JPH07140411A - Fine rotation driving device - Google Patents

Abstract

PURPOSE:To provide a fine rotation driving device which enables the rotation direction and rotation position of a rotor to finely be adjusted with the input signal of a driving circuit. CONSTITUTION:The rotation driving device, which is equipped with the driving circuit and rotates a motor, having magnets on its rotor and a driving coil and a sensor detecting the positions of the magnetic poles of the magnets at its fixed part, for ward and backward by controlling a current supplied to the driving coil according to the output of the sensor and also changing the direction of the current supplied to the driving coil according to the logical value of the input signal inputted to the driving circuit, is provided with a rectangular wave oscillator having a variable resistor 1 which adjusts a duty ratio continuously; and its output signal is inputted as the input signal of the driving circuit and the duty ratio of the output signal is adjusted by the variable resistor 1 to adjust the rotation position of the rotor of the motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a minute rotation driving device which can be used for optical adjustment of a polygon scanner incorporating a rotary polygon mirror driving motor used in an image scanning device such as a laser printer. is there.

[0002]

2. Description of the Related Art FIG. 4 is a schematic sectional view of a polygon scanner body. As shown in the figure, the rotor 44, which is a rotating portion, is rotatably supported by a radial bearing 42 and thrust bearings 41, 43 fixed to a fixed shaft 54. A rotary mirror 45 (generally a polyhedron) having a mirror surface 45a on its side surface is attached to the rotatably supported rotor 44 by being sandwiched between two upper and lower mirror support members 46. A magnet 47 for generating a rotational torque is fixed to the mirror support member 46 further below.

On the other hand, on the base 55, a plurality of coils 48a, 48b, 48c for generating a rotational torque on the surface facing the magnet 47 and a plurality of hall elements for detecting the magnetic pole position of the magnet 47. 49a, 49
b and 49c are arranged, and a yoke 50 of a magnetic material is provided to form a magnetic path of the magnet 47. The fixed portion facing the opposite side of the magnet 47 is provided with a rotary mirror 4 by a suction force acting between the magnet 47 and the yoke 50.
A magnet 51 is provided to reduce the distortion of No. 5.
These polygon scanner bodies are protected by a protective case 52 provided with a dustproof glass 53 window.

The main body of the polygon scanner has a rotating magnet 47, stationary coils 48a to 48c, and a horn.
The rotary elements 45a to 49c constitute a motor for driving the rotary mirror 45 and are driven by the drive circuit of the polygon scanner shown in FIG. 3 (details will be described later). Normally, when scanning laser light, the rotating mirror 45 is rotated at a high speed, and the dustproof glass 53 is rotated.
Although not shown in the figure, the reflected light that has entered the laser light through and has been reflected by the mirror surface 45a scans the photosensitive drum and the like through an optical system including a lens and the like.

Here, the optical system including this lens needs to be finely adjusted individually in order to optimize the laser light state at each scanning position. To make this adjustment, it is necessary to align the rotary mirror 45 with an appropriate position, but for this adjustment, the adjuster removes the protective case 52 and turns the rotary mirror 45 by hand. ing.

[0006]

However, in recent years, the rotational speed of the rotary mirror 45 has been increased, and as the bearings (the radial bearing 42 and the thrust bearing 41), the one using the air dynamic pressure bearing is beginning to be used. However, this bearing extremely dislikes dust and the like, and as the rotating mirror 45 becomes faster, it is more likely to be damaged by dust. Therefore, when making the above adjustment, it is necessary to use a clean room or the like, and it must be handled very carefully. Further, since the number of steps for touching the rotating mirror 45 by hand increases, there is a problem that the work is troublesome and the mirror surface 45a is scratched.

For this reason, there is also a method of covering the rotating mirror 45 with a protective case 52 and performing adjustment without touching the rotating mirror 45 directly with the hand. There was a problem that adjustment would be very difficult.

The present invention has been made in view of the above-mentioned problems, and when the above problems are eliminated and, for example, when it is used in a rotary polygon mirror drive motor of a polygon scanner, it is possible to remove the protective cover of the rotary mirror without removing it. It is an object of the present invention to provide a minute rotation drive device capable of adjusting the rotation direction and minute rotation position of a rotation mirror according to an input signal of a drive circuit.

[0009]

In order to solve the above problems, the present invention comprises a drive circuit, in which a magnet is arranged in a rotor, a drive coil is arranged in a fixed portion, and a sensor for detecting the position of a magnetic pole of the magnet is arranged. The motor configured as described above controls the current flowing through the driving coil by the output of the sensor, and changes the direction of the current flowing through the driving coil by the logical value of the input signal input to the driving circuit to rotate the motor forward. In a rotation driving device of a motor for reversing / reversing, a rectangular wave oscillator having adjusting means for steplessly adjusting a duty ratio is provided, and an output signal thereof is inputted as an input signal of a driving circuit, and the adjusting means By adjusting the duty ratio of the output signal,
It is characterized in that the rotational position of the rotor of the rotor is adjusted.

Further, an inverter for inverting the phase is provided in the output circuit of the rectangular wave oscillator, and a forward / reverse changeover switch for switching the output of the rectangular wave oscillator and the output of the inverter and inputting them to the drive circuit is provided. ON of the forward / reverse changeover switch
It is characterized in that the motor is controlled in the forward / reverse rotation and the driving is stopped by the / OFF operation.

Further, the motor is a rotary polygon mirror scanning motor in which a rotary polygon mirror is attached to a rotor.

Further, the rotor of the rotary polygon mirror scanning motor is supported by a dynamic pressure bearing.

[0013]

According to the present invention, by adopting the above configuration, the drive circuit normally / reverses the motor according to the value of the logical input signal, so that the positive rotation speed of the motor is from 5% to 5%.
It gets slower as it gets closer to 0%, stops at 50%, 50
When it becomes less than or equal to%, reverse rotation occurs, and as it approaches 0%, the reverse rotation speed increases. Therefore, the rotation position of the rotor of the motor can be finely adjusted by adjusting the duty ratio of the rectangular wave input signal input to the drive circuit.

[0014]

【Example】

[Embodiment 1] An embodiment of the present invention will be described in detail below with reference to the drawings. In this embodiment, the polygon scanner main body having the configuration shown in FIG. 4 is used as the rotating body that employs the minute rotation driving device. The structure and operation of the polygon scanner body are as described above. Normally, when scanning the laser light, the rotating mirror 45 is rotated at a high speed, the laser light is incident through the dustproof glass 53, and the reflected light reflected by the mirror surface 45a is omitted in the figure. Scans the photosensitive drum and the like through an optical system including a lens and the like.

FIG. 3 is a diagram showing the configuration of a drive circuit of the polygon scanner. In the polygon scanner main body, as shown in FIG. 4, a motor 24 is composed of a magnet 47 of a rotating part, coils 48a to 48c and hall elements 49a to 49c provided on a base 55, and a driving circuit of this polygon scanner. Driven by.

As shown in FIG. 3, the drive circuit of the motor 24 has drive elements 25a to 25c and 26a for controlling the drive current.
To 26c, the drive elements 25a to 25c, 26a to 26c
Control element 21, power supply 27, power switch 28 for controlling
And resistors 29 and 30.

A wheel for detecting the magnetic pole position of the magnet 47
The outputs of the loop elements 49a, 49b, 49c are input to the control element 21. An input signal having a logic level of "0" or "1" is input to the input terminal 22 of the control element 21, and when the input signal is "0", the magnet 47 (rotor 44) is driven to rotate normally. 25a to 25c, 26a to 26c
To control the drive elements 25a to 25c and 26a to 26c so as to rotate the magnet 47 (rotor 44) in the reverse direction when the input signal is "1". Apply current. Normally, a continuous signal of logic level "0" or "1" is input to the input terminal 22 to rotate the rotation mirror 45 at high speed.

At the time of adjustment, a continuous rectangular wave signal having a logic level "0" or "1" is input from the input terminal 22 of the control element 21 as shown in the figure, and the duty ratio is changed to change the motor. The torque of 24 can be controlled to control the rotation speed and the forward / reverse rotation. The minute rotation drive apparatus of the present invention changes the duty ratio of the continuous rectangular wave signal having the logic level "0" or "1" input to the input terminal 22 to change the magnet 47 (rotor 44) minutely. It is to rotate.

FIG. 1 is a diagram showing a configuration of an oscillation circuit of a minute rotation driving device of the present invention. As shown in the figure, this oscillation circuit includes a variable resistor 1, diodes 2a and 2b, a resistor 3a,
3b, resistors 4 and 7, inverters 6a, 6b and 6c, and an output terminal 8. This output terminal is connected to the input terminal 22 of the control element 21 of FIG.

This oscillator circuit outputs a rectangular wave signal from the output terminal 8 by repeatedly charging and discharging the capacitor 5. The pulse width of logic level '1' of the output signal is resistor 3
a and the resistance value of the 1a portion of the variable resistor 1 and the resistance value of the resistor 4 and the time constant of the capacitor 5, the pulse width of the logic level "0" is 3b and 1b of the variable resistor 1.
It is determined by the sum of the resistance value of the part and the resistance value of the resistor 4 and the time constant of the capacitor 5. Therefore, the output signal can be adjusted steplessly by adjusting the variable resistor 1 and changing the ratio between the resistance value 1a and the resistance value 1b, and the torque of the motor 24 can be adjusted by this output signal. Control the
The rotation speed (including stop) and normal / reverse rotation can be controlled. Therefore, when the motor is a rotary polygon mirror scanning motor that drives the rotary mirror 45 having the configuration shown in FIG. 4, the rotary mirror can be finely rotated without removing the protective case 52.

[Embodiment 2] FIG. 2 is a diagram showing an oscillating circuit of a minute rotation drive apparatus according to Embodiment 2 of the present invention. This circuit has an inverter 10 and a switch 11 at the output of the circuit shown in FIG.
a, 11b and power switch 28 (see FIG. 3) turned on /
An OR circuit 12 that outputs a signal for turning OFF is added. Power switch 28 when switch 11a is pressed
Is turned on, a normal rotation signal is output from the output terminal 8, and the motor 24 rotates in the normal direction according to the duty ratio determined by the resistance value 1a and the resistance value 1b of the variable resistor 1. When the switch 11b is pressed, the power switch 28 is turned on and the reverse rotation signal is output to the output terminal 8
Similarly, the motor 24 reversely rotates according to the duty ratio determined by the resistance value 1a and the resistance value 1b of the variable resistor 1. As a result, the rotation direction can be switched with one touch, and the rotation mirror 45 can be arbitrarily rotated and stopped.

In the above embodiment, an example in which the minute rotation driving device is used for minute rotation driving of the rotary polygon mirror driving motor of the polygon scanner has been described, but the present invention is not limited to this and the driving circuit is not limited to this. And a motor having a configuration in which a magnet is provided in the rotor, a drive coil is provided in the fixed portion, and a sensor for detecting the position of the magnetic pole of the magnet is arranged, while controlling the current flowing through the drive coil by the output of the sensor, The present invention can be widely used for a rotation driving device of a motor that changes the direction of a current flowing through the driving coil according to the logical value of an input signal input to the driving circuit to perform normal / reverse rotation.

[0023]

As described above in detail, according to the present invention, the rotor rotational position can be adjusted by adjusting the duty ratio of the logic input signal of the drive circuit.
For example, if it is applied to a minute rotation drive of a rotary polygon mirror drive motor of a polygon scanner, the protection case can be removed without removing the protective case.
It is possible to obtain an excellent effect that the rotational position of the rotary polygon mirror can be finely adjusted. Therefore, there is no damage to the rotary mirror, no invasion of dust, no need to work in the clean room, and the efficiency of adjustment work can be greatly improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an oscillation circuit of a minute rotation drive device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an oscillation circuit of a minute rotation drive device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a drive circuit of a polygon scanner.

FIG. 4 is a cross-sectional view showing a schematic configuration of a polygon scanner main body.

[Explanation of symbols]

 1 Variable Resistor 2a Diode 2b Diode 3a Resistor 3b Resistor 4 Resistor 5 Capacitor 6a Inverter 6b Inverter 6c Inverter 7 Resistor 8 Output Terminal 9 Output Terminal 10 Inverter 11a Switch 11b switch 12 OR circuit 21 control element 22 input terminal 24 motor 25a drive element 25b drive element 25c drive element 26a drive element 26b drive element 26c drive element 27 power supply 28 power supply switch 29 resistor 30 resistor

Claims (4)

[Claims] 1. A motor having a drive circuit, wherein a rotor is provided with a magnet, a fixed portion is provided with a drive coil, and a sensor for detecting the position of the magnetic pole of the magnet is arranged to drive the motor by the output of the sensor. In a rotary drive device for a motor, which controls the current flowing through the coil, and changes the direction of the current flowing through the driving coil according to the logical value of an input signal input to the driving circuit to perform forward / reverse rotation, A rectangular wave oscillator having adjusting means for steplessly adjusting the duty ratio is provided, the output signal of which is input as an input signal of the drive circuit, and the adjusting means adjusts the duty ratio of the output signal. A minute rotation drive device characterized by adjusting the rotation position of a motor rotor. 2. An output circuit of the rectangular wave oscillator is provided with an inverter for inverting the phase, and a forward / reverse changeover switch for switching the output of the rectangular wave oscillator and the output of the inverter to input them to the drive circuit is provided. ON of the forward / reverse changeover switch
2. The micro rotation drive device according to claim 1, wherein the motor is controlled to rotate in the normal / reverse direction and stopped by a turning-off operation. 3. The minute rotation drive device according to claim 1, wherein the motor is a rotary polygon mirror scanning motor having a rotor to which a rotary polygon mirror is attached. 4. The micro rotation drive device according to claim 3, wherein a rotor of the rotary polygon mirror scanning motor is supported by a dynamic pressure bearing.