JP5283069B2 - Drive control device for resonant optical deflection element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive resonance type light deflecting device that controls a turning state with high accuracy, and achieves wide-angle drive. <P>SOLUTION: The resonance type light deflecting device includes: a turning state signal input end of a resonance type light deflecting element; a comparator 3 for outputting a drive signal to the resonance type light deflecting element; a means for supplying a reference voltage to one input terminal of the comparator; a frequency controller for controlling a resonance frequency of the resonance type light deflecting element, based on a turning state signal; a clock signal generating means for generating a clock signal with a frequency controlled by the frequency controller, to be supplied to the other side input terminal of the comparator; a first amplitude controller for generating a digital signal of which the amplitude input into the turning state signal input end is controlled; and a first electric power source voltage supply means for supplying the generated digital signal to one electric power source voltage input terminal of the comparator, and for supplying the digital signal generated by the first amplitude controller, to the other electric power source voltage input terminal of the comparator, via a second D/A converter. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a drive control device for a resonant optical deflection element, and more particularly to a technique for controlling the rotational state of the resonant optical deflection element with high accuracy.

  Small-sized resonant optical deflection elements manufactured by MEMS (Micro Electro Mechanical Systems) technology can realize miniaturization and cost reduction of the optical deflection system, and various proposals have been made, and prototypes and practical applications are progressing. . There are various types of devices such as an electrostatic drive method, an electromagnetic drive method, a piezoelectric drive method, and other methods as the operation principle. For example, various electromagnetically driven light deflection elements (also referred to as galvanometer mirrors) that operate on the principle of galvanometers (movable coil electromagnetic drive) have been proposed. These electromagnetically driven light deflection elements have an optical scanning angle of plus or minus 15 degrees or more. Can be realized with a low-voltage operation using an AC voltage signal having an amplitude of about 20 Vp-p or less, and is expected to be put into practical use in a compact laser projection system (Patent Documents 1 and 2). These electromagnetically driven light deflecting elements may be used as a double-supported beam structure in which the movable part is pivotally supported by a pair of torsion bars 40 and 41 as shown in FIG.

  In this type of resonance-type electromagnetically driven light deflecting element, a plate-like movable portion 39 is pivotally supported by a pair of torsion bars 40 and 41 so as to be rotatable with respect to the support portion 42. The movable portion 39 is provided with a light beam reflecting means 43 such as a plane mirror and a drive coil 44 that is a means for forming a magnetic field by energization. The drive coil 44 circulates around the periphery of the movable portion 39. Both ends of the drive coil 44 are electrically connected to electrode take-out portions 46 and 47 provided on the support portion 42 via electric conduction means 45 such as wiring passing through the torsion bars 40 and 41. Further, magnetic field generating means 48 and 49 such as a pair of permanent magnets for applying a static magnetic field to the drive coil 44 are provided outside the movable portion 39. An alternating voltage or alternating current drive signal is applied to the electrode lead-out portions 46 and 47.

  A pair of opposite side portions of the drive coil 44 parallel to one rotation axis passing through the torsion bars 40 and 41 are caused by the interaction between the current flowing therethrough and the magnetic field components supplied from the magnetic field generating means 48 and 49. The Lorentz force is received in a direction substantially perpendicular to the surface of the movable portion 39 on which the light beam reflecting means 43 is provided (see FIG. 7). Further, since the directions of the currents flowing through the pair of opposite side portions are opposite to each other, the movable portion 39 corresponds to the magnitude of the current flowing through the drive coil 44, in other words, according to the magnitude of the drive voltage supplied to the drive coil 44. To rotate around the rotation axis.

  As a result, the light beam reflected by the light beam reflecting means 43 provided on the rotating movable portion 39 is scanned one-dimensionally. The movable portion 39 has a specific resonance frequency determined by the size, shape, and weight of the movable portion 39 and the size, shape, and material of the torsion bars 40, 41, and the drive signal of the alternating voltage or alternating current is used. When the frequency and the resonance frequency of the movable portion 39 coincide with each other, the scanning angle of the resonance-type electromagnetically driven light deflection element is maximized. By making the drive signal supplied to the drive coil 44 an AC signal corresponding to a predetermined resonance frequency, the resonant electromagnetic drive light deflection element can realize wide-angle beam scanning with a low voltage and a low current.

  In addition to the resonance-type electromagnetic drive light deflection element, various proposals have been made for resonance-type piezoelectric drive light deflection elements (Patent Documents 3 and 4). In the piezoelectric drive light deflection element, like the electromagnetic drive light deflection element, a flat plate-like movable portion is pivotally supported with respect to a support portion by a pair of torsion bars, and the movable portion has a plane mirror. A light beam reflecting means such as is provided. In the electromagnetically driven light deflection element, the movable part 39 is driven by utilizing the Lorentz force, whereas in the piezoelectrically driven light deflection element, the movable part 39 is movable by supplying vibration energy generated by the piezoelectric element to the movable part. The part is driven. The movable portion has a specific resonance frequency determined by the size, shape, and weight of the movable portion, and the size, shape, and material of the torsion bar. The frequency of the AC drive signal supplied to the piezoelectric element and the movable portion When the resonance frequency matches, the scanning angle of the resonance-type piezoelectric drive light deflection element becomes maximum. By making the drive signal supplied to the piezoelectric element an AC signal corresponding to a predetermined resonance frequency, the resonance-type piezoelectric drive light deflection element can realize wide-angle beam scanning with low power consumption.

A sine wave or a rectangular wave is widely used as the drive signal waveform supplied to the drive coil and piezoelectric element for driving the resonant optical deflection element. Since the resonant optical deflection element itself has a mechanical frequency filter characteristic, when driven near the resonant frequency, the response of the resonant optical deflection element is almost sinusoidal even if the drive waveform is a rectangular wave. . The rectangular-wave drive signal can maximize the energy that can be supplied within a certain time.
JP 2000-035549 A JP-A-10-123449 Patent Publication 2007-522528 JP 2007-94146 A

  In recent years, a high-accuracy rotation state control (scanning state control) has been strongly demanded for a drive device for a resonant optical deflection element for application to a laser projection system or a high-precision sensing system. In order to realize higher-precision control, it is desirable to detect a rotation state such as a scanning amplitude and a scanning speed of the optical deflection element and perform feedback control of the rotation state.

  The resonance frequency of a resonant optical deflecting element usually fluctuates depending on temperature or aging. If a drive signal having a preset resonance frequency is continuously supplied to the drive coil, the optical deflection is performed according to temperature changes and time passage. This is because the rotation state such as the scanning amplitude and the scanning speed of the element is not controlled constantly.

  As a means for detecting the rotation state of the optical deflection element and performing feedback control, for example, in Japanese Patent Application Laid-Open No. 2003-177347, a counter electromotive force generated in a drive coil is detected, and based on the waveform of the detected counter electromotive force. A method has been proposed in which the sine excitation current is stopped for a predetermined time, the resonance frequency is detected within the stop period, and then the movable part is driven by the sine excitation current having the detected resonance frequency. However, in the control method disclosed in Japanese Patent Application Laid-Open No. 2003-177347, the scanning amplitude can be controlled to a constant value as a result of following the resonance frequency of the resonant optical deflection element that fluctuates depending on the temperature and time. Further, it varies with time, and for example, when used in a laser projection system, the projection image varies with temperature and age. In particular, if the scanning speed becomes slower than the limit value, consistency with the video signal cannot be obtained and drawing becomes impossible.

  As a means for detecting the rotation state of the optical deflection element and performing feedback control, for example, in Japanese Patent Application Laid-Open No. 2003-66360, the resonance of the movable part is performed with a periodic waveform in which the current value is zero for a certain period within one period. A current signal having a frequency substantially equal to the frequency is supplied to the drive coil, and the rotation state of the movable part is detected based on the voltage at both ends of the drive coil during the period corresponding to the period when the current value is zero, and is driven. A method for controlling the resonance frequency and amplitude of a current signal supplied to a coil has been proposed. However, according to the method disclosed in Japanese Patent Laid-Open No. 2003-66360, the resonance frequency of the current signal supplied to the drive coil is made to follow the resonance frequency of the optical deflection element that fluctuates with temperature and with age. As described above, for example, when used in a laser projection system, the projection image fluctuates depending on temperature and aging.

  The frequency fluctuation of the current signal supplied to the drive coil is suppressed within the allowable range of fluctuation of the projection image, and the rotation state such as the scanning amplitude and scanning speed of the optical deflection element is mainly controlled by the amplitude control of the current signal. There is a need to.

  However, in the method disclosed in Japanese Patent Laid-Open No. 2003-66360, when the rotation state of the optical deflection element is controlled by controlling the amplitude of the current signal, the scanning angle and control accuracy of the optical deflection element are greatly limited. A mechanism for limiting the scanning angle will be described with reference to FIGS. FIG. 7 is an AA cross-sectional structure diagram of the general resonance type optical deflection element shown in FIG. 6. In the drive coil 44a portion, a coil current flows toward the front side in the direction perpendicular to the paper surface. In the drive coil 44b portion, FIG. A coil current flows toward the back side in the direction perpendicular to the paper surface. The magnetic field generators 48 and 49 give a static magnetic field in the direction from the left to the right of the page. At this time, since the drive coil 44a receives the Lorentz force 50 in the upward direction of the optical deflection element and the 44b portion receives the Lorentz force 51 in the downward direction, the drive coil 44a corresponds to the magnitude of the current signal (voltage signal) supplied to the drive coil 44. To rotate counterclockwise around the rotation axis.

  FIG. 8 is an AA cross-sectional structure diagram of the general resonance type optical deflection element shown in FIG. 6. In the drive coil 44a portion, a coil current flows toward the back side in the direction perpendicular to the paper surface, and in the drive coil 44b portion, FIG. A coil current flows toward the front side in the direction perpendicular to the paper surface. The magnetic field generators 48 and 49 give a static magnetic field in the direction from the left to the right of the page. At this time, the drive coil 44a receives the Lorentz force 52 in the downward direction and the 44b portion receives the Lorentz force 53 in the upward direction, so that the magnitude of the current signal (voltage signal) supplied to the drive coil 44 is increased. Accordingly, it rotates in the clockwise direction around the rotation axis.

  In this way, the optical deflection element can be rotated in both the clockwise direction and the counterclockwise direction by applying a positive and negative current signal (voltage signal) with an alternating current. FIG. 9 is a schematic diagram showing the relationship between the voltage supplied to the drive coil of the resonance type electromagnetically driven light deflection element and the scanning angle. As shown in FIG. 9, as the scanning angle increases, the distance from the magnetic field generating means to the drive coil increases, and the Lorentz force decreases, and the direction in which the Lorentz force acts and the rotation of the movable part are also reduced. The scanning angle tends to saturate because the moving direction is deviated, and the linear characteristic is not exhibited in the wide-angle scanning region. That is, it is clear that driving the resonant optical deflection element with positive and negative AC signals is effective in driving the wide angle with high efficiency and high accuracy. On the other hand, since the method according to Japanese Patent Laid-Open No. 2003-66360 can only apply a drive signal formed only with a positive bias or only with a negative bias, compared with a case where a drive signal formed with a positive and negative bias is used. The scanning angle is limited to about half. Limiting the scanning angle becomes a problem because, for example, the laser projection system limits the angle of view. Further, as described above, since the scanning angle tends to saturate in the wide-angle scanning region, it becomes difficult to drive the light deflection element that is controlled efficiently and with high precision when performing wide-angle scanning.

  As a means for detecting the rotation state of the optical deflection element and performing feedback control, for example, in Japanese Patent Laid-Open No. 2001-305471, a rectangular wave current signal formed by combining a constant current driver and a switching mechanism is used for a certain period within one period. In the meantime, a current signal having a frequency that is substantially equal to the resonance frequency of the movable part with a periodic waveform having a current value of zero is supplied to the drive coil, and the drive coil during the period corresponding to the period in which the current value is zero. A method has been proposed in which the rotational state of the movable part is detected based on the induced electromotive voltage (inductive electromotive current) generated at both ends, and the amplitude of the current signal supplied to the drive coil is controlled. The method according to Japanese Patent Laid-Open No. 2001-3015471 is similar to the method according to Japanese Patent Laid-Open No. 2003-66360, and only a drive signal formed only with a positive bias or only a negative bias can be applied. The scanning angle is limited to about half as compared with the case of using a driving signal, and it becomes difficult to drive an optical deflection element that is controlled efficiently and with high precision when performing wide-angle scanning.

  As a means for detecting the rotation state of the optical deflection element, for example, in Japanese Patent Laid-Open No. 7-218857, mutual induction between a drive coil provided in a movable part and a detection coil provided in a fixed part is used. There has been proposed a method of detecting the rotation state of the movable portion and feeding back the obtained rotation state detection signal to the drive system of the optical deflection element to control the drive current. However, in the control method according to Japanese Patent Laid-Open No. 7-218857, the drive coil and the detection coil cannot be brought close to each other in order to secure the rotation region of the movable part, and the mutual induction of the drive coil and the detection coil is performed. There is a problem that the detection level of electromotive force becomes weak and cannot be detected with high accuracy. Further, there is no specific technique for performing feedback control using the rotation state information extracted by the method for detecting the rotation state.

  As a means for detecting the rotation state of the optical deflection element, for example, in Japanese Patent Application Laid-Open No. 11-242180, a movable coil is provided with a drive coil and a detection coil, and the detection coil is generated by moving in a magnetic field. A method of detecting the rotation state of the optical deflection element using the induced electromotive force, feeding back the obtained rotation state detection signal to the drive system of the optical deflection element and controlling the drive signal, and distorting the torsion bar section A method has been proposed in which a gauge is provided, the rotation state is monitored by detecting the amount of strain, and the obtained rotation state detection signal is fed back to the drive system of the optical deflection element to control the drive signal. However, in the control method disclosed in Japanese Patent Application Laid-Open No. 11-242180, the mutual induction component of the drive coil and the detection coil is mixed as a noise component in the output signal of the detection coil, so that the output signal of the detection coil is distorted. Therefore, there is a problem that it cannot be detected with high accuracy. Further, even in the method having a strain gauge, the frequency and amplitude of the drive signal can be obtained by using the output of the self-excited oscillation circuit formed using the rotation state information extracted by the method of detecting the rotation state as the drive signal. However, there is no specific method for stably controlling the scanning angle that fluctuates when the resonance frequency of the light deflection element fluctuates depending on temperature and aging.

  As described above, as a means for detecting the rotation state such as the scanning speed and the scanning angle, a method of using the induced electromotive force generated in the drive coil, a method of adding a detection coil, and a strain amount by applying a strain gauge Are promising as the rotation state detection means, but there are sufficient proposals as a method for controlling the rotation state of the resonant optical deflection element driven by wide-angle scanning with high accuracy. Not done.

  The information on the rotation state extracted by the rotation state detection means described above is usually as shown in JP 2001-305471 A, JP 2003-177347 A, JP 2003-66360 A, and the like. It is input to a CPU or microcomputer, processed into a drive control signal after arithmetic processing.

  For example, in the technique disclosed in Japanese Patent Application Laid-Open No. 2003-66360, the output drive control signal is generated within one cycle formed through a D / A converter (may be abbreviated as DAC) 54 as shown in FIG. This is a voltage signal 55 having a rectangular waveform with a periodic waveform having a voltage value of zero during a certain period and having a frequency approximately equal to the resonance frequency of the movable part. The output rectangular wave voltage signal 55 is amplified by the driver amplifier 56 and then input to the drive coil to control the rotation of the light deflection element 57. In order to control the scanning angle, it is conceivable to control the amplitude of the voltage signal of the analog waveform to be formed. The voltage signal ranges from the LO level to the HI level (hereinafter, representative values are LO level = 0V, HI level = + 5V). For example, when an 8-bit D / A converter 54 is used, an amplitude V (t) of 256 gradations can be expressed. That is, the scanning amplitude can be controlled with a minimum resolution of about 1/256. However, in this method, when the rotation state of the optical deflection element is controlled by amplitude control of the voltage signal, the amplitude center voltage level of the voltage signal fluctuates. The offset value of t) varies. As a result, the offset fluctuation in the scanning region and the instability of the rotation state occur, which makes it difficult to perform high-precision drive control. In addition, since only a drive signal formed with only a positive bias can be applied, the scanning angle is limited to about half compared with the case where a drive signal formed with a positive and negative bias is used, as described above. is there.

  In order to solve the above-mentioned problem, a method of setting the output drive control signal 58 to a desired analog waveform such as a rectangular wave or a sine wave formed through a D / A converter 59 as shown in FIG. It is done. The formed analog waveform 58 can be freely formed within the range from the LO level to the HI level (hereinafter, considering the case where the LO level = 0V and the HI level = + 5V as representative values), for example, an 8-bit D / A converter When 59 is used, 256 gradations can be expressed. In order to control the scanning angle, it is conceivable to control the amplitude V (t) of the analog waveform 58 to be formed. For example, an analog waveform formed with +2.5 V as the amplitude center is promising. By fixing, the above-described problem of offset fluctuation can be avoided. The output analog waveform 58 is processed by the level shift circuit 60 so that the amplitude center voltage becomes 0 V, then amplified by the amplifier circuit 61, and input to the drive coil to control the rotation of the optical deflection element 62. According to this method, since the drive signal 63 input to the drive coil can be used with both positive and negative biases, the above-described problem of limiting the scanning angle can also be avoided. However, since it is necessary to control the positive and negative amplitudes at the same time in order to solve the above-described offset fluctuation problem, when the 8-bit D / A converter is used, the control of the amplitude V (t) is 128 minutes. 1 minimum resolution. Further, in the method of forming the desired analog waveform, it is necessary to apply an expensive high-performance CPU or high-performance microcomputer, and there is a problem that the system becomes expensive. In order to achieve higher accuracy, it is necessary to increase the number of input bits of the D / A converter, but this further increases the cost of the system.

  On the other hand, for example, in a laser projection system, there is a strong demand for an optical deflecting element that has a wide angle of view and can be adapted to high-definition drawing, that is, light that can operate at a wider angle and realize more accurate rotation state control. There is a strong demand for deflection elements.

  As described above, an effective driving method of an inexpensive resonant optical deflection element that can control the rotation state such as the scanning speed and the scanning angle with high accuracy and can realize wide-angle driving has not been proposed.

  The present invention has been made under such circumstances, and it is an object of the present invention to provide an inexpensive drive control device for a resonant optical deflection element capable of controlling the rotation state with high accuracy and realizing wide-angle driving. It is what.

  In order to solve the above problems, in the present invention, a drive control device for a resonance type optical deflection element is configured as described in the following (1) to (7).

(1) a rotation state signal input terminal for inputting a rotation state signal indicating the rotation state of the resonant optical deflection element;
A comparator that outputs a drive signal to the resonant optical deflection element;
A reference voltage generating means for supplying a reference voltage to one input terminal of the comparator;
A frequency controller that generates a frequency control signal for controlling a resonance frequency of the resonant optical deflection element based on a rotation state signal input to the rotation state signal input end;
A clock signal generating means for generating a clock signal whose frequency is controlled by a frequency control signal generated by the frequency controller, and supplying the clock signal to the other input terminal of the comparator;
A first amplitude controller that generates a digital signal whose amplitude is controlled based on a rotation state signal input to the rotation state signal input end;
The digital signal generated by the first amplitude controller is supplied to one power supply voltage input terminal of the comparator via the first D / A converter, and the digital signal generated by the first amplitude controller is supplied to the second First power supply voltage supply means for supplying to the other power supply voltage input terminal of the comparator via a D / A converter;
The drive control apparatus of the resonance type | mold optical deflection | deviation element provided with.

(2) a rotation state signal input terminal for inputting a rotation state signal indicating the rotation state of the resonant optical deflection element;
A comparator that outputs a drive signal to the resonant optical deflection element;
A reference voltage generating means for supplying a reference voltage to one input terminal of the comparator;
A frequency controller that generates a frequency control signal for controlling the frequency based on the rotation state signal input to the rotation state signal input end;
A clock signal generating means for generating a clock signal whose frequency is controlled by a frequency control signal generated by the frequency controller, and supplying the clock signal to the other input terminal of the comparator;
A first amplitude controller that generates a digital signal whose amplitude is controlled based on a rotation state signal input to the rotation state signal input end;
A digital signal generated by the first amplitude controller is supplied to one power supply voltage input terminal of the comparator via a third D / A converter, and the digital signal generated by the first amplitude controller is supplied to the third signal. Second power supply voltage supply means for supplying the other power supply voltage input terminal of the comparator via the D / A converter and the inverting amplifier circuit;
The drive control apparatus of the resonance type | mold optical deflection | deviation element provided with.

(3) a rotation state signal input terminal for inputting a rotation state signal indicating the rotation state of the resonant light deflection element;
A comparator that outputs a drive signal to the resonant optical deflection element;
A reference voltage generating means for supplying a reference voltage to one input terminal of the comparator;
A frequency controller that generates a frequency control signal for controlling the frequency based on the rotation state signal input to the rotation state signal input end;
A clock signal generating means for generating a clock signal whose frequency is controlled by a frequency control signal generated by the frequency controller, and supplying the clock signal to the other input terminal of the comparator;
A first amplitude controller that generates a digital signal whose amplitude is controlled based on a rotation state signal input to the rotation state signal input end;
A first addition circuit that adds a predetermined analog value and an analog value obtained by converting the digital signal generated by the first amplitude controller by a fourth D / A converter;
The output of the first adder circuit is supplied to one power supply voltage input terminal of the comparator, and the output of the first adder circuit is supplied to the other power supply voltage input terminal of the comparator via an inverting amplifier circuit. Three power supply voltage supply means;
The drive control apparatus of the resonance type | mold optical deflection | deviation element provided with.

(4) In the drive control device for the resonance type optical deflection element according to (3),
The drive control apparatus for a resonant optical deflection element, wherein the predetermined analog value is a changeable value.

(5) In the drive control device for a resonant optical deflection element according to (3) or (4),
The predetermined analog value is supplied to the first adding circuit through a first voltage dividing circuit, and the analog value converted by the fourth D / A converter is supplied to the first adding circuit through a second voltage dividing circuit. A drive control device for a resonant optical deflection element supplied to one adder circuit.

(6) In the drive control device for the resonance type optical deflection element according to (5),
By setting the voltage dividing ratio of the first voltage dividing circuit and the voltage dividing ratio of the second voltage dividing circuit to respective required values, the predetermined analog value is used for coarse control, and the fourth D / D A drive control device for a resonant optical deflection element that uses an analog value converted by an A converter for fine control.

(7) a rotation state signal input terminal for inputting a rotation state signal indicating the rotation state of the resonant optical deflection element;
A comparator that outputs a drive signal to the resonant optical deflection element;
A reference voltage generating means for supplying a reference voltage to one input terminal of the comparator;
A frequency controller that generates a frequency control signal for controlling the frequency based on the rotation state signal input to the rotation state signal input end;
A clock signal generating means for generating a clock signal whose frequency is controlled by a frequency control signal generated by the frequency controller, and supplying the clock signal to the other input terminal of the comparator;
A second amplitude controller that generates a digital signal whose amplitude is controlled based on the rotation state signal input to the rotation state signal input end;
A third voltage dividing circuit for dividing a predetermined analog value;
A fourth voltage dividing circuit for dividing an analog value obtained by converting the digital signal generated by the second amplitude controller by a fifth D / A converter;
A second adding circuit for adding the output of the third voltage dividing circuit and the output of the fourth voltage dividing circuit;
A third amplitude controller for generating a digital signal whose amplitude is controlled based on the rotation state signal input to the rotation state signal input end;
A fifth voltage dividing circuit for dividing a predetermined analog value;
A sixth voltage dividing circuit for dividing an analog value obtained by converting the digital signal generated by the third amplitude controller by a sixth D / A converter;
A third adding circuit for adding the output of the fifth voltage dividing circuit and the output of the sixth voltage dividing circuit;
Fourth power supply means for supplying the output of the second adder circuit to one power supply voltage input terminal of the comparator and supplying the output of the third adder circuit to the other power supply voltage input terminal of the comparator When,
The drive control apparatus of the resonance type | mold optical deflection | deviation element provided with.

  According to the present invention, it is possible to provide an inexpensive drive control device for a resonant optical deflection element that can control the rotation state with high accuracy and realize wide-angle driving.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to an example of “a drive control device for a resonance type optical deflection element”.

  FIG. 1 is a block diagram illustrating a configuration of a “resonance type optical deflection element drive control apparatus” according to the first embodiment. In this embodiment, a resonance type electromagnetic driving light deflection element is assumed as the resonance type light deflection element, but the same can be applied to a resonance type piezoelectric driving light deflection element.

  In FIG. 1, the clock signal output from the clock signal generation means 2 is input to the signal input terminal 4 of the comparator 3, and the comparison voltage signal output from the reference voltage generation means 5 is input to the comparison signal input terminal 6 of the comparator 3. input. The voltage value of the comparison voltage is set to a value larger than the minimum value of the clock signal and smaller than the maximum value. For example, the comparison voltage signal is a constant voltage signal that is approximately half the maximum amplitude value of the clock signal. is there. The frequency of the clock signal substantially coincides with the natural resonance frequency of the movable part determined by the size, shape, and weight of the movable part of the resonant light deflection element, and the size, shape, and material of the torsion bar. The output voltage of the comparator 3 serving as a drive signal for the resonant optical deflection element is a rectangular wave signal whose frequency substantially matches the inherent resonant frequency of the movable part, and the resonant optical deflection element is driven to resonance. Since the resonant optical deflection element itself has a mechanical frequency filter characteristic, when driven near the resonant frequency, the response of the resonant optical deflection element is almost sinusoidal even if the drive waveform is a rectangular wave. This is as described above. The positive amplitude of the output voltage of the comparator 3 serving as a drive signal for the resonant optical deflection element is determined by the positive voltage 8 input to the positive power supply voltage input terminal 7 of the comparator 3, and the comparator The negative amplitude of the output voltage 3 is determined by the negative voltage 10 input to the negative power supply voltage input terminal 9 of the comparator 3.

  The positive voltage input to the positive power supply voltage input terminal 7 of the comparator 3 and the negative voltage input to the negative power supply voltage input terminal 9 of the comparator 3 are detected by the rotation state detecting means 11. The rotation state signal 12 is processed by the amplitude controller 13 and corresponds to the amplitude control voltages 14 and 15 that are modulated and controlled so that the scanning amplitude becomes a desired value. The amplitude controller 13 extracts the scanning amplitude information of the resonance type optical deflection element from the rotation state signal 12 detected by the rotation state detection means 11 and compares it with a predetermined amplitude value to generate a required feedback signal. Since the amplitude controller 13 can obtain sufficient control accuracy by using the comparator 3 having a configuration described later, it is not necessary to apply an expensive high-performance CPU or high-performance microcomputer, and a normal CPU or microcomputer. Can be configured.

  The rotation state detecting means 11 may use a method of using the induced electromotive force generated in the drive coil, a method of adding a detection coil, or a method of detecting a strain amount by applying a strain gauge. An optical sensor such as a photodiode may be provided in the optical scanning area and the optical signal may be detected directly, or an optical fiber may be provided in the optical scanning area to guide the optical signal to the optical sensor and detect the optical signal. good. At this time, it goes without saying that the scanning position information can be obtained from the time-axis component of the optical signal, and the scanning frequency can be extracted by measuring the frequency of the optical signal. Further, the scanning amplitude information can be extracted such that the time during which the optical sensor is irradiated with light, specifically the pulse width of the optical signal, the pulse width decreases as the scanning angle increases. The number of optical sensors to be deployed is not limited to one, and by deploying a plurality of optical sensors, an average value of a plurality of optical signals obtained can be calculated, and a more accurate rotation state can be detected. For example, in the desired optical scanning area, two optical sensors are arranged so as to be symmetric in the scanning direction, and the pulse widths of the two types of optical signals obtained are compared or the interval between the two types of pulses is calculated. By doing so, it is also possible to extract the offset deviation information in the rotating state.

  According to this embodiment, the rotation state signal 12 detected by the rotation state detection unit 11 is processed by the frequency controller 16 and feedback control is performed via the clock signal generation unit 2 so that the scanning frequency becomes a desired value. The scanning frequency of the resonant optical deflection element can be controlled by the frequency of the clock signal 17 thus generated. In this embodiment, since the comparator is used, the clock signal 17 may be a so-called TTL level digital pulse signal such as a rectangular wave signal having a maximum amplitude value = + 5 V and a minimum amplitude value = 0 V, which is expensive. An inexpensive and simple system can be realized without requiring a high-performance CPU or a high-performance microcomputer.

  Further, according to the present embodiment, the rotation state detection signal 12 detected by the rotation state detection means 11 is digitally processed by the amplitude controller 13, and the scanning amplitude is desired via the D / A converter and the amplifier circuit. The amplitude control voltages 14 and 15 that are feedback-controlled so as to have a value of V are modulated and input to the positive power source voltage, the negative power source voltage, or both the positive and negative power source voltages of the comparator 3. As a result, the rectangular wave output voltage signal of the comparator 3 that becomes the drive signal 18 of the resonant optical deflection element can be formed by using both positive and negative biases, so that the resonant type can operate at a wide angle without limiting the scanning angle. A drive control device for the optical deflection element can be provided. Furthermore, when an 8-bit D / A converter is used, it is possible to provide a high-precision drive control device capable of expressing positive and negative amplitudes in 256 gradations, that is, capable of expressing 512 gradations in total amplitude. Therefore, it is possible to easily provide a highly accurate drive control device without increasing the number of input bits of the D / A converter.

  Furthermore, according to this embodiment, the positive voltage 8 input to the positive power supply voltage input terminal 7 of the comparator 3 and the negative voltage 10 input to the negative power supply voltage input terminal 9 are independent of each other. Since it can be controlled, offset control in a rotating state is also possible, and a highly accurate drive control device that can stably maintain the center of the scanning amplitude without changing the offset value of the scanning amplitude can be provided.

  Specifically, based on the offset deviation information of the rotation state obtained by the rotation state detection means 11, for example, when offset deviation information is detected in the positive direction, the positive voltage 8 is controlled to decrease. Alternatively, the negative voltage 10 is controlled to increase in the negative direction, or these controls are combined, and the positive voltage 8 is feedback-controlled, or the negative voltage 10 is feedback-controlled, or the positive voltage 8 and This can be realized by feedback control of the negative voltage 10 together.

  As described above, according to the present embodiment, the rectangular wave output voltage signal of the comparator 3 can be formed by using both positive and negative biases. Therefore, the resonant light that can operate at a wide angle without limiting the scanning angle. A drive control device for a deflection element can be provided. When an 8-bit D / A converter is used, positive and negative amplitudes can be expressed in 256 gradations at the same time, and the conventional technique when an 8-bit D / A converter is used is used. A high-precision drive control device having twice the resolution can be provided, and a high-precision drive control device can be easily provided without increasing the number of input bits of the D / A converter.

  FIG. 2 is a block diagram illustrating a configuration of a “resonance type optical deflection element drive control apparatus” according to the second embodiment. As in the first embodiment, the clock signal 17 output from the clock signal generating means 2 is input to the signal input terminal 4 of the comparator 3, and the comparison voltage signal output from the reference voltage generating means 5 is used as the comparison signal of the comparator 3. Input to the input terminal 6. Thereby, the scanning frequency of the resonant optical deflection element is controlled by the frequency of the clock signal 17 which is a TTL level digital pulse signal which is feedback controlled so that the scanning frequency becomes a desired value via the clock signal generating means 2. It is possible to realize an inexpensive and simple system that does not require an expensive high-performance CPU or high-performance microcomputer.

  Further, as in the first embodiment, the positive amplitude of the output voltage of the comparator 3 that becomes the drive signal 18 of the resonant optical deflection element is a positive voltage input to the positive power supply voltage input terminal 21 of the comparator 3. 20 and the negative amplitude of the output voltage of the comparator 3 is determined by the negative voltage input to the negative power supply voltage input terminal 23 of the comparator 3. According to this embodiment, The first voltage 20 which is calculated and processed by the amplitude controller 13 so that the rotation state signal 12 detected by the rotation state detection means 11 is controlled to have a desired value, has the polarity of the comparator 3. The matching first power supply voltage input terminal 21 is input. The first voltage 20 is input to the inverting amplifier circuit 22 at the same time, and the reverse polarity voltage output from the inverting amplifier circuit 22 is a desired second power supply voltage input terminal that matches the polarity of the comparator 3. 23. For example, when the first voltage 20 that is modulated and controlled so that the scanning amplitude becomes a desired value is a positive voltage, the first voltage 20 is input to the positive power supply voltage input terminal of the comparator 3. At the same time, the first voltage 20 is configured to be input to the negative power supply voltage input terminal 23 of the comparator 3 through the inverting amplifier circuit 22.

  As described above, according to the present embodiment, the rectangular wave output voltage signal of the comparator 3 can be formed by using both positive and negative biases. Therefore, the resonant light that can operate at a wide angle without limiting the scanning angle. A drive control device for a deflection element can be provided. When an 8-bit D / A converter is used, positive and negative amplitudes can be expressed in 256 gradations at the same time, and the conventional technique when an 8-bit D / A converter is used is used. A high-precision drive control device having twice the resolution can be provided, and a high-precision drive control device can be easily provided without increasing the number of input bits of the D / A converter.

  Further, according to the present embodiment, compared with the drive control device 1 of the first embodiment, one control voltage generating means including a D / A converter can be omitted, so that it is possible to drive a cheaper and simpler resonant optical deflection element. A control device can be provided.

  Furthermore, according to the present embodiment, since the positive and negative voltages input to the positive and negative power supply voltage input terminals of the comparator 3 can be simultaneously subjected to amplitude modulation control, they can be stably maintained without changing the offset value of the scanning amplitude. . The amplification factor of the inverting amplifier circuit 22 is normally set to 1. However, when the offset state is desired to be adjusted, it can be realized by adjusting the amplification factor of the inverting amplifier circuit 22.

  FIG. 3 is a block diagram illustrating a configuration of a “resonance type optical deflection element drive control apparatus” according to the third embodiment. Also in the present embodiment, as in the first and second embodiments, the clock signal 17 output from the clock signal generating means 2 is input to the signal input terminal 4 of the comparator 3 and output from the reference voltage generating means 5. The comparison voltage signal is input to the comparison signal input terminal 6 of the comparator 3. Thereby, the scanning frequency of the resonant optical deflection element is controlled by the frequency of the clock signal 17 which is a TTL level digital pulse signal which is feedback controlled so that the scanning frequency becomes a desired value via the clock signal generating means 2. It is possible to realize an inexpensive and simple system that does not require an expensive high-performance CPU or high-performance microcomputer.

  Also in this embodiment, by applying the inverting amplifier circuit 22 as in the second embodiment, it is possible to provide an inexpensive and simple system that can be stably maintained without changing the offset value of the scanning amplitude. Since the rectangular-wave output voltage signal of the comparator 3 can be formed by using both positive and negative biases, it is possible to provide a drive control device for a resonance type optical deflection element that can operate at a wide angle without limiting the scanning angle.

  Further, in this embodiment, the rotation state signal 12 detected by the rotation state detection means 11 is processed by the amplitude controller 13 and modulated via the D / A converter 25 so that the scanning amplitude becomes a desired value. The first amplitude control voltage 26 and the second amplitude control voltage 27 modulated and controlled to a desired value by the amplitude controller 13 are input to the input terminal of the first summing amplifier circuit 28, and the first The controlled third voltage 29 output from the summing amplifier circuit 28 is configured to be the controlled first voltage 20 in the second embodiment. With this configuration, the amplitude control resolution can be improved.

  Specifically, for example, the first amplitude control voltage 26 is set to a constant voltage of +5 V, and the second amplitude is controlled so that the scanning amplitude becomes a desired value via an 8-bit D / A converter. When the output range of the amplitude control voltage 27 is set to be 0 V to +5 V and the amplification factor of the first addition amplifier circuit 28 is set to 1 time, the output of the controlled third voltage 29 is from +5 V. The range of +10 V can be expressed with 256 gradations, and double the resolution can be obtained as compared with the drive control device 19 according to the second embodiment, and it is easy without increasing the number of input bits of the D / A converter. In addition, a highly accurate drive control device can be provided. At this time, since the first amplitude control voltage 26 is a constant voltage, it goes without saying that the control from the amplitude controller 13 and the D / A converter can be omitted. The first amplitude control voltage 26 is not limited to a constant voltage. For example, when the modulation control can be performed in a range from 0 V to +5 V, the control range of the controlled third voltage 29 is widened. be able to.

  As described above, according to the present embodiment, it is possible to provide a drive control device for a resonant optical deflection element with higher accuracy than that of the second embodiment by adding a simple configuration.

  FIG. 4 is a block diagram illustrating a configuration of a “resonance type optical deflection element drive control apparatus” according to a fourth embodiment. This embodiment can realize higher accuracy control than the third embodiment.

  Since the configuration of the drive control device 30 according to the fourth embodiment is substantially the same as the configuration of the drive control device 24 described in the third embodiment, the details thereof will be omitted. However, the drive control device 30 according to the present embodiment has a configuration according to the third embodiment. Compared to the configuration of the drive control device 24, the first amplitude control voltage 26 and the second amplitude control voltage 27 are respectively transmitted through the first voltage dividing circuit 31 and the second voltage dividing circuit 32. The input to the first summing amplifier circuit 28 is improved.

  By adopting this configuration, it is possible to dramatically improve the amplitude control accuracy of the resonance type optical deflection element.

  Specifically, for example, the first amplitude control voltage 26 is set to a constant voltage of + 5V, and the second amplitude control voltage 27 is set within a range of 0V to + 5V via an 8-bit D / A converter 25. When the voltage is controlled so that it can be modulated with 256 gradations, the voltage dividing ratio of the first voltage dividing circuit 31 is 1, and the voltage dividing ratio of the second voltage dividing circuit 32 is 0.1. The controlled third voltage 33 output from one summing amplifier circuit 28 can be a voltage capable of expressing 256 gradations in the range from +5 V to +5.5 V, and increases the number of input bits of the D / A converter. Therefore, the amplitude drive accuracy can be easily and dramatically improved. At this time, since the first amplitude control voltage 26 is a constant voltage, it goes without saying that the control from the amplitude controller 13 and the D / A converter can be omitted. The setting of the voltage division ratio is not limited to 0.1, but is set to a desired value according to the purpose of the system. For example, the drive control accuracy is further improved by setting the voltage division ratio to 0.05. Alternatively, the drive control range may be expanded by setting the partial pressure ratio to 0.5. Further, the first amplitude control voltage 26 is not limited to a constant voltage. For example, when the modulation control can be performed in a range from 0 V to +5 V, the control range of the controlled third voltage 33 is widened. Furthermore, the first amplitude control voltage 26 can be set by setting the voltage dividing ratio of the first voltage dividing circuit 31 and the voltage dividing ratio of the second voltage dividing circuit 32 to desired values, respectively. It is possible to use the second amplitude control voltage 27 for fine control for coarse control.

  As described above, according to this embodiment, it is possible to provide a drive control device for a resonant optical deflection element with higher accuracy than that of Embodiment 3 by adding a simple configuration.

  FIG. 5 is a block diagram illustrating a configuration of a “resonant light deflection element drive control apparatus” according to the fifth embodiment. In the fifth embodiment, the configuration in which the voltage control accuracy is dramatically improved by using the voltage dividing circuit described in the fourth embodiment is different from the configuration in which power is supplied to the positive and negative power supply voltage input terminals of the comparator. Further, the inverting amplifier circuit 22 used in the second, third, and fourth embodiments is omitted, and the positive and negative power supply voltages of the comparators can be controlled independently.

  Also in this embodiment, as in the first to fourth embodiments, the clock signal 17 output from the clock signal generating means 2 is input to the signal input terminal 4 of the comparator 3 and output from the reference voltage generating means 5. The comparison voltage signal is input to the comparison signal input terminal 6 of the comparator 3. Thereby, the scanning frequency of the resonant optical deflection element is controlled by the frequency of the clock signal 17 which is a TTL level digital pulse signal which is feedback controlled so that the scanning frequency becomes a desired value via the clock signal generating means 2. It is possible to realize an inexpensive and simple system that does not require an expensive high-performance CPU or high-performance microcomputer.

  Also in the present embodiment, the rectangular wave output voltage signal of the comparator 3 can be formed by using both positive and negative biases, so that the drive control device for the resonance type optical deflection element capable of operating at a wide angle without limiting the scanning angle. Can provide.

  Further, according to the present embodiment, the third to sixth voltage dividing circuits 35, 36, 37, and 38 are appropriately set without dividing the D / A converter without increasing the number of input bits. High-accuracy drive that easily realizes high-resolution amplitude control and also enables rotational offset control with high resolution, and can stably maintain the center of scanning amplitude without changing the offset value of scanning amplitude. A control device can be provided.

  As described above, according to the present embodiment, the rotational state can be increased without applying an expensive high-performance CPU or high-performance microcomputer, and without increasing the number of input bits of the D / A converter. A drive control device for a resonant optical deflection element that can be controlled with high accuracy can be provided at low cost.

  In addition, it is possible to provide a drive control device for a resonant optical deflection element that can operate at a wide angle without limiting the scanning angle and can control the rotation state with high accuracy. Furthermore, it is possible to provide a drive control device for a resonant optical deflection element that can maintain the scanning amplitude center stably and can control the rotational state of the resonant optical deflection element with high accuracy without changing the offset value of the scanning amplitude.

Block diagram showing the configuration of the first embodiment The block diagram which shows the structure of Example 2. The block diagram which shows the structure of Example 3. The block diagram which shows the structure of Example 4. Block diagram showing the configuration of the fifth embodiment The perspective view which shows the structure of an electromagnetic drive light deflection | deviation element Operation explanatory diagram of electromagnetically driven light deflection element Operation explanatory diagram of electromagnetically driven light deflection element The figure which shows the drive characteristic of an electromagnetic drive light deflection element Diagram explaining the problems of the prior art Diagram explaining the problems of the prior art

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Drive control apparatus 2 which is Example 1 Clock signal generation means 3 Comparator 4 Comparator signal input terminal 5 Reference voltage generation means 6 Comparator comparison signal input terminal 7 Comparator positive power supply voltage input terminal 9 Comparator negative power supply voltage Input terminal 11 Rotation state detection means 13 Amplitude controller 16 Frequency controller

Claims (7)

A rotation state signal input terminal for inputting a rotation state signal indicating the rotation state of the resonant light deflection element;
A comparator that outputs a drive signal to the resonant optical deflection element;
A reference voltage generating means for supplying a reference voltage to one input terminal of the comparator;
A frequency controller that generates a frequency control signal for controlling a resonance frequency of the resonant optical deflection element based on a rotation state signal input to the rotation state signal input end;
A clock signal generating means for generating a clock signal whose frequency is controlled by a frequency control signal generated by the frequency controller, and supplying the clock signal to the other input terminal of the comparator;
A first amplitude controller that generates a digital signal whose amplitude is controlled based on a rotation state signal input to the rotation state signal input end;
The digital signal generated by the first amplitude controller is supplied to one power supply voltage input terminal of the comparator via the first D / A converter, and the digital signal generated by the first amplitude controller is supplied to the second First power supply voltage supply means for supplying to the other power supply voltage input terminal of the comparator via a D / A converter;
A drive control apparatus for a resonant optical deflection element, comprising: A rotation state signal input terminal for inputting a rotation state signal indicating the rotation state of the resonant light deflection element;
A comparator that outputs a drive signal to the resonant optical deflection element;
A reference voltage generating means for supplying a reference voltage to one input terminal of the comparator;
A frequency controller that generates a frequency control signal for controlling the frequency based on the rotation state signal input to the rotation state signal input end;
A clock signal generating means for generating a clock signal whose frequency is controlled by a frequency control signal generated by the frequency controller, and supplying the clock signal to the other input terminal of the comparator;
A first amplitude controller that generates a digital signal whose amplitude is controlled based on a rotation state signal input to the rotation state signal input end;
A digital signal generated by the first amplitude controller is supplied to one power supply voltage input terminal of the comparator via a third D / A converter, and the digital signal generated by the first amplitude controller is supplied to the third signal. Second power supply voltage supply means for supplying the other power supply voltage input terminal of the comparator via the D / A converter and the inverting amplifier circuit;
A drive control apparatus for a resonant optical deflection element, comprising: A rotation state signal input terminal for inputting a rotation state signal indicating the rotation state of the resonant light deflection element;
A comparator that outputs a drive signal to the resonant optical deflection element;
A reference voltage generating means for supplying a reference voltage to one input terminal of the comparator;
A frequency controller that generates a frequency control signal for controlling the frequency based on the rotation state signal input to the rotation state signal input end;
A clock signal generating means for generating a clock signal whose frequency is controlled by a frequency control signal generated by the frequency controller, and supplying the clock signal to the other input terminal of the comparator;
A first amplitude controller that generates a digital signal whose amplitude is controlled based on a rotation state signal input to the rotation state signal input end;
A first addition circuit that adds a predetermined analog value and an analog value obtained by converting the digital signal generated by the first amplitude controller by a fourth D / A converter;
The output of the first adder circuit is supplied to one power supply voltage input terminal of the comparator, and the output of the first adder circuit is supplied to the other power supply voltage input terminal of the comparator via an inverting amplifier circuit. Three power supply voltage supply means;
A drive control apparatus for a resonant optical deflection element, comprising: In the drive control apparatus of the resonance type optical deflection element according to claim 3,
The drive control apparatus for a resonance type optical deflection element, wherein the predetermined analog value is a changeable value. In the drive control apparatus of the resonance type optical deflection element according to claim 3 or 4,
The predetermined analog value is supplied to the first adding circuit through a first voltage dividing circuit, and the analog value converted by the fourth D / A converter is supplied to the first adding circuit through a second voltage dividing circuit. A drive control apparatus for a resonance type optical deflection element, characterized in that the drive circuit is supplied to one adding circuit. In the drive control apparatus of the resonance type optical deflection element according to claim 5,
By setting the voltage dividing ratio of the first voltage dividing circuit and the voltage dividing ratio of the second voltage dividing circuit to respective required values, the predetermined analog value is used for coarse control, and the fourth D / D An analog value converted by the A converter is used for fine control. A rotation state signal input terminal for inputting a rotation state signal indicating the rotation state of the resonant light deflection element;
A comparator that outputs a drive signal to the resonant optical deflection element;
A reference voltage generating means for supplying a reference voltage to one input terminal of the comparator;
A frequency controller that generates a frequency control signal for controlling the frequency based on the rotation state signal input to the rotation state signal input end;
A clock signal generating means for generating a clock signal whose frequency is controlled by a frequency control signal generated by the frequency controller, and supplying the clock signal to the other input terminal of the comparator;
A second amplitude controller that generates a digital signal whose amplitude is controlled based on the rotation state signal input to the rotation state signal input end;
A third voltage dividing circuit for dividing a predetermined analog value;
A fourth voltage dividing circuit for dividing an analog value obtained by converting the digital signal generated by the second amplitude controller by a fifth D / A converter;
A second adding circuit for adding the output of the third voltage dividing circuit and the output of the fourth voltage dividing circuit;
A third amplitude controller for generating a digital signal whose amplitude is controlled based on the rotation state signal input to the rotation state signal input end;
A fifth voltage dividing circuit for dividing a predetermined analog value;
A sixth voltage dividing circuit for dividing an analog value obtained by converting the digital signal generated by the third amplitude controller by a sixth D / A converter;
A third adding circuit for adding the output of the fifth voltage dividing circuit and the output of the sixth voltage dividing circuit;
Fourth power supply means for supplying the output of the second adder circuit to one power supply voltage input terminal of the comparator and supplying the output of the third adder circuit to the other power supply voltage input terminal of the comparator When,
A drive control apparatus for a resonant optical deflection element, comprising:

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