JPH07123676A - Frequency generator - Google Patents

Abstract

PURPOSE:To make it difficult to produce an open circuit caused by etching at the corner of the folded part of a pattern. CONSTITUTION:Among repeated square-wave shaped n-fold (wherein (n) denotes an integer not smaller than 2) frequency generation patterns, circumferential direction patterns 41P and 42P do not contribute to the generation and radial direction patterns 41R and 42R contribute to the generation. The widths wp of the patterns 41P and 42P are larger than the widths wr of the patterns 41R and 42R. Therefore, an open circuit in the pattern which is caused by uneven etching, etc., when the patterns are made by etching is hardly produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency generator suitable for application to, for example, a spindle motor used in a floppy disk drive or the like.

[0002]

2. Description of the Related Art In a spindle motor used in an optical disk drive such as a floppy disk drive, in order to control the rotation speed of the spindle motor,
Servo control is used.

In this servo control, it is necessary to detect the number of revolutions of the spindle motor to create a speed detection signal. Usually, the speed is generated by a frequency generator coaxially mounted on the rotation shaft of the spindle motor. A detection signal is generated.

It is desirable that the frequency generator for the optical disk drive be thin, and therefore, a pattern for detecting the number of revolutions (speed), in other words, a pattern for frequency power generation is formed on the printed wiring board. Has become.

FIG. 2 shows the structure of a motor 20 in which a pattern 12 for frequency power generation according to a conventional technique (Japanese Utility Model Publication No. 61-81780) is formed on a printed wiring board 1.

In FIG. 2, a stator core 3 is attached to the center of a printed wiring board 1 via a support base 2. A stator winding 4 is attached to the stator core 3.

Further, the printed wiring board 1 has a circular hole formed in the axial center thereof as viewed from the stator core 3, through which the housing 6 is inserted, and the shaft 8 through the bearing 7. It is rotatably supported.

Further, a cylindrical rotor 9 having a flange portion is attached to the shaft 8. Inside the rotor 9, a driving magnet 10 is arranged in the circumferential direction,
A frequency power generation magnet 11 as a speed detection magnet magnetized in multiple poles is arranged on the flange portion.

FIG. 3 shows the structure in which the drive magnet 10 and the frequency power generation magnet 11 are attached to the rotor 9, that is, the structure of the mover 21.

FIG. 4 shows a plan configuration of a printed wiring board 1 having a frequency power generation pattern 12 formed at a position facing the frequency power generation magnet 11.

This frequency power generation pattern 12 is a pattern of repetitive square wave frequency power generation patterns connected in series and formed in a circumferential shape, and is connected to other parts 13 and 14.
have.

The connecting portions 13 and 14 are connected through terminals 15 and 16 to a speed detecting amplifier 17 (see FIG. 2) composed of transistors, resistors and the like.

5 and 6 are partial cross sections of a frequency power generation magnet 11 as a speed detection magnet provided on the flange portion of the rotor 9 and a frequency power generation pattern 12 formed on the printed wiring board 1, respectively. The structure and the plane structure are shown.

As can be seen from FIGS. 5 and 6, the frequency power generating magnet 11 and the frequency power generating pattern 12 form one square wave pattern for each pole (magnetic pole N or magnetic pole S) of the magnet. Due to the rotation of the rotor 9, the magnetic poles N, S
Magnetic flux φ formed by and the frequency power generation pattern 12
And are interlinked. In this case, assuming that the total number of the square wave patterns is n and the voltage generated in one square wave pattern is e, the AC voltage output E1 shown in Expression 1 is generated between the terminals 15 and 16 in FIG. .

[0015]

[Equation 1] E1 = e × n

FIG. 7 shows the waveform of the AC voltage output E1. That is, the central angle per pole of the magnet is θ1
(See also FIG. 6)
A substantially sinusoidal AC voltage output E1 corresponding to the rotation of the rotor 9 is generated between the two terminals 15 and 16.

In FIG. 8, the AC voltage output E1 is supplied, the AC voltage output E1 is amplified, and then compared with a constant threshold value to output an unbalanced repetitive square wave voltage output E0 to the terminal 18. The configuration of a circuit having a speed detection (FG: frequency generator) amplifier 17 is shown. This square wave voltage output E0 is used for speed servo control.

In the case where the application as shown in FIG. 8 is considered, the higher the amplitude level of the AC voltage output E1 is, the electrical design of the signal processing circuit after the speed detection amplifier 17 to which the AC voltage output E1 is supplied. It is easy and power consumption can be reduced. Further, the larger the signal amplitude level of the AC voltage output E1, the better the S / N.

The above-mentioned Japanese Utility Model Laid-Open No. 61-81780 discloses a technique for increasing the signal amplitude level of the AC voltage output E1 obtained from the frequency power generation pattern 12.

FIG. 9 shows a configuration example of a frequency power generation pattern 12A according to the technique. In this FIG.
A frequency power generation pattern 12A having a so-called double structure having an outer pattern 21 and an inner pattern 22 is formed on the printed wiring board 1A provided with the cutouts B. In addition, in the following description, it is also referred to as frequency power generation patterns 21 and 22. Further, the printed wiring board 1A is provided with a notch B, but this is provided for the purpose of downsizing the printed wiring board 1A. Even in such a case, the dual frequency power generation patterns 21 and 22 are provided so that the same signal amplitude level can be obtained.

The frequency power generation patterns 21 and 22 are connected in series through the interconnection part 23, and the connection parts 13A and 14 are connected.
An AC voltage output E3 for speed detection is generated between terminals 15A and 16A connected to A.

FIG. 10 shows the frequency power generation patterns 21 and 2.
2 shows a relationship between a part of 2 and the frequency power generating magnet 11 shown in FIG. 3, and it can be seen that two square wave patterns are formed for one magnetic pole.

Here, m square wave patterns are formed in the circumferential direction, and when the induced voltage per pole is e, both ends of the frequency power generation patterns 19 and 20 are respectively formed.
AC voltage outputs E31 and E32 shown in equations 2 and 3 are generated.

[0024]

[Equation 2] E31 = e × m

[0025]

[Equation 3] E32 = e × m

Therefore, an AC voltage output (hereinafter, also referred to as a combined AC voltage output) E3 obtained by combining these terminals appears between the terminals 15A and 16A.

FIG. 11 shows these AC voltage outputs E3 and E3.
1 shows the relationship between the signal amplitude level E and the phase θ of E1, E32.

[0028]

As can be seen from FIG. 11, in order to increase the amplitude level E of the combined AC voltage output E3, the AC voltage output E31 and the AC voltage output E3 can be increased.
It is desirable that the phase difference θ2 from 2 is as small as possible.
For that purpose, it is necessary to bring the frequency power generation pattern 21 and the frequency power generation pattern 22 as close as possible.

FIG. 12 shows a partially enlarged structure of the frequency power generation pattern 21 and the frequency power generation pattern 22 which are created close to each other.

In the example of FIG. 12, the pattern width (line width) of the frequency power generation patterns 21 and 22 is wa, and the interval between them is also wa. Specifically, the pattern width wa =
It is 0.2 (mm). Further, the angle θ1 is θ1 =
It is 3 degrees.

However, as shown in FIG. 12, when the two frequency power generation patterns 21 and 22 are made close to each other, for example, a frequency power generation pattern such as a portion surrounded by a dotted circle 23 in FIG. The inventors of the present application have found a problem that, in the corner portions of the bent portions of the patterns 21 and 22, etching unevenness is likely to occur during etching and disconnection is likely to occur. Therefore, there is a limit in reducing the line width of the frequency power generation patterns 21 and 22. After all, the signal amplitude level of the AC voltage output cannot be increased so much.

The present invention has been made in consideration of the above problems, and is provided at the corners of the bent portion of the pattern.
It is an object of the present invention to provide a frequency generator capable of making it difficult for wire breakage to occur during etching.

Another object of the present invention is to provide a frequency generator capable of relatively increasing the amplitude level of the AC voltage output.

[0034]

In the present invention, for example, as shown in FIG. 1, n (n ≧ 2) -fold frequency wave power generation patterns 40 (41, 42) having repetitive waves are formed in a circumferential shape. Of the repeating square wave n-fold frequency power generation pattern 40 having the printed wiring board 1B, the pattern width wp of the patterns 41P and 42P in the circumferential direction P is set to the radial direction r.
The patterns 41R and 42R are formed thicker than the pattern width wr. The repetitive wave shape may be a repetitive square wave shape or the like.

Further, according to the present invention, the interval dr between the adjacent patterns 41R and 42R in the radial direction is made narrower than the interval dp between the adjacent patterns 41P and 42P in the circumferential direction.

Further, in the present invention, n is 2.

According to the present invention, among the n (n is an integer of 2 or more) multiple frequency power generation patterns 40 having a repetitive wave shape, for example, a repetitive square wave shape, the patterns 41P and 42P in the circumferential direction that do not contribute to the power generation. The pattern width w of the radial patterns 41R and 42R that contributes to the power generation with the pattern width wp
It is formed thicker than r. For this reason, disconnection of the pattern is less likely to occur due to etching unevenness or the like when etching the pattern at the corners of the bent portion of the pattern.

Further, according to the present invention, the interval dr between the adjacent patterns 41R and 42R in the radial direction is made narrower than the interval dp between the adjacent patterns 41P and 42P in the circumferential direction. Therefore, the amplitude of the AC output voltage can be increased.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the frequency generator of the present invention will be described below with reference to the drawings. In the drawings referred to below, the same reference numerals are given to those corresponding to those shown in FIGS. Further, the configuration other than the frequency power generation pattern is the same as those shown in FIGS. 2 to 12, and will be described with reference to these drawings in order to avoid complexity.

FIG. 1A shows an overall structure of a repetitive square wave double frequency power generation pattern 40 as a speed detection pattern formed on a printed wiring board 1B in the frequency power generator according to this embodiment. Shows. As the printed wiring board 1B, for example, a copper foil thickness of 35 (μ
Use the paper phenol substrate of m).

In FIG. 1A, pattern 4 for frequency power generation
The diameter D of 0 is about 65 (mm), and the height h of one square wave is about 5 mm.

FIG. 1B shows a partial detailed configuration of the frequency power generation pattern 40 of the example of FIG. 1A.
The frequency generator is a printed wiring board 1B having a drive magnet 10 attached to the rotor 9 shown in FIG. 3, a mover 21 having the frequency power generation magnet 11, and a frequency power generation pattern 40 shown in the example of FIG. 1A. Composed of and.

In the example of FIG. 1, double frequency power generation patterns 41 and 42 having a repetitive square wave shape connected in series are circumferentially formed on the printed wiring board 1B.

In this case, as shown in FIG. 1B, each of the frequency power generation patterns 41 and 42 has a pattern extending in the circumferential direction P (hereinafter, referred to as a circumferential pattern) 41P and 42P and a radial direction R. It can be seen that the pattern 41R and 42R (hereinafter referred to as a radial pattern) extending in the direction.

The frequency power generation patterns 41, 42
Among them, the pattern widths (line widths) wp of the circumferential patterns 41P and 42P are formed to be thicker than the pattern width wr of the radial patterns 41R and 42R. For example, specifically, the pattern width wp is set to wp = 0.3 mm, and the pattern width wr is set to wr = 0.2 mm.

In addition, adjacent radial patterns 41R,
The pattern spacing dr of 42R is made narrower than the pattern spacing dp of the adjacent patterns 41R and 42R in the circumferential direction. Specifically, dr = 0.2 mm, dp = 0.3 mm
I have to.

As described above, according to the example of FIG. 1, among the double frequency power generation patterns 41 and 42 having the repeating square wave shape,
A pattern in the circumferential direction that does not contribute to power generation (a pattern parallel to the moving direction of the frequency generating magnet 11 of the moving element 21) 41
Radial patterns (patterns perpendicular to the moving direction of the frequency power-generating magnet 11 of the moving element 21) 41R and 42R that contribute to the power generation with the pattern width wp of P and 42P.
It is formed thicker than r.

For this reason, it is difficult for the pattern to break at the corner 23 (see FIG. 12) of the pattern due to uneven etching when the pattern is formed by etching.

Further, according to the example of FIG. 1, the pattern spacing dr between the adjacent radial patterns 41R and 42R is made narrower than the pattern spacing dp between the adjacent circumferential patterns 41R and 42R. For this reason, it becomes possible to keep the distance dp between the radial patterns 41R and 42 contributing to power generation close to each other, the phase difference θ2 (see also FIG. 11) becomes small, and the combined AC voltage output E3 ( (See FIG. 11) can be increased, and the disconnection of the pattern is less likely to occur during etching. The pattern spacing dr and the pattern spacing dp may be the same, for example, dr = dp = 0.2 mm.

Further, since the pattern widths wp of the circumferential patterns 41P and 42P that do not contribute to power generation are made relatively thick, the DC resistance component of the frequency power generation pattern 40 as a whole is small, and the DC resistance component thereof is small. Since it is possible to reduce the voltage drop (loss) due to, the effect that the combined AC voltage output E3 generated between the terminals 16A and 16B connected to the connection portions 13B and 14B can be increased is also obtained from this point. To be

Furthermore, as a result, the amplitude level of the combined AC voltage output E3 can be increased, so that the signal processing of the speed detection amplifier 17 (see FIG. 8) and thereafter to which the combined AC voltage output E3 is supplied. The electrical design of the circuit is easy and the power consumption can be reduced. Further, the larger the signal amplitude level of the combined AC voltage output E3, the better the S / N. As a result, the derivative effect that the speed (rotation) unevenness of the motor whose speed is controlled by the frequency generator having the configuration of FIG. 1 can be reduced is obtained.

In the example shown in FIG. 1, two square wave patterns are formed for one magnetic pole as shown in FIG. 10, but the number of patterns may be three or more. Good. The shape of the pattern is not limited to the square wave shape, and may be a trapezoidal wave shape, a triangular wave shape, or any wave shape.

Further, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various configurations can be adopted without departing from the gist of the present invention.

[0053]

As described above, according to the present invention, n (n) having a repetitive wave shape, for example, a repetitive square wave shape is used.
Is an integer greater than or equal to 2), the pattern width of the circumferential direction pattern that does not contribute to power generation is made thicker than the pattern width of the radial direction pattern that contributes to power generation. Therefore, it is possible to achieve the effect that the disconnection of the pattern, which is caused by the uneven etching when the pattern is etched, is unlikely to occur.

Further, according to the present invention, the interval between adjacent patterns in the circumferential direction is made narrower than the interval between adjacent patterns in the radial direction. Therefore, the effect that the amplitude of the AC output voltage can be increased is achieved.

[Brief description of drawings]

FIG. 1A is a plan view showing an overall configuration of an example of a frequency power generation pattern that constitutes a frequency generator according to this embodiment. FIG. 1B is an enlarged view showing a part of the configuration of the frequency power generation pattern of the example of FIG. 1A.

FIG. 2 is a cross-sectional view showing the configuration of a motor incorporating a frequency generator.

FIG. 3 is a perspective view showing a configuration of a mover that constitutes a frequency generator.

FIG. 4 is a plan view showing a configuration of a printed wiring board on which a frequency power generation pattern according to a conventional technique is formed.

FIG. 5 is a partial cross-sectional view showing a relative positional relationship between a frequency power generation magnet provided on a flange portion of a rotor and a frequency power generation pattern formed on a printed wiring board.

FIG. 6 is a partial plan view substantially corresponding to FIG.

FIG. 7 is a waveform diagram showing a waveform of an AC voltage output obtained from the frequency generator shown in FIG. 2 (FIG. 5).

FIG. 8 is a block diagram showing a configuration of a circuit having a speed detection amplifier which is supplied with an AC voltage output and outputs an unbalanced repetitive square wave voltage output.

FIG. 9 is a plan view showing a planar configuration of a printed wiring board on which a frequency generation pattern of generally double repeated square waves is formed.

FIG. 10 is a plan view showing a correspondence relationship between a double repetitive square wave frequency power generation pattern and a rotating magnet.

11 is a waveform diagram showing a waveform of an AC voltage output generated by the frequency generator of FIG.

FIG. 12 is an enlarged view showing a partial configuration of a frequency power generation pattern according to a conventional technique.

[Explanation of symbols]

 40, 41, 42 Frequency power generation patterns 41P, 42P Circumferential patterns 41R, 42R Radial patterns dr Intervals between adjacent radial patterns dp Intervals between adjacent circumferential patterns wp Circular directions Pattern width of pattern wr Pattern width of pattern in radial direction

Claims (4)

[Claims] 1. A printed wiring board having a repetitive wavy n (n ≧ 2) -fold frequency power generation pattern formed in a circle, wherein the repetitive wavy n-fold frequency power generation pattern has a circular shape. A frequency generator characterized in that a pattern width of a circumferential pattern is formed thicker than a pattern width of a radial pattern. 2. The frequency generator according to claim 1, wherein the interval between the adjacent patterns in the radial direction is made narrower than the interval between the adjacent patterns in the circumferential direction. 3. The frequency generator according to claim 1, wherein the repetitive wave shape is a repetitive square wave shape. 4. The frequency generator according to claim 1, wherein the n is 2.