JPH0946995A - Frequency generators and motors - Google Patents

Abstract

A pattern integration type frequency generator is used as a speed detector of a motor driven at a low speed. A frequency generator (FG) includes a printed circuit board (1) that is integrally formed with a rotor of a motor and rotatably supports a multi-pole magnetized annular magnet. A rectangular FG pattern 2 is formed in a loop on the surface of the printed board 1. Further, on the surface of the printed board 1, an FG pattern 3 is formed around the FG pattern 2 in a loop shape, and the rectangular portion is arranged so as to shift the electrical phase by about 90 degrees from the FG pattern 2. There is. Furthermore, on the surface of this printed circuit board 1,
One end of each of the loop-shaped FG patterns 2 and 3 is connected, and a signal generation circuit 4 is provided for pulsing the electric signals generated from the respective FG patterns 2 and taking the exclusive OR of each other and outputting them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency generator and a motor for driving a drum of a printer, for example.

[0002]

2. Description of the Related Art Conventionally, in order to accurately control the speed of a motor, it is important to improve the accuracy of motor rotation speed detection by a frequency generator (hereinafter referred to as FG).

For example, in a brushless motor, etc.,
A pattern integration type FG is used as a velocity detector.

As shown in FIG. 5, a conventional pattern integration type FG has a rotating magnet 51 in which S poles and N poles are alternately magnetized in multiple poles and a magnetized surface of the magnet 51. The details formed in a loop shape on the fixed FG substrate 52 are composed of a rectangular detection pattern 53.

Usually, the FG is integrally provided on a printed circuit board of a motor together with an armature coil, a position detecting element, a motor driving coil and the like. For example, the magnet 51 is provided integrally with a rotor rotatably supported by a housing (not shown), and the detection pattern 53 is formed on the printed circuit board side which is the stator.

In the case of this FG, each time the rotor of the motor makes one revolution, a signal having a frequency of 1/2 of the number of poles of the magnet 51 is generated. The motor detects the speed based on the frequency of this signal and controls the rotation of the rotor (speed control). For example, if the number of poles of the rotor is 1000, a signal having an amplitude of 500 times can be obtained as an output signal of the FG during one rotation of the rotor.

When this type of motor is used for driving a drum of a copying machine, for example, the drum of the copying machine usually operates at a lower speed than the rotation of the motor. I am biting.

However, biting the gear in this way is not efficient because of the problem of gear noise and the complication of the copying machine.

Therefore, it is conceivable to directly drive the drum by the motor, that is, to rotate the motor at a low speed from the beginning, but since the FG is used as a speed detector of the motor, the rotation speed of the motor is further reduced. If you let
The output value of the FG signal (FG output) and the frequency become low,
The so-called uneven rotation, which reduces the rotation accuracy of the motor, increases.

In order to increase the frequency (amplitude number) of the FG output by rotating the motor at low speed, the magnetizing interval of the magnet 51 is narrowed to increase the magnetizing number, or the detection pattern 53 facing the magnet 51 has a rectangular shape. The spacing may be narrowed further, but the number of magnetized magnets 51 may be further increased,
At present, there is a technical limit to miniaturize the detection pattern 52. Even if the fine processing is possible, the FG output (electromotive force) generated by the rotation of the rotor becomes small, and it becomes difficult to use it as a speed detector of the motor.

Japanese Unexamined Patent Publication No. 4-69036 discloses a technique for increasing the FG output in a pattern integration type motor FG. In this case, as shown in FIG. 6, a plurality of layers of detection patterns 62 and 63 are laminated corresponding to the magnetized surface of the magnet 61 to form an FG, and as shown in FIG. FG output Eab having a high peak value by simply adding the electromotive force waveforms Ea and Eb generated in the detection patterns 62 and 63 of FIG.
Trying to get.

[0012]

However, in the case of such an FG for a motor, although the FG output can be increased, the frequency of the FG output obtained with respect to the rotation of the rotor cannot be increased, and as a result, low speed driving is achieved. However, there is a problem that the rotation accuracy of the motor cannot be satisfactorily obtained even if it is used for a motor.

The present invention has been made in order to solve such a problem, and a frequency generator which can obtain a good rotation accuracy of a motor even when the motor is driven at a low speed and can be used as a speed detector of the motor. And to provide a motor.

[0014]

In order to achieve the above-mentioned object, the invention according to claim 1 is a multi-pole magnetized rotating magnet having an annular magnetizing surface, and a magnetic influence of the rotating magnet. And a first detection pattern for generating an electric signal, and an electric signal which is affected by the magnetic effect of the rotating magnet and is out of phase with the phase of the electric signal generated by the first detection pattern by about 90 degrees. It is provided with a second detection pattern and a signal generation circuit for pulsing the electric signals generated in the first detection pattern and the second detection pattern and taking the exclusive OR of each other and outputting the exclusive OR.

Therefore, even when the motor is driven at a low speed, a high frequency and high output FG output is generated, and good rotation accuracy of the motor can be obtained.

According to a second aspect of the invention, in the frequency generator of the first aspect, the first detection pattern,
It is characterized in that it is arranged in parallel with the second detection pattern.

According to the second aspect of the invention, both patterns can be arranged equidistant from the rotary magnet.

Further, the invention according to claim 3 is the frequency generator according to claim 1, wherein the first detection pattern and the second detection pattern are laminated via an insulating layer. I am trying.

According to the third aspect of the invention, the total area of the detection patterns formed on the printed circuit board is small, and the size of the board can be reduced.

The invention according to claim 4 is the frequency generator according to claim 3, characterized in that the insulating layer contains a magnetic material such as ferrite.

According to the fourth aspect of the present invention, the insulating layer containing the magnetic material can generate an electric signal equivalent to the upper detection pattern near the rotary magnet in the lower detection pattern.

Further, the invention according to claim 5 is the frequency generator according to claim 1, wherein in the frequency generator according to claim 1, an insulating plate is provided between the first detection pattern and the second detection pattern. It is characterized in that it is formed on the front and back surfaces respectively.

According to the fifth aspect of the present invention, the total area of the detection patterns formed on the printed circuit board can be small, and the board can be miniaturized.

According to a sixth aspect of the present invention, in the frequency generator according to the fifth aspect, the insulating plate is formed by forming an insulating film on the front and back surfaces of a plate material containing a metal as a main component. There is.

According to the sixth aspect of the present invention, the plate material containing metal as a main component can generate an electric signal equivalent to the detection pattern on the front surface of the substrate on the detection pattern on the back surface.

Further, a motor according to a seventh aspect of the present invention includes the frequency generator according to the first to sixth aspects.

According to the seventh aspect of the invention, since the high frequency FG output is obtained from the frequency generator, the speed detection accuracy is improved and the motor can be driven at low speed without uneven rotation.

As a result, it is possible to reduce the number of gears that have conventionally been bitten by the motor, solve the problem of gear noise, and simplify the structure of the copying machine.

As described above, the frequency generator can be used as a speed detector for a motor that drives at a low speed.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a frequency generator (hereinafter referred to as FG) which is one embodiment according to the present invention, and FIG. 2 is a plan view showing detection patterns 2 and 3 of the FG of FIG. is there. In the figure, 1 is a printed circuit board of the motor.
This printed circuit board 1 is formed by forming insulating coatings on the front and back surfaces of a plate material containing metal as a main component. Examples of the metal here include iron and silicon steel. On the surface of the printed circuit board 1, a first detection pattern 2 having an FG rectangular shape (hereinafter, referred to as FG pattern 2) is formed in a loop shape. Also, on the surface of this printed circuit board 1, FG
A second detection pattern 3 (hereinafter referred to as FG pattern 3) is formed so as to be adjacent to the pattern 2 and to shift the phase of the rectangular portion of the FG pattern 2 into an electrical angle by about 90 degrees around the pattern 2. There is. The FG pattern 3 and the FG pattern 2 are electrically insulated. Further, a signal generation circuit 4 connected to one end of each loop-shaped FG pattern 2, 3 is provided on the surface of the printed board 1. The signal generation circuit 4 includes a waveform shaping circuit 5 for pulsing an electric signal (electromotive force) generated in each of the FG patterns 2 and 3, and an exclusive OR of each pulse signal waveform-shaped by the waveform shaping circuit 5. And a logic circuit 6 for outputting this as an FG signal to a speed control circuit of a motor (not shown) or the like. This logic circuit 6
Is an exclusive OR circuit (X-OR circuit), for example, and outputs the FG signal only when the pulse waveforms of the signals generated in the FG patterns 2 and 3 have different heights.

The printed circuit board 1 is provided with the FG patterns 2 and 3, the signal generating circuit 4, and other parts of the motor, such as an amateur coil, a position detecting element, and a motor driving coil. The rotor of the motor is rotatably provided on the printed circuit board 1 in the same manner as the conventional one so as to face the FG pattern 2 of the printed circuit board 1 at a predetermined interval, and this rotor has a donut-shaped magnet (rotary magnet). ) 7 are integrally provided with the same number of magnetic poles as the conventional one.

Next, the operation of this FG will be described with reference to FIG.

In this FG, when the rotor of the motor rotates, the magnet 7 and the FG pattern 2 generate an A-phase electric signal (basic signal) of a predetermined frequency, which is input to the signal generation circuit 4. Further, the magnet 7 and the FG pattern 3 generate a B-phase electric signal having the same frequency as the A-phase electric signal and a phase difference of 90 degrees, and input to the signal generation circuit 4. In this signal generation circuit 4, each input electric signal is waveform-generated by the waveform shaping circuit 4a and is pulsed.

For example, the electric signal of the A phase is a pulse signal 31 of a predetermined frequency as shown in FIG. 11A, and the electric signal of the B phase is of the A phase as shown in FIG. The pulse signal 32 has a phase that is substantially 90 degrees out of phase with the pulse signal.

The pulse signals 31 and 32 are exclusive ORed by the logic circuit 6, and the signals are output only when the input pulse signals have different waveforms. Therefore, FIG. As a result, a pulse waveform (FG signal) 33 having a frequency twice that of the basic signal is obtained as a result. The FG signal 33 corresponds to the pulse signals 31 and 3 described above.
Since it is based on 2, its output value (peak value) is
It has the same level as the pulse signals 31 and 32.

As described above, according to this FG, the phases of the FG patterns 2 and 3 are approximately 9 as the rotor rotates.
Electric signals that are 0 degrees apart are generated, and these are generated by the signal generation circuit 4
Is pulsed, exclusive-ORed, and output as the FG signal 33, so that the frequency is twice the frequency of the generation source (basic signal) and the output value (peak value)
It is possible to obtain the FG signal 33 that does not decrease.

The FG signal 33 obtained by this FG is
Since it is twice as large as the conventional FG signal (the number of amplitudes is 1/2 of the number of poles), a signal having the same number of amplitudes as the number of poles per rotor rotation can be obtained as a result.

As a result, the speed of the motor driven at a low speed can be accurately detected, and this FG can be used as a speed detector.

As a result, it is possible to inexpensively realize a motor with less uneven rotation even when it is driven at a low speed. By driving this motor at a low speed, the drum of the copying machine can be directly driven without passing through the gear, and the structure of the gear and the like can be deleted from the copying machine, which reduces the cost and noise of the copying machine itself. Can also contribute.

The present invention is not limited to the above embodiment.

In the above embodiment, the two FG patterns 2 and 3 are arranged side by side only on the surface of the printed circuit board 1, but as shown in FIG. 4, A is formed on the printed circuit board such as a thin glass epoxy board. B-phase FG pattern 3 in which a FG pattern 2 of a phase is formed, and a rectangular shape is formed on the back surface of the printed board 1 so as to face the FG pattern 2 and to shift the phase from the FG pattern 2 by an electrical angle of approximately 90 degrees. (Dotted line in the figure) may be provided. In this case, an equivalent current can be generated in each detection pattern on the front and back surfaces of the printed circuit board. Further, the total area of the detection patterns formed on the printed circuit board is small, and the board can be downsized.

A layer of the FG pattern 2 is formed on the surface of the printed circuit board 1, and an insulating layer containing a magnetic material such as ferrite is interposed on the layer to shift the phase from the FG pattern 2 by about 90 degrees in electrical angle. The FG pattern 3 having a rectangular shape may be formed. In this case, the same current can be generated in the two detection patterns stacked on the printed board via the insulating layer. Moreover, the total area of the detection pattern formed on the printed circuit board is small,
The substrate can be miniaturized.

Further, in the above embodiment, the X-OR circuit is used to double the frequency of the basic signal. However, an exclusive OR circuit is simply formed by combining electronic parts such as an AND gate and an OR gate. It may be configured by software or software. Further, by further increasing the number of detection patterns 2 and 3, the frequency of the obtained FG signal can be further increased.

[0045]

As described above, according to the present invention, the first detection pattern formed in the loop shape is adjacent to or laminated to the first detection pattern so that the phase of the generated electric signal is shifted by approximately 90 degrees. The second detection pattern is formed in a shape, and the electric signals generated mutually are pulsed to obtain an exclusive OR, and an FG signal having a frequency twice that of the electric signal (basic signal) is obtained. The speed can be accurately detected even when driven at a low speed, and the frequency generator can be used as a speed detector for the motor.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an FG according to an embodiment of the present invention.

FIG. 2 is a plan view showing an FG detection pattern of FIG.

FIG. 3A is a diagram showing a pulse waveform of A phase in this FG. (B) is a figure which shows the pulse waveform of B phase in this FG. (C) shows phase A and B in this FG
The figure which shows the pulse waveform obtained by carrying out the logic synthesis of each pulse waveform of a phase.

FIG. 4 is a diagram showing another embodiment of the present invention.

FIG. 5 is a diagram schematically showing the structure of a conventional FG.

FIG. 6 is a diagram showing a conventional multi-layered FG.

7 is a diagram showing an FG signal obtained by the FG of FIG.

[Explanation of Codes] 1 ... Printed board, 2, 3 ... FG pattern, 4 ... Signal generating circuit, 5 ... Waveform shaping circuit, 6 ... Logic circuit, 7 ... Magnet.

Claims (7)

[Claims] 1. A multi-pole magnetized rotating magnet having an annular magnetizing surface; a first detection pattern for generating an electric signal by the magnetic influence of the rotating magnet; and a magnetic influence of the rotating magnet. And a second detection pattern for generating an electric signal having a phase shifted by about 90 degrees from the phase of the electric signal generated by the first detection pattern; and the first detection pattern and the second detection pattern. A frequency generator comprising: a signal generation circuit that converts each generated electric signal into a pulse and outputs the exclusive OR of the electric signals. 2. The frequency generator according to claim 1, wherein the first detection pattern and the second detection pattern are arranged in parallel. 3. The frequency generator according to claim 1, wherein the first detection pattern and the second detection pattern are laminated via an insulating layer. 4. The frequency generator according to claim 3, wherein the insulating layer contains a magnetic material. 5. The frequency generator according to claim 1, wherein the first detection pattern and the second detection pattern are formed on the front and back surfaces of an insulating plate, respectively. . 6. The frequency generator according to claim 5, wherein the insulating plate is a plate material having a metal as a main component and insulating coatings formed on the front and back surfaces thereof. 7. A motor comprising the frequency generator according to claim 1.