JPH039019Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The present invention relates to a rotation detector, and is applied to a rotation detector that integrates a so-called PG (position (phase) pulse generator) and FG (frequency generator). be.

Background technology and its problems In a rotating system driven by a motor,
Some require both speed control and phase synchronization control. For example, the rotating head drum of a VTR
It is necessary to stabilize the rotation by speed control and to control the rotational phase by phase synchronization control so that the vertical synchronization signal of the video signal to be recorded is recorded on the side edge of the magnetic tape. For this purpose, a FG (frequency generator) and a PG (position pulse generator) are attached to the drive motor or rotating head drum, and the outputs of these actuate the speed servo device and phase servo device to perform speed control and phase control. It is being done.

1 and 2 show a conventional FG/PG integrated rotation detection device. FIG. 1 shows a detection conductor pattern on the fixed side, which is printed and wired on a printed circuit board. FIG. 2 shows the magnetization pattern of the ring-shaped magnet on the rotating side. Ring magnet 1
The end face of the magnet is subdivided and magnetized alternately at equal pitches along the direction of rotation. The conductor pattern on the fixed side has a large number of FG detection conductors 2 in the radial direction facing the end face of the magnet 1 with a micro gap in between, and these conductors 2 have the same pitch as the subdivided magnetization pattern of the magnet 1, Further, they are connected in series by outer and inner conductors 3 and 4 in the circumferential direction so as to form one continuous line.

As the magnet 1 rotates, the magnetic flux is cut by the FG detection conductor 2, and an electromotive force is generated in each conductor 2. The direction of the electromotive force is alternately reversed in the conductors corresponding to the N and S poles, but since the conductors 2 are connected so that each electromotive force is added, the electromotive force is derived from both ends of the connected conductors 2. The FG output signal shown in FIG. 3B is obtained from the terminals FG and C (common). The FG devices shown in FIGS. 1 and 2 are characterized in that by adding this electromotive force, unevenness in the magnetization pitch or the pitch of the conductor 2 is averaged out, and a very accurate FG output can be obtained.

PG detection conductor 5 in the radial direction as shown in Figure 1
is formed by further subdividing the FG detection conductor 2. In FIG. 1, conductors a to d constitute the PG detection conductor 5, and these are interposed at a pitch of 1/2 that of the FG detection conductor 2 and in phase with each other.
On the other hand, the rotating side magnet 1 is provided with a PG magnetized portion 6 on a part of its circumference, which is obtained by further dividing the FG magnetized pitch into 1/2. A PG detection signal shown in FIG. 3A is obtained from the terminals PG and C each time the PG magnetized portion 6 faces the PG detection conductor 5 once per rotation.

The PG magnetized portion 6 is located at 1/1 of the pitch of the FG detection conductor 2.
Since it has a magnetization pitch of 2, the FG detection conductor 2
The same polarity portions (N and N or S and S) of the PG magnetized portion 6 face two adjacent conductors spaced apart by one pitch, and the electromotive force of each conductor is canceled. Therefore, the PG magnetized portion 6 has no influence on the FG detection signal. Furthermore, the same polarity portions of the FG magnetized portions of two adjacent magnets face the PG detection conductor 5 (for example, the N pole and
The electromotive force is similarly canceled from the S pole for conductors c and d, and the FG magnetized portion has no effect on the PG detection signal.

However, depending on the requirements of the VTR servo circuit, it may be necessary to shift the phase of the PG detection signal shown in FIG. 3A by 1 to 2 degrees. in this case,
It is possible to phase shift on the circuit side, but the servo
Due to the configuration of the IC and servo circuit, the PG detection conductor 5
Shift 1 or 2 degrees with respect to FG detection conductor 2
A measure is taken to shift the phase of the PG detection signal.
However, with this configuration, the electromotive force canceling effect of the conductor is incomplete, and the influence of the PG magnetized portion 6 on the FG detection signal is reduced to 1 per rotation.
occurs twice. This effect mainly appears as AM modulation interference with the FG detection signal, and as a result, the FG
It becomes a frequency modulation component of the carrier frequency.

FIG. 4 is a waveform diagram when the degree of interference of the PG magnetized portion 6 with respect to the FG detection signal is observed by a wow/flat meter as the frequency fluctuation of the FG carrier, where A is the PG detection signal and B is the PG detection signal. When the conductor 5 is shifted by 2 degrees, C is the wow and flutter waveform when it is shifted by 1 degree, and D is the wow and flutter waveform when it is shifted by 0 degrees. When the phase is 0 degrees, in principle there is no mutual influence between FG and PG, and only a small frequency fluctuation due to the influence of core deviation between the magnet 1 and the detection conductor 2 is observed. For a one-degree deviation, frequency fluctuations due to interference in the PG magnetized portion 6 appear immediately after the PG detection signal. This effect is even greater for a 2 degree shift.

In speed servo circuits, as is well known, FG
Changes in the carrier frequency of the detection signal are detected and the acceleration and deceleration of the motor is controlled using error information relative to the reference. Therefore, when the disturbance component caused by the PG magnetized portion 6 as described above is added as a disturbance, the servo system is disturbed and rotational irregularity occurs once per rotation.
With VTRs, time axis fluctuations (jitter) occur in the playback signal.
This causes image cracking (a phenomenon in which the images do not match between the odd-numbered field screen and the even-numbered field screen).
Particularly in portable VTRs, the frequency band of the servo system is widened to improve response characteristics in consideration of rolling and vibration of the main body, so the speed servo is easily affected by the PG magnetized portion 6.

Purpose of the invention The present invention was devised in view of the above-mentioned problems.
The purpose is to reduce interference between magnetized parts and enable stable and accurate speed servoing.

Summary of the invention In the rotation detection device according to the invention, a subdivided magnetization array for speed detection is formed in the circumferential direction on one rotating side magnet 1 facing each other, and a corresponding pitch magnetization array is formed on the other stationary side printed wiring board. The speed detection conductor array 2 is formed in the circumferential direction and radially oriented, and
Conductor rows 5 for position detection are formed in a part of the circumferential direction at different positions in the radial direction and at different pitches, and a corresponding magnetized portion 6 for position detection is formed on the magnet 1. The present invention is characterized in that two signal lead-out conductors 7 and 8 are overlapped with each other with an insulating layer interposed therebetween in opposing regions of the position detecting series portion 6 and led out. With this configuration, mutual interference between the speed detection system and the position detection system can be reduced.

Example The present invention will be explained below based on examples.

FIG. 5 shows an improved conductor pattern for reducing mutual interference between FG and PG, in which the FG detection conductor 2 and the PG detection conductor 5 are separated from each other in the radial direction. The pitch of the conductors 2 and 5 is the same as in FIG. 1, and the phases are shifted by about 2 degrees from each other. As the rotating magnet 1, a ring-shaped magnet having a width that covers both the FG detection conductor 2 and the PG detection conductor 5 on the stationary side as shown in FIG. 6a is used. The magnetization pattern is similar to that in FIG.

In addition, as shown in Fig. 6b, only the PG magnetized part is extended in the centrifugal direction, or as shown in Fig. 6c,
It is also possible to use one in which the PG magnetized portion 6 is provided on the outside.

According to the configurations shown in FIGS. 5 and 6, mutual interference between the FG and PG is somewhat reduced, but interference with the FG detection signal by the PG magnetized portion 6 was still observed. This is connected to terminals FG and C (common).
The lead conductors 7 and 8 of the FG detection signal are the PG magnetized part 6
The inventors of the present invention believe that the cause is that the line segment r of these lead-out conductors 7 and 8 becomes part of the FG detection conductor and is influenced by the PG magnetized portion 6. This became clear.

Next, FIG. 7 is a conductor pattern diagram of an embodiment of the present invention that eliminates the above-mentioned drawbacks, in which the lead-out conductors 7 and 8 of the FG detection signal are arranged at the same angle in the passage area of the PG magnetized portion 6 of the magnet 1. It is separated into two layers, upper and lower. FIG. 8 shows the longitudinal direction (-
line), on the printed circuit board 9 there is a lead-out conductor 8 and other FG and PG detection conductors 2, 5.
is formed, and a lead-out conductor 7 is formed on top of the conductor 8 with an insulating layer 10 interposed therebetween.

According to this configuration, the PG magnetized portion 6 is always
Since magnetic fluxes of the same polarity act in the same way, the electromotive forces in the two line segments r seen from the terminals FG and C occur in mutually opposite directions (if one is +, the other is -),
These will be cancelled. Therefore, the interference of the PG magnetized portion 6 with respect to the FG detection signal is completely eliminated.
The speed servo system of the motor is no longer disturbed, and stable rotation at a constant speed can be obtained. Particularly in VTRs, uneven rotation of the rotating head drum is eliminated, and high-quality playback images without jitter can be obtained.

Effects of the invention As described above, in the present invention, the two signal lead-out conductors 7 and 8 of the speed detection conductor 2 are overlapped with each other via an insulating layer in the region where the magnetized portion 6 for position detection faces each other. , the magnetic fluxes of the same polarity of the magnetized part 6 for position detection simultaneously act on the lead-out conductors 7 and 8, and become electromotive forces in opposite directions when viewed from the output terminal, canceling each other out. There is no interference with the speed detection signal, allowing accurate rotational speed detection.

[Brief explanation of the drawing]

Figures 1 to 4 show a conventional FG/PG integrated rotation detector. Figure 1 is a schematic diagram of the detection conductor pattern on the fixed side, and Figure 2 is the magnetization pattern of the ring magnet on the rotating side. Figure 3 is a waveform diagram of the position detection signal (PG) and speed detection signal (FG), Figure 4 is the frequency of the speed detection carrier showing interference with the speed detection signal by the magnetized part of the position detection PG. FIG. 3 is a waveform diagram when modulation is observed with a wow/flat meter. 5 is a reference diagram showing an improved example of the conductor pattern of FIG. 1, and FIGS. 6 a to 6 c are diagrams of rotating side magnets used in combination with the conductor pattern of FIG. FIG. 7 is a schematic diagram showing a detection conductor pattern according to the present invention, and FIG. 8 is a partial sectional view taken along the line - in FIG. 7. In addition, in the symbols used in the drawings, 1...ring-shaped magnet, 2...FG detection conductor, 3, 4
...Conductor, 5...PG detection conductor, 6...PG magnetized portion, 7, 8... Leading conductor, 9... Printed circuit board, 10... Insulating layer.

Claims (1)

[Scope of utility model registration request] A rotation detecting device comprising a rotating side magnet and a stationary printed wiring board that face each other, the magnet having a subdivided magnetization array for speed detection in the circumferential direction, and the printed wiring board having a subdivided magnetization arrangement in the circumferential direction. It has speed detection conductor rows arranged at a predetermined pitch, and position detection conductor rows with different pitches are formed in a part of the circumferential direction at different positions in the radial direction. A magnetized portion for position detection corresponding to the conductor row for position detection is formed in a part of the magnet in the circumferential direction, and two signal lead-out conductors of the conductor row for speed detection are formed in the magnetized portion for position detection. 1. A rotation detection device characterized in that a region facing the rotation detection device is stacked vertically with an insulating layer interposed therebetween.