following equation (2).

[0070]

[0071] Here, when the following equations (3) and (4) are used, the general solution when 0<Z<1 can be obtained by the following equation (5).

[0072]

[0073]

[0074]

[0075] In addition, w calculated by the following formula (6) and formula (7) ｄ and f ｄ is called the damped natural frequency.

[0076]

[0077]

[0078] (Configuration of the vibration generator 10) Fig. 10 is a diagram showing the configuration of the vibration generator 10 according to another embodiment. In the example shown in Fig. 10, the signal processing circuit 120 is used in a control device 100-2 that controls an electromagnetic actuator 150. However, the use of the signal processing circuit 120 is not limited to this.

[0079] 10, the vibration generator 10 includes a control device 100-2 and an electromagnetic actuator 150. The control device 100-2 has a signal processing circuit 120, a drive signal generation unit 130, a drive unit 140, and a frequency measurement circuit 160.

[0080] The electromagnetic actuator 150 has a movable body 151, a plate-shaped elastic portion 152, a coil 153, and a strain sensor 154. The electromagnetic actuator 150 is configured to generate vibrations when a current is supplied from the driving portion 140 to the coil 153, causing the movable body 151 supported by the plate-shaped elastic portion 152 to be displaced.

[0081] The signal processing circuit 120 receives as input a detection signal detected by a strain sensor 154 (an example of a "sensor") provided in the electromagnetic actuator 150. The strain sensor 154 detects the strain of the plate-shaped elastic portion 152 in the electromagnetic actuator 150 due to the displacement of the movable body 151, and outputs a detection signal representing the detected strain of the plate-shaped elastic portion 152.

[0082] The signal processing circuit 120 performs various filtering processes on the input detection signal. Specifically, the signal processing circuit 120 includes a low-pass filter 121, a high-pass filter 122, and a phase compensation filter 123.

[0083] The low-pass filter 121 performs a filtering process on the input detection signal to remove high-frequency noise. The high-pass filter 122 performs a filtering process on the input detection signal to remove DC components. The phase compensation filter 123 performs a filtering process on the input detection signal to adjust the phase.

[0084] Then, the signal processing circuit 120 outputs the detection signal after various filtering processes to the drive signal generating section 130 .

[0085] The drive signal generating unit 130 generates a main drive signal for vibrating the electromagnetic actuator 150, and supplies the main drive signal to the drive unit 140, causing the drive unit 140 to control the coil 153 of the electromagnetic actuator 150 and vibrate the electromagnetic actuator 150.

[0086] In addition, the drive signal generating unit 130 generates a secondary drive signal to shorten the damping period of the vibration of the electromagnetic actuator 150 and brake the vibration, and supplies the secondary drive signal to the drive unit 140, causing the drive unit 140 to control the coil 153 of the electromagnetic actuator 150 and brake the vibration of the electromagnetic actuator 150.

[0087] At this time, the drive signal generation unit 130 detects the peak timing, bottom timing, or zero-cross timing of the detection signal from the waveform of the detection signal input from the signal processing circuit 120. Then, the drive signal generation unit 130 supplies the auxiliary drive signal to the drive unit 140 at an appropriate timing based on the detected timing of the detection signal, thereby enabling efficient braking of the vibration of the electromagnetic actuator 150.

[0088] 10 , the control device 100-2 includes a frequency measurement circuit 160. The frequency measurement circuit 160 measures the resonance frequency of the signal input from the strain sensor 154 to the signal processing circuit 120. The frequency measurement circuit 160 then outputs the measured value of the resonance frequency to the downstream signal processing circuit 120, etc. As a result, the measured value of the resonance frequency measured by the frequency measurement circuit 160 is used for braking control of the electromagnetic actuator 150 by the control device 100-2. By using the highly accurate measured value of the resonance frequency measured by the frequency measurement circuit 160, the control device 100-2 can perform braking control of the electromagnetic actuator 150 with high precision at appropriate timing according to the actual resonance frequency of the electromagnetic actuator 150.

[0089] Specifically, when the control device 100-2 sets the algorithm to a frequency that is the same as the vibration frequency of the electromagnetic actuator 150, it can correctly output a brake signal that cancels out the vibration of the electromagnetic actuator 150, and rapidly damp the vibration of the electromagnetic actuator 150.

[0090] On the other hand, in the control device 100-2, if a frequency different from the vibration frequency of the electromagnetic actuator 150 is set in the algorithm, or if the clock frequency of the IC fluctuates and the vibration frequency of the electromagnetic actuator 150 becomes different from the frequency set in the algorithm, the brake signal that cancels out the vibration of the electromagnetic actuator 150 cannot be output correctly, and the vibration of the electromagnetic actuator 150 can be damped gently but not suddenly.

[0091] Therefore, in order to efficiently damp the vibration of the electromagnetic actuator 150 even if the vibration frequency of the electromagnetic actuator 150 differs from the frequency set in the algorithm, the control device 100-2 constantly measures the vibration frequency of the electromagnetic actuator 150 with high precision in the background using the frequency measurement circuit 160, and updates the frequency set in the algorithm to the measured vibration frequency.

[0092] As a specific configuration for braking the vibration of the electromagnetic actuator 150, for example, the technology disclosed in Japanese Patent Application No. 2023-127739 can be used.

[0093] 11 is a diagram showing the configuration of a frequency measurement circuit 160 according to another embodiment. As shown in FIG. 11, the frequency measurement circuit 160 includes a filter unit 161, a zero-cross detection unit 162, a peak-bottom detection unit 163, a selection unit 164, a calculation period determination unit 165, a frequency calculation unit 166, and a frequency update determination unit 167.

[0094] The filter unit 161 performs a filtering process to remove specific frequency components from the input signal. Specifically, the filter unit 161 includes a low-pass filter 161A that removes high-frequency noise from the input signal, and a high-pass filter 161B that removes DC components from the input signal.

[0095] The zero-cross detector 162 detects zero-cross points from the signal that has been filtered by the filter 161 .

[0096] The peak / bottom detector 163 detects peak points and bottom points from the signal that has been filtered by the filter 161 .

[0097] The selection unit 164 selects the zero cross points detected by the zero cross detection unit 162 or the peak points and bottom points detected by the peak bottom detection unit 163 as parameters used by the frequency calculation unit 166 to calculate the resonant frequency.

[0098] The calculation period determination unit 165 determines a calculation period for the measurement value of the resonant frequency of the input signal based on the signal filtered by the filter unit 161 and the peak points and bottom points detected by the peak / bottom detection unit 163. In particular, the calculation period determination unit 165 determines the calculation period for the measurement value of the resonant frequency of the input signal based on the time it takes for the input signal to stop. For example, the calculation period determination unit 165 determines a relatively long calculation period when the input signal stops gradually, and determines a relatively short calculation period when the input signal stops suddenly.

[0099] The frequency calculation unit 166 calculates the measurement value of the resonant frequency of the input signal based on the parameters (zero crossing points or peak points and bottom points) selected by the selection unit 164 and the calculation period determined by the calculation period determination unit 165. For example, the frequency calculation unit 166 calculates the measurement value freq of the resonant frequency of the input signal using the following equation (8), where t1, t2, ..., tn indicate the times of cycles 1, 2, ..., n, and N indicates the number of cycles.

[0100]

[0101] The frequency update determination unit 167 determines, based on the measurement value calculated by the frequency calculation unit 166, whether or not to update the measurement value used for brake control of the vibration generating device 10 with the measurement value calculated by the frequency calculation unit 166.

[0102] For example, if the measurement value calculated by the frequency calculation unit 166 is outside a predetermined frequency range, the frequency update determination unit 167 determines that the efficiency of the brake control is sufficient, so that the measurement time for the frequency of the input signal is insufficient and the frequency of the input signal is outside the predetermined frequency range, and determines that ``the braking force due to the brake control of the vibration generating device 10 is sufficient,'' determines that the measurement value used for the brake control of the vibration generating device 10 will not be updated, and does not output the measurement value calculated by the frequency calculation unit 166 to the downstream signal processing circuit 120.

[0103] Conversely, if the measurement value calculated by the frequency calculation unit 166 is within a predetermined frequency range, the frequency update determination unit 167 determines that the efficiency of the brake control is insufficient, that the measurement time for the frequency of the input signal is sufficient, and that the frequency of the input signal is within the predetermined frequency range, and determines that ``the braking force due to the brake control of the vibration generator 10 is insufficient,'' and determines that the measurement value used for the brake control of the vibration generator 10 should be updated, and outputs the measurement value calculated by the frequency calculation unit 166 to the downstream signal processing circuit 120.

[0104] The predetermined frequency range is a suitable value determined in advance by simulation or the like so that the above determination can be made with high accuracy.

[0105] (Calculation Example (First Example) of Resonant Frequency) FIG. 12 is a diagram showing a calculation example (first example) of a resonant frequency by a frequency measurement circuit 160 according to another embodiment.

[0106] FIG. 12 shows an example in which the frequency calculation unit 166 calculates the measured value of the resonant frequency of the input signal from the peak points and bottom points of the input signal, and the frequency update determination unit 167 updates the measured value used for brake control of the vibration generator 10.

[0107] Fig. 12(a) shows the waveform of the signal after filtering by the filter unit 161. Fig. 12(b) shows the peak points and bottom points detected by the peak / bottom detection unit 163. Fig. 12(c) shows the calculation period determined by the calculation period determination unit 165. Fig. 12(d) shows the measured value of the resonant frequency calculated by the frequency calculation unit 166.

[0108] In the example shown in Fig. 12(a), the input signal gradually stops due to the absence of brake control of the vibration exciter 10 or the insufficient efficiency of the brake control of the vibration exciter 10. For this reason, as shown in Fig. 12(c), the calculation period determiner 165 determines a relatively long calculation period until the input signal stops, based on the peak points and bottom points of the input signal shown in Fig. 12(b). Then, as shown in Fig. 12(d), the frequency calculator 166 calculates the measured value of the resonant frequency of the input signal using the calculation period shown in Fig. 12(c) as the calculation target.

[0109] 12(d), the measured value of the resonant frequency calculated by the frequency calculation unit 166 is within a predetermined frequency range (i.e., below the upper limit and above the lower limit). This is because the input signal stops gradually, the number of cycles N of the input signal is sufficient, and the resonant frequency of the input signal can be measured with high accuracy.

[0110] In this case, the frequency update determination unit 167 determines that "there is no brake control or the efficiency of the brake control is insufficient" and outputs the measurement value calculated by the frequency calculation unit 166 to the signal processing circuit 120, thereby updating the measurement value used for the brake control of the vibration generator 10. Therefore, the frequency measurement circuit 160 according to another embodiment can update the measurement value of the resonant frequency used for the brake control of the vibration generator 10 with a highly accurate measurement value.

[0111] (Second Example of Calculation of Resonant Frequency) FIG. 13 is a diagram showing a second example of calculation of a resonant frequency by a frequency measurement circuit 160 according to another embodiment.

[0112] FIG. 13 shows an example in which the frequency calculation unit 166 calculates the measured value of the resonant frequency of the input signal from the peak points and bottom points of the input signal, and the frequency update determination unit 167 does not update the measured value used for brake control of the vibration generator 10.

[0113] Fig. 13(a) shows the waveform of the signal after filtering by the filter unit 161. Fig. 13(b) shows the peak points and bottom points detected by the peak / bottom detection unit 163. Fig. 13(c) shows the calculation period determined by the calculation period determination unit 165. Fig. 13(d) shows the measured value of the resonant frequency calculated by the frequency calculation unit 166.

[0114] In the example shown in Fig. 13(a), the input signal suddenly stops in response to sudden braking of the vibration generator 10. For this reason, as shown in Fig. 13(c), the calculation period determination unit 165 determines a relatively short calculation period until the input signal stops, based on the peak points and bottom points shown in Fig. 13(b). Then, as shown in Fig. 13(d), the frequency calculation unit 166 calculates the measured value of the resonant frequency of the input signal using the calculation period shown in Fig. 13(c) as the calculation target.

[0115] 13(d), the measured value of the resonant frequency calculated by the frequency calculation unit 166 is outside the predetermined frequency range (i.e., below the lower limit). This is because the input signal stops suddenly, and the number of cycles N of the input signal is insufficient. In addition, when the input signal stops suddenly, this is equivalent to an increase in the damping coefficient D, and from equation (4), Z becomes a large value, and the frequency calculated from equations (6) and (7) becomes relatively small.

[0116] In this case, the frequency update determination unit 167 determines that "the brake efficiency is sufficient" and does not output the measurement value calculated by the frequency calculation unit 166 to the signal processing circuit 120, thereby not updating the measurement value used for brake control of the vibration generator 10. Therefore, the frequency measurement circuit 160 according to another embodiment can prevent the measurement value of the resonant frequency used for brake control of the vibration generator 10 from being updated with an inappropriate measurement value.

[0117] The frequency calculation unit 166 is not limited to calculating the measurement value of the resonant frequency of the input signal from the peak points and bottom points of the input signal detected by the peak bottom detection unit 163, but may also calculate the measurement value of the resonant frequency of the input signal from the zero cross points of the input signal detected by the zero cross detection unit 162.

[0118] As described above, the frequency measurement circuit 160 according to another embodiment is a frequency measurement circuit 160 that measures the resonant frequency of a vibration detection signal output from a sensor that detects vibrations of the vibration generating device 10, and includes a frequency calculation unit 166 that calculates a measurement value of the resonant frequency, and a frequency update determination unit 167 that determines, based on the measurement value calculated by the frequency calculation unit 166, whether or not to update the measurement value used for brake control of the vibration generating device 10 with the measurement value calculated by the frequency calculation unit 166.

[0119] As a result, the frequency measurement circuit 160 of another embodiment can determine whether or not to update the measurement value used for brake control of the vibration generating device 10 depending on the measurement value of the resonant frequency, thereby preventing the measurement value of the resonant frequency used for brake control of the vibration generating device 10 from being updated with an inappropriate measurement value.

[0120] In addition, in a frequency measurement circuit 160 according to another embodiment, if the measurement value calculated by the frequency calculation unit 166 is outside a predetermined frequency range, the frequency update determination unit 167 determines not to update the measurement value used for brake control of the vibration generating device 10, and if the measurement value calculated by the frequency calculation unit 166 is within a predetermined frequency range, it determines to update the measurement value used for brake control of the vibration generating device 10.

[0121] As a result, the frequency measurement circuit 160 according to the other embodiment can determine whether or not to update the measurement value used for brake control of the vibration generator 10 with a relatively simple configuration.

[0122] Furthermore, a frequency measurement circuit 160 according to another embodiment includes a calculation period determination unit 165 that determines the calculation period for the measurement value of the input signal in accordance with the time it takes for the input signal to stop, and the frequency calculation unit 166 calculates the measurement value using the calculation period determined by the calculation period determination unit 165 as the calculation target.

[0123] This allows the frequency measurement circuit 160 according to the other embodiment to calculate the measurement value in an appropriate calculation period according to the time it takes for the input signal to stop.

[0124] Furthermore, a frequency measurement circuit 160 according to another embodiment includes a zero-cross detection unit 162 that detects zero-cross points in the detection signal, a calculation period determination unit 165 that determines a calculation period according to the time it takes for the detection signal to stop based on the zero-cross points detected by the zero-cross detection unit 162, and a frequency calculation unit 166 that calculates a measurement value based on the zero-cross points detected by the zero-cross detection unit 162 during the calculation period determined by the calculation period determination unit 165.

[0125] As a result, the frequency measurement circuit 160 according to the other embodiment can appropriately determine the calculation period for the measurement value based on the zero crossing points in the detection signal, and can calculate the measurement value with high accuracy.

[0126] Furthermore, a frequency measurement circuit 160 according to another embodiment includes a peak-bottom detection unit 163 that detects peak points and bottom points in the detection signal, a calculation period determination unit 165 that determines a calculation period according to the time required for the detection signal to stop based on the peak points and bottom points detected by the peak-bottom detection unit 163, and a frequency calculation unit 166 that calculates a measurement value based on the peak points and bottom points detected by the peak-bottom detection unit 163 during the calculation period determined by the calculation period determination unit 165.

[0127] As a result, the frequency measurement circuit 160 according to the other embodiment can appropriately determine the calculation period for the measurement value based on the peak points and bottom points in the detection signal, and can calculate the measurement value with high accuracy.

[0128] Comparative Example Hereinafter, with reference to FIGS. 14 to 17, a comparative example of the waveform of the drive signal and the braking effect of the electromagnetic actuator using a conventional control device and a control device 100-2 according to another embodiment will be described.

[0129] The control device 100 used in this comparative example has both the function of the control device 100 according to one embodiment (i.e., the function of automatically changing the filter coefficient according to the frequency of the input signal) and the function of the control device 100-2 according to another embodiment (i.e., the function of measuring the resonant frequency with high accuracy).

[0130] (Example of Main Drive Signal and Auxiliary Drive Signal) FIG. 14 is a diagram showing a comparative example of a main drive signal and an auxiliary drive signal output from a control device.

[0131] As shown in FIG. 14, both the conventional control device and the control device 100 according to the embodiment output a main drive signal for vibrating the electromagnetic actuator, and then output a sub-drive signal for braking the vibration of the electromagnetic actuator.

[0132] FIG. 15 is a diagram showing a comparative example of an auxiliary drive signal output from a control device. FIG. 15 is an enlarged view of the auxiliary drive signal shown in FIG. 14. FIG. 15 also illustrates an example of an auxiliary drive signal for an electromagnetic actuator when the vibration frequency of the electromagnetic actuator is shifted 5% lower. As shown in FIG. 15, the waveform of the auxiliary drive signal (dotted line in the figure) output from the control device 100 according to the embodiment to the electromagnetic actuator when the vibration frequency of the electromagnetic actuator is shifted 5% lower is shifted on the time axis and has a changed time width compared to the waveform of the auxiliary drive signal (solid line in the figure) output from a conventional control device.

[0133] This is because when the vibration frequency of the electromagnetic actuator deviates 5% lower, the secondary drive signal output from the control device 100 measures the resonant frequency with high precision, as described in the other embodiments above, and also automatically changes the filter coefficient according to the frequency of the input signal, as described in the one embodiment above.

[0134] Fig. 16 is a diagram showing the vibration waveform of the electromagnetic actuator when the vibration of the electromagnetic actuator is braked by the auxiliary drive signal output from a conventional control device. Fig. 16 illustrates the vibration waveform of the electromagnetic actuator when the vibration frequency of the electromagnetic actuator is deviated 5% lower. In Fig. 16, the solid line shows the vibration waveform of the electromagnetic actuator 150 when an appropriate brake is applied to an electromagnetic actuator 150 with no vibration frequency deviation, and the dotted line shows the vibration waveform of the electromagnetic actuator when the vibration of the electromagnetic actuator 150 with a vibration frequency deviated 5% lower is braked by the auxiliary drive signal output from a conventional control device.

[0135] Conventional control devices do not measure the resonance frequency with high precision, and therefore do not adjust the filter coefficient appropriately. As a result, when the vibration frequency of the electromagnetic actuator deviates 5% lower as shown in Figure 16, if the vibration of the electromagnetic actuator is braked by the auxiliary drive signal (see the solid line in Figure 15) output from the conventional control device, the brake cannot be applied to the electromagnetic actuator at the appropriate timing and for the appropriate duration, and the residual vibration of the electromagnetic actuator cannot be converged in a short time.

[0136] 17 is a diagram showing the vibration waveform of the electromagnetic actuator 150 when the vibration of the electromagnetic actuator 150 is braked by the auxiliary drive signal output from the control device 100 according to this embodiment. Fig. 17 illustrates the vibration waveform of the electromagnetic actuator 150 when the vibration frequency of the electromagnetic actuator 150 is deviated downward by 5%. In Fig. 17, the solid line indicates the vibration waveform of the electromagnetic actuator 150 when an appropriate brake is applied to an electromagnetic actuator 150 with no vibration frequency deviation, and the dotted line indicates the vibration waveform of the electromagnetic actuator 150 when the vibration of the electromagnetic actuator 150 with a vibration frequency deviated downward by 5% is braked by the auxiliary drive signal output from the control device 100 according to this embodiment.

[0137] The control device 100 according to the embodiment can measure the resonance frequency with high accuracy and adjust the filter coefficient appropriately. Therefore, as shown in Fig. 17 , if the vibration frequency of the electromagnetic actuator 150 deviates 5% lower, and the vibration of the electromagnetic actuator 150 is braked by the auxiliary drive signal (see the dotted line in Fig. 15 ) output from the control device 100 according to the embodiment, the brake can be applied to the electromagnetic actuator 150 at an appropriate timing and for an appropriate duration, and the residual vibration of the electromagnetic actuator 150 can be converged in a short time.

[0138] As described above, the control device 100 according to the embodiment measures the resonance frequency with high accuracy and automatically changes the filter coefficient according to the frequency of the input signal, so that the waveform of the secondary drive signal applied to the electromagnetic actuator 150 can be appropriately adjusted, thereby enhancing the braking effect of the electromagnetic actuator 150.

[0139] Therefore, for example, if the waveform of the auxiliary drive signal output from a certain control device is adjusted to be the same as the waveform of the auxiliary drive signal output from the control device 100 of the embodiment shown in Figure 15, or if the auxiliary drive signal output from a certain control device causes the residual vibration of the electromagnetic actuator to converge in a short period of time, as shown in Figure 17, it can be easily estimated that the control device is performing processing similar to that of the control device 100 of one embodiment (i.e., processing to automatically change the filter coefficient according to the frequency of the input signal) and processing similar to that of the control device 100-2 of another embodiment (i.e., processing to measure the resonant frequency with high precision).

[0140] Furthermore, according to the control device 100 of the embodiment, the electromagnetic actuator 150 can always be braked at a timing based on a predetermined timing (bottom timing, top timing, or cross timing) of the input signal, regardless of the frequency of the input signal.

[0141] Therefore, for example, even if the secondary drive signal output from a certain control device is capable of braking the electromagnetic actuator 150 at a timing based on a predetermined timing (bottom timing, top timing, or cross timing) of the input signal, regardless of the frequency of the input signal (detection signal of the strain sensor 154), it can be easily estimated that the control device performs processing similar to that of the control device 100 of one embodiment (i.e., processing to automatically change the filter coefficient according to the frequency of the input signal) and processing similar to that of the control device 100-2 of another embodiment (i.e., processing to measure the resonant frequency with high precision).

[0142] Furthermore, according to the control device 100 of the embodiment, the resonant frequency of the input signal can be measured with high accuracy, and therefore the pulse width of one period of the auxiliary drive signal for applying the brake to the electromagnetic actuator 150 can be adjusted appropriately depending on the resonant frequency of the input signal.

[0143] Therefore, for example, if the auxiliary drive signal output from a certain control device has a pulse width per period adjusted according to the resonant frequency of the input signal, it can be easily estimated that the control device is performing the same processing as the control device 100-2 of another embodiment (i.e., high-precision resonant frequency measurement processing).

[0144] Although one embodiment of the present invention has been described in detail above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

[0145] This international application claims priority based on Japanese Patent Applications Nos. 2024-024558 and 2024-024559, filed on February 21, 2024, the entire contents of which are incorporated herein by reference.

[0146] 10 Vibration generator 100, 100-2 Control device 120 Signal processing circuit 121 Low-pass filter 122 High-pass filter 123 Phase compensation filter 124 Filter coefficient change unit 124A Calculation unit 124B Selection unit 124C Memory 130 Drive signal generation unit 140 Drive unit 150 Electromagnetic actuator 151 Movable body 152 Plate-shaped elastic part 153 Coil 154 Strain sensor (sensor) 160 Frequency measurement circuit 161 Filter unit 161A Low-pass filter 161B High-pass filter 162 Zero-cross detection unit 163 Peak-bottom detection unit 164 Selection unit 165 Calculation period determination unit 166 Frequency calculation unit 167 Frequency update determination unit

Claims

1. A signal processing circuit comprising: a filter that performs filtering on an input signal; and a filter coefficient change unit that automatically changes the coefficient of the filter according to the frequency of the input signal.

2. The signal processing circuit according to claim 1, wherein the filter coefficient change unit has a calculation unit that calculates the changed coefficients using a polynomial degree function.

3. The signal processing circuit according to claim 2, characterized in that the calculation unit calculates the modified coefficients using a first-order polynomial degree function.

4. The signal processing circuit according to claim 2, characterized in that the calculation unit calculates the modified coefficients using a second-order polynomial degree function.

5. The signal processing circuit according to claim 1, characterized in that the filter coefficient change unit has a selection unit that selects, from a plurality of coefficients stored in a memory, the coefficient that corresponds to the frequency of the input signal as the coefficient after change.

6. The signal processing circuit according to any one of claims 1 to 5, characterized in that it comprises a plurality of the filters, and the filter coefficient changing unit changes the coefficients of each of the plurality of filters collectively.

7. A control device that controls an actuator that applies vibration to an operating device based on the operation of the operating device, comprising the signal processing circuit according to claim 1, wherein the input signal is a signal acquired by a sensor in response to the vibration of the actuator.

8. The control device described in claim 7, characterized in that the signal processing circuit further comprises a drive signal generation unit that generates a drive signal for braking vibration of the actuator based on the input signal after the filtering process by the filter, and the drive signal generation unit automatically changes the coefficient of the filter according to the frequency of the input signal, thereby generating the drive signal that can always brake vibration of the actuator at a predetermined timing regardless of the frequency of the input signal.

9. The control device according to claim 8, wherein the predetermined timing is a timing based on a peak timing, a bottom timing, or a zero-cross timing of the input signal.

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