JP2530118B2 - Magnetic recording / reproducing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic recording / reproducing apparatus such as a video tape recorder (hereinafter referred to as VTR), and more particularly to a method for detecting a rotation speed and a rotation phase of a spindle motor.

[Conventional technology]

FIG. 8 is a view showing a conventional structure of a magnetic recording / reproducing apparatus, for example, a rotary head drum of a VTR, 31 is a rotating upper drum, 32 is a lower drum, 33 is a video head which rotates integrally with the upper drum, and 34 is an upper drum. A rotor magnet of a motor for rotating the motor, and a stator core 35 of the motor. 36 is a double-sided printed circuit board on which the circuit pattern for driving the motor and the comb-shaped pattern of the frequency generator for detecting the rotation speed of the motor are printed by etching. FIG. 9 is a view showing the side of the printed board on which the comb-shaped pattern is printed. In the figure, 38 is a comb-shaped pattern of the frequency generator.

Further, 37 in FIG. 8 is a magnet for the frequency generator which is arranged so as to face the above-mentioned printed circuit board, and its details are shown in FIG. As shown in the figure, this magnet has N-
Several S pole pairs are magnetized (for example, 48 poles). Further, the number of comb teeth of the comb tooth pattern 38 on the printed circuit board is usually the same as the number of magnetized magnetic poles of the above-mentioned magnet, or one odd number (for example, 1/3). When the rotor of the motor rotates, this frequency generator magnet also rotates facing the printed circuit board, and an induced voltage of a frequency proportional to the rotation speed of the motor is generated between the output terminals 39 and 40 on the printed circuit board. . For example, the comb pattern is 48
When the number of rotations of the pole and motor is 30 rpm, an induced voltage of 720 Hz is generated. In this way, by detecting the rotation speed of the motor and adjusting the drive voltage applied to the motor,
The rotation speed of the motor, that is, the rotation speed of the rotating drum can be maintained at a desired value.

Further, as a method for detecting the rotation speed, in addition to the method using a comb-shaped pattern and a magnet printed on such a printed circuit board, a method using an optical encoder, a method using a magnetoresistive element, etc. are considered. There is.

Further, as is well known, in VTR, in order to maintain the compatibility of recording and reproduction, it is necessary to match the phase of the video head and the signal pattern recorded on the video tape. In FIG.
41 is a magnet piece arranged to detect the mechanical position of the video head, and 42 is a coil arranged for the same purpose. Every time the rotating drum rotates once, the magnet piece passes over the coil, and the pulse signal indicating the mechanical position of the video head can be taken out. Further, as in Japanese Patent Laid-Open No. 57-100650, a rotary head drum having a structure in which a light emitting element and a light receiving element are used to detect the rotational phase of a video head is also considered.

[Problems to be solved by the invention]

However, in the above-mentioned conventional technique, since the means for detecting the rotation speed of the rotary drum and the means for detecting the rotation phase of the video head are separately configured, the number of parts increases,
It has problems such as complication of structure, and it is difficult to assemble and manage because it is necessary to guarantee the assembly accuracy of each part. Further, in particular, it is difficult to reduce the size and weight of the rotary head drum in order to secure a space for arranging an element for detecting the phase of the video head. Further, since such an element is expensive, it causes a cost increase. This prevents the VTR device from becoming smaller, lighter, and cheaper.

Therefore, the present invention solves such a problem,
The purpose is to enable accurate detection of rotation speed and rotation phase with a simple structure, reduce the number of parts of the rotary head drum, and improve its assemblability. An object is to provide a low cost rotary head drum.

[Means for solving problems]

The present invention has a magnet that is magnetized in multiple poles and that rotates with the rotation of a motor, and a rotation speed detection signal generation pattern that generates a rotation speed detection signal that detects the rotation speed of the motor; A magnetic recording / reproducing apparatus in which a printed circuit board on which a rotation phase detection signal generation pattern for generating a rotation phase detection signal indicating a rotation phase of the motor is formed for each rotation is provided facing the magnet. The rotation speed detection signal generation pattern includes two comb-shaped patterns, each comb-shaped pattern is arranged in an arc shape, and the end of the first comb-shaped pattern and the second comb-shaped pattern are arranged. The ends of the pattern are opposed to each other, and only one substantially C-shaped pattern is formed on the inner peripheral side of the comb-shaped pattern, and one end and the front of the first comb-shaped pattern are formed. One end of the substantially C-shaped pattern is connected, one end of the second comb-shaped pattern and the other end of the substantially C-shaped pattern are connected, and the rotational phase detection signal generation pattern Is formed on the outer peripheral side of one of the comb-shaped patterns, is arranged in a recess of the comb-shaped pattern, and is electrically connected to the rotational speed detection signal generation pattern. .

[Action]

According to the above configuration of the present invention, when the motor rotates,
The magnetic flux interlinking the rotational speed detection pattern and the rotational phase detection pattern formed by etching in the same process on the printed circuit board changes, and the voltage for rotational speed detection and the rotational phase detection are detected by the principle of electromagnetic induction. The voltages for are simultaneously induced.

〔Example〕

FIG. 1 is an assembly sectional view of a rotary head drum in an embodiment of the present invention, in which 1 is a rotary upper drum, 2 is a fixed lower drum, 3 is a video head, 4 is a spindle, 5 is a rotary disk, 6, 7 is a pair of ball bearings. Also, 8 and 9 are a pair of rotary transformers for transmitting and receiving signals to and from the video head, and 10
Is a preload spring and 11 is a preload boss. Further, 12 is a rotor magnet of the motor, 13 is a rotor yoke, 14 is a stator core, 15 is a coil wound around the stator core, and 16 is a stator base for fixing the stator core. Also, 17
Is a double-sided printed circuit board, a circuit pattern for driving the motor is formed on one side (upper surface) by etching, and the rotation speed of the motor, that is, the rotation speed of the rotating upper drum is detected on the other surface (lower surface). A comb-shaped pattern for moving and a comb-shaped pattern for detecting the rotational phase of the video head are formed on the same surface by etching in the same process.

FIG. 2 is a view showing the printed circuit board 17, showing the side on which the above-mentioned comb-shaped pattern is formed. Reference numeral 20 is a rotation speed detection comb-shaped pattern (hereinafter referred to as FG pattern) which is a rotation speed detection signal generation pattern, and 21 is a rotation phase detection comb-shaped pattern (hereinafter referred to as a PG pattern) which is a rotation phase detection signal generation pattern. Call). As can be seen from the figure, the PG pattern 21 is formed on the outer peripheral side of the FG pattern 20. A part of the FG pattern 20 is cut out, and the PG pattern 21 is arranged in the recess. Also,
The pitch of the PG pattern is half that of the FG pattern. Further, 22 is a terminal (hereinafter referred to as FG terminal) for taking out a voltage (hereinafter referred to as FG signal) induced in the FG pattern, and 24 is taken out as a voltage (hereinafter referred to as PG signal) induced in the PG pattern. Terminal (hereinafter called PG terminal)
Is.

Further, the FG pattern is composed of two comb-shaped patterns 20a and 20b, and a substantially C-shaped pattern 20c is formed on the inner peripheral side of the comb-shaped patterns 20a and 20b. One end of the comb-shaped pattern 20a is connected to one end of the substantially C-shaped pattern 20c, and one end of the comb-shaped pattern 20b is connected to the other end of the substantially C-shaped pattern 20c. In this way, by providing a C-shaped pattern inside the FG pattern and connecting this to the FG pattern, it is possible to eliminate the influence of the magnetic flux generated inside the C-shaped pattern. . That is, since the noise component due to the magnetic flux generated inside the C-shaped pattern can be eliminated, the FG signal can be accurately detected. Moreover, since the PG pattern 21 is electrically connected to the FG pattern, the C-shaped pattern 21c is
The noise component is also eliminated from this PG pattern, and the PG signal can also be detected with high accuracy.

In FIG. 1, reference numeral 18 denotes a plurality of lead wires for applying a motor drive voltage, taking out FG and PG signals, and the like. 19 is for FG pattern and PG pattern respectively
A magnet for inducing the FG signal and the PG signal, which is attached to the upper end surfaces of the rotor magnet 12 and the rotor yoke 13 and integrally rotates.

FIG. 3 is a diagram showing the magnet 19. This magnet 19 is magnetized with dozens of poles (for example, 48 poles),
This is the same as the number of comb teeth in the FG pattern or an integral multiple thereof. Reference numeral 25 is a first magnetic pole portion, which is an N-S pole pair showing magnetization for generating an FG signal, and a second magnetic pole portion of which a two-pole pair is further divided into two for generating a PG signal. N
Forming the S pole pair 26;

When the motor rotates, the magnet 19 rotates to face the FG pattern and the PG pattern. Then, the signals shown in FIG. 4 are detected from the FG terminal 22 and the PG terminal 24. 27 in the figure
With the FG signal, the frequency is proportional to the rotation speed of the motor.
In this way, the rotational speed of the rotary drum can be known, and the rotational speed of the rotary drum can be maintained at a desired value by adjusting the drive voltage applied to the motor. 28 is PG
This is a signal, and the PG signal is induced only when the PG magnetizing 26 passes over the PG pattern 21. That is, one pulse-shaped signal is obtained for one rotation of the upper drum, and the rotation phase of the video head can be detected by this. According to the configuration of the present embodiment, since the PG pattern and the FG pattern are formed on the same printed circuit board, it is not necessary to separately provide an element for detecting the video head rotation phase as in the conventional case, and the number of parts is reduced. Can be reduced. Moreover, since the PG pattern is formed in the cutout portion of the FG pattern, the area of the printed circuit board does not increase. In this way, the rotary head drum can be made smaller, lighter, and less expensive.

In addition, the FG pattern, PG pattern, and C-shaped pattern are formed on the same substrate by etching in the same process, so accuracy is good, and accuracy control in assembly is only required at the mounting part of the printed circuit board. It will be reduced.

Furthermore, a C-shaped pattern is provided and this is used as an FG pattern.
By electrically connecting both to the PG pattern, it is possible to eliminate the noise component due to the influence of the magnetic flux generated inside the PG pattern, and it is possible to accurately detect both the FG signal and the PG signal. In particular, since the PG signal is a smaller signal than the FG signal, the effect of improving the detection accuracy by suppressing this noise component is great.

FIG. 5 shows another embodiment of the present invention, in which the PG pattern 29 is displaced by 1/2 pitch clockwise as compared with 21 of FIG.
The PG signal at this time is 30 in FIG. That is, the generation timing (phase) of the PG signal with respect to the FG signal is different from that in the case of FIG. The shifting of the pitch is performed according to the specifications of the video head rotation phase control circuit system, but in this case also, the same effect as that of the previous embodiment can be obtained. Further, the same effect can be obtained by shifting not only the 1/2 pitch but also the 1/2 × n (n is an integer) pitch, which is beyond the scope of the present invention.

Further, FIG. 7 shows another embodiment of the present invention, in which the magnetizing pattern shown in FIG.
The function of 19 and the function of the rotor magnet 12 are combined. With this configuration, in addition to the effects similar to those of the previous embodiment, the number of parts can be further reduced.

Although the VTR rotary head drum has been described in detail in the present embodiment, the present invention is not limited to this and can be applied to a magnetic recording / reproducing device such as a floppy disk device.

〔The invention's effect〕

As described above, according to the present invention, the rotation speed detection signal generation pattern for generating the rotation speed detection signal for detecting the rotation speed of the motor and the rotation phase detection signal indicating the rotation phase of the motor for each rotation of the motor. The printed circuit board on which the rotational phase detection signal generation pattern that generates
A magnetic recording / reproducing device provided opposite to the magnet, wherein the rotation speed detection signal generation pattern includes two comb-shaped patterns, and the comb-shaped patterns are arranged in an arc shape. And an end of the second comb-shaped pattern of the second comb-shaped pattern is opposed to each other, and only one substantially C-shaped pattern is formed on the inner peripheral side of the comb-shaped pattern. One end of the first comb-shaped pattern and one end of the substantially C-shaped pattern are connected, and one end of the second comb-shaped pattern and the other end of the substantially C-shaped pattern are connected. And the rotation phase detection signal generation pattern is formed on the outer peripheral side of one of the comb tooth-shaped patterns, and is arranged in the recess of the comb tooth-shaped pattern, and the rotation speed detection signal generation pattern is formed. Pattern and electric Since the motors are rotationally connected to each other, the rotational speed detection and the rotational phase detection of the motor can be performed by the same component. Therefore, the number of components can be reduced and the cost can be reduced as compared with the conventional magnetic recording / reproducing apparatus. Become. Further, in designing, it is not necessary to consider the space for disposing the phase detection dedicated component as in the conventional case, and the device can be made smaller and lighter. In addition, since the rotation speed detection signal generation pattern, the rotation phase detection signal generation pattern, and the substantially C-shaped pattern are all formed on the same substrate in the same etching process, the accuracy of the patterns is good, and the conventional pattern can be obtained. It is not necessary to separately manage the assembly precision of each part. Moreover, it is possible to eliminate noise components during rotation speed detection and rotation phase detection with a simple structure that is easy to assemble, and it is possible to detect the rotation speed detection signal and the rotation phase detection signal with high accuracy. As described above, the practical effects of the present invention are great.

[Brief description of drawings]

FIG. 1 is an assembled sectional view of a rotary head drum showing an embodiment of the present invention. FIG. 2 is a diagram showing a printed circuit board which constitutes an embodiment of the present invention. FIG. 3 is a diagram showing a magnet which constitutes an embodiment of the present invention. FIG. 4 is an output signal waveform diagram according to an embodiment of the present invention. FIG. 5 is a view showing a printed circuit board which constitutes another embodiment of the present invention. FIG. 6 is an output signal waveform diagram according to another embodiment of the present invention. FIG. 7 is an assembled sectional view of a rotary head drum showing another embodiment of the present invention. FIG. 8 is an assembled sectional view showing a conventional rotary head drum. FIG. 9 is a diagram showing a printed circuit board constituting a conventional example. FIG. 10 is a diagram showing a magnet constituting a conventional example. 1 …… Rotating upper drum 2 …… Lower drum 3 …… Video head 17 …… Printed circuit board 20 …… FG pattern 21 …… PG pattern

 ─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-58-117459 (JP, A) JP-A-58-117460 (JP, A) JP-A-58-118055 (JP, A) Actual publication Sho-51- 17887 (JP, Y2) Actual public Sho 51-22680 (JP, Y2)

Claims (1)

(57) [Claims] 1. A rotation speed detection signal generation pattern for generating a rotation speed detection signal for detecting a rotation speed of the motor, the motor having a magnet which is magnetized in multiple poles and which rotates with the rotation of the motor. A printed circuit board on which a rotation phase detection signal generation pattern for generating a rotation phase detection signal indicating the rotation phase of the motor is formed for each rotation of The rotation speed detection signal generation pattern includes two comb-shaped patterns, each of the comb-shaped patterns is arranged in an arc shape, and the end of the first comb-shaped pattern and the second comb-shaped pattern are arranged. End portions of the comb-shaped pattern are opposed to each other, and only one substantially C-shaped pattern is formed on the inner peripheral side of the comb-shaped pattern. And one end of the substantially C-shaped pattern are connected, one end of the second comb-shaped pattern and the other end of the substantially C-shaped pattern are connected, and the rotational phase detection signal The generation pattern is formed on the outer peripheral side of one of the comb-shaped patterns, is arranged in the recess of the one comb-shaped pattern, and is electrically connected to the rotation speed detection signal generation pattern. And a magnetic recording / reproducing apparatus.