JP2004062083A - Scanner motor and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the influence of noise and to surely transmit an FG (frequency generator) signal to a controller in a scanner motor for rotating a polygon mirror by a drive signal for controlling a rotation speed transmitted from a driving circuit of a separate body and its control method. <P>SOLUTION: The scanner motor 10 is provided with a frequency generator coil 32 and an amplifier 34 for amplifying the FG signal. In the amplifier 34, high-frequency components are removed from the FG signal by a low-pass filter 58 and the FG signal is amplified and is made into a binary level by a comparator 60. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a scanner motor that transmits a drive signal for controlling the rotational speed from a separate drive circuit, and rotates a polygon mirror by the drive signal, and a control method thereof, and a scanner motor that transmits an FG signal to the drive circuit. And a control method thereof.
[0002]
[Prior art]
In a laser printer, a laser copy, or the like, a scanner motor that rotates a polygon mirror is used as means for main scanning with laser light. For the scanner motor, efforts are made to rotate the polygon mirror at a high speed for the purpose of speeding up the processing. Since the high-speed rotation type scanner motor is relatively small, it can be mounted on a drive circuit board that controls rotation.
[0003]
On the other hand, there is a need to rotate the polygon mirror at a low speed in order to perform main scanning with high accuracy. In order to rotate the polygon mirror at a low speed and reduce the jitter (unevenness of the rotational speed), it is necessary to stabilize the rotation by sufficiently increasing the moment of inertia. Increasing the moment of inertia means increasing the mass, and the strength of equipment parts such as bearings is also required, resulting in an increase in the size of the scanner motor.
[0004]
As described above, the scanner motor for low-speed rotation is relatively large and cannot be mounted on the drive circuit board, and the scanner motor and the controller including the drive circuit are configured separately.
[0005]
Further, by separating the scanner motor and the controller, the scanner motor does not become extremely large, and the mounting design on the device becomes easy.
[0006]
[Problems to be solved by the invention]
In the controller, the rotation speed of the polygon mirror is controlled by a PLL (Phase Locked Loop) circuit or the like. This PLL circuit requires a polygon mirror rotation signal as a feedback signal, and an FG signal is input from the scanner motor.
[0007]
The FG signal is an AC signal obtained by utilizing the phenomenon that an electromotive force is generated when a frequency power generation coil passes through a magnetic field generated by a frequency power generation magnet. Since the FG signal generates a voltage corresponding to the relative speed between the frequency power generation coil and the frequency power generation magnet, it becomes a weak signal during low-speed rotation.
[0008]
Therefore, if the FG signal indicating the rotation speed is transmitted from the scanner motor to the controller while the polygon mirror is rotating at a low speed, the FG signal is weak, so that the noise resistance is low. In other words, the SN ratio is small. This phenomenon becomes more prominent as the signal line connecting the scanner motor and the controller becomes longer, and the controller may malfunction and increase the polygon mirror rotation jitter. As a result, the main scanning with respect to the sheet member becomes abnormal, and the obtained image is distorted.
[0009]
In order to improve noise resistance, generally, signal line shielding and a method of inserting a ferrite core are employed. However, the effects of these methods are small, and noise cannot be sufficiently removed.
[0010]
The present invention has been made in consideration of such problems. In a scanner motor that transmits a drive signal for controlling a rotation speed from a separate drive circuit and rotates a polygon mirror by the drive signal, and a control method thereof An object of the present invention is to provide a scanner motor that can reduce the influence of noise and reliably transmit an FG signal to a controller, and a control method thereof.
[0011]
[Means for Solving the Problems]
In the scanner motor according to the present invention, a drive signal for controlling the rotation speed is transmitted from a separate drive circuit, and an FG signal corresponding to the rotation speed of the polygon mirror is generated in the scanner motor that rotates the polygon mirror by the drive signal. A frequency generator coil to be generated, and a signal processor that performs signal processing to increase an SN ratio when the FG signal is transmitted, and the signal processed by the signal processor is used as a feedback signal for the rotational speed It transmits to the said drive circuit, It is characterized by the above-mentioned.
[0012]
Thus, since the FG signal is transmitted to the drive circuit after signal processing, the influence of noise on the FG signal can be reduced and the FG signal can be reliably transmitted to the drive circuit.
[0013]
In this case, the signal processor may be an amplifier.
[0014]
In addition, the amplifier can further improve noise resistance by amplifying and digitizing the FG signal.
[0015]
Furthermore, the amplifier can improve noise resistance with a simple circuit by amplifying the FG signal and converting it to a binary level. Further, the processing is simplified and the FG signal can be transmitted at high speed.
[0016]
Further, the amplifier may binarize the FG signal by a comparator and transmit the signal to the drive circuit by an open collector output. By using an open collector output, it can be applied to a wide range of voltage levels.
[0017]
Furthermore, the frequency power generation coil may be set in an annular shape centering on a rotation axis, and the signal processor may be arranged on the outer peripheral side of the electromotive force generation portion of the frequency power generation coil.
[0018]
The frequency power generation coil and the signal processor may be disposed on the same substrate.
[0019]
The rotation speed of the polygon mirror may be in the range of 300 [rpm] to 10000 [rpm].
[0020]
In the scanner motor control method according to the present invention, a drive signal for controlling the rotation speed is transmitted from a separate drive circuit, and the polygon mirror is rotated by the drive signal. A step of generating an FG signal corresponding to the rotation speed by a frequency power generation coil, a step of performing a signal processing for increasing an SN ratio when the FG signal is transmitted by a signal processor, and a signal processing by the signal processor Transmitting the signal to the drive circuit as a feedback signal of the rotational speed.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of a scanner motor and a control method thereof according to the present invention will be described with reference to the accompanying FIGS. 1 to 8B. The scanner motor 10 according to the present embodiment rotates the polygon mirror 52 at a low speed for the purpose of performing high-precision main scanning.
[0022]
As shown in FIGS. 1 and 2, a scanner motor 10 according to the present embodiment includes a stator case 12, a coil substrate 14 that is an annular printed circuit board disposed in the stator case 12, and a harness 16. And a rotating part 22 that rotates around a shaft 20 that extends upward from the center of the stator case 12 as a support shaft.
[0023]
The stator case 12 is formed by, for example, aluminum die casting, and a mounting bolt hole 12a is provided on the periphery. The upper surface of the stator case 12 has multi-stage circular recesses that are stepped deeper toward the center, and an annular stator yoke 24 is bonded to one of the recesses. A thin insulator 26 is provided on the upper surface of the stator yoke 24, and the coil substrate 14 is fixed to the upper surface of the insulator 26 with screws 28. A shaft 20 is press-fitted into the center of the stator case 12, and the shaft 20 extends upward through a hole in the center of the coil substrate 14.
[0024]
The coil substrate 14 includes six coils 30 that generate magnetic force for rotating the rotating unit 22, a frequency power generating coil 32 that detects the rotational speed of the rotating unit 22, and an amplifier 34 that performs signal processing on signals generated by the frequency power generating coil 32. And have. Details of the coil substrate 14 will be described later.
[0025]
The rotating portion 22 is based on a disk-shaped hub 36, and a relatively wide annular rotor yoke 38 is bonded to the lower surface of the hub 36. On the further lower surface of the rotor yoke 38, an annular magnet 40 having the same width as the coil 30 and an annular frequency power generation magnet 42 having a relatively narrow width are bonded. The magnet 40 and the frequency power generation magnet 42 are concentrically arranged, and the magnet 40 is set on the inner peripheral side and the frequency power generation magnet 42 is set on the outer peripheral side.
[0026]
The rotor yoke 38, the magnet 40, and the frequency power generation magnet 42 are bonded to each other and integrated with the hub 36. However, in FIG. 1, the rotor yoke 38, the magnet 40, and the frequency power generation magnet 42 are separated from each other for easy understanding.
[0027]
A vertical hole 36a is provided at the center of the hub 36, and a bearing 44 and a bearing 46 for supporting the shaft 20 are provided at a lower portion and a relatively upper portion of the vertical hole 36a. The shaft 20 is fixed to the inner ring 46 a of the bearing 46 by screws 48. The screw 48 and the top of the shaft 20 are protected by a cover 50.
[0028]
A polygon mirror 52 having six mirror surfaces 52a for deflecting laser light emitted from the outside is fixed by a polygon holder 54 and a retaining ring 56 slightly above the hub 36.
[0029]
The hub 36 is made of, for example, brass and has a relatively large diameter, so that the value of the moment of inertia is large.
[0030]
As shown in FIG. 3, the frequency power generation magnet 42 is magnetically divided into a large number of N poles and S poles according to the pitch of the frequency power generation coil 32. The magnet 40 is also magnetically divided into an N pole and an S pole corresponding to the pitch of the coil 30.
[0031]
As shown in FIG. 2, the magnet 40 and the coil 30 are disposed at positions approaching each other with the coil substrate 14 interposed therebetween. Since the coil substrate 14 allows magnetic flux to pass through and the rotor yoke 38 to which the magnet 40 is bonded acts as a magnetic path, by controlling the magnetic field by the coil 30, each magnetic pole of the magnet 40 is repelled and attracted, The hub 36 to which the magnet 40 and the rotor yoke 38 are bonded rotates around the shaft 20 as an axis. At this time, the polygon mirror 52 fixed to the hub 36 also rotates integrally, and the laser light can be deflected according to the rotation angle. The deflected laser light is continuously applied to a sheet body (not shown) to perform main scanning processing.
[0032]
As shown in FIG. 4, an amplifier 34 and a frequency power generation coil 32 are provided on the upper surface of the coil substrate 14.
[0033]
The frequency power generation coil 32 is a continuous rectangular printed wiring, and is set in an annular shape on the relatively outer peripheral portion of the coil substrate 14. The frequency power generation coil 32 and the frequency power generation magnet 42 have substantially the same radial width. Further, the frequency power generation magnet 42 and the frequency power generation coil 32 are arranged close to each other on the coil substrate 14 (see FIG. 2), and the stator yoke 24 acts as a magnetic path. Magnetic fields generated by the plurality of N poles and S poles of the magnet 42 cross the frequency power generation coil 32 one after another. In this way, the frequency power generation coil 32 generates an AC signal corresponding to the rotational speed, that is, an FG signal. The amplitude and frequency of the FG signal increase as the rotational speed increases, and the amplitude and frequency decrease as the rotational speed decreases. The FG signal generated by the frequency power generation coil 32 is supplied to the amplifier 34 from both ends 32a and 32b of the AC power generation coil.
[0034]
As shown in FIGS. 4 and 5, the amplifier 34 amplifies the low-pass filter 58 that removes unnecessary high-frequency components contained in the FG signal, and a signal that has passed through the low-pass filter 58, and converts it to a binary level. And a comparator 60. As is clear from FIGS. 4 and 5, the amplifier 34 has a simple configuration.
[0035]
The low-pass filter 58 includes a resistor 62 and a capacitor 64 for filtering a signal supplied from one end of the frequency power generation coil 32, a resistor 66 and a capacitor 68 for filtering a signal supplied from the other end of the frequency power generation coil 32, These resistors 62 and 66 and a capacitor 70 are provided between the two signals filtered by the capacitors 64 and 68 and stabilize the signal.
[0036]
The resistor 62 and the resistor 66 have the same resistance value, and the capacitor 64 and the capacitor 68 have the same capacitance value, thus forming a balanced circuit. The cut-off frequency calculated by the resistor 62 (or resistor 66) and the capacitor 64 (or capacitor 68) is set sufficiently higher than the frequency of the FG signal.
[0037]
The comparator 60 is operated by a DC power source V and a ground G supplied from a motor driver (or controller) 80 which is a drive circuit separated from the scanner motor 10. In the vicinity of the comparator 60, a bypass capacitor 72 for smoothing the power supply V is provided. The FG signal that has passed through the low-pass filter 58 is supplied to the “+” input terminal and the “−” input terminal of the comparator 60. Since the comparator 60 is a kind of operational amplifier, it amplifies the signal inside and compares the signal. As a result of this comparison, the FG signal is binarized by the magnitude relationship between the voltage values of the “+” input terminal and the “−” input terminal. The comparator 60 is an open collector output. When the voltage at the “+” input terminal is larger than the voltage at the “−” input terminal, the output is turned on, and the voltage at the “+” input terminal is “−”. The output is turned off when the voltage is lower than the voltage at the input terminal. The output of the comparator 60, that is, a signal set to have a large SN ratio so as to be suitable for signal transmission is transmitted to the motor driver 80 via the harness 16 and the connector 18. When the output of the comparator 60 is an output type having hysteresis, noise resistance is further improved.
[0038]
Inside the motor driver 80, the output signal of the comparator 60 is pulled up to the power supply V by the resistor 82. As a result, when the output of the comparator 60 is on, the voltage is 0 [V], and when the output of the comparator 60 is off, the voltage is the same as that of the power supply V. The electromotive force of the frequency power generation coil 32 is generally about several tens [mV]. For example, if the voltage of the power supply V is set to 5 [V], the output of the comparator 60 becomes a signal of 0 [V] or 5 [V], and a sufficient amplification factor is obtained by the action of the amplifier.
[0039]
Each of the comparators 60 and the like constituting the amplifier 34 is a surface mount type element, and is disposed on the outer peripheral side of the frequency power generation coil 32. Specifically, the printed pattern of the frequency power generation coil 32 is located on the outer peripheral side of the printed pattern of the frequency power generation coil 32 facing the frequency power generation magnet 42 (see FIG. 3) and on the outer peripheral end of the coil substrate 14. It is arranged on the circumferential side. By arranging the amplifier 34 on the outer peripheral side of the frequency power generation coil 32 in this way, the electrical action of the amplifier 34 and the electromagnetic action of the frequency power generation coil 32 and the frequency power generation magnet 42 are prevented from interfering with each other. it can.
[0040]
Further, by arranging the amplifier 34 on the outer peripheral side of the frequency power generation coil 32, there is no obstacle between the frequency power generation coil 32 and the frequency power generation magnet 42, and the frequency power generation coil 32 and the frequency power generation magnet 42 are brought close to each other. Can be provided in position. Furthermore, since the amplifier 34 is arranged on the outer peripheral side of the coil 30 and the magnet 40, the shape, size, arrangement, and electromagnetic performance of the coil 30 and the magnet 40 are not restricted.
[0041]
Furthermore, normally, since the harness 16 is provided on the outer periphery of the coil substrate 14, the distance between the amplifier 34 and the harness 16 can be set to a relatively short distance. Therefore, the printed wiring between the amplifier 34 and the harness 16 can be set short, and the influence of noise can be further reduced.
[0042]
The amplifier 34 may be provided on the back surface of the surface on which the frequency power generation coil 32 is printed. The amplifier 34 and the frequency power generation coil 32 may be provided on separate substrates.
[0043]
As shown in FIG. 6, six coils 30 and three Hall elements 74 are provided on the lower surface of the coil substrate 14. The six coils 30 are arranged at equal intervals so as to form an annulus, and are located under the magnet 40 (see FIG. 2). The three Hall elements 74 are disposed at substantially the center of every other coil 30. One end of the harness 16 is soldered to the plurality of through holes 76 and connected to the connector 18. 4 and 6, detailed printed wiring is not shown.
[0044]
Returning to FIG. 5, the motor driver 80 is based on the resistor 82 that pulls up the output signal of the comparator 60 to the power supply V, the buffer 84 that shapes the output signal, and the output signal of the comparator 60 that passes through the buffer 84. And a motor control circuit 86 for exciting the coils 30 in order. For example, when a Schmitt trigger type element is used for the buffer 84, noise resistance can be further improved. The motor control circuit 86 controls the scanner motor 10 using, for example, a PLL circuit, a speed control circuit, a three-phase logic circuit, or the like.
[0045]
The motor driver 80 also supplies a clock 88 for supplying an oscillation signal serving as a control reference to the motor control circuit 86, and a power supply for generating power V and supplying power to the motor control circuit 86 when power is supplied from the outside. Circuit 90.
[0046]
The motor control circuit 86 is connected to the three Hall elements 74, and can rotate the polygon mirror 52 while detecting the N-pole position and S-pole position of the magnet 40 (see FIG. 2).
[0047]
Next, the operation of rotating the rotating unit 22 and the polygon mirror 52 while the scanner motor 10 configured as described above is controlled by the motor driver 80 will be described with reference to FIGS. 1, 2, and 5.
[0048]
The motor control circuit 86 of the motor driver 80 rotates the rotating unit 22 by sequentially exciting the coils 30 of the scanner motor 10. The frequency power generation magnet 42 rotates integrally with the rotation of the rotating unit 22, and a plurality of N poles and S poles of the frequency power generation magnet 42 sequentially pass over the printed wiring extending in the radial direction of the frequency power generation coil 32. . As a result, the printed wiring of the frequency power generation coil 32 moves relatively in the magnetic field, generates alternating current power and generates an FG signal. The amplitude and frequency of the FG signal are values corresponding to the rotation speed of the rotating unit 22.
[0049]
By the way, the scanner motor 10 according to the present embodiment is of a specification that rotates at a low speed for the purpose of performing highly accurate main scanning. The number of rotations is determined by parameters such as the number of surfaces of the polygon mirror 52 and the width of the sheet body for main scanning. As a general specification, the number of surfaces of the polygon mirror 52 is six, When the body width is 350 [mm], relatively high-precision main scanning can be performed when the rotational speed of the polygon mirror 52 is set to 10000 [rpm] or less.
[0050]
On the other hand, during low-speed rotation of 10000 [rpm] or less, the FG signal output from the frequency power generation coil 32 is a weak signal, and the specific signal level is several tens [mV].
[0051]
The FG signal is supplied to the “+” input terminal and the “−” input terminal of the comparator 60 after unnecessary high frequency components are removed by the low-pass filter 58. The comparator 60 amplifies and compares the FG signals input to the “+” input terminal and the “−” input terminal, and outputs the comparison result in an open collector format. Since the comparator 60 amplifies the FG signal internally, it can be accurately compared if the voltage level difference between the “+” input terminal and the “−” input terminal is several tens [mV]. Further, both end portions 32a and 32b of the frequency power generation coil 32 and the amplifier 34 are provided at positions close to each other, and the both end portions 32a and 32b and the amplifier 34 are substantially covered by the stator case 12, so that they are externally provided. Noise is difficult to mix.
[0052]
The output of the comparator 60 is output as an open collector on or off, and is supplied to the motor driver 80 via the harness 16 and the connector 18. In the motor driver 80, the output signal of the comparator 60 is pulled up to the power supply V by the resistor 82. As a result, the FG signal is binarized to take one of 0 [V] and the power supply V voltage. Signal. Since the power supply V is generally a voltage of 3.3 [V], 5 [V], 12 [V], etc., the FG signal is amplified with a large amplification factor. Therefore, the SN ratio is improved, and so-called immunity performance is improved.
[0053]
Thereby, even if noise is mixed in the harness 16 or the connector 18, the noise is removed by the buffer 84 if the amplitude value of the noise is relatively small with respect to the voltage value of the power supply V. Therefore, an accurate signal is supplied to the motor control circuit 86.
[0054]
In the motor control circuit 86, the binary level signal supplied from the buffer 84 is compared with the oscillation signal of the clock 88, and the coil 30 is excited based on the frequency and phase of each signal. In this way, the FG signal is accurately supplied to the motor control circuit 86 without being affected by noise. Therefore, the rotating unit 22 and the polygon mirror 52 can rotate at a stable speed with little jitter even at a low speed of 10,000 [rpm] or less.
[0055]
In practice, when the rotation is 300 [rpm] or less, the electromotive force of the frequency power generation coil 32 becomes extremely small, the inertia of the rotation becomes small, and the jitter becomes large. Therefore, it is preferable that the rotation speeds of the rotating unit 22 and the polygon mirror 52 are 300 [rpm] or more.
[0056]
The waveforms of the respective parts when signals are transmitted from the scanner motor 10 to the motor driver 80 are as shown in FIG. 8A. That is, the sine wave FG signal generated by the frequency power generation coil 32 is binarized by the comparator 60. This binary level signal becomes a level corresponding to the voltage value of the power supply V supplied from the motor driver 80, and a sufficient amplification factor is obtained. Therefore, the output value of the comparator 60 becomes a relatively large value with respect to noise, the SN ratio is improved, and the noise superimposed on the input signal to the motor driver 80 becomes a relatively small value. Further, when a Schmitt trigger type element is used for the buffer 84 (see FIG. 5) in the motor driver 80, the value of the control signal as the output is not inverted unless the relatively large threshold value 84a is exceeded at the low level. Further, at the high level, the value of the control signal is not inverted unless it falls below a relatively small threshold value 84b. Thus, the output signal of the comparator 60 has a large S / N ratio and noise resistance performance is improved.
[0057]
On the other hand, the waveform of each part when a signal is transmitted by a conventional scanner motor is as shown in FIG. 8B. In this case, since the level of the FG signal is very small, the transmission noise as a disturbance is superimposed as it is, and the input signal to the motor driver 80 has a very distorted waveform. This distortion part exceeds a threshold value when the control signal is shaped relatively frequently, and an error signal 112 is generated in the control signal.
[0058]
In FIGS. 8A and 8B, the vertical axes indicating the voltages are different scales, and in particular, the FG signals in FIGS. 8A and 8B and the input signal to the motor driver 80 in FIG. 8B are larger than other waveforms. Are shown.
[0059]
Next, three modified examples instead of the amplifier 34 of the scanner motor 10 will be described with reference to FIGS. 7A to 7C. Since the low-pass filter 58 in these three modifications has the same configuration as the low-pass filter 58 of the amplifier 34, the corresponding elements are denoted by the same reference numerals and detailed description thereof is omitted.
[0060]
As shown in FIG. 7A, an amplifier 100 according to a first modification is for amplifying a signal supplied from a low-pass filter 58 by an amplifier 102. That is, the signal like the comparator 60 is not subjected to the binary leveling process but is simply amplified and supplied to the motor driver 80. In this way, even if only amplification is performed and binary level conversion is not performed, the SN ratio at the time of signal transmission is improved, so noise resistance can be improved. As the amplifier 102, for example, a differential amplifier circuit or an instrumentation amplifier (instrumentation amplifier) can be employed.
[0061]
In this case, the motor driver 80 may receive the supplied signal by the buffer amplifier, compare it with a predetermined threshold value, convert it to a binary level, and supply it to the motor control circuit 86.
[0062]
As shown in FIG. 7B, an amplifier 104 as a second modified example further converts the output signal of the amplifier 102 into a digital signal by an analog / digital converter 106 (A / D) and then supplies it to the motor driver 80. is there.
[0063]
For example, if an analog / digital converter 106 having an output of 8 [bits] is adopted, the resolution of the FG signal is 256.
[0064]
In this case, the motor driver 80 binarizes the supplied signal by an appropriate decoding circuit, but the most appropriate threshold can be selected and set from 256 levels as the binarization threshold. Further, since the FG signal is transmitted as digital data, it has high noise resistance.
[0065]
As shown in FIG. 7C, an amplifier 108 according to a modification of the third embodiment converts the output of the analog / digital converter 106 into serial data by a serial transmission driver 110 and transmits the serial data.
[0066]
The serial transmission driver 110 transmits digital data as a serial signal in conformity with the RS422 standard, for example, and can perform transmission using a small number of signal lines. In the RS422 standard, transmission is performed by a differential balanced interconnection circuit having a DC offset, and a twisted pair is used as a signal line. Thereby, noise resistance can be improved and transmission over a longer distance can be performed. In order to convert the parallel data, which is the output of the analog / digital converter 106, into serial data, it may be converted into a character format using, for example, UART (Universal Asynchronous Receiver Transmitter). In the motor driver 80, the supplied signal may be received by a receiver compliant with the serial transmission standard, converted into a binary level by an appropriate decoding circuit, and then supplied to the motor control circuit 86.
[0067]
For example, the serial transmission driver 110 may be inserted after the comparator 60 in FIG. 5 and transmit a binary level signal supplied from the comparator 60. In this case, since parallel / serial conversion of data or the like is unnecessary, the signal can be transmitted at high speed.
[0068]
The scanner motor and the control method thereof according to the present invention are not limited to the above-described embodiments, and it is needless to say that various configurations can be adopted without departing from the gist of the present invention.
[0069]
【The invention's effect】
As described above, according to the scanner motor and the control method thereof according to the present invention, the drive signal for controlling the rotation speed is transmitted from the separate drive circuit, and the scanner motor for rotating the polygon mirror by the drive signal and In the control method, the effect of reducing the influence of noise and reliably transmitting the FG signal to the controller can be achieved.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a scanner motor according to an embodiment.
FIG. 2 is a sectional view of a scanner motor according to the present embodiment.
FIG. 3 is a perspective view showing a frequency power generation magnet and a coil substrate.
FIG. 4 is a plan view of a coil substrate.
FIG. 5 is a schematic block diagram of circuits of a scanner motor and a motor driver according to the present embodiment.
FIG. 6 is a rear view of the coil substrate.
FIG. 7A is a block diagram showing a first modification of the amplifier, FIG. 7B is a block diagram showing a second modification of the amplifier, and FIG. 7C is a third modification of the amplifier. It is a block diagram which shows an example.
8A is a waveform diagram of an FG signal generated by the scanner motor according to the present embodiment, a comparator output signal, a noise mixed signal, and a control signal in the motor driver, and FIG. 8B is a conventional waveform diagram; FIG. 6 is a waveform diagram of an FG signal generated by the scanner motor, noise, a signal mixed with noise, and a control signal in the motor driver.
[Explanation of symbols]
10 ... Scanner motor 14 ... Coil substrate
16 ... Harness 18 ... Connector
22 ... rotating part 24 ... stator yoke
26 ... Insulator 30 ... Coil
32. Frequency generator coil
34, 100, 104, 108 ... Amplifier 38 ... Rotor yoke
40 ... Magnet 42 ... Frequency generator magnet
44, 46 ... Bearing 52 ... Polygon mirror
58 ... Low-pass filter 60 ... Comparator
80 ... motor driver 84 ... buffer
86 ... Motor control circuit 88 ... Clock
90 ... Power supply circuit 102 ... Amplifier
106 ... Analog / digital converter 110 ... Serial transmission driver

Claims (9)

In a scanner motor that transmits a drive signal for controlling the rotation speed from a separate drive circuit and rotates the polygon mirror by the drive signal,
A frequency generating coil for generating an FG signal according to the rotational speed of the polygon mirror;
A signal processor for performing signal processing for increasing an S / N ratio when transmitting the FG signal;
Have
A scanner motor, wherein a signal processed by the signal processor is transmitted to the drive circuit as a feedback signal of a rotational speed. The scanner motor according to claim 1,
The scanner motor, wherein the signal processor is an amplifier. The scanner motor according to claim 2, wherein
A scanner motor, wherein the amplifier amplifies and digitizes the FG signal. The scanner motor according to claim 2, wherein
The amplifier amplifies the FG signal and converts it to a binary level. The scanner motor according to claim 4, wherein
The amplifier has a binary level of the FG signal by a comparator and transmits the signal to the drive circuit by an open collector output. The scanner motor according to any one of claims 1 to 5,
The frequency power generation coil is set in an annular shape around the rotation axis,
The scanner motor according to claim 1, wherein the signal processor is disposed on an outer peripheral side of an electromotive force generation portion of the frequency power generation coil. In the scanner motor according to any one of claims 1 to 6,
The scanner motor, wherein the frequency power generation coil and the signal processor are disposed on the same substrate. In the scanner motor of any one of Claims 1-7,
A scanner motor, wherein the rotation speed of the polygon mirror is 300 [rpm] or more and 10000 [rpm] or less. In a method for controlling a scanner motor in which a drive signal for controlling the rotation speed is transmitted from a separate drive circuit and the polygon mirror is rotated by the drive signal.
Generating an FG signal corresponding to the rotational speed of the polygon mirror by a frequency power generation coil;
Performing signal processing to increase the S / N ratio when transmitting the FG signal by a signal processor;
Transmitting the signal processed by the signal processor to the drive circuit as a rotation speed feedback signal;
A method for controlling a scanner motor, comprising:

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