JPS59191123A - Cylinder motor for vtr - Google Patents

Abstract

PURPOSE:To realize a miniaturized and light-weight cylinder motor which can be manufactured easily, is low in cost, and has a structure suitable for mass- production, by installing a section for generating the magnetic field of the signal (tack signal) for detecting the position of a video head to the inside or marginal area of the center hole of the rotor magnet of the cylinder motor. CONSTITUTION:The cylinder motor of this invention has a structure, in which a flat type 3-phase DC brushless motor is directly connected to the lower part of the bottom cylinder and its rotor magnet is positioned at the lowest part under a condition where its magnetic pole is oriented downward and a stator faces to the rotor magnet. Above and below the central part of the bottom cylinder 9 two bearings 6 and 6' are installed, by which a rotary shaft 7 is supported under a freely rotary condition. According to experiences obtained with this cylinder motor, the magnetic field at the magnetic pole surface of the rotor magnet 4 is detected by magnetic field detecting elements 1 and 1' and an electric current made to flow to a stator coil 10 is controlled in accordance with the output signal of the elements 1 and 1' by an electronic circuit. The rotor magnet 4 is driven by the electric current flowing to the stator coil 10.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a cylinder motor for rotating the video head of a VTR, and is particularly suitable for a VTR that is small, lightweight, and low in cost.
This relates to cylinder motors.

[Background of the invention]

FIG. 1 shows an example of the structure of a conventional cylinder motor, FIG. 1(α) is a longitudinal sectional view of the overall structure, and FIG. 1(h) is a plan view of the motor stator section. This example has a structure in which a 6-phase flat brushless DC motor is built into the lower cylinder.

In the figure, the rotor magnet 4 has a multipolar magnetic pole whose plane is magnetized equally divided into fan shapes.

The back side magnetic poles of this multi-pole magnetic pole are short-circuited by a rotor yoke 8 made of a magnetic material such as iron, while the front side magnetic poles are directed upward. A rotor magnet consisting of such magnetic poles and rotor yoke 8) 4&'! .

It is attached to the rotating shaft 7 via the rotor boss 5. The rotor boss 5 is press-fitted or bonded to the rotating shaft 7. Rolling bearings are used for the two bearings 6.6r that support the rotating shaft 7, and these are provided at the upper and lower portions of the lower cylinder 9.

The motor stator includes a flat annular stator yoke 6 fixed to the upper peripheral edge of the side wall of the lower cylinder 9, and a stator coil 10 stacked and fixed on the stator yoke 3. The stator coil 10 has an eight-pole structure in which the number of coil poles per coil is equal to that of the rotor magnet 4. The stator coils 10 are arranged above the rotor magnet 4 and facing the magnetic poles of the rotor magnet 4.

On the outer periphery of the stator coil 10, three magnetic field detecting elements i, 1', 1' as single position detection sensors are fixed together with the wiring board 2 at predetermined angular intervals (300). The magnetic field detection elements 1, 1, 1, . . . detect the leakage magnetic field in the side direction of the rotor magnet 4, and detect the rotational position thereof. A Hall element is commonly used as a magnetic field detection element. The wiring board 2 is the lower cylinder 9
It is provided in a notch part of a part of the side wall of the built-in part of the motor so as to protrude outward. The inner surface of the side wall is magnetic.

A shield link 11 made of a solid material is fitted.

The secondary winding 16 of the rotary transformer is fixed to the upper surface of the stator.

A flywheel 17 is attached to the rotating shaft 7 at the bottom of the lower cylinder 9.
Fixed. Two tack magnets (18, 18') are attached to the flywheel 17 with opposite polarities. Tack magnets 18 and 18' are respectively fixed at corresponding positions to video heads 14 and 14'. One magnetic field detection element 19 is fixed to the lower side surface of the lower cylinder 9. The fixed position is at the upper part of the circumference through which the tack magnets 18, 18' rotate.

In a cylinder motor with such a configuration, magnetic

The magnetic pole position signals of the rotor magnets 4 detected by the field detection elements 1, 1, 1, . As a result, the rotor magnet 4 is rotationally driven, and the upper cylinder 12 is rotated at a predetermined number of rotations. Upper cylinder 12
The video head 14, which is attached to this by rotation of the video head 14.
14' is this.

A videotape (not shown) runs next to it.

Scan the surface. The video signals on the tape are therefore recorded and played back by the video heads 14, 14'.

Tack magnet 18.18' on flywheel 17
The magnetic field detection element 19 constitutes a position detection section of the video heads 14 and 14'. The magnetic field detection element 19 identifies the video head 14.14 and simultaneously generates a pair of positive and negative tack signals for controlling its rotational phase. The rotational speed of the upper cylinder 12 is controlled by using a voltage generated in a frequency signal generating coil incorporated in the stator/coil 10 as a speed signal.

This is done by controlling the motor input.

However, the cylinder motor having such a conventional structure has the following various drawbacks.

(1) The magnetic field detection elements i, i', i'' are provided at the outer peripheral edge of the stator coil 10 and are configured to detect the position using the side magnetic field of the rotor magnet 4.

Therefore, it is constant from the rotor magnet 4.

It is necessary to generate side leakage that exceeds the amount.

As a result, magnetic noise around the motor increases and motor efficiency decreases.

(2) Since the wiring board 2 is provided on the side surface of the stator coil 10, the dimensions of the motor become large.

(3) In the case of a structure in which 3 magnetic materials such as ferrite are used in the magnetic field detection elements 1, 1', 1, etc., cogging torque (reluctance torque) is generated between the magnetic flux of the rotor magnet and uneven rotation occurs. This causes an increase in

(4) Since the tack detection section is also attached externally to the cylinder, the cylinder size tends to increase (and magnetic noise due to the tack magnet magnetic field is likely to occur), and the tack detection section is also attached to the cylinder.

It is a separate piece from the head, and the dog from the video head.

Because it is far away, it is relative to the video head position.

This makes positioning the tack detection part difficult.

[Purpose of the invention]

An object of the present invention is to eliminate the drawbacks of the above-mentioned prior art and to provide a cylinder motor having a mass-produced structure that is easy to manufacture, low cost, small and lightweight. The cylinder motor of the invention has a structure in which the magnetic field generating section for the position detection signal (column difference signal) of the il+ video head is provided within the three center holes of the rotor magnet or at the periphery thereof.

(2) Let r be the distance between the center of the flat rotor magnet and the front coordination amount detection signal magnetic field generating section.

When doing so, at least a sensor for detecting the rotational position of the rotor magnet is placed on the plane of the stator yoke.

within the section and the distance τ from the center of the stator yoke.

It is located at a point near the distance.

[Embodiments of the invention]

The present invention will be explained below based on examples.

FIG. 2 shows a first implementation of the cylinder motor of the present invention.

An example vertical cross-sectional view, FIG. 6 (α), shows the same cylinder motor.

FIG. 3B shows a plan view of the magnetic poles of the rotor magnet, and FIG. 3B shows a plan view of the stator yoke.

This cylinder motor has a structure in which a flat three-phase DC brushless motor is directly connected to the bottom of the lower cylinder, with the rotor magnet pole facing downward and the stator and child facing it at the bottom. Two shaft/receivers 6, 6t are provided above and below the center of the lower cylinder 9, and the rotary shaft 7 is rotatably supported by these.

A disk 16 is fixed to the top of the upper bearing 6 on the rotating shaft 7. An upper cylinder 12 is fixed to the disk 13. Two video heads 14 and 14' are fixed to the side surface of the upper cylinder 12.

There is.

A rotor is provided at the bottom of the lower bearing 6' on the rotating shaft 7.

The yoke 8 is fixed, and the rotor yoke 8vC is mo.

- The rotor magnet 4 of the rotor has its magnetic pole face facing downward.

It is fixed and fixed. The lower side of the rotor magnet 1°4 is opposite to the magnetic pole face of the rotor magnet.

A motor stator is fixed to the opposite side. The mo.

Evening stator coil 10, stator yoke 3, magnetic field detection.

It consists of an element 1.1', 1'' and a wiring board 26.

A wiring pattern conductor is provided on the wiring board 26, and further includes terminals of the stator coil 10, terminals of the magnetic field/detection elements 1, 1., 1'', and an IC/21 of the drive electronic circuit.
and other electronic components 22 are wired in a thin shape.

The wiring board 26 is fixed to the back side of the stator yoke B (the surface opposite to the stator coil 10).

The magnetic field detection elements 1, 1., 1.' are inserted and fixed into small holes provided in the plane of the peripheral edge of the center hole of the stator yoke B. The tip end surface of the magnetic field detection element 1.1'1'' faces the magnetic pole surface of the rotor magnet 4, and the rotational position can be detected by the magnetic field directly below the magnetic pole surface.

It has become. The terminal of the magnetic field detection element 1.1!1" is fixed.

It is pulled out to the back side of the electronic yoke 3 and is on the board 26 surface.

connected to. At the outer periphery of stator yoke B.

The inner bottom part of the cup-shaped shield case 11 is hard.

has been established. Shield case 11 is the lower cylinder.

It is fixed to the lower cylinder 9 at the lower side of the cylinder 9.

Ru.

The circumference of the center hole of the flat annular rotor magnet 4.

A minute magnet (tack magnet) 18 for detecting the position of the video head is fixed at a position along the line that forms a predetermined angle with the video head 14, 14'. This embodiment has a configuration in which the magnetic field detection element 1 is used to obtain rotational position signals (tack signals) of the video heads 14, 14'. Therefore, the installation radius of the cod magnet 18 is selected at a position where the magnetic field detection element 1 can detect the magnetic field signal.

According to this embodiment with such a structure, the magnetic field detection/output sensor 1
．． 1' and 1t', the magnetic pole surface output field of the rotor magnet 4 is detected, and the electric current applied to the stator coil 10 by the electronic circuit 10 is controlled in accordance with this output signal.

Ru. The rotor magnet 4 is rotationally driven by the current flowing through the stator coil 10. The upper cylinder 12 is rotated by 40 rotations of the rotation/child magnet, and the video head, which is fixed thereto, is rotated by 120 rotations of the upper cylinder.

It will be done.

In the configuration of this embodiment, a tack magnet magnetic field is used.

The polarity of is the same as the polarity of the rotor magnet magnetic field.

Because of this, the magnetic field detection elements 1, 1, 1, etc. roar.

The force voltage has a waveform in which the tack signal voltage is superimposed on the position signal voltage.

Figure 3 (α) is a plan view of the magnetic poles of the rotor/magnet 4 of the cylinder motor in Figure 2, and (6) is the stator yaw 6.
FIG. 2C shows a cross-sectional view taken along a line passing through the center of the stator yoke 6 and the center of the magnetic field detection element 1.

The rotor magnet 4 has a flat annular structure in which the plane is magnetized equally into eight poles in a fan shape, and a tack magnet 18 is fixed to the periphery/portion of the center hole. Fixed 10 stator yoke 6 (・
It has a flat concave portion (seat gable portion) 40 in the center, and small through holes are provided in this portion at 120 degree intervals.

The magnetic field detection elements 1.1', 1'' are inserted and fixed here.The sensing parts of the magnetic field detection elements 1.1', 1... From the plane of part 40,
It protrudes on the rotor magnet 4 side.

I'm being forced to come out. In this example, magnetic field detection elements 1, 1-1r
r can detect both the magnetic field of the rotor magnet 4 and the magnetic field of the tack magnet 18 at the same radial position.

It is installed in a position where

The concave (spot facing) structure of the stator yoke 3 concentrates the magnetic flux of the rotor magnet 4 on the outer plane part with a larger radius than the spot facing part 40 of the stator yoke 3, and prevents the counter-bore of the stator coil 10 provided here. Improve power value and improve motor efficiency. At the same time, the magnetic fluxes of the rotor magnet 4 and the tack magnet 18 are concentrated on the magnetic field detection elements i, i', 1' to increase their output values. Therefore, high quality position detection signals and tack signals can be obtained. Furthermore, the structure in which the magnetic field detecting elements are inserted into the holes of the stator yoke can improve the alignment accuracy of the magnetic field detecting elements and simplify the structure of the stator. By using a soft magnetic material with high specific resistance, such as soft ferrite, for the stator yoke 6, a motor with less core loss and higher efficiency can be constructed, and a concave portion (recessed portion) in the center can be easily formed. .

Figure 4 shows the stator yoke 3 with an outer diameter of approximately 38771771 mm and the outer diameter.

Using a rotor magnet 4 with a diameter of about 36 mrrL and an inner diameter of about 12 mm, the magnetic field detection element 1 is set to the installation position of the magnetic field detection elements 1.1', 1' and the depth of the recess (spot facing part) in the center of the stator yoke 6. ．． j′, 1” output and stator coil 1
FIG. 3 is a schematic diagram showing the result of performing an actual test with a back electromotive voltage value of 0.

The figure (a) shows the tack magnet 18 and magnetic field detection element 1.
．． Magnetic field detection element 1 with respect to radial distance X from 1'1''.
Position detection signal voltage of 1., 1.. (output by 8 main magnetic poles of rotor magnet) V// and tack signal voltage ■
The characteristics of T are shown. It can be seen from the figure that as X increases, vH increases, but V7' decreases. ! +1.5 mm is the optimal value that can increase both VH and VT.

FIG. 2B shows the magnetic field detection elements 1.1' and 1'' relative to the depth Z of the recessed portion (spot facing portion) 40 of the stator yoke 3.

Position detection signal voltage Vll, tack signal voltage ■T and fixed.

The characteristics of the back electromotive force value of the electronic coil 10 are shown. Concave.

The part (spot facing) has a deep depth Z outside the root electronic yoke.

Magnetic flux concentration on the circumferential plane and magnetic field detection element 1.1', 1''.

The value is high and each value can be increased. VH8■T
Depth 7. Increased by about 2-6% per Ojmm, E.

increases by about 0.1%. Note that Eo is mixed with VH and VT on the vertical axis E. This is because the scale of VT and V# are different.

FIG. 5 is an example of a driving system for the cylinder motor shown in FIG. 2. The magnetic field detection elements 1, 1, and i II generate output voltages corresponding to the magnetic field distribution in which the magnetic field of the rotor magnet 4 and the magnetic field of the tank magnet 18 are superimposed.The respective outputs are amplified by amplifiers 30.50' and 30''. After that, it is input to the energization signal forming circuit 67. Then, the drive circuit 3
Create a pulse that activates 8. The drive circuit 38 operates the stator coil 10 of the motor according to the output pulse of the energization signal forming circuit #537.

It supplies current from a power source and provides rotational driving force to the rotor of the motor.

Since this example has a configuration in which the tack signal is extracted from the output of the magnetic field detection element 1, the amplified signal of the magnetic field detection element 1 is also input to the signal processing electronic circuit. The signal processing electronic circuit is a comparator 619 phase adjustment.

Circuit 32. It is composed of a pulse forming circuit 66 and a phase comparison circuit 64. In this signal processing electronic circuit, each circuit separates a voltage signal caused by the magnetic field of the tack magnet 18, delays it, forms a pulse, and compares its phase with a reference signal 36 from a reference signal generator 35. And the obtained phase error signal is the motor drive'q? I) input to circuit 38;

In the pulse forming circuit 33, a logic circuit forms pulse signals corresponding to the positions of the two video heads 14, 14. The drive circuit 38 controls the input to the motor coil 10 and controls the rotational phase of the motor so as to make the phase error signal zero.

FIG. 6 shows the fifth step in the process of separating the tack signal from the signal detected by the magnetic field detection element 1 in the circuit of FIG. 5 to form a rotational position signal of the video head 14.
It is a time chart of the signals of the main part of the figure. ■H is the voltage due to the main magnetic pole grinding field of the rotor magnet, and VT is the voltage due to the tack magnet. Further, Vnv is a magnetic field detection signal detected by the magnetic field detection element IVc.

Magnetic field detection signal amplified by amplifier 30 ■HU is comparator 6
1 and is compared with the reference voltage ■R. This separates the tack pulse P. Next phase iJ! In the circuit 32,
Tack pulse P is delayed by a predetermined amount (until the point at which the video head begins scanning the tape) and pulse P2 is output from the circuit 32.

In the pulse forming circuit 33, the falling time t1 of the pulse P2
The high frequency clock signal CP is counted by a predetermined value starting from . As a result, a phase detection signal P3 with a duty of 50 arcs is formed. Then, at time t2 when the phase detection signal P changes from high level to low level, the first video head starts scanning the magnetic tape, and at time t when the phase detection signal P changes from low level to high level, the second video head starts scanning the magnetic tape. starts one scan on the tape. With this method, duty 5
By forming a 0% phase detection signal P3, one tack magnet can be used to determine the rotational position of two video heads (
phase) can be detected.

Since this embodiment has the above-mentioned configuration, the disadvantages (1) to
The advantage is that (4) can be completely removed.

has. Note that the structure of this embodiment reduces the cogging torque because cogging torque is generally proportional to the distance between the magnetic field detecting elements 1, 1, 1'' and the rotating shaft 7.
This is because, in this embodiment, the magnetic field detecting element 1.1', i'' is located near the rotating shaft 7, and this distance is significantly smaller than that of the conventional device.

Further, according to this embodiment, in addition to the above-mentioned advantages, there are the following effects.

(α) The structure of 1 near 1 stator yoke 3 is shown in Figure 3 (1! I
), a concave portion is formed in the small diameter portion. For this reason, the rotating magnet 4 is fixed.

The distance between the convex part of the large diameter part of the electronic yoke 6 is shorter than the distance between the rotary magnet 4 and the concave part, and the magnetic resistance is small. Therefore, the magnetic flux of the rotary magnet 4 is Concentrates on the large diameter part of the motor, improving motor efficiency.

(b) Since the heads of the magnetic field detection elements 1, 1., 1.- provided in the recessed portion of the stator yoke 3 protrude as shown in FIG. The magnetic flux of the tack magnet 18 is transmitted to the magnetic field detection element 1. i'
, 1''. Therefore, position detection signals and tank signals with high S/N ratios can be obtained.

(C) Since the stator yoke 3 has the recessed portion as described above, it is light.

Therefore, a small and lightweight motor can be constructed.

(d) Since the wiring board 26 is fixed on the front surface of the fixed yoke 3, a compact cylinder motor with an integrated drive circuit can be realized.

In the above embodiment, the magnetic field detecting elements 1r, 1" are mounted at the same radial position as the magnetic field detecting element 1, but the mounting radial position of the magnetic field detecting element 1'1" is It may be different from that of the detection element. In this way, the tack signal will not be superimposed on the magnetic field detection elements 1', 1'', and the position detection accuracy of these two elements can be improved.

FIG. 7 shows the cylinder motor of the present invention.

Other structures of the foot yoke are shown. 1-0 Figure (a) shows a cross section of the rotor magnet 4 and stator yoke B, Figure (b) shows the cross section of the rotor magnet 4 and stator yoke B.
shows a plan view of the stator yoke 3. In this structure, the shape of the recess (spot facing part) in the part where the magnetic field detection elements 1, 1, 1, etc. are fixed is not annular as shown in FIG. 3(b), but the recess 4
The feature is that 0.0 is expanded only in the radial direction where the magnetic field detection elements 1.1', 1, . . . are present.

The operation and effect of this structure are similar to those of the embodiments shown in FIGS. 2 and 6. Although the present structure is such that a recess (spot facing) is provided at each small hole position side, it is also possible to have a structure in which a recess is provided only around the center of each small hole.

FIG. 8 is a diagram showing still another structure of the stator yoke 6. The figure (α) is a plan view of the stator yoke 3, and the figure (b) is a plan view of the stator yoke 3.
) is a sectional view taken along a line passing through the center and each of the magnetic field detection elements 1 and 1r.

The feature of this structure is that the magnetic field detection element fixing part has an annular groove 41.
A magnetic field detection element is fixed in this.

This is what I decided to do. In this structure as well, the above-mentioned Column 2
The same effect and effect as in the case of FIGS. 6 and 6 can be obtained.

FIG. 9 shows still another structure of the stator yoke B. Figure (α) is a plan view of the stator yoke B, and Figure (h) is a sectional view taken along a line passing through its center and each of the magnetic field detection cables 1 and 1'.

Figure 9 shows the concave part (spot facing part) in the center of the stator yoke 3.
It has a structure in which notches 40 are provided at the inner peripheral edges of 40, and magnetic field detection elements 1, 1, 1, and so on are provided in these notches. The effects of this structure are the same as those described above.

FIG. 10 shows still another structure of the stator yoke B in which the stator yoke 6 is not provided with a recessed portion (spot facing portion). In this structure, the degree of concentration of magnetic flux on the magnetic field detection element and stator yoke is low, so the output of the magnetic field detection element and the back electromotive force of the coil are reduced, but the stator yoke has a simple structure and has the advantage of being easy to manufacture. .

Figure 11 shows the tack magnet 18 and the rotor magnet 4.
This structure is provided in a notch 45 on the inner peripheral edge of the center hole. With such a structure, the magnetic field detection elements 1i', i'' can be installed at a large radius position where the amount of magnetic flux of the rotor magnet 4 is large without reducing the tack output.Therefore, it is possible to increase the position detection signal output, which is advantageous. .Additionally, tack magnet 1
Since the dimension of B can also be increased, the tack signal output can also be improved. Since there is little disturbance in the magnetic field of the rotor magnet 4 due to the magnetic field of the tack magnet on a single day, the detection accuracy is also high.

Figure 12 shows the tack magnet 18 and the rotor magnet 4.
Figure 13 shows a structure in which the tank magnet 18 is mounted on a boss structure 24 that fixes the rotor turf to the rotating shaft 7 within the center hole of the rotor magnet 4. Show the structure.

In the structure shown in FIG. 13, as a result of experiments, the boss part structure 24 is made of a magnetic material, the magnetic poles of the tack magnets 18 are set in the radial direction and have the same polarity as the magnetic poles of the rotor magnet 4, and the tip magnetic pole is the same as the magnetic pole of the rotor magnet 4. By making the structure close to the inner circumferential edge, a cylinder with a tack signal output can be created, and we have obtained results that the level can be sufficiently put to practical use.

FIG. 14 shows an example of a structure in which the tack magnet 18 is not provided separately but is integrated into the rotor magnet 4. A convex portion is provided on the inner peripheral edge of the magnetic pole of the rotor magnet 4, and this magnetic field is used as a tank signal generating magnetic field. Since this structure does not require fixing the tack magnet, it has the advantage of being low cost, having a simple structure, and being able to position the tack magnetic field with high precision.

In the embodiments shown in FIG. 2 and below, an axial air gap type flat motor has been described, but the same applies to other radial air gap type motors, which are also within the scope of the present invention.

In FIG. 15, a magnetic field detection element 1 and a tack magnet 18 are attached to a radial gap type flat motor.

- shows a cross-sectional view of an example;

In the figure, 7 is the rotating shaft, 51.52 is the bearing,
56 is a housing, 54 is a stator yoke, 55 is a coil, 56 is a rotor yoke made of Fg, etc., and 57 is a magnet.

This example also has the same effects as the example shown in FIG. 2 above.

〔Effect of the invention〕

According to the cylinder motor of the present invention, the following effects can be achieved.

+11 - between rotor magnet and stator magnet.

Since the tank magnet and the magnetic field detection system are provided on the inner peripheral side or the small diameter side, the space efficiency is better than that of the conventional type. Therefore, a small and highly efficient motor can be constructed.

(2) A recess is provided at the center periphery of the stator yoke.

Since the magnetic field detection system is installed inside this,
The magnetic field detection element output and motor efficiency can be further increased by concentrating the magnetic flux.

(3) The magnetic field generating section is provided at a small radius position within the motor electromagnetic section. Therefore, magnetic noise to the outside of the motor can be prevented.

Also, cogging torque can be significantly reduced.

(4) Since the rotor magnet rotational position detection sensor can also be used as a tack sensor, the entire cylinder motor can be made smaller and has fewer parts.

can be reduced. For this reason, it can be manufactured at low cost.

Furthermore, positioning work for the tack sensor becomes unnecessary.

(5) By fitting into a mold, one stator yoke having a hole for attaching a magnetic field detection system can be made. Therefore, the work of assembling the magnetic field detection element in the stator is easy and the precision of assembling can be increased.

(6) By improving the senna output, the detection can be improved by 41 degrees.

(7) Since the wiring board can be provided on the back surface of the stator yoke (opposite the surface on which the stator coil is identified), the wiring board can be exposed to the outside of the motor case. Therefore, a high-density mounting structure can be achieved by mounting drive circuit ICs and other components on the surface of the distribution board. It also makes it easier to maintain and inspect hilly wiring and cross circuits. Further, by eliminating the noise caused by the propagation of the rotating magnetic field to the wiring conductor, the signal quality can be improved, and highly accurate control becomes possible.

Furthermore, the wiring board 0 can have a structure that does not protrude in the radial direction, and the shield case can also be formed into a cup shape with no cutouts on the side, so that it can be made small, lightweight, and have low magnetic noise.

[Brief Description of the Drawings] Fig. 1 is a structural example of a conventional cylinder motor, Fig. 2 is an analytical view of the first embodiment of the cylinder motor of the present invention, and Fig. 3 is a diagram of the rotor magnet of the same motor. A plan view of the magnetic poles and a plan view of the stator yoke part. Figure 4 is a diagram showing the sensor output in this motor structure and the basic experiment results of coils 1 and 1 back electromotive force. Figure 5 is a block diagram showing the 1 drive method. , Figure 6 is a time chart for explaining tack signal formation, Figures 7 and 89
The figures are a cross-sectional view and a plan view showing a modified example of the stator yoke, FIG. 10 is a cross-sectional view of a rotating magnet and stator yoke showing another modified example, and FIG. 11.14 is a modified example of the rotating magnet. 12 and 13 are cross-sectional views showing still other modifications of the rotating magnet, and FIG. 15 shows a radius of the present invention. Disconnection of a shadow motor when applied to a directional gap type motor. Show a top view. 1.1', 1''...Magnetic field detection element, 26...Wiring board, 3...Stator yoke, 4...Rotor magnet, 9...Lower cylinder, 14, 14'...・Video head, 10...Stator coil, 18...Tack magnet, 40.40'...Concave part (spot facing part).Representative Patent Attorney: Michiaki Ko.Figure 1, Figure 2, Brother No. 30 (α) 4th Rowa (0-) 111 Ya Su□Z 5th ward 9th 6th gang 70th (0-) th gη (0-) 1st Bo Multicolor 11 Prisoner 73rd Force 74th Tomoe

Claims (1)

[Scope of Claims] A direct shaft connection of a DC brushless motor in which a rotor magnet is fixed to the upper cylinder rotating shaft, and a motor stator including at least a stator coil, a stator yoke, and a position detection sensor is fixed to the lower cylinder side. A cylinder motor for a VTR having a drive structure includes: a rotor magnet having a signal magnetic field generating section for detecting the rotational position of the video head fixed to the upper cylinder inside the center hole l or at its peripheral portion; and at least the rotor magnet. rotational position. A sensor for detecting the rotational position is placed in one of the small holes, notches, and five grooves provided in the plane thereof and at a position that is close to and facing the signal magnetic field generating part for detecting the rotational position during operation. Fixture with fixed yoke. A cylinder motor characterized by: