JPS6152631B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylinder motor for a video tape recorder.

1 to 4 show conventional examples of cylinder motors. This example is a configuration example of a cylinder motor that is directly connected to and drives a three-phase eight-pole flat brushless motor. Fig. 1 is a side sectional view thereof, Fig. 2 is a plan view of the stator, Fig. 3 is a plan view of the magnetic poles of the rotor magnet,
FIG. 4 is a drive circuit diagram. In this motor, a flat rotor magnet 1 having a magnetic pole surface divided into eight equal sectors and magnetized is fixed to a rotating shaft 18 via a rotor plate 6. A rotating upper cylinder 13 is fixed to the rotating shaft 18. Rotor magnet 1
A flat stator is fixed to the lower cylinder 12 at a position facing the magnetic poles of the stator.The stator has a flat stator coil 2 having a three-phase winding structure on a flat stator yoke 3. are fixed at predetermined positions on the outer peripheral edge of the stator coil 2 to detect the rotational position of the rotor magnet.
4" is fixed.

Furthermore, a wiring board 11 for mounting and wiring the magnetic field detection element and for wiring the stator coil 2 is provided at a position cut out in the side wall of the shield case 10. The magnetic field detection elements are provided at the same radial position at 30 degree intervals. Further, on the lower surface of the rotor plate 6, tack magnets 7, 7' with opposite polarities are fixed at positions corresponding to the video heads 14, 14', and the radius through which the magnetic poles of the tack magnets 7, 7' pass is fixed. At this position, a single magnetic field detection element 8 is separately provided and fixed to the shield case side via an arm 9. The video heads 14 and 14' are
They are fixed to the lower surface side of an upper cylinder 13 at intervals of 180 degrees, and the upper cylinder 13 is fixed to a rotating shaft 18 via a disk 15. Lower cylinder 12
Bearings are provided at the upper and lower ends of the central portion of the rotary shaft 18 to rotatably support the rotary shaft 18.

The magnetic pole position signals of the rotor magnet 1 detected by the magnetic field detection elements 4, 4', 4'' are amplified by the amplifier 60 and inputted to the energization signal forming circuit 65, and further this output pulse is inputted to the drive circuit 27. A current corresponding to the rotor magnet position is applied to the stator coil 2. This causes the rotor magnet 1 to rotate, and the upper cylinder 1 directly connected to it rotates.
3 and the tack magnets 7, 7' rotate. As the upper cylinder rotates, the video heads 14, 14' attached thereto alternately scan diagonally from the lower end of the video tape 20 toward the upper end, thereby recording or reproducing image signals. The tack magnets 7, 7' and the magnetic field detecting element 8 constitute a position detecting section for the video heads 14, 14', and at the same time as identifying the video head scanning the tape 20, the vertical synchronizing signal of the television signal is recorded at a predetermined position on the video tape. A signal (tack signal) is generated to control the rotational phase of the video heads 14, 14' so that the video heads 14, 14' are rotated. This signal is a pair of positive and negative pulses per cylinder rotation, and is sent to a phase comparison circuit 25 and compared with the phase of a reference signal 26. A phase error signal generated by the phase difference between the reference signal 26 and the rotational phase detection signal is input to the motor drive amplifier circuit 27, and the output to the motor is changed so that the phase error signal becomes zero. By matching the reference signal and the rotational phase signal in this way, stable image recording and reproduction becomes possible.

In the conventional cylinder motor configured in this manner, the element for detecting the rotational position of the rotor magnet and the element for detecting the rotational phase of the video head are provided separately, so that the number of wiring leads is large and the space occupied is large. Power consumption is high. It is difficult to sufficiently shield the magnetic field of the tack magnet. In particular, in small-sized, high-density mounting equipment, this negative effect is further exacerbated because the tack magnet and various heads and wiring are located in close proximity. Since the shield case side wall is cut out and the wiring board is provided here, the magnetic field of the rotor magnet easily leaks from this part, and cogging torque is likely to occur between the rotor magnet magnetic poles and the shield case cutout. . The cost is high. It has the following drawbacks.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a cylinder motor that is small, compact, low cost, has low magnetic noise, and has a structure suitable for mass production.

The cylinder motor of the present invention has the following features: (1) A minute magnet for signal generation (tack magnet) for detecting the rotational phase of the video head is fixed on the magnetic pole surface of the rotor magnet in the motor electromagnetic section, and a flat surface on the stator side is fixed opposite to this. One of the magnetic field detection elements for detecting the rotational position of the rotor magnet provided in the rotor magnet is also used for generating a rotational phase detection signal of the video head.

(2) The stator has a structure in which a small hole is provided at a predetermined position within the plane of the stator yoke and a magnetic field detection element is inserted into the hole. The aim is to improve efficiency, reduce magnetic leakage to the surroundings, and improve manufacturability.

Hereinafter, the present invention will be explained based on examples.

Fig. 5 is a longitudinal cross-sectional view showing one embodiment of the cylinder motor of the present invention, Fig. 6 is a plan view of a wiring board including a magnetic field detection element, Fig. 7 is a side view thereof, and Fig. 8 is a stator yoke. 9 is a plan view of the magnetic poles of the rotor magnet, and FIG. 10 is a plan view of the stator.

This embodiment is a cylinder motor having a structure in which a 3-phase 8-pole flat brushless motor is directly connected to the upper cylinder rotating shaft as in the conventional example, and the upper cylinder structure and lower cylinder structure are the same as in the conventional example. three magnetic field detection elements 4 for detecting the rotational position of the rotor magnet;
4' and 4'' are inserted into the small holes of the flat stator yoke 3, and a flexible board is used as the wiring board to eliminate the notch on the side surface of the shield case 10. As shown in Fig. 9, a tack magnet 55 of the same polarity is embedded at a predetermined radial position within the magnetic pole surface to create a locally strong magnetic field at this point.Also, the stator is fixed as shown in Fig. 10. Three small holes are provided in the plane of the child yoke 3 at 120 degree intervals at the same radial position as the tack magnet 55, and three magnetic field detection elements 4, 4', 4'' fixed to the wiring board are installed in these small holes. It has been inserted. As shown in FIGS. 6 and 7, the wiring board has a composite structure in which a flexible board 30 with a wiring conductor pattern is pasted onto a board 45 made of Bakelite or glass epoxy resin. Flexible board 30
As the upper conductor pattern, both a magnetic field detection element pattern and a coil terminal pattern 40 are provided. An insulating thin film is coated on the pattern surface. Rotor magnet 1 is tack magnet 5
5 is fixed to the rotating shaft 18 so that the position is at a predetermined angular position with respect to the video heads 14, 14'. In this example, one tack magnet is used, and when the rotor magnet 1 rotates, the magnetic field detection element 4
Since the magnetic field of the tack magnet 55 is applied once per rotation to elements 4' and 4'', superimposed on the magnetic field of the rotor magnet 1, the output voltage waveform of the elements 4, 4', and 4'' is based on the magnetic field of the rotor magnet 1. The voltage waveform generated by the tack magnet 55 is superimposed once per rotation on the voltage waveform generated by the tack magnet 55. Among these, the superimposed waveform as the output of one magnetic field detection element 4, 4', 4'' which takes the tack signal is separated and processed by an electronic circuit to generate a rotational phase signal of the video head.

FIG. 11 is a drive circuit diagram of the cylinder motor of FIG. 5. A voltage waveform corresponding to the magnetic field distribution in which the magnetic field of the rotor magnet 1 and the magnetic field of the tack magnet 55 are superimposed is generated in the magnetic field detecting elements 4, 4', 4''.The respective outputs are sent to amplifiers 60', 60'',
After being amplified in step 60, the signal is input to an energization signal forming circuit 65, where a pulse for operating the drive circuit 27 is generated. The drive circuit 27 supplies current to the stator coil 2 of the motor in accordance with the output pulse of the energization signal forming circuit 65, thereby providing rotational driving force to the rotor of the motor. In this example, the amplified signal of the magnetic field detecting element 4 is also input to the signal processing electronic circuit in order to separate the tack signal from the output of the magnetic field detecting element 4. The signal processing electronic circuit consists of a comparator 61, a phase adjustment circuit 62, a pulse forming circuit 63, and a phase comparison circuit 25, each of which separates, delays, and pulses the voltage signal generated by the magnetic field of the tack magnet, and performs phase comparison with a reference signal. and inputs the phase error signal to the motor drive circuit 27. The pulse forming circuit 63 uses a logic circuit to form pulse signals corresponding to the positions of the two video heads.

The drive circuit 27 operates to control the input to the motor coil 2 so as to make the phase error signal zero.

A back electromotive voltage induced in the stator coil 2 is used as a speed control signal for the motor. This method uses the stator coil as a frequency generator, and has a simple structure, low cost, and stable performance.

FIG. 12 is a sectional view showing another embodiment of the cylinder motor of the present invention, FIG. 13 is a plan view of the stator yoke to which a wiring board is attached, the surface facing the rotor magnet magnetic poles, and FIG. back view of yoke,
Fig. 15 is a plan view of the wiring board, Fig. 16 is a side view thereof, Fig. 17 is a plan view of the stator yoke, and Fig. 18 is a plan view of the wiring board.
This figure is a plan view of another stator yoke, and FIG. 19 is a diagram showing a method of fixing a wiring board and a magnetic field detection element to the stator yoke when the stator yoke of FIG. 18 is used. This embodiment is an example of a cylinder motor having a structure in which a 3-phase 8-pole flat brushless motor using three magnetic field detection elements is directly connected to the upper cylinder rotating shaft, similar to the embodiment shown in FIG. The structure of is the same as that of the embodiment shown in FIG. The stator of the motor includes three magnetic field detection elements 4, 4', and 4 for detecting the rotational position of the rotor magnet 1.
4'' is fixed at a predetermined position on a flexible thin plate-like substrate 30 or less (referred to as a flexible wiring board), and is inserted into a flat annular notch 51 provided at the inner peripheral edge of the flat annular stator yoke 3. The flexible wiring board 3 is fixed, and the stator coil 2 is further stacked and fixed at a predetermined angular position on top of the stator coil 2.
The magnetic field detection elements 4, 4', and 4'' arranged and fixed on the stator yoke have a height approximately equal to the notch depth of the notch 51 of the stator yoke.Flexible wiring board 30
has a conductor pattern for wiring on its surface, and is drawn out from the inner diameter of the stator yoke 3 through a notch at the innermost diameter of the shield case 10. As a result, the shield case 10 has no cutout on the side surface. It has a structure that allows As in the case shown in FIG. 9, the rotor magnet 1 has minute magnets (tack magnets) 55 of the same polarity embedded at predetermined radial positions within the inner surface of the magnetic poles so that a strong magnetic field distribution is locally generated at this point. It is set as. The mounting radius of the tack magnet 55 is the same as the mounting radius of the magnetic field detection elements 4, 4', 4''.
It is fixed to the rotating shaft 18 at a predetermined angular position with respect to the rotating shaft 14'. In this example, rotor magnet 1
The arrangement angle of the magnetic field detection elements 4, 4', and 4'' is selected to be 60 degrees in order to correspond to the 8-pole structure with a magnetic pole division angle of 45 degrees.The conductor patterns of the flexible wiring board are for the magnetic field detection elements and for the coil terminals. The coil terminal connection portion 35 of the flexible wiring board 30 is fixed to the back surface of the stator yoke 3, and the terminal connection of the stator coil 2 is performed here (14th pattern).
figure). The conductor pattern for the stator coil is made as wide as possible to ensure low resistance and avoid excessive current density. The stator yoke 3 has a structure in which only a flat annular notch 51 is provided on the inner peripheral edge as shown in FIG. 17, or a magnetic field detection element is further provided on the bottom of the notch 51 as shown in FIG. Three small holes 85 for precise positioning and fixing
In the case of a stator yoke having a structure with small holes, the magnetic field detection element is also provided with a piece of high magnetic permeability material 80 on the back surface of the flexible wiring board 30.
A structure with added is advantageous. By providing the notch 51 in the stator yoke 3, the wiring board can be placed directly under the rotor magnet magnetic pole surface without increasing the electromagnetic gap as described above, and the magnetic flux of the rotor magnet 1 can be directed toward the large radius part. Since the magnetic flux can be focused, the amount of magnetic flux linkage to the stator coil can be increased, and the position where the driving force is generated can be moved to a larger radius position, so the motor efficiency can be improved.Furthermore, since the magnetic field strength is weakened at the notch 51, the magnetic field detection element This has the advantage that the generated cogging torque and the torque ripple caused by the magnetic field of the tack magnet 55 can be reduced.

FIG. 20 is a top view of the motor section of the cylinder motor of this embodiment, and FIG. 21 is a perspective view of the shield case. This is a structure in which the flexible wiring board 30 is pulled out from a notch 75 provided in the inner diameter portion of the shield case 10. The shield case 10 has a simple shape, is easy to manufacture, and has a structure with high shielding effect.

This example is an example in which one tack magnet and three magnetic field detection elements are used at the same radius and the usable angular position in the case of an axial gap type flat three-phase brushless motor. When the detection elements are provided at different radial positions, when the number of magnetic field detection elements is other than three, when the number of motor phases is other than three, and when the motor structure is a radial gap type cylindrical structure. The basic configuration of the cylinder motor main body and drive system is the same as in this embodiment.

As the stator coil has a structure with a relatively large number of coil poles (the maximum value of the corresponding coil pole number is the same as the number of divided magnetic poles of the rotor magnet), the averaging effect on the generated torque improves, so the tack magnet magnetic field This is advantageous because it can alleviate the influence of torque ripple on torque ripple and improve the speed control signal level.

In addition, if the fixed position of the tuck magnet is selected on the rotor magnet magnetic pole surface where the tack magnet magnetic flux does not interlink with the stator coil as much as possible, or even if it does, the amount of interlinkage is extremely small, the tack magnet magnetic field distribution can be changed. Since the influence on motor torque can be reduced, motor torque ripple can be reduced. This position corresponds to the vicinity of the inner peripheral edge on the rotor magnet pole surface.

According to the present invention, the cylinder motor has the following features: (1) Since a minute magnet for a tack signal source (tack magnet) is provided in the magnetic field of the rotor magnet, magnetic noise due to the leakage magnetic field of the minute magnet is eliminated, and the DD structure is small and compact. Can be done.

(2) Since one of the magnetic field detection elements is also used to generate a rotational phase signal (tack signal) of the video head, there is no need to provide a separate sensor for tack.

(3) Since the stator coil and the wiring board with magnetic field detection element are each fixed on the stator yoke surface, it is easy to position the magnetic field detection element in relation to the stator coil, improving positioning accuracy and automating manufacturing. is easily possible.

(4) The stator yoke structure allows the magnetic flux effective for torque generation to be concentrated in a position with a relatively large radius, so the average drive radius can be increased and motor efficiency can be improved.

(5) Since the structure is such that the wiring board with the magnetic field detection element and the magnetic field detection element are installed at a small radius position, the amount of interlinkage of the magnetic flux of the magnetic field to the stator coil is small, and the reluctance torque caused by the magnetic field detection element is also small, so the torque ripple of the motor is reduced. can be made very small, resulting in effects such as a motor with low rotational unevenness.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional cylinder motor, Figure 2 is a sectional view of a conventional cylinder motor.
3 is a plan view of the magnet, FIG. 4 is a drive circuit diagram, FIG. 5 is a sectional view showing an embodiment of the cylinder motor of the present invention, and FIG. 6 is a diagram of the wiring board. 7 is a side view thereof, FIG. 8 is a plan view of the stator yoke, FIG. 9 is a plan view of the rotor magnet, and FIG. 10 is a plan view of the stator.
Fig. 1 is a drive circuit diagram, Fig. 12 is a sectional view showing another embodiment of the cylinder motor of the present invention, Fig. 13 is a plan view of the stator yoke, Fig. 14 is a back view thereof, and Fig. 15 is a circuit board. 16 is a plan view, and FIG. 16 is a side view.
17 and 18 are plan views of the stator yoke,
9 is a sectional view of a part of the stator yoke, FIG. 20 is a top view of a motor of another embodiment, and FIG. 21 is a perspective view of a shield case. 1: Rotor magnet, 3: Rotor yoke,
4, 4', 4'': magnetic field detection element, 7, 7', 55:
Tack magnet, 14, 14': video head, 30: flexible substrate.

Claims (1)

[Claims] 1. A rotating shaft rotatably supported by a lower cylinder, an upper cylinder fixed to the rotating shaft, and a disc-shaped rotating disc that is divided into multiple poles in the circumferential direction, magnetized, and fixed to the rotating shaft. a child magnet, a stator yoke facing the rotor magnet at a distance and fixed to the lower cylinder, and a stator coil facing the rotor magnet at a distance and attached to the stator yoke. , a cylinder motor having one or more magnetic field detection elements for detecting the position of the rotor magnet in order to switch the current supplied to the stator coil, and a tack magnet for indicating the rotational phase of the rotor magnet. The tack magnet having the same magnetic pole as the rotor magnet is arranged in the plane of at least one magnetic pole, so that the magnetic field of the magnetic pole becomes a strong magnetic field where the tack magnet is located, and the rotation on the stator yoke is One or more recesses are provided on the surface facing the child magnet, the magnetic field detection element is inserted into the recess so that its tip surface is substantially flush with the stator yoke, and at least one of the recesses A magnetic field detection element inserted into a recess provided at the same radial position superimposes a voltage due to the magnetic field of the rotor magnet and a voltage due to the magnetic field of the tack magnet. A cylinder motor that is characterized by being able to take out the cylinder.